IGFC system containing oxygen storage device and pressure swing adsorption device and method

Abstract

The invention discloses an IGFC system containing an oxygen storage device and a pressure swing adsorption device and a method. The system comprises an air separation device, an oxygen storage tank, a gasification furnace, a waste heat boiler, a fly ash treatment device, a desulfurization device, a pressure swing adsorption device, an air compression and turbine device, an expansion machine, a heating device, a solid oxide fuel cell, an oxygen-enriched combustion chamber, a waste gas turbine device, a steam turbine, a waste heat boiler, a methane synthesis device and a water supply device. A heat exchanger and a fuel gas heat supply device; according to the system, new energy which cannot be consumed in time is converted into O2 by using an oxygen storage device, and the O2 is stored and supplied to internal elements of the IGFC system; meanwhile, H2 in the purified gas of the IGFC system is separated by using the pressure swing adsorption device, and the separated H2 and high-concentration CO2 generated by the oxygen-enriched combustion chamber of the IGFC system are used for generating methane supply gas load in the methane synthesis device, so that the overall energy utilization rate of the system is improved, and the carbon capture, compression and transportation cost in the carbon treatment process is reduced.

Description

Technical Field

[0001] The present invention relates to the fields of energy-saving and environmental protection industry technology and new energy technology, and specifically to an IGFC power generation technology containing an oxygen storage device and a pressure swing adsorption device that improves the overall net output power of an IGFC system and reduces the cost of CO2 compression, transportation and storage of the IGFC system. Background Art

[0002] In the process of achieving the "dual carbon" goal, the low-carbon transformation of the energy structure has accelerated. Since the beginning of this century, the global energy structure has been adjusted at an accelerated pace, the technical level and economic efficiency of new energy have been greatly improved, the utilization of wind energy and solar energy has achieved leapfrog development, and the scale has increased by several times. In the past five years, renewable energy has provided 60% of the world's new power generation, and the proportion of new energy in the power generation field is gradually increasing. In the face of the integrated energy system with high wind and solar penetration in the future, thermal power still plays a supporting and bottoming role. The integrated gasification fuel cell system (IGFC) is a new, green and efficient coal-based power generation technology that realizes efficient production of electricity by organically integrating coal gasification and fuel cells. Compared with traditional thermal power, this technology uses fuel cells to directly convert the chemical energy in coal gasification gas into electrical energy. In addition, IGFC can achieve carbon enrichment during the power generation process, creating favorable conditions for direct capture.

[0003] The patent document with application publication number CN109350988A discloses an IGFC power generation system and method that couples the CO2 liquefaction process with cryogenic air separation. The system couples the CO2 liquefaction process with cryogenic air separation, so that the IGFC power generation system eliminates the refrigeration equipment required for the CO2 liquefaction process, simplifies the process, reduces equipment investment and operating costs; at the same time, it achieves optimal utilization of energy and can improve the power generation efficiency of the IGFC system. The patent document with application publication number CN113644280A discloses an IGFC system and method that uses high-temperature fuel cell cathode tail gas to produce oxygen. The system divides the tail gas at the cathode outlet of the high-temperature fuel cell into two streams, one of which is sent to the high-temperature ion transport membrane technology oxygen production unit to separate oxygen and send it to the gasifier, and the other is sent to the catalytic burner for combustion reaction. The energy consumption of oxygen production is reduced, and the net power generation efficiency of the entire IGFC system can be improved.

[0004] In order to improve the power generation efficiency of the IGFC system, the above method improves the relevant units of the IGFC, but does not simultaneously consider the high energy consumption of the deep air separation device under large load and the high treatment cost of CO2 in the cathode exhaust gas of the high-temperature fuel cell. In addition, the above method does not consider solving the problem of high energy consumption of the IGFC in combination with the rapid development trend of new energy, does not fundamentally solve the problem of low net output power of the IGFC, and the proposed CO2 treatment scheme has high input and operation and maintenance costs and strong environmental destructiveness.

[0005] With the accelerated promotion of the low-carbon transformation of the energy structure, the technical level and economy of new energy have been greatly improved, and the utilization of wind energy and solar energy has achieved leapfrog development. In the past five years, renewable energy has provided about 60% of the global newly added power generation. However, at the same time, due to the volatility of new energy, there is a problem of large-scale curtailment of electricity. Using a pressure swing adsorption device to separate hydrogen from coke oven gas is one of the most efficient ways of industrial hydrogen production. This technology can utilize the sulfur-tolerant shift of coke oven gas to convert organic sulfur into H2S, improving the hydrogen production and yield.

[0006] Therefore, the present invention proposes an IGFC system and method including an oxygen storage device and a pressure swing adsorption device. Summary of the Invention

[0007] The purpose of the present invention is to solve the technical problems that the net output power of the IGFC system is greatly reduced due to the large proportion of power consumption of the existing deep air separation device, the IGFC system has excessively high costs for CO2 compression, transportation and storage, and there is curtailment of electricity when a high proportion of new energy is connected to the power grid, and to propose an IGFC power generation technology including an oxygen storage device and a pressure swing adsorption device.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] A deep air separation device, including a main air compressor, a deep air separation tower, an oxygen compressor, a nitrogen compressor, a wind-solar unit, oxygen, electricity and an oxygen storage device;

[0010] The main air compressor is used to input air. The gas output end of the main air compressor is connected to the gas input end of the deep air separation tower. The gas output end of the deep air separation tower is respectively connected to the gas input end of the oxygen compressor and the gas input end of the nitrogen compressor. The gas output end of the nitrogen compressor is connected to the gas input end of the nitrogen demand element inside the IGFC system for outputting nitrogen;

[0011] The curtailed electricity of the wind-solar unit is used to supply power to the nitrogen compressor and the oxygen compressor;

[0012] The gas output end of the oxygen compressor is connected to the gas input ends of the oxygen storage device and the oxygen demand components inside the IGFC system. The gas output end of the oxygen storage device is connected to the gas input ends of the oxygen demand components inside the IGFC system for outputting oxygen.

[0013] When the device is in operation, the process is as follows:

[0014] Air enters the main air compressor and forms high-pressure gas under the compression of the main air compressor. The high-pressure gas formed by compression is sent to the cryogenic air separation tower. The cryogenic air separation tower separates nitrogen and oxygen through cooling. The nitrogen is pressurized by the nitrogen compressor to meet the requirements for transporting coal gas in the IGFC system and is used to transport the coal gas in the IGFC system. Part of the oxygen is preferentially pressurized by the oxygen compressor to meet the pressure requirements of the gasifier and the combustion chamber and is used to supply the oxygen needs of the gasifier and the combustion chamber. The other part is pressurized and stored in the oxygen storage device to consume more new energy abandoned electricity and alleviate the technical problem of the continuity of oxygen supply in devices such as the gasifier and the tail gas combustion chamber of the IGFC system.

[0015] Among them, the power requirements of the main air compressor, the nitrogen compressor, and the oxygen compressor are supplied by the abandoned electricity of the expander, the solid oxide fuel cell, the tail gas turbine, and the air turbine inside the IGFC, as well as the steam turbine unit and the wind-solar unit.

