In-situ pyrolysis system and method for semi-coke slow oxidation heating of oil-rich coal

Abstract

The application discloses a semi-coke slow oxidation heating oil-rich coal in-situ pyrolysis system and method, and belongs to the field of coal pyrolysis technology. The in-situ pyrolysis system comprises adjacent pyrolysis semi-coke blocks and oil-rich coal blocks. The oil-rich coal blocks are excavated with pyrolysis injection wells and pyrolysis output wells. After the pyrolysis of the oil-rich coal blocks is completed, the semi-coke blocks are formed. The pyrolysis injection wells and the pyrolysis output wells are converted into slow oxidation injection wells and slow oxidation output wells. The residual heat of the pyrolysis semi-coke blocks and the slow oxidation heat are used for the pyrolysis reaction of subsequent coal seams. Through the joint operation of adjacent blocks, the heat and material resources of the semi-coke blocks are fully utilized. The effective development of the pyrolysis semi-coke is realized. Meanwhile, a new in-situ heating feasible approach is provided. The oil-rich coal resources are fully utilized. No external heat energy needs to be additionally injected. The in-situ pyrolysis system has significant economic advantages. The CO2 generated by the semi-coke slow oxidation and the combustion of the pyrolysis product gas of the oil-rich coal is sealed in the pyrolysis semi-coke blocks. The carbon emission reduction is effectively realized. The in-situ pyrolysis system has significant environmental advantages.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of boilers, relates to the technical field of gas heating and flue gas waste heat recovery, and particularly relates to a semi-coke slow oxidation heating in-situ pyrolysis system and method for oil-rich coal. BACKGROUND

[0002] Oil-rich coal is a type of coal with a tar content of 7-12%, and research on using coal-to-oil technology to improve oil and gas production has been extensively and deeply discussed. However, the traditional coal mining and utilization process causes serious environmental pollution, resource waste, personnel casualties and other problems. Based on this, in recent years, a new concept of oil-rich coal in-situ pyrolysis has been proposed, that is, directly heating oil-rich coal in-situ to generate oil and gas products and extract them to the ground. The development and application of oil-rich coal in-situ pyrolysis technology provides a broad application prospect for oil and gas supply.

[0003] Common in-situ heating methods include conduction heating, convection heating and radiation heating. Regardless of the heating method, a large amount of external energy needs to be injected, resulting in huge economic costs. Semi-coke is one of the final products formed by in-situ pyrolysis of oil-rich coal. After the oil and gas products are pyrolyzed from the oil-rich coal, the remaining solid semi-coke remains in the underground to form a huge carbon matrix, and the abandonment of semi-coke will cause resource waste. By using the waste heat of the semi-coke layer and its slow oxidation reaction to heat the subsequent coal layer, the economic input can be significantly reduced, the joint operation of adjacent plots can be realized, and the semi-coke layer resources can be fully utilized. Therefore, it is of great practical significance to develop a semi-coke slow oxidation heating in-situ pyrolysis system and method for oil-rich coal. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a semi-coke slow oxidation heating in-situ pyrolysis system and method for oil-rich coal, which realizes the full and sufficient utilization of plot resources and the joint operation of adjacent plots, and effectively reduces the economic input.

[0005] The present application is achieved by the following technical solutions:

[0006] A semi-coke slow oxidation heating in-situ pyrolysis system for oil-rich coal comprises a plurality of adjacent oil-rich coal plots, and a pyrolysis injection well and a pyrolysis output well are excavated in the oil-rich coal plot; after the pyrolysis of the oil-rich coal plot is completed, a pyrolysis semi-coke plot is formed, and the pyrolysis injection well and the pyrolysis output well are converted into a slow oxidation injection well and a slow oxidation output well;

[0007] The slow oxidation injection well inlet of the pyrolysis semi-coke block is provided with a blower for injecting air into the pyrolysis semi-coke layer; the slow oxidation output well outlet of the first pyrolysis semi-coke block is communicated with the pyrolysis injection well inlet of the adjacent first oil-rich coal block through a pipeline, for injecting the oxidation products of the slow oxidation reaction of the first pyrolysis semi-coke block into the first oil-rich coal block; the pyrolysis output well outlet of the first oil-rich coal block is sequentially connected with a heat exchanger, a gas-liquid separation device, the liquid phase outlet of the gas-liquid separation device is connected with an oil storage device, the gas phase outlet of the gas-liquid separation device is connected with a combustion power generation device, and the flue gas outlet of the combustion power generation device is connected with a CO2 separation device.

