A system and method for in-situ coal pyrolysis polygeneration and carbon dioxide sequestration

Abstract

The present invention belongs to the technical field of underground coal pyrolysis, and specifically relates to a multi-generation and carbon dioxide sequestration system and method for in-situ coal pyrolysis, including an in-situ coal pyrolysis module for initiating the pyrolysis of a coal seam and feeding the pyrolysis products into a product separation and processing module; a product separation and processing module for separating, processing, and utilizing the pyrolysis products and feeding the pyrolysis gas into a power generation module; a waste heat recovery and utilization module for generating power from the waste heat remaining in the underground coal seam after pyrolysis; a power generation module for generating power by relying on the pyrolysis gas separated by the product separation and processing module; and a carbon dioxide capture and sequestration module for capturing, processing, and sequestering the carbon dioxide generated in the power generation module and the product separation and processing module. The present invention obtains the carbon dioxide generated in the product separation and processing module and the power generation module through the carbon dioxide capture and sequestration module and sequesters it in the coal seam after pyrolysis, improving the safety of carbon dioxide sequestration and reducing the cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of underground coal pyrolysis, and particularly relates to a multi-generation and carbon dioxide sequestration system and method for in-situ coal pyrolysis. Background Art

[0002] The pattern of primary energy distribution of "rich in coal, poor in oil, and scarce in gas" determines the irreplaceable position of coal in China's energy consumption. In 2020, the proportion of coal in the total primary energy consumption was approximately 58.3%, with a year-on-year increase of 0.6%. Therefore, the dominant energy position of coal remains difficult to change before the goals of "carbon peak" and "carbon neutrality" are achieved. If the coal tar after coal pyrolysis can be fully utilized to produce products such as coal-based special fuels and chemical raw materials, it can effectively solve the problem of China's high dependence on foreign oil and gas resources.

[0003] Currently, the main coal pyrolysis technologies are all surface pyrolysis, that is, coal is mined and transported underground, and after washing and processing, it enters surface pyrolysis equipment to be converted into tar, gas, and semi-coke products. However, surface pyrolysis has problems such as large land occupation, overcapacity of pyrolysis semi-coke, air pollution, and water pollution. Compared with surface pyrolysis, in-situ underground coal pyrolysis has the advantages of small land occupation, less carbon emission footprint, and preventable ground subsidence. In addition, there is a large amount of heat remaining in the underground coal seam after in-situ coal pyrolysis. Reasonably using the residual heat of the pyrolyzed coal seam for power generation can effectively reduce the dependence on traditional fossil fuel power generation.

[0004] Currently, the following two methods are mainly used to reduce carbon emissions: one is to seek low-cost solutions to reduce carbon dioxide emissions; the other is carbon capture, utilization, and storage (CCUS).

[0005] Currently, the biggest challenge in the development of CCUS is the cost issue. Under high-intensity carbon emissions, the cost of carbon capture is relatively too high. Under the existing technical conditions, installing a carbon capture device will generate additional capital investment and operation and maintenance costs, etc. In addition, in the process of carbon sequestration, the transportation of carbon dioxide mainly uses tank trucks at present. The transportation volume of tank trucks is small and the transportation risk is high, while the pipeline network construction has high investment and poor flexibility. In addition, if leakage occurs during transportation, injection, and storage, it will affect the ecological environment and production activities near the accident. Therefore, a multi-generation and carbon dioxide sequestration system and method for in-situ coal pyrolysis are of great significance to energy development. Summary of the Invention

[0006] The purpose of the present invention is to provide a multi-generation and carbon dioxide sequestration system and method for in-situ coal pyrolysis to solve the technical problems of high cost and easy leakage of existing carbon dioxide sequestration methods.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] In a first aspect, a multi-generation system for in-situ coal pyrolysis and carbon dioxide sequestration includes an in-situ coal pyrolysis module, a product separation and processing module, a waste heat recovery and utilization module, a power generation module, and a carbon dioxide capture and sequestration module;

[0009] The in-situ coal pyrolysis module is used to fracture the underground coal seam, in-situ pyrolyze the underground coal seam through injecting high-temperature and high-pressure heat carriers and mild oxidation heating, and send the pyrolysis products to the product separation and processing module;

[0010] The product separation and processing module is used to separate, process and utilize the pyrolysis products, and send the pyrolysis gas in the pyrolysis products to the power generation module;

[0011] The waste heat recovery and utilization module is used to generate electricity by relying on the heat remaining in the underground coal seam after pyrolysis;

[0012] The power generation module is used to generate electricity by relying on the pyrolysis gas separated by the product separation and processing module;

[0013] The carbon dioxide capture and sequestration module is used to capture and process the carbon dioxide generated in the power generation module and the product separation and processing module, and transport the processed carbon dioxide to the in-situ coal pyrolysis module, and inject it into the pyrolyzed coal seam through the production well or the injection well for geological sequestration.

[0014] A further improvement of the present invention lies in that: the in-situ coal pyrolysis module includes a coal seam roof, a coal seam, a coal seam floor, a first injection well, a horizontal well, a second injection well, a production well, a mild oxidation heat supply zone, coal seam fissures, an internal component vortex heat exchange device, a sandstone layer, a pressurizing device, a heating device, an ignition device, and a heat exchanger;

[0015] The output port of the pressurizing device is connected to the first input port of the heating device, the output port of the heating device is respectively connected to the input ports of the first injection well and the second injection well, several horizontal wells are arranged between the outlet of the first injection well and the outlet of the second injection well, a production well is arranged at the center of the horizontal well, the output port of the production well is connected to the input port c of the first heat exchanger, the input port d of the first heat exchanger inputs a heat carrier, the output port a of the first heat exchanger is connected to the second input port of the heating device, the output port b of the first heat exchanger is connected to the product separation and processing module, the input port c of the first heat exchanger is connected to the output port b, the input port d of the first heat exchanger is connected to the output port a, the ignition device is respectively connected to the input ports of the first injection well and the second injection well, the first injection well, the second injection well, the production well and the horizontal well are arranged in the coal seam between the coal seam roof and the coal seam floor, there are several coal seam fissures and a mild oxidation heat supply zone in the coal seam, and an internal component vortex heat exchange device is arranged inside the horizontal well and at the bottom of the first injection well and the second injection well.

