CN113445974B - Device and application as well as underground coal gasification pollution evaluation system and method - Google Patents

Abstract

The invention provides a device and application thereof, and a system and method for evaluating underground coal gasification pollution. The device comprises an experiment cabin, wherein the experiment cabin is provided with an experiment cavity; the experimental cavity comprises an experimental cavity end cover and an experimental cavity barrel body which are detachably connected, and the experimental cavity barrel body is composed of a double-layer barrel body comprising an inner barrel and an outer barrel and a barrel bottom; a cavity is formed between the inner wall of the outer cylinder and the outer wall of the inner cylinder, and a confining pressure applying part is arranged in the cavity and is connected with a confining pressure pipeline; the wall of the inner cylinder is provided with a hole pressure injection hole which is connected with a hole pressure pipeline; an experimental fluid injection channel and an experimental fluid output channel are arranged on the experimental cavity end cover and/or the barrel bottom of the experimental cavity barrel body; the experimental fluid injection channel and the experimental fluid output channel are communicated with the inside of the experimental cavity inner cylinder. The device can realize that the real occurrence condition of simulated coal can simulate the confining pressure and the pore pressure of the deep coal seam. The device is matched with other equipment to realize the underground coal gasification pollution evaluation considering the real occurrence condition of the coal bed.

Description

Device and application as well as underground coal gasification pollution evaluation system and method

Technical Field

The invention belongs to the technical field of underground coal gasification, and relates to a device and application, and an underground coal gasification pollution evaluation system and method.

Background

The underground coal gasification is a chemical coal mining technology which combines three processes of well construction, coal mining and gasification, and the underground coal seam is subjected to controlled thermal reaction and chemical reaction by a ground control means, so that synthesis gas containing combustible components such as hydrogen, methane and the like is produced. The technology can effectively utilize middle-deep (more than 800 m) coal seam resources which cannot be developed in mining engineering, can realize the effective development of thin coal seams, high sulfur content, high ash content, high inclination angles and 'three lower' coal seams, and can leave solid pollutants such as solid particles, residues, coal gangue and the like in the ground to reduce environmental pollution. Compared with ground coal gasification, the ground coal gasification has more advantages in economy, safety and resource utilization rate, and the later stage has potential to be transformed into an underground oil gas reservoir, and the ground coal gasification technology has huge development potential in the aspects of energy supply (hydrogen energy and natural gas) and peak regulation guarantee (underground reservoir), is an important technical approach for clean utilization of coal and energy conversion of China, and accords with the energy strategy of low carbon, green and sustainable development in China.

The risk of pollution in underground gasification of coal is an important reason limiting the development of this technology. Organic pollutants and inorganic pollutants can be generated in the coal gasification process, wherein the organic pollutants mainly comprise phenols, benzene, derivatives thereof and polycyclic aromatic hydrocarbons, the inorganic pollutants mainly comprise heavy metals (zinc, lead, cadmium and arsenic), ammine salts, sulfate and cyanide, and the pollutants exist in synthesis gas, residues and semicoke in a gaseous state and a solid state. Because the underground coal gasification operates in a high-temperature high-pressure underground closed environment, the synthesis gas transported through the stratum pores and cracks can pollute stratum water or surrounding stratum; after gasification, coal bed water enters the gasification cavity and then is soaked in solid residues and semicoke, so that pollutants enter stratum water, and the underground water layer is threatened greatly. Compared with ground coal gasification, the ground coal gasification has hysteresis in data transmission and operation actions, once the ground coal gasification causes environmental pollution, the ground coal gasification is difficult to effectively remedy, and even the project is shut down when the problem is serious. Therefore, the method has great significance for underground coal gasification construction and later environmental management by grasping the escape range of the synthesis gas and the leaching and migration rules of solid pollutants in the underground coal gasification process.

The underground coal gasification water pollution treatment and repair technology comprises a pumped ground treatment technology, a chemical oxidation technology, a biodegradation technology and the like, but the patent and research on a synthesis gas emission and underground water pollution evaluation test device are less. CN104297186a proposes a comprehensive experimental system for evaluating underground gasification pollution of coal and purifying and repairing underground pollution, but the experimental system cannot evaluate the dissipation condition of synthesis gas and simulate the occurrence state of a coal bed and confined water. At present, the following problems exist in the aspects of underground coal gasification synthesis gas dissipation and underground water pollution evaluation devices: 1. the occurrence state of the coal bed cannot be simulated, namely the vertical stress, the horizontal stress and the pore pressure of the coal bed cannot be simulated; 2. the underground coal gasification reaction under different gasifying agent types and technological parameters cannot be simulated; 3. the escape boundary of the synthesis gas cannot be detected and calibrated; 4. the test device can not realize the sewage detection and treatment function and can not provide support for optimizing the underground gasification sewage treatment scheme and the process parameter.

Disclosure of Invention

The invention aims to provide a physical model experimental device capable of simulating real occurrence conditions of coal, which can simulate confining pressure and pore pressure of a deep coal seam (for example, a coal seam below 1500 m). The object model experimental device is matched with other equipment to realize a coal underground gasification pollution evaluation test considering the real occurrence condition of a coal bed, and the experimental device can more scientifically and effectively guide the coal underground gasification environment evaluation and sewage treatment by simulating the more real coal underground gasification condition, so that the blank of the coal underground gasification pollution evaluation test technology is filled.

In order to achieve the above object, the present invention provides an apparatus comprising an experiment compartment provided with an experiment cavity;

the experimental cavity comprises an experimental cavity cover and an experimental cavity barrel body which are detachably connected, the experimental cavity barrel body is composed of a barrel bottom and a double-layer barrel body, and the double-layer barrel body comprises an inner barrel and an outer barrel; wherein the inner cylinder is used for loading a sample to be detected;

a cavity is formed between the inner wall of the outer cylinder and the outer wall of the inner cylinder, and a confining pressure applying part is arranged in the cavity and is connected with a confining pressure pipeline; the injection medium for applying confining pressure enters the confining pressure applying component through the confining pressure pipeline to realize that the confining pressure applying component applies confining pressure to the experimental cavity inner cylinder so as to realize that confining pressure is applied to a sample to be detected loaded in the experimental cavity inner cylinder;

a hole pressure injection hole is formed in the wall of the inner barrel, the hole pressure injection hole is connected with a hole pressure pipeline, and an injection medium for applying hole pressure enters the hole pressure injection hole through the hole pressure pipeline to apply hole pressure to a sample to be detected loaded in the inner barrel of the experimental cavity;

the experimental cavity cover and/or the barrel bottom of the experimental cavity barrel body are provided with experimental injection fluid channels and experimental production fluid channels; the experimental injection fluid channel and the experimental production fluid channel are communicated with the inside of the experimental cavity inner cylinder.

In the above device, the bottom of the experimental cavity barrel body and/or the experimental cavity end cover are provided with the experimental fluid injection channel and the experimental fluid output channel, specifically, the bottom of the experimental cavity barrel body can be provided with the experimental fluid injection channel and the experimental fluid output channel at the same time, and at this time, the experimental cavity end cover can be provided with or not provided with the experimental fluid injection channel and/or the experimental fluid output channel; the experimental fluid injection channel and the experimental fluid output channel can be arranged on the experimental cavity end cover at the same time, and the experimental fluid injection channel and/or the experimental fluid output channel can be or can not be arranged on the barrel bottom of the experimental cavity barrel body; an experimental fluid injection channel can be arranged on the end cover of the experimental cavity, and an experimental fluid output channel is arranged on the bottom of the experimental cavity barrel body; an experimental fluid output channel can be further arranged on the end cover of the experimental cavity, and an experimental fluid injection channel is arranged on the bottom of the experimental cavity barrel body.

In the above device, preferably, the confining pressure applying part includes a plurality of hydraulic rods, one ends of the hydraulic rods are fixed on the inner wall of the outer cylinder, and the other ends of the hydraulic rods act on the outer wall of the inner cylinder of the experiment cavity; more preferably, the hydraulic rod is provided with a hydraulic rod sliding head, the outer wall of the inner cylinder is provided with a hydraulic rod sliding rail, and the hydraulic rod is connected with the outer wall of the inner cylinder in a sliding connection mode by the hydraulic rod sliding head of the hydraulic rod and the hydraulic rod sliding rail of the outer cylinder; further preferably, the hydraulic rod is provided with a hydraulic rod fixing base, a hydraulic telescopic rod and a hydraulic rod sliding head which are sequentially connected, and the hydraulic rod is fixed on the inner wall of the outer cylinder through the hydraulic rod fixing base. In a preferred embodiment, the inner cylinder of the experiment cavity is a cuboid (comprising a cube) surrounded by 4 plates and provided with two open ends; for each plate, wherein only one end of the plate is abutted against the plate surface of the adjacent plate, and the plate surface of the plate is taken as the abutted plate surface of the adjacent plate; each plate can slide along the abutting plate surface; whereby the space formed by the plates can be reduced or enlarged in the horizontal and/or vertical direction. In the preferred scheme, the liquid pressing rod is fixed by the outer wall, and the inner wall is designed in a sliding way by the sliding rail, so that the problem that the inner wall plate can move on the plumb face when confining pressure is applied in a single direction is solved.

In the above device, preferably, the laboratory cavity is capable of withstanding a pressure of at least 1300 ℃ and at least 35MPa and achieving a seal; more preferably, the barrel bottom of the experimental cavity barrel body is made of temperature-resistant and pressure-resistant steel.

In the above apparatus, preferably, the pore pressure injection line is capable of withstanding a pressure of at least 35MPa, and the confining pressure injection line is capable of withstanding a pressure of at least 35 MPa.

In the above device, a check valve may be provided on the hole pressure injection line to prevent backflow of the hole pressure injection medium.

In the above device, preferably, the experiment cabin is further provided with a confining pressure data monitoring member, the confining pressure data monitoring member is used for collecting confining pressure data on the experiment cavity inner barrel, and the confining pressure data monitoring member preferably uses a stress sensor and the stress sensor is arranged on the barrel wall of the experiment cavity inner barrel.

In the above device, preferably, the experimental cabin is further provided with a hole pressure data monitoring member for collecting pressure data of the hole pressure injection hole, and the hole pressure data monitoring member preferably uses a pressure sensor and the pressure sensor is connected with the hole pressure injection hole.

In the above device, preferably, the experiment cabin is further provided with an experiment cabin shell, the experiment cabin shell is arranged outside the experiment cavity, the experiment cabin shell comprises a shell cover and a shell barrel body which are detachably connected, and the shell cover and the shell barrel body can be detachably connected together through at least two sealing bolts; more preferably, the experimental cabin is further provided with refractory bricks, and the refractory bricks are arranged in a cavity between the experimental cabin shell and the experimental cavity. Wherein, the experiment cabin shell can be made of high-pressure resistant steel plate materials. The experimental cavity shell barrel body can be integrally formed through a barrel wall and a barrel bottom to form the experimental cavity shell barrel body, and can also be detachably connected through the barrel wall and the barrel bottom to form the experimental cavity shell barrel body; preferably, the barrel wall and the barrel bottom are detachably connected together to form the experimental cavity shell barrel body.

In the above device, preferably, the experiment chamber is provided with a data acquisition assembly, the data acquisition assembly comprises a gas data acquisition member, and the gas data acquisition member is used for acquiring gas CO and CO in the inner barrel of the experiment chamber₂ 、CH₄ 、H₂ At least one of the escaping concentration and the escaping amount of (a); more preferably, the gas data acquisition member is further configured to acquire the oxygen concentration in the inner barrel of the experiment chamber, and to immediately alarm and stop the experiment once the oxygen concentration exceeds the explosion limit. In a specific embodiment, the gas data acquisition member comprises a gas detection sensor and a gas detection acquisition unit, wherein the gas detection sensor is arranged inside the experiment cabin, the gas detection acquisition unit is arranged outside the experiment cabin, and the gas detection sensor is connected with the gas detection acquisition unit. In a specific embodiment, according to the test requirement of the gas data, a plurality of gas detection sensors are arranged in the sample to be tested from top to bottom, from left to right and from front to back.

In the above device, preferably, the experimental cabin is provided with a data acquisition assembly, and the data acquisition assembly comprises at least one of a temperature data acquisition piece, a stress strain data acquisition piece and a pore pressure data acquisition piece; the temperature data acquisition part is used for acquiring temperature data of the sample to be detected loaded in the inner barrel of the experiment cavity, the stress strain data acquisition part is used for acquiring stress strain data of the sample to be detected loaded in the inner barrel of the experiment cavity, and the pore pressure data acquisition part is used for acquiring pore pressure of the sample to be detected loaded in the inner barrel of the experiment cavity. In a specific embodiment, the temperature data acquisition part comprises a thermocouple and a temperature acquisition device, wherein the thermocouple is arranged inside the experiment cabin, the temperature acquisition device is arranged outside the experiment cabin, and the thermocouple is connected with the temperature acquisition device. In a specific embodiment, the stress-strain data acquisition part comprises a stress-strain sensor and a stress-strain data acquisition device, wherein the stress-strain sensor is arranged in the experimental cabin, the stress-strain data acquisition device is arranged outside the experimental cabin, and the stress-strain sensor is connected with the stress-strain data acquisition device. In a specific embodiment, the pore pressure data acquisition part comprises a pressure sensor and a pressure acquisition device, wherein the pressure sensor is arranged inside the experimental cabin, the pressure acquisition device is arranged outside the experimental cabin, and the pressure sensor is connected with the pressure acquisition device. In one embodiment, several thermocouples are arranged in the sample to be tested from top to bottom, from left to right, and from front to back according to the temperature test requirements. In another embodiment, according to the stress-strain test requirement, a plurality of stress-strain sensors are arranged at the local part of the sample to be tested from top to bottom, from left to right and from front to back. In another embodiment, according to the test requirement of pore pressure, a plurality of pore pressure sensors are arranged at the local part of the sample to be tested from top to bottom, from left to right and from front to back.

In the above-described apparatus, preferably, the experimental cabin is provided with at least one data collection wiring channel for at least one of the temperature data collection wiring, the supply force strain data collection wiring, the pore pressure data collection wiring, and the gas data collection wiring. In a specific embodiment, the temperature data acquisition part comprises a thermocouple and a temperature acquisition device, wherein the thermocouple is arranged in the experimental cabin, the temperature acquisition device is arranged outside the experimental cabin, and the thermocouple and the temperature acquisition device are connected through a data wiring channel in a circuit manner. In a specific embodiment, the stress-strain data acquisition component preferably comprises a stress-strain sensor and a stress-strain data acquisition device, wherein the stress-strain sensor is arranged in the experimental cabin, the stress-strain data acquisition device is arranged outside the experimental cabin, and the stress-strain sensor and the stress-strain data acquisition device are in line connection through a data wiring channel. In a specific embodiment, the pore pressure data acquisition part comprises a pressure sensor and a pressure acquisition device, wherein the pressure sensor is arranged in the experimental cabin, the pressure change acquisition device is arranged outside the experimental cabin, and the pressure sensor and the pressure acquisition device are connected through a data wiring channel. In a specific embodiment, the gas data acquisition part comprises a gas detection sensor and a gas detection acquisition unit, wherein the gas detection sensor is arranged inside the experiment cabin, the gas detection acquisition unit is arranged outside the experiment cabin, and the gas detection sensor and the gas detection acquisition unit are connected through a data wiring channel.