[0008] The air pumped by the blower enters the first pyrolysis semi-coke block, the high-temperature oxidation products of the slow oxidation reaction of the first pyrolysis semi-coke block flow out along the slow oxidation output well and then enter the adjacent oil-rich coal block to perform a pyrolysis reaction, the pyrolysis products and the gas not participating in the reaction flow out along the pyrolysis output well, enter the heat exchanger, are cooled by heat exchange with the air pumped by the blower, and then enter the gas-liquid separation device, the tar is separated and collected in the oil storage device, and the remaining mixed gas is sent to the combustion power generation device to perform a combustion reaction with the preheated air, the combustion flue gas enters the CO2 separation device, the separated CO2 is stored in the first pyrolysis semi-coke block after the slow oxidation reaction, and the remaining flue gas carrying the heat of the combustion reaction continues to be injected into the adjacent second pyrolysis semi-coke block not subjected to the slow oxidation reaction to participate in the next reaction.

[0009] Preferably, the pyrolysis injection well and the pyrolysis output well are excavated from the ground in the oil-rich coal block, and a pyrolysis horizontal well is excavated to communicate the pyrolysis injection well and the pyrolysis output well, the oil-rich coal block forms a pyrolysis semi-coke block after the pyrolysis is completed, and the pyrolysis injection well and the pyrolysis output well are converted into a slow oxidation injection well and a slow oxidation output well, and the pyrolysis horizontal well is converted into a slow oxidation horizontal well.

[0010] Preferably, the slow oxidation injection well and the slow oxidation output well are vertical shafts vertically extending from the ground to the pyrolysis semi-coke layer of the pyrolysis semi-coke block; and the pyrolysis injection well and the pyrolysis output well are vertical shafts vertically extending from the ground to the oil-rich coal layer of the oil-rich coal block.

[0011] Preferably, the slow oxidation injection well is located at the top of the triangle, and the slow oxidation output well is located at the circumcenter of the triangle; and the pyrolysis injection well is located at the top of the triangle, and the pyrolysis output well is located at the circumcenter of the triangle.

[0012] The in-situ pyrolysis method of semi-coke slow oxidation heating oil-rich coal, comprising the following steps:

[0013] 1) Injecting fracturing fluid into oil-rich coal seam along pyrolysis injection well of first oil-rich coal block to form a large number of irregular fracturing cracks;

[0014] 2) Pumping air into first pyrolysis semi-coke block along slow oxidation injection well by air blower, semi-coke layer of first pyrolysis semi-coke block retains pyrolysis residual heat, slow oxidation reaction occurs in air atmosphere, oxidation products flow out along slow oxidation output well and continue to flow into first oil-rich coal block along pyrolysis injection well, and pyrolysis reaction is started in oil-rich coal seam of first oil-rich coal block under the convection heating of high-temperature mixed gas;

[0015] 3) Pyrolysis products and mixed gas not involved in the reaction flow out along pyrolysis output well, enter heat exchanger, and after heat exchange and cooling with air pumped by air blower, enter gas-liquid separation device to obtain tar by condensation separation, and the separated pyrolysis gas, CO2 and N2 mixed gas are sent into combustion power generation device to participate in combustion reaction with preheated air, and the generated flue gas enters CO2 separation device to separate CO2 and seal it in first pyrolysis semi-coke block after slow oxidation reaction, and the remaining flue gas carrying combustion reaction heat continues to be injected into second pyrolysis semi-coke block 2 to participate in slow oxidation reaction.

[0016] Preferably, the atmosphere of slow oxidation reaction of first pyrolysis semi-coke block is air, the atmosphere of slow oxidation reaction of the remaining pyrolysis semi-coke block is air and combustion flue gas after separation of CO2, the atmosphere participating in pyrolysis reaction of first oil-rich coal block is N2 and CO2, and the atmosphere participating in pyrolysis reaction of the remaining oil-rich coal block is a mixture of N2, CO2 and flue gas.

[0017] Preferably, the CO2 generated by slow oxidation reaction of first pyrolysis semi-coke block and the CO2 generated by combustion power generation of first oil-rich coal block are all sealed in first pyrolysis semi-coke block after slow oxidation reaction.

