Stratum grading and quality-grading utilization system and method for in-situ pyrolysis-semicoke gasification of oil-rich coal

Abstract

The invention discloses an oil-rich coal in-situ pyrolysis-semicoke gasification stratum grading and quality-grading utilization system and method. The grading and quality-grading utilization system comprises an air separation device, a first heat exchanger, a second heat exchanger and a combustion power generation device. A pyrolysis injection well and a pyrolysis output well are excavated in an oil-rich coal plot, a semi-coke plot is formed after in-situ pyrolysis and oil extraction of the oil-rich coal plot, the pyrolysis injection well and the pyrolysis output well serve as a gasification injection well and a gasification output well correspondingly, and stratum waste heat and gasification reaction heat of the semi-coke plot are used for a pyrolysis reaction of a next oil-rich coal plot. In-situ pyrolysis reactions of different plots are started in sequence, and oil and gas resources and reaction heat in oil-rich coal are extracted in sequence through combined operation of a pyrolysis semi-coke plot and an oil-rich coal plot in the whole process, so that resource graded and quality-divided utilization in the in-situ mining process is realized; the heat exchanger is adopted to sequentially carry out graded heat exchange on pyrolysis products, gradient utilization of heat energy is achieved, coal waste is avoided, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of coal utilization, and in particular relates to a stratum classification and quality classification utilization system and method for in-situ pyrolysis-semi-coke gasification of oil-rich coal. Background Art

[0002] Oil-rich coal is coal with a tar content of 7-12%. The huge reserves ensure the large-scale mining of oil-rich coal. The in-situ pyrolysis technology of oil-rich coal is a concept proposed in recent years. This technology produces oil and gas by heating the coal seam in situ, which can reduce the processes and equipment such as well construction, mining, washing and conversion. It is a major change in coal mining technology, and at the same time increases the supply of oil and gas, which has significant strategic significance.

[0003] After the in-situ pyrolysis of oil-rich coal, a huge semi-coke layer is generated, and there is a problem of insufficient utilization of land resources. In addition, the large accumulation of semi-coke also causes a serious waste of space resources, and its subsequent processing process cannot be ignored. As a high calorific value fuel, coal pyrolysis semi-coke will release a lot of heat after gasification. The combined operation of semi-coke gasification-oil-rich coal pyrolysis reaction can realize the graded and quality-based utilization of oil-rich coal land resources and effectively complete the subsequent development of semi-coke. Therefore, it is of great practical significance to develop a system and method for graded and quality-based utilization of strata for in-situ pyrolysis of oil-rich coal-semi-coke gasification. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a system and method for stratum graded and quality-differentiated utilization of oil-rich coal in situ pyrolysis and semi-coke gasification, so as to realize the graded and quality-differentiated utilization of resources in the in-situ mining process of oil-rich coal, avoid coal waste and reduce production costs.

[0005] The present invention is achieved through the following technical solutions:

[0006] A stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal, comprising an air separation device, a first heat exchanger, a second heat exchanger, and a combustion power generation device;

[0007] A pyrolysis injection well and a pyrolysis output well are excavated in the oil-rich coal plot. After the pyrolysis reaction is completed, the pyrolysis injection well and the pyrolysis output well are used as a gasification injection well and a gasification output well, respectively. An ignition device is provided at the bottom of the gasification injection well. The air is separated into low-temperature N2 and low-temperature O2 by providing an air separation device. The oxygen output port of the air separation device is connected to a first heat exchanger and a second heat exchanger, respectively. The first heat exchanger is used to preheat part of the oxygen and send it to the gasification injection well and into the pyrolysis semi-coke plot to start the gasification reaction of the semi-coke layer under the action of the ignition device. The second heat exchanger is used to preheat the remaining oxygen and send it to the combustion power generation device to participate in the combustion reaction.