[0016] A further improvement of the present invention lies in that: the product separation and processing module includes a condensation separator, a dehydration tower, a heating furnace, a hydrofining reactor, a hot high-pressure separator, a hot low-pressure separator, a distillation column, a gas scrubber, an absorption tower, an electrostatic tar precipitator, and a first separator;

[0017] The output port b of the first heat exchanger is connected to the input port of the condensation separator, the first output port of the condensation separator is connected to the input port of the dehydration tower, and the coal tar is sent into the dehydration tower. The output port of the dehydration tower is connected to the first input port of the heating furnace, the output port of the heating furnace is connected to the first input port of the hydrofining reactor, the output port of the hydrofining reactor is connected to the input port of the hot high-pressure separator, the first output port of the hot high-pressure separator is connected to the input port of the hot low-pressure separator, and the second output port of the hot high-pressure separator is connected to the second input port of the hydrofining reactor to send the hydrogen generated in the hot high-pressure separator into the hydrofining reactor. The first output port of the hot low-pressure separator discharges the residual gas, and the second output port of the hot low-pressure separator is connected to the input port of the distillation column, and the distillation column outputs fuel oil and chemical raw materials;

[0018] The second output port of the condensation separator is connected to the input port of the gas scrubber to send the pyrolysis gas into the gas scrubber. The output port of the gas scrubber is connected to the input port of the absorption tower, the output port of the absorption tower is connected to the input port of the electrostatic tar precipitator, the first output port of the electrostatic tar precipitator is connected to the second input port of the heating furnace to send the tar in the electrostatic tar precipitator into the heating furnace, the second output port of the electrostatic tar precipitator is connected to the first separator, the first output port of the first separator is connected to the third input port of the hydrofining reactor to send the hydrogen in the first separator into the hydrofining reactor, and the second output port of the first separator is connected to the power generation module.

[0019] A further improvement of the present invention lies in that: the waste heat recovery and utilization module includes a first pressure pump, a second heat exchanger, a second separator, a steam turbine, a generator, a circulating water pump, a third injection well, and a production well;

[0020] The output port of the first pressure pump is respectively connected to the third injection well, the output port of the production well is connected to the input port of the second heat exchanger, the first output port of the second heat exchanger is connected to the input port of the second separator, and the second output port of the second heat exchanger is connected to the input port of the steam turbine to send the steam into the steam turbine. The first output port of the steam turbine is connected to the first input port of the circulating water pump, the second output port of the steam turbine is connected to the input port of the generator, and the output port of the second separator is connected to the second input port of the circulating water pump.

[0021] A further improvement of the present invention lies in that: the carbon dioxide sequestration module includes a booster pump, a heater, a second pressure pump, and a carbon dioxide concentration monitor;

[0022] The output port of the booster pump is connected to the input port of the heater, the output port of the heater is connected to the input port of the second pressure pump, and the output port of the second pressure pump is respectively connected to the first injection well, the second injection well and the production well;

[0023] The carbon dioxide concentration detector is arranged at the wellheads of the production well, the first injection well and the second injection well.

[0024] A further improvement of the present invention lies in that: an absorbent liquid is included in the carbon dioxide capture and storage module, and the absorbent liquid is an organic amine ionic liquid;

[0025] The organic amine ionic liquid includes an organic amine cation solution and an acid anion solution;

[0026] The organic amine cation solution is made by mixing one or more of diethanolamine, methyldiethanolamine, piperazine or diethylenetriamine with ethanolamine;

[0027] The acid anion solution is one of hexafluorophosphoric acid, tetrafluoroboric acid, sulfuric acid or acetic acid.

[0028] In a second aspect, a method for in-situ coal pyrolysis polygeneration and carbon dioxide storage includes the following steps:

[0029] S1. Fracture the coal seam through the first injection well and the second injection well to generate coal seam fissures and a mild oxidation heat supply zone in the coal seam, and inject a proppant into the coal seam fissures through the first injection well and the second injection well;

[0030] S2. Arrange an internal component vortex heat exchange device inside the horizontal well and at the bottoms of the first injection well and the second injection well; control the combustion of the mild oxidation heat supply zone through an ignition device to raise the temperature of the coal seam to be pyrolyzed;

[0031] S3. Generate a high-temperature and high-pressure heat carrier through a pressurizing device and a heating device, and inject it into the coal seam through the first injection well and the second injection well. Under the enhanced heat exchange effect of the internal component vortex heat exchange device and the proppant in the horizontal well, the coal starts to be pyrolyzed in-situ underground;

[0032] S4. Extract the pyrolysis products through the production well and send them into the product separation and processing module through the first heat exchanger. At the same time, the first heat exchanger sends the heat generated during the pyrolysis process into the heating device to generate high-temperature and high-pressure steam and inject it into the coal seam again;

[0033] S5. The pyrolysis products are preliminarily separated into coal tar products and pyrolysis gas products through a condensation separator; the coal tar products are dehydrated in a dehydration tower, then enter a heating furnace for heating, and subsequently enter a hydrofining reactor for hydroprocessing. The coal tar products leaving the hydrofining reactor first enter a hot high-pressure separator to separate hydrogen, which is sent back to the hydrofining reactor for reuse, then pass through a hot low-pressure separator to separate residual gas, and finally enter a distillation column to be separated into oil and gas products; the pyrolysis gas products are first subjected to gas washing and absorption treatment in a gas washing tower and an absorption tower, then enter an electrostatic tar precipitator to collect residual tar and send it to the heating furnace, and then the pyrolysis gas products are sent to a first separator to separate hydrogen and its waste heat pyrolysis gas. Among them, the hydrogen enters the tar hydrofining reactor, and the pyrolysis gas enters the power generation module for power generation;

