CN113403098A - Dry coke-discharging self-heating type aboveground dry distillation process for oil shale - Google Patents

Abstract

The invention discloses a dry coke-discharging self-heating type aboveground dry distillation process for oil shale, which introduces an exothermic alkane oxidation cracking technology into the dry distillation of the oil shale and simultaneously adopts H₂The semicoke generated after the dry distillation is cooled by the aid of the O, the water is gasified after absorbing the semicoke heat and enters the oil shale dry distillation section, so that the water content of the semicoke is not increased, and the cooled semicoke can be discharged by a dry method; exothermic reaction/H by coupled oxidative cracking in crude oil distillation stage₂O absorbs heat, so that the oil shale pyrolysis can release a large amount of heat to provide heat required by dry distillation, high-temperature heat carrier gas (smoke) added outside is replaced, the gas amount in the dry distillation furnace is reduced, the risk of gas leakage at a dry-method coke discharge position is reduced, water can improve the distribution of heat and materials in the furnace through the actions of heat absorption, mass transfer, heat transfer and the like, the phenomenon that the dry distillation furnace is locally heated up too high, too fast and coked is avoided, the oil shale dry distillation is prevented from being ignited, the overhigh temperature in the dry distillation furnace is suppressed, and the temperature in the whole dry distillation furnace is controlledAnd the temperature is lower than 550 ℃, so that secondary reaction and coking of oil gas are reduced.

Description

Dry coke-discharging self-heating type aboveground dry distillation process for oil shale

Technical Field

The invention relates to the technical field of aboveground dry distillation of oil shale, in particular to a dry-coke-discharging self-heating aboveground dry distillation process of oil shale.

Background

Oil shale is an unconventional fossil fuel resource, has huge global reserves, and is second to coal in fossil fuel resources according to calorific value. Organic matters contained in the oil shale can be subjected to dry distillation to obtain shale oil similar to crude oil, and the shale oil can be used as an important petroleum supplementary energy source. Oil shale organic matter can be extracted from oil shale ore only through dry distillation (pyrolysis), wherein the dry distillation of the oil shale generally refers to a process of heating the oil shale to about 500 ℃ under the condition of isolating air, so that the organic matter with a macromolecular structure in the oil shale is pyrolyzed to generate oil and gas. The dry distillation technology of oil shale is divided into an aboveground process and an underground process in terms of modes. The aboveground technology refers to a method of transporting oil shale ore from underground mining to the ground and then sending the oil shale ore into a dry distillation furnace for dry distillation. The underground technology is also called as in-situ dry distillation, namely the oil shale is directly subjected to dry distillation in an underground heating ore bed without being mined, and the underground technology is difficult to be practically applied at present. The above-ground technology is divided into a gas heat carrier method and a solid heat carrier method. The domestic solid heat carrier autonomous dry distillation technology is in the experimental stage, and no substantial progress is made by introducing foreign advanced technology.

However, the gas heat carrier method has a serious problem that solid residues (namely semicoke by-products) left after oil shale is subjected to dry distillation and oil refining cannot be utilized, the gas heat carrier methods adopted at home and abroad mostly adopt a wet coke discharging mode, and the semicoke energy cannot be effectively utilized. The semicoke is used as a main byproduct of the dry distillation of the oil shale, contains organic components and fixed carbon and has a certain calorific value. At present, the common method is to uniformly stack and discard as waste, so that the waste is rarely utilized, a large amount of land is occupied, the environment is polluted, and the waste of energy is caused. The semi-coke also contains water-soluble phenolic compounds, semi-volatile substances, polycyclic aromatic hydrocarbons and other toxic pollutants, and exudates formed in the process of open air placing seriously threaten underground water and cause serious pollution to the environment. The semicoke treatment problem is one of the main problems restricting the development of the oil industry by dry distillation of oil shale.

Therefore, the problem that the semicoke cannot be utilized by the gas heat carrier dry distillation technology needs to be solved urgently, and the dry coke discharging technology needs to be applied to the gas heat carrier dry distillation technology. The semicoke discharged by the dry coke discharging mode can be directly sent to a circulating fluidized bed boiler for combustion power generation without processes such as drying, the energy consumed by drying is saved, the process is simplified, and the burned boiler ash can also be sent to a building material factory for manufacturing building materials such as cement, building blocks, ceramsite and the like. Thus, the latent heat of the semicoke is fully utilized, and the harm to the environment is eliminated.