[0008] The outlet of the gasification output well is connected to the combustion power generation device, the gasification product flows out of the gasification output well and enters the combustion power generation device, the smoke outlet of the combustion power generation device is connected to the inlet of the pyrolysis injection well, the high-temperature CO2 generated by the combustion power generation device enters the oil-rich coal block to start the in-situ pyrolysis reaction, the outlet of the pyrolysis output well is connected to the hot gas input port of the first heat exchanger, the cold gas outlet of the first heat exchanger is connected to the gas-liquid separation device, the liquid phase outlet of the gas-liquid separation device is connected to the oil storage device, the gas phase outlet of the gas-liquid separation device is connected to the CO2 separation device, the carbon dioxide output port of the CO2 separation device is connected to the hot gas inlet of the second heat exchanger, and the pyrolysis gas outlet of the CO2 separation device is connected to the injection well that forms a semi-coke block after the pyrolysis is completed.

[0009] Preferably, a temperature monitoring well is excavated between the gasification injection well and the gasification output well in the pyrolysis semi-coke plot; and a temperature monitoring well is excavated between the pyrolysis injection well and the pyrolysis output well in the oil-rich coal plot.

[0010] Preferably, a plurality of gasification horizontal wells are excavated at different depths in the pyrolysis semi-coke plot, and the gasification injection well and the gasification output well are connected through the gasification horizontal wells.

[0011] Preferably, a plurality of pyrolysis horizontal wells are excavated at different depths in the oil-coal-rich land, and the pyrolysis injection well and the pyrolysis output well are connected through the pyrolysis horizontal wells.

[0012] Preferably, a vertical well is excavated in the pyrolysis coke plot, the nitrogen outlet of the air separation device is connected to the inlet of the vertical well, and low-temperature N2 is injected into the pyrolysis coke plot to form a freezing wall.

[0013] Preferably, a vertical well is excavated in the oil-rich coal block, the cold gas outlet of the second heat exchanger is connected to the inlet of the vertical well, and low-temperature CO2 is injected into the oil-rich coal block to form a freezing wall.

[0014] Preferably, the combustion power generation device supplies energy to the air separation device.

[0015] Preferably, in the pyrolysis semi-coke plot, one group of gasification injection wells and gasification output wells are located at the vertices of one diagonal line of the quadrilateral, another group of gasification injection wells and gasification output wells are located at the vertices of another diagonal line of the quadrilateral, and the temperature monitoring well is located at the intersection of the two diagonals;

[0016] In the oil-rich coal block, one group of pyrolysis injection wells and pyrolysis output wells are located at the vertices of one diagonal of the quadrilateral, another group of pyrolysis injection wells and pyrolysis output wells are located at the vertices of the other diagonal of the quadrilateral, and the temperature monitoring well is located at the intersection of the two diagonals.

[0017] The method for utilizing oil-rich coal in situ by pyrolysis and semi-coke gasification in a stratum by graded quality and quality, comprises the following steps:

[0018] 1) The air separation device separates air into low-temperature N2 and low-temperature O2. Part of the low-temperature O2 passes through the first heat exchanger to exchange heat with the pyrolysis product and then enters the combustion power generation device to participate in the combustion reaction. The remaining low-temperature O2 passes through the second heat exchanger to exchange heat with the high-temperature CO2 separated by the CO2 separation device and then enters the pyrolysis semi-coke plot. The low-temperature N2 separated by the air separation device is continuously injected into the vertical well of the pyrolysis semi-coke plot;

[0019] 2) Entering the pyrolysis semi-coke plot through the gasification injection well, the semi-coke layer gasification reaction is started under the action of the ignition device at the downhole end of the gasification injection well, and the gasification product flows out from the gasification output well and enters the combustion power generation device to undergo a combustion reaction. The high-temperature CO2 generated by the combustion carries a large amount of heat through the pyrolysis injection well into the oil-rich coal plot, starting the in-situ pyrolysis reaction under the convection heating of the high-temperature fluid;

[0020] 3) The pyrolysis products are produced and flow out along the pyrolysis output well, passing through the first heat exchanger and the gas-liquid separation device in sequence. The pyrolysis tar obtained by condensation separation is collected in the oil storage device, and the mixed gas enters the CO2 separation device. The separated CO2 first passes through the second heat exchanger, and is injected into the vertical well of the oil-rich coal block after cooling to form a freezing wall. The remaining pyrolysis gas is injected into the semi-coke block formed after the pyrolysis is completed, and the gasification reaction is started after ignition.