[0034] S6. Use a first pressure pump to pump water into the pyrolyzed coal seam through a third injection well, heat it using the waste heat of the pyrolyzed coal seam, and extract the waste heat products from the production well and send them to a second heat exchanger. The second heat exchanger evaporates water into high-temperature steam relying on the heat in the waste heat products, and the high-temperature steam is passed into a steam turbine to drive a generator for power generation. The waste heat products in the second heat exchanger are passed into a second separator. The second separator separates the oil and gas products carried in the waste heat products and sends the water back to the circulating water pump for reuse;

[0035] S7. Send the carbon dioxide in the power generation module and the product separation and processing module to the carbon dioxide capture and storage module. The absorbent in the carbon dioxide capture and storage module absorbs carbon dioxide, and then is heated for desorption. The carbon dioxide gas is collected, and the absorbent is recycled after heating and desorption; the collected carbon dioxide gas is processed into a supercritical state through a booster pump and a heater, and is injected into the underground coal seam for geological storage through a second pressure pump from the first injection well, the second injection well or the production well.

[0036] A further improvement of the present invention lies in that: when injecting the high-temperature and high-pressure heat carrier in S2, first adopt slow heating, and when the whole coal seam reaches the preset temperature, increase the heating rate.

[0037] A further improvement of the present invention lies in that: when the temperature of the waste heat products is greater than or equal to 100 °C, the waste heat recovery and utilization module works normally, and when the temperature of the waste heat products is lower than 100 °C, the waste heat recovery and utilization module stops working.

[0038] A further improvement of the present invention lies in that: when the absorbent is heated for desorption after absorbing carbon dioxide, the absorbent after absorbing carbon dioxide is heated to 150 °C to complete desorption to obtain a pure absorbent.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] 1. The present invention obtains coal-based special fuels through in-situ coal pyrolysis, alleviating the problems of shortage of oil and gas resources in China and high dependence on foreign countries. In addition, by using the multi-generation technology to generate electricity with gas, the energy utilization efficiency is improved and the energy consumption is reduced, which is a powerful way to realize coal-based clean energy.

[0041] 2. The present invention combines a carbon dioxide capture and storage module to capture the carbon dioxide generated by the capture system and geologically store it through the pyrolyzed coal seam. The semi-coke structure and geological environment generated after pyrolysis provide natural conditions for carbon storage, improving the safety of carbon dioxide storage and reducing the storage cost, which is an effective means for treating carbon dioxide.

[0042] 3. The present invention uses the waste heat of the coal seam after in-situ pyrolysis to generate electricity, reducing the energy consumption of the system.

[0043] 4. The present invention controls the temperature and oxidation heating to control the combustion of part of the coal seam, and uses the heat released by coal combustion to promote the pyrolysis of the remaining coal seam, improving the efficiency of in-situ coal pyrolysis to achieve the purpose of shortening the construction period.

[0044] 5. The present invention uses an internal component vortex heat exchange device, which plays a role in strengthening heat exchange in the stage of injecting hot carrier for pyrolysis. On the other hand, in the stage of carbon dioxide storage, it acts as a static mixer to strengthen the absorption and storage of carbon dioxide.

[0045] 6. The present invention absorbs carbon dioxide in the process through amine-based ionic liquids, which can effectively reduce the carbon emissions of the system. And the amine-based ionic liquids can be desorbed by heating, enabling the absorbent to be recycled and reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0047] Figure 1 is the system block diagram of a multi-generation and carbon dioxide storage system for in-situ coal pyrolysis according to the present invention;

[0048] Figure 2 is the schematic structural diagram of the in-situ coal pyrolysis module of a multi-generation and carbon dioxide storage system for in-situ coal pyrolysis according to the present invention;

[0049] Figure 3 is the schematic structural diagram of the product separation and processing module of a multi-generation and carbon dioxide storage system for in-situ coal pyrolysis according to the present invention;

[0050] Figure 4 is the schematic structural diagram of the waste heat recovery and utilization module of a multi-generation and carbon dioxide storage system for in-situ coal pyrolysis according to the present invention;

[0051] Figure 5 This is a schematic structural diagram of the carbon dioxide sequestration module of a multi-generation system for in-situ coal pyrolysis and carbon dioxide sequestration according to the present invention;

[0052] Figure 6 This is a schematic diagram of the well layout connection method with a sandstone layer in a multi-generation system for in-situ coal pyrolysis and carbon dioxide sequestration according to the present invention.

[0053] In the figure, 1 is the coal seam roof; 2 is the coal seam; 3 is the coal seam floor; 4 is the first injection well; 5 is the horizontal well; 6 is the second injection well; 7 is the production well; 8 is the mild oxidation heat supply belt; 9 is the coal seam fracture; 10 is the internal component vortex heat exchange device; 11 is the sandstone layer; 12 is the pressurizing device; 13 is the heating device; 14 is the ignition device; 15 is the first heat exchanger; 16 is the second coal seam; 17 is the third coal seam; 18 is the second sandstone layer; 20 is the product separation and processing module; 21 is the condensation separator; 22 is the dehydration tower; 23 is the heating furnace; 24 is the hydrofining reactor; 25 is the hot high-pressure separator; 26 is the hot low-pressure separator; 27 is the rectification tower; 28 is the scrubbing tower; 29 is the absorption tower; 30 is the electrocatalytic tar precipitator; 31 is the first separator; 50 is the power generation module; 41 is the first pressure pump; 42 is the second heat exchanger; 43 is the second separator; 44 is the circulating water pump; 45 is the steam turbine; 46 is the generator; 47 is the third injection well; 48 is the production well; 50 is the power generation module; 51 is the booster pump; 52 is the heater; 53 is the second pressure pump; 54 is the carbon dioxide concentration detector. Specific embodiments