In addition, the operation difficulty of extracting the solid organic matters in the oil shale in an 'oil' form through dry distillation is high, a large amount of energy is needed to heat ores with the oil content of less than 10% so that the macromolecular organic matters in the ores are pyrolyzed into gas (namely dry distillation), and the pyrolysis gas is condensed to obtain shale oil. For example, in the above-ground technology, hot carrier gas is commonly used for heating oil shale, because the distillation end point of the dry distillation is about 500 ℃ and the cracking is an endothermic reaction, the hot carrier gas is generally heated to over 700 ℃ to enter a dry distillation furnace, and some process temperatures can reach as high as 1000 ℃ so that the shale oil is cracked or coked for the second time. In summary, the high energy input of the retorting process is a main obstacle to the utilization of oil shale resources, and is a main technical barrier that oil shale reserves are huge but not become a mainstream energy source.

Therefore, it is urgently required to develop an aboveground distillation process to solve the above problems.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provide the dry-coke-discharging self-heating type aboveground dry distillation process for the oil shale, which has the advantages of simple process, easiness in operation, energy and water conservation, higher resource utilization rate, less three-waste discharge and remarkable environmental benefit.

In order to achieve the purpose, the invention is implemented according to the following technical scheme:

a dry coke-discharging self-heating aboveground dry distillation process for oil shale comprises the following steps:

s1, crushing and preheating the oil shale raw material, adding the crushed and preheated oil shale raw material into a retort furnace from a feed inlet at the top end of the retort furnace, heating the oil shale raw material in the retort furnace to 200-350 ℃, and introducing normal-temperature oxygen-containing gas into the retort furnace; or directly introducing oxygen-containing gas at 200-350 ℃; after the oil shale raw material is contacted with the oxygen-containing gas, the oil shale raw material generates low-temperature oxidation reaction in the retort furnace, the heat released by the oxidation reaction is used for heating the oil shale raw material in the retort furnace, the temperature in the retort furnace rises, the retorting starts, and the normal-temperature oxygen-containing gas is continuously introduced into the retort furnace;

s2, introducing H into the dry distillation furnace₂O, regulation of O₂And H₂The introduction amount of O ensures that the temperature in the dry distillation furnace stably rises and is kept between 450 and 550 ℃;

s3, discharging oil gas generated by dry distillation from the upper part of the dry distillation furnace, and allowing the oil gas to enter an oil collecting system for oil collection to obtain shale oil and gas;

s4, introducing water into the lower part of the retort, allowing the water to contact with the oil shale semi-coke material generated after dry distillation for heat exchange and evaporation to form water vapor, allowing the water vapor to enter the upper dry distillation section, discharging the cooled oil shale semi-coke material into a semi-coke pool, and discharging the cooled oil shale semi-coke material out of the retort;

s5, repeating the steps S1-S4, and realizing continuous dry distillation of the oil shale.

Further, in step S1, the hot oil shale material is pre-heated by the waste flue gas exhausted from the heating furnace.

Further, the oxygen-containing gas is air or air without nitrogen. In the actual dry distillation process, the use of the air for removing nitrogen is beneficial, the air for removing nitrogen is obtained by removing the nitrogen from the air by adopting an air separator, and the oxygen can promote the organic matter of the oil shale to pyrolyze and produce the oil and reduce the N₂The content is beneficial to the treatment of subsequent oil gas products, because the oil gas generated by dry distillation is mixed with a large amount of carrier gas, the oil gas must be condensed simultaneously when being condensed to collect oilOil gas and a large amount of carrier gas make the condensation difficult to collect oil, a certain amount of oil gas can not be condensed, the oil yield is reduced, and N is removed₂The gas means that the treatment gas quantity at the dry distillation outlet is greatly reduced and the oil content proportion of the outlet gas is obviously improved, the oil recovery and oil condensation recovery system is simplified, the oil recovery efficiency is improved, the oil recovery difficulty is reduced, and meanwhile, the calorific value of a gas product after oil recovery is also improved.

Further, in the step S4, the discharged semicoke is used as a fuel to be sufficiently combusted to generate heat or generate electricity, and a part of the heat generated by the combustion is fed to the retort.

Compared with the prior art, the invention has the following beneficial effects:

1. the dry-process coke discharging can be realized, the dry semicoke discharged after the dry distillation of the oil shale is easy to be used as a solid fuel, the dry semicoke can be fully combusted to provide a large amount of heat, and the shale ash generated after the semicoke is fully combusted can be used as a building material, so that the high-efficiency utilization of resources is realized, organic toxic pollutants such as polycyclic aromatic hydrocarbon and the like in the semicoke are eliminated, and the environmental pollution is avoided; not only greatly reduces the heat consumption of dry distillation oil refining and simplifies the process, but also saves water by about 70 to 85 percent compared with the traditional wet-process coke extraction.

