Chemical looping combustion power generation system and method

Abstract

The invention relates to the technical field of power generation systems, in particular to a chemical looping combustion power generation system and method. Comprising a feeding unit and a tail gas purification unit, the feeding unit is connected with a chemical looping combustion unit, and the chemical looping combustion unit comprises an air reactor and a fuel reactor; a high-temperature steam outlet of the chemical looping combustion unit is connected with the power generation unit; the tail gas purification unit comprises a first tail gas dust remover, a second tail gas dust remover and a tail gas desulfurization device; the air reactor is connected with a first tail gas dust remover, and the first tail gas dust remover is connected with a flue gas treatment system in the power generation unit; the fuel reactor is connected with the second tail gas dust remover, the second tail gas dust remover is connected with the tail gas desulfurization device, and the tail gas desulfurization device is connected with the CO2 trapping unit. The chemical looping combustion system is coupled with the power generation system, on one hand, engineering application of the chemical looping combustion system is achieved, on the other hand, the carbon emission of a power plant is reduced, and efficient capture of carbon dioxide is achieved.

Description

Technical Field

[0001] This invention relates to the field of power generation system technology, and in particular to a chemical looping combustion power generation system and method. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) is a crucial means of achieving the "dual carbon" goal (carbon reduction, carbon emissions, and carbon sequestration). Energy consumption and cost account for over 70% of the entire CCUS chain, making the development of low-energy, low-cost carbon capture technologies key to the large-scale application of CCUS. Chemical looping combustion is a disruptive carbon capture technology where an oxygen carrier circulates between an air reactor and a fuel reactor, transferring oxygen from the air to the fuel, avoiding direct contact between air and fuel, and exhibiting internal CO2 separation characteristics. The chemical looping reaction process prevents CO2 in the flue gas from being diluted by N2 in the air, enabling CO2 capture at the source of fuel conversion, thus resulting in lower CO2 capture energy consumption and cost.

[0003] Currently, most chemical looping combustion systems focus on gasifying fuels (such as coal and biomass) before burning them to generate electricity (e.g., patent documents with application numbers 201410030475.5, 202210762479.7, and 202410112887.7). This increases the process flow of the chemical looping combustion system, and the combustible gases such as carbon monoxide and hydrogen generated after fuel gasification increase the safety risks of the system.

[0004] Existing chemical looping combustion systems are mostly used to verify the operational feasibility of chemical looping combustion systems by achieving combustion operation within their own systems. They remain in the pilot stage and have not been connected to the steam turbine power generation system of power plants, thus failing to truly realize the role of chemical looping combustion technology in carbon emission reduction in thermal power plants.

[0005] To address the above problems, this invention is proposed. Summary of the Invention

[0006] The first objective of this invention is to provide a chemical looping combustion power generation system that couples a chemical looping combustion unit with a steam turbine power generation unit in a thermal power plant, realizing the engineering application of chemical looping combustion technology in the field of thermal power generation. This system also features lower CO2 capture energy consumption and cost, and does not increase system safety risks. The second objective of this invention is to provide a chemical looping combustion power generation method.

[0007] This invention provides a chemical loop combustion power generation system, including a feeding unit and a tail gas purification unit. The feeding unit is connected to the chemical loop combustion unit, which includes an air reactor and a fuel reactor. The high-temperature steam outlet of the chemical loop combustion unit is connected to the steam turbine of the power generation unit through a pipeline. The tail gas purification unit includes a first tail gas dust collector, a second tail gas dust collector, and a tail gas desulfurization device. The exhaust gas outlet of the air reactor is connected to the first exhaust gas dust collector via a pipeline, and the outlet of the first exhaust gas dust collector is connected to the flue gas treatment system in the power generation unit via a pipeline; the exhaust gas outlet of the fuel reactor is connected to the second exhaust gas dust collector via a pipeline, and the outlet of the second exhaust gas dust collector is connected to the exhaust gas desulfurization device via a pipeline, and the exhaust gas desulfurization device is connected to the CO2 capture unit via a pipeline.

[0008] Furthermore, the power generation unit includes a boiler, an air preheater, the flue gas treatment system, and a steam turbine connected in sequence via pipelines. The flue gas treatment system includes a dust collector, a desulfurization tower, and a chimney connected in sequence via pipelines.

[0009] Furthermore, the power generation unit also includes a high-temperature reheater connected to the steam turbine, and the high-temperature steam outlet of the chemical loop combustion unit is connected to the high-temperature reheater via a pipeline.