[0016] A device for consuming, transporting, and storing CO2 includes a pressure swing adsorption device and a hot gas treatment supply device with a methane synthesis device.

[0017] The output port of the pressure swing adsorption device is connected to the input port of the hot gas treatment supply device of the methane synthesis device.

[0018] The pressure swing adsorption device includes a pressure swing adsorption device pretreatment tower, a vacuum pressure swing adsorption tower, a dehumidification tower, a deoxidation tower, and hydrogen. The purified gas is input to the pressure swing adsorption device pretreatment tower. The gas output end of the pressure swing adsorption device pretreatment tower is connected to the gas input end of the vacuum pressure swing adsorption tower. The gas output end of the vacuum pressure swing adsorption tower is connected to the gas input end of the deoxidation tower. The gas output end of the deoxidation tower is connected to the gas input end of the dehumidification tower. The dehumidification tower is used to output combustion gas and hydrogen.

[0019] When the pressure swing adsorption device is in operation, the process is as follows:

[0020] The purified gas enters the pressure swing adsorption device, and after pretreatment operations such as precipitation and pressure relief in the pretreatment tower of the pressure swing adsorption device, it enters the vacuum pressure swing adsorption tower. In the vacuum pressure swing adsorption tower, the purified gas is separated into hydrogen and combustion gas mainly composed of CO and CH4. After dehumidification and deoxidation treatment in the dehumidification tower and deoxidation tower, the hydrogen enters the methane synthesis device, and the combustion gas enters the solid oxide fuel cell after heating and pressure relief, completing the hierarchical utilization of the purified gas, improving the energy utilization efficiency of the IGFC system, providing hydrogen demand for the methane synthesis device, and achieving the local consumption of CO2.

[0021] The hot gas treatment supply device including the methane synthesis device comprises a methane synthesis device, a hydrogen purchase market, a heat exchanger, a gas heating device, a gas load, a heat load, a user, a pressure pump, water vapor, water, carbon dioxide and methane;

[0022] The gas input end of the methane synthesis device is used to input hydrogen and carbon dioxide. The output end of the methane synthesis device is connected to the gas input ends of the gas heating device and the gas load. The output end of the gas heating device is connected to the input end of the heat load. The input of the heat exchanger is water vapor and water, and the output end of the heat exchanger is connected to the input end of the heat load. The output end of the heat load is connected to the input end of the user. The output end of the user is connected to the input end of the pressure pump. The output end of the pressure pump is connected to the input end of the heat load.

[0023] When the hot gas treatment supply device including the methane synthesis device is in use, the following steps are adopted:

[0024] The tail gas after heat recovery is cooled to obtain high-purity carbon dioxide, and reacts with the hydrogen generated in the methane synthesis device and the pressure swing adsorption device of the IGFC system and the hydrogen purchased from the hydrogen purchase market to generate a gas mainly composed of methane and water. After the obtained gas is cooled, a part of it is supplied to the gas load, and the other part enters the gas heating device to generate heat through combustion, and together with the heat generated by the heat exchanger, it is supplied to the heat load. Promoted by the pressure pump to meet the needs of the user, enabling the IGFC system to supply electricity, heat and gas networks simultaneously, and the IGFC has a broader application in the integrated energy system, realizing the local consumption of CO2 and reducing the costs of CO2 compression, transportation and storage of the IGFC system.

[0025] An IGFC system including an oxygen storage device and a pressure swing adsorption device, which adopts the above-mentioned deep air separation device and the above-mentioned CO2 consumption, transportation and storage device;

[0026] The input port of the deep air separation device is used to input air. The first output port of the deep air separation device is connected to the combustion chamber to provide oxygen for the combustion chamber. The second output port of the deep air separation device is used to output nitrogen to the gasifier. The third output port of the deep air separation device is used to output oxygen to the gasifier;

[0027] The inlet of the gasifier is connected to a nitrogen compressor and a coal pretreatment device, and the outlet is connected to a waste heat boiler; the outlet of the waste heat boiler is connected to a sedimentation tower; the outlet of the sedimentation tower is connected to a desulfurization device;

[0028] The inlet of the pressure swing adsorption device is connected to the desulfurization device, and the outlet is divided into two paths. One path is connected to the methane synthesis unit, and the other path is connected to an expander; the outlet of the expander is connected to a heater; the outlet of the heater is connected to a solid oxide fuel cell;

[0029] The solid oxide fuel cell is divided into an anode end and a cathode end. The inlet of the anode is connected to the heater and steam, and the outlet is connected to a combustion chamber. The inlet of the cathode is connected to an air compressor, and the outlet is connected to an air turbine. The heat energy generated by the solid oxide fuel cell is connected to a waste heat utilization device through the tail gas, and the electricity is connected to the power grid through an inverter; the inlet of the combustion chamber is connected to the oxygen storage device and the anode of the solid oxide fuel cell, and the outlet is connected to the tail gas turbine; the outlet of the tail gas turbine is connected to the waste heat utilization device, and the generated electricity is supplied to the power grid;

[0030] The inlet of the waste heat utilization device is connected to a water supply pump, an air turbine, a solid oxide fuel cell and a tail gas turbine, and the outlet is connected to the methane synthesis unit. The generated steam is supplied for use by a steam turbine unit and a heat exchanger;

[0031] The inlet of the methane synthesis unit is connected to the waste heat utilization device, the hydrogen purchase market and the pressure swing adsorption device, and the outlet is connected to a gas heating device and a gas load.

[0032] When the system is working and in use, the following steps are adopted:

[0033] Step 1: Air enters the deep air separation device of the IGFC system, forms high-pressure gas under the compression of the main air compressor, and sends the formed high-pressure gas into the deep air separation tower; the deep air separation tower separates nitrogen and oxygen through cooling. The nitrogen is pressurized by the nitrogen compressor to meet the requirements for transporting the coal gas of the IGFC system and is used to transport the coal gas of the IGFC system; part of the oxygen is pressurized by the oxygen compressor to meet the pressure requirements suitable for the gasifier and the combustion chamber and is used to supply the oxygen required by the gasifier and the combustion chamber. The other part is pressurized and stored in the oxygen storage device to consume more new energy abandoned electricity;

[0034] Step 2: Coal is crushed, ground and humidified in the coal pretreatment device to form coal slag, and is transported into the gasifier through the nitrogen compressed by the nitrogen compressor. In the high-temperature (1523.15K) and high-pressure (3MPa) environment of the gasifier, the pulverized coal reacts with the oxygen pressurized by the oxygen compressor (4) to generate raw coal gas (1573K) mainly composed of CO, H2, H2O, CH4, H2S and fly ash;

[0035] Step 3: The generated raw gas is cooled in a waste heat boiler and then enters a sedimentation tower. After being cooled in the sedimentation tower, the raw gas enters a desulfurization device. In the desulfurization device, dust, sulfides, NH3 and other impurities are removed through processes such as dust removal, water washing, COS hydrolysis, MDEA desulfurization, and fine desulfurization to obtain purified gas.