[0021] Preferably, the starting source of the in-situ pyrolysis reaction of the current oil-rich coal block is the pyrolysis waste heat and gasification reaction heat of the previous semi-coke block; after the pyrolysis of the oil-rich coal block is completed to form a second semi-coke block, the pyrolysis gas is injected into the semi-coke layer and ignited to initiate the gasification reaction.

[0022] The present invention opens a pyrolysis injection well and a pyrolysis output well in the oil-rich coal block. After the coal seam is pyrolyzed in situ to extract oil, a semi-coke layer is formed. The heat of the gasification reaction of the pyrolysis semi-coke block is used for the pyrolysis reaction of the next oil-rich coal block. The whole process realizes the graded and quality-based utilization of resources in the in-situ mining process of oil-rich coal; each oil-rich coal block starts the in-situ pyrolysis reaction in turn without inputting external energy, making full use of the block resources. At the same time, a heat exchanger is used to perform graded heat exchange on the pyrolysis products in turn, realizing the cascade utilization of thermal energy. The oil-rich coal block is pyrolyzed to extract oil and gas resources. After the pyrolysis is completed to form a semi-coke block, the semi-coke is gasified to utilize the residual heat of the formation and the heat of the gasification reaction, realizing the graded and quality-based utilization of resources.

[0023] The present invention carries out pyrolysis reaction of oil-rich coal and gasification reaction of semi-coke on the plots of land in sequence. After the joint mining of the current semi-coke plot and the oil-rich coal plot is completed, the oil-rich coal plot is transformed into a semi-coke plot and continues to participate in the pyrolysis reaction of the next oil-rich coal plot. No additional external energy is required for the operation process, and the graded and quality-based utilization of resources in the in-situ mining process of oil-rich coal is effectively realized.

[0024] The present invention has at least the following beneficial technical effects:

[0025] (1) After the in-situ pyrolysis of the oil-rich coal block is complete, it is converted into a semi-coke layer block. At this time, the in-situ gasification reaction is continued on the block, which can realize the graded and quality-based utilization of resources in the in-situ mining process of the oil-rich coal, fully utilize the block resources, and avoid coal waste.

[0026] (2) After the in-situ pyrolysis of the current oil-rich coal block and the in-situ gasification of the upper semi-coke layer block are jointly operated, the semi-coke layer block is transformed into a semi-coke layer block, and the gasification reaction continues to participate in the in-situ pyrolysis of the next oil-rich coal block. No additional external energy is required, which reduces production costs and has great economic advantages.

[0027] (3) The pyrolysis products are heat exchanged with part of the low-temperature O2 after air separation through the first heat exchanger, and the pyrolysis gas combustion flue gas is heat exchanged with the remaining low-temperature O2 through the second heat exchanger. This process realizes the cascade utilization of the thermal energy of the pyrolysis products and avoids heat waste.

[0028] (4) The temperature monitoring wells in the pyrolysis semi-coke plot and the oil-rich coal plot can respectively monitor the pyrolysis temperature and gasification in real time, thereby regulating the intensity of the gasification reaction and keeping the pyrolysis reaction within the optimal oil extraction temperature range.

[0029] (5) After the pyrolysis reaction is completed, the semi-coke layer is immediately subjected to gasification reaction, which can also realize the recovery and utilization of the residual heat of the formation.