[0010] Furthermore, the turbine's drain outlet is connected to the chemical loop combustion unit via a pipe.

[0011] Furthermore, the high-temperature steam generated by the chemical loop combustion unit has a temperature of 520℃-630℃ and a pressure of ≥9.2MPa.

[0012] Furthermore, the feeding unit includes an oxygen carrier feeding module and a fuel feeding module. The fuel feeding module uses solid fuel, including at least one of coal or co-fired biomass and sludge. The particle size of the solid fuel is ≤5mm.

[0013] Furthermore, the carbon dioxide outlet of the CO2 capture unit is connected to the chemical loop combustion unit via a pipeline.

[0014] Furthermore, the CO2 capture unit includes a CO2 compression and purification device and a CO2 storage tank connected by a pipeline. A preheater is provided in the flue of the fuel reactor, and the CO2 storage tank is connected to the preheater by a pipeline.

[0015] This invention provides a method for generating electricity using the above-described chemical loop combustion power generation system, comprising the following steps: S1. Start the air reactor and fuel reactor to burn the fuel; S2. The high-temperature steam generated by the chemical loop combustion unit enters the power generation unit to power the turbine for startup and operation, thereby generating electricity. S3. The exhaust gas discharged from the air reactor enters the first exhaust gas dust collector through a pipeline for dust removal. After dust removal, it enters the main flue of the power generation unit and is treated synchronously with the flue gas in the main flue through the flue gas treatment system. At the same time, the exhaust gas discharged from the fuel reactor enters the second exhaust gas dust collector through a pipeline for dust removal. After dust removal, it enters the exhaust gas desulfurization device for desulfurization. The desulfurized flue gas enters the CO2 capture unit to achieve high-purity CO2 capture. The CO2 in the S4.CO2 capture unit is preheated and then fed into the fuel reactor as feed air.

[0016] Furthermore, in step S2, the drainage from the turbine during operation enters the chemical loop combustion unit through a pipeline for water replenishment.

[0017] In summary, compared with the prior art, the present invention has the following advantages: The technical solution of this invention realizes the practical operation of chemical loop combustion technology in power plants by sending the high-temperature steam generated by the chemical loop combustion unit into the steam turbine of the power generation unit; by separating and purifying the exhaust gases of the air reactor and the fuel reactor, the cost of exhaust gases is reduced; the exhaust gas from the air reactor is connected to the flue gas treatment system of the power generation unit after dust removal by the first exhaust gas dust collector, and the exhaust gas achieves emission standards through the flue gas treatment system; the exhaust gas generated by the fuel reactor contains high concentrations of carbon dioxide, which is directly entered into the CO2 capture unit after dust removal and desulfurization, achieving efficient carbon dioxide capture. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the chemical looping combustion power generation system in Embodiment 1 of the present invention.

[0020] Explanation of reference numerals in the attached drawings: 1-Power generation unit; 101-Boiler; 102-Air preheater; 103-Dust collector; 104-Desulfurization tower; 105-Chimney; 106-Steam turbine; 2-Feeding unit; 3-Chemical loop combustion unit; 301-Air reactor; 302-Fuel reactor; 4-Tail gas purification unit; 401-First tail gas dust collector; 402-Second tail gas dust collector; 403-Tail gas desulfurization device; 5-CO2 capture unit; 501-CO2 compression and purification device; 502-CO2 storage tank. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Example 1 A chemical loop combustion power generation system, with a system scale of 20MW-300MW, such as Figure 1 As shown, it includes a power generation unit 1, a feeding unit 2, a chemical looping combustion unit 3, an exhaust gas treatment unit 4, and a CO2 capture unit 5, as detailed below: Power generation unit 1 includes a boiler 101, an air preheater 102, a flue gas treatment system, and a steam turbine 106 connected in sequence via pipelines to the steam outlet of the boiler 101 (the connection between the boiler and the steam turbine is a conventional technique in this field, therefore...). Figure 1(The connection between the two is not shown in the diagram). The flue gas treatment system includes a dust collector 103, a desulfurization tower 104, and a chimney 105 connected in sequence via pipelines. The steam turbine 106 includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder. The high-temperature steam in the boiler 101 is heated in the high-temperature reheater after being heated by the high-pressure cylinder, and then drives the generator to generate electricity by being heated by the intermediate-pressure cylinder and the low-pressure cylinder in sequence. At the same time, the high-temperature reheater is also connected to the high-temperature steam outlet of the chemical loop combustion unit 3, using the high-temperature steam generated by the chemical loop combustion unit 3 to power the steam turbine 106 for startup and operation, thereby generating electricity. The drain outlet of the steam turbine 106 is connected to the chemical loop combustion unit 3 via a pipeline for replenishing water to the chemical loop combustion unit 3.