[0036] Step 4: The purified gas enters a pressure swing adsorption device. Pretreatment operations such as precipitation and pressure release are completed in the pretreatment tower of the pressure swing adsorption device, and then the purified gas enters a vacuum pressure swing adsorption tower. In the vacuum pressure swing adsorption tower, the purified gas is separated into hydrogen and combustion gas mainly composed of CO and CH4. After being dehumidified and deoxygenated in a dehumidification tower and a deoxygenation tower, the hydrogen enters a methane synthesis device, and the combustion gas enters a solid oxide fuel cell after being heated and depressurized.

[0037] Step 5: The pressure of the combustion gas is generally about 3 MPa. Therefore, before entering the solid oxide fuel cell, a part of the energy needs to be recovered through an expander expansion work device to reduce its pressure to the reaction pressure of the solid oxide fuel cell. The temperature of the combustion gas after being dehumidified and deoxygenated cannot meet the standard of the solid oxide fuel cell. Therefore, after passing through the expander expansion work device, it needs to enter a heater for heating treatment.

[0038] Step 6: For the internal reforming reaction and displacement reaction in the solid oxide fuel cell, air with a corresponding pressure needs to enter as the reaction environment. Therefore, air enters an air compressor, and after being pressurized, it is sent into the solid oxide fuel cell. The high-temperature and high-pressure air that has been used is sent into an air turbine to complete pressure release and generate electricity to supply the load demand. The high-temperature gas after pressure release is sent into a waste heat utilization device for secondary utilization of heat.

[0039] Step 7: When the combustion gas enters the anode of the solid oxide fuel cell, an electrochemical reaction occurs with the oxygen in the air entering the cathode at a pressure of about 1.5 MPa. The reforming reaction and displacement reaction occur inside the solid oxide fuel cell, directly converting chemical energy into electricity. The electricity is converted into alternating current by an inverter and sent into the power grid for distribution.

[0040] Step 8: Since the fuel in the solid oxide fuel cell cannot be fully utilized, that is, the fuel utilization rate cannot reach 100%, part of the unreacted fuel gas, together with the CO2 and H2O generated after the reaction, is sent to the combustion chamber. The combustion chamber is preferably a pure oxygen catalytic combustion chamber, which burns fully with the pure oxygen from the oxygen compressor to obtain high-pressure and high-temperature tail gas mainly composed of CO2 and H2O. The obtained tail gas first enters the tail gas turbine to do work and release pressure, and then forms a high-temperature mixed gas with the air after the air turbine completes pressure release, and the heat generated by the reaction of the solid oxide fuel cell and enters the waste heat utilization device together. The high-temperature mixed gas passes through the superheater, evaporator and economizer in the waste heat utilization device to generate steam with different temperature and pressure levels. Part of the steam enters the heat exchanger to generate heat to meet the demand of the heat load, and the other part enters the steam turbine unit to generate electricity for the power grid;

[0041] Step 9: The steam enters the steam turbine unit, absorbs the heat of the steam once through the HTP, and then absorbs the heat of the steam twice under the promotion of the pressure pump through the LTP, and generates electricity through the steam generator to provide electrical energy for the power grid;

[0042] Step 10: The tail gas after heat recovery is cooled to obtain high-purity carbon dioxide, and reacts with the hydrogen generated in the methane synthesis device and the IGFC system pressure swing adsorption device and the hydrogen purchased from the hydrogen purchase market to generate a gas mainly composed of methane and water. After the obtained gas is cooled, part of it is supplied to the gas load, and the other part enters the gas heating device to generate heat through combustion, and together with the heat exchanger for generating heat, it is supplied to the heat load, and meets the needs of users through the promotion of the pressure pump.

[0043] In Step 1, the power loads used by the main air compressor, nitrogen compressor and oxygen compressor are supplied by the expansion machine, solid oxide fuel cell, tail gas turbine and air turbine components inside the IGFC, the steam turbine unit, and the abandoned electricity of the wind and light units.

[0044] In Steps 1 to 10, the required water is provided by pressurizing with a water supply pump. Part of the water generated by the water supply pump passes through the waste heat boiler to assist in its cooling treatment and generate water vapor to meet the needs of other components such as coal transportation and solid oxide fuel cells; the other part of the water is introduced into the heat exchanger and waste heat utilization device to assist in generating water vapor.

[0045] Compared with the prior art, the present invention has the following technical effects:

[0046] 1) The present invention improves the cryogenic air separation device, uses the cryogenic air separation device to convert the new energy that cannot be consumed in time into O2, stores it in the oxygen storage device, increases the proportion of new energy consumption, reduces the consumption of the IGFC system for supplying internal components, and improves the overall net output power of the IGFC system.

[0047] 2) The present invention introduces a pressure swing adsorption device. By utilizing the ability of the IGFC system gasifier to process coal gas and combining with the sulfur-resistant shift hydrogen production technology of coke oven gas, H2 in the purified gas is extracted, and CH4 is generated in the methane synthesis device with the CO2 discharged from the oxygen-enriched combustion chamber to supply the gas load, realizing the local consumption of CO2 and reducing the costs of CO2 compression, transportation, and storage in the IGFC system.

[0048] 3) The present invention introduces a methane synthesis device, enabling the IGFC system to supply power, heat, and gas networks simultaneously, and having a broader application of IGFC in the integrated energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention will be further described below in conjunction with the drawings and embodiments:

[0050] Figure 1 Schematic structural diagram of the deep air separation device of the IGFC system with an oxygen storage device;

[0051] Figure 2 Schematic structural diagram of the pressure swing adsorption device;

[0052] Figure 3 Schematic structural diagram of the hot gas treatment supply device with a methane synthesis device;

[0053] Figure 4 Schematic structural diagram of the IGFC system with an oxygen storage device and a pressure swing adsorption device;

[0054] Figure 5 Schematic diagram of the overall structural connection of the improved IGFC system with an oxygen storage device and a pressure swing adsorption device;

[0055] Figure 6 Distribution diagram of abandoned electricity for each scenario in the embodiment;

[0056] Figure 7 Oxygen supply diagram for Scenario 4 in the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0057] As Figure 1 shown, a deep air separation device includes a main air compressor 2, a deep air separation tower 3, an oxygen compressor 4, a nitrogen compressor 5, a wind-solar unit 6, oxygen 41, electricity 48, and an oxygen storage device 52;

[0058] The main air compressor 2 is used to input air. The gas output end of the main air compressor 2 is connected to the gas input end of the cryogenic air separation tower 3. The gas output end of the cryogenic air separation tower 3 is respectively connected to the gas input end of the oxygen compressor 4 and the gas input end of the nitrogen compressor 5. The gas output end of the nitrogen compressor 5 is connected to the gas input end of the nitrogen demand element inside the IGFC system for outputting nitrogen.

[0059] The abandoned electricity of the wind-solar unit 6 is used to supply the power 48 of the nitrogen compressor 5 and the oxygen compressor 4.

[0060] The gas output end of the oxygen compressor 4 is connected to the oxygen storage device 52 and the gas input end of the oxygen demand element inside the IGFC system. The gas output end of the oxygen storage device 52 is connected to the gas input end of the oxygen demand element inside the IGFC system for outputting oxygen.