[0054] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0055] The following detailed descriptions are all exemplary descriptions, aiming to provide further detailed descriptions of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0056] Embodiment 1

[0057] As Figure 1 shown, a multi-generation system for in-situ coal pyrolysis and carbon dioxide sequestration includes an in-situ coal pyrolysis module, a product separation and processing module 20, a waste heat recovery and utilization module, a power generation module 50, and a carbon dioxide capture and sequestration module;

[0058] In-situ coal pyrolysis module, used for the production part, for fracturing underground coal seams. By injecting high-temperature and high-pressure heat carriers and mild oxidation for heat supply, the underground coal seams are pyrolyzed in-situ. The pyrolysis volatiles generated by coal pyrolysis are extracted to the ground through catalytic regulation and upgrading in the production well and then introduced into the product separation and processing module 20;

[0059] Product separation and processing module 20, used for separating, processing and utilizing oil and gas products. The oil and gas products are condensed and separated, the tar products are purified and processed for the second time. After the gas products are separated, part of them are recycled and reused, and the other part is introduced into the power generation module;

[0060] Waste heat recovery and utilization module, used for utilizing a large amount of waste heat from the underground coal seams after pyrolysis, generating electricity through waste heat and supplying the system energy consumption;

[0061] Power generation module 50, used for generating electricity by relying on the gas separated by the product separation and processing module 20 to supply the energy consumption of the whole system;

[0062] Carbon dioxide capture and storage module, including carbon dioxide capture, carbon dioxide processing, pipeline transportation and carbon dioxide storage process flows. It is used for capturing the carbon dioxide generated in the power generation module 50, processing it and then transporting it through pipelines to the in-situ coal pyrolysis module, and injecting it into the pyrolyzed coal seams through production wells or injection wells for geological storage.

[0063] As Figure 2 shown, the in-situ coal pyrolysis module includes coal seam roof 1, coal seam 2, coal seam floor 3, first injection well 4, horizontal well 5, second injection well 6, production well 7, mild oxidation heat supply belt 8, coal seam fissure 9, internal component vortex heat exchange device 10, sandstone layer 11, pressurizing device 12, heating device 13, ignition device 14 and heat exchanger 15;

[0064] The outlet of the pressurizing device 12 is connected to the first inlet of the heating device 13. The outlet of the heating device 13 is respectively connected to the inlets of the first injection well 4 and the second injection well 6. A horizontal well 5 is provided between the outlets of the first injection well 4 and the second injection well 6. A production well 7 is provided at the center of the horizontal well 5. The outlet of the production well 7 is connected to the inlet c of the first heat exchanger 15. The inlet d of the first heat exchanger 15 inputs a heat carrier, and the heat carrier is water, nitrogen, air, etc. The outlet a of the heat exchanger is connected to the second inlet of the heating device 13. The outlet b of the first heat exchanger 15 is connected to the product separation and processing module 20. The inlet c of the first heat exchanger is connected to the outlet b, and the inlet d of the first heat exchanger is connected to the outlet a. The ignition device 14 is respectively connected to the inlets of the first injection well 4 and the second injection well 6. The first injection well 4, the second injection well 6, the production well 7 and the horizontal well 5 are arranged in the coal seam between the coal seam roof 1 and the coal seam floor 3. There are several coal seam fissures 9 and a mild oxidation heat supply zone 8 in the coal seam 2. An internal component vortex heat exchange device 10 is provided inside the horizontal well 5 and at the bottoms of the first injection well 4 and the second injection well 6;

[0065] A heat preservation casing device is provided on the production well 7, which can ensure that the internal temperature of the production well is higher than 360 °C, preventing the pyrolysis products from condensing and adhering to the pipe wall during the product extraction process, causing blockage.

[0066] The internal component vortex heat exchange device 10 is arranged in the first injection well 4, the second injection well 6 and the horizontal well 5. It can strengthen the heat exchange of the heat carrier during the stage of injecting the heat carrier; it acts as a static mixer during the carbon dioxide sequestration stage, strengthening the absorption and sequestration of carbon dioxide.

[0067] The energy consumption required by the heating device 13 is provided by clean energy such as solar energy and wind energy.

[0068] As Figure 3 shown, the product separation and processing module 20 includes a condensation separator 21, a dehydration tower 22, a heating furnace 23, a hydrofining reactor 24, a hot high-pressure separator 25, a hot low-pressure separator 26, a rectification tower 27, a scrubbing tower 28, an absorption tower 29, an electric tar precipitator 30 and a first separator 31;

[0069] The outlet b of the first heat exchanger 15 is connected to the inlet of the condensation separator 21. The first outlet of the condensation separator 21 is connected to the inlet of the dehydration tower 22, and the coal tar is sent into the dehydration tower 22. The outlet of the dehydration tower 22 is connected to the first inlet of the heating furnace 23. The outlet of the heating furnace 23 is connected to the first inlet of the hydrofining reactor 24. The outlet of the hydrofining reactor 24 is connected to the inlet of the hot high-pressure separator 25. The first outlet of the hot high-pressure separator 25 is connected to the inlet of the hot low-pressure separator 26. The second outlet of the hot high-pressure separator 25 is connected to the second inlet of the hydrofining reactor 24, and the hydrogen generated in the hot high-pressure separator 25 is sent into the hydrofining reactor 24. The first outlet of the hot low-pressure separator 26 discharges the residual gas. The second outlet of the hot low-pressure separator 26 is connected to the inlet of the rectification tower 27, and the rectification tower 27 outputs fuel oil and chemical raw materials;