[0025] The feeding unit 2 includes an oxygen carrier feeding module and a fuel feeding module. The fuel feeding module uses solid fuel as the reaction fuel for the chemical looping combustion unit 3. It can use solid fuel with a particle size of less than 4 mm, or a mixture of coal and biomass or coal and sludge. The fuel reacts with oxygen in the oxygen carrier in the fuel reactor 302 of the chemical looping combustion unit 3 to generate heat.

[0026] The chemical looping combustion unit 3 includes an air reactor 301 and a fuel reactor 302. The air reactor 301 is used for the oxidation and regeneration of the oxygen carrier and to generate high-temperature flue gas. The fuel reactor 302 is used for the reaction of solid fuel with the reduced oxygen carrier to generate a mixture containing carbon dioxide. The solid fuel reacts with oxygen in the oxygen carrier in the fuel reactor 302 of the chemical looping combustion unit 3 to generate heat. The high-temperature steam generated by the chemical looping combustion unit 3 has a temperature of 520℃-630℃ and a pressure ≥9.2MPa.

[0027] The exhaust gas treatment unit 4 includes a first exhaust gas dust collector 401, a second exhaust gas dust collector 402, and an exhaust gas desulfurization device 403. The inlet of the first exhaust gas dust collector 401 is connected to the exhaust gas outlet of the air reactor 301 via a pipe, performing dust removal treatment on the exhaust gas from the air reactor 301. The outlet of the first exhaust gas dust collector 401 is connected to the main flue of the power generation unit 1 via a pipe, and enters the flue gas treatment system synchronously with the flue gas from the main flue for treatment. The inlet of the second exhaust gas dust collector 402 is connected to the fuel reactor 302 via a pipe, performing dust removal treatment on the exhaust gas generated by the fuel reactor 302. The outlet of the second exhaust gas dust collector 402 is connected to the exhaust gas desulfurization device 403 via a pipe, performing desulfurization treatment on the dust-removed exhaust gas.

[0028] The CO2 capture unit 5 includes a CO2 compression and purification device 501 and a CO2 storage tank 502 connected by pipelines. The inlet of the CO2 compression and purification device 501 is connected to the outlet of the tail gas desulfurization device 403 via a pipeline, and the outlet of the CO2 compression and purification device 501 is connected to the inlet of the CO2 storage tank 502 via a pipeline. The CO2 compression and purification device 501 has CO2 cooling and CO2 compression and purification functions. The CO2 cooling adopts one or more of water cooling, mechanical refrigeration, and absorption refrigeration, and the CO2 capture efficiency is ≥92%. A preheater is provided in the flue of the fuel reactor 302. The outlet of the CO2 storage tank 502 is connected to the preheater via a pipeline. After the captured CO2 is preheated, it is used as feed air to transport the oxygen carrier and solid fuel to the fuel reactor 302 respectively. To ensure that no air is introduced into the fuel reactor 302 of the chemical loop combustion unit 3, high-purity CO2 produced by the CO2 compression and purification device 501 in the CO2 capture unit 5 is used as feed air during the process of replenishing solid fuel and oxygen carrier to the fuel reactor 302. A CO2 preheater is installed in the flue of the fuel reactor 302 to preheat the CO2 before carrying the solid fuel into the fuel reactor 302, so as to avoid lowering the temperature in the reactor.