In the above device, it is preferable that the confining pressure applying member can apply a vertical force and a horizontal force to the sample to be measured loaded in the inner cylinder of the experimental chamber. More preferably, the confining pressure applying part for applying the horizontal force and the confining pressure applying part for applying the vertical force are respectively connected with different confining pressure injection pipelines so as to realize the respective control of the horizontal force and the vertical force.

In a specific embodiment, the experimental cavity inner cylinder is a cylinder body with left and right openings, a cavity formed between the upper wall of the experimental cavity inner cylinder and the upper wall of the experimental cavity outer cylinder is provided with a confining pressure applying part, a cavity formed between the lower wall of the experimental cavity inner cylinder and the lower wall of the experimental cavity outer cylinder is provided with a confining pressure applying part, a cavity formed between the front wall of the experimental cavity inner cylinder and the front wall of the experimental cavity outer cylinder is provided with a confining pressure applying part, and a cavity formed between the rear wall of the experimental cavity inner cylinder and the rear wall of the experimental cavity outer cylinder is provided with a confining pressure applying part.

In the above device, preferably, the hole pressure injection hole is provided in the wall of the experimental cavity inner cylinder, and can realize that hole pressure is applied to the sample to be measured loaded in the experimental cavity inner cylinder in the horizontal direction. More preferably, different height hole pressure injection holes are connected with different hole pressure injection lines so as to realize different hole pressures applied to the different height hole pressure injection holes, thereby helping to simulate the change of the pore pressure with the depth. In a specific embodiment, the experimental cavity inner cylinder is a cylinder body with left and right ends open, and hole pressure injection holes are formed in the front wall and the rear wall of the experimental cavity inner cylinder.

In the above device, preferably, the experiment cavity cover and the experiment cavity barrel are detachably connected together by at least two sealing bolts.

In the above apparatus, preferably, the outer wall of the experimental cabin is rectangular parallelepiped in shape.

In the above device, the hole-pressing injection holes are preferably arranged equidistantly on the wall of the inner cylinder of the experimental chamber. In a specific embodiment, the shape of the inner barrel of the experiment cavity is cuboid with left and right ends open, and the front wall and the rear wall of the inner barrel of the experiment cavity are provided with hole pressing injection holes at equal intervals according to a longitudinal distance b with a transverse distance a.

In the above device, preferably, the experimental cabin is provided with a hole pressure relief hole.

In the device, the experimental cavity barrel body can be formed by integrally forming the outer barrel and the barrel bottom, and can also be detachably connected with the barrel bottom through the double-layer barrel body to form the experimental cavity barrel body.

The device can be used as a pollution evaluation device for the coal underground gasification pollution evaluation test, and when the device is used as the pollution evaluation device, the experimental cavity material selection meets the conventional requirements of the pollution evaluation device for the coal underground test, such as the high temperature resistance requirement, and the experimental cabin tightness meets the conventional requirements of the pollution evaluation device for the coal underground test.

The invention also provides application of the device in an underground coal gasification pollution evaluation test as a pollution evaluation device.

When the device is used as a pollution evaluation device, an experiment cavity for performing a sample to be tested can be referred to as a gasification cavity, a corresponding experiment cavity cover can be referred to as a gasification cavity cover, an experiment cavity barrel can be referred to as a gasification cavity barrel, an experiment cavity outer barrel can be referred to as a gasification cavity outer barrel, an experiment cavity inner barrel can be referred to as a gasification cavity inner barrel, an experiment cabin can be referred to as a pollution evaluation device body, an experiment cabin shell can be referred to as a pollution evaluation device shell, an experiment cabin shell cover can be referred to as a pollution evaluation device cover, an experiment cabin shell barrel can be referred to as a pollution evaluation device outer barrel, an experiment injection fluid channel can be referred to as a gasifying agent injection channel, and an experiment production fluid channel can be referred to as a synthesis gas production channel.

The invention also provides a coal underground gasification pollution evaluation system, which comprises a pollution evaluation device, a gasifying agent preparation unit, a confining pressure and pore pressure loading unit, a synthesis gas treatment unit, a sewage detection unit and an ignition unit;

the pollution evaluation device uses the device provided by the invention;

The gasifying agent preparation unit is connected with the experimental injection fluid channel of the pollution evaluation device and is used for injecting gasifying agent into the pollution evaluation device; the confining pressure loading unit and the pore pressure loading unit are respectively connected with a confining pressure injection pipeline and a pore pressure injection pipeline of the device and are used for applying confining pressure and pore pressure to the pollution evaluation device; the synthesis gas treatment unit is connected with the experimental produced fluid channel of the pollution evaluation device and is used for treating the synthesis gas produced by the device; the ignition unit is connected with the gasifying agent preparation unit and the device and is used for realizing the ignition operation of a sample to be detected loaded in an experimental cavity inner cylinder of the device; the sewage detection unit is connected with the pollution evaluation device and is used for detecting the water quality of sewage produced in the pollution evaluation device.

In the above-described underground coal gasification pollution evaluation system, preferably, the gasifying agent preparation unit is capable of realizing preparation of at least one of three gasifying agent types of air, oxygen-enriched air, a mixed gas of oxygen-enriched air and water vapor; more preferably, the gasifying agent preparation unit comprises an oxygen bottle, an oxygen flow control assembly, a nitrogen bottle, a nitrogen flow control assembly, a steam generator, a steam flow control assembly, an air compressor and an air flow control assembly, wherein the oxygen flow control assembly is connected with the oxygen bottle to control the supply flow of oxygen, the nitrogen flow control assembly is connected with the nitrogen bottle to control the supply flow of nitrogen, the steam flow control assembly is connected with the steam generator to control the supply flow of steam, and the air flow control assembly is connected with the air compressor to control the supply flow of air, and the oxygen flow control assembly, the nitrogen flow control assembly, the steam flow control assembly and the air flow control assembly can all comprise gas flow meters and valves with controllable opening degrees; further preferably, the gasifying agent preparation unit further comprises at least one of a pressure gauge for measuring the pressure of oxygen supplied by the oxygen cylinder and/or nitrogen supplied by the nitrogen cylinder and/or steam supplied by the steam generator and/or air supplied by the air compressor and/or supplied gasifying agent and a temperature gauge for measuring the temperature of oxygen supplied by the oxygen cylinder and/or nitrogen supplied by the nitrogen cylinder and/or steam supplied by the steam generator and/or air supplied by the air compressor and/or supplied gasifying agent, wherein the temperature gauge is preferably a thermocouple thermometer.

In the above-mentioned underground coal gasification pollution evaluation system, preferably, the sample to be detected loaded in the experimental chamber inner barrel of the pollution evaluation device includes a coal seam, and the coal seam is prefabricated with a well hole, and the well hole is respectively communicated with the experimental injection fluid channel and the experimental production fluid channel; more preferably, a combustible screen or casing is provided in the wellbore to support the wellbore. The sample to be tested preferably further comprises a top plate and a bottom plate, wherein the top plate is arranged above the coal bed, and the bottom plate is arranged below the coal bed. In one embodiment, the coal seam is comprised of cubic coal blocks arranged in sequence. In one embodiment, the top and bottom plates are arranged to meet a similarity criterion (typically the top and bottom plates are prepared to be consistent with the rock mechanics of the top and bottom plates of the actual formation). In one embodiment, the thickness of the top plate and the bottom plate are set to meet the similarity criterion, the thickness of the top plate in the test system is 1/5-1/40 of the thickness of the top plate of the real stratum, and the thickness of the bottom plate in the test system is 1/5-1/40 of the thickness of the bottom plate of the real stratum. Further preferably, when the experimental cabin is provided with a gas data acquisition part, the gas data acquisition part is used for acquiring gas data of the coal seam and the top plate in the experimental process, wherein the gas data comprise gas CO and CO₂ 、CH₄ 、H₂ 、O₂ At least one of the escaping concentration and the escaping amount (preferably further including the oxygen concentration); in a specific embodiment, a plurality of groups of gas detection sensors are arranged in a sample to be tested at equal intervals along the extending direction of the well bore, each group of gas detection sensors is arranged on a section perpendicular to the extending direction of the well bore on the sample to be tested, and each group of gas detection sensors comprises a plurality of gas detection sensors; wherein, on the setting cross section of every group gas detection sensor, set up a plurality of thermocouples along the longitudinal direction from roof to the well, set up a plurality of thermocouples along the horizontal direction. Further preferably, when the experimental cabin is provided with a temperature data acquisition part, the temperature data acquisition part is used for acquiring temperature data of the coal bed, the top plate and the bottom plate in the experimental process; in a specific embodiment, a plurality of groups of thermocouples are arranged in the sample to be tested at equal intervals along the extending direction of the well bore, each group of thermocouples is arranged on a section perpendicular to the extending direction of the well bore on the sample to be tested, and each group of thermocouples is provided with a plurality of thermocouples; wherein, on the arrangement section of each group of thermocouples, a plurality of rows of thermocouples are arranged in the longitudinal direction from the top plate to the bottom plate, and the row spacing between adjacent thermocouples closer to the borehole is smaller, and the spacing between adjacent thermocouples closer to the borehole is smaller in each thermocouple. Further preferably, when the experimental cabin is provided with a stress-strain data acquisition part, the experimental cabin is used for acquiring stress-strain data of the top plate; in a specific embodiment, the stress-strain sensors are disposed on the top of the coal seam and/or the top plate at equal intervals along the extending direction of the borehole, each set of stress-strain sensors is disposed on a section perpendicular to the extending direction of the borehole on the sample to be tested, and each set of stress-strain sensors is provided with a plurality of stress-strain sensors. Further preferably, when the experimental cabin is provided with a pore pressure data acquisition part, the pore pressure data acquisition part is used for acquiring pore pressure of the coal bed and/or the top plate; in a specific embodiment, the pore pressure sensors are arranged on the coal bed and/or the top plate at equal intervals along the extending direction of the well bore, each group of pore pressure sensors is arranged on a section perpendicular to the extending direction of the well bore on the sample to be tested, and each group of pore pressure sensors is provided with a plurality of pore pressure sensors.

In the above-mentioned underground coal gasification pollution evaluation system, preferably, the confining pressure and pore pressure loading unit includes a servo booster, a pressure controller, a confining pressure booster pump, a pore pressure booster pump, a confining pressure liquid source tank and a pore pressure liquid source tank, the confining pressure liquid source tank and the pore pressure liquid source tank respectively provide injection media for applying confining pressure and injection media for applying pore pressure, the confining pressure liquid source tank, the confining pressure booster pump and the servo booster are sequentially connected, the pore pressure liquid source tank and the pore pressure booster pump are sequentially connected, the servo booster is sequentially connected, a fluid outlet of the servo booster is respectively connected with a confining pressure injection pipeline and a pore pressure injection pipeline of the pollution evaluation device so as to realize that the confining pressure and pore pressure loading unit is respectively connected with the confining pressure injection pipeline and the pore pressure injection pipeline of the pollution evaluation device, and the pressure controller is connected with the servo booster so as to control the pressure application control of the servo booster. The method comprises the steps that an injection medium provided by a confining pressure liquid source tank is subjected to primary pressurization through a confining pressure booster pump, then subjected to secondary pressurization through a servo booster, and then flows into a confining pressure applying part of a pollution evaluating device through a confining pressure injection pipeline to provide pressure for the confining pressure applying part of the pollution evaluating device, wherein the servo booster carries out secondary pressurization on the injection medium according to a pressure value in a pressure controller and reaches a set value; and the injection medium provided by the pore pressure liquid source tank is subjected to primary pressurization through a pore pressure booster pump, then subjected to secondary pressurization through a servo booster, and then flows into a pore pressure injection hole of the pollution evaluation device through a pore pressure injection pipeline to provide pressure for the pore pressure injection hole of the pollution evaluation device, wherein the servo booster carries out secondary pressurization on the injection medium according to the pressure value in the pressure controller and reaches a set value. The servo booster is connected with the confining pressure pipeline and the pore pressure pipeline through high-pressure sealing pipelines. More preferably, the pollution evaluation device is provided with a confining pressure data monitoring piece and a hole pressure data monitoring piece, the confining pressure data monitoring piece is used for collecting confining pressure data on the inner barrel of the experimental cavity, the hole pressure data monitoring piece is used for collecting pressure data of the hole pressure injection hole, the confining pressure data monitoring piece and the hole pressure data monitoring piece are respectively connected with the pressure controller, and the data collected by the confining pressure data monitoring piece and the hole pressure data monitoring piece are transmitted to the pressure controller; the confining pressure data monitoring piece preferably uses a stress sensor which is arranged on the wall of the experimental cavity inner cylinder, and the hole pressure data monitoring piece preferably uses a pressure sensor which is connected with the hole pressure injection hole. The confining pressure and pore pressure loading unit preferably further comprises a computer, and the computer is connected with the pressure controller and used for monitoring, data acquisition and analysis of confining pressure and pore pressure loading and unloading processes in real time.

In the above-mentioned underground coal gasification pollution evaluation system, preferably, the ignition unit includes ignition controller and heating wire, ignition controller is as the ignition switch for initial ignition and continuous back ignition operation in the control test process, the heating wire sets up in the sample that awaits measuring that the experiment chamber loaded and is used for providing the required temperature of coal burning in the test process, cooperates the combustion improver to realize ignition operation. More preferably, one end of the heating wire is arranged in the sample to be tested loaded in the experiment cavity, and the other end of the heating wire is arranged outside the pollution evaluation device, so that the heating wire can be dragged in the sample to be tested loaded in the experiment cavity. The continuous backward process of the controlled injection point can be simulated by dragging the heating wire to simulate different ignition positions.

In the above-mentioned underground coal gasification pollution evaluation system, preferably, when the experimental cabin of the pollution evaluation device is provided with at least one of a gas data acquisition member, a temperature data acquisition member, a stress-strain data acquisition member and a pore pressure data acquisition member, the underground coal gasification pollution evaluation system further comprises a data acquisition unit including a computer connected with at least one of the gas data acquisition member, the temperature data acquisition member, the stress-strain data acquisition member and the pore pressure data acquisition member for storing and analyzing data acquired by the data acquisition member connected with the computer; the temperature data acquisition part is used for acquiring temperature data of the sample to be detected loaded in the inner barrel of the experiment cavity, the stress strain data acquisition part is used for acquiring stress strain data of the sample to be detected loaded in the inner barrel of the experiment cavity, and the pore pressure data acquisition part is used for acquiring pore pressure of the sample to be detected loaded in the inner barrel of the experiment cavity

In the above-mentioned underground coal gasification pollution evaluation system, preferably, the synthesis gas treatment unit includes a dust remover, a coke remover, a sulfur remover and a combustion chamber, wherein the dust remover, the coke remover and the sulfur remover are all arranged in front of the combustion chamber, i.e. the synthesis gas discharged from the experimental fluid output channel is treated by the dust remover, the coke remover and the sulfur remover and then enters the combustion chamber for treatment; the dust remover is used for removing solid dust in the synthesis gas discharged from the experimental fluid output channel, the decoking device is used for removing tar in the synthesis gas, the sulfur removing device is used for removing sulfur-containing toxic gas in the synthesis gas, and the combustion chamber is used for carrying out combustion treatment on the synthesis gas. More preferably, the synthesis gas processing unit further comprises a gas detection device, wherein the gas detection device is used for carrying out component analysis and metering on the synthesis gas processed by the dust remover, the coke remover and the sulfur remover; the gas detection device can be a gas chromatograph. The synthesis gas treatment unit preferably comprises a cooler, wherein the cooler is arranged in front of the dust remover, the coke remover and the sulfur remover and is used for cooling the synthesis gas exhausted from the experimental fluid output channel and avoiding the damage of high-temperature gas to a subsequent test device.