[0070] The second outlet of the condensation separator 21 is connected to the inlet of the scrubbing tower, and the pyrolysis gas is sent into the scrubbing tower 28. The outlet of the scrubbing tower 28 is connected to the inlet of the absorption tower 29. The outlet of the absorption tower 29 is connected to the inlet of the electro-tar precipitator 30. The first outlet of the electro-tar precipitator 30 is connected to the second inlet of the heating furnace 23, and the tar in the electro-tar precipitator 30 is sent into the heating furnace 23. The second outlet of the electro-tar precipitator 30 is connected to the first separator 31. The first outlet of the first separator 31 is connected to the third inlet of the hydrofining reactor 24, and the hydrogen in the first separator 31 is sent into the hydrofining reactor 24. The second outlet of the first separator 31 is connected to the power generation module 50, and the pyrolysis gas is sent into the power generation module 50 for power generation;

[0071] As Figure 4 shown, the waste heat recovery and utilization module includes a first pressure pump 41, a second heat exchanger 42, a second separator 43, a steam turbine 45, a generator 46 and a circulating water pump 44;

[0072] The outlet of the first pressure pump 41 is connected to the third injection well 47. The outlet of the production well 48 is connected to the inlet of the second heat exchanger 42. The first outlet of the second heat exchanger 42 is connected to the inlet of the second separator 43. The second outlet of the second heat exchanger 42 is connected to the inlet of the steam turbine 45, and the secondary steam is sent into the steam turbine 45. The first outlet of the steam turbine 45 is connected to the first inlet of the circulating water pump 44. The second outlet of the steam turbine 45 is connected to the inlet of the generator 46. The outlet of the second separator 43 is connected to the second inlet of the circulating water pump 44.

[0073] The power generation module includes a gas turbine and a steam turbine.

[0074] As Figure 5 shown, the carbon dioxide sequestration module includes a booster pump 51, a heater 52, a second pressure pump 53, and a carbon dioxide concentration detector 54;

[0075] The outlet of the booster pump 51 is connected to the inlet of the heater 52. The outlet of the heater 52 is connected to the inlet of the second pressure pump 53. The outlet of the second pressure pump 53 is connected to the injection well. The carbon dioxide concentration detector 54 is arranged at each wellhead.

[0076] Embodiment 2

[0077] A method for in-situ coal pyrolysis polygeneration and carbon dioxide sequestration includes the following steps:

[0078] S1. Fracture the coal seam 2 through the first injection well 4 and the second injection well 6 to generate coal seam fractures 9 and a mild oxidation heat supply zone 8 in the coal seam 2, and inject proppants into the coal seam fractures 9 through the first injection well 4 and the second injection well 6;

[0079] S2. Arrange the internal component vortex heat exchange device 10 inside the horizontal well 5 and at the bottoms of the first injection well 4 and the second injection well 6; control the combustion of the mild oxidation heat supply zone through the ignition device 14 to raise the temperature of the coal seam to be pyrolyzed;

[0080] S3. Generate high-temperature and high-pressure heat carriers through the pressurizing device 12 and the heating device 13, and inject them into the coal seam 2 through the first injection well 4 and the second injection well 6. Under the enhanced heat exchange effect of the internal component vortex heat exchange device 10 and the proppants in the horizontal well 5, the coal starts in-situ pyrolysis underground;

[0081] S4. Extract the pyrolysis products through the production well 7 and send them into the product separation and processing module 20 through the first heat exchanger 15. At the same time, the first heat exchanger 15 sends the heat generated during the pyrolysis process into the heating device 13 to generate high-temperature and high-pressure steam and inject it into the coal seam 2 again;

[0082] S5. The pyrolysis products are preliminarily separated into coal tar products and pyrolysis gas products through the condensation separator 21; the coal tar products are dehydrated in the dehydration tower 22, then enter the heating furnace 23 for heating, and then enter the hydrofining reactor 24 for hydrocracking reaction. The coal tar products leaving the hydrofining reactor 24 first enter the hot high-pressure separator 25 to separate hydrogen and send it back to the hydrofining reactor 24 for reuse, then separate the residual gas through the hot low-pressure separator 26, and finally enter the distillation column 27 to be separated into oil and gas products; the pyrolysis gas products are first subjected to gas washing and absorption treatment in the gas washing tower 28 and the absorption tower 29, then enter the electric tar precipitator 30 to collect the residual tar and send it to the heating furnace 23, and then the pyrolysis gas products are sent into the first separator 31 to separate hydrogen and its waste heat pyrolysis gas. Among them, the hydrogen enters the tar hydrofining reactor 24, and the pyrolysis gas enters the power generation module 50 for power generation;

[0083] S6. Use the first pressure pump 41 to pump water into the pyrolyzed coal seam 2 through the third injection well 47, heat it using the waste heat of the pyrolyzed coal seam, extract the waste heat product from the production well 48 and send it to the second heat exchanger 42. The second heat exchanger 42 evaporates water into high-temperature steam by relying on the heat in the waste heat product, and passes the high-temperature steam into the steam turbine 45 to drive the generator 46 to generate electricity. The waste heat product in the second heat exchanger 42 is passed into the second separator 43. The second separator 43 separates the oil and gas products carried in the waste heat product and passes the water back to the circulating water pump 44 for reuse;

[0084] S7. Send the carbon dioxide in the power generation module 50 and the product separation and processing module 20 to the carbon dioxide capture and storage module. The absorbent in the carbon dioxide capture and storage module absorbs carbon dioxide, and then is heated for desorption. The carbon dioxide gas is collected, and the absorbent is recycled after heating and desorption; Process the collected carbon dioxide gas into a supercritical state through the booster pump 51 and the heater 52, and inject the supercritical carbon dioxide into the underground coal seam 2 for geological storage from the first injection well 4, the second injection well 6 or the production well 7 through the second pressure pump 53.