[0018] Preferably, pyrolysis products and heat carried out by them are all sent into combustion power generation device for combustion reaction, and combustion power generation device is used to supply energy to air blower.

[0019] Preferably, the heat release intensity of slow oxidation reaction is changed by controlling the air injection rate of semi-coke layer, and then the in-situ pyrolysis oil / gas production rate of oil-rich coal is regulated.

[0020] The present application opens injection wells and output wells in oil-rich coal strata, uses the pyrolysis semi-coke strata residual heat and slow oxidation heat for the pyrolysis reaction of subsequent coal strata, fully utilizes the semi-coke layer heat and material resources through the joint operation of adjacent blocks, and realizes the effective development of the pyrolysis semi-coke. In addition, the entire system operation process fully utilizes the oil-rich coal resources, does not need to inject external heat energy, has significant economic advantages; the CO2 generated by the slow oxidation of semi-coke and the combustion of pyrolysis product gas of oil-rich coal for power generation is all sealed in the pyrolysis semi-coke block, effectively realizes carbon emission reduction, and has significant environmental advantages.

[0021] The present application sequentially develops oil-rich coal pyrolysis reaction and semi-coke slow oxidation reaction in blocks, after the current semi-coke block and oil-rich coal block are jointly mined, the oil-rich coal block is converted into a semi-coke block, the semi-coke pyrolysis residual heat and slow oxidation reaction heat are all used for the temperature rising pyrolysis of subsequent oil-rich coal strata, the operation process does not need to input external energy, and the semi-coke layer heat and material are fully utilized, and the oil-rich coal in-situ pyrolysis oil extraction mining mode is enriched.

[0022] The present application has at least the following beneficial technical effects:

[0023] (1) The pyrolysis residual heat of the semi-coke layer and the slow oxidation heat of the semi-coke layer are simultaneously used for the in-situ pyrolysis of subsequent oil-rich coal strata, the pyrolysis residual heat and material resources of the semi-coke layer are fully utilized, and the pyrolysis semi-coke layer is effectively developed.

[0024] (2) The oil-rich coal block is completely pyrolyzed into a pyrolysis semi-coke block, and continues to participate in the in-situ pyrolysis of the next oil-rich coal block, realizes the full and sufficient utilization of block resources and the joint operation of adjacent blocks.

[0025] (3) The system operation relies on stratum resources, does not need to inject external heat energy, and effectively reduces economic investment.

[0026] (4) The CO2 generated by the slow oxidation reaction of the semi-coke block and the CO2 generated by the combustion of the pyrolysis gas of the oil-rich coal block for power generation are all sealed in the pyrolysis semi-coke block after the slow oxidation reaction, realizes the CO2 emission reduction in the coal mining and utilization process, and effectively helps China's "double carbon" target.

[0027] (5) In the operation of the system, the pyrolysis products are combusted to generate electricity, and the combustion power generation device is used to supply energy to the fan, which effectively utilizes the pyrolysis product gas resources and saves costs. The injection well is arranged at the vertex of the equilateral triangle, the injection well is arranged at the vertex of the equilateral triangle, and the injected fluid can be uniformly pushed to the inside from three directions. The output well is arranged at the circumcenter of the triangle to maximize the displacement effect of the injection well. The distance from the circumcenter to the three vertices of the triangle is equal, and the reaction products are output along the shortest path or the most reasonable pressure gradient path. The circumcenter position can ensure that the fluid resistance in each direction is relatively balanced, so that the fluid does not appear to be preferentially reached in one direction during the convergence process, which is beneficial to improve the mining efficiency and recovery.

[0028] (6) The well arrangement mode of the stratum adopts an equilateral triangle, the injection well is arranged at the vertex of the equilateral triangle, and the output well is arranged at the circumcenter of the triangle, which reasonably utilizes the space resources and improves the utilization rate of coal mining.

[0029] (7) Fracturing fluid is injected along the pyrolysis injection well into the oil-rich coal stratum to form artificial fracturing cracks, which increases the permeability of the coal seam and is beneficial to the subsequent heat and mass transfer process, thereby further improving the in-situ mining rate of oil-rich coal.