In the above-mentioned underground coal gasification pollution evaluation system, preferably, the sewage detection unit includes a water injection device connected to the experiment injection fluid passage of the pollution evaluation apparatus for injecting water into the pollution evaluation apparatus to displace the sewage in the experiment chamber inner cylinder, and a water quality detection device for detecting the water quality of the sewage discharged in the experiment chamber inner cylinder of the pollution evaluation apparatus. More preferably, the sewage detection unit further comprises a precipitation tank, the precipitation tank is connected with the experimental production fluid channel of the pollution evaluation device to precipitate particles such as solid residues and coal dust in sewage, and the water quality detection device is connected with the precipitation tank to detect the sewage after the precipitation tank precipitates so as to detect the water quality of the sewage discharged from the experimental cavity inner cylinder of the pollution evaluation device. Still preferably, the sewage detection unit includes a sewage purification device, the sewage purification device is connected with a water outlet of the precipitation tank for purifying sewage, the water quality detection device is further connected with the sewage purification device, and the water quality detection device is further used for detecting sewage quality of the sewage in the sewage purification process and after the sewage purification by the sewage purification device. Still preferably, the sewage purification device comprises a ground water primary purification device, a ground water secondary purification device and a ground water tertiary purification device, and the water quality detection device is respectively connected with the ground water primary purification device, the ground water secondary purification device and the ground water tertiary purification device and is used for detecting the sewage quality after the ground water primary purification device, the ground water secondary purification device and the ground water tertiary purification device carry out sewage purification; the sewage purification equipment carries out purification treatment on underground sewage according to the test requirement in a grading way, and the purified underground sewage is detected and evaluated by the water quality detection equipment. The water quality detection equipment preferably comprises an organic pollutant detection device and an inorganic pollutant detection device, wherein the organic pollutant detection device can be a gas chromatography-mass spectrometer (GC-MS), and the inorganic pollutant detection device can be a plasma emission-mass spectrometer (ICP-MS). The underground sewage can enter the sewage recovery tank for recovery after three-stage purification, and can also be recycled as injection water for displacement of sewage in the inner cylinder of the experiment cavity in subsequent experiments so as to simulate the process of pumping the underground water out of the ground. The sewage purifying equipment in the unit can also simulate sewage treatment technologies such as chemical oxidation technology, biodegradation technology and the like. In the above-mentioned underground coal gasification pollution evaluation system, it is preferable to use high-pressure-resistant pipelines capable of withstanding a pressure of at least 35MPa and achieving good sealing for all the pressure-bearing connecting pipelines.

The invention also provides a method for evaluating the underground coal gasification pollution, which is carried out by using the underground coal gasification pollution evaluation system, and comprises the following steps:

1) Preparing a top plate, a bottom plate and a coal bed for evaluating gasification pollution, setting heating wires in prefabricated wellholes in the coal bed according to well type prefabricated wellholes which are simulated as required and according to primary ignition positions, filling the bottom plate, the coal bed and the top plate into an experimental cavity inner barrel from bottom to top in the sequence of the bottom plate, the coal bed and the top plate, and connecting the underground gasification pollution evaluation system of coal;

2) Performing confining pressure and pore pressure application according to confining pressure and pore pressure values of the coal seam in the simulation area;

3) Performing coal seam simulated gasification: under the condition of injecting combustion improver into the coal bed, using an ignition unit to ignite the coal bed at an ignition position, and injecting gasifying agent into the coal bed to gasify the coal bed after the coal bed is in place, so as to complete the simulated gasification process of the coal bed; the synthesis gas generated in the coal seam simulated gasification process enters a synthesis gas unit for treatment and then is discharged;

4) Gasification cavity sewage detection: injecting water into the experiment cavity to displace the sewage in the gasification cavity, and detecting the water quality of the displaced sewage to realize water pollution evaluation;

Thus, the underground coal gasification pollution evaluation is completed.

In the above method for evaluating underground gasification pollution of coal, preferably, before preparing the top plate, the coal bed and the bottom plate for evaluating gasification pollution, rock mechanics test of simulating the real top plate and the bottom plate of the coal bed in the area is performed, and then the top plate and the bottom plate for gasification experiment are prepared according to the measured mechanics property and the material similarity principle;

in the above method for evaluating the underground gasification pollution of coal, it is preferable that a coal bed for gasification experiment is prepared from a coal block obtained from a coal bed in a simulation area. More preferably, coal dust and clay are used for smearing among coal blocks for preparing the coal bed for gasification experiments, so that the integrity of the coal bed is ensured. In one embodiment, coal pieces obtained from a simulated regional coal seam are cut into regular, cubic coal pieces, and the coal pieces are combined to form a coal seam for gasification experiments.

In the method for evaluating the underground coal gasification pollution, preferably, the joint of the coal bed, the top plate and the bottom plate is smeared with coal dust and clay, so that the tightness and the integrity of the coal bed, the top plate and the bottom plate are ensured.

In the above method for evaluating the underground gasification pollution of coal, sand is preferably filled between the coal bed and the inner wall of the inner cylinder of the experimental chamber. By utilizing good seepage and mechanical buffering characteristics of the fine sand layer, the fine sand buffering layer is filled between the simulated stratum material and the inner wall of the experimental cavity so as to reduce the damage of the pore pressure injection medium to the stratum material, reduce the injection difficulty of the pore pressure injection medium, shorten the pore pressure balance time of the top plate and the coal bed and improve the pore pressure balance efficiency.

In the above-described method for evaluating underground gasification pollution of coal, it is preferable that mounting holes for gas data collection material are formed in the top plate and/or bottom plate for evaluation of gasification pollution and/or the coal bed according to the need for evaluation of gasification pollution, and the gas data collection material is mounted in the top plate and/or bottom plate for evaluation of gasification pollution and/or the coal bed. More preferably, during step 3) simulated gasification of the coal seam, a gas data acquisition member is used for syngas emissions detection. The collected data may be stored and analyzed in a data collection unit (e.g., a computer). Further preferably, according to the detection result of the dissipation of the synthesis gas, a contour map of the volume and/or concentration of the dissipation gas is drawn, and the dissipation boundaries of different gases are calibrated; the type of the escaping gas comprises CO and CO₂ 、CH₄ And H₂ At least one of them.

In the above-described method for evaluating underground gasification pollution of coal, preferably, in step 3), during simulated gasification of the coal bed, the gas data acquisition member is used to monitor the oxygen concentration, and once the oxygen concentration exceeds the explosion limit, the test is immediately alerted and stopped.

In the above-described method for evaluating underground gasification pollution of coal, it is preferable that the mounting holes of the temperature data collection member, the stress-strain data collection member, and the pore pressure data collection member are prefabricated in the top plate and/or the bottom plate and/or the coal bed for evaluation of gasification pollution according to the gasification pollution evaluation requirement, and the temperature data collection member, the stress-strain data collection member, and the pore pressure data collection member are mounted in the top plate and/or the bottom plate and/or the coal bed for gasification experiment. More preferably, in the step 3) of the simulated gasification process of the coal seam, a temperature data acquisition part, a stress strain data acquisition part and a pore pressure data acquisition part are used for data acquisition. The collected data may be stored and analyzed in a data collection unit (e.g., a computer).

In the above method for evaluating the underground coal gasification pollution, it is preferable that a combustible screen and/or a casing is run into the prefabricated well bore of the coal bed to support the well bore.

In the underground coal gasification pollution evaluation method, when the U-shaped horizontal well gasification process is simulated, a single-hole well hole can be prefabricated in the coal bed. When the U-shaped horizontal well gasification process is simulated, the gasifying agent inlet and the synthesis gas outlet are respectively arranged at two opposite ends of the pollution evaluation device, namely the experimental injection fluid channel and the experimental production fluid channel are respectively arranged at two opposite ends of the experimental cavity inner barrel.

In the above method for evaluating the underground coal gasification pollution, preferably, after the underground coal gasification pollution evaluation system is connected in step 1), debugging is performed first, and the debugging is performed in step 2) without any problem.

In the above method for evaluating underground gasification pollution of coal, preferably, the values of the confining pressure and the pore pressure of the coal bed in the simulation area are obtained according to analysis of coal bed gas well data, coal bed drilling data, well testing data, array acoustic logging data and the like in the simulation area.

In the above method for evaluating the underground gasification pollution of coal, preferably, the confining pressure application includes applying a vertical force and a horizontal force. The vertical acting force and the horizontal acting force are used for simulating the overburden formation pressure and the horizontal principal stress.

In one embodiment, the confining pressure application process includes: the injection medium used for applying the confining pressure is subjected to primary pressurization through the confining pressure booster pump, the confining pressure value to be applied is input through the pressure controller, the pressure controller controls the servo booster to perform secondary pressurization on the injection medium used for applying the confining pressure after primary pressurization, and the confining pressure applying component in the experimental cavity applies the confining pressure to the inner cylinder of the experimental cavity under the action of the injection medium used for applying the confining pressure after secondary pressurization, so that the confining pressure is applied to the coal seam. More preferably, after the confining pressure data collected by the confining pressure data monitoring part reaches the confining pressure value set by the pressure controller, the confining pressure is maintained at the set value.

In the above-described method for evaluating underground coal gasification pollution, preferably, the pore pressure application includes applying pore pressures of different pressure values in the longitudinal direction to the coal bed so as to simulate the change in pore pressure with depth.

In one embodiment, the pore pressure application process includes: the injection medium used for applying the hole pressure carries out primary pressurization through the hole pressure booster pump, the hole pressure value to be applied is input through the pressure controller, the pressure controller controls the servo booster to carry out secondary pressurization on the injection medium used for applying the hole pressure after the primary pressurization, and the hole pressure injection hole in the experimental cavity applies the hole pressure under the action of the injection medium used for applying the hole pressure after the secondary pressurization. More preferably, after the pore pressure data collected by the pore pressure data monitoring part reaches the pore pressure value set by the pressure controller, the pore pressure is maintained at the set value.

In the above method for evaluating the underground coal gasification pollution, preferably, after the confining pressure and the pore pressure are applied, the pressure test is performed before the step 3), if the pressure test is qualified, the step 3) is performed, and if the pressure test is not qualified, the step 1) is performed again after the underground coal gasification pollution evaluation system is overhauled; the confining pressure and the pore pressure are applied for 36 hours, the confining pressure change range is within +/-5%, the pore pressure change range is within +/-5%, and the pressure test is qualified. The pressure test is qualified, and the coal underground gasification pollution evaluation system can be considered to have good tightness and the condition for carrying out subsequent operation.

In the above-described method for evaluating the pollution caused by underground coal gasification, it is preferable that at least one of the confining pressure data, the pore pressure data, the volume of the injection medium used during confining pressure application, the flow rate of the injection medium used during confining pressure application, the volume of the injection medium used during pore pressure application, and the flow rate of the injection medium used during pore pressure application is collected. In a specific embodiment, the confining pressure data monitoring part transmits the acquired confining pressure data to the pressure controller, the pore pressure data monitoring part transmits the acquired pore pressure data to the pressure controller, the servo pressurizer feeds back the confining pressure, the flow speed, the volume and other data of the injection medium used in the pore pressure applying process to the pressure controller, and the pressure controller transmits the confining pressure data, the pore pressure data, the liquid amount data, the flow speed data and the volume data to the computer for storage and/or display.

In the above method for evaluating underground coal gasification pollution, it is preferable that the gasifying agent injection pressure is smaller than the applied pore pressure. The real coal bed contains coal bed water, the domestic coal bed is generally in a state of underpressure, namely the pore pressure gradient of the coal bed is generally smaller than 1MPa/100m, and for safety and environmental protection, the injection pressure of the gasifying agent is smaller than the pore pressure of the coal bed in the underground coal gasification field test so as to reduce outward migration of synthetic gas in the gasification process, and the injection pressure of the gasifying agent is directly limited by the pore pressure of the coal bed. Therefore, in the underground coal gasification pollution evaluation method, the injection pressure of the gasifying agent is smaller than the applied pore pressure, so that the real site situation is better simulated.

In the above method for evaluating the pollution of underground coal gasification, preferably, the performing the simulated gasification of the coal seam includes: igniting the coal bed at a first ignition position by using an ignition unit under the condition of injecting a combustion improver into the coal bed, injecting a gasifying agent into the coal bed for coal bed gasification after the coal bed is ignited, repeating the processes of igniting the coal bed at the next ignition position and injecting the gasifying agent into the coal bed for coal bed gasification after the coal bed is ignited and ignited when the heat value of the synthetic gas generated by the coal bed gasification is reduced to 65-75% of the initial heat value until the final ignition position is completed and the operation of injecting the gasifying agent into the coal bed for coal bed gasification after the coal bed is ignited is completed, and completing the whole coal bed simulated gasification process; the synthesis gas generated in the coal seam simulated gasification process enters a synthesis gas unit for treatment and then is discharged; and (3) the synthesis gas generated in the coal seam simulated gasification process enters a synthesis gas unit for treatment and then is discharged. More preferably, the ignition positions are set in order from a position distant from the position where the gasifying agent is injected to a position close to the position where the gasifying agent is injected (the first ignition position is farthest from the position where the gasifying agent is injected than the other ignition positions, and the subsequent ignition positions are sequentially closer to the position where the gasifying agent is injected). In order to improve the coal gasification amount of a single gasification cavity, the amplitude reduction of the heat value of the synthetic gas in the ignition position changing process is controlled, the large fluctuation of the heat value of the synthetic gas is avoided, when the heat value of the synthetic gas is reduced to be within the range of 65% -75% of the initial heat value, the next ignition position repeatedly performs the processes of igniting the coal bed and injecting the gasifying agent into the coal bed to perform coal bed gasification after the coal bed is ignited, so that the gasification experiment at the new position is started. The ignition positions are sequentially arranged from the position far from the gasification agent injection position to the position close to the gasification agent injection position, so that the simulated controlled injection point continuous back process is realized.

In the above method for evaluating underground gasification pollution of coal, preferably, the pipeline is purged before the ignition of the coal bed in step 3); in a specific embodiment, the gasification agent preparation unit is controlled to provide nitrogen to carry out pipeline purging on the underground coal gasification pollution evaluation system before the coal bed is ignited, and the coal bed is started to be ignited after half an hour of purging.

In the above method for evaluating the underground gasification pollution of coal, preferably, the combustion improver is oxygen.

In the above-described underground gasification test method, the injection rates of the combustion improver and the gasifying agent may be determined in a conventional manner, for example, based on the gasifying agent pressure, the coal quality of the coal rock, the type of the flame retardant, and the simulation of the wellbore diameter.

In one embodiment, the step 3) of igniting the coal seam and injecting the gasifying agent into the impinged coal seam comprises the following steps: heating the electric heating wire in the well bore by the ignition controller, continuously injecting oxygen with small discharge capacity as combustion improver, injecting gasifying agent after confirming that the coal bed is in place, and controlling the injection flow and mode of the gasifying agent to gasify the coal bed.

In the above method for evaluating underground coal gasification pollution, preferably, the gasifying agent comprises: at least one of an air gasifying agent, an oxygen-enriched air gasifying agent and an oxygen-enriched air+water vapor gasifying agent. More preferably, when the gasifying agent is oxygen-enriched air+steam gasifying agent, the gasifying agent is injected in two stages or in one stage; wherein the two-stage injection comprises: the first stage is filled with oxygen-enriched air, the volume concentration of oxygen in the oxygen-enriched air is 21% -50%, and the flow rate of the oxygen-enriched air is preferably 0-30m³ /h; the stage is mainly coal oxidation combustion exothermic reaction; the second stage is injected with water vapor, preferably at a flow rate of 0-30m³ And/h, the stage mainly comprises water gas reaction and methanation reaction; the two stages are repeated in turn; the one-stage injection is to inject oxygen-enriched air and water vapor into the coal bed simultaneously, wherein oxygen in the oxygen-enriched airThe volume concentration is 21-50%, the mass ratio of water vapor to oxygen in the gasifying agent is 2:1-4:1, and the flow rate of the gasifying agent is preferably 0-30m³ /h。

In the above method for evaluating the underground gasification pollution of coal, it is preferable that the flow rate of the gasifying agent is preferably 0 to 30m³ /h。

In one embodiment, air is used as the gasifying agent, and the flow rate of the gasifying agent is controlled to be 0-30m³ And/h, when the calorific value of the synthesis gas generated by coal bed gasification is reduced to 65% -75% of the initial calorific value, dragging the heating wire to the next ignition position, and repeating the processes of igniting the coal bed and injecting the gasifying agent into the ignited coal bed.

In a specific embodiment, oxygen-enriched air is used as the gasifying agent, the volume concentration of oxygen in the oxygen-enriched air is 21-90%, and the flow rate of the gasifying agent is 0-30m³ And/h, when the calorific value of the synthesis gas generated by coal bed gasification is reduced to 65% -75% of the initial calorific value, dragging the heating wire to the next ignition position, and repeating the coal bed ignition and the coal bed ignition process, and injecting a gasifying agent into the coal bed for coal bed gasification.

In a specific embodiment, oxygen-enriched air and water vapor are used as gasifying agents, and two-stage injection is adopted for injecting the gasifying agents; the first section is filled with oxygen-enriched air, the volume concentration of oxygen in the oxygen-enriched air is 21% -50%, and the flow velocity of the oxygen-enriched air is 0-30m³ And/h, the stage is mainly coal oxidation combustion exothermic reaction; the second stage is injected with water vapor with the flow rate of 0-30m³ And/h, the stage mainly comprises water gas reaction and methanation reaction; the two stages are repeated in turn; when the calorific value of the synthesis gas generated by coal bed gasification is reduced to 65% -75% of the initial calorific value, the heating wire is dragged to the next ignition position, and the coal bed ignition and the process of injecting the gasifying agent into the coal bed for coal bed gasification after the coal bed is ignited and landed are repeated.

In a specific embodiment, oxygen-enriched air and water vapor are used as gasifying agents, and one-stage injection is adopted for injecting the gasifying agents; oxygen-enriched air and water vapor are injected into the coal seam at the same time, wherein the volume concentration of oxygen in the oxygen-enriched air is 21% -50%, the mass ratio of the water vapor to the oxygen in the gasifying agent is 2:1-4:1, and the oxygen is gasifiedThe flow rate of the agent is preferably 0-30m³ And/h, when the calorific value of the synthesis gas generated by coal bed gasification is reduced to 65% -75% of the initial calorific value, dragging the heating wire to the next ignition position, and repeating the coal bed ignition and the coal bed ignition process, and injecting a gasifying agent into the coal bed for coal bed gasification.

In one embodiment, the synthesis gas is subjected to component analysis and metering using a gas detection device such as a gas chromatograph in a synthesis gas processing unit to determine the heating value of the synthesis gas.

In the above-described method for evaluating the underground coal gasification pollution, it is preferable that the injection flow rate, pressure, and temperature data of the gasifying agent are collected in step 3).

In one embodiment, the process of simulating gasification of a coal seam to produce synthesis gas that enters a synthesis gas unit for treatment includes: the generated synthesis gas is subjected to dust remover, decoking device and sulfur remover to remove solid dust, tar and sulfur-containing toxic gas in the synthesis gas respectively, and then enters a combustion chamber to carry out combustion treatment on the synthesis gas, and the gas after the combustion treatment is discharged; wherein, the synthesis gas treated by the dust remover, the coke remover and the sulfur remover is subjected to component analysis and metering by using a gas chromatograph at intervals of 1-5 minutes.

In the above method for evaluating underground gasification pollution of coal, preferably, before the gasification cavity sewage is detected, the gasification cavity is purged with gas; on the one hand, the residual synthetic gas in the gasification cavity inner cylinder of the pollution evaluation device is discharged, and on the other hand, the temperature of the pollution evaluation device is cooled.

In the above method for evaluating underground gasification pollution of coal, preferably, in the process of detecting sewage in the gasification chamber, the water injected into the experiment chamber is coal bed water.

In the above method for evaluating underground gasification pollution of coal, preferably, in the process of detecting sewage in the gasification cavity, water is injected into the experiment cavity to displace the sewage in the gasification cavity, and then water quality detection is performed on the displaced sewage after solid large-particle sedimentation treatment is performed on the sewage.

In the above method for evaluating underground gasification pollution of coal, it is preferable that the gasification chamber sewage detection further includes purifying the displaced sewage and detecting the quality of the sewage during and after the purifying.

In a specific embodiment, injecting coal seam water into a well hole of a gasification cavity through a high-pressure water pump to replace sewage in the gasification cavity, wherein the pumping pressure is smaller than the pore pressure of the coal seam, the sewage is firstly subjected to sedimentation of large-size solid residues and coal dust through a sedimentation tank, and water quality analysis is carried out on the sewage of the sedimentation tank by water quality detection equipment to master the types and the contents of organic and inorganic pollutants; the sewage flowing through the settling tank sequentially enters a three-stage underground water purification device, the purification device carries out purification treatment on the sewage in a grading manner, the treated sewage is detected by water quality detection equipment, and all detection data are recorded in the water quality detection equipment. There are two treatment methods for the purified sewage, one is to open a sewage recovery tank for centralized treatment; the high-pressure water pump pumps the sewage into the gasification well hole again to simulate the ground pumping treatment process, and the sewage treatment process such as chemical oxidation technology, biological degradation technology and the like can be simulated in the process.

In the above method for evaluating underground gasification pollution of coal, it is preferable that after the gasification chamber sewage detection is completed, the confining pressure and the pore pressure are unloaded. Specifically: closing the confining pressure booster pump and the pore pressure booster pump, resetting the confining pressure and the pore pressure to zero through a pressure controller, slowly reducing the pumping pressure of a confining pressure pressurizing component (such as a hydraulic rod) in the experimental cavity, and slowly releasing acting force until the confining pressure value acquired by the confining pressure data monitoring piece is zero, so that the confining pressure is completely unloaded; opening a pore pressure relief hole on the experimental cabin until the pore pressure value acquired by the pore pressure acquisition piece is zero, so as to show that the pore pressure is completely unloaded; and after the confining pressure and the pore pressure are unloaded and cooled for 12 hours, carrying out the cross-sectional decomposition on the pollution evaluation device.

The real coal bed contains coal bed water, the domestic coal bed is in a state of underpressure, namely the pore pressure of the coal bed is generally smaller than 1MPa/100m, the injection pressure of the gasifying agent is smaller than the pore pressure of the coal bed in the underground coal gasification field test for safety and environmental protection, so that the outward migration of synthesis gas in the gasification process is reduced, the injection pressure of the gasifying agent in the underground coal gasification process is directly limited by the pore pressure of the coal bed, the gasification pressure of the shallow coal bed at 1500m is necessarily smaller than 15MPa, and in order to more scientifically guide the underground coal gasification pollution evaluation, the gasification simulation experiment needs to be carried out under the real pore pressure.

Compared with the prior art, the invention has the advantages that:

(1) The device provided by the invention can simulate the real occurrence condition of coal, can simulate the confining pressure and pore pressure of a deep coal seam (for example, a coal seam below 1500 m), solves the problems of confining pressure and pore pressure loading of the coal seam, and fills the blank of the test technology. In a preferred embodiment, simulating different coal seam formations and gasification wells (e.g., U-shaped horizontal wells, double horizontal wells) can also be implemented.

(2) The coal underground gasification pollution evaluation system formed by matching the device with other equipment can realize coal underground gasification pollution evaluation considering the real occurrence condition of a coal bed, and the device can more scientifically and effectively guide coal underground gasification environment evaluation and sewage treatment by simulating the more real coal underground gasification condition, so that the blank of the coal underground gasification pollution evaluation technology is filled.

(3) The coal underground gasification pollution evaluation method formed by the device and other equipment can simulate the real occurrence state of the coal bed, and can realize the leaching migration rule exploration (in a preferred scheme, the detection rule exploration of the escape of the synthesis gas can also be realized) of the solid pollutants under different gasification types and technological parameters under the real occurrence condition of the coal bed; the engineering practice can be guided more scientifically.

Drawings

Fig. 1 is a front view of the pollution evaluation device provided in example 1.

Fig. 2 is a left side view of the pollution evaluation device provided in example 1.

Fig. 3 is a plan view of the pollution evaluation device provided in example 1.

Fig. 4 is a schematic view of the experimental cavity inner wall (side) hole-pressing injection hole of the pollution evaluation device provided in example 1.

Fig. 5 is a partial enlarged view of the hole-pressing injection hole provided in example 1.

Fig. 6 is a partial enlarged view of the hydraulic lever provided in example 1.

FIG. 7 is an enlarged view of the gasification chamber inner barrel provided in example 1.

Fig. 8 is a longitudinal sectional view of the upper wall of the inner cylinder provided in example 1.

Fig. 9 is a horizontal sectional view of the upper wall of the inner cylinder provided in example 1.

Fig. 10 is a schematic diagram showing the arrangement of thermocouples of the pollution evaluation device provided in example 2.

Fig. 11 is a schematic diagram showing the arrangement of the pressure-pressure change sensor of the pollution evaluation device provided inembodiment 2.

Fig. 12 is a schematic diagram showing the arrangement of pore pressure sensors of the pollution evaluation device provided in example 2.

Fig. 13 is a schematic diagram showing the arrangement of a gas detection sensor of the pollution evaluation device provided inembodiment 2.

Fig. 14 is a schematic diagram of the underground coal gasification pollution evaluation system provided in example 2.

Fig. 15 is a flowchart of a method for evaluating the underground coal gasification pollution provided in example 3.

The main reference numerals:

1 oxygen cylinder, 2 nitrogen cylinder, 3 steam generator, 4 air compressor, 5 flow pressure meter, 6 thermocouple thermometer, 7 gasifying agent pipeline valve, 8 gasifying agent pipeline valve, 9 ignition controller, 10 gasifying agent injection channel, 11 pollution evaluation device left end cover sealing bolt, 12 pollution evaluation device outer barrel, 13 refractory brick, 14 gasifying cavity outer barrel, 15 hydraulic rod, 16 gasifying cavity inner barrel, 17 reserved detection pipe column, 18 temperature collector, 19 stress strain data collector, 20 pore pressure collector, 21 gas detection collector, 22 computer, 23 pollution evaluation device right end cover sealing bolt, 24 confining pressure, pore pressure wiring channel, 25 synthetic gas output channel, 26 roof, 27 coal seam, 28 well bore, 29 bottom plate, 30 gasifying cavity, 31 pollution evaluation device left end cover, 32 gasifying cavity left end cover sealing bolt, 33 gasifying cavity left end cover, 34 pore pressure relief pore, 35 pollution evaluation device right end cap, 36 pore pressure liquid source tank, 37 confining pressure liquid source tank, 38 confining pressure booster pump, 39 pore pressure booster pump, 40 pressure control valve, 41 servo booster, 42 pressure controller, 43 computer, 44 purifying pipeline control valve, 45 cooler, 46 dust remover, 47 decoking device, 48 sulfur remover, 49 gas detection device, 50 combustion chamber, 51 sewage detection unit control valve, 52 settling tank, 53 primary groundwater purification device, 54 secondary groundwater purification device, 55 tertiary groundwater purification device, 56 water quality detection device, 57 sewage tank control valve, 58 sewage recovery tank, 59 high pressure water pump, 60 groundwater tank control valve, 61 groundwater tank, 62 high pressure water pump control valve, 63 pressure sensor, 64 pore pressure injection hole, 65 check valve, 66 thermocouple, 67 stress strain sensor, 68 pore pressure sensor, 69 gas detection sensor, 70 hydraulic rod slide rail, 71 Kong Yabu wire casing, 72 hydraulic rod unable adjustment base, 73 hydraulic telescopic link, 74 hydraulic rod sliding head.

Detailed Description

The technical solution of the present invention will be described in detail below for a clearer understanding of technical features, objects and advantageous effects of the present invention, but should not be construed as limiting the scope of the present invention.

Example 1

The embodiment provides a pollution evaluation device which can be suitable for the underground coal gasification pollution evaluation, the structure of the pollution evaluation device is as shown in figures 1-9, the pollution evaluation device specifically comprises a pollution evaluation device body (i.e. an experiment cabin),

the pollution evaluation device body is provided with a gasification cavity 30 (i.e. an experimental cavity), a pollution evaluation device shell (i.e. an experimental cabin shell) andrefractory bricks 13; the pollution evaluation device shell is arranged outside thegasification cavity 30, and therefractory bricks 13 are arranged in a cavity between the pollution evaluation device shell and thegasification cavity 30; wherein,,

the pollution evaluation device shell is prepared by using a high-pressure resistant steel plate with the thickness of 1cm and can bear the high pressure of 35MPa, and is in a cuboid shape, and the specific dimension, the height, the width and the length are respectively 2m multiplied by 4m; the pollution evaluation device shell comprises a pollution evaluation device left end cover 31 (namely a shell cover) and a pollution evaluation device outer barrel 12 (namely a shell barrel body) which are detachably connected, and the pollution evaluation device outer barrel 12 and the pollution evaluation device left end cover 31 are detachably connected together through 8 pollution evaluation device left end cover sealing bolts 11; the pollution evaluation device outer barrel 12 is formed by detachably connecting a barrel wall of the pollution evaluation device outer barrel and a right end cover 35 of the pollution evaluation device through 8 sealing bolts 23 of the right end cover of the pollution evaluation device; 4 reserved detection tubular columns 17 (namely data acquisition wiring channels) are respectively arranged on the upper wall, the front wall and the rear wall of the outer barrel 12 of the pollution evaluation device and are used as wiring channels of a confining pressure data monitoring piece, a pore pressure data monitoring piece, a temperature data acquisition piece, a stress strain data acquisition piece, a pore pressure data acquisition piece and a gas data acquisition piece in the gasification cavity 30; the right end cover 35 of the pollution evaluation device is provided with 2 reserved columns which are respectively used as a confining pressure, a hole pressure wiring channel 24 and a hole pressure relief hole 34;

The gasification cavity 30 is in a cuboid shape and comprises a gasification cavity left end cover 33 (i.e. an experiment cavity cover) and a gasification cavity barrel body (i.e. an experiment cavity barrel body) which are detachably connected, the gasification cavity barrel body and the gasification cavity left end cover 33 are detachably connected together through 8 gasification cavity left end cover sealing bolts 32, the gasification cavity barrel body is composed of a double-layer barrel body and a barrel bottom and comprises a gasification cavity outer barrel 14 (i.e. an experiment cavity outer barrel) and a gasification cavity inner barrel 16 (i.e. an experiment cavity inner barrel), and the gasification cavity outer barrel 14 and the barrel bottom are integrally formed; the gasification chamber inner cylinder 16 is formed by enclosing 4 flat plates with the size of 2.2mx1.5m, and the 4 flat plates enclose a cuboid or cube with two open ends, for each flat plate, only one end of the flat plate is abutted against the surface of one flat plate adjacent to the flat plate, the surface of the flat plate is taken as the abutted surface of the other flat plate adjacent to the flat plate, and each flat plate can slide along the abutted surface (as shown in fig. 7-9); whereby the space formed by the flat plate can be reduced or enlarged in the horizontal and vertical directions; the gasification chamber outer cylinder 14 is prepared from temperature and pressure resistant steel and can bear high pressure of 35MPa and high temperature of 1300 ℃; a cavity is formed between the inner wall of the gasification cavity outer cylinder 14 and the outer wall of the gasification cavity inner cylinder 16, a confining pressure applying component is arranged in the cavity, the confining pressure applying component is connected with confining pressure pipelines (the confining pressure pipelines comprise a first confining pressure pipeline, a second confining pressure pipeline and a third confining pressure pipeline), and the confining pressure applying component is a hydraulic rod 15; the hydraulic rod 15 is provided with a hydraulic rod fixing base 72, a hydraulic telescopic rod 73 and a hydraulic rod sliding head 74 which are sequentially connected, and the outer wall of the gasification cavity inner cylinder 14 is provided with a hydraulic rod sliding rail 70; the hydraulic rod fixing base 72 of the hydraulic rod 15 is fixed on the inner wall of the air outer cylinder 14, the hydraulic rod sliding head 74 at the other end of the hydraulic rod 15 is arranged in the hydraulic rod sliding rail 70 of the gasification cavity inner cylinder 16, and the hydraulic rod sliding head 74 can slide along the hydraulic rod sliding rail 70; the injection medium for applying confining pressure enters the hydraulic rod 15 through a confining pressure pipeline to realize that the hydraulic rod 15 applies confining pressure to the gasification cavity inner cylinder 16 so as to realize that the confining pressure is applied to the sample to be detected loaded in the gasification cavity inner cylinder 16; the space formed between the upper wall of the gasification chamber inner cylinder 16 and the upper wall of the gasification chamber outer cylinder 14 is provided with 7×11 (7 rows×11 columns) hydraulic rods 15 connected with the first confining pressure pipeline at equal intervals, the space formed between the lower wall of the gasification chamber inner cylinder 16 and the lower wall of the gasification chamber outer cylinder 14 is provided with 7×11 (7 rows×11 columns) hydraulic rods 15 connected with the second confining pressure pipeline at equal intervals, the space formed between the front wall of the gasification chamber inner cylinder 16 and the front wall of the gasification chamber outer cylinder 14 is provided with 6×11 (6 rows×11 columns) hydraulic rods 15 connected with the third confining pressure pipeline at equal intervals, and the space formed between the rear wall of the gasification chamber inner cylinder 16 and the rear wall of the gasification chamber outer cylinder 14 is provided with 6×11 (6 rows×11 columns) hydraulic rods 15 connected with the third confining pressure pipeline at equal intervals;

Kong Yabu wire slots 71 and Kong Yabu wire slots 71 are respectively arranged in the front wall and the rear wall of the gasification cavity inner cylinder 16, and hole pressure pipelines are laid in the wire slots 71; the front wall and the rear wall of the gasification chamber inner cylinder 16 are provided with hole pressure injection holes 64, the hole pressure injection holes 64 are connected with hole pressure pipelines (the hole pressure pipelines comprise a first hole pressure pipeline, a second hole pressure pipeline … … and a tenth hole pressure pipeline), a one-way valve 65 is arranged on the hole pressure pipelines (the one-way valve 65 is arranged for avoiding backflow of hole pressure injection media), and the injection media for applying hole pressure apply hole pressure to a sample to be detected loaded in the gasification chamber inner cylinder 16 through the hole pressure pipelines into the hole pressure injection holes 64; the hole pressure injection holes 64 are formed in the cylinder wall of the gasification cavity inner cylinder 16, 10×24 hole pressure injection holes 64 (10 rows×24 columns) are formed in the front wall of the gasification cavity inner cylinder 16 at equal intervals, 10×24 hole pressure injection holes 64 are formed in the rear wall of the gasification cavity inner cylinder 16 at equal intervals (10 rows×24 columns), the hole pressure injection holes 64 in the front wall and the rear wall of the gasification cavity inner cylinder 16 are sequentially formed by a first row of hole pressure injection holes 64, a second row of hole pressure injection holes 64 and a tenth row of hole pressure injection holes … … from top to bottom, the hole pressure injection holes 64 in the front wall and the rear wall of the gasification cavity inner cylinder 16 are sequentially connected with a first hole pressure pipeline to a tenth hole pressure pipeline in rows, specifically, the first row of hole pressure injection holes 64 are connected with the first hole pressure pipeline, the second row of hole pressure injection holes 64 are connected with the second hole pressure pipeline in … …, and the tenth hole pressure injection holes 64 are connected with the tenth hole pressure pipeline;

Thegasification chamber 30 is further provided with a confining pressure data monitoring piece and a pore pressure data monitoring piece, wherein the confining pressure data monitoring piece is used for collecting confining pressure data of the gasification chamberinner cylinder 16, a stress sensor is selected and arranged on the wall of the gasification chamberinner cylinder 16; the hole pressure data monitoring piece is used for collecting pressure data of the holepressure injection hole 64, apressure sensor 63 is selected, and thepressure sensor 63 is connected with the holepressure injection hole 64;

the gasification chamber 30 is further provided with a data acquisition assembly comprising a gas data acquisition member, a temperature data acquisition member, a stress strain data acquisition member and a pore pressure data acquisition member; wherein, the gas data acquisition member is used for acquiring the gases CO and CO in the gasification cavity inner cylinder 16₂ 、CH₄ 、H₂ The gas data acquisition piece comprises a gas detection sensor 69 and a gas detection acquisition device 21, wherein the gas detection sensor 69 is arranged inside the gasification cavity inner cylinder 16, the gas detection acquisition device 21 is arranged outside the pollution evaluation device body, and the gas detection sensor 69 and the gas detection acquisition device 21 are connected in a line through a reserved detection pipe column 17; the temperature data acquisition part is used for acquiring temperature data of a sample to be detected loaded in the gasification cavity inner cylinder 16, and comprises a thermocouple 66 and a temperature acquisition device 18, wherein the thermocouple 66 is arranged inside the gasification cavity inner cylinder 16, the temperature acquisition device 18 is arranged outside the pollution evaluation device body, and the thermocouple 66 and the temperature acquisition device 18 are connected through a reserved detection tubular column 17 in a line manner; the stress-strain data acquisition part is used for acquiring stress-strain data of a sample to be detected loaded in the gasification cavity inner cylinder 16, and comprises a stress-strain sensor 67 and a stress-strain data acquisition device 19, wherein the stress-strain sensor 67 is arranged inside the gasification cavity inner cylinder 16, and the stress-strain data acquisition device 19 is arranged inside the gasification cavity inner cylinder 16 The stress-strain sensor 67 and the stress-strain data collector 19 are connected in a line through the reserved detection pipe column 17, and the stress-strain sensor 67 and the stress-strain data collector 19 are connected in a line through the reserved detection pipe column 17; the pore pressure data acquisition part is used for acquiring pore pressure of a sample to be detected loaded in the gasification cavity inner cylinder 16, and comprises a pore pressure sensor 68 and a pore pressure acquisition device 20, wherein the pore pressure sensor 68 is arranged inside the gasification cavity inner cylinder 16, the pore pressure acquisition device 20 is arranged outside the pollution evaluation device body, and the pore pressure sensor 68 and the pore pressure acquisition device 20 are connected through a reserved detection pipe column 17 in a line manner;

the pollution evaluation device body is provided with a gasifying agent injection channel 10 (i.e. an experimental injection fluid channel) and a synthesis gas output channel 25 (i.e. an experimental output fluid channel); the experimental injection fluid channel and the experimental output fluid channel are communicated with the gasification cavityinner cylinder 16; the gasifyingagent injection channel 10 is arranged on theleft end cover 33 of the gasifying cavity and is communicated with the outside through theleft end cover 31 of the pollution evaluation device, and the synthesisgas output channel 25 is arranged on the barrel bottom of the barrel body of the gasifying cavity and is communicated with the outside through the barrel bottom of theouter barrel 12 of the pollution evaluation device (namely, theright end cover 35 of the pollution evaluation device);

Example 2

The embodiment provides a coal underground gasification pollution evaluation system which can be suitable for coal underground gasification pollution evaluation, and the coal underground gasification pollution evaluation system is shown in fig. 10-14, and specifically comprises a pollution evaluation device, a gasifying agent preparation unit, a confining pressure and pore pressure loading unit, a synthesis gas processing unit, a data acquisition unit, a sewage detection unit and an ignition unit, wherein the pollution evaluation device is provided in the embodiment 1; the gasifying agent preparation unit is connected with the gasifying agent injection channel 10 of the pollution evaluation device and is used for injecting gasifying agent into the pollution evaluation device; the confining pressure and pore pressure loading unit is connected with a confining pressure injection pipeline and a pore pressure injection pipeline of the pollution evaluation device through a confining pressure and pore pressure wiring channel 24 of the pollution evaluation device respectively and is used for applying confining pressure and pore pressure to the pollution evaluation device; the synthesis gas treatment unit is connected with the synthesis gas output channel 25 of the pollution evaluation device and is used for treating the synthesis gas output by the pollution evaluation device; the ignition unit is connected with the gasifying agent preparation unit and the pollution evaluation device and is used for realizing the ignition operation of the sample to be detected loaded in the gasification cavity inner cylinder 16 of the pollution evaluation device; the sewage detection unit is connected with the pollution evaluation device and is used for detecting the water quality of sewage produced in the pollution evaluation device; the data acquisition unit is connected with a data acquisition piece gas detection collector 21, a temperature collector 18, a stress strain data collector 19 and a pore pressure collector 20 in the pollution evaluation device, and stores the data of the volume and concentration of the escaping gas, the oxygen concentration, the temperature, the stress strain and the pore pressure in the test process in real time for subsequent analysis;

The gasifying agent preparation unit can be used for preparing three gasifying agent types, namely air, oxygen-enriched air and mixed gas of the oxygen-enriched air and water vapor; the gasifying agent preparation unit comprises an oxygen bottle 1, an oxygen flow control assembly, a nitrogen bottle 2, a nitrogen flow control assembly, a steam generator 3, a steam flow control assembly, an air compressor 4 and an air flow control assembly, wherein the oxygen flow control assembly, the nitrogen flow control assembly, the steam flow control assembly and the air flow control assembly all comprise a flow pressure gauge 5, a thermocouple thermometer 6 and a gasifying agent pipeline sub valve 7 which are connected in sequence, wherein the opening of the gasifying agent pipeline sub valve can be controlled; the oxygen bottle 1 is connected with the oxygen flow control component to form an oxygen supply branch, the nitrogen bottle 2 is connected with the nitrogen flow control component to form a nitrogen supply branch, the steam generator 3 is connected with the steam flow control component to form a steam supply branch, and the air compressor 4 is connected with the air flow control component to form an air supply branch; the oxygen supply branch, the nitrogen supply branch, the steam supply branch and the air supply branch are connected in parallel and then connected with a gasifying agent injection channel 10 of the pollution evaluation device, so that the gasifying agent preparation unit is connected with the gasifying agent injection channel 10 of the pollution evaluation device, and a gasifying agent pipeline master valve 8 is arranged on the connecting pipeline;

The sample to be detected loaded in the gasification cavity inner barrel 16 of the pollution evaluation device comprises a top plate 26, a coal seam 27 and a bottom plate 29, wherein the top plate 26 is arranged above the coal seam 27, the bottom plate 29 is arranged below the coal seam 27, a borehole 28 is prefabricated in the coal seam 27, and the borehole 28 is respectively communicated with the gasifying agent injection channel 10 and the synthesis gas output channel 25; a combustible screen or casing is disposed in wellbore 28 for supporting the wellbore; the thermocouples 66 in the pollution evaluation device are used for collecting temperature data of the coal seam 27, the top plate 26 and the bottom plate 29 in the experimental process, 4 groups of thermocouples 66 are arranged in the sample to be tested at equal intervals along the extending direction of the well bore 28, each group of thermocouples 66 is arranged on a section perpendicular to the extending direction of the well bore 28 on the sample to be tested, each group of thermocouples 66 is provided with 20 thermocouples 66 in 3 rows, the specific arrangement is as shown in fig. 10, 3 heat extraction thermocouples 66 are arranged on the arranged section of each group of thermocouples 66 along the longitudinal direction from the top plate 26 to the bottom plate 29, the row spacing between adjacent thermocouples 66 is smaller when the thermocouples 66 are closer to the well bore 28, and the spacing between adjacent thermocouples 66 is smaller when the thermocouples 66 are closer to the well bore 28 in each heat extraction thermocouple 66; the stress-strain sensors 67 are arranged on the top of the coal seam 27 and the top plate 26 for collecting stress-strain data of the top plate 26, 4 groups of stress-strain sensors 67 are arranged in the sample to be tested at equal intervals along the extending direction of the borehole 28, each group of stress-strain sensors 67 is arranged on a section perpendicular to the extending direction of the borehole 28 on the sample to be tested, each group of stress-strain sensors 67 is provided with 2 rows of 14 stress-strain sensors 67, and the specific arrangement is shown in fig. 11, and the closer the adjacent stress-strain sensors 68 are to the borehole 28 on the arranged section of each group of stress-strain sensors 67; the pore pressure sensors 68 are arranged on the coal seam 27 for collecting pore pressure of the coal seam 27, 4 groups of pore pressure sensors 68 are arranged at equal intervals along the extending direction of the well bore 28, each group of pore pressure sensors 68 is arranged on a section perpendicular to the extending direction of the well bore 28 on a sample to be tested, and each group of pore pressure sensors 68 is provided with 2 pore pressure sensors 68 on the front side and the rear side of the well bore 28, and the specific arrangement is shown in fig. 12; the gas detection sensors 69 are arranged on the coal seam 27 and the top plate 26 for collecting the volume and concentration of the escaping gas and the concentration of oxygen, 4 groups of gas detection sensors 69 are arranged at equal intervals along the extending direction of the borehole 28, each group of gas detection sensors 69 is arranged on a section perpendicular to the extending direction of the borehole 28 on a sample to be tested, 3 pore pressure sensors 68 are respectively arranged on the front side, the rear side and the upper part of the borehole 28 according to the distance from the borehole from the large part to the small part, one of the 3 pore pressure sensors 68 on the upper part of the borehole is positioned in the top plate 26, and the other two pore pressure sensors are positioned in the coal seam 27, as shown in fig. 13; the set cross section of each group of thermocouples 66 is the same as the set cross section of the group of stress strain sensors 67, the set cross section of each group of pore pressure sensors 68 and the set cross section of each group of gas detection sensors 69;

The data acquisition unit comprises a computer, and the computer is connected with a data acquisition parttemperature acquisition device 18, a stress straindata acquisition device 19, a gasdetection acquisition device 21 and a porepressure acquisition device 20 in the pollution evaluation device, and stores the data of the volume and concentration of the dissipated gas, the oxygen concentration, the temperature, the stress strain and the pore pressure in the test process in real time for subsequent analysis;

the confining pressure and pore pressure loading unit comprises a servo booster 41, a pressure controller 42, a confining pressure booster pump 38, a pore pressure booster pump 39, a confining pressure liquid source tank 37, a pore pressure liquid source tank 36 and a computer 43, wherein the confining pressure liquid source tank 37 and the pore pressure liquid source tank 36 respectively provide injection medium oil for applying confining pressure and injection medium water for applying pore pressure; the confining pressure liquid source tank 37 is connected with the confining pressure booster pump 38 to form a confining pressure primary booster branch, the hole pressure liquid source tank 36 is connected with the hole pressure booster pump 39 to form a hole pressure primary booster branch, the confining pressure primary booster branch is connected with the servo booster 41 in parallel with the hole pressure primary booster branch, and a pressure control valve 40 is arranged on a connecting pipe, a fluid outlet of the servo booster 41 is respectively connected with a confining pressure injection pipeline and a hole pressure injection pipeline of the pollution evaluation device through a confining pressure and hole pressure wiring channel 24 of the pollution evaluation device, so that confining pressure and hole pressure loading units are respectively connected with the confining pressure injection pipeline and the hole pressure injection pipeline of the pollution evaluation device through the confining pressure and hole pressure wiring channel 24 of the pollution evaluation device; the pressure controller 42 is connected with the servo booster 41 to control the pressure application control of the servo booster 41, and the confining pressure data monitoring piece and the pore pressure data monitoring piece of the pollution evaluation device are respectively connected with the pressure controller 42 and transmit the data acquired by the confining pressure data monitoring piece and the pore pressure data monitoring piece into the pressure controller 42; the computer 43 is connected with the pressure controller 42 and is used for monitoring, data acquisition and analysis of the confining pressure and pore pressure loading and unloading processes in real time; when confining pressure pressurization is carried out, the injection medium provided by the confining pressure liquid source tank 37 is subjected to primary pressurization through the confining pressure booster pump 38, then subjected to secondary pressurization through the servo booster 41, and then flows into the confining pressure applying part of the pollution evaluation device through the confining pressure injection pipeline to provide pressure for the confining pressure applying part of the pollution evaluation device, wherein the servo booster 41 carries out secondary pressurization on the injection medium according to the pressure value in the pressure controller 42 and reaches a set value; in the case of pore pressure pressurization, the injection medium supplied from the pore pressure liquid source tank 36 is subjected to primary pressurization by the pore pressure booster pump 39, then subjected to secondary pressurization by the servo booster 41, and then flows into the pore pressure injection hole of the pollution evaluation device through the pore pressure injection line to supply pressure to the pore pressure injection hole of the pollution evaluation device, wherein the servo booster 41 performs secondary pressurization on the injection medium according to the pressure value in the pressure controller and reaches a set value. The servo booster is connected with the confining pressure pipeline and the pore pressure pipeline through high-pressure sealing pipelines;

The ignition unit comprises an ignition controller 9 and an electric heating wire, wherein the ignition controller 9 is arranged on a pipeline connected with the gasification agent preparation unit and the pollution evaluation device, the ignition controller 9 is used as an ignition switch for controlling initial ignition and continuous backward ignition operation in the test process, the electric heating wire is arranged in awell hole 28 of a sample to be tested loaded by the pollution evaluation device (specifically, the electric heating wire is arranged through a gasificationagent injection channel 10, one end of the electric heating wire is arranged in thewell hole 28, and the other end of the electric heating wire is arranged outside the pollution evaluation device) for providing the temperature required by coal combustion in the test process and realizing ignition operation in cooperation with a combustion improver; the continuous backward process of the controlled injection point can be simulated by dragging the heating wire to simulate different ignition positions;

the synthesis gas treatment unit comprises a cooler 45, a dust remover 46, a coke remover 47, a sulfur remover 48 and a combustion chamber 50 which are sequentially connected, wherein a gas detection device 49 is arranged on a connecting pipeline of the sulfur remover 48 and the combustion chamber 50, the cooler 45 is connected with a synthesis gas output channel 25 of the pollution evaluation device so as to realize that the synthesis gas treatment unit is connected with the synthesis gas output channel 25 of the pollution evaluation device, and a purifying pipeline control valve 44 is arranged on the connecting pipeline; the cooler 45 is used for cooling the synthesis gas discharged from the synthesis gas output channel 25 of the pollution evaluation device, the dust remover 46 is used for removing solid dust in the synthesis gas discharged from the synthesis gas output channel 25 of the pollution evaluation device, the coke remover 47 is used for removing tar in the synthesis gas, the sulfur remover 48 is used for removing sulfur-containing toxic gas in the synthesis gas, the combustion chamber 50 is used for carrying out combustion treatment on the synthesis gas, and the gas detection equipment 49 is used for carrying out component analysis and metering on the synthesis gas processed by the dust remover 46, the coke remover 47 and the sulfur remover 48; wherein the gas detection device 49 is a gas chromatograph/mass spectrometer (GCMS);

The sewage detection unit comprises an underground water tank 61, a water injection device, a sewage purification device, a precipitation tank 52, a water quality detection device 56 and a sewage recovery tank 58; the water injection equipment is a high-pressure water pump 59, the underground water tank 61 is connected with a pump inlet of the high-pressure water pump 59, an underground water tank control valve 60 is arranged on a connecting pipeline, a pump outlet of the high-pressure water pump 59 is connected with the gasifying agent injection channel 10 of the pollution evaluation device, and a high-pressure water pump control valve 62 is arranged on the connecting pipeline; the sewage purification equipment comprises a primary underground water purification device 53, a secondary underground water purification device 54 and a tertiary underground water purification device 55, wherein the sedimentation tank 52, the primary underground water purification device 53, the secondary underground water purification device 54 and the tertiary underground water purification device 55 are sequentially connected, a water inlet of the sedimentation tank 52 is connected with the synthesis gas output channel 25 of the pollution evaluation device, a sewage detection unit control valve is arranged on a connecting pipeline, and the water quality detection equipment 56 is respectively connected with the sedimentation tank 52, the primary underground water purification device 53, the secondary underground water purification device 54 and the tertiary underground water purification device 55 and is used for detecting the sewage after sedimentation in the sedimentation tank 52, the sewage after purification in the primary underground water purification device 54, the sewage after purification in the secondary underground water purification device 55 and the sewage after purification in the tertiary underground water purification device 56; the water outlet of the underground water three-stage purification device 55 is respectively connected with the water inlet of the sewage recovery tank 58 and the pump inlet of the high-pressure water pump 59, and a sewage pipe control valve 57 is arranged on the connecting pipeline of the water outlet of the underground water three-stage purification device 55 and the sewage recovery tank 58; the water quality detection device 56 comprises an organic pollutant detection device and an inorganic pollutant detection device, wherein the organic pollutant detection device adopts a gas chromatography-mass spectrometer (GC-MS), and the inorganic pollutant detection device adopts a plasma emission-mass spectrometer (ICP-MS); in the underground coal gasification pollution evaluation system, all pressure-bearing connecting pipelines use high-pressure-resistant pipelines which can bear at least 35MPa pressure and realize good sealing, and valves on all pipelines can effectively control the communication of the pipelines and can be sealed well.

Example 3

The embodiment provides a method for evaluating underground coal gasification pollution, which uses the underground coal gasification pollution evaluation system provided in theembodiment 2 to perform a flow as shown in fig. 15, and comprises the following steps:

1)Top plate 26,bottom plate 29 andcoal seam 27 for gasification test were prepared: carrying out rock mechanical tests according to the core data of the top plate and the bottom plate of the coal bed in the area to be simulated, measuring the mechanical properties (elastic modulus, poisson ratio, tensile strength and compressive strength), and preparing thetop plate 26 and thebottom plate 29 for the gasification experiment by combining the material similarity principle; thecoal layer 27 for gasification experiment was prepared by cutting coal pieces obtained from a coal layer in a simulation area into regular cubic coal pieces of 0.4m×0.4m, with the thickness of thetop plate 26 being 0.25m, the length being 2.2m, the width being 1.5m, the thickness of thecoal layer 27 being 1m, the length being 2.2m, the width being 1.5m, and the thickness of thebottom plate 29 being 0.25m, the length being 2.2m, the width being 1.5 m;

prefabricating thewellbore 28 and providing heating wires in theprefabricated wellbore 28 according to the initial firing position: prefabricating awell hole 28 required by a simulated U-shaped horizontal well gasification process in acoal seam 27, in particular prefabricating a single-hole well hole 28 in thecoal seam 27, wherein the diameter of the manually prefabricated wellhole 28 is 10cm, putting a combustible sleeve into the well hole to support thewell hole 28, and setting the initial position of an electric heating wire at a position which is about 0.5m away from the barrel bottom of the gasification cavity barrel body, namely 0.5m away from the right end surface of the gasification cavityinner barrel 16 after the coal seam is filled into the gasification cavityinner barrel 16; the gasifyingagent injection channel 10 and the synthesisgas output channel 25 are respectively arranged at the left end and the right end of the pollution evaluation device body;

Top plate 26,bottom plate 29, andcoal seam 27 are pre-installed withgas detection sensor 69, thermocouple 66,stress strain sensor 67, and pore pressure sensor 68: prefabricating mounting holes of a gas data acquisition part, a temperature data acquisition part, a stress strain data acquisition part and a pore pressure data acquisition part in thetop plate 26, thebottom plate 29 and thecoal seam 27, and mounting agas detection sensor 69, a thermocouple 66, astress strain sensor 67 and apore pressure sensor 68 in thetop plate 26, thebottom plate 29 and thecoal seam 27; arrangement ofgas detection sensor 69, thermocouple 66, stress-strain sensor 67,pore pressure sensor 68 inroof 26,floor 29, andcoal seam 27 the arrangement ofgas detection sensor 69, thermocouple 66, stress-strain sensor 67,pore pressure sensor 68 in example 2 (see fig. 10-13);

top plate 26,bottom plate 29 andcoal seam 27 are filled: filling thebottom plate 29, thecoal seam 27 and thetop plate 26 into the gasification cavityinner barrel 16 in the order of thebottom plate 29, thecoal seam 27 and thetop plate 26 from bottom to top in the gasification cavityinner barrel 16; wherein, coal dust and clay are used for smearing among coal blocks of thecoal bed 27 for preparing gasification experiments, so as to ensure the integrity of the coal bed; the joints of thecoal seam 27, thetop plate 26 and thebottom plate 29 are smeared with coal dust and clay, so that the tightness and the integrity of the coal seam, the top plate and the bottom plate are ensured; sand is filled between thecoal seam 27 and the inner wall of the gasification chamberinner cylinder 16;

Then the pollution evaluation device is assembled, and the whole underground coal gasification pollution evaluation system is connected; debugging the connected underground coal gasification pollution evaluation system (determining that the circuit is connected correctly, each component is normal in function and good in switching performance), and performing the subsequent step 2) after debugging has no problem;

2) Performing confining pressure and pore pressure application according to confining pressure and pore pressure values of coal beds in the simulation areas:

the simulated coal seam depth in this embodiment is 1000m, the vertical stress on the coal seam is 25.4MPa, the maximum horizontal main stress is 18MPa, the minimum horizontal main stress is 16.7MPa, the well bore is set along the minimum horizontal main stress, and the pore pressure of the coal seam is 8.7MPa.

The hydraulic rod 15 connected to the first confining pressure line, the hydraulic rod 15 connected to the second confining pressure line, and the hydraulic rod 15 connected to the third confining pressure line are controlled to perform confining pressure application, specifically: the injection medium for applying confining pressure is subjected to primary pressurization through the confining pressure booster pump 38, the confining pressure value to be applied is input through the pressure controller 42 (wherein the vertical acting force is that the confining pressure value applied by the hydraulic rod 15 connected with the first confining pressure pipeline is 25.4MPa, the horizontal main stress is that the confining pressure value applied by the hydraulic rod 15 connected with the third confining pressure pipeline is 18 MPa), the pressure controller 42 controls the servo booster 41 to carry out secondary pressurization on the injection medium for applying confining pressure after primary pressurization, and the hydraulic rod 42 in the gasification cavity 30 slowly displaces under the action of the injection medium for applying confining pressure after secondary pressurization so as to apply the vertical acting force and the horizontal acting force on the gasification cavity inner cylinder 16 for simulating the coal seam overburden formation pressure and the maximum horizontal main stress; after the confining pressure data acquired by the confining pressure data monitoring part reach the confining pressure value set by the pressure controller 42, the confining pressure is maintained to be unchanged at the set value; hole pressure application is performed by controlling the hole pressure injection hole 64 connected to the first hole pressure line, the hole pressure injection hole 64 … … connected to the second hole pressure line, and the hole pressure injection hole 64 connected to the tenth hole pressure line, respectively, specifically: the injection medium for applying the hole pressure is subjected to the first stage pressurizing by the hole pressure booster pump 39, and the value of the confining pressure to be applied is inputted by the pressure controller 42 (wherein the value of the hole pressure applied by the hole pressure injection hole 64 connected to the first hole pressure line is 8.67MPa, the value of the hole pressure applied by the hole pressure injection hole 64 connected to the second hole pressure line is 8.68MPa, the value of the hole pressure applied by the hole pressure injection hole 64 connected to the third hole pressure line is 8.69MPa, the value of the hole pressure applied by the hole pressure injection hole 64 connected to the fourth hole pressure line is 8.69MPa, the value of the hole pressure applied by the hole pressure injection hole 64 connected to the fifth hole pressure line is 8.70MPa, the hole pressure value applied by the hole pressure injection hole 64 connected with the seventh hole pressure pipeline is 8.72MPa, the hole pressure value applied by the hole pressure injection hole 64 connected with the eighth hole pressure pipeline is 8.72MPa, the hole pressure value applied by the hole pressure injection hole 64 connected with the ninth hole pressure pipeline is 8.73MPa, the hole pressure value applied by the hole pressure injection hole 64 connected with the tenth hole pressure pipeline is 8.74 MPa), the pressure controller 42 controls the servo pressurizer 41 to perform secondary pressurization on the injection medium used for applying the hole pressure after primary pressurization, and the hole pressure injection hole 64 in the gasification cavity 30 applies the hole pressure to the coal seam 27 under the action of the injection medium used for applying the hole pressure after the secondary pressurization; when the pore pressure data acquired by the pore pressure data monitoring piece reach the pore pressure value set by the pressure controller 42, the pore pressure is maintained to be unchanged at the set value;

Performing pressure test after the confining pressure and the hole pressure are applied, finishing the confining pressure and the hole pressure application for 36 hours, wherein the confining pressure change range is within +/-5%, the hole pressure change range is within +/-5%, and the pressure test is qualified, performing the subsequent step 3) if the pressure test is qualified, and re-performing the step 1) after the underground coal gasification pollution evaluation system is overhauled if the pressure test is unqualified;

in the confining pressure and pore pressure application process, confining pressure data, pore pressure data, the volume of the injection medium used in the confining pressure application process, the flow rate of the injection medium used in the confining pressure application process, the volume of the injection medium used in the pore pressure application process and the flow rate of the injection medium used in the pore pressure application process are acquired, and specifically: the confining pressure data monitoring part transmits acquired confining pressure data to the pressure controller 42, the pore pressure data monitoring part transmits the acquired pore pressure data to the pressure controller 42, theservo booster 41 feeds back data such as confining pressure, flow speed, volume and the like of injection media used in the pore pressure applying process to the pressure controller 42, and the pressure controller transmits the confining pressure data, the pore pressure data, the liquid amount data, the flow speed data and the volume data to thecomputer 43 for storage and display;

3) Simulated gasification ofcoal seam 27 is performed:

purging the pipeline throughnitrogen 2 before ignition, and starting subsequent operation after half an hour of purging;

the ignition unit was used to ignite the coal bed 27 at the first ignition position under the injection of the combustion improver (specifically, the heating wire in the well bore 28 at the first ignition position was operated by the ignition controller 9 and continued to be 3 m)³ Small displacement/h oxygen injectionGas is used as combustion improver), when the coal bed 27 is confirmed to be in ignition, a gasifying agent is injected into the coal bed 27 for coal bed gasification, when the calorific value of the synthetic gas generated by the coal bed gasification is reduced to 70% of the initial calorific value, the coal bed ignition is repeatedly carried out at the next ignition position, the gasifying agent is injected into the coal bed 27 for coal bed gasification after the coal bed 27 is in ignition, and the operation of coal bed ignition is completed at the last ignition position, the gasifying agent is injected into the coal bed 27 for coal bed gasification after the coal bed 27 is in ignition, so that the whole coal bed simulated gasification process is completed; the synthesis gas generated in the simulated gasification process of the coal seam 27 enters a synthesis gas treatment unit for treatment and then is discharged, specifically, the generated synthesis gas is respectively removed into solid dust, tar and sulfur-containing toxic gas in the synthesis gas through a cooler 45, a dust remover 46, a coke remover 47 and a sulfur remover 48, and then enters a combustion chamber 50 for combustion treatment of the synthesis gas, and the gas after combustion treatment is discharged; wherein, the synthesis gas processed by the dust remover 46, the coke remover 47 and the sulfur remover 48 is subjected to component analysis and metering to determine the combustible gas components in the synthesis gas and the heat value of the synthesis gas by using a gas detection device 49 every 1-5 minutes;

Wherein, the ignition positions are 2 in total, and are sequentially arranged from the end of the synthesisgas output channel 25 to the end of the gasifyingagent injection channel 10, and the interval between two adjacent ignition positions is 0.8m;

wherein the injected gasifying agent is air gasifying agent, and the flow speed of the air gasifying agent is controlled to be 25m³ /h；

Collecting injection flow rate, pressure and temperature data of the gasifying agent in the simulated gasification process of thecoal seam 27, and performing data collection by using a gas data collection part, a temperature data collection part, a stress strain data collection part and a pore pressure data collection part of the pollution evaluation device, wherein the collected data can be stored and analyzed in a datacollection unit computer 25; according to the detection result of the dissipation of the synthesis gas acquired by the gas data acquisition part, drawing a contour map of the volume and concentration of the dissipation gas, and marking out dissipation boundaries of different gases; the type of the escaping gas comprises CO and CO₂ 、CH₄ And H₂ ；

Monitoring the oxygen concentration during simulated gasification of thecoal seam 27 using the gas data acquisition member, and immediately alerting and stopping the test once the oxygen concentration exceeds the explosion limit;

4)Gasification chamber 30 sewage detection:

after the simulated gasification of thecoal seam 27 is completed, stopping the injection of the gasifying agent, and purging the pollution evaluation device by using thenitrogen bottle 2, on the one hand, discharging the residual synthetic gas in the gasification cavityinner cylinder 16 of the pollution evaluation device, and on the other hand, cooling the temperature of the pollution evaluation device; after nitrogen purging is completed, a sewage detectionunit control valve 51, a high-pressure waterpump control valve 62 and a groundwatertank control valve 60 are opened, coal seam water in agroundwater tank 61 is injected into awell hole 28 through a high-pressure water pump 59 to replace sewage in agasification cavity 30, the pumping pressure is smaller than the pore pressure of the coal seam by 8MPa, the replaced sewage in thegasification cavity 30 is firstly settled by a settlingtank 52 to remove large-size solid residues and coal dust, and waterquality detection equipment 56 performs water quality analysis on the sewage settled by the settlingtank 52 to obtain organic and inorganic pollutant types and content in the underground coal gasification sewage so as to realize pollution evaluation of the underground coal gasification water;

The sewage after sedimentation treatment in thesedimentation tank 52 sequentially enters the primary undergroundwater purification device 53, the secondary undergroundwater purification device 54 and the tertiary undergroundwater purification device 55 for graded sewage purification treatment, and water quality detection is carried out on the sewage after each stage of treatment by using the waterquality detection equipment 56, so that on one hand, experimental support is provided for optimizing the sewage treatment process by simulating the sewage treatment process flow on the other hand after treatment test;

part of the purified sewage enters a sewage recovery tank 58 for centralized treatment, and the other part is pumped into a well hole again through a high-pressure water pump 59 to simulate the ground treatment process;

5) And (3) cutting by using a confining pressure, hole pressure unloading and pollution evaluation device:

after the sewage detection of thegasification cavity 30 is finished, performing confining pressure and pore pressure unloading, and specifically: closing the confiningpressure booster pump 38 and the holepressure booster pump 39, resetting confining pressure and hole pressure to zero through the pressure controller 42, and reducing the pressure value in thehydraulic rod 15 in the pollution evaluation device by theservo booster 41, wherein the acting force of thehydraulic rod 15 is slowly released until the confining pressure value acquired by the confining pressure data monitoring piece is zero, so that the confining pressure is completely unloaded; opening a porepressure relief hole 34 on the pollution evaluation device until the pore pressure value acquired by the pore pressure acquisition part is zero, so as to show that the pore pressure is completely unloaded; cooling the pollution evaluation device for 12 hours after the confining pressure and the hole pressure are unloaded, then opening aleft end cover 31 of the pollution evaluation device and aleft end cover 33 of the gasification cavity, and performing cross-sectional decomposition on the pollution evaluation device;

Thus, the underground coal gasification pollution evaluation is completed.

Example 4

The embodiment provides a method for evaluating underground coal gasification pollution, which is different from the gasification test method provided inembodiment 3 only in that the injected gasifying agent is different in flow velocity, the gasifying agent injected in the embodiment is oxygen-enriched air, the volume concentration of oxygen in the oxygen-enriched air is 40%, and the flow velocity of the gasifying agent is controlled to be 20m³ /h。

Example 5

The embodiment provides a coal underground gasification pollution evaluation method, which is different from the gasification test method provided inembodiment 3 only in that the injected gasifying agents are different, the flow rates of the gasifying agents are different, the injection modes of the gasifying agents are different, the gasifying agents injected in the embodiment are oxygen-enriched air and water vapor, and the two-stage injection is adopted for the injection of the gasifying agents: the first section is filled with oxygen-enriched air, the volume concentration of oxygen in the oxygen-enriched air is 40%, and the flow rate of gasifying agent is controlled to be 20m³ And/h, the stage is mainly coal oxidation combustion exothermic reaction; the second stage is injected with water vapor with the flow rate of 25m³ And/h, the stage mainly comprises water gas reaction and methanation reaction; the two stages are repeated in sequence.

Example 6

The embodiment provides a method for evaluating underground coal gasification pollution, which is different from the gasification test method provided inembodiment 3 only in that the gasifying agents injected are different and the flow rates of the gasifying agents are different, the gasifying agents injected in the embodiment are oxygen-enriched air and water vapor, the volume concentration of oxygen in the oxygen-enriched air is 40%, the mass ratio of the water vapor to the oxygen in the gasifying agents is 3:12:1-4:1, and the flow rate of the gasifying agents is controlled to be 25m³ /h。

Claims (58)

1. The object model experiment device for simulating the real occurrence condition of coal comprises an experiment cabin, wherein the experiment cabin is provided with an experiment cavity;

the experimental cavity comprises an experimental cavity cover and an experimental cavity barrel body which are detachably connected, the experimental cavity barrel body is composed of a barrel bottom and a double-layer barrel body, and the double-layer barrel body comprises an inner barrel and an outer barrel; wherein the inner cylinder is used for loading a sample to be detected;

a cavity is formed between the experiment cavity outer cylinder and the inner cylinder, and a confining pressure applying part is arranged in the cavity and is connected with a confining pressure pipeline;

the wall of the inner cylinder is provided with a hole pressure injection hole which is connected with a hole pressure injection pipeline;

the bottom of the experimental cavity barrel body and/or the experimental cavity cover are provided with experimental injection fluid channels and experimental production fluid channels; the experimental injection fluid channel and the experimental production fluid channel are communicated with the inside of the experimental cavity inner cylinder.

2. The apparatus of claim 1, wherein the confining pressure applying member includes a plurality of hydraulic rods having one ends fixed to an inner wall of the outer cylinder and the other ends acting on an outer wall of the inner cylinder.

3. The device according to claim 2, wherein the hydraulic rod is provided with a hydraulic rod sliding head, the outer wall of the inner cylinder is provided with a hydraulic rod sliding rail, and the hydraulic rod is connected with the outer wall of the inner cylinder in a sliding connection manner by the hydraulic rod sliding head of the hydraulic rod and the hydraulic rod sliding rail of the outer cylinder.

4. A device according to claim 3, wherein the hydraulic rod is provided with a hydraulic rod fixing base, a hydraulic telescopic rod and a hydraulic rod sliding head which are connected in sequence, and the hydraulic rod is fixed on the inner wall of the outer cylinder through the hydraulic rod fixing base.

5. The device of claim 2, wherein the inner cylinder of the experiment cavity is a cuboid enclosed by 4 plates and provided with two open ends; for each plate, wherein only one end of the plate is abutted against the plate surface of the adjacent plate, and the plate surface of the plate is taken as the abutted plate surface of the adjacent plate; each plate is capable of sliding along its abutment plate face.

6. The apparatus of claim 1, wherein,

the experimental cabin is further provided with a confining pressure data monitoring piece which is used for collecting confining pressure data on the inner barrel of the experimental cavity;

the experimental cabin is further provided with a hole pressure data monitoring piece, and the hole pressure data monitoring piece is used for collecting pressure data of the hole pressure filling hole.

7. The apparatus of claim 1, wherein the capsule is further provided with a capsule housing disposed outside the chamber, the capsule housing comprising a detachably connected housing cover and housing barrel.

8. The apparatus of claim 7, wherein the capsule is further provided with refractory bricks disposed in a cavity between the capsule housing and the chamber.

9. The device according to claim 1, wherein the experiment chamber is provided with a data acquisition assembly comprising a gas data acquisition member for acquiring the gases CO, CO in the inner barrel of the experiment chamber₂ 、CH₄ 、H₂ At least one of the escaping concentration and the escaping amount of (a).

10. The apparatus of claim 9, wherein the gas data acquisition member is further configured to acquire an oxygen concentration in the inner barrel of the experiment chamber.

11. The apparatus of claim 9, wherein the gas data collection member comprises a gas detection sensor and a gas detection collector, the gas detection sensor being disposed inside the test chamber and the gas detection collector being disposed outside the test chamber, the gas detection sensor being coupled to the gas detection collector.

12. The apparatus of claim 1, wherein the experimental cabin is further provided with a data acquisition assembly comprising at least one of a temperature data acquisition, a stress strain data acquisition, and a pore pressure data acquisition; the temperature data acquisition part is used for acquiring temperature data of the sample to be detected loaded in the inner barrel of the experiment cavity, the stress strain data acquisition part is used for acquiring stress strain data of the sample to be detected loaded in the inner barrel of the experiment cavity, and the pore pressure data acquisition part is used for acquiring pore pressure of the sample to be detected loaded in the inner barrel of the experiment cavity.

13. The apparatus of claim 12, wherein the temperature data collection member comprises a thermocouple and a temperature collector, the thermocouple being disposed inside the experiment compartment and the temperature collector being disposed outside the experiment compartment, the thermocouple being connected to the temperature collector; the stress-strain data acquisition piece comprises a stress-strain sensor and a stress-strain data acquisition device, wherein the stress-strain sensor is arranged in the experimental cabin, the stress-strain data acquisition device is arranged outside the experimental cabin, and the stress-strain sensor is connected with the stress-strain data acquisition device; the pore pressure data acquisition part comprises a pressure sensor and a pressure acquisition device, wherein the pressure sensor is arranged inside the experimental cabin, the pressure change acquisition device is arranged outside the experimental cabin, and the pressure sensor is connected with the pressure acquisition device.

14. The apparatus of any of claims 9-13, wherein the laboratory is provided with at least one data acquisition routing channel for use with at least one of temperature data acquisition routing, supply force strain data acquisition routing, pore pressure data acquisition routing, and gas data acquisition routing.

15. The apparatus of claim 1, wherein the laboratory cavity is provided with at least two laboratory output fluid channels, wherein at least one laboratory output fluid channel is provided on the same end face of the laboratory cavity as the laboratory injection fluid channel, and a set end face of the at least one laboratory output fluid channel on the laboratory cavity is opposite to a set end face of the laboratory injection fluid channel on the laboratory cavity.

16. The apparatus according to any one of claims 1 to 5, wherein the application of vertical and horizontal forces to the sample to be tested loaded in the inner cartridge of the experimental chamber is achieved by the confining pressure applying member.

17. The apparatus of claim 16, wherein the confining pressure applying members for applying horizontal force and the confining pressure applying members for applying vertical force are respectively connected with different confining pressure injection lines so as to realize respective control of the horizontal force and the vertical force.

18. The device according to claim 1, wherein the application of the hole pressure in the horizontal direction to the sample to be tested loaded in the inner cartridge of the test chamber is achieved by the hole pressure injection hole.

19. The apparatus of claim 18 wherein different height hole pressure injection orifices are connected to different hole pressure injection lines to effect different application of hole pressure to different height hole pressure injection orifices.

20. The apparatus of claim 1, wherein,

the experiment cabin is provided with a hole pressure relief hole;

a check valve is arranged on the hole pressure injection pipeline;

the laboratory cavity is capable of withstanding a pressure of at least 35MPa, a high temperature of at least 1300 ℃ and achieving a seal.

21. Use of the apparatus of any one of claims 1-20 as a pollution evaluation apparatus in the underground gasification pollution evaluation of coal.

22. The underground coal gasification pollution evaluation system comprises a pollution evaluation device, a gasifying agent preparation unit, a confining pressure and pore pressure loading unit, a synthesis gas treatment unit, a sewage detection unit and an ignition unit;

the pollution evaluation device using the device according to any one of claims 1 to 20;

the gasifying agent preparation unit is connected with the experiment injection fluid channel of the pollution evaluation device; the confining pressure and pore pressure loading unit is respectively connected with a confining pressure injection pipeline and a pore pressure injection pipeline of the pollution evaluation device; the synthesis gas treatment unit is connected with the experimental produced fluid channel of the pollution evaluation device; the ignition unit is connected with the gasifying agent preparation unit and the pollution evaluation device and is used for realizing the ignition operation of a sample to be detected loaded in an experimental cavity inner cylinder of the pollution evaluation device; the sewage detection unit is connected with the pollution evaluation device and is used for detecting the water quality of sewage produced in the pollution evaluation device.

23. The underground coal gasification pollution evaluation system of claim 22, wherein the gasifying agent preparation unit is capable of preparing at least one of three gasifying agent types of air, oxygen-enriched air, a mixture of oxygen-enriched air and water vapor.

24. The coal underground gasification pollution evaluation system of claim 23, wherein the gasifying agent preparation unit comprises an oxygen cylinder, an oxygen flow control assembly, a nitrogen cylinder, a nitrogen flow control assembly, a steam generator, a steam flow control assembly, an air compressor, and an air flow control assembly, the oxygen flow control assembly is connected to the oxygen cylinder to control the supply flow of oxygen, the nitrogen flow control assembly is connected to the nitrogen cylinder to control the supply flow of nitrogen, the steam flow control assembly is connected to the steam generator to control the supply flow of steam, and the air flow control assembly is connected to the air compressor to control the supply flow of air.

25. The underground coal gasification pollution evaluation system of claim 24, wherein the gasification agent preparation unit further comprises at least one of a pressure gauge to gauge oxygen supplied by an oxygen cylinder and/or nitrogen supplied by a nitrogen cylinder and/or steam supplied by a steam generator and/or air supplied by an air compressor and/or pressure of the supplied gasification agent, and a temperature gauge to gauge oxygen supplied by an oxygen cylinder and/or nitrogen supplied by a nitrogen cylinder and/or steam supplied by a steam generator and/or air supplied by an air compressor and/or temperature of the supplied gasification agent.

26. The system of claim 22, wherein the sample to be tested loaded in the experimental chamber drum of the pollution evaluation device comprises a coal seam, and the coal seam is pre-formed with wellbores in communication with the experimental injection fluid channel and the experimental production fluid channel, respectively.

27. The coal underground gasification pollution evaluation system of claim 26, wherein a combustible screen or casing is disposed in the wellbore to support the wellbore.

28. The coal underground gasification pollution evaluation system of claim 27, wherein the sample to be tested further comprises a roof and a floor, the roof being positioned above the coal seam and the floor being positioned below the coal seam.

29. The coal underground gasification pollution evaluation system of claim 28, wherein when the experiment chamber is provided with a gas data acquisition member for acquiring gas data of the coal seam and the roof during the experiment, wherein the gas data comprises gas CO, CO₂ 、CH₄ 、H₂ 、O₂ At least one of the escaping concentration and the escaping amount of (a); when the experiment cabin is provided with a temperature data acquisition part, the temperature data acquisition part is used for acquiring an experimentTemperature data of the coal bed, the top plate and the bottom plate in the process; when the experimental cabin is provided with a stress-strain data acquisition part, the experimental cabin is used for acquiring stress-strain data of the top plate; when the experimental cabin is provided with a pore pressure data acquisition part, the pore pressure data acquisition part is used for acquiring pore pressure of the coal bed and/or the roof.

30. The underground coal gasification pollution evaluation system of claim 22, wherein the confining pressure and pore pressure loading unit comprises a servo booster, a pressure controller, a confining pressure booster pump, a pore pressure booster pump, a confining pressure liquid source tank and a pore pressure liquid source tank, the confining pressure liquid source tank and the pore pressure liquid source tank respectively provide injection media for applying confining pressure and injection media for applying pore pressure, the confining pressure liquid source tank, the confining pressure booster pump and the servo booster are sequentially connected, the pore pressure liquid source tank, the pore pressure booster pump and the servo booster are sequentially connected, a fluid outlet of the servo booster is respectively connected with a confining pressure injection pipeline and a pore pressure injection pipeline of the pollution evaluation device, and the pressure controller is connected with the servo booster.

31. The underground coal gasification pollution evaluation system of claim 30, wherein the pollution evaluation device is provided with a confining pressure data monitoring piece and a hole pressure data monitoring piece, the confining pressure data monitoring piece is used for collecting confining pressure data on the inner barrel of the experimental cavity, the hole pressure data monitoring piece is used for collecting pressure data of the hole pressure injection hole, the confining pressure data monitoring piece and the hole pressure data monitoring piece are respectively connected with the pressure controller, and the data collected by the confining pressure data monitoring piece and the hole pressure data monitoring piece are transmitted to the pressure controller.

32. The coal underground gasification pollution evaluation system of claim 30, wherein the confining pressure, pore pressure loading unit further comprises a computer connected to the pressure controller for real-time monitoring, data collection and analysis of confining pressure, pore pressure loading and unloading processes.

33. The coal underground gasification pollution evaluation system of claim 22, wherein the ignition unit comprises an ignition controller as an ignition switch for controlling initial ignition and continuous back ignition operation during the test, and a heating wire disposed in the sample to be tested loaded in the experimental chamber.

34. The underground coal gasification pollution evaluation system of claim 33, wherein one end of the heating wire is arranged in the sample to be detected loaded in the experiment cavity, and the other end of the heating wire is arranged outside the pollution evaluation device, so that the heating wire can be dragged in the sample to be detected loaded in the experiment cavity.

35. The coal underground gasification pollution evaluation system of claim 22, wherein when the experimental cabin of the pollution evaluation device is provided with at least one of a gas data acquisition member, a temperature data acquisition member, a stress-strain data acquisition member, and a pore pressure data acquisition member, the coal underground gasification pollution evaluation system further comprises a data acquisition unit comprising a computer connected to at least one of the gas data acquisition member, the temperature data acquisition member, the stress-strain data acquisition member, and the pore pressure data acquisition member for storing and analyzing data acquired by the data acquisition member connected to the computer.

36. The coal underground gasification pollution evaluation system of claim 22, wherein the syngas treatment unit comprises a dust remover, a coke remover, a sulfur remover, and a combustion chamber, wherein the dust remover, the coke remover, and the sulfur remover are all disposed before the combustion chamber; the dust remover is used for removing solid dust in the synthesis gas discharged from the experimental fluid output channel, the decoking device is used for removing tar in the synthesis gas, the sulfur removing device is used for removing sulfur-containing toxic gas in the synthesis gas, and the combustion chamber is used for carrying out combustion treatment on the synthesis gas.

37. The coal underground gasification pollution evaluation system of claim 36, wherein the syngas treatment unit further comprises a gas detection device to analyze and meter the composition of the syngas after the dust collector, the char remover, and the sulfur remover.

38. The coal underground gasification pollution evaluation system of claim 36, wherein the syngas treatment unit further comprises a cooler disposed before the dust remover, the char remover, and the sulfur remover.

39. The coal underground gasification pollution evaluation system of claim 22, wherein the wastewater detection unit comprises a water injection device connected to the experimental injection fluid channel of the pollution evaluation device for injecting water into the pollution evaluation device to displace wastewater in the experimental chamber inner barrel, and a water quality detection device for detecting the quality of wastewater discharged in the experimental chamber inner barrel of the pollution evaluation device.

40. The coal underground gasification pollution evaluation system of claim 39, wherein the wastewater detection unit further comprises a settling tank coupled to the experimentally produced fluid path of the pollution evaluation device, and the water quality detection device is coupled to the settling tank for detecting wastewater after settling in the settling tank.

41. The coal gasification pollution evaluation system of claim 40, wherein the wastewater detection unit comprises a wastewater purification device, the wastewater purification device is connected to the water outlet of the settling tank, and the water quality detection device is further connected to the wastewater purification device to detect the wastewater quality during and after the wastewater purification by the wastewater purification device.

42. The coal gasification pollution evaluation system of claim 41, wherein the wastewater purification device comprises a primary groundwater purification device, a secondary groundwater purification device, and a tertiary groundwater purification device, and the water quality detection device is connected to the primary groundwater purification device, the secondary groundwater purification device, and the tertiary groundwater purification device, respectively, to detect the quality of wastewater after the primary groundwater purification device, the secondary groundwater purification device, and the tertiary groundwater purification device have been subjected to wastewater purification.

43. A method of evaluating underground coal gasification pollution using the underground coal gasification pollution evaluation system of any one of claims 22-42, the method comprising:

1) Preparing a top plate, a bottom plate and a coal bed for gasification test, setting heating wires in prefabricated wellholes according to the well type prefabricated wellholes which are simulated in the coal bed as required and according to the initial ignition position, filling the bottom plate, the coal bed and the top plate into an experimental cavity inner barrel from bottom to top in the sequence of the bottom plate, the coal bed and the top plate, and connecting the underground coal gasification pollution evaluation system;

2) Performing confining pressure and pore pressure application according to confining pressure and pore pressure values of the coal seam in the simulation area;

3) Performing coal seam simulated gasification: under the condition of injecting combustion improver into the coal bed, using an ignition unit to ignite the coal bed at an ignition position, and injecting gasifying agent into the coal bed to gasify the coal bed after the coal bed is in place, so as to complete the simulated gasification process of the coal bed; the synthesis gas generated in the coal seam simulated gasification process enters a synthesis gas unit for treatment and then is discharged;

4) Gasification cavity sewage detection: injecting water into the experiment cavity to displace the sewage in the gasification cavity, and detecting the water quality of the displaced sewage to realize water pollution evaluation;

Thus, the underground coal gasification pollution evaluation is completed.

44. The method for evaluating underground coal gasification pollution according to claim 43, wherein the well to be simulated is a U-shaped horizontal well, a single-hole well is prefabricated in the coal seam, and the experimental injection fluid channel and the experimental production fluid channel are respectively arranged at two corresponding ends of the experimental cavity inner barrel.

45. The method of evaluating underground coal gasification pollution of claim 44, wherein a combustible screen and/or casing is run into the preformed wellbore in the coal seam to support the wellbore.

46. The method for evaluating underground gasification pollution of coal according to claim 43,

confining pressure application includes applying vertical and horizontal forces; the vertical acting force and the horizontal acting force are used for simulating the pressure of the overlying stratum and the horizontal main stress;

pore pressure application includes applying pore pressure to the coal seam.

47. The method for evaluating underground coal gasification pollution of claim 43, wherein said performing coal seam simulated gasification comprises: igniting the coal bed at a first ignition position by using an ignition unit under the condition of injecting a combustion improver into the coal bed, injecting a gasifying agent into the coal bed for coal bed gasification after the coal bed is in a burning position, and repeatedly igniting and gasifying the coal bed at a next ignition position when the heat value of the synthetic gas generated by the coal bed gasification is reduced to 65-75% of the initial heat value until the final ignition position finishes the coal bed ignition and gasification, thereby finishing the whole coal bed simulated gasification process; the synthesis gas generated in the coal seam simulated gasification process enters a synthesis gas unit for treatment and then is discharged; and (3) the synthesis gas generated in the coal seam simulated gasification process enters a synthesis gas unit for treatment and then is discharged.

48. The method for evaluating underground coal gasification pollution of claim 47, wherein the ignition location is located sequentially from a location remote from the location where gasifying agent is injected to a location near the location where gasifying agent is injected.

49. The method for evaluating underground coal gasification pollution of claim 43, wherein said gasifying agent comprises: at least one of an air gasifying agent, an oxygen-enriched air gasifying agent and an oxygen-enriched air+water vapor gasifying agent.

50. The method for evaluating underground coal gasification pollution of claim 49, wherein when the gasifying agent is oxygen-enriched air+steam gasifying agent, the gasifying agent is injected in two stages or in one stage; wherein,,

the two-stage injection includes: the first section is filled with oxygen-enriched air, the volume concentration of oxygen in the oxygen-enriched air is 21% -50%, and the flow velocity of the oxygen-enriched air is 0-30m³ /h; the second stage is injected with water vapor with the flow rate of 0-30m³ /h; the two stages are repeated in turn;

the one-stage injection is to inject oxygen-enriched air and water vapor into the coal seam at the same time, wherein the volume concentration of oxygen in the oxygen-enriched air is 21% -50%, the mass ratio of the water vapor to the oxygen in the gasifying agent is 2:1-4:1, and the flow rate of the gasifying agent is 0-30m³ /h。

51. The method for evaluating underground coal gasification pollution according to claim 43, wherein the mounting holes of the gas data collection material are formed in the top plate and/or bottom plate for evaluation of gasification pollution and/or the coal bed, and the gas data collection material is mounted in the top plate and/or bottom plate for evaluation of gasification pollution and/or the coal bed.

52. The method for evaluating underground coal gasification pollution of claim 51, wherein during step 3) coal seam simulated gasification, a gas data collection element is used for syngas emissions detection.

53. The method for evaluating underground coal gasification pollution of claim 51, wherein the gas data collection element is used to monitor the oxygen concentration during step 3) of the simulated gasification of the coal seam.

54. The method for evaluating underground gasification pollution of coal according to claim 43,

prefabricating mounting holes of a temperature data acquisition piece, a stress strain data acquisition piece and a pore pressure data acquisition piece in a top plate and/or a bottom plate and/or a coal bed for gasification experiments, and mounting the temperature data acquisition piece, the stress strain data acquisition piece and the pore pressure data acquisition piece in the top plate and/or the bottom plate and/or the coal bed for gasification experiments;

collecting at least one of confining pressure data, pore pressure data, the volume of an injection medium used in a confining pressure application process, the flow rate of the injection medium used in the confining pressure application process, the volume of the injection medium used in the pore pressure application process and the flow rate of the injection medium used in the pore pressure application process;

In step 3) the gasification agent injection flow rate, pressure and temperature data are collected.

55. The method of evaluating underground coal gasification pollution of claim 54, wherein in step 3) the simulated gasification of the coal seam, the data is collected using a temperature data collection element, a stress strain data collection element, and a pore pressure data collection element.

56. The method for evaluating underground gasification pollution of coal as recited in claim 43, wherein the gasification chamber wastewater detection further comprises purifying the displaced wastewater and detecting the quality of the wastewater during and after the purification.

57. The method for evaluating underground gasification pollution of coal according to claim 43,

using a gas chromatograph in the synthesis gas treatment unit to analyze and meter the components of the synthesis gas and determine the combustible gas components in the synthesis gas and the calorific value of the synthesis gas;

the synthetic gas generated in the coal seam simulated gasification process enters a synthetic gas unit for treatment, and the method comprises the following steps: the generated synthesis gas is subjected to dust remover, decoking device and sulfur remover to remove solid dust, tar and sulfur-containing toxic gas in the synthesis gas respectively, and then enters a combustion chamber to carry out combustion treatment on the synthesis gas, and the gas after the combustion treatment is discharged.

58. The method for evaluating underground coal gasification pollution according to claim 43, wherein sand is filled between the coal bed and the inner wall of the inner cylinder of the experimental chamber.

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