[0085] Manufacturing method of proppant: Grind the carrier material and red mud together, and then carry out homogenization and refinement treatment to obtain a mixed powder. The particle size range of the mixed powder is 0.4 - 2.0 mm; Mix the mixed powder with the binder evenly and then send it into a granulator for granulation to obtain pellets; Dry the pellets and then calcine them at 1000 - 1200 °C to obtain the proppant for in-situ underground coal pyrolysis.

[0086] In the said mixed material, the carrier material accounts for 35% - 60 wt.% of the mass of the mixed powder; the red mud accounts for 40% - 65 wt.% of the mass of the mixed powder. The carrier material is one or more of ceramsite, metal aluminum balls, resin-coated sand, and the binder is one or more of phenolic resin, polyurethane, and sodium silicate.

[0087] Preparation method of organic amine ionic liquid: Weigh equimolar amounts of organic amine and acid respectively, place them in ice water and stir to dissolve. After stirring evenly, slowly add the acid solution to the organic amine solution, then stir evenly and react. Continue to carry out rotary evaporation at 80 °C - 100 °C, and finally dry at 60 °C - 80 °C for 24 hours.

[0088] The said organic amine solution is prepared by mixing ethanolamine (MEA) with one or more of diethanolamine (DEA), methyldiethanolamine (MDEA), piperazine (PZ), and diethylenetriamine (DETA); the said acid solution is one of hexafluorophosphoric acid, tetrafluoroboric acid, sulfuric acid, and acetic acid.

[0089] When injecting high-temperature and high-pressure heat carriers into the first injection well 4 and the second injection well 6, first raise the temperature slowly. When the temperature of the coal seam 2 reaches 200 °C, start to rapidly raise the temperature for heating to increase the initial pyrolysis rate of the coal seam and the pyrolysis tar yield.

[0090] The waste heat recovery and utilization module uses a large amount of waste heat generated after in-situ coal pyrolysis to generate electricity, effectively utilizing energy.

[0091] The waste heat recovery and utilization module uses the waste heat of the pyrolyzed coal seam to heat steam. It can be used normally when the temperature of the waste heat product is greater than 100 °C, and stops using when the temperature is lower than 100 °C.

[0092] Use organic amine ionic liquid as the absorbent to absorb carbon dioxide in the power generation module 50 and the product separation and processing module;

[0093] When the absorbed mixed solution is heated to 150 °C, carbon dioxide can be desorbed, and the obtained organic amine ionic liquid absorbent can be reused.

[0094] Utilize the coal seam after underground pyrolysis for geological sequestration of supercritical carbon dioxide. The coal seam after pyrolysis provides natural conditions for carbon dioxide sequestration.

[0095] Utilize the injection wells and production wells in the in-situ coal pyrolysis module to inject supercritical carbon dioxide, reducing the construction cost.

[0096] Through the injection of carbon dioxide, drive out the residual pyrolysis gas adsorbed in coal rock and semicoke, further recover the pyrolysis gas, and improve the recovery rate.

[0097] Utilize the waste heat of the geological environment after underground coal pyrolysis to stabilize the state of supercritical carbon dioxide and reduce the risk of carbon dioxide leakage.

[0098] Example 3

[0099] As Figure 6As shown in the figure, a well layout method for an in-situ coal pyrolysis poly-generation and carbon dioxide sequestration system includes a coal seam roof 1, a coal seam 2, a sandstone layer 11, a second coal seam 16, a second sandstone layer 18, a third coal seam 17, a first injection well 4, a second injection well 6, a horizontal well 5, a production well 7, a coal seam floor 3, a mild oxidation heat supply zone 8, and an internal component vortex heat exchange device 10. Below the coal seam roof 1 is the coal seam 2, below the coal seam 2 is the sandstone layer 11, below the sandstone layer 11 is the second coal seam 16, below the second coal seam 16 is the second sandstone layer 18, below the second sandstone layer 18 is the third coal seam 17, and below the third coal seam 17 is the coal seam floor 3. The first injection well 4, the second injection well 6, and the production well 7 successively pass through the coal seam roof 1, the coal seam 2, the sandstone layer 11, the second coal seam 16, the second sandstone layer 18, the third coal seam 17, the coal seam 2, and there is a horizontal well 5 in the third coal seam 17. There is a mild oxidation heat supply zone 8 in the second coal seam 16, and there are fissures in the sandstone layer 11 and the second sandstone layer 18.

[0100] The mild oxidation heat supply zone 8 is used to burn part of the underground coal seam, control the heat generated by coal combustion, strengthen the pyrolysis of the remaining coal seams, reduce the energy consumption of pyrolysis, and improve the pyrolysis efficiency.

[0101] For thick massive coal seams and thick massive sandstone layers underground, control the combustion of the middle part of the coal seam to heat the remaining part of the coal seam; for multi-coal seams and thin massive sandstone layers, control the combustion of the middle coal seam to strengthen the pyrolysis efficiency of the upper and lower coal seams.