[0030] (8) The slow oxidation of semi-coke is coupled with the in-situ pyrolysis, which enriches the in-situ pyrolysis mining mode of oil-rich coal and provides a new idea for oil extraction and clean utilization of oil-rich coal resources. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structural schematic diagram of the in-situ pyrolysis system of the slow oxidation of semi-coke for heating oil-rich coal according to the present application;

[0032] Figure 2 is a well arrangement structure top view of the in-situ pyrolysis system according to the present application;

[0033] The reference signs are explained as follows: 1 is a rock layer, 2 is a pyrolysis semi-coke layer, 3 is an oil-rich coal layer, 4 is a fracturing crack, 5 is a slow oxidation injection well, 6 is a slow oxidation output well, 7 is a slow oxidation horizontal well, 8 is a pyrolysis injection well, 9 is a pyrolysis output well, 10 is a pyrolysis horizontal well, 11 is air, 12 is a fan, 13 is a heat exchanger, 14 is a gas-liquid separation device, 15 is an oil storage device, 16 is a combustion power generation device, 17 is a CO2 separation device, 18 is CO2, 19 is a first pyrolysis semi-coke block, 20 is a first oil-rich coal block, and 21 is a second pyrolysis semi-coke block. DETAILED DESCRIPTION

[0034] The present application will be further described in detail below in conjunction with specific embodiments, which are an explanation of the present application rather than a limitation.

[0035] Reference is made toFigure 1 As shown, the in-situ pyrolysis system of the present application for slow oxidation heating of semi-coke and oil-rich coal includes a plurality of adjacent semi-coke blocks and oil-rich coal blocks which are combined to operate, and a fan 12, a heat exchanger 13, a gas-liquid separation device 14, an oil storage device 15, a combustion power generation device 16 and a CO2 separation device 17 arranged on the ground.

[0036] The semi-coke block includes a rock layer 1 and a semi-coke layer 2, and the oil-rich coal block includes a rock layer 1 and an oil-rich coal layer 3. The pyrolysis injection well 8 and the pyrolysis output well 9 are vertically excavated from the ground in the oil-rich coal block, and the pyrolysis horizontal well 10 is excavated to connect the pyrolysis injection well 8 and the pyrolysis output well 9. After the first semi-coke block 19 is pyrolyzed, the first oil-rich coal block 20 is formed, the pyrolysis injection well 8 and the pyrolysis output well 9 are converted into the slow oxidation injection well 5 and the slow oxidation output well 6, and the pyrolysis horizontal well 10 is converted into the slow oxidation horizontal well 7. The fan 12 is arranged in the slow oxidation injection well 5 of the semi-coke block to inject air 11 into the semi-coke layer 2.

[0037] The outlet of the slow oxidation output well 6 of the first semi-coke block 19 is connected to the inlet of the pyrolysis injection well 8 of the adjacent first oil-rich coal block 20 through a pipeline to inject the oxidation product of the first semi-coke block 19 in the air atmosphere into the first oil-rich coal block 20. The pyrolysis output well 9 of the first semi-coke block 19 is sequentially connected to the gas-liquid separation device 14, the combustion power generation device 16 and the CO2 separation device 17. The gas-liquid separation device 14 is connected to the oil storage device 15. The pyrolysis product of the first semi-coke block 19 and the unreacted N2 enter the heat exchanger 13, are cooled by heat exchange with the air pumped by the fan, and then are sent to the gas-liquid separation device 14. The tar obtained by condensation and separation is collected in the oil storage device 15. The mixed gas of the remaining pyrolysis gas, CO2 and N2 is sent to the combustion power generation device 16 to be combusted with the preheated air to generate flue gas which enters the CO2 separation device 17 to separate the CO2 which is sealed in the first semi-coke block 19 after the slow oxidation reaction. The remaining flue gas which carries the heat of the combustion reaction continues to be injected into the adjacent second semi-coke block 21 to participate in the slow oxidation reaction.

[0038] In the present application, the atmosphere of the slow oxidation reaction of the first semi-coke block 19 is air, the atmosphere of the slow oxidation reaction of the remaining semi-coke blocks is air and the combustion flue gas after the separation of CO2, the atmosphere of the pyrolysis reaction of the first oil-rich coal block 20 is N2 and CO2, and the atmosphere of the pyrolysis reaction of the remaining oil-rich coal blocks is a mixture of N2, CO2 and flue gas.