[0030] (6) The development and utilization of pyrolysis semi-coke plots is based on the in-situ pyrolysis well layout method. During the gasification process, there is no need to re-drill wells, which effectively controls the operating costs.

[0031] (7) During the operation of the system, the pyrolysis products are burned to generate electricity, and a combustion power generation device is used to supply energy to the air separation device, thereby effectively utilizing the pyrolysis product gas resources and saving costs.

[0032] (8) A quadrilateral well layout method is adopted, and the number of quadrilateral arrangements of injection wells and output wells can be arranged according to the actual distribution of coal seams, which fully utilizes space resources and improves the utilization rate of coal mining.

[0033] (9) Low-temperature N2 is continuously injected into the pyrolysis semi-coke plot, and low-temperature CO2 is continuously injected into the oil-rich coal plot. According to the operating characteristics of the system, different media are used to prepare freezing walls in different plots, which effectively prevents groundwater leakage during the in-situ reaction process.

[0034] (10) By connecting injection wells and output wells through horizontal wells of different depths dug in the land, in-situ development of shallow, medium and deep oil-rich coal is achieved; BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the stratum classification and quality classification utilization system of the oil-rich coal in-situ pyrolysis-semi-coke gasification of the present invention;

[0036] Figure 2 It is a top view of the well arrangement structure in the present invention;

[0037] Explanation of the accompanying drawings: 1 is a rock layer, 2 is a pyrolysis semi-coke layer, 3 is an oil-rich coal seam, 4 is a freezing wall, 5 is a gasification injection well, 6 is a gasification output well, 7 is a pyrolysis injection well, 8 is a pyrolysis output well, 9 is a temperature monitoring well, 10 is a gasification horizontal well, 11 is a pyrolysis horizontal well, 12 is an ignition device, 13 is air, 14 is an air separation device, 15 is low-temperature N2, 16 is part of the low-temperature O2, 17 is the remaining low-temperature O2, 18 is a combustion power generation device, 19 is high-temperature CO2, 20 is a first heat exchanger, 21 is preheated O2, 22 is a second heat exchanger, 23 is low-temperature CO2, 24 is O2 after heat exchange, 25 is a gas-liquid separation device, 26 is a CO2 separation device, 27 is an oil storage device, 28 is a pyrolysis semi-coke plot, 29 is an oil-rich coal plot, and 30 is a second semi-coke plot. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0039] See also Figure 1 As shown, the stratum classification and quality-differentiation utilization system of in-situ pyrolysis and semi-coke gasification of oil-rich coal of the present invention includes injection wells and output wells excavated in adjacent pyrolysis semi-coke plots 28 and oil-rich coal plots 29; the pyrolysis semi-coke plot 28 includes a rock layer 1 and a pyrolysis semi-coke layer 2, a gasification injection well 5 and a gasification output well 6 are excavated in the pyrolysis semi-coke plot 28, and a number of gasification horizontal wells 10 of different depths are excavated to connect the gasification injection well 5 and the gasification output well 6, and a temperature monitoring well 9 is excavated between the gasification injection well 5 and the gasification output well 6. The oil-rich coal plot 29 includes an oil-rich coal layer 3 and a rock layer, a pyrolysis injection well 7 and a pyrolysis output well 8 are excavated in the oil-rich coal plot 29, and a number of pyrolysis horizontal wells 11 of different depths are excavated to connect the pyrolysis injection well 7 and the pyrolysis output well 8, and a temperature monitoring well 9 is excavated between the pyrolysis injection well 7 and the pyrolysis output well 8. Temperature monitoring wells 9 are set in the pyrolysis semi-coke block 28 and the oil-rich coal block 29 to control the semi-coke gasification reaction and the oil-rich coal pyrolysis reaction in real time within the target temperature range.