[0061] When a cryogenic air separation device is in use, the following steps are adopted:

[0062] Air enters the main air compressor 2 and forms high-pressure gas under the compression of the main air compressor 2, and the high-pressure gas formed by compression is sent into the cryogenic air separation tower 3. The cryogenic air separation tower 3 separates nitrogen and oxygen 41 through cooling. The nitrogen is pressurized by the nitrogen compressor 5 to meet the requirements for transporting coal gas in the IGFC system for transporting the coal gas of the IGFC system. A part of the oxygen 41 is preferentially pressurized by the oxygen compressor 4 to meet the pressure requirements of the gasifier 9 and the combustion chamber 20 for supplying the oxygen needs of the gasifier 9 and the combustion chamber 20, and the other part is pressurized and stored in the oxygen storage device 52 to consume more new energy abandoned electricity and relieve the technical problem of the continuity of oxygen supply in devices such as the gasifier and the tail gas combustion chamber of the IGFC system. Among them, the power demand 48 of the main air compressor 2, the nitrogen compressor 5 and the oxygen compressor 4 is supplied by the expander 17, the solid oxide fuel cell 19, the tail gas turbine 21 and the air turbine 51 inside the IGFC, as well as the abandoned electricity of the steam turbine unit 31 and the wind-solar unit 6.

[0063] Aiming at the technical problem that the cost of CO2 compression, transportation and storage in the IGFC system is too high, the present invention introduces a pressure swing adsorption device 49 and a hot gas supply module 53, uses the technology of hydrogen production by sulfur-tolerant shift of coke oven gas to extract H2 from the purified gas, and generates CH4 supply gas load with the CO2 discharged from the oxygen-enriched combustion chamber in the methane synthesis device to realize the local consumption of CO2, so that the IGFC system can supply electricity, heat and gas networks simultaneously and reduce the cost of CO2 compression, transportation and storage in the IGFC system.

[0064] Figure 2 It is a schematic structural diagram of the pressure swing adsorption device, specifically as follows:

[0065] Figure 2 It includes a pre-treatment tower 13 of a pressure swing adsorption device, a vacuum pressure swing adsorption tower 14, a dehumidification tower 15, a deoxidation tower 16, and hydrogen 44.

[0066] The purified gas is input to the pre-treatment tower 13 of the pressure swing adsorption device. The gas output end of the pre-treatment tower 13 of the pressure swing adsorption device is connected to the gas input end of the vacuum pressure swing adsorption tower 14. The gas output end of the vacuum pressure swing adsorption tower 14 is connected to the gas input end of the deoxidation tower 16. The gas output end of the deoxidation tower 16 is connected to the gas input end of the dehumidification tower 15. The dehumidification tower 15 is used to output combustion gas and hydrogen 44.

[0067] When the pressure swing adsorption device is in use, the following steps are adopted:

[0068] The purified gas enters the pressure swing adsorption device 49, and completes pre-treatment operations such as precipitation and pressure release in the pre-treatment tower 13 of the pressure swing adsorption device and then enters the vacuum pressure swing adsorption tower 14. In the vacuum pressure swing adsorption tower 14, the purified gas is separated into hydrogen 44 and combustion gas mainly composed of CO and CH4. After the dehumidification and deoxidation treatment by the dehumidification tower 15 and the deoxidation tower 16, hydrogen 44 enters the methane synthesis device 32, and the combustion gas enters the solid oxide fuel cell 19 after heating and pressure release, completing the hierarchical utilization of the purified gas, improving the energy utilization efficiency of the IGFC system, and providing hydrogen demand for the methane synthesis device 32 to achieve the in-situ consumption of CO2.

[0069] Figure 3 It is a schematic structural diagram of a hot gas treatment supply device including a methane synthesis device, specifically as follows:

[0070] Figure 3 It includes a methane synthesis device 32, a hydrogen purchase market 33, a heat exchanger 34, a gas heating device 35, a gas load 36, a heat load 37, a user 38, a pressure pump 39, water vapor 42, water 45, carbon dioxide 46, and methane 47.

[0071] The gas input end of the methane synthesis device 32 is used to input hydrogen 44 and carbon dioxide 46. The output end of the methane synthesis device 32 is connected to the gas input ends of the gas heating device 35 and the gas load 36. The output end of the gas heating device 35 is connected to the input end of the heat load 37. The input of the heat exchanger 34 is water vapor 42 and water 45. The output end of the heat exchanger 34 is connected to the input end of the heat load 37. The output end of the heat load 37 is connected to the input end of the user 38. The output end of the user 38 is connected to the input end of the pressure pump 39. The output end of the pressure pump 39 is connected to the input end of the heat load 37.

[0072] When the hot gas treatment supply device including a methane synthesis device is in use, the following steps are adopted:

[0073] The tail gas after heat recovery is cooled to obtain high-purity carbon dioxide 46, which reacts with hydrogen 44 generated in the methane synthesis device 32 and the pressure swing adsorption device 49 of the IGFC system and hydrogen 44 purchased from the hydrogen purchase market 33 to generate a gas mainly composed of methane 47 and water. After the obtained gas is cooled, a part of it is supplied to the gas load 36, and the other part enters the gas heating device 35 to generate heat through combustion. Together with the heat exchanger 34 for generating heat, it is supplied to the heat load 37. Promoted by the pressure pump 39, it meets the needs of users 38, enabling the IGFC system to supply electricity, heat, and gas networks simultaneously. The IGFC has a broader application in the integrated energy system, realizing the local consumption of CO2 and reducing the costs of CO2 compression, transportation, and storage in the IGFC system;

[0074] Figure 4 It is a schematic structural diagram of an IGFC system including an oxygen storage device and a pressure swing adsorption device, which includes an improved cryogenic air separation device 1, a coal pretreatment device 7, coal 8, a gasifier 9, a waste heat boiler 10, a desulfurization device 11, a sedimentation tower 12, an expander 17, a heater 18, a solid oxide fuel cell 19, a combustion chamber 20, a tail gas turbine 21, an inverter 22, a waste heat utilization device 23, a superheater 24, an evaporator 25, an economizer 26, a pressure pump 27, HTP 28, LTP 29, a steam generator 30, a steam turbine unit 31, a water supply pump 40, oxygen 41, steam 42, coal slag 43, hydrogen 44, water 45, carbon dioxide 46, electricity 48, a pressure swing adsorption device 49, an air compressor 50, an air turbine 51, an oxygen storage device 52, and a hot gas supply module 53.

[0075] The input port of the cryogenic air separation device 1 is used to input air. The first output port of the cryogenic air separation device 1 is connected to the combustion chamber 20 to supply oxygen to the combustion chamber 20. The second output port of the cryogenic air separation device 1 is used to output nitrogen to the gasifier 9, and the third output port of the cryogenic air separation device 1 is used to output oxygen to the gasifier 9;

[0076] Specifically, the cryogenic air separation device 1 includes a cryogenic air separation tower 3. The inlet of the cryogenic air separation tower 3 is connected to the main air compressor 2, and the outlet is connected to the oxygen compressor 4 and the nitrogen compressor 5. The power source of the oxygen compressor 4 includes a wind-solar unit 6 and the generator set of the IGFC system. The oxygen outlet is divided into two paths. One path supplies the process of heating and gasifying coal in the gasifier 9 to generate raw gas, and the other path is connected to the oxygen storage device 52 for storage.