[0039] The fan 12 pumps the air 11 into the first pyrolysis semi-coke block 19, the pyrolysis semi-coke layer 2 retains the pyrolysis residual heat, and a slow oxidation reaction occurs in the air atmosphere, and the oxidation products and the like flow out along the slow oxidation output well 6 and then continue to enter the first oil-rich coal block 20 along the pyrolysis injection well 8, the oxidation products mainly include CO2 and N2 carrying a large amount of heat energy, the oil-rich coal layer 3 of the first oil-rich coal block 20 starts the pyrolysis reaction, the pyrolysis products and the unreacted N2 flow out along the pyrolysis output well 9, enter the heat exchanger 13 and exchange heat with the air, and then enter the gas-liquid separation device 14, the tar is separated and collected in the oil storage device 15, the mixed gas of the remaining pyrolysis gas, CO2 and N2 is sequentially sent into the combustion power generation device 16 and the CO2 separation device 17, the separated CO2 is obtained and is sealed in the first pyrolysis semi-coke block 19 after the slow oxidation reaction, and the remaining flue gas carrying the combustion reaction heat continues to be injected into the second pyrolysis semi-coke block 21.

[0040] The first semi-coke block 19 generates CO2 through the slow oxidation reaction, and the first oil-rich coal block 20 generates CO2 through the pyrolysis gas combustion power generation, and the CO2 from different sources is sealed in the first pyrolysis semi-coke block 20 after the slow oxidation reaction, and the subsequent blocks are the same.

[0041] Referring to Figure 2 As shown in the figure, the slow oxidation injection well 5 and the slow oxidation output well 6 in the pyrolysis semi-coke block are arranged in a triangular well pattern, the slow oxidation injection well 5 is located at the top of the triangle, and the slow oxidation output well 6 is located at the circumcenter of the triangle. Similarly, the pyrolysis injection well 8 and the pyrolysis output well 9 in the oil-rich coal block are arranged in a triangular well pattern, the pyrolysis injection well 8 is located at the top of the triangle, and the pyrolysis output well 9 is located at the circumcenter of the triangle.

[0042] The present application comprehensively considers the slow oxidation of the pyrolysis semi-coke, the pyrolysis of the oil-rich coal, the coupled operation of the semi-coke block and the oil-rich coal block, the utilization of system waste heat and the CO2 storage path, and combines the unique well arrangement mode, so that the pyrolysis waste heat of the semi-coke layer and the slow oxidation exothermic heat are used for the pyrolysis of the next oil-rich coal layer, the semi-coke heat and material are fully utilized, the heat energy providing path of the in-situ heating is enriched, and a new idea is provided for the mining mode of the oil extraction of the oil-rich coal in-situ pyrolysis.

[0043] The in-situ pyrolysis method of the semi-coke slow oxidation heating oil-rich coal of the present application comprises the following steps:

[0044] 1) The fracturing fluid is injected into the coal layer 3 along the pyrolysis injection well 8 of the first oil-rich coal block 20, and a large number of irregular fracturing cracks 4 are formed;

[0045] 2) air 11 is pumped by fan 12 into first pyrolysis semi-coke block 19 along slow oxidation injection well 5, semi-coke layer 2 retains pyrolysis residual heat, slow oxidation reaction occurs in air atmosphere, oxidation products and the like flow out along slow oxidation output well 6 and continue to enter first oil-rich coal block 20 along pyrolysis injection well 8, mainly including CO2 and N2 carrying a large amount of heat, oil-rich coal layer 3 starts pyrolysis reaction under the heating of high-temperature CO2 and N2 mixed gas convection;

[0046] 3) pyrolysis products and unreacted N2 flow out along pyrolysis output well 9, enter heat exchanger 13 to exchange heat with air, and then are sent into gas-liquid separation device 14, tar obtained by condensation separation is collected in oil storage device 15, and the mixed gas of remaining pyrolysis gas, CO2 and N2 is sent into combustion power generation device 16 to participate in combustion reaction with preheated air, the generated flue gas enters CO2 separation device 17, CO2 is separated and stored in first pyrolysis semi-coke block 19 after slow oxidation reaction, and the remaining flue gas carrying combustion reaction heat continues to be injected into second pyrolysis semi-coke block 21 to participate in slow oxidation reaction.