[0040] An ignition device 12 is provided at the bottom of the gasification injection well 5, and an air separation device 14, a combustion power generation device 18, a first heat exchanger 20, a second heat exchanger 22, a gas-liquid separation device 25, a CO2 separation device 26 and an oil storage device 27 are provided on the ground. The air separation device 14 separates the air 13 into low-temperature N2 and low-temperature O2. The oxygen output port of the air separation device 14 is connected to the cold gas input ports of the first heat exchanger 20 and the second heat exchanger 22. The hot gas outlets of the first heat exchanger 20 and the second heat exchanger 22 are connected to the inlet of the gasification injection well 5 and the combustion power generation device 18 respectively. Part of the low-temperature O2 16 enters the combustion power generation device 18 to participate in the combustion reaction after being preheated by the first heat exchanger 20, and the remaining low-temperature O2 17 enters the pyrolysis semi-coke block 28 to participate in the gasification reaction after being heat exchanged by the second heat exchanger 22. The gasification reaction of the semi-coke layer is started under the action of the ignition device 12 at the lower end of the gasification injection well 5. The nitrogen outlet of the air separation device 14 is connected to a vertical well dug in the pyrolysis coke block 28, and low-temperature N2 15 is continuously injected into the pyrolysis coke block 28 to form a freezing wall 4.

[0041] The outlet of the gasification output well 6 is connected to the combustion power generation device 18, and the flue gas outlet of the combustion power generation device 18 is connected to the inlet of the pyrolysis injection well 7. The gasification product flows out of the gasification output well 6 and enters the combustion power generation device 18. The high-temperature CO219 generated by the combustion enters the oil-rich coal block 29 to start the in-situ pyrolysis reaction. The outlet of the pyrolysis output well 8 is connected to the hot gas input port of the first heat exchanger 20, and the cold gas outlet of the first heat exchanger 20 is connected to the gas-liquid separation device 25. The liquid phase outlet of the gas-liquid separation device 25 is connected to the oil storage device 27. The gas phase outlet of the gas-liquid separation device 25 is connected to the CO2 separation device 26. The carbon dioxide output port of the CO2 separation device 26 is connected to the hot gas inlet of the second heat exchanger 22. The cold gas outlet of the second heat exchanger 22 is connected to a vertical well excavated in the oil-rich coal block 29. The pyrolysis gas outlet of the CO2 separation device 26 is connected to the injection well for forming the second semi-coke block 30 after the pyrolysis is completed. The pyrolysis products pass through the first heat exchanger 20 and the gas-liquid separation device 25 in sequence, and the condensed pyrolysis tar is collected in the oil storage device 27. The mixed gas enters the CO2 separation device 26, and the separated CO2 first passes through the second heat exchanger 22. After cooling, the low-temperature CO223 is injected into the oil-rich coal block 29 to form a freezing wall 4. The remaining pyrolysis gas is injected into the second semi-coke block 30 formed after the pyrolysis is completed, and the gasification reaction is started after ignition.

[0042] The combustion power generation device 18 supplies energy to the air separation device 14. The present invention continuously injects low-temperature N2 15 and low-temperature CO2 23 into the pyrolysis semi-coke block 28 and the oil-rich coal block 29, respectively, so that the temperature of the surrounding materials is reduced and a freezing wall 4 is formed, effectively preventing groundwater leakage during the in-situ reaction process.

[0043] like Figure 2As shown, the two injection wells and two output wells are arranged in a quadrilateral at four vertices. For example, in a group of pyrolysis semi-coke plots 28, the gasification injection well 5 and the gasification output well 6 are located at the vertices of one diagonal of the quadrilateral, and another group of gasification injection wells 5 and gasification output wells 6 are located at the vertices of another diagonal of the quadrilateral, and the temperature monitoring well 9 is located at the intersection of the two diagonals; similarly, in the oil-rich coal plot 29, a group of pyrolysis injection wells 7 and pyrolysis output wells 8 are located at the vertices of one diagonal of the quadrilateral, and another group of pyrolysis injection wells 7 and pyrolysis output wells 8 are located at the vertices of another diagonal of the quadrilateral, and the temperature monitoring well 9 is located at the intersection of the two diagonals. The injection wells and the output wells are located at the two ends of the diagonals, respectively, and the temperature monitoring well 9 is located at the intersection of the diagonals; the number of quadrilateral arrangements of the injection wells and the output wells is reasonably arranged according to the actual distribution of the coal seams, so as to reasonably utilize space resources.