[0102] As is known by technical common sense, the present invention can be implemented by other embodiments that do not depart from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all aspects and are not the only ones. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent substitutions, and any modification or equivalent substitution that does not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A multi-generation system for in-situ coal pyrolysis and carbon dioxide sequestration, characterized in that, it includes an in-situ coal pyrolysis module, a product separation and processing module (20), a waste heat recovery and utilization module, a power generation module (50) and a carbon dioxide capture and sequestration module; The in-situ coal pyrolysis module is used to fracture the underground coal seam, in-situ pyrolyze the underground coal seam through injecting high-temperature and high-pressure heat carriers and mild oxidation heating, and send the pyrolysis products to the product separation and processing module (20); The product separation and processing module (20) is used to separate, process and utilize the pyrolysis products, and send the pyrolysis gas in the pyrolysis products to the power generation module (50); The waste heat recovery and utilization module is used to generate electricity by relying on the heat remaining in the underground coal seam after pyrolysis; The power generation module (50) is used to generate electricity by relying on the pyrolysis gas separated by the product separation and processing module (20); The carbon dioxide capture and sequestration module is used to capture and process the carbon dioxide generated in the power generation module (50) and the product separation and processing module (20), and transport the processed carbon dioxide to the in-situ coal pyrolysis module, and inject it into the pyrolyzed coal seam through a production well or an injection well for geological sequestration; The in-situ coal pyrolysis module includes a coal seam roof (1), a coal seam (2), a coal seam floor (3), a first injection well (4), a horizontal well (5), a second injection well (6), a production well (7), a mild oxidation heat supply belt (8), coal seam fissures (9), an internal component vortex heat exchange device (10), a sandstone layer (11), a pressurization device (12), a heating device (13), an ignition device (14) and a first heat exchanger (15); The output port of the pressurization device (12) is connected to the first input port of the heating device (13), the output port of the heating device (13) is respectively connected to the input ports of the first injection well (4) and the second injection well (6), several horizontal wells (5) are arranged between the outlets of the first injection well (4) and the second injection well (6), a production well (7) is arranged at the center of the horizontal well (5), the output port of the production well (7) is connected to the input port c of the first heat exchanger (15), the input port d of the first heat exchanger (15) inputs heat carriers, the output port a of the first heat exchanger is connected to the second input port of the heating device (13), the output port b of the first heat exchanger (15) is connected to the product separation and processing module (20), the input port c of the first heat exchanger is connected to the output port b, the input port d of the first heat exchanger is connected to the output port a, the ignition device (14) is respectively connected to the input ports of the first injection well (4) and the second injection well (6), the first injection well (4), the second injection well (6), the production well (7) and the horizontal well (5) are arranged in the coal seam between the coal seam roof (1) and the coal seam floor (3), there are several coal seam fissures (9) and mild oxidation heat supply belts (8) in the coal seam (2), and an internal component vortex heat exchange device (10) is arranged inside the horizontal well (5) and at the bottom of the first injection well (4) and the second injection well (6); The waste heat recovery and utilization module includes a first pressure pump (41), a second heat exchanger (42), a second separator (43), a steam turbine (45), a generator (46), a circulating water pump (44), a third injection well (47), and a production well (48); The output port of the first pressure pump (41) is connected to the third injection well (47), the output port of the production well (48) is connected to the input port of the second heat exchanger (42), the first output port of the second heat exchanger (42) is connected to the input port of the second separator (43), the second output port of the second heat exchanger (42) is connected to the input port of the steam turbine (45) to send steam into the steam turbine (45), the first output port of the steam turbine (45) is connected to the first input port of the circulating water pump (44), the second output port of the steam turbine (45) is connected to the input port of the generator (46), and the output port of the second separator (43) is connected to the second input port of the circulating water pump (44); The carbon dioxide sequestration module includes a booster pump (51), a heater (52), a second pressure pump (53), and a carbon dioxide concentration detector (54); The output port of the booster pump (51) is connected to the input port of the heater (52), the output port of the heater (52) is connected to the input port of the second pressure pump (53), and the output port of the second pressure pump (53) is respectively connected to the first injection well (4), the second injection well (6), and the production well (7); The carbon dioxide concentration detector (54) is arranged at the wellheads of the production well (7), the first injection well (4), and the second injection well (6); The carbon dioxide in the power generation module (50) and the product separation and processing module (20) is sent into the carbon dioxide capture and sequestration module. The absorbent in the carbon dioxide capture and sequestration module absorbs carbon dioxide, and then is heated for desorption. The carbon dioxide gas is collected, and the absorbent is recycled after heating and desorption; the collected carbon dioxide gas is processed into a supercritical state by the booster pump (51) and the heater (52), and the supercritical carbon dioxide is injected into the underground coal seam (2) for geological sequestration from the first injection well (4), the second injection well (6), or the production well (7) through the second pressure pump (53).

2. A coal in-situ pyrolysis polygeneration and carbon dioxide sequestration system according to claim 1, characterized in that the product separation and processing module (20) includes a condensation separator (21), a dehydration tower (22), a heating furnace (23), a hydrofining reactor (24), a hot high-pressure separator (25), a hot low-pressure separator (26), a rectifying column (27), a scrubbing tower (28), an absorption tower (29), an electrostatic tar precipitator (30), and a first separator (31); The outlet b of the first heat exchanger (15) is connected to the inlet of the condensation separator (21). The first outlet of the condensation separator (21) is connected to the inlet of the dehydration tower (22), and the coal tar is sent into the dehydration tower (22). The outlet of the dehydration tower (22) is connected to the first inlet of the heating furnace (23). The outlet of the heating furnace (23) is connected to the first inlet of the hydrofining reactor (24). The outlet of the hydrofining reactor (24) is connected to the inlet of the hot high-pressure separator (25). The first outlet of the hot high-pressure separator (25) is connected to the inlet of the hot low-pressure separator (26). The second outlet of the hot high-pressure separator (25) is connected to the second inlet of the hydrofining reactor (24), and the hydrogen generated in the hot high-pressure separator (25) is sent into the hydrofining reactor (24). The first outlet of the hot low-pressure separator (26) discharges the residual gas. The second outlet of the hot low-pressure separator (26) is connected to the inlet of the rectification tower (27), and the rectification tower (27) outputs fuel oil and chemical raw materials; The second outlet of the condensation separator (21) is connected to the inlet of the scrubbing tower (28), and the pyrolysis gas is sent into the scrubbing tower (28). The outlet of the scrubbing tower (28) is connected to the inlet of the absorption tower (29). The outlet of the absorption tower (29) is connected to the inlet of the electrostatic tar precipitator (30). The first outlet of the electrostatic tar precipitator (30) is connected to the second inlet of the heating furnace (23), and the tar in the electrostatic tar precipitator (30) is sent into the heating furnace (23). The second outlet of the electrostatic tar precipitator (30) is connected to the first separator (31). The first outlet of the first separator (31) is connected to the third inlet of the hydrofining reactor (24), and the hydrogen in the first separator (31) is sent into the hydrofining reactor (24). The second outlet of the first separator (31) is connected to the power generation module (50).