[0047] The application pumps air 11 by fan 12, injects air 11 into first pyrolysis semi-coke block 19 along slow oxidation injection well 5, semi-coke layer 2 retains pyrolysis residual heat, so that semi-coke has a controllable slow oxidation reaction in air atmosphere, oxidation products and unreacted N2 flow out along slow oxidation output well 6 and enter first oil-rich coal block 20 along pyrolysis injection well 8, mainly including CO2 and N2 carrying a large amount of heat, oil-rich coal layer 3 starts pyrolysis reaction under the heating of high-temperature CO2 and N2 mixed gas convection;

[0048] With the progress of in-situ pyrolysis reaction, pyrolysis products, CO2 and N2 flow out along pyrolysis output well 9, enter heat exchanger 13 to exchange heat with air pumped by fan 12, and then enter gas-liquid separation device 14, tar obtained by condensation separation is collected in oil storage device 15, the mixed gas of remaining pyrolysis gas, CO2 and N2 enters combustion power generation device 16 to participate in combustion reaction with preheated air, combustion power generation device 16 supplies power to fan 13, combustion flue gas enters CO2 separation device 17, CO2 is separated and stored in first pyrolysis semi-coke block 19 after slow oxidation reaction, and the remaining flue gas carrying combustion reaction heat continues to be injected into second pyrolysis semi-coke block 21 to participate in slow oxidation reaction.

Claims

1. A semi-coking, slow-oxidation, heat- enriched coal in-situ pyrolysis system, characterized by: The method comprises the following steps: a plurality of adjacent oil-rich coal blocks are included, and a pyrolysis injection well (8) and a pyrolysis output well (9) are arranged in the oil-rich coal block; after the oil-rich coal block is pyrolyzed, a pyrolysis semi-coke block is formed, and the pyrolysis injection well (8) and the pyrolysis output well (9) are converted into a slow oxidation injection well (5) and a slow oxidation output well (6); The slow oxidation injection well (5) and the slow oxidation output well (6) in the pyrolysis semi-coke block are arranged in a triangular well distribution mode, the slow oxidation injection well (5) is located at a vertex of the triangle, and the slow oxidation output well (6) is located at a circumcenter of the triangle; the pyrolysis injection well (8) and the pyrolysis output well (9) in the oil-rich coal block are arranged in a triangular well distribution mode, the pyrolysis injection well (8) is located at a vertex of the triangle, and the pyrolysis output well (9) is located at a circumcenter of the triangle; A fan (12) for injecting air (11) into the pyrolysis semi-coke layer (2) is arranged at the inlet of the slow oxidation injection well (5) in the pyrolysis semi-coke block; the outlet of the slow oxidation output well (6) of the first pyrolysis semi-coke block (19) is communicated with the inlet of the pyrolysis injection well (8) of the adjacent first oil-rich coal block (20) through a pipeline, so as to inject the oxidation product of the slow oxidation reaction of the first pyrolysis semi-coke block (19) into the first oil-rich coal block (20); the outlet of the pyrolysis output well (9) of the first oil-rich coal block (20) is sequentially connected with a heat exchanger (13), a gas-liquid separation device (14), the liquid phase outlet of the gas-liquid separation device (14) is connected with an oil storage device (15), the gas phase outlet of the gas-liquid separation device (14) is connected with a combustion power generation device (16), and the flue gas outlet of the combustion power generation device (16) is connected with a CO2 separation device (17); The fan (12) pumps the air (11) into the first pyrolysis semi-coke block, the high-temperature oxidation product of the slow oxidation reaction of the first pyrolysis semi-coke block flows out along the slow oxidation output well (6) and then enters the adjacent oil-rich coal block to perform a pyrolysis reaction, the pyrolysis product and the gas not participating in the reaction flow out along the pyrolysis output well (9) and then enter the heat exchanger (13), are cooled after heat exchange with the air pumped by the fan (12) and then enter the gas-liquid separation device (14), the tar is separated and collected in the oil storage device (15), the remaining mixed gas is sent into the combustion power generation device (16) to perform a combustion reaction with the preheated air, the combustion flue gas enters the CO2 separation device (17), the separated CO2 is stored in the first pyrolysis semi-coke block after the slow oxidation reaction, and the remaining flue gas carrying the heat of the combustion reaction continues to be injected into the second pyrolysis semi-coke block not subjected to the slow oxidation reaction to participate in the next reaction.