[0044] The present invention comprehensively considers the slow oxidation part of the pyrolysis semi-coke, the pyrolysis part of the oil-rich coal, the joint operation of the two plots, the step-by-step utilization of the thermal energy of the pyrolysis products, and the preparation process of the freezing wall, and combines the unique well layout method to achieve the coupled operation of the slow oxidation of the semi-coke layer and the pyrolysis of the oil-rich coal layer, thereby making graded and quality-based utilization of the oil-rich coal resources.

[0045] On the other hand, the present invention provides a method for utilizing oil-rich coal in situ by pyrolysis and semi-coke gasification in a stratum by graded quality, comprising the following steps:

[0046] 1) The air separation device 14 separates the air 13 into low-temperature N2 and low-temperature O2. Part of the low-temperature O2 16 exchanges heat with the pyrolysis product through the first heat exchanger 20, and the preheated O2 21 enters the combustion power generation device 18 to participate in the combustion reaction. The remaining low-temperature O2 17 exchanges heat with the high-temperature CO2 separated by the CO2 separation device 26 through the second heat exchanger 22. The O2 24 after heat exchange enters the pyrolysis semi-coke block 28. The low-temperature N2 15 separated by the air separation device 14 is continuously injected into the vertical well of the pyrolysis semi-coke block 28;

[0047] 2) O2 24 enters the pyrolysis semi-coke plot 28 through the gasification injection well 5, and the gasification reaction of the semi-coke layer is started under the action of the ignition device 12 at the lower end of the gasification injection well 5. With the continuous injection and flow of O2 24, the gasification reaction area gradually moves toward the gasification output well 6 along the gasification horizontal well 10, and the gasification product flows out of the gasification output well 6 and enters the combustion power generation device 18 to undergo a combustion reaction. The high-temperature CO2 19 generated by the combustion carries a large amount of heat through the pyrolysis injection well 7 and enters the oil-rich coal plot 29, starting the in-situ pyrolysis reaction under the convection heating of the high-temperature fluid;

[0048] 3) The pyrolysis products are produced and flow out along the pyrolysis output well 8, passing through the first heat exchanger 20 and the gas-liquid separation device 25 in sequence, and the pyrolysis tar obtained by condensation separation is collected in the oil storage device 27. The mixed gas enters the CO2 separation device 26, and the separated CO2 first passes through the second heat exchanger 22, and is injected into the vertical well of the oil-rich coal block 29 after cooling to form a freezing wall 4. The remaining pyrolysis gas is injected into the second semi-coke block 30 formed after the pyrolysis is completed, and the gasification reaction is started after ignition.

[0049] The present invention uses an air separation device 14 to separate air 13 into low-temperature N2 and low-temperature O2. Part of the low-temperature O2 16 exchanges heat with the pyrolysis product through the first heat exchanger 20, and the remaining low-temperature O2 17 exchanges heat with the high-temperature CO2 through the second heat exchanger 22. The O2 24 after heat exchange enters the pyrolysis semi-coke block 28 through the gasification injection well 5, and the gasification reaction of the semi-coke layer is started under the action of the ignition device 12 at the lower end of the gasification injection well 5. With the continuous injection and flow of O2 24, the gasification reaction area gradually moves along the gasification horizontal well 10 to the gasification output well 6 side.