[0077] The outlet of the oxygen storage device 52 is divided into two paths. One path is connected to the gasifier 9 of the IGFC system, and the other path is connected to the combustion chamber 20 for further purifying carbon dioxide from the tail gas. The inlet of the gasifier 9 is connected to the nitrogen compressor 5 and the coal pretreatment device 7, and the outlet is connected to the waste heat boiler 10. The outlet of the waste heat boiler 10 is connected to the precipitation tower 12. The outlet of the precipitation tower 12 is connected to the desulfurization device 11.

[0078] The inlet of the pressure swing adsorption device 49 is connected to the desulfurization device 11, and the outlet is divided into two paths. One path is connected to the methane synthesis converter 32, and the other path is connected to the expander 17. The outlet of the expander 17 is connected to the heater 18. The outlet of the heater is connected to the solid oxide fuel cell 19.

[0079] The solid oxide fuel cell 19 is divided into an anode end and a cathode end. The inlet of the anode is connected to the heater 18 and the water vapor 42, and the outlet is connected to the combustion chamber 20. The inlet of the cathode is connected to the air compressor 50, and the outlet is connected to the air turbine 51. The heat energy generated by the solid oxide fuel cell 19 is connected to the waste heat utilization device 23 through the tail gas, and the electricity is connected to the power grid through the inverter 22. The inlet of the combustion chamber 20 is connected to the oxygen storage device 52 and the anode of the solid oxide fuel cell 19, and the outlet is connected to the tail gas turbine 21. The outlet of the tail gas turbine 21 is connected to the waste heat utilization device 23, and the generated electricity is supplied to the power grid.

[0080] The inlet of the waste heat utilization device 23 is connected to the water supply pump 40, the air turbine 51, the solid oxide fuel cell 19, and the tail gas turbine 21, and the outlet is connected to the methane synthesis converter 32. The generated water vapor is supplied for use in the steam turbine unit 31 and the heat exchanger 34.

[0081] The inlet of the methane synthesis converter 32 is connected to the waste heat utilization device 23, the hydrogen purchase market 33, and the pressure swing adsorption device 49, and the outlet is connected to the gas heating device 35 and the gas load 36.

[0082] The present invention makes full use of the functions of the IGFC system, simultaneously meets the supply of electricity, heat, and gas energy in the integrated energy system, and utilizes the hydrogen in the purified gas of the IGFC system to treat the CO2 generated in the tail gas, realizing multi-level applications of the IGFC system;

[0083] An operation method for an IGFC system including an oxygen storage device and a pressure swing adsorption device includes the following steps:

[0084] Step 1: Air enters the deep cryogenic air separation device of the IGFC system, forms high-pressure gas under the compression of the main air compressor 2, and sends the high-pressure gas formed by compression into the deep cryogenic air separation tower 3. The deep cryogenic air separation tower 3 separates nitrogen and oxygen 41 through cooling. The nitrogen is pressurized by the nitrogen compressor 5 to meet the requirements for transporting coal gas in the IGFC system and is used to transport the coal gas of the IGFC system; part of the oxygen 41 is preferentially pressurized by the oxygen compressor 4 to meet the pressure requirements of the gasifier 9 and the combustion chamber 20 and is used to supply the oxygen needs of the gasifier 9 and the combustion chamber 20. The other part is pressurized and stored in the oxygen storage device 52 to consume more new energy abandoned electricity and alleviate the technical problem of the continuity of oxygen supply in devices such as the gasifier and the tail gas combustion chamber of the IGFC system.

[0085] The electric loads used by the main air compressor 2, the nitrogen compressor 5, and the oxygen compressor 4 in Step 1 are supplied by the abandoned electricity of the expander 17, the solid oxide fuel cell 19, the tail gas turbine 21, the air turbine 51 components, the steam turbine unit 31, and the wind and light unit 6 inside the IGFC.

[0086] Step 2: Coal 8 is crushed, ground, and humidified in the coal pretreatment device 7 to form coal slag 43, and is transported into the gasifier 9 through the nitrogen compressed by the nitrogen compressor 5. In the high-temperature (1523.15K) and high-pressure (3MPa) environment of the gasifier 9, the pulverized coal reacts with the oxygen pressurized by the oxygen compressor 4 to generate raw coal gas (1573K) mainly composed of CO, H2, H2O, CH4, H2S, and fly ash.

[0087] Step 3: The generated raw coal gas is cooled by the waste heat boiler 10 and enters the sedimentation tower 12. After being cooled in the sedimentation tower 12, the raw coal gas enters the desulfurization device 11. In the desulfurization device 11, dust, sulfides, NH3 and other impurities are removed through processes such as dust removal, water washing, COS hydrolysis, MDEA desulfurization, and fine desulfurization to obtain purified gas.

[0088] Step 4: The purified gas enters the pressure swing adsorption device 49, completes pretreatment operations such as precipitation and pressure release in the pretreatment tower 13 of the pressure swing adsorption device and enters the vacuum pressure swing adsorption tower 14. In the vacuum pressure swing adsorption tower 14, the purified gas is separated into hydrogen 44 and combustion gas mainly composed of CO and CH4. After being dehumidified and deoxygenated by the dehumidification tower 15 and the deoxygenation tower 16, the hydrogen 44 enters the methane synthesis device 32, and the combustion gas enters the solid oxide fuel cell 19 after being heated and depressurized.

[0089] Step 5: The pressure of the combustion gas is generally about 3 MPa. Therefore, before entering the solid oxide fuel cell 19, a part of the energy needs to be recovered through the expansion work device of the expander 17 to reduce its pressure to the reaction pressure of the solid oxide fuel cell 19. The temperature of the combustion gas after dehumidification and deoxidation treatment cannot meet the standard of the solid oxide fuel cell 19. Therefore, after passing through the expansion work device of the expander 17, it needs to enter the heater 18 for heating treatment.

[0090] Step 6: For the reforming reaction and displacement reaction to occur inside the solid oxide fuel cell 19, air with a corresponding pressure needs to enter as the reaction environment. Therefore, the air enters the air compressor 50, and after being pressurized, it is sent into the solid oxide fuel cell 19. The high-temperature and high-pressure air that has been used is sent into the air turbine 51 to complete pressure release and generate electricity to supply the load demand. The high-temperature gas after pressure release is then sent into the waste heat utilization device 23 for secondary utilization of heat.

[0091] Step 7: When the combustion gas enters the anode of the solid oxide fuel cell 19, an electrochemical reaction occurs with the oxygen in the air entering the cathode at a pressure of about 1.5 MPa. The reforming reaction and displacement reaction occur inside the solid oxide fuel cell 19, directly converting chemical energy into electricity 48. The electricity 48 is converted into alternating current by the inverter 22 and sent into the power grid for distribution.