3. A coal in-situ pyrolysis polygeneration and carbon dioxide sequestration system according to claim 1, characterized in that, an absorbent liquid is included in the carbon dioxide capture and sequestration module, and the absorbent liquid is an organic amine-based ionic liquid; the organic amine-based ionic liquid includes an organic amine cation solution and an acid anion solution; the organic amine cation solution is made by mixing one or more of diethanolamine, methyldiethanolamine, piperazine or diethylenetriamine with ethanolamine; the acid anion solution is one of hexafluorophosphoric acid, tetrafluoroboric acid, sulfuric acid or acetic acid.

4. A coal in-situ pyrolysis polygeneration and carbon dioxide sequestration method, characterized in that, this method is carried out by using the coal in-situ pyrolysis polygeneration and carbon dioxide sequestration system described in any one of claims 1-3, and the method includes the following steps: S1. Fracture the coal seam (2) through the first injection well (4) and the second injection well (6) to generate coal seam fissures (9) and a mild oxidation heat supply zone (8) in the coal seam (2), and inject a proppant into the coal seam fissures (9) through the first injection well (4) and the second injection well (6); S2. Arrange the internal component vortex heat exchange device (10) at the bottom inside the horizontal well (5), the first injection well (4), and the second injection well (6); control the combustion of the mild oxidation heat supply zone through the ignition device (14) to raise the temperature of the coal seam to be pyrolyzed. S3. Generate high-temperature and high-pressure heat carriers through the pressurizing device (12) and the heating device (13), and inject them into the coal seam (2) through the first injection well (4) and the second injection well (6). Under the action of the internal component vortex heat exchange device (10) and the proppant enhanced heat exchange in the horizontal well (5), the coal starts in-situ pyrolysis underground. S4. Extract the pyrolysis products through the production well (7) and send them into the product separation and processing module (20) through the first heat exchanger (15). At the same time, the first heat exchanger (15) sends the heat generated during the pyrolysis process into the heating device (13) to generate high-temperature and high-pressure steam and inject it into the coal seam (2) again. S5. The pyrolysis products are preliminarily separated into coal tar products and pyrolysis gas products through the condensation separator (21); the coal tar products are dehydrated in the dehydration tower (22), then enter the heating furnace (23) for heating, and then enter the hydrofining reactor (24) for hydrofining reaction. The coal tar products leaving the hydrofining reactor (24) first enter the hot high-pressure separator (25) to separate hydrogen and send it back to the hydrofining reactor (24) for reuse, then pass through the hot low-pressure separator (26) to separate the residual gas, and finally enter the distillation column (27) to be separated into oil and gas products; the pyrolysis gas products are first washed and absorbed in the scrubbing tower (28) and the absorption tower (29), then enter the electrostatic tar precipitator (30) to collect the residual tar and send it to the heating furnace (23), and then the pyrolysis gas products are sent into the first separator (31) to separate hydrogen and its residual pyrolysis gas. Among them, the hydrogen enters the tar hydrofining reactor (24), and the pyrolysis gas enters the power generation module (50) for power generation. S6. Use the first pressure pump (41) to pump water into the pyrolyzed coal seam (2) through the third injection well (47), heat it using the residual heat of the pyrolyzed coal seam, and extract the residual heat products from the production well (48) and send them into the second heat exchanger (42). The second heat exchanger (42) evaporates the water into high-temperature steam by relying on the heat in the residual heat products, and passes the high-temperature steam into the steam turbine (45) to drive the generator (46) for power generation. The residual heat products in the second heat exchanger (42) are passed into the second separator (43), and the second separator (43) separates the oil and gas products carried in the residual heat products and passes the water into the circulating water pump (44) for reuse. S7. Send the carbon dioxide in the power generation module (50) and the product separation and processing module (20) into the carbon dioxide capture and storage module. The absorbent in the carbon dioxide capture and storage module absorbs carbon dioxide, and then is heated and desorbed. The carbon dioxide gas is collected, and the absorbent is recycled after heating and desorption; the collected carbon dioxide gas is processed into a supercritical state through the booster pump (51) and the heater (52), and is injected into the underground coal seam (2) for geological storage through the second pressure pump (53) from the first injection well (4), the second injection well (6), or the production well (7).

5. A method for in-situ coal pyrolysis polygeneration and carbon dioxide sequestration according to claim 4, characterized in that, when injecting the high-temperature and high-pressure heat carrier in S2, slow heating is first adopted, and when the whole coal seam (2) reaches the preset temperature, the heating rate is increased.

6. A method for in-situ coal pyrolysis polygeneration and carbon dioxide sequestration according to claim 4, characterized in that, when the temperature of the waste heat product is greater than or equal to 100 °C, the waste heat recovery and utilization module works normally, and when the temperature of the waste heat product is lower than 100 °C, the waste heat recovery and utilization module stops working.

7. An in-situ coal pyrolysis polygeneration and carbon dioxide sequestration system according to claim 4, characterized in that, when the absorbent solution is heated for desorption after absorbing carbon dioxide, the absorbent solution after absorbing carbon dioxide is heated to 150 °C to complete desorption to obtain a pure absorbent solution.

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