[0029] The specific steps for generating electricity using the above-mentioned chemical looping combustion power generation system are as follows: S1. The feeding unit 2 uses coal as solid fuel. After the chemical loop combustion unit 3 is started by injecting fuel oil, the air reactor 301 and the fuel reactor 302 operate to burn the fuel. S2. The 620°C high-temperature steam generated by the chemical loop combustion unit 3 enters the high-temperature reheater of the 1000MW power generation unit 1 of the coal-fired power plant to start and run the steam turbine 106, enabling the steam turbine 106 to generate electricity. At the same time, the drainage from the steam turbine 106 during operation enters the chemical loop combustion unit 3 for makeup water. S3. The exhaust gas discharged from the air reactor 301 enters the first exhaust gas dust collector 401 through a pipeline for dust removal. After dust removal, it enters the main flue of the power generation unit 1 and is treated synchronously with the flue gas in the main flue through the flue gas treatment system. The exhaust gas discharged from the fuel reactor 302 enters the second exhaust gas dust collector 402 through a pipeline for dust removal. After dust removal, it enters the exhaust gas desulfurization device 403 for exhaust gas desulfurization. The desulfurized flue gas enters the CO2 storage tank 502 through the CO2 compression and purification device 501, with a CO2 capture efficiency of 93.5%. The CO2 in the S4.CO2 storage tank 502 is preheated and then used as feed air to enter the fuel reactor 302.

[0030] Example 2 A chemical looping combustion power generation method, using the chemical looping combustion power generation system in Example 1, comprises the following specific steps: S1. The feeding unit 2 uses biomass as fuel. After the chemical loop combustion unit 3 is started by injecting fuel oil, the air reactor 301 and the fuel reactor 302 operate to burn the fuel. S2. The 530°C high-temperature steam generated by the chemical loop combustion unit 3 enters the high-temperature reheater of the 1000MW power generation unit 1 of the coal-fired power plant to start and run the steam turbine 106, enabling the steam turbine 106 to generate electricity. At the same time, the drainage from the steam turbine 106 during operation enters the chemical loop combustion unit 3 for water replenishment. S3. The exhaust gas discharged from the air reactor 301 enters the first exhaust gas dust collector 401 through a pipeline for dust removal. After dust removal, it enters the main flue of the power generation unit 1 and is treated synchronously with the flue gas in the main flue through the flue gas treatment system. The exhaust gas discharged from the fuel reactor 302 enters the second exhaust gas dust collector 402 through a pipeline for dust removal. After dust removal, it enters the exhaust gas desulfurization device 403 for exhaust gas desulfurization. The desulfurized flue gas enters the CO2 storage tank 502 through the CO2 compression and purification device 501, with a CO2 capture efficiency of 94%. The CO2 in the S4.CO2 storage tank 502 is preheated and then used as feed air to enter the fuel reactor 302.

[0031] Example 3 A chemical looping combustion power generation method, using the chemical looping combustion power generation system in Example 1, comprises the following specific steps: S1. The feeding unit 2 uses a mixture of coal and biomass as fuel, with a biomass co-combustion rate of 3%. After the chemical loop combustion unit 3 is started by injecting fuel oil, the air reactor 301 and the fuel reactor 302 operate to burn the fuel. S2. The 570°C high-temperature steam generated by the chemical loop combustion unit 3 enters the high-temperature reheater of the 1000MW power generation unit 1 of the coal-fired power plant to power the turbine 106 for startup and operation, thereby enabling the turbine 106 to generate electricity; the wastewater from the turbine 106 during operation enters the chemical loop combustion unit 3 for makeup water. S3. The exhaust gas discharged from the air reactor 301 enters the first exhaust gas dust collector 401 through a pipeline for dust removal. After dust removal, it enters the main flue of the power generation unit 1 and is treated synchronously with the flue gas in the main flue through the flue gas treatment system. The exhaust gas discharged from the fuel reactor 302 enters the second exhaust gas dust collector 402 through a pipeline for dust removal. After dust removal, it enters the exhaust gas desulfurization device 403 for exhaust gas desulfurization. The desulfurized flue gas enters the CO2 storage tank 502 through the CO2 compression and purification device 501, with a CO2 capture efficiency of 92%. The CO2 in the S4.CO2 storage tank 502 is preheated and then used as feed air to enter the fuel reactor 302.

[0032] The chemical loop combustion power generation system provided by this invention has the following beneficial effects: First, by coupling the chemical looping combustion system with the main power generation system in a coal-fired power plant, the engineering application of chemical looping combustion technology in power plant power generation has been truly realized. On the other hand, it reduces the carbon emissions of the power plant, achieves efficient capture and purification of carbon dioxide, and brings benefits to the power plant through further resource utilization of carbon dioxide.

[0033] Second, using solid fuels as reaction fuels in chemical loop combustion units reduces the process flow of chemical loop combustion power generation systems and lowers safety risks. Using mixed solid fuels such as coal + biomass and coal + sludge can reduce system coal consumption, while realizing the utilization and disposal of biomass and sludge, further reducing carbon emissions, and realizing the ability of chemical loop combustion systems to co-process solid waste.