2. The dry-coke-discharging self-heating aboveground dry distillation method for the oil shale can generate heat in situ, achieve self-sufficiency of heat, has strong adaptability to raw material grade, can treat high-grade and low-grade oil shale, can control the highest temperature in a dry distillation furnace to be below 550 ℃, and avoids secondary cracking and coking of oil caused by overhigh temperature.

3. The dry coke-discharging self-heating aboveground dry distillation method for the oil shale can solve the problems of complex dry distillation system of the oil shale, resource waste, serious environmental pollution and the like; has the advantages of simple process, easy operation, energy and water conservation, higher resource utilization rate, less three-waste discharge, obvious environmental benefit and the like.

Drawings

FIG. 1 is a schematic diagram of the principle of the oil shale dry-discharge coke-drying distillation process of the present invention.

FIG. 2 is a schematic diagram comparing the process of the present invention with a conventional gas heat carrier process.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. The specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

Because the oil shale needs to be heated to more than 500 ℃ for dry distillation of the oil shale, and the cracking of the oil shale is an endothermic reaction, the existing gas heat carrier process at home and abroad directly heats the oil shale by using a large amount of high-temperature flue gas (more than 700 ℃, sometimes as high as 1000 ℃), so that the gas amount in a dry distillation furnace is very large, and gas leakage is easily caused when a dry coke discharging process is adopted, so most of the gas heat carrier processes can only discharge semicoke in a wet coke state by adopting a water sealing method, and in addition, the high-temperature heat carrier gas can also lead oil gas to be cracked secondarily or coked.

In order to solve the above problems, the present invention will be described in detail by the following two examples.

Example 1

As shown in fig. 1, the present embodiment provides a dry-coke-discharging self-heating aboveground retorting process for oil shale, comprising the following steps:

s1, crushing the oil shale raw material, preheating to 40-70 ℃ by using waste flue gas discharged by a heating furnace, and then sending into a retort furnace;

s2, continuously adding the preheated dry distillation raw material from a feeding hole at the top end of the dry distillation furnace, and introducing normal-temperature oxygen-containing gas into the dry distillation furnace when the oil shale raw material in the dry distillation furnace is heated to 200-350 ℃; after the oil shale raw material is contacted with the oxygen-containing gas, the oil shale raw material generates low-temperature oxidation reaction in the retort furnace, the heat released by the oxidation reaction is used for heating the oil shale raw material in the retort furnace, the temperature in the retort furnace rises, the retorting starts, and the normal-temperature oxygen-containing gas is continuously introduced into the retort furnace;

s3, introducing H into the dry distillation furnace₂O, the temperature in the retort is stably raised, the heat is uniformly distributed, the local overheating is avoided, and meanwhile, the steam water can accelerate the oil gas production generated by the pyrolysis through the blowing and clamping effectsThe material is quickly carried out of the retort to reduce secondary reaction and coking; regulation of O₂And H₂The introduction amount of O (if the temperature is too high or the temperature rises too fast, the O can be adjusted to be low₂/H₂The proportion of O can be increased, otherwise₂/H₂The proportion of O) is adopted, so that the temperature in the retort is stably raised and kept between 450 and 550 ℃, local overheating and ignition are avoided, secondary reaction and coking of generated oil gas are prevented, stable operation of dry distillation is ensured, and thorough dry distillation of the oil shale raw material is realized;

s4, discharging oil gas generated by dry distillation from the upper part of the dry distillation furnace, allowing the oil gas to enter an oil collecting system for oil collection, performing oil-gas-water separation after the oil gas is collected by a cooling tower and an electric catcher to obtain shale oil, gas and water, allowing the shale oil to enter a storage tank, allowing the water to enter a circulating water tank, and allowing the gas to serve as fuel for a heating furnace or as fuel gas for power generation;

s5, introducing water into the lower part of the retort, allowing the water to contact with an oil shale semi-coke material (with the temperature of 500-550 ℃) generated after dry distillation for heat exchange and evaporation to form water vapor, introducing the water vapor into the upper dry distillation section, discharging the cooled oil shale semi-coke material (with the temperature of less than 300 ℃) into a semi-coke pool, and discharging the cooled oil shale semi-coke material out of the retort; the oil shale semi-coke material discharged by the dry method is used as fuel to be fully combusted, part of heat generated by combustion can be sent into a retort furnace, and shale ash generated after combustion can be used as building material;

s6, repeating the steps S2-S5, and realizing continuous dry distillation of the oil shale.