[0050] The gasification product flows out from the gasification output well 6 and enters the combustion power generation device 18. With the participation of preheated O2 21, a combustion reaction occurs. The high-temperature CO2 19 generated by the combustion carries a large amount of heat through the pyrolysis injection well 7 and enters the oil-rich coal plot 29, starting the in-situ pyrolysis reaction under the convection heating of the high-temperature fluid. The pyrolysis product is produced and flows out along the pyrolysis output well 8, passes through the first heat exchanger 20 to exchange heat with part of the low-temperature O2 after air separation, and then enters the gas-liquid separation device 25. The pyrolysis tar obtained by condensation separation is collected in the oil storage device 27. The mixed gas enters the CO2 separation device 26. The separated CO2 first passes through the second heat exchanger 22 to exchange heat with the remaining low-temperature O2. After cooling, it is injected into the oil-rich coal plot 29 to form a freezing wall 4. The remaining pyrolysis gas is injected into the second semi-coke plot 30 formed after the pyrolysis is completed, and the gasification reaction is started after ignition.

Claims

1. A stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal, characterized by: It comprises an air separation device (14), a first heat exchanger (20), a second heat exchanger (22), and a combustion power generation device (18); A pyrolysis injection well (7) and a pyrolysis output well (8) are excavated in the oil-rich coal plot (29). After the in-situ pyrolysis reaction is completed, the pyrolysis injection well (7) and the pyrolysis output well (8) are used as a gasification injection well (5) and a gasification output well (6), respectively. An ignition device (12) is provided at the bottom of the gasification injection well (5). An air separation device (14) is provided to separate the air (13) into low-temperature N2 and low-temperature O2. The oxygen output port of the air separation device (14) is connected to a first heat exchanger (20) and a second heat exchanger (22), respectively. The first heat exchanger (20) is used to preheat part of the oxygen and send it into the gasification injection well (5) to enter the pyrolysis semi-coke plot (28) to start the semi-coke layer gasification reaction under the action of the ignition device (12). The second heat exchanger (22) is used to preheat the remaining oxygen and send it into the combustion power generation device (18) to participate in the combustion reaction. The outlet of the gasification output well (6) is connected to the combustion power generation device (18), and the gasification product flows out of the gasification output well (6) and enters the combustion power generation device (18). The smoke outlet of the combustion power generation device (18) is connected to the inlet of the pyrolysis injection well (7). The high-temperature CO2 generated by the combustion power generation device (18) enters the oil-rich coal block (29) to start the in-situ pyrolysis reaction. The outlet of the pyrolysis output well (8) is connected to the hot gas input port of the first heat exchanger (20). The cold gas outlet of the first heat exchanger (20) is connected to the gas-liquid separation device (25). The liquid phase outlet of the gas-liquid separation device (25) is connected to the oil storage device (27). The gas phase outlet of the gas-liquid separation device (25) is connected to the CO2 separation device (26). The carbon dioxide output port of the CO2 separation device (26) is connected to the hot gas inlet of the second heat exchanger (22). The pyrolysis gas outlet of the CO2 separation device (26) is connected to the injection well of the second semi-coke block (30) formed after the pyrolysis is completed.

2. The stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal according to claim 1 is characterized by: In the pyrolysis semi-coke plot (28), a temperature monitoring well (9) is excavated between the gasification injection well (5) and the gasification output well (6); in the oil-rich coal plot (29), a temperature monitoring well (9) is excavated between the pyrolysis injection well (7) and the pyrolysis output well (8).

3. The stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal according to claim 2 is characterized by: A plurality of gasification horizontal wells (10) are excavated at different depths in the pyrolysis semi-coke plot (28), and the gasification injection well (5) and the gasification output well (6) are connected via the gasification horizontal wells (10).

4. The stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal according to claim 3 is characterized by: A plurality of pyrolysis horizontal wells (11) are excavated at different depths in the oil-rich coal block (29), and the pyrolysis injection well (7) and the pyrolysis output well (8) are connected via the pyrolysis horizontal wells (11).