[0034] Third, the system has achieved waste heat utilization, reduced energy consumption of the power generation system, low-carbon operation, and reduced operating costs.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chemical looping combustion power generation system, characterized in that, It includes a feeding unit (2) and a tail gas purification unit (4). The feeding unit (2) is connected to a chemical loop combustion unit (3). The chemical loop combustion unit (3) includes an air reactor (301) and a fuel reactor (302). The high-temperature steam outlet of the chemical loop combustion unit (3) is connected to the steam turbine (106) of the power generation unit (1) through a pipeline. The tail gas purification unit (4) includes a first tail gas dust collector (401), a second tail gas dust collector (402), and a tail gas desulfurization device (403). The exhaust outlet of the air reactor (301) is connected to the first exhaust gas dust collector (401) via a pipe, and the outlet of the first exhaust gas dust collector (401) is connected to the flue gas treatment system in the power generation unit (1) via a pipe; the exhaust outlet of the fuel reactor (302) is connected to the second exhaust gas dust collector (402) via a pipe, and the outlet of the second exhaust gas dust collector (402) is connected to the exhaust gas desulfurization device (403) via a pipe, and the exhaust gas desulfurization device (403) is connected to the CO2 capture unit (5) via a pipe.

2. The chemical looping combustion power generation system according to claim 1, characterized in that, The power generation unit (1) includes a boiler (101), an air preheater (102), a flue gas treatment system, and a steam turbine (106) connected in sequence via pipes. The flue gas treatment system includes a dust collector (103), a desulfurization tower (104), and a chimney (105) connected in sequence via pipes.

3. The chemical looping combustion power generation system according to claim 1, characterized in that, The power generation unit (1) also includes a high-temperature reheater connected to the steam turbine (106), and the high-temperature steam outlet of the chemical loop combustion unit (3) is connected to the high-temperature reheater via a pipeline.

4. The chemical looping combustion power generation system according to claim 1, characterized in that, The drain outlet of the steam turbine (106) is connected to the chemical loop combustion unit (3) via a pipe.

5. The chemical looping combustion power generation system according to claim 1, characterized in that, The high-temperature steam generated by the chemical loop combustion unit (3) has a temperature of 520℃-630℃ and a pressure of ≥9.2MPa.

6. The chemical looping combustion power generation system according to claim 1, characterized in that, The feeding unit (2) includes an oxygen carrier feeding module and a fuel feeding module. The fuel feeding module uses solid fuel, including at least one of coal or its co-fired biomass and sludge. The particle size of the solid fuel is ≤5mm.

7. The chemical looping combustion power generation system according to claim 1, characterized in that, The carbon dioxide outlet of the CO2 capture unit (5) is connected to the chemical chain combustion unit (3) via a pipe.

8. The chemical looping combustion power generation system according to claim 7, characterized in that, The CO2 capture unit (5) includes a CO2 compression and purification device (501) and a CO2 storage tank (502) connected by a pipeline. A preheater is provided in the flue of the fuel reactor (302), and the CO2 storage tank (502) is connected to the preheater by a pipeline.

9. A method for generating electricity using the chemical looping combustion power generation system according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Start the air reactor (301) and fuel reactor (302) to burn the fuel; S2. The high-temperature steam generated by the chemical loop combustion unit (3) enters the power generation unit (1) to power the steam turbine (106) for startup and operation, thereby enabling the steam turbine (106) to generate electricity. S3. The exhaust gas discharged from the air reactor (301) enters the first exhaust gas dust collector (401) through a pipeline for dust removal. After dust removal, it enters the main flue of the power generation unit (1) and is treated synchronously with the flue gas in the main flue through the flue gas treatment system. At the same time, the exhaust gas discharged from the fuel reactor (302) enters the second exhaust gas dust collector (402) through a pipeline for dust removal. After dust removal, it enters the exhaust gas desulfurization device (403) for desulfurization. The desulfurized flue gas enters the CO2 capture unit (5) to achieve high-purity CO2 capture. The CO2 in the S4.CO2 capture unit (5) is preheated and then used as feed air to enter the fuel reactor (302).

10. The method according to claim 9, characterized in that, In step S2, the drainage from the turbine (106) during operation enters the chemical loop combustion unit (3) through a pipeline for water replenishment.

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