Example 2

The difference from the example 1 is that in the step S2, the oil shale raw material in the retort is not heated, the oxygen-containing gas at 200 to 350 ℃ is directly introduced, the low-temperature oxidation reaction occurs in the retort, and the oil shale raw material is changed into the normal-temperature air after the start of the retort to realize the continuous operation.

The principle of the dry coke-discharging self-heating type oil shale dry distillation method is as follows: the patent introduces the exothermic alkoxylation cracking technology into the dry distillation of the oil shale and simultaneously passes through H₂With the aid of O, semicoke generated after dry distillation is cooled by water, the water is gasified after absorbing the semicoke heat and enters an oil shale dry distillation section, so that the water content of the semicoke is not increased, and the cooled semicoke can be discharged by a dry method; by coupled oxidative cracking in the dry distillation sectionexotherm/H₂O absorbs heat, so that the oil shale pyrolysis can release a large amount of heat to provide heat required by dry distillation, high-temperature heat carrier gas (smoke) added outside is replaced, the gas amount in the dry distillation furnace is reduced, the risk of gas leakage at a dry coke discharging position is reduced, the water can improve the distribution of heat and materials in the dry distillation furnace through the actions of heat absorption, mass transfer, heat transfer and the like, the phenomenon that the dry distillation furnace is locally heated up too high, too fast and coked is avoided, the oil shale dry distillation is prevented from being ignited, the temperature in the whole dry distillation furnace is reduced to be lower than 500-550 ℃ (low-temperature dry distillation) due to the fact that the temperature in the dry distillation furnace is too high, and the water can also accelerate oil gas products generated by pyrolysis to be rapidly taken out of the dry distillation furnace through the actions of blowing and entrainment so as to reduce secondary reaction and coking of the oil gas products.

It should be noted that the dry coke-discharging self-heating dry distillation process of the invention is also applicable to solid fuels such as coal and the like.

The technical solution of the present invention is not limited to the limitations of the above specific embodiments, and all technical modifications made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims (4)

1. The dry coke-discharging self-heating type aboveground dry distillation process for the oil shale is characterized by comprising the following steps of:

s1, crushing and preheating the oil shale raw material, adding the crushed and preheated oil shale raw material into a retort furnace from a feed inlet at the top end of the retort furnace, heating the oil shale raw material in the retort furnace to 200-350 ℃, and introducing normal-temperature oxygen-containing gas into the retort furnace; or directly introducing oxygen-containing gas at 200-350 ℃; after the oil shale raw material is contacted with the oxygen-containing gas, the oil shale raw material generates low-temperature oxidation reaction in the retort furnace, the heat released by the oxidation reaction is used for heating the oil shale raw material in the retort furnace, the temperature in the retort furnace rises, the retorting starts, and the normal-temperature oxygen-containing gas is continuously introduced into the retort furnace;

s2, introducing H into the dry distillation furnace₂O, regulation of O₂And H₂The introduction amount of O ensures that the temperature in the dry distillation furnace stably rises and is kept between 450 and 550 ℃;

s3, discharging oil gas generated by dry distillation from the upper part of the dry distillation furnace, and allowing the oil gas to enter an oil collecting system for oil collection to obtain shale oil and gas;

s4, introducing water into the lower part of the retort, allowing the water to contact with the oil shale semi-coke material generated after dry distillation for heat exchange and evaporation to form water vapor, allowing the water vapor to enter the upper dry distillation section, discharging the cooled oil shale semi-coke material into a semi-coke pool, and discharging the cooled oil shale semi-coke material out of the retort;

s5, repeating the steps S1-S4, and realizing continuous dry distillation of the oil shale.

2. The dry-coke-discharging autothermal oil shale aboveground retorting process of claim 1, wherein the oxygen-containing gas is air or air without nitrogen.

3. The dry-coke-discharging autothermal oil shale aboveground retorting process of claim 1, wherein the discharged gas obtained in the step S3 is used as a fuel for a heating furnace.

4. The dry-coke-discharging autothermal oil shale ground retorting process of claim 1, wherein in step S4, the discharged semicoke is used as fuel to fully combust to generate heat or electricity, and a part of the heat generated by combustion is fed into the retort.

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