High-temperature carbon capture and in-situ conversion and utilization system and method for gas-steam combined cycle power generation coupled with electrolytic water

Abstract

The present invention provides a high-temperature carbon capture and in-situ conversion and utilization system and method for gas-steam combined cycle power generation coupled with electrolytic water, including a combined cycle power generation unit subsystem, a carbon capture and in-situ conversion subsystem, and an electrolytic water subsystem. The carbon capture and in-situ conversion subsystem captures carbon from the high-temperature carbon-containing flue gas discharged by the gas turbine power generation unit of the combined cycle power generation unit subsystem and conducts in-situ conversion to obtain target chemical products. The high-temperature decarbonized flue gas and product gas respectively return to the waste heat boiler to drive the steam turbine power generation unit to generate electricity; the hydrogen required for the carbon conversion process is provided by the electrolytic water system; the electric energy of the electrolytic water subsystem is utilized with the valley electricity or green electricity of the power plant, and the oxygen generated by electrolyzing water provides an oxygen-enriched combustion atmosphere for the gas turbine power generation unit. The present invention couples the high-temperature carbon capture and in-situ conversion system with electrolytic water and the gas-steam combined cycle power generation unit for process coupling and energy integration. Through the full-process energy coupling and optimization, it is expected to achieve a disruptive negative carbon technology on the premise of maintaining the existing power generation efficiency of the power plant.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture, conversion and utilization, and relates to high-temperature carbon dioxide capture and in-situ conversion and utilization. Specifically, it relates to a high-temperature carbon capture and in-situ conversion and utilization system and method for a gas-steam combined cycle power generation coupled with electrolytic water. Background Art

[0002] Electric power is the largest source of carbon emissions in the energy industry, accounting for nearly 40% of the global energy-related carbon emissions. Given the characteristics of China's energy structure, the power industry will still be dominated by fossil fuel-fired power generation. Therefore, carbon capture, utilization and storage (CCUS) technology will become one of the important means indispensable for promoting the low-carbon utilization of fossil energy in the power industry. In gas-steam combined cycle technology for thermal power generation, the energy utilization and power generation efficiency are greatly improved through the cascade utilization of energy, and it is considered a future clean and efficient comprehensive utilization technology of fossil fuels. This technology mainly uses gas turbines, waste heat boilers and steam turbines as main equipment. The gas turbine ignites and heats to drive the gas turbine to rotate. The high-temperature flue gas (550°C - 610°C) enters the waste heat boiler through the diffuser section of the gas turbine, heats the boiler feed water to generate high-temperature and high-pressure steam to drive the steam turbine, further improving the thermal efficiency. The flue gas (about 90°C) after heat exchange in the waste heat boiler is discharged into the atmosphere. Due to the large volume of flue gas treatment and the low partial pressure of carbon dioxide (CO 2 ), the energy consumption and capture cost of the separation process increase significantly.

[0003] Existing large-scale CO 2 capture technologies for thermal power generation mainly adopt the solvent absorption method. The high-temperature flue gas must be cooled to a low temperature (<50°C) before it can be absorbed, resulting in large heat losses. Coupled with the high cost of the solvent and high regeneration energy consumption, the additional energy consumption of coal-fired power plants increases (the power supply efficiency is reduced by 10 - 15%). Secondly, the outlet problem of the captured CO 2 , and the high costs caused by its supporting CO 2 compression, transportation, etc. also restrict the large-scale adoption of CCUS in thermal power plants to achieve carbon neutrality.

[0004] The high-value utilization of CO 2 is a way to achieve artificial carbon cycling, and at the same time can offset part of the capture cost and generate certain economic benefits. However, since CO 2 is extremely stable thermodynamically, a large amount of hydrogen source and additional energy input (high-temperature conditions) are required to convert it into high-value-added chemicals (such as methane and syngas, etc.), making the large-scale CO 2 resource utilization also face problems of high cost and high energy consumption. Due to the temperature mismatch between traditional low-temperature carbon capture and high-temperature carbon conversion processes, how to couple the carbon capture process and carbon conversion has become a key issue in CCUS.

[0005] Based on the thermal energy of the high-temperature flue gas emitted by the gas turbine of the combined cycle power generation unit, the off-peak electricity of the power plant, and the large-scale electrolysis of water to provide high-purity green hydrogen, it is of great significance to study a low-cost and low-energy consumption coupling electrolysis of water high-temperature carbon capture and in-situ conversion technology and the integration technology of the gas-steam combined cycle unit. The research and development of this technology can eliminate CO from the source. 2 The production of flue gas heat energy is used to realize artificial carbon cycle, reducing the high energy consumption required by CCUS, and converting CO 2 Transform it into value-added products to solve the bottleneck problem of low-carbon development in the power industry. Summary of the invention

[0006] The present invention is aimed at the gas-steam combined cycle power generation system. The high-temperature flue gas (550-650℃) discharged from the gas turbine is passed into the waste heat boiler to drive the steam turbine to generate electricity, and finally the CO in the carbon-containing flue gas (90-110℃) is discharged. 2 To solve the problem of low concentration being difficult to handle, a system and method for high-temperature carbon capture and in-situ conversion and utilization coupled with water electrolysis is provided, which establishes a new model of low-carbon power generation in power plants from the production source.

[0007] The high-temperature flue gas discharged by the gas turbine is carbon captured, and the captured carbon is converted in situ as a resource to obtain the target chemical products, forming an artificial chemical carbon cycle; or providing raw materials for the chemical industry to achieve coordinated carbon neutrality among industries. The hydrogen required for the carbon conversion process is provided by the water electrolysis system. The electrolysis process uses valley electricity or green electricity from the power plant as a power source to improve the peak-shaving capacity of the power plant. The oxygen produced by water electrolysis can provide an oxygen-rich combustion atmosphere for the gas turbine. Therefore, the high-temperature carbon capture and in-situ conversion system coupled with water electrolysis is coupled with the gas-steam combined cycle power generation unit for process coupling and energy integration. Through full-process energy coupling and optimization, it is expected to achieve disruptive negative carbon technology while maintaining the existing power generation efficiency of the power plant.

[0008] The first aspect of the present invention provides a high-temperature carbon capture and in-situ conversion utilization system for gas-steam combined cycle power generation coupled with water electrolysis, which has the following technical features: it includes a combined cycle power generation unit subsystem, a carbon capture and in-situ conversion subsystem and a water electrolysis subsystem.

[0009] The combined cycle power generation unit subsystem includes a gas turbine power generation unit and a steam turbine power generation unit: the gas turbine power generation unit includes a compressor, a combustion chamber, a gas turbine, a gas turbine generator and a heat exchanger; the steam turbine power generation unit includes a waste heat boiler, a steam turbine, a steam turbine generator, a condenser, a gas transportation unit and a circulating pump.

[0010] In a gas turbine power generation unit, a compressor, a combustion chamber, and a gas turbine are connected in sequence to form a Brayton cycle unit, which drives a gas turbine generator to generate electricity; a waste heat boiler, a steam turbine, a condenser, and a circulating pump are connected in sequence to form a Rankine cycle unit, which drives a steam turbine generator to generate electricity.

[0011] The carbon capture and in-situ conversion subsystem is embedded between the Brayton cycle unit and the Rankine cycle unit, that is, between the gas turbine outlet of the gas turbine power generation unit and the waste heat boiler inlet of the steam turbine power generation unit, and includes an intake control unit, an adsorption and conversion reaction tower, a detection and control system, a water vapor separator, and a gas transmission unit.

[0012] The intake control unit includes a flue gas, hydrogen, and nitrogen intake program