[0092] Step 8: Since the fuel in the solid oxide fuel cell 19 cannot be fully utilized, that is, the fuel utilization rate cannot reach 100%, part of the unreacted fuel gas, together with the CO2 and H2O generated after the reaction, is sent into the combustion chamber 20. The combustion chamber 20 is preferably a pure oxygen catalytic combustion chamber, and it burns fully with the pure oxygen from the oxygen compressor 4 to obtain high-pressure and high-temperature tail gas mainly composed of CO2 and H2O. The obtained tail gas first enters the tail gas turbine 21 for turbine work and pressure release, and then forms a high-temperature mixed gas together with the air after pressure release by the air turbine 51 and the heat generated by the reaction of the solid oxide fuel cell 19, and enters the waste heat utilization device 23. The high-temperature mixed gas passes through the superheater 24, evaporator 25, and economizer 26 in the waste heat utilization device to generate steam with different temperature and pressure levels. Part of it enters the heat exchanger 34 to generate heat to supply the demand of the heat load 37, and the other part enters the steam turbine unit 31 to generate electricity 48 to supply the power grid.

[0093] Step 9: The steam enters the steam turbine unit 31, absorbs the heat of the steam once through the HTP28, and then absorbs the heat of the steam twice under the promotion of the pressure pump 27 through the LTP29, and generates electricity 48 through the steam generator 30 to provide electrical energy for the power grid.

[0094] Step 10: The tail gas after heat recovery is cooled to obtain high-purity carbon dioxide 46, which reacts with hydrogen 44 generated in the methane synthesis device 32 and the pressure swing adsorption device 49 of the IGFC system and hydrogen 44 purchased from the hydrogen purchase market 33 to generate a gas mainly composed of methane 47 and water. After the obtained gas is cooled, a part of it is supplied to the gas load 36, and the other part enters the gas heating device 35 to generate heat through combustion, and together with the heat generated by the heat exchanger 34, it is supplied to the heat load 37, and is promoted by the pressure pump 39 to meet the needs of the user 38.

[0095] The water required for the above steps is provided by pressurizing with the water supply pump 40. A part of the water 45 generated by the water supply pump 40 passes through the waste heat boiler 10 to assist in its cooling treatment and generate steam 42 to meet the needs of other components such as coal transportation and the solid oxide fuel cell 19; the other part of the water is introduced into the heat exchanger 34 and the waste heat utilization device 23 to assist in generating steam 42.

[0096] An IGFC system including an oxygen storage device and a pressure swing adsorption device uses a deep air separation device to convert new energy that cannot be consumed in time into O2, stores it in the oxygen storage tank, increases the proportion of new energy consumption, and reduces the consumption of the IGFC system for supplying internal components; at the same time, using the gasification furnace of the IGFC system to process coal gas, combined with the hydrogen production technology of the sulfur-resistant shift of coke oven gas to extract H2 from the purified gas, and generating CH4 in the methane synthesis device with the CO2 discharged from the oxygen-enriched combustion chamber to supply the gas load, realizing the local consumption of CO2.

[0097] Example:

[0098] Taking a typical area in northern China as an example, this invention sets four different configurations of the IGFC system to verify the performance advantages of the improved IGFC system in the typical daily supply in the IES. The four scenarios set are:

[0099] Scenario 1: Coupled new energy and traditional IGFC system scheduling scenario: Using a carbon capture system to achieve the treatment of CO2.

[0100] Scenario 2: IGFC system carbon local treatment scenario: On the basis of Scenario 1, replacing the carbon capture system with an oxygen-enriched combustion chamber and a methane treatment device, and realizing the local consumption of CO2 by purchasing hydrogen.

[0101] Scenario 3: IGFC system assisted carbon treatment scenario: On the basis of Scenario 2, introducing a pressure swing adsorption device to realize the local use of hydrogen by separating hydrogen from the purified gas.

[0102] Scenario 4: Improved IGFC system scenario: On the basis of Scenario 3, introducing an oxygen storage device, and using the abandoned electricity of new energy to supply the air separation device to generate and store high-pressure oxygen.

[0103] Considering the sharp increase in electricity load and the large gap between peak and valley loads, a gradient pricing is adopted for electricity load; an average price within the day is adopted for heat load and gas load; an average price within the day is adopted for coal and hydrogen. The 24-hour gradient price distributions of electricity, heat, gas, and coal within the day are shown in Table 1 as follows.

[0104] Table 1 Gradient Price Table of Electricity, Heat, Gas, and Coal within the Day

[0105]

[0106] The parameter distributions of each unit are as Figure 2 shown.

[0107] Table 2 Parameter Distributions of Each Unit

[0108]

[0109] The equipment parameter distributions are as Figure 3 shown.

[0110] Table 3 Equipment Parameter Distributions

[0111]

[0112] Table 4 shows the cost distribution results of four scenarios. The operation and maintenance costs, dispatching costs, carbon emission costs, and total costs from Scenario 1 to Scenario 4 decrease in turn, verifying the economic advantages of the improved IGFC system during the operation on a typical day. Among them, the curtailment penalty costs from Scenario 2 to Scenario 4 decrease in turn. This is because a pressure swing adsorption device is introduced in Scenario 3 to separate hydrogen from the purified gas of the IGFC system, resulting in a decrease in the power generation of the SOFC. The IES consumes more new energy, so the generated curtailment is relatively reduced; in Scenario 4, the improved IGFC system further processes the new energy curtailment by introducing an oxygen storage device. However, the IGFC system in Scenario 2 only introduces a methane synthesis device, lacking the power consumption of the carbon capture system compared with Scenario 1, resulting in some new energy being unable to be consumed in time. Therefore, the curtailment penalty cost in Scenario 2 is higher than that in Scenario 1.

[0113] Table 4 Day-ahead Dispatching Cost Distributions of Each Scenario (in thousand yuan)

[0114]

[0115] This section presents the average in-plant power consumption efficiency within the day of four scenarios as shown in Table 5.

[0116] Table 5 Average In-Plant Power Consumption Efficiency of Each Scenario within the Day (%)

[0117]

[0118] As can be seen from the table, the plant power consumption of the desulfurization device and the air compression device from Scenario 1 to Scenario 4 is relatively stable. Since the methane synthesis device is equipped in Scenarios 2 to 4, the problem of high plant power consumption in the carbon capture system is solved. Coupled with the oxygen storage device equipped in Scenario 4, the new energy abandoned electricity is further utilized to replace the oxygen generated by the IGFC system to supply the internal components, resulting in a further reduction in the plant power consumption of the air separation device of the improved IGFC system and a further increase in the net plant output, verifying the advantage of the improved IGFC system in the overall power generation efficiency.

[0119] The abandoned electricity of the four designed scenarios is as Figure 6 shown.

[0120] From Figure 6 it can be seen that the abandoned electricity of the integrated energy is mainly concentrated in the periods of 24:00 - 6:00 and 11:00 - 15:00. This is because the electricity load is relatively low from 24:00 - 6:00, and the wind energy output is high at night. Even if the system converts and stores the unconsumed wind energy at this time, there will still be some abandoned electricity generated; 11:00 - 15:00 is the golden period of light energy output. At this time, the electricity load is higher than the daily load, but it is not enough to consume all the light energy, thus generating some abandoned electricity. The improved IGFC system makes full use of the function of the oxygen storage device, further consumes some abandoned electricity, reduces the waste of energy, and balances the system output.