5. The stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal according to claim 4 is characterized in that: A vertical well is excavated in the pyrolysis coke plot (28), the nitrogen outlet of the air separation device (14) is connected to the inlet of the vertical well, and low-temperature N2 is injected into the pyrolysis coke plot (28) to form a freezing wall (4).

6. The stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal according to claim 4 is characterized by: A vertical well is excavated in the oil-rich coal block (29), the cold gas outlet of the second heat exchanger (22) is connected to the inlet of the vertical well, and low-temperature CO2 is injected into the oil-rich coal block (29) to form a freezing wall (4).

7. The stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal according to claim 5 or 6, characterized in that: The combustion power generation device (18) supplies energy to the air separation device (14).

8. The stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal according to claim 7 is characterized by: In the pyrolysis semi-coke plot (28), a group of gasification injection wells (5) and gasification output wells (6) are located at the vertices of one diagonal line of a quadrilateral, another group of gasification injection wells (5) and gasification output wells (6) are located at the vertices of another diagonal line of the quadrilateral, and a temperature monitoring well (9) is located at the intersection of the two diagonals; In the oil-rich coal block (29), one group of pyrolysis injection wells (7) and pyrolysis output wells (8) are located at the vertices of one diagonal of a quadrilateral, another group of pyrolysis injection wells (7) and pyrolysis output wells (8) are located at the vertices of another diagonal of the quadrilateral, and a temperature monitoring well (9) is located at the intersection of the two diagonals.

9. A method for utilizing oil-rich coal in situ by pyrolysis and semi-coke gasification based on the system for utilizing oil-rich coal by grading and quality-differentiation according to claim 8, characterized in that The following steps are involved: 1) The air separation device (14) separates the air (13) into low-temperature N2 and low-temperature O2. Part of the low-temperature O2 passes through a first heat exchanger (20) to exchange heat with the pyrolysis product and then enters a combustion power generation device (18) to participate in the combustion reaction. The remaining low-temperature O2 passes through a second heat exchanger (22) to exchange heat with the high-temperature CO2 separated by the CO2 separation device (26) and then enters a pyrolysis semi-coke block (28). The low-temperature N2 separated by the air separation device (14) is continuously injected into a vertical well of the pyrolysis semi-coke block (28); 2) entering the pyrolysis semi-coke plot (28) through the gasification injection well (5) and starting the gasification reaction of the semi-coke layer under the action of the ignition device (12) at the lower end of the gasification injection well (5); the gasification product flows out from the gasification output well (6) and enters the combustion power generation device (18) to undergo a combustion reaction; the high-temperature CO2 generated by the combustion carries a large amount of heat through the pyrolysis injection well (7) and enters the oil-rich coal plot (29), starting the in-situ pyrolysis reaction under the convection heating of the high-temperature fluid; 3) The pyrolysis products are produced and flow out along the pyrolysis output well (8), and pass through the first heat exchanger (20) and the gas-liquid separation device (25) in sequence. The pyrolysis tar obtained by condensation separation is collected in the oil storage device (27), and the mixed gas enters the CO2 separation device (26). The separated CO2 first passes through the second heat exchanger (22), and is cooled and injected into the vertical well of the oil-rich coal block (29) to form a freezing wall (4). The remaining pyrolysis gas is injected into the second semi-coke block (30) formed after the pyrolysis is completed, and the gasification reaction is started after ignition.

10. The stratum classification and quality-based utilization system for in-situ pyrolysis and semi-coke gasification of oil-rich coal according to claim 8, characterized in that: The starting source of the in-situ pyrolysis reaction of the current oil-rich coal block (29) is the pyrolysis waste heat and gasification reaction heat of the previous coke block (28); After the oil-rich coal block (29) is pyrolyzed to form the second semi-coke block (30), the pyrolysis gas is injected into the semi-coke layer and ignited to initiate a gasification reaction.

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