2. The semi-coking slow oxidation heating of oil-rich coal in-situ pyrolysis system according to claim 1, characterized in that: The pyrolysis injection well (8) and the pyrolysis output well (9) are excavated from the ground in the oil-rich coal block, and a pyrolysis horizontal well (10) is excavated to communicate the pyrolysis injection well (8) and the pyrolysis output well (9); after the oil-rich coal block is pyrolyzed, a pyrolysis semi-coke block is formed, the pyrolysis injection well (8) and the pyrolysis output well (9) are converted into a slow oxidation injection well (5) and a slow oxidation output well (6), and the pyrolysis horizontal well (10) is converted into a slow oxidation horizontal well (7).

3. The semi-coking slow oxidation heating of oil-rich coal in-situ pyrolysis system according to claim 2, characterized in that: The slow oxidation injection well (5) and the slow oxidation output well (6) are vertical shafts extending vertically from the ground to the pyrolysis semi-coke layer (2) of the pyrolysis semi-coke block, and the pyrolysis injection well (8) and the pyrolysis output well (9) are vertical shafts extending vertically from the ground to the oil-rich coal layer (3) of the oil-rich coal block.

4. The in situ retorting method of slow oxidation heating of semi-coke to enrich oil coal based on the in situ retorting system of claim 3, characterized in that The method comprises the following steps: 1) injecting a fracturing fluid into the oil-rich coal layer (3) along the pyrolysis injection well (8) of the first oil-rich coal block (20) to form a large number of irregular fracturing cracks (4); 2) pumping air (11) into the first pyrolysis semi-coke block (19) along the slow oxidation injection well (5) by a fan (12), the semi-coke layer (2) of the first pyrolysis semi-coke block (19) retains the pyrolysis residual heat, and a slow oxidation reaction occurs in the air atmosphere, the oxidation products flow out of the slow oxidation output well (6) and continue to flow into the first oil-rich coal block (20) along the pyrolysis injection well (8), and the high-temperature mixed gas is heated by convection to start a pyrolysis reaction in the oil-rich coal layer (3) of the first oil-rich coal block (20); 3) the pyrolysis products and the mixed gas not participating in the reaction flow out of the pyrolysis output well (9) and enter a heat exchanger, are cooled by heat exchange with the air pumped by the fan, and then enter a gas-liquid separation device (14) to obtain tar by condensation separation, and the separated pyrolysis gas, CO2 and N2 mixed gas are sent into a combustion power generation device (16) to participate in a combustion reaction with the preheated air, the generated flue gas enters a CO2 separation device (17) to separate CO2 and store the CO2 in the first pyrolysis semi-coke block (19) after the slow oxidation reaction, and the remaining flue gas carrying the heat of the combustion reaction continues to be injected into the second pyrolysis semi-coke block (21) to participate in the slow oxidation reaction.

5. The in situ pyrolysis process of slow oxidation of semi-coke to heat up oil-rich coal based pyrolysis system according to claim 4, characterized in that: The atmosphere of the slow oxidation reaction of the first pyrolysis semi-coke block (19) is air, the atmosphere of the slow oxidation reaction of the remaining pyrolysis semi-coke blocks is air and combustion flue gas after separation of CO2, the atmosphere participating in the pyrolysis reaction of the first oil-rich coal block (20) is N2 and CO2, and the atmosphere participating in the pyrolysis reaction of the remaining oil-rich coal blocks is a mixture of N2, CO2 and flue gas.

6. The in-situ pyrolysis process of slow oxidation of semi-coke to heat up oil-rich coal based pyrolysis system according to claim 4, characterized in that: The CO2 generated by the slow oxidation reaction of the first pyrolysis semi-coke block (19) and the CO2 generated by the combustion power generation of the pyrolysis gas of the first oil-rich coal block (20) are stored in the first pyrolysis semi-coke block (19) after the slow oxidation reaction.

7. The in situ pyrolysis process of slow oxidation of semi-coke to heat up oil-rich coal based pyrolysis system according to claim 6, characterized in that: The pyrolysis products and the heat carried out by the pyrolysis products are sent into the combustion power generation device (16) to perform a combustion reaction, and the combustion power generation device is used to supply energy to the fan.

8. The in-situ pyrolysis process of slow oxidation of semi-coke to heat up oil-rich coal based pyrolysis system according to claim 6, characterized in that: The slow oxidation reaction heat release intensity is changed by controlling the air injection rate of the semi-coke layer, and then the oil / gas production rate of the oil-rich coal in-situ pyrolysis is regulated.

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