[0121] The improved IGFC system introduces an oxygen storage device, converts the new energy abandoned electricity into oxygen and stores it, and jointly undertakes the oxygen supply with the improved IGFC system. The oxygen supply distribution of the improved IGFC system is as Figure 7 .

[0122] It can be obtained from the figure that in the periods of 24:00 - 6:00 and 11:00 - 15:00 when the abandoned electricity is relatively concentrated, the improved IGFC system uses the air separation device to convert part of the abandoned electricity into O2 to supply the needs of the internal components of the improved IGFC system, and stores the unconsumed O2 in the oxygen storage device. At the peak moment of O2 use, the O2 stored in the oxygen storage device is released to replace the demand for the air separation device of the improved IGFC system to supply the internal components, improving the overall net output power of the improved IGFC system.

Claims

1. A deep air separation device, characterized in that, It includes a main air compressor, a cryogenic air separation tower, an oxygen compressor, a nitrogen compressor, a wind-solar unit, oxygen, electricity, and an oxygen storage device; The main air compressor is used to input air. The gas output end of the main air compressor is connected to the gas input end of the cryogenic air separation tower. The gas output end of the cryogenic air separation tower is respectively connected to the gas input end of the oxygen compressor and the gas input end of the nitrogen compressor. The gas output end of the nitrogen compressor is connected to the gas input end of the nitrogen demand element inside the IGFC system for outputting nitrogen; The curtailed electricity of the wind-solar unit is used to supply power to the nitrogen compressor and the oxygen compressor; The gas output end of the oxygen compressor is connected to the oxygen storage device and the gas input end of the oxygen demand element inside the IGFC system. The gas output end of the oxygen storage device is connected to the gas input end of the oxygen demand element inside the IGFC system for outputting oxygen.

2. The deep air separation device according to claim 1, characterized in that, When this device is in operation, the process is as follows: Air enters the main air compressor and forms high-pressure gas under the compression of the main air compressor, and the high-pressure gas formed by compression is sent into the cryogenic air separation tower; the cryogenic air separation tower separates nitrogen and oxygen through cooling. The nitrogen is pressurized by the nitrogen compressor to meet the requirements for transporting coal gas in the IGFC system for transporting the coal gas in the IGFC system; part of the oxygen is preferentially pressurized by the oxygen compressor to meet the pressure requirements of the gasifier and the combustion chamber for supplying the oxygen needs of the gasifier and the combustion chamber, and the other part is pressurized and stored in the oxygen storage device to consume more curtailed new energy electricity; Among them, the power demands of the main air compressor, the nitrogen compressor, and the oxygen compressor are supplied by the expander, the solid oxide fuel cell, the tail gas turbine, the air turbine inside the IGFC, as well as the curtailed electricity of the steam turbine unit and the wind-solar unit.

3. A device for the consumption, transportation, and storage of CO2, characterized in that, It includes a pressure swing adsorption device and a hot gas treatment supply device with a methane synthesis device; The output port of the pressure swing adsorption device is connected to the input port of the hot gas treatment supply device with a methane synthesis device; The pressure swing adsorption device includes a pressure swing adsorption device pretreatment tower, a vacuum pressure swing adsorption tower, a dehumidification tower, a deoxidation tower, and hydrogen; the purified gas is input to the pressure swing adsorption device pretreatment tower. The gas output end of the pressure swing adsorption device pretreatment tower is connected to the gas input end of the vacuum pressure swing adsorption tower. The gas output end of the vacuum pressure swing adsorption tower is connected to the gas input end of the deoxidation tower. The gas output end of the deoxidation tower is connected to the gas input end of the dehumidification tower. The dehumidification tower is used to output combustion gas and hydrogen.

4. The device according to claim 3, characterized in that, When the pressure swing adsorption device is in operation, the process is as follows: The purified gas enters the pressure swing adsorption device, and after completing pretreatment operations such as precipitation and pressure release in the pressure swing adsorption device pretreatment tower, it enters the vacuum pressure swing adsorption tower. In the vacuum pressure swing adsorption tower, the purified gas is separated into hydrogen and combustion gas mainly composed of CO and CH4. After the dehumidification and deoxidation treatments in the dehumidification tower and the deoxidation tower, the hydrogen enters the methane synthesis device, and the combustion gas enters the solid oxide fuel cell after heating and pressure release, completing the hierarchical utilization of the purified gas, improving the energy utilization efficiency of the IGFC system, and providing hydrogen demand for the methane synthesis device to achieve the in-situ consumption of CO2.

5. The device according to claim 3, characterized in that, The hot gas treatment supply device of the methane synthesis device includes a methane synthesis device, a hydrogen purchase market, a heat exchanger, a gas heating device, a gas load, a heat load, a user, a pressure pump, water vapor, water, carbon dioxide, and methane; The gas input end of the methane synthesis device is used to input hydrogen and carbon dioxide. The output end of the methane synthesis device is connected to the gas input ends of the gas heating device and the gas load. The output end of the gas heating device is connected to the input end of the heat load. The inputs of the heat exchanger are water vapor and water, and the output end of the heat exchanger is connected to the input end of the heat load. The output end of the heat load is connected to the input end of the user. The output end of the user is connected to the input end of the pressure pump. The output end of the pressure pump is connected to the input end of the heat load.

6. The device according to claim 5, characterized in that, When the hot gas treatment supply device of the methane synthesis device is in use, the following steps are adopted: The tail gas after heat recovery is cooled to obtain high-purity carbon dioxide, and reacts with the hydrogen generated in the methane synthesis device and the IGFC system pressure swing adsorption device and the hydrogen purchased from the hydrogen purchase market to generate a gas mainly composed of methane and water. After the obtained gas is cooled, a part is supplied to the gas load, and the other part enters the gas heating device to generate heat through combustion, and is supplied to the heat load together with the heat generated by the heat exchanger. Promoted by the pressure pump to meet the needs of users, enabling the IGFC system to supply electricity, heat, and gas networks simultaneously, and the IGFC has a broader application in the integrated energy system, realizing the local consumption of CO2 and reducing the costs of CO2 compression, transportation, and storage in the IGFC system.

7. An IGFC system comprising an oxygen storage device and a pressure swing adsorption device, characterized in that, This system adopts the deep air separation device described in claim 1 or 2, and the CO2 consumption, transportation, and storage device described in any one of claims 3 to 6; The input port of the deep air separation device is used to input air. The first output port of the deep air separation device is connected to the combustion chamber to provide oxygen for the combustion chamber. The second output port of the deep air separation device is used to output nitrogen to the gasifier. The third output port of the deep air separation device is used to output oxygen to the gasifier; The inlet of the gasifier is connected to a nitrogen compressor and a coal pretreatment device, and the outlet is connected to a waste heat boiler; the outlet of the waste heat boiler is connected to a sedimentation tower; the outlet of the sedimentation tower is connected to a desulfurization device; The inlet of the pressure swing adsorption device is connected to the desulfurization device, and the outlet is divided into two paths. One path is connected to the methane synthesis conversion device, and the other path is connected to an expander; the outlet of the expander is connected to a heater; the outlet of the heater is connected to a solid oxide fuel cell; The solid oxide fuel cell is divided into an anode end and a cathode end. The inlet of the anode is connected to the heater and water vapor, and the outlet is connected to the combustion chamber. The inlet of the cathode is connected to an air compressor, and the outlet is connected to an air turbine. The heat energy generated by the solid oxide fuel cell is connected to a waste heat utilization device through the tail gas, and the electricity is connected to the power grid through an inverter; the inlet of the combustion chamber is connected to an oxygen storage device and the anode of the solid oxide fuel cell, and the outlet is connected to a tail gas turbine; the outlet of the tail gas turbine is connected to the waste heat utilization device, and the generated electricity is supplied to the power grid; The inlet of the waste heat utilization device is connected to a water supply pump, an air turbine, a solid oxide fuel cell, and an exhaust gas turbine, and the outlet is connected to a methane synthesis unit. The generated steam is supplied for use in a steam turbine unit and a heat exchanger; The inlet of the methane synthesis unit is connected to the waste heat utilization device, a hydrogen purchase market, and a pressure swing adsorption device, and the outlet is connected to a gas heating device and a gas load.

8. The system according to claim 7, wherein When this system is working and in use, the following steps are adopted: Step 1: Air enters the cryogenic air separation device of the IGFC system and forms high-pressure gas under the compression of the main air compressor. The formed high-pressure gas is sent into the cryogenic air separation tower. The cryogenic air separation tower separates nitrogen and oxygen through cooling. The nitrogen is pressurized by a nitrogen compressor to meet the requirements for transporting coal gas in the IGFC system and is used to transport the coal gas in the IGFC system. A part of the oxygen is preferentially pressurized by an oxygen compressor to meet the pressure requirements of the gasifier and the combustion chamber and is used to supply the oxygen needs of the gasifier and the combustion chamber. Another part is pressurized and stored in an oxygen storage device to consume more new energy abandoned electricity; Step 2: Coal is crushed, ground, and humidified in a coal pretreatment device to form coal slag, which is transported into the gasifier through nitrogen compressed by a nitrogen compressor. In the high-temperature and high-pressure environment of the gasifier, the pulverized coal reacts with the oxygen pressurized by the oxygen compressor to generate raw coal gas mainly composed of CO, H2, H2O, CH4, H2S, and fly ash; Step 3: The generated raw coal gas is cooled in a waste heat boiler and enters a sedimentation tower. After being cooled in the sedimentation tower, the raw coal gas enters a desulfurization device, and in the desulfurization device, dust, sulfides, NH3 and other impurities are removed through processes such as dust removal, water washing, COS hydrolysis, MDEA desulfurization, and fine desulfurization to obtain purified gas; Step 4: The purified gas enters a pressure swing adsorption device. After pretreatment operations such as precipitation and pressure release are completed in the pretreatment tower of the pressure swing adsorption device, it enters a vacuum pressure swing adsorption tower. In the vacuum pressure swing adsorption tower, the purified gas is separated into hydrogen and combustion gas mainly composed of CO and CH4. After dehumidification and deoxygenation treatment in a dehumidification tower and a deoxygenation tower, the hydrogen enters a methane synthesis device, and the combustion gas enters a solid oxygen fuel cell after being heated and depressurized; Step 5: Before the combustion gas enters the solid oxygen fuel cell, it needs to pass through an expander expansion work device to recover a part of the energy and reduce its pressure to the reaction pressure of the solid oxygen fuel cell. The temperature of the combustion gas after dehumidification and deoxygenation treatment cannot meet the standard of the solid oxygen fuel cell, so it needs to enter a heater for heating treatment after passing through the expander expansion work device; Step 6: Corresponding pressure air needs to enter the solid oxygen fuel cell as the reaction environment for the reforming reaction and displacement reaction inside the solid oxygen fuel cell. Therefore, air enters an air compressor, is pressurized and sent into the solid oxygen fuel cell after the reaction. The used high-temperature and high-pressure air is sent into an air turbine to complete pressure release to generate electricity to supply the load demand, and the high-temperature gas after pressure release is sent into the waste heat utilization device for secondary utilization of heat; Step 7: When the combustion gas enters the anode of the solid oxide fuel cell, it undergoes an electrochemical reaction with the oxygen in the air entering the cathode. A reforming reaction and a displacement reaction occur inside the solid oxide fuel cell, directly converting chemical energy into electricity. The electricity is converted into alternating current by an inverter and sent into the power grid for distribution; Step 8: Since the fuel in the solid oxide fuel cell cannot be fully utilized, that is, the fuel utilization rate cannot reach 100%, part of the unreacted fuel gas, together with the CO2 and H2O generated after the reaction, is sent into the combustion chamber and burns fully with the pure oxygen from the oxygen compressor. A high-pressure and high-temperature tail gas mainly composed of CO2 and H2O is obtained. The obtained tail gas first enters the tail gas turbine to perform work and release pressure. Then, it forms a high-temperature mixed gas together with the air that has completed pressure release in the air turbine and the heat generated by the reaction of the solid oxide fuel cell and enters the waste heat utilization device. The high-temperature mixed gas passes through a superheater, an evaporator, and an economizer in the waste heat utilization device to generate steam with different temperature and pressure levels. Part of the steam enters the heat exchanger to generate heat to meet the demand of the heat load, and the other part enters the steam turbine unit to generate electricity for the power grid; Step 9: The steam enters the steam turbine unit, absorbs the heat of the steam once through the HTP, and then absorbs the heat of the steam twice under the promotion of the pressure pump through the LTP, and generates electricity through the steam generator to provide electrical energy for the power grid; Step 10: The tail gas after heat recovery is cooled to obtain high-purity carbon dioxide, and reacts with the hydrogen generated in the methane synthesis device and the IGFC system pressure swing adsorption device and the hydrogen purchased from the hydrogen purchase market to generate a gas mainly composed of methane and water. The obtained gas is cooled, and part of it is supplied to the gas load, and the other part enters the gas heating device to generate heat through combustion, and supplies the heat load together with the heat generated by the heat exchanger, and meets the needs of users under the promotion of the pressure pump.

9. The system according to claim 8, characterized in that In Step 1, the power loads used by the main air compressor, nitrogen compressor, and oxygen compressor are supplied by the waste electricity of the expander, solid oxide fuel cell, tail gas turbine, air turbine components, steam turbine unit, and wind-solar unit inside the IGFC.

10. The system according to claim 8, characterized in that In Steps 1 to 10, the required water is provided by pressurizing with a water supply pump. Part of the water generated by the water supply pump passes through the waste heat boiler to assist in its cooling treatment and generate water vapor to meet the needs of other components such as coal transportation and solid oxide fuel cells; the other part of the water is introduced into the heat exchanger and the waste heat utilization device to assist in generating water vapor.

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