CN113445974A - Device and application, and coal underground gasification pollution evaluation system and method - Google Patents

Abstract

The invention provides a device and application thereof, and a coal underground gasification pollution evaluation system and method. The device comprises an experiment chamber, wherein the experiment chamber 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 comprises 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 barrel and the outer wall of the inner barrel, a confining pressure applying component is arranged in the cavity, and the confining pressure applying component is connected with a confining pressure pipeline; the wall of the inner cylinder is provided with a pore pressure injection hole, and the pore pressure injection hole is connected with a pore pressure pipeline; an experiment fluid injection channel and an experiment fluid output channel are arranged on the end cover of the experiment cavity and/or the barrel bottom of the barrel body of the experiment cavity; the experiment fluid injection channel and the experiment fluid output channel are communicated with the inner part of the experiment cavity barrel. The device can realize that the true occurrence condition of simulation coal specifically can simulate confined pressure, the pore pressure in dark coal seam. The device is matched with other equipment to realize the coal underground gasification pollution evaluation considering the real occurrence conditions of the coal bed.

Description

Device and application, and coal underground 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 thereof, and an underground coal gasification pollution evaluation system and method.

Background

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

The risk of contamination of underground coal gasification is an important reason that limits the development of this technology. The coal gasification process can generate organic pollutants and inorganic pollutants, wherein the organic pollutants mainly comprise phenols, benzene and derivatives thereof and polycyclic aromatic hydrocarbons, the inorganic pollutants mainly comprise heavy metals (zinc, lead, cadmium and arsenic), ammonia salts, sulfates and cyanides, and the pollutants exist in synthesis gas, residues and semicoke in gaseous and solid forms. Because coal underground gasification runs in a high-temperature and high-pressure underground closed environment, synthetic gas moved through formation pores and cracks can pollute formation water or surrounding formations; after gasification, coal bed water enters a gasification cavity and then soaks solid residues and semicoke, so that pollutants enter stratum water and can cause great threat to an underground water layer. Compared with coal ground gasification, coal underground gasification has hysteresis quality in data transmission and operation actions, once the coal underground gasification causes environmental pollution, effective remediation is difficult, and even project shutdown is caused when the problem is serious. Therefore, the method has great significance for underground coal gasification construction and later-period environmental management by mastering the escape range of the synthesis gas and the leaching and migration rules of solid pollutants in the underground coal gasification process.

The coal underground gasification water pollution treatment and restoration technology comprises a pumping ground treatment technology, a chemical oxidation technology, a biodegradation technology and the like, but the patent and research on a synthetic gas dissipation and underground water pollution evaluation test device are less. CN104297186A proposes a comprehensive experiment system for coal underground gasification pollution evaluation and underground pollution purification and remediation, but the experiment system cannot evaluate the escape condition of synthetic gas and simulate the occurrence state of a coal bed and confined water. At present, the following problems exist in the aspects of a device for evaluating the dissipation of coal underground gasification synthesis gas and the pollution of underground water: 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 types and process parameters of the gasification agent cannot be simulated; 3. the method can not detect the escape of the synthesis gas and calibrate the escape boundary; 4. the test device can not realize the sewage detection and treatment function and can not provide support for the optimization of the underground coal gasification pollution treatment scheme and the optimization of process parameters.

Disclosure of Invention

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

In order to achieve the above object, the present invention provides an apparatus, which comprises an experiment chamber, wherein the experiment chamber 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; the inner cylinder is used for loading a sample to be detected;

a cavity is formed between the inner wall of the outer barrel and the outer wall of the inner barrel, a confining pressure applying component is arranged in the cavity, and the confining pressure applying component 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 inner cylinder of the experimental cavity so as to realize that the confining pressure is applied to the sample to be detected loaded in the inner cylinder of the experimental cavity;

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

an experiment injection fluid channel and an experiment output fluid channel are arranged on the bottom of the experiment cavity cover and/or the experiment cavity barrel body; the experiment injection fluid channel and the experiment production fluid channel are communicated with the inside of the experiment cavity inner cylinder.

In the device, the barrel bottom and/or the experimental cavity end cover of the experimental cavity barrel body are/is provided with an experimental fluid injection channel and an experimental fluid output channel, and specifically, the barrel bottom of the experimental cavity barrel body can be simultaneously provided with the experimental fluid injection channel and the experimental fluid output channel, and at the moment, 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 end cover of the experimental cavity can be simultaneously provided with an experimental fluid injection channel and an experimental fluid output channel, and the bottom of the experimental cavity barrel body can be provided with or without the experimental fluid injection channel and/or the experimental fluid output channel; an experiment fluid injection channel can be arranged on the end cover of the experiment cavity, and an experiment fluid output channel is arranged on the bottom of the experiment cavity barrel body; an experiment fluid output channel can be arranged on the end cover of the experiment cavity, and an experiment fluid injection channel is arranged on the bottom of the barrel body of the experiment cavity.

In the above device, preferably, the confining pressure applying component includes a plurality of hydraulic rods, one end of each hydraulic rod is fixed on the inner wall of the outer cylinder, and the other end of each hydraulic rod acts on the outer wall of the inner cylinder of the experimental 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 connection between the hydraulic rod and the outer wall of the inner cylinder is realized in a manner that the hydraulic rod sliding head of the hydraulic rod is in sliding connection with 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 connected in sequence, and the hydraulic rod is fixed on the inner wall of the outer barrel through the hydraulic rod fixing base. In a preferred embodiment, the inner cylinder of the experimental cavity is a cuboid (including a cube) which is enclosed by 4 plates and is open at two ends; for each plate, only one end of the plate abuts against the plate surface of one plate adjacent to the plate, and the plate surface of the plate is used as an abutting plate surface of the other plate adjacent to the plate; each panel is able to slide along its abutting panel surface; the space thus formed by the plates can be reduced or enlarged in the horizontal and/or vertical direction. In the preferred scheme, the hydraulic rod adopts the design mode that the outer wall is fixed, and the inner wall adopts the sliding rail, so that the problem that the inner wall plate can move on the plumb surface when confining pressure is applied in a single direction is solved.

In the above device, preferably, the experimental chamber is capable of withstanding and sealing at least 1300 ℃ and at least 35 MPa; more preferably, the inner barrel, the outer barrel, the experimental cavity cover and the barrel bottom of the experimental cavity barrel body are 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 disposed on the pore pressure injection line to prevent backflow of the pore pressure injection medium.

In the above device, preferably, the experiment chamber is further provided with a confining pressure data monitoring part, the confining pressure data monitoring part is used for collecting confining pressure data on the inner cylinder of the experiment chamber, and the confining pressure data monitoring part preferably uses a stress sensor which is arranged on the wall of the inner cylinder of the experiment chamber.

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

In the above device, preferably, the experiment chamber is further provided with an experiment chamber housing, the experiment chamber housing is arranged outside the experiment cavity, the experiment chamber housing comprises a housing cover and a housing barrel body which are detachably connected, and the housing cover and the housing barrel body can be detachably connected together through at least two sealing bolts; more preferably, the experiment chamber is further provided with a refractory brick, and the refractory brick is arranged in a cavity between the experiment chamber shell and the experiment chamber. 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 into an experimental cavity shell barrel body through the barrel wall and the barrel bottom, and can also be detachably connected together 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 a barrel body of the experimental cavity shell.

In the above apparatus, preferably, the experiment chamber is providedThe device comprises a data acquisition assembly, wherein the data acquisition assembly comprises a gas data acquisition part for acquiring CO and CO in a cylinder in a laboratory cavity₂、CH₄、H₂At least one of a dissipation concentration and a dissipation amount of (a); more preferably, the gas data acquisition element is further used for acquiring the oxygen concentration in the inner barrel of the experiment cavity, and once the oxygen concentration exceeds the explosion limit, alarming and stopping the experiment. In a specific embodiment, the gas data acquisition part comprises a gas detection sensor and a gas detection collector, the gas detection sensor is arranged inside the experiment chamber, the gas detection collector is arranged outside the experiment chamber, and the gas detection sensor is connected with the gas detection collector. In one embodiment, 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, according to the testing requirements of the gas data.

In the above device, preferably, the experiment chamber is provided with a data acquisition assembly, and the data acquisition assembly comprises at least one of a temperature data acquisition part, a stress-strain data acquisition part and a pore pressure data acquisition part; the temperature data acquisition part is used for acquiring temperature data of a sample to be detected loaded in the tube in the experimental cavity, the stress-strain data acquisition part is used for acquiring stress-strain data of the sample to be detected loaded in the tube in the experimental cavity, and the pore pressure data acquisition part is used for acquiring pore pressure of the sample to be detected loaded in the tube in the experimental cavity. In one embodiment, the temperature data collection element comprises a thermocouple and a temperature collector, the thermocouple is disposed inside the test chamber and the temperature collector is disposed outside the test chamber, and the thermocouple is connected to the temperature collector. In a specific embodiment, the stress-strain data acquisition element comprises a stress-strain sensor and a stress-strain data acquisition unit, the stress-strain sensor is arranged inside the experiment chamber, the stress-strain data acquisition unit is arranged outside the experiment chamber, and the stress-strain sensor is connected with the stress-strain data acquisition unit. In one embodiment, the pore pressure data acquisition element comprises a pressure sensor and a pressure collector, the pressure sensor is arranged inside the test chamber, the pressure collector is arranged outside the test chamber, and the pressure sensor is connected with the pressure collector. In one embodiment, several thermocouples are placed in the sample to be tested from top to bottom, from left to right, and from front to back, as required for temperature testing. In another embodiment, according to the requirement of the stress-strain test, a plurality of stress-strain sensors are arranged on 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 requirement of pore pressure test, a plurality of pore pressure sensors are arranged on 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 device, preferably, the experimental chamber is provided with at least one data collecting wiring channel for at least one of wiring of the temperature data collecting member, wiring of the supply force strain data collecting member, wiring of the pore pressure data collecting member and wiring of the gas data collecting member. In one embodiment, the temperature data acquisition element comprises a thermocouple and a temperature collector, the thermocouple is arranged inside the experiment chamber, the temperature collector is arranged outside the experiment chamber, and the thermocouple and the temperature collector are in line connection through a data wiring channel. In a specific embodiment, the stress-strain data acquisition element preferably includes a stress-strain sensor and a stress-strain data acquisition unit, the stress-strain sensor is disposed inside the experiment chamber, the stress-strain data acquisition unit is disposed outside the experiment chamber, and the stress-strain sensor and the stress-strain data acquisition unit are connected by a data wiring channel. In a specific embodiment, the pore pressure data acquisition element comprises a pressure sensor and a pressure collector, the pressure sensor is arranged inside the experiment chamber, the pressure collector is arranged outside the experiment chamber, and the pressure sensor and the pressure collector 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 collector, the gas detection sensor is arranged inside the experiment chamber, the gas detection collector is arranged outside the experiment chamber, and the gas detection sensor and the gas detection collector are connected by a data wiring channel.

In the above device, preferably, the confining pressure applying component can apply a vertical acting force and a horizontal acting force to the sample to be tested loaded in the tube in the laboratory cavity. More preferably, the confining pressure applying component for applying horizontal acting force and the confining pressure applying component for applying vertical acting force are respectively connected with different confining pressure injection pipelines so as to realize the respective control of the magnitude of the horizontal acting force and the magnitude of the vertical acting force.

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

In the device, preferably, the hole pressure injection hole is arranged in the wall of the inner cylinder of the laboratory cavity, and the hole pressure can be applied to the sample to be tested loaded in the inner cylinder of the laboratory cavity in the horizontal direction. More preferably, the pore pressure injection holes with different heights are connected with different pore pressure injection pipelines so as to apply different pore pressures to the pore pressure injection holes with different heights, and the pore pressure change along with the depth can be simulated. In a specific embodiment, the inner experiment cavity barrel is a barrel with left and right ends opened, and the front wall and the rear wall of the inner experiment cavity barrel are both provided with hole pressure injection holes.

In the above apparatus, preferably, the laboratory cover and the laboratory bucket are detachably connected together by at least two sealing bolts.

In the above apparatus, preferably, the outer wall of the experiment chamber is rectangular parallelepiped.

In the above apparatus, preferably, the pressure injection holes are arranged at equal intervals on the wall of the inner cylinder of the laboratory chamber. Can arrange according to certain rule equidistance usually, in a specific embodiment, the shape of laboratory cavity inner tube is the cuboid of controlling both ends opening, and the antetheca, the back wall of laboratory cavity inner tube set up the pore pressure filling hole for b equidistant according to horizontal distance for a longitudinal distance.

In the above device, preferably, the test chamber is provided with an orifice 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 together through the double-layer barrel body and the barrel bottom to form the experimental cavity barrel body.

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

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

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

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

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

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

In the above system for evaluating underground coal gasification pollution, preferably, the gasification agent preparation unit is capable of preparing at least one of three types of gasification agents, namely air, oxygen-enriched air and a mixed gas of oxygen-enriched air and water vapor; more preferably, 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, wherein the oxygen flow control assembly is connected with the oxygen cylinder to control the supply flow of oxygen, the nitrogen flow control assembly is connected with the nitrogen cylinder 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, wherein the oxygen flow control assembly, the nitrogen flow control assembly, the steam flow control assembly and the air flow control assembly can all comprise a gas flow meter and a valve with controllable opening degree; further preferably, the gasifying agent preparation unit further comprises at least one of a pressure gauge for measuring the pressure of oxygen supplied from the oxygen cylinder and/or nitrogen supplied from the nitrogen cylinder and/or steam supplied from the steam generator and/or air supplied from the air compressor and/or the gasifying agent supplied, and a thermometer for measuring the temperature of oxygen supplied from the oxygen cylinder and/or nitrogen supplied from the nitrogen cylinder and/or steam supplied from the steam generator and/or air supplied from the air compressor and/or the gasifying agent supplied, wherein the thermometer is preferably a thermocouple thermometer.

In the above coal underground gasification pollution evaluation system, preferably, the pollution evaluation device is loaded in a laboratory chamber cylinderThe sample to be detected comprises a coal bed, a borehole is prefabricated in the coal bed, and the borehole is respectively communicated with the experiment injection fluid channel and the experiment output fluid channel; more preferably, the wellbore is provided with a combustible screen or casing for supporting the wellbore. Preferably, the sample to be tested further comprises a top plate and a bottom plate, wherein the top plate is arranged above the coal seam, and the bottom plate is arranged below the coal seam. In one embodiment, the coal seam is comprised of cubic coal blocks arranged in series. In one embodiment, the top and bottom plates are arranged to meet similar criteria (typically the prepared top and bottom plates are identical to the actual formation top and bottom plates in rock mechanical properties). In a specific embodiment, the thicknesses of the top plate and the bottom plate meet similar criteria, the thickness of the top plate in the test system is 1/5-1/40 larger than that of the top plate of the real stratum, and the thickness of the bottom plate in the test system is 1/5-1/40 larger than that of the bottom plate of the real stratum. Further preferably, when the experiment chamber is provided with the gas data acquisition part, the gas data acquisition part is used for acquiring gas data of a coal bed and a roof in the experiment process, wherein the gas data comprises CO and CO₂、CH₄、H₂、O₂At least one of the dissipation concentration and the dissipation amount (preferably further including the oxygen concentration); in one embodiment, a plurality of groups of gas detection sensors are arranged in a sample to be detected at equal intervals along the extension direction of a borehole, each group of gas detection sensors is arranged on a section of the sample to be detected, which is perpendicular to the extension direction of the borehole, and each group of gas detection sensors comprises a plurality of gas detection sensors; wherein, on the setting cross-section of each group of gas detection sensors, a plurality of thermocouples are arranged along the longitudinal direction from the top plate to the borehole, and a plurality of thermocouples are arranged along the horizontal direction. Further preferably, when the experiment chamber is provided with the 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 experiment process; in a specific embodiment, a plurality of groups of thermocouples are arranged in a sample to be measured at equal intervals along the extension direction of a borehole, each group of thermocouples is arranged on a section, perpendicular to the extension direction of the borehole, of the sample to be measured, and each group of thermocouples is provided with a plurality of thermocouples; wherein, on the setting section of each group of thermocouples, a plurality of rows of thermoelectricity are arranged along the longitudinal direction from the top plate to the bottom plateThe row spacing between adjacent thermocouples is smaller even and closer to the borehole, and the spacing between adjacent thermocouples is smaller closer to the borehole in each row of thermocouples. Further preferably, when the experiment chamber is provided with a stress-strain data acquisition part, the stress-strain data acquisition part is used for acquiring stress-strain data of the top plate; in a specific embodiment, the stress-strain sensors are arranged on the top of the coal seam and/or the top plate and are provided with a plurality of groups of stress-strain sensors at equal intervals along the extension direction of the borehole, each group of stress-strain sensors is arranged on a section, perpendicular to the extension direction of the borehole, of the sample to be measured, and each group of stress-strain sensors is provided with a plurality of stress-strain sensors. Further preferably, when the experiment chamber is provided with a pore pressure data acquisition part, the pore pressure data acquisition part is used for acquiring the pore pressure of the coal bed and/or the top plate; in one embodiment, the pore pressure sensors are arranged on the coal bed and/or the top plate and are arranged at equal intervals along the borehole extension direction, each group of pore pressure sensors are arranged on a section of the sample to be detected, the section is perpendicular to the borehole extension direction, and each group of pore pressure sensors is provided with a plurality of pore pressure sensors.

In the above coal underground gasification pollution evaluation system, preferably, 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, enclose and press liquid source jar and hole pressure liquid source jar to provide respectively and apply the used injection medium of confining pressure and apply the used injection medium of hole pressure, enclose and press the liquid source jar, enclose and press the booster pump, servo booster connects gradually, hole pressure liquid source jar, hole pressure booster pump is connected, servo booster connects gradually, thereby servo booster's fluid outlet respectively with pollute evaluation device's confined pressure injection pipeline and hole pressure injection pipeline connection realize confining pressure, hole pressure loading unit respectively with pollute evaluation device's confined pressure injection pipeline and hole pressure injection pipeline connection, pressure controller is connected with servo booster and is used for controlling servo booster's pressure and applys the control. The injection medium provided by the confining pressure liquid source tank is subjected to primary pressurization through a confining pressure booster pump, then is subjected to secondary pressurization through a servo booster, and then flows into a confining pressure applying component of the pollution evaluation device through a confining pressure injection pipeline to provide pressure for the confining pressure applying component of the pollution evaluation device, wherein the servo booster is used for carrying out secondary pressurization on the injection medium according to the pressure value in the pressure controller and achieving a set value; and the injection medium provided by the pore pressure liquid source tank is subjected to primary pressurization through the pore pressure booster pump, then is subjected to secondary pressurization through the servo booster, and then flows into the pore pressure injection hole of the pollution evaluation device through the pore pressure injection pipeline to provide pressure for the pore pressure injection hole of the pollution evaluation device, wherein the servo booster 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. More preferably, the pollution evaluation device is provided with a confining pressure data monitoring piece and a pore pressure data monitoring piece, the confining pressure data monitoring piece is used for acquiring confining pressure data on a cylinder in a laboratory cavity, the pore pressure data monitoring piece is used for acquiring pressure data of a pore pressure injection hole, the confining pressure data monitoring piece and the pore pressure data monitoring piece are respectively connected with the pressure controller, and the data acquired by the confining pressure data monitoring piece and the pore pressure data monitoring piece are transmitted to the pressure controller; wherein, the confining pressure data monitoring part preferably uses stress sensor and this stress sensor sets up on the section of thick bamboo wall of experiment chamber inner tube, and the pore pressure data monitoring part preferably uses pressure sensor and this pressure sensor is connected with the pore pressure filling hole. The confining pressure and pore pressure loading unit preferably further comprises a computer, and the computer is connected with the pressure controller and is used for monitoring, acquiring and analyzing the confining pressure and pore pressure loading and unloading processes in real time.

In the above coal underground gasification pollution evaluation system, preferably, the ignition unit includes an ignition controller and an electric heating wire, the ignition controller is used as an ignition switch and is used for controlling initial ignition and continuous back ignition operation in the test process, and the electric heating wire is arranged in a sample to be tested loaded in the experimental cavity and is used for providing the temperature required by coal combustion in the test process, and is matched with a 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. Different ignition positions can be simulated by dragging the heating wire, so that the continuous retreating process of the controlled injection point is simulated.

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

In the above coal underground gasification pollution evaluation system, preferably, the syngas 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 disposed before the combustion chamber, i.e., the syngas 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 synthetic gas discharged from the experimental fluid output channel, the coke remover is used for removing tar in the synthetic gas, the sulfur remover is used for removing sulfur-containing toxic gas in the synthetic gas, and the combustion chamber is used for carrying out combustion treatment on the synthetic gas. More preferably, the synthesis gas treatment unit further comprises a gas detection device, wherein the gas detection device is used for analyzing and metering the components of the synthesis gas treated by the dust remover, the coke remover and the sulfur remover; the gas detection equipment can be a gas chromatograph. The synthesis gas treatment unit preferably comprises a cooler, wherein the cooler is arranged before the dust remover, the decoking device and the sulfur remover and used for cooling the synthesis gas discharged from the experimental fluid output channel and avoiding the high-temperature gas from damaging the subsequent test device.

In the above-mentioned coal underground gasification pollution evaluation system, preferably, the sewage detection unit includes water injection equipment and water quality testing equipment, the water injection equipment with the experiment injection fluid passageway of pollution evaluation device is connected for to thereby the pollution evaluation device injected water displaces the sewage in the experiment chamber inner tube, water quality testing equipment is used for detecting the quality of water of the sewage that discharges in the experiment chamber inner tube of pollution evaluation device. More preferably, the sewage detection unit further includes the gunbarrel, the gunbarrel with the experiment of pollution evaluation device is produced fluid passage and is connected and is used for deposiing solid residue, granule such as buggy in the sewage, thereby water quality testing equipment is connected with the gunbarrel and is detected the sewage after deposiing the gunbarrel and realize that water quality testing equipment detects the quality of water of exhaust sewage in the experiment chamber inner tube of pollution evaluation device. Further preferably, the sewage detection unit includes sewage purification equipment, sewage purification equipment is connected with the water outlet of gunbarrel for carry out purification treatment to sewage, water quality testing equipment further is connected with sewage purification equipment, water quality testing equipment further is used for detecting sewage purification equipment and carries out the sewage purification in-process and the sewage quality after the sewage purification. Preferably, the sewage purification equipment comprises a first-level underground water purification device, a second-level underground water purification device and a third-level underground water purification device, and the water quality detection equipment is respectively connected with the first-level underground water purification device, the second-level underground water purification device and the third-level underground water purification device and is used for detecting the quality of sewage purified by the first-level underground water purification device, the second-level underground water purification device and the third-level underground water purification device; the sewage purification equipment purifies and treats the underground sewage in stages according to test requirements, and the purified underground sewage is detected and evaluated through the water quality detection equipment. The water quality detection equipment preferably comprises an organic pollutant detection device and an inorganic pollutant detection device, the organic pollutant detection device can select a gas chromatography-mass spectrometry (GC-MS) instrument, and the inorganic pollutant detection device can select a plasma emission mass spectrometry (ICP-MS) instrument. Underground sewage can enter a sewage recovery tank for recovery after three-stage purification, and can also be repeatedly used as injection water for displacing sewage in an inner cylinder of an experimental cavity in a subsequent experiment so as to simulate the ground treatment process of pumping underground water out. The sewage purification equipment in the unit can also simulate the sewage treatment technologies such as chemical oxidation technology, biodegradation technology and the like. In the coal underground gasification pollution evaluation system, all pressure-bearing connecting pipelines preferably use high-pressure-resisting pipelines which can bear the pressure of at least 35MPa and can realize good sealing.

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

1) preparing a top plate, a bottom plate and a coal bed for gasification pollution evaluation, arranging an electric heating wire in a well-shaped prefabricated well hole simulated in the coal bed according to needs and a primary ignition position, filling the bottom plate, the coal bed and the top plate into an inner cylinder of an experimental cavity from bottom to top in the sequence of bottom plate-coal bed-top plate in the inner cylinder of the experimental cavity, and connecting the underground coal gasification pollution evaluation system;

2) applying confining pressure and pore pressure according to confining pressure and pore pressure values of the coal seam in the simulated area;

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

4) and (3) detecting sewage in the gasification cavity: injecting water into the experimental cavity to displace sewage in the gasification cavity, and performing water quality detection on the displaced sewage to realize water pollution evaluation;

thereby completing the coal underground gasification pollution evaluation.

In the method for evaluating underground coal gasification pollution, preferably, before preparing a top plate, a coal bed and a bottom plate for gasification pollution evaluation, a rock mechanical test of a real top plate and a real bottom plate of the coal bed in a simulation area is carried out, and then the top plate and the bottom plate for the gasification test are prepared according to the measured mechanical properties and the material similarity principle;

in the method for evaluating underground coal gasification pollution, preferably, the coal seam for gasification experiments is prepared by using coal blocks obtained from coal seams in a simulated region. More preferably, coal dust and clay are smeared among coal blocks of the coal bed for preparing the gasification experiment, so that the integrity of the coal bed is ensured. In one embodiment, coal blocks obtained from a simulated regional coal seam are cut into regular cubic coal blocks, and the coal blocks are combined to form a coal seam for a gasification experiment.

In the coal underground gasification pollution evaluation method, preferably, the joints of the coal seam, the top plate and the bottom plate are coated with coal powder and clay, so that the sealing performance and integrity of the coal seam, the top plate and the bottom plate are ensured.

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

In the underground coal gasification pollution evaluation method, preferably, mounting holes of the gas data acquisition member are prefabricated in the roof and/or the floor and/or the coal seam for gasification pollution evaluation according to the gasification pollution evaluation requirement, and the gas data acquisition member is mounted in the roof and/or the floor and/or the coal seam for gasification pollution evaluation. More preferably, in the coal seam simulation gasification process in the step 3), the gas data acquisition part is used for detecting the loss of the synthesis gas. The collected data can be stored and analyzed in a data collection unit (e.g., a computer). Further preferably, according to the detection result of the synthesis gas loss, a contour map of the volume and/or concentration of the released gas is drawn, and the loss boundaries of different gases are calibrated; the types of the escaped gas comprise CO and CO₂、CH₄And H₂At least one of (1).

In the method for evaluating pollution of underground coal gasification, preferably, in the step 3) of coal bed simulation gasification, the gas data acquisition part is used for monitoring the oxygen concentration, and once the oxygen concentration exceeds the explosion limit, the alarm is immediately sent out and the test is stopped.

In the method for evaluating underground coal gasification pollution, preferably, mounting holes for the temperature data acquisition member, the stress strain data acquisition member and the pore pressure data acquisition member are prefabricated in the roof and/or the floor and/or the coal seam for evaluating gasification pollution according to the evaluation requirement of gasification pollution, and the temperature data acquisition member, the stress strain data acquisition member and the pore pressure data acquisition member are mounted in the roof and/or the floor and/or the coal seam for a gasification experiment. More preferably, in the coal seam simulation gasification process in the step 3), the temperature data acquisition part, the stress strain data acquisition part and the pore pressure data acquisition part are used for data acquisition. The collected data can be stored and analyzed in a data collection unit (e.g., a computer).

In the coal underground gasification pollution evaluation method, preferably, a combustible screen and/or a casing is/are arranged in a coal seam prefabricated well hole to support the well hole.

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

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

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

In the method for evaluating underground coal gasification pollution, 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 overburden pressure and horizontal main stress.

In one embodiment, the confining pressure applying process comprises: the used injection medium of exerting the confined pressure carries out one-level pressure boost through the confined pressure booster pump, inputs the confined pressure numerical value that will exert through pressure controller, and pressure controller control servo booster carries out the second grade pressure boost to the used injection medium of exerting the confined pressure after the one-level pressure boost, thereby the confined pressure is exerted to the experimental cavity section of thick bamboo and is exerted the confined pressure thereby realizing exerting the confined pressure to the coal seam under the used injection medium's of exerting the confined pressure effect of part after the second grade pressure boost to the confined pressure in the experimental cavity. More preferably, when 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 to be constant at the set value.

In the method for evaluating underground coal gasification pollution, preferably, the applying pore pressure comprises applying pore pressure with different pressure values to the coal bed in the longitudinal direction to realize the change of simulated pore pressure along with depth.

In one embodiment, the pore pressure applying process comprises: the injection medium for applying pore pressure is subjected to primary pressurization through the pore pressure booster pump, a pore pressure numerical 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 for applying pore pressure after primary pressurization, and the pore pressure injection hole in the experimental cavity applies pore pressure under the action of the injection medium for applying pore pressure after secondary pressurization. More preferably, the pore pressure is maintained at the set value after the pore pressure data collected by the pore pressure data monitoring part reaches the pore pressure value set by the pressure controller.

In the coal underground gasification pollution evaluation method, preferably, after confining pressure and pore pressure are applied, pressure testing is performed before the step 3), if the pressure testing is qualified, the step 3) is performed, and if the pressure testing is not qualified, the step 1) is performed again after the coal underground gasification pollution evaluation system is overhauled; wherein, the confining pressure and the pore pressure are applied for 36h, the variation range of the confining pressure is within +/-5 percent, the variation range of the pore pressure is within +/-5 percent, and the pressure test is qualified. The pressure test is qualified, and the coal underground gasification pollution evaluation system has good tightness and the condition for subsequent operation.

In the method for evaluating underground coal gasification pollution, it is preferable that at least one of the confining pressure data, the 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 is collected. In a specific embodiment, the confining pressure data monitoring piece transmits the collected confining pressure data to the pressure controller, the pore pressure data monitoring piece transmits the collected pore pressure data to the pressure controller, the servo supercharger feeds back the confining pressure, the flow rate, 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 quantity data, the flow rate 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 gasification agent injection pressure is lower than the applied pore pressure. The real coal bed contains coal bed water, the domestic coal bed is generally in a state of under-compaction, namely the pore pressure gradient of the coal bed is generally less than 1MPa/100m, and for safety and environmental protection, the injection pressure of a gasifying agent is less than the pore pressure of the coal bed in the field test of underground coal gasification 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 coal underground gasification pollution evaluation method, the injection pressure of the gasification agent is less than the applied pore pressure, so that the real site situation is better simulated.

In the method for evaluating pollution of underground coal gasification, preferably, the performing of simulated gasification of a coal seam includes: the method comprises the following steps that an ignition unit is used for igniting a coal seam at a first ignition position under the condition that a combustion improver is injected into the coal seam, a gasifying agent is injected into the coal seam after the coal seam is ignited for coal seam gasification, when the heat value of synthetic gas generated by coal seam gasification is reduced to 65% -75% of the initial heat value, the ignition of the coal seam and the injection of the gasifying agent into the coal seam after the coal seam is ignited are repeated at the next ignition position for coal seam gasification, and the operation of injecting the gasifying agent into the coal seam for coal seam gasification is completed until the final ignition position completes the ignition of the coal seam and the ignition of the coal seam, so that the whole coal seam simulated gasification process is completed; synthetic gas generated in the coal bed simulation gasification process enters a synthetic gas treatment unit for treatment and then is discharged; and the synthetic gas generated in the coal bed simulated gasification process enters a synthetic gas treatment unit for treatment and then is discharged. More preferably, the ignition positions are arranged in order from a position far from the position where the gasification agent is injected to a position near the position where the gasification agent is injected (the first ignition position is farthest from the position where the gasification agent is injected compared with the other ignition positions, and the subsequent ignition positions are successively closer to the position where the gasification agent is injected). In order to improve the coal gasification amount of a single gasification cavity and simultaneously control the reduction amplitude of the heat value of the synthetic gas in the process of changing the ignition position and avoid large fluctuation of the heat value of the synthetic gas, when the heat value of the synthetic gas is reduced to be within 65-75% of the initial heat value, the next ignition position repeats the processes of coal bed ignition and coal bed gasification by injecting a gasification agent into the coal bed after the coal bed ignition so as to start a gasification experiment at a new position. The ignition position is sequentially arranged from the position far away from the gasification agent injection position to the position close to the gasification agent injection position, so that the simulation of the controlled injection point continuous retreating process is realized.

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

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

In the underground gasification test method, the injection speed of the combustion improver and the gasifying agent can be determined in a conventional manner, for example, based on multiple factors of gasifying agent pressure, coal quality, fire retardant type and simulated borehole diameter.

In one embodiment, the process of igniting the coal seam and injecting the gasifying agent into the ignited coal seam in the step 3) comprises the following steps: heating wires in a borehole are heated through the ignition controller, oxygen is injected continuously in a small discharge amount to serve as a combustion improver, a gasifying agent is injected after the ignition of the coal bed is confirmed, and the injection flow and the injection mode of the gasifying agent are controlled to gasify the coal bed.

In the method for evaluating pollution of underground coal gasification, the gasifying agent preferably includes: at least one of an air gasifying agent, an oxygen-enriched air gasifying agent and an oxygen-enriched air and steam gasifying agent. More preferably, when the gasification agent is oxygen-enriched air and steam gasification agent, the gasification agent is injected in two stages or in one stage; wherein the two-stage implant comprises: oxygen-enriched air is injected into the first section, the volume concentration of oxygen in the oxygen-enriched air is 21-50%, and the oxygen-enriched air flow rate is preferably 0-30m³H; the stage is mainly the coal oxidation combustion exothermic reaction; the second stage is filled with steam at a flow rate of 0-30m³The stage is mainly subjected to water gas reaction and methanation reaction; the two stages are sequentially and repeatedly carried out; the one-stage injection is to inject oxygen-enriched air and water vapor into the coal bed simultaneously, wherein the volume concentration of oxygen in the oxygen-enriched air is 21-50%, the mass ratio of water vapor to oxygen in the gasification agent is 2:1-4:1, and the flow rate of the gasification agent is preferably 0-30m³/h。

In the method for evaluating underground coal gasification pollution, the flow rate of the gasification agent is preferably 0-30m³/h。

In one embodiment, air is used as the gasifying agent, and the flow rate of the gasifying agent is controlled to be 0-30m³And h, when the calorific value of the synthetic gas generated by coal bed gasification is reduced to 65-75% of the initial calorific value, dragging the electric heating wire to the next ignition position, and repeating the processes of coal bed ignition and gasification agent injection to the ignited coal bed.

In one 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 0-30m³When 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 are repeated to inject a gasification agent into the coal bed to gasify the coal bedAnd (6) carrying out the process.

In a specific embodiment, oxygen-enriched air and water vapor are used as gasifying agents, and the gasifying agents are injected in a two-stage mode; oxygen-enriched air is injected into the first section, the volume concentration of oxygen in the oxygen-enriched air is 21-50%, and the flow rate of the oxygen-enriched air is 0-30m³The stage is mainly the coal oxidation combustion exothermic reaction; the second stage is filled with steam at a flow rate of 0-30m³The stage is mainly subjected to water gas reaction and methanation reaction; the two stages are sequentially and repeatedly carried out; when the calorific value of the synthesis gas generated by coal bed gasification is reduced to 65% -75% of the initial calorific value, the electric heating wire is dragged to the next ignition position, and the process of injecting a gasification agent into the coal bed to gasify the coal bed is repeated after the ignition of the coal bed and the ignition of the coal bed.

In a specific embodiment, oxygen-enriched air and water vapor are used as gasifying agents, and the gasifying agents are injected in a single-stage mode; oxygen-enriched air and water vapor are simultaneously injected into the coal bed, 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 preferably 0-30m³And h, when the calorific value of the synthetic gas generated by coal bed gasification is reduced to 65-75% of the initial calorific value, dragging the electric heating wire to the next ignition position, and repeating the processes of coal bed ignition and then injecting a gasification agent into the coal bed to gasify the coal bed.

In a specific embodiment, the heating value of the syngas is determined by analyzing and metering the composition of the syngas using a gas detection device, such as a gas chromatograph, in the syngas processing unit.

In the method for evaluating pollution of underground coal gasification, the injection flow rate, pressure and temperature data of the gasification agent are preferably collected in step 3).

In one embodiment, the step of processing the synthesis gas generated in the coal bed simulation gasification process into a synthesis gas processing unit comprises: the generated synthesis gas is subjected to dust removal, coke removal and sulfur removal to remove solid dust, tar and sulfur-containing toxic gas in the synthesis gas respectively, then the synthesis gas enters a combustion chamber to be subjected to synthesis gas combustion treatment, and the gas after the combustion treatment is discharged; wherein, the synthesis gas treated by the dust remover, the decoking device and the desulfurizing device is subjected to component analysis and measurement once by using a gas chromatograph at intervals of 1-5 minutes.

In the method for evaluating underground coal gasification pollution, preferably, before the detection of the sewage in the gasification cavity, the gasification cavity is subjected to gas purging; on one hand, residual synthesis gas in the inner cylinder of the gasification cavity of the pollution evaluation device is discharged, and on the other hand, the temperature of the pollution evaluation device is cooled.

In the method for evaluating underground coal gasification pollution, preferably, during the detection of sewage in the gasification cavity, coal bed water is injected into the experimental cavity by water injection.

In the method for evaluating underground coal gasification pollution, preferably, in the process of detecting the sewage in the gasification cavity, after the sewage in the gasification cavity is displaced by injecting water into the experimental cavity, the displaced sewage is subjected to solid large particle sedimentation treatment, and then the water quality detection is performed on the sewage.

In the method for evaluating underground coal gasification pollution, preferably, the detection of the sewage in the gasification cavity further comprises purifying the displaced sewage, and detecting the water quality of the sewage in the purification process and after the purification process.

In a specific embodiment, coal bed water is injected into a well hole of a gasification cavity through a high-pressure water pump to replace sewage in the gasification cavity, the pump injection pressure is smaller than the pore pressure of a coal bed, the sewage firstly passes through a settling tank to settle large-size solid residues and coal dust, and water quality detection equipment analyzes the water quality of the sewage in the settling tank to master the types and the contents of organic and inorganic pollutants; the sewage that flows through the settling tank successively gets into tertiary ground water purification installation, and purifier purifies treatment to sewage in grades, and the sewage after the processing all detects through water quality testing equipment, and all detected data all record is in water quality testing equipment. The sewage after purification treatment has two treatment methods, one is to open a sewage recovery tank for centralized treatment; one is to pump the mixture into the gasification well hole again through a high-pressure water pump and simulate the pumping-out of the ground treatment process, and the step can also simulate the pollution treatment processes such as a chemical oxidation technology, a biodegradation technology and the like.

In the method for evaluating underground coal gasification pollution, preferably, after the detection of the sewage in the gasification cavity is finished, confining pressure and pore pressure unloading are performed. Specifically, the method comprises the following steps: closing the confining pressure booster pump and the pore pressure booster pump, enabling the confining pressure and the pore pressure to return to zero through the pressure controller, and slowly reducing the pump pressure of a confining pressure pressurizing component (such as a hydraulic rod) in the experimental cavity and slowly releasing the acting force until the confining pressure value acquired by the confining pressure data monitoring part is zero, so that the confining pressure is completely unloaded; opening the pore pressure relief hole on the experiment chamber until the pore pressure value collected by the pore pressure collecting piece is zero, indicating that the pore pressure is completely unloaded; and after the confining pressure and the pore pressure are unloaded and cooled for 12 hours, the pollution evaluation device is dissected.

The real coal bed contains coal bed water, the domestic coal bed is generally in a state of being under-compacted, namely the pore pressure of the coal bed is generally less than 1MPa/100m, for safety and environmental protection, the injection pressure of a gasifying agent is less than the pore pressure of the coal bed in the coal underground gasification field test so as to reduce outward migration of synthetic gas in the gasification process, the injection pressure of the gasifying agent in the coal underground gasification process is directly limited by the pore pressure of the coal bed, the gasification pressure of a shallow coal bed with the pressure of 1500m is inevitably less than 15MPa, and in order to scientifically guide pollution evaluation of coal underground gasification, a 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 conditions of coal, can simulate the confining pressure and pore pressure of a deep coal bed (for example, a coal bed below 1500 meters), solves the difficult problems of coal bed confining pressure and pore pressure loading, and fills the technical blank of the test. In a preferred scheme, simulation of different coal seam production states and gasification well types (such as a U-shaped horizontal well and a double-horizontal well) can be achieved.

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

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

Drawings

Fig. 1 is a front view of the contamination evaluation apparatus provided in example 1.

Fig. 2 is a left side view of the contamination evaluation apparatus provided in example 1.

Fig. 3 is a plan view of the contamination evaluation apparatus provided in example 1.

Fig. 4 is a schematic view of the hole pressure injection hole on the inner wall (side) of the test chamber of the contamination evaluation apparatus provided in example 1.

Fig. 5 is a partially enlarged view of a hole-pressure injection hole provided in example 1.

Fig. 6 is a partially enlarged view of the hydraulic lever provided in embodiment 1.

FIG. 7 is an enlarged view of the inner cylinder of the gasification chamber 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 view showing the arrangement of a thermocouple of the contamination evaluation apparatus provided in example 2.

Fig. 11 is a schematic view showing the arrangement of a pressure change sensor of the contamination evaluation device provided in example 2.

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

Fig. 13 is a schematic view showing the arrangement of gas detection sensors of the contamination evaluation device provided in example 2.

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

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

The main reference numbers:

1 oxygen cylinder, 2 nitrogen cylinder, 3 steam generator, 4 air compressor, 5 flow pressure meter, 6 thermocouple thermometer, 7 gasifying agent pipeline branch valve, 8 gasifying agent pipeline main 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 gasification cavity outer barrel, 15 hydraulic rod, 16 gasification 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 top plate, 27 coal bed, 28 borehole, 29 bottom plate, 30 gasification cavity, 31 pollution evaluation device left end cover, 32 gasification cavity left end cover sealing bolt, 33 gasification cavity left end cover, 34 pore pressure relief holes, 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 purification pipeline control valve, 45 cooler, 46 dust remover, 47 decoking device, 48 sulfur remover, 49 gas detection equipment, 50 combustion chamber, 51 sewage detection unit control valve, 52 settling tank, 53 first stage groundwater purification device, 54 second stage groundwater purification device, 55 third stage groundwater purification device, 56 water quality detection equipment, 57 sewage tank control valve, 58 sewage recovery tank, 59 high pressure water pump, 60 underground water tank control valve, 61 underground water tank, 62 high pressure water valve, 63 pressure sensor, 64 pore pressure injection hole, 65 one-way valve, 66 thermocouple, 67 stress strain sensor, 68 pore pressure sensor, 69 gas detection sensors, 70 hydraulic rod slide rails, 71-hole pressure wiring grooves, 72 hydraulic rod fixing bases, 73 hydraulic telescopic rods and 74 hydraulic rod sliding heads.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.

Example 1

The present embodiment provides a pollution evaluation device which can be applied to underground coal gasification pollution evaluation, and the structure of the pollution evaluation device is shown in fig. 1-9, specifically comprises a pollution evaluation device body (i.e. a test chamber),

the pollution evaluation device body is provided with a gasification cavity 30 (namely an experimental cavity), a pollution evaluation device shell (namely an experimental cabin shell) and arefractory brick 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 housing of the pollution evaluation device is made of a high-pressure-resistant steel plate with the thickness of 1cm, can bear the high pressure of 35MPa, and is cuboid, and the specific size, height, width and length are respectively 2m multiplied by 4 m; 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, wherein 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 the barrel wall of the pollution evaluation device outer barrel and a pollution evaluation device right end cover 35 together through 8 pollution evaluation device right end cover sealing bolts 23; the upper wall, the front wall and the rear wall of the outer barrel 12 of the pollution evaluation device are respectively provided with 4 reserved detection pipe columns 17 (namely data acquisition wiring channels) which 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 wiring channel 24, a pore pressure wiring channel 24 and a pore pressure relief hole 34;

the gasification cavity 30 is a cuboid and comprises a gasification cavity left end cover 33 (namely an experimental cavity cover) and a gasification cavity barrel body (namely an experimental 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 (namely an experimental cavity outer barrel) and a gasification cavity inner barrel 16 (namely an experimental cavity inner barrel), and the gasification cavity outer barrel 14 and the barrel bottom are integrally formed; the inner cylinder 16 of the gasification cavity is formed by enclosing 4 flat plates with the size of 2.2m × 1.5m, and the 4 flat plates enclose a cuboid or a cube with two open ends, for each flat plate, only one end of the flat plate abuts against the plate surface of one flat plate adjacent to the flat plate, the plate surface of the flat plate is used as an abutting plate surface of the other flat plate adjacent to the flat plate, and each flat plate can slide along the abutting plate surface (as shown in fig. 7-9); the space thus formed by the flat plates can be reduced or enlarged in the horizontal and vertical directions; the gasification cavity outer cylinder 14 is made of temperature and pressure resistant steel and can bear 35MPa high pressure and 1300 ℃ high temperature; 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, and the confining pressure applying component is connected with a confining pressure pipeline (the confining pressure pipeline comprises 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 connected in sequence, and the outer wall of the gasification cavity inner cylinder 14 is provided with a hydraulic rod sliding rail 70; a hydraulic rod fixing base 72 of the hydraulic rod 15 is fixed on the inner wall of the air cylinder 14, a 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; an injection medium for applying confining pressure enters the hydraulic rod 15 through the confining pressure pipeline to realize that the hydraulic rod 15 applies confining pressure on the inner cylinder 16 of the gasification cavity, so that the confining pressure is applied to a sample to be detected loaded in the inner cylinder 16 of the gasification cavity; the upper wall of the gasification cavity inner cylinder 16 and the upper wall of the gasification cavity outer cylinder 14 are provided with 7 × 11 hydraulic rods 15 (7 rows × 11 columns) connected with a first confining pressure pipeline at equal intervals, the lower wall of the gasification cavity inner cylinder 16 and the lower wall of the gasification cavity outer cylinder 14 are provided with 7 × 11 hydraulic rods 15 (7 rows × 11 columns) connected with a second confining pressure pipeline at equal intervals, the front wall of the gasification cavity inner cylinder 16 and the front wall of the gasification cavity outer cylinder 14 are provided with 6 × 11 hydraulic rods 15 (6 rows × 11 columns) connected with a third confining pressure pipeline at equal intervals, and the rear wall of the gasification cavity inner cylinder 16 and the rear wall of the gasification cavity outer cylinder 14 are provided with 6 × 11 hydraulic rods 15 (6 rows × 11 columns) connected with a third confining pressure pipeline at equal intervals;

the front wall and the rear wall of the gasification cavity inner barrel 16 are both provided with hole pressure wiring grooves 71, and hole pressure pipelines are laid in the hole pressure wiring grooves 71; the front wall and the rear wall of the inner cylinder 16 of the gasification cavity 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), the hole pressure pipelines are provided with one-way valves 65 (the one-way valves 65 are arranged to avoid backflow of hole pressure injection media), and the injection media for applying hole pressure apply hole pressure to the sample to be detected loaded in the inner cylinder 16 of the gasification cavity through the hole pressure pipelines into the hole pressure injection holes 64; the hole pressure injection holes 64 are arranged in the wall of the gasification chamber inner cylinder 16, the hole pressure injection holes 64 are arranged on the front wall of the gasification chamber inner cylinder 16 at equal intervals, the hole pressure injection holes 64 are arranged on the rear wall of the gasification chamber inner cylinder 16 at equal intervals, the hole pressure injection holes 64 are arranged on the front wall of the gasification chamber inner cylinder 10 × 24 (10 rows × 24 rows), the hole pressure injection holes 64 on the front wall and the rear wall of the gasification cavity inner cylinder 16 are sequentially 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 64 from top to bottom, the hole pressure injection holes 64 on the front wall and the rear wall of the gasification cavity inner cylinder 16 are respectively connected with a first hole pressure pipeline to a tenth hole pressure pipeline in sequence by taking rows as units, specifically, the first row of hole pressure injection holes 64 are connected with a first hole pressure pipeline, the second row of hole pressure injection holes 64 are connected with a second hole pressure pipeline … …, and the tenth row of hole pressure injection holes 64 are connected with a tenth hole pressure pipeline;

thegasification cavity 30 is further provided with a confining pressure data monitoring part and a pore pressure data monitoring part, wherein the confining pressure data monitoring part is used for acquiring confining pressure data of the gasification cavityinner cylinder 16, and a stress sensor is selected and arranged on the cylinder wall of the gasification cavityinner cylinder 16; the pore pressure data monitoring piece is used for acquiring pressure data of a porepressure injection hole 64, apressure sensor 63 is selected, and thepressure sensor 63 is connected with the porepressure injection hole 64;

the gasification cavity 30 is further provided with a data acquisition assembly, wherein the data acquisition assembly comprises a gas data acquisition part, a temperature data acquisition part, a stress strain data acquisition part and a pore pressure data acquisition part; wherein the gas data acquisition part is used forCollecting CO and CO in the inner cylinder 16 of the gasification cavity₂、CH₄、H₂The gas data acquisition part comprises a gas detection sensor 69 and a gas detection collector 21, the gas detection sensor 69 is arranged inside the gasification cavity inner cylinder 16, the gas detection collector 21 is arranged outside the pollution evaluation device body, and the gas detection sensor 69 is connected with the gas detection collector 21 through a reserved detection pipe column 17 in a line manner; 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, the temperature data acquisition part comprises a thermocouple 66 and a temperature collector 18, the thermocouple 66 is arranged in the gasification cavity inner cylinder 16, the temperature collector 18 is arranged outside the pollution evaluation device body, and the thermocouple 66 is in line connection with the temperature collector 18 through a reserved detection pipe column 17; 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, the stress-strain data acquisition part comprises a stress-strain sensor 67 and a stress-strain data acquisition unit 19, the stress-strain sensor 67 is arranged inside the gasification cavity inner cylinder 16, the stress-strain data acquisition unit 19 is arranged outside the pollution evaluation device body, the stress-strain sensor 67 and the stress-strain data acquisition unit 19 are in circuit connection through a reserved detection pipe column 17, and the stress-strain sensor 67 and the stress-strain data acquisition unit 19 are in circuit connection through the reserved detection pipe column 17; the pore pressure data acquisition part is used for acquiring the pore pressure of a sample to be detected loaded in the gasification cavity inner cylinder 16, the pore pressure data acquisition part comprises a pore pressure sensor 68 and a pore pressure collector 20, the pore pressure sensor 68 is arranged in the gasification cavity inner cylinder 16, the pore pressure collector 20 is arranged outside the pollution evaluation device body, and the pore pressure sensor 68 is in line connection with the pore pressure collector 20 through a reserved detection pipe column 17;

the pollution evaluation device body is provided with a gasifying agent injection channel 10 (namely an experimental injection fluid channel) and a synthetic gas production channel 25 (namely an experimental production fluid channel); the experiment injection fluid channel and the experiment output fluid channel are both communicated with the gasification cavityinner barrel 16; the gasificationagent injection channel 10 is arranged on theleft end cover 33 of the gasification cavity and penetrates through theleft end cover 31 of the pollution evaluation device to be communicated with the outside, and the syntheticgas output channel 25 is arranged on the barrel bottom of the barrel body of the gasification cavity and penetrates through the barrel bottom of theouter barrel 12 of the pollution evaluation device (namely, theright end cover 35 of the pollution evaluation device) to be communicated with the outside;

example 2

The present embodiment provides an underground coal gasification pollution evaluation system applicable to underground coal gasification pollution evaluation, which, as shown in fig. 10 to 14, specifically includes the pollution evaluation device provided in embodiment 1, a gasification agent preparation unit, a confining pressure and pore pressure loading unit, a synthesis gas treatment unit, a data acquisition unit, a sewage detection unit, and an ignition unit; the gasification agent preparation unit is connected with a gasification agent injection channel 10 of the pollution evaluation device and is used for injecting gasification agents into 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 through a confining pressure and pore pressure wiring channel 24 of the pollution evaluation device 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 quality of the sewage produced in the pollution evaluation device; the data acquisition unit is connected with a gas detection collector 21, a temperature collector 18, a stress strain data collector 19 and a pore pressure collector 20 of a data acquisition part in the pollution evaluation device, and stores the volume and concentration of the escaped gas, the oxygen concentration, the temperature, the stress strain and the pore pressure data in the test process in real time for subsequent analysis;

the gasification agent preparation unit can realize the preparation of three types of gasification agents, 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 respectively comprise a flow pressure gauge 5, a thermocouple thermometer 6 and a gasifying agent pipeline branch valve 7 with controllable opening degree which are sequentially connected; the oxygen cylinder 1 is connected with the oxygen flow control assembly to form an oxygen supply branch, the nitrogen cylinder 2 is connected with the nitrogen flow control assembly to form a nitrogen supply branch, the steam generator 3 is connected with the steam flow control assembly to form a steam supply branch, and the air compressor 4 is connected with the air flow control assembly 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 are connected with a gasification agent injection channel 10 of the pollution evaluation device, so that a gasification agent preparation unit is connected with the gasification agent injection channel 10 of the pollution evaluation device, and a gasification agent pipeline main valve 8 is arranged on a connecting pipeline;

the sample to be detected loaded in the gasification cavity inner cylinder 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 well hole 28 is prefabricated in the coal seam 27, and the well hole 28 is respectively communicated with the gasification agent injection channel 10 and the synthetic gas production channel 25; a combustible screen or casing is provided in the wellbore 28 to support 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 experiment process, 4 groups of thermocouples 66 are arranged in the sample to be tested at equal intervals along the extending direction of the borehole 28, each group of thermocouples 66 is arranged on a cross section of the sample to be tested, which is perpendicular to the extending direction of the borehole 28, and each group of thermocouples 66 is provided with 20 rows of 3 thermocouples 66, specifically, as shown in fig. 10, 3 rows of thermocouples 66 are arranged on the arrangement cross section of each group of thermocouples 66 along the longitudinal direction from the top plate 26 to the bottom plate 29, and the row spacing between adjacent thermocouples 66 closer to the borehole 28 is smaller, and the spacing between adjacent thermocouples 66 closer to the borehole 28 in each group of thermocouples 66 is smaller; the stress-strain sensors 67 are arranged on the top of the coal seam 27 and the top plate 26 to collect stress-strain data of the top plate 26, 4 groups of stress-strain sensors 67 are arranged in the sample to be detected at equal intervals along the extension direction of the borehole 28, each group of stress-strain sensors 67 is arranged on a section of the sample to be detected, which is perpendicular to the extension direction of the borehole 28, and each group of stress-strain sensors 67 is provided with 14 rows of stress-strain sensors 67, and the specific arrangement is as shown in fig. 11, wherein the closer the arrangement section of each group of stress-strain sensors 67 is to the borehole 28, the smaller the distance between adjacent stress-strain sensors 68 is; the pore pressure sensors 68 are arranged on the coal seam 27 to collect 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 borehole 28, each group of pore pressure sensors 68 is arranged on a section of the sample to be measured, which is perpendicular to the extending direction of the borehole 28, and each group of pore pressure sensors 68 is provided with 2 groups of pore pressure sensors 68 on the front side and the rear side of the borehole 28, and the arrangement is shown in fig. 12; the gas detection sensors 69 are arranged on the coal seam 27 and the top plate 26 to collect the volume and concentration of the escaped gas and the concentration of oxygen, 4 groups of gas detection sensors 69 are arranged at equal intervals along the extension direction of the borehole 28, each group of gas detection sensors 69 is arranged on a section, perpendicular to the extension direction of the borehole 28, of the sample to be detected, and each group of gas detection sensors 69 is provided with 3 pore pressure sensors 68 on the front side and the rear side of the borehole 28 and on the upper part of the borehole from large to small according to the distance from the borehole, specifically, as shown in fig. 13, 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 are positioned in the coal seam 27; the setting section of each group of thermocouples 66 and the setting section of each group of stress-strain sensors 67, the setting section of each group of pore pressure sensors 68 and the setting section of each group of gas detection sensors 69 are the same section;

the data acquisition unit comprises a computer, the computer is connected with a data acquisitionpart temperature collector 18, a stressstrain data collector 19, agas detection collector 21 and apore pressure collector 20 in the pollution evaluation device, and the volume and concentration of dissipated gas, the concentration of oxygen, the temperature, the stress strain and the pore pressure data in the test process are stored 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 confining pressure application and injection medium water for pore pressure application; the confining pressure liquid source tank 37 is connected with a confining pressure booster pump 38 to form a confining pressure primary pressurizing branch, the hole pressure liquid source tank 36 is connected with a hole pressure booster pump 39 to form a hole pressure primary pressurizing branch, the confining pressure primary pressurizing branch is connected with a servo booster 41 after being connected in parallel with the hole pressure primary pressurizing branch, a pressure control valve 40 is arranged on a connecting pipeline, 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 supercharger 41 to control the pressure application of the servo supercharger 41, and a confining pressure data monitoring piece and a pore pressure data monitoring piece of the pollution evaluation device are respectively connected with the pressure controller 42 to transmit data acquired by the confining pressure data monitoring piece and the pore pressure data monitoring piece to the pressure controller 42; the computer 43 is connected with the pressure controller 42 and is used for monitoring, acquiring and analyzing the confining pressure and pore pressure loading and unloading processes in real time; when the 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 is subjected to secondary pressurization through the servo booster 41, and then flows into a confining pressure applying part of the pollution evaluation device through a 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; when the pore pressure pressurization is carried out, the injection medium provided by the pore pressure liquid source tank 36 is subjected to primary pressurization through the pore pressure booster pump 39, then is subjected to secondary pressurization through the servo booster 41, and then flows into the pore pressure injection hole of the pollution evaluation device through the pore pressure injection pipeline to provide pressure for the pore pressure injection hole 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 and reaches a set value. The servo booster is connected with the confining pressure pipeline and the pore pressure pipeline through a high-pressure sealing pipeline;

the ignition unit comprises an ignition controller 9 and an electric heating wire, the ignition controller 9 is arranged on a pipeline connecting the gasification agent preparation unit and the pollution evaluation device, the ignition controller 9 is used as an ignition switch and is used for controlling initial ignition and continuous retreating ignition operation in the test process, and the electric heating wire is arranged in aborehole 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 theborehole 28, and the other end of the electric heating wire is arranged outside the pollution evaluation device) and is used for providing the temperature required by coal combustion in the test process, and the ignition operation is realized by matching with a combustion improver; different ignition positions can be simulated by dragging the heating wire, so that a controlled injection point continuous retreating process is simulated;

the synthetic gas treatment unit comprises a cooler 45, a dust remover 46, a decoking device 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 synthetic gas production channel 25 of the pollution evaluation device, so that the synthetic gas treatment unit is connected with the synthetic gas production channel 25 of the pollution evaluation device, and a purification 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 production 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 production channel 25 of the pollution evaluation device, the decoking device 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 measurement on the synthesis gas treated by the dust remover 46, the decoking device 47 and the sulfur remover 48; wherein the gas detection device 49 is a gas chromatography-mass spectrometry (GCMS);

the sewage detection unit comprises an underground water tank 61, a water injection device, a sewage purification device, a sedimentation tank 52, a water quality detection device 56 and a sewage recovery tank 58; the water injection equipment adopts a high-pressure water pump 59, the underground water tank 61 is connected with the pump inlet of the high-pressure water pump 59, an underground water tank control valve 60 is arranged on a connecting pipeline, the pump outlet of the high-pressure water pump 59 is connected with the gasification 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 groundwater primary purification device 53, a groundwater secondary purification device 54 and a groundwater tertiary purification device 55, the sedimentation tank 52, the groundwater primary purification device 53, the groundwater secondary purification device 54 and the groundwater tertiary purification device 55 are sequentially connected, a water inlet of the sedimentation tank 52 is connected with the synthesis gas generation 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 groundwater primary purification device 53, the groundwater secondary purification device 54 and the groundwater tertiary purification device 55 and is used for performing water quality detection on sewage precipitated by the sedimentation tank 52, sewage purified by the groundwater primary purification device 54, sewage purified by the groundwater secondary purification device 55 and sewage purified by the groundwater tertiary purification device 56; a water outlet of the groundwater tertiary purification device 55 is respectively connected with a water inlet of a sewage recovery tank 58 and a pump inlet of a high-pressure water pump 59, and a sewage pipe control valve 57 is arranged on a connecting pipeline between the water outlet of the groundwater tertiary purification device 55 and the sewage recovery tank 58; the water quality detection equipment 56 comprises an organic pollutant detection device and an inorganic pollutant detection device, wherein the organic pollutant detection device is a gas chromatography-mass spectrometry (GC-MS) combined instrument, and the inorganic pollutant detection device is a plasma emission mass spectrometry (ICP-MS) combined instrument; in the coal underground gasification pollution evaluation system, all pressure-bearing connecting pipelines use high-pressure-resistant pipelines which can bear at least 35MPa of pressure and can realize good sealing, and valves on all pipelines can effectively control the communication of the pipelines and can realize good sealing.

Example 3

The embodiment provides a method for evaluating pollution caused by underground coal gasification, which is implemented by using the system for evaluating pollution caused by underground coal gasification provided inembodiment 2, and the method is shown in fig. 15, and comprises the following steps:

1) preparing aroof 26, afloor 29, and acoal seam 27 for gasification test: carrying out rock mechanical tests according to coring data of a top plate and a bottom plate of a coal seam of an area to be simulated, measuring mechanical properties (elastic modulus, Poisson ratio, tensile strength and compressive strength), and preparing atop plate 26 and abottom plate 29 for gasification experiments according to a material similarity principle; the thickness of thetop plate 26 is 0.25m, the length is 2.2m, the width is 1.5m, the thickness of thecoal seam 27 is 1m, the length is 2.2m, the width is 1.5m, the thickness of thebottom plate 29 is 0.25m, the length is 2.2m, the width is 1.5m, the coal blocks obtained from the coal seam of the simulation area are cut into regular cubic coal blocks of 0.4m × 0.4m × 0.4m, and the regular cubic coal blocks are used for preparing thecoal seam 27 for gasification experiments;

prefabricatingwellbore 28 and positioning heating wires inprefabricated wellbore 28 according to the initial ignition position: prefabricating a borehole 28 required by a simulation U-shaped horizontal well gasification process in acoal seam 27, specifically prefabricating a single-hole borehole 28 in thecoal seam 27, wherein the diameter of the artificially prefabricatedborehole 28 is 10cm, a combustible sleeve is arranged to support theborehole 28, and the initial position of an electric heating wire is arranged at a position which is about 0.5m away from the bottom of a gasification cavity barrel body, namely a position which is 0.5m away from the right end face of the gasification cavityinner barrel 16 after the coal seam is filled into the gasification cavityinner barrel 16; the gasificationagent injection channel 10 and the synthesisgas production channel 25 are respectively arranged at the left end and the right end of the pollution evaluation device body;

roof 26,floor 29 andcoal seam 27 are pre-installed withgas detection sensors 69, thermocouples 66,stress strain sensors 67 and pore pressure sensors 68: prefabricating mounting holes for a gas data acquisition member, a temperature data acquisition member, a stress strain data acquisition member and a pore pressure data acquisition member in theroof 26, thefloor 29 and thecoal seam 27, and mounting agas detection sensor 69, a thermocouple 66, astress strain sensor 67 and apore pressure sensor 68 in theroof 26, thefloor 29 and thecoal seam 27; the arrangement of thegas detection sensor 69, the thermocouple 66, the stress-strain sensor 67, and thepore pressure sensor 68 in theroof 26, thefloor 29, and thecoal seam 27 is the same as that of thegas detection sensor 69, the thermocouple 66, the stress-strain sensor 67, and thepore pressure sensor 68 in example 2 (see, for example, fig. 10 to 13);

roof 26,floor 29 andcoal seam 27 fill: filling thebottom plate 29, thecoal seam 27 and thetop plate 26 into the gasification cavityinner barrel 16 in the sequence of thebottom plate 29, thecoal seam 27 and thetop plate 26 from bottom to top in the gasification cavityinner barrel 16; coal blocks of thecoal bed 27 for the gasification experiment are coated with coal powder and clay, so that the integrity of the coal bed is ensured; thecoal seam 27 is smeared with coal powder and clay at the joints of thetop plate 26 and thebottom plate 29, so that the sealing performance and 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 cavityinner barrel 16;

then, assembling a pollution evaluation device, and connecting the whole coal underground gasification pollution evaluation system; debugging the connected coal underground gasification pollution evaluation system (determining that the line connection is correct, all parts have normal functions and good switching performance), and performing thesubsequent step 2 after debugging is not problematic);

2) carrying out confining pressure and pore pressure application according to confining pressure and pore pressure values of the coal seam of the simulation area:

in the embodiment, the simulated coal seam depth is 1000m, the vertical stress borne by the coal seam is 25.4MPa, the maximum horizontal main stress is 18MPa, the minimum horizontal main stress is 16.7MPa, a borehole is arranged along the minimum horizontal main stress, and the coal seam pore pressure is 8.7MPa according to coal seam gas well data, coal seam drilling data, well testing data, array acoustic logging data and the like.

Respectively control the hydraulic stem 15 of being connected with first confined pressure pipeline, the hydraulic stem 15 of being connected with second confined pressure pipeline, carry out confined pressure with the hydraulic stem 15 of being connected with third confined pressure pipeline and exert, specifically: the injection medium for applying confining pressure is subjected to primary pressurization through a confining pressure booster pump 38, a confining pressure numerical value to be applied is input through a pressure controller 42 (wherein a vertical acting force is 25.4MPa of the confining pressure numerical value applied by a hydraulic rod 15 connected with a first confining pressure pipeline, the confining pressure numerical value applied by the hydraulic rod 15 connected with the first confining pressure pipeline is 25.4MPa, a horizontal main stress is 18MPa of the confining pressure numerical value of the hydraulic rod 15 connected with a third confining pressure pipeline), the pressure controller 42 controls a servo supercharger 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 is slowly displaced under the action of the injection medium for applying confining pressure after secondary pressurization so as to apply a vertical acting force and a horizontal acting force on the gasification cavity inner cylinder 16 for simulating the formation pressure of a coal seam and the maximum horizontal main stress; when the confining pressure data acquired by the confining pressure data monitoring part reaches the confining pressure value set by the pressure controller 42, the confining pressure is maintained to be unchanged at the set value; the pore pressure applying is carried out by respectively controlling the pore pressure injection hole 64 connected with the first pore pressure pipeline, the pore pressure injection hole 64 … … connected with the second pore pressure pipeline and the pore pressure injection hole 64 connected with the tenth pore pressure pipeline, specifically: the injection medium for applying the pore pressure is subjected to primary pressurization by the pore pressure booster pump 39, and the confining pressure value to be applied is input by the pressure controller 42 (where the pore pressure value applied to the pore pressure injection hole 64 connected to the first pore pressure line is 8.67MPa, the pore pressure value applied to the pore pressure injection hole 64 connected to the second pore pressure line is 8.68MPa, the pore pressure value applied to the pore pressure injection hole 64 connected to the third pore pressure line is 8.69MPa, the pore pressure value applied to the pore pressure injection hole 64 connected to the fourth pore pressure line is 8.69MPa, the pore pressure value applied to the pore pressure injection hole 64 connected to the fifth pore pressure line is 8.70MPa, the pore pressure value applied to the pore pressure injection hole 64 connected to the sixth pore pressure line is 8.71MPa, the pore pressure value applied to the pore pressure injection hole 64 connected to the seventh pore pressure line is 8.72MPa, and the pore pressure value applied to the pore pressure injection hole 64 connected to the eighth pore pressure line is 8.72MPa, the pore pressure applied to the pore pressure injection hole 64 connected with the ninth pore pressure pipeline is 8.73MPa, the pore pressure applied to the pore pressure injection hole 64 connected with the tenth pore pressure pipeline is 8.74MPa), the pressure controller 42 controls the servo booster 41 to carry out secondary boosting on the injection medium used for applying the pore pressure after primary boosting, and the pore pressure injection hole 64 in the gasification cavity 30 applies the pore pressure to the coal seam 27 under the action of the injection medium used for applying the pore pressure after secondary boosting; when the pore pressure data collected by the pore pressure data monitoring part reaches the pore pressure value set by the pressure controller 42, the pore pressure is maintained at the set value;

carrying out pressure testing after applying confining pressure and pore pressure, wherein the confining pressure and the pore pressure are applied for 36h, the confining pressure change range is within +/-5%, the pore pressure change range is +/-5%, the pressure testing is qualified, and the subsequent step 3) is carried out if the pressure testing is qualified, and the step 1 is carried out again after the coal underground gasification pollution evaluation system is overhauled if the pressure testing is unqualified;

in the confining pressure and pore pressure applying process, collecting confining pressure data, pore pressure data, volume of injection medium used in the confining pressure applying process, flow rate of injection medium used in the confining pressure applying process, volume of injection medium used in the pore pressure applying process, and flow rate of injection medium used in the pore pressure applying process, specifically: the confining pressure data monitoring piece transmits the collected confining pressure data to the pressure controller 42, the pore pressure data monitoring piece transmits the collected pore pressure data to the pressure controller 42, theservo supercharger 41 feeds back the confining pressure, the flow rate, the volume and other data of the injection medium 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 quantity data, the flow rate data and the volume data to thecomputer 43 for storage and display;

3) simulated gasification of coal seam 27:

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

ignition of the coal seam at the first ignition location is carried out using an ignition unit with the coal seam 27 injected with an oxidizer (specifically, the heating wire in the first ignition location in the borehole 28 is operated by the ignition controller 9 and continues to be at 3m³Injecting oxygen as combustion improver at a small displacement per hour), injecting a gasification agent into the coal seam 27 for coal seam gasification after the coal seam 27 is confirmed to be ignited, and repeatedly performing the processes of coal seam ignition and the injection of the gasification agent into the coal seam 27 for coal seam gasification at the next ignition position when the heat value of the synthesis gas generated by the coal seam gasification is reduced to 70% of the initial heat value until the last ignition position completes the operations of coal seam ignition and the injection of the gasification agent into the coal seam 27 for coal seam gasification, thereby completing the simulation gasification process of the whole coal seam; the synthesis gas generated in the simulated gasification process of the coal seam 27 enters a synthesis gas unit for treatment and then is discharged, specifically, the generated synthesis gas passes through a cooler 45, a dust remover 46, a decoking device 47 and a sulfur remover 48 to respectively remove solid dust, tar and sulfur-containing toxic gas in the synthesis gas, then enters a combustion chamber 50 for synthesis gas combustion treatment, and the gas after the combustion treatment is discharged; wherein, the synthesis gas after being processed by the dust remover 46, the decoking device 47 and the sulfur remover 48 is subjected to component analysis and measurement once every 1-5 minutes by using a gas detection device 49 to determine combustible gas components in the synthesis gas and the components of the synthesis gasA calorific value;

the number of the ignition positions is 2, the ignition positions are sequentially arranged from the end of a synthesisgas production channel 25 to the end of a gasificationagent injection channel 10, and the distance between every two adjacent ignition positions is 0.8 m;

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

Collecting injection flow rate, pressure and temperature data of a gasification agent in the simulated gasification process of thecoal seam 27, collecting data by using a gas data collecting part, a temperature data collecting part, a stress strain data collecting part and a pore pressure data collecting part of a pollution evaluation device, and storing and analyzing the collected data in a data collectingunit computer 25; the method comprises the following steps of drawing a contour map of the volume and concentration of escaping gas according to a synthetic gas escaping detection result collected by a gas data collecting part, and calibrating escaping boundaries of different gases; the types of the escaped gas comprise CO and CO₂、CH₄And H₂；

Monitoring the oxygen concentration by using a gas data acquisition part in the simulated gasification process of thecoal seam 27, and immediately alarming and stopping the test once the oxygen concentration exceeds the explosion limit;

4) and (3) detecting sewage in the gasification cavity 30:

after the simulated gasification of thecoal seam 27 is finished, stopping injecting the gasification agent, purging the pollution evaluation device by using anitrogen cylinder 2, discharging the residual synthesis gas in the gasification cavityinner cylinder 16 of the pollution evaluation device on one hand, and cooling the temperature of the pollution evaluation device on the other hand; after the nitrogen purging is completed, opening a sewage detectionunit control valve 51, a high-pressure waterpump control valve 62 and an underground watertank control valve 60, injecting coal bed water in anunderground water tank 61 into awell hole 28 through a high-pressure water pump 59 to replace sewage in agasification cavity 30, wherein the pumping pressure is lower than the pore pressure of a coal bed and is 8MPa, the sewage displaced in thegasification cavity 30 is firstly settled through a settlingtank 52 to remove large-size solid residues and coal dust, and a waterquality detection device 56 performs water quality analysis on the sewage settled in thesettling tank 52 to obtain the types and content of organic and inorganic pollutants in the underground coal gasification sewage so as to realize the pollution evaluation of the underground coal gasification water;

the sewage after sedimentation treatment in thesedimentation tank 52 sequentially enters a groundwaterprimary purification device 53, a groundwatersecondary purification device 54 and a groundwatertertiary purification device 55 for graded sewage purification treatment, and the sewage after each grade of treatment is subjected to water quality detection by using a waterquality detection device 56, so that on one hand, the sewage after treatment test is simulated, and on the other hand, an experimental support is provided for optimization of the pollution treatment process;

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

5) the confining pressure, pore pressure unloading and pollution evaluation device is dissected:

treat thatgasification chamber 30 sewage detects and carry out confined pressure, pore pressure uninstallation after finishing, it is specific: closing the confiningpressure booster pump 38 and the porepressure booster pump 39, returning the confining pressure and the pore pressure to zero through the pressure controller 42, reducing the pressure value in thehydraulic rod 15 in the pollution evaluation device through theservo booster 41, and slowly releasing the acting force of thehydraulic rod 15 until the confining pressure value acquired by the confining pressure data monitoring part is zero, which indicates 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 piece is zero, indicating that the pore pressure is completely unloaded; after the confining pressure and the pore pressure are unloaded, cooling the pollution evaluation device for 12 hours, opening aleft end cover 31 of the pollution evaluation device and aleft end cover 33 of the gasification cavity, and carrying out dissection on the pollution evaluation device;

thereby completing the coal underground gasification pollution evaluation.

Example 4

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

Example 5

The embodiment provides a method for evaluating underground coal gasification pollution, and the methodThe method is different from the gasification test method provided by theembodiment 3 only in that the injected gasification agents are different, the flow rates of the gasification agents are different, and the injection modes of the gasification agents are different, the injected gasification agents in the embodiment are oxygen-enriched air and water vapor, and the injection of the gasification agents adopts two-stage injection: oxygen-enriched air is injected into the first section, the volume concentration of oxygen in the oxygen-enriched air is 40%, and the flow rate of a gasification agent is controlled to be 20m³The stage is mainly the coal oxidation combustion exothermic reaction; the second stage is filled with steam with a flow rate of 25m³The stage is mainly subjected to water gas reaction and methanation reaction; the two stages are repeated in sequence.

Example 6

The method provided by the embodiment is different from the gasification test method provided by theembodiment 3 only in the injected gasification agents and the flow rates of the gasification agents, the injected gasification agents are oxygen-enriched air and water vapor, the volume concentration of oxygen in the oxygen-enriched air is 40 percent, the mass ratio of the water vapor to the oxygen in the gasification agents is 3:12:1-4:1, and the flow rate of the gasification agents is controlled to be 25m³/h。

Claims (31)

1. The device comprises an experiment chamber, wherein the experiment chamber 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; 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, a confining pressure applying component is arranged in the cavity, and the confining pressure applying component is connected with a confining pressure pipeline;

the wall of the inner cylinder is provided with a pore pressure injection hole, and the pore pressure injection hole is connected with a pore pressure pipeline;

an experiment injection fluid channel and an experiment output fluid channel are arranged on the barrel bottom of the experiment cavity barrel body and/or the experiment cavity cover; the experiment injection fluid channel and the experiment production fluid channel are communicated with the inside of the experiment cavity inner cylinder.

2. The device according to claim 1, wherein the confining pressure applying component comprises a plurality of hydraulic rods, one end of each hydraulic rod is fixed on the inner wall of the outer cylinder, and the other end of each hydraulic rod acts on the outer wall of the inner cylinder;

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 connection between the hydraulic rod and the outer wall of the inner cylinder is realized in a manner that the hydraulic rod sliding head of the hydraulic rod is in sliding connection with the hydraulic rod sliding rail of the outer cylinder;

more preferably, 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 barrel through the hydraulic rod fixing base.

3. The device of claim 2, wherein the inner cylinder of the experiment cavity is a cuboid which is enclosed by 4 plates and is open at two ends; for each plate, only one end of the plate abuts against the plate surface of one plate adjacent to the plate, and the plate surface of the plate is used as an abutting plate surface of the other plate adjacent to the plate; each panel is able to slide along it against the panel surface.

4. The apparatus of claim 1, wherein,

the experiment chamber is further provided with a confining pressure data monitoring piece, and the confining pressure data monitoring piece is used for acquiring confining pressure data on a cylinder in the experiment chamber;

the experimental cabin is further provided with a pore pressure data monitoring piece, and the pore pressure data monitoring piece is used for acquiring pressure data of a pore pressure injection hole.

5. The apparatus of claim 1, wherein the laboratory is further provided with a laboratory housing, the laboratory housing being provided outside the laboratory chamber, the laboratory housing comprising a housing lid and a housing tub which are detachably connected;

preferably, the experiment chamber is further provided with a refractory brick, and the refractory brick is arranged in a cavity between the experiment chamber shell and the experiment chamber.

6. The device of claim 1, wherein the experiment chamber is provided with a data acquisition assembly, the data acquisition assembly comprises a gas data acquisition part, and the gas data acquisition part is used for acquiring CO and CO in the cylinder in the experiment chamber₂、CH₄、H₂At least one of a dissipation concentration and a dissipation amount of (a);

preferably, the gas data acquisition part is further used for acquiring the oxygen concentration in the inner barrel of the experiment cavity;

preferably, the gas data acquisition part comprises a gas detection sensor and a gas detection collector, the gas detection sensor is arranged inside the experiment chamber, the gas detection collector is arranged outside the experiment chamber, and the gas detection sensor is connected with the gas detection collector.

7. The device of claim 1 or 6, wherein the experimental chamber is further provided with a data acquisition assembly comprising at least one of a temperature data acquisition element, a stress-strain data acquisition element and a pore pressure data acquisition element; the temperature data acquisition part is used for acquiring temperature data of a sample to be detected loaded in the tube in the experimental cavity, the stress-strain data acquisition part is used for acquiring stress-strain data of the sample to be detected loaded in the tube in the experimental cavity, and the pore pressure data acquisition part is used for acquiring pore pressure of the sample to be detected loaded in the tube in the experimental cavity;

preferably, the temperature data acquisition part comprises a thermocouple and a temperature collector, the thermocouple is arranged inside the experiment chamber, the temperature collector is arranged outside the experiment chamber, and the thermocouple is connected with the temperature collector; the stress-strain data acquisition part comprises a stress-strain sensor and a stress-strain data acquisition unit, the stress-strain sensor is arranged in the experiment chamber, the stress-strain data acquisition unit is arranged outside the experiment chamber, and the stress-strain sensor is connected with the stress-strain data acquisition unit; the pore pressure data acquisition piece comprises a pressure sensor and a pressure collector, the pressure sensor is arranged in the experiment chamber, the pressure change collector is arranged outside the experiment chamber, and the pressure sensor is connected with the pressure collector.

8. The device of claim 6 or 7, wherein the laboratory chamber is provided with at least one data acquisition wiring channel for at least one of temperature data acquisition wiring, supply force strain data acquisition wiring, pore pressure data acquisition wiring, and gas data acquisition wiring.

9. The apparatus of claim 1, wherein the laboratory chamber is provided with at least two laboratory production fluid channels, wherein at least one laboratory production fluid channel is provided on the same end face of the laboratory chamber as the laboratory injection fluid channel, and wherein the end face of the at least one laboratory production fluid channel disposed on the laboratory chamber is opposite to the end face of the laboratory injection fluid channel disposed on the laboratory chamber.

10. The device according to any one of claims 1 to 3, wherein the confining pressure applying component can apply vertical acting force and horizontal acting force to the sample to be tested loaded in the tube in the laboratory cavity;

preferably, the confining pressure applying component for applying horizontal acting force and the confining pressure applying component for applying vertical acting force are respectively connected with different confining pressure injection pipelines so as to realize the respective control of the magnitude of the horizontal acting force and the magnitude of the vertical acting force.

11. The device according to claim 1, wherein the hole pressure injection hole can be used for applying hole pressure to the sample to be tested loaded in the barrel in the laboratory cavity in the horizontal direction;

preferably, the hole pressure injection holes with different heights are connected with different hole pressure injection pipelines so as to apply different hole pressures to the hole pressure injection holes with different heights.

12. The apparatus of claim 1, wherein,

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

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

the experimental cavity can bear the pressure of at least 35MPa and the high temperature of at least 1300 ℃ and realize sealing.

13. Use of the apparatus of any one of claims 1 to 12 as a pollution evaluation apparatus in underground coal gasification pollution evaluation.

14. A coal underground gasification pollution evaluation system comprises a pollution evaluation device, a gasification agent preparation unit, a confining pressure and pore pressure loading unit, a synthetic gas treatment unit, a sewage detection unit and an ignition unit;

the contamination evaluation device uses the device according to any one of claims 1 to 12;

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

15. The system for evaluating underground coal gasification pollution according to claim 14, wherein the gasification agent preparation unit can prepare at least one of three types of gasification agents, namely air, oxygen-enriched air and a mixed gas of the oxygen-enriched air and water vapor;

preferably, 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, wherein the oxygen flow control assembly is connected with the oxygen cylinder to control the supply flow of oxygen, the nitrogen flow control assembly is connected with the nitrogen cylinder 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;

more preferably, the gasifying agent preparation unit further comprises at least one of a pressure gauge for measuring the pressure of oxygen supplied from the oxygen cylinder and/or nitrogen supplied from the nitrogen cylinder and/or steam supplied from the steam generator and/or air supplied from the air compressor and/or the gasifying agent supplied, and a thermometer for measuring the temperature of oxygen supplied from the oxygen cylinder and/or nitrogen supplied from the nitrogen cylinder and/or steam supplied from the steam generator and/or air supplied from the air compressor and/or the gasifying agent supplied.

16. The coal underground gasification pollution evaluation system according to claim 14, wherein the sample to be detected loaded in the experiment cavity barrel of the pollution evaluation device comprises a coal bed, and the coal bed is prefabricated with well bores which are respectively communicated with the experiment injection fluid channel and the experiment production fluid channel;

preferably, a combustible screen or casing is arranged in the well hole to support the well hole;

preferably, the sample to be tested further comprises a top plate and a bottom plate, the top plate is arranged above the coal seam, and the bottom plate is arranged below the coal seam; more preferably, when the experiment chamber is provided with the gas data acquisition part, the gas data acquisition part is used for acquiring gas data of a coal bed and a roof in the experiment process, wherein the gas data comprises CO and CO₂、CH₄、H₂、O₂At least one of a dissipation concentration and a dissipation amount of (a); when the experiment chamber is provided with the 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 experiment process; when the experimental cabin is provided with the stress-strain data acquisition part, the stress-strain data acquisition part is used for acquiring the stress-strain data of the top plate; when the experiment chamber is provided with the pore pressure data acquisition part, the pore pressure data acquisition part is used for acquiring the pore pressure of the coal bed and/or the top plate.

17. The coal underground gasification pollution evaluation system of claim 14, 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, wherein the confining pressure liquid source tank and the pore pressure liquid source tank respectively provide an injection medium for confining pressure application and an injection medium for pore pressure application, 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;

preferably, the pollution evaluation device is provided with a confining pressure data monitoring piece and a pore pressure data monitoring piece, the confining pressure data monitoring piece is used for acquiring confining pressure data on a cylinder in a laboratory cavity, the pore pressure data monitoring piece is used for acquiring pressure data of a pore pressure injection hole, the confining pressure data monitoring piece and the pore pressure data monitoring piece are respectively connected with the pressure controller, and data acquired by the confining pressure data monitoring piece and the pore pressure data monitoring piece are transmitted to the pressure controller;

preferably, the confining pressure and pore pressure loading unit further comprises a computer, and the computer is connected with the pressure controller and is used for monitoring, acquiring and analyzing data of the confining pressure and pore pressure loading and unloading processes in real time.

18. The system for evaluating pollution caused by underground coal gasification according to claim 14, wherein the ignition unit comprises an ignition controller and a heating wire, the ignition controller is used as an ignition switch and used for controlling initial ignition and continuous backward ignition operation in a test process, and the heating wire is arranged in a sample to be tested loaded in the test chamber; 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.

19. The pollution evaluation system of underground coal gasification of claim 14, wherein when the experimental chamber of the pollution evaluation device is provided with at least one of a gas data collection element, a temperature data collection element, a stress-strain data collection element and a pore pressure data collection element, the pollution evaluation system further comprises a data collection unit, the data collection unit comprises a computer, and the computer is connected with at least one of the gas data collection element, the temperature data collection element, the stress-strain data collection element and the pore pressure data collection element and is used for storing and analyzing data collected by the data collection element connected with the computer.

20. The coal underground gasification pollution evaluation system of claim 14, wherein the syngas treatment unit comprises a dust collector, a coke remover, a sulfur remover and a combustion chamber, wherein the dust collector, the coke remover and the sulfur remover are all arranged in front of the combustion chamber; the device comprises a dust remover, a decoking device, a sulfur remover and a combustion chamber, wherein the dust remover is used for removing solid dust in the synthetic gas discharged from an experimental fluid output channel, the decoking device is used for removing tar in the synthetic gas, the sulfur remover is used for removing sulfur-containing toxic gas in the synthetic gas, and the combustion chamber is used for carrying out combustion treatment on the synthetic gas;

preferably, the synthesis gas treatment unit further comprises a gas detection device, and the gas detection device is used for analyzing and metering the components of the synthesis gas treated by the dust remover, the coke remover and the sulfur remover;

preferably, the syngas treatment unit further comprises a cooler disposed before the dust separator, the coke separator and the sulfur separator.

21. The underground coal gasification pollution evaluation system of claim 14, wherein the sewage detection unit comprises a water injection device and a water quality detection device, the water injection device is connected to the experiment injection fluid channel of the pollution evaluation device and is used for injecting water into the pollution evaluation device to displace sewage in the inner tube of the experiment cavity, and the water quality detection device is used for detecting the water quality of the sewage discharged from the inner tube of the experiment cavity of the pollution evaluation device;

preferably, the sewage detection unit further comprises a settling tank, the settling tank is connected with an experimental output fluid channel of the pollution evaluation device, and the water quality detection equipment is connected with the settling tank to detect sewage precipitated by the settling tank;

more preferably, the sewage detection unit comprises a sewage treatment device, the sewage purification equipment is connected with a water outlet of the settling tank, and the water quality detection equipment is further connected with the sewage purification equipment so as to detect the quality of sewage in the sewage purification process of the sewage purification equipment and after the sewage purification;

further preferably, the sewage purification device comprises a first-level groundwater purification device, a second-level groundwater purification device and a third-level groundwater purification device, and the water quality detection device is respectively connected with the first-level groundwater purification device, the second-level groundwater purification device and the third-level groundwater purification device to detect the quality of sewage purified by the first-level groundwater purification device, the second-level groundwater purification device and the third-level groundwater purification device.

22. An underground coal gasification pollution evaluation method which is performed by using the underground coal gasification pollution evaluation system of any one of claims 14 to 21, and comprises the following steps:

1) preparing a top plate, a bottom plate and a coal bed for a gasification test, arranging an electric heating wire in a well-type prefabricated well hole simulated in the coal bed according to needs and a primary ignition position, filling the bottom plate, the coal bed and the top plate into an inner cylinder of an experimental cavity from bottom to top in the sequence of bottom plate-coal bed-top plate, and connecting the underground coal gasification pollution evaluation system;

2) applying confining pressure and pore pressure according to confining pressure and pore pressure values of the coal seam in the simulated area;

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

4) and (3) detecting sewage in the gasification cavity: injecting water into the experimental cavity to displace sewage in the gasification cavity, and performing water quality detection on the displaced sewage to realize water pollution evaluation;

thereby completing the coal underground gasification pollution evaluation.

23. The method for evaluating coal underground gasification pollution according to claim 22, wherein the well type to be simulated is a U-shaped horizontal well, a single-hole well bore is prefabricated in a coal seam, and the experimental injection fluid channel and the experimental production fluid channel are respectively arranged at two corresponding ends of the inner cylinder of the experimental cavity;

preferably, a combustible screen and/or casing is run into a coal seam prepared wellbore to support the wellbore.

24. The method for evaluating underground coal gasification pollution according to claim 22,

the confining pressure application comprises the application of a vertical acting force and a horizontal acting force; the vertical acting force and the horizontal acting force are used for simulating overburden pressure and horizontal main stress;

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

25. The method for evaluating pollution of underground coal gasification according to claim 22, wherein the performing of coal seam simulation gasification comprises: the ignition unit is used for igniting the coal seam at a first ignition position under the condition that a combustion improver is injected into the coal seam, a gasifying agent is injected into the coal seam after the coal seam is ignited for coal seam gasification, when the heat value of synthetic gas generated by coal seam gasification is reduced to 65-75% of the initial heat value, the ignition and gasification operation of the coal seam is repeatedly carried out at the next ignition position until the ignition and gasification of the coal seam are finished at the last ignition position, and the simulation gasification process of the whole coal seam is finished; synthetic gas generated in the coal bed simulation gasification process enters a synthetic gas treatment unit for treatment and then is discharged; synthetic gas generated in the coal bed simulation gasification process enters a synthetic gas treatment unit for treatment and then is discharged;

preferably, the ignition position is arranged in order from a position far from the position where the gasification agent is injected to a position near the position where the gasification agent is injected.

26. The method for evaluating pollution of underground coal gasification according to claim 22, wherein the gasifying agent comprises: at least one of an air gasifying agent, an oxygen-enriched air gasifying agent and an oxygen-enriched air and steam gasifying agent;

preferably, when the gasification agent is oxygen-enriched air and steam gasification agent, the gasification agent is injected in two-stage injection or one-stage injection; wherein,

the two-stage implant comprises: oxygen-enriched air is injected into the first section, the volume concentration of oxygen in the oxygen-enriched air is 21-50%, and the oxygen-enriched air flow rate is preferably 0-30m³H; the second stage is filled with steam at a flow rate of 0-30m³H; the two stages are sequentially and repeatedly carried out;

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

27. The underground coal gasification pollution evaluation method according to claim 22, wherein mounting holes for the gas data collection members are prefabricated in the roof and/or floor and/or coal seam for gasification pollution evaluation, and the gas data collection members are mounted in the roof and/or floor and/or coal seam for gasification pollution evaluation;

preferably, in the coal bed simulation gasification process in the step 3), a gas data acquisition part is used for detecting the loss of the synthesis gas;

preferably, during the coal seam simulation gasification process in the step 3), monitoring the oxygen concentration by using the gas data acquisition part.

28. The method for evaluating underground coal gasification pollution according to claim 22,

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 a gasification experiment, 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 the gasification experiment; preferably, in the coal bed simulated gasification process in the step 3), a temperature data acquisition part, a stress strain data acquisition part and a pore pressure data acquisition part are used for data acquisition;

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

and 3) acquiring the injection flow rate, pressure and temperature data of the gasifying agent in the step 3).

29. The method for evaluating underground coal gasification pollution according to claim 22, wherein the detection of the sewage in the gasification chamber further comprises purifying the displaced sewage and detecting the quality of the sewage during and after the purification.

30. The method for evaluating underground coal gasification pollution according to claim 22,

analyzing and metering the components of the synthesis gas by using a gas chromatograph in the synthesis gas processing unit, and determining combustible gas components in the synthesis gas and the heat value of the synthesis gas;

the method for processing the synthetic gas generated in the coal bed simulated gasification process in the synthetic gas processing unit comprises the following steps: the generated synthesis gas is subjected to dust removal, coke removal and sulfur removal to remove solid dust, tar and sulfur-containing toxic gas in the synthesis gas respectively, then the synthesis gas enters a combustion chamber to be subjected to synthesis gas combustion treatment, and the gas after the combustion treatment is discharged.

31. The method for evaluating coal underground gasification pollution according to claim 22, wherein sand is filled between the coal seam and the inner wall of the inner cylinder of the experimental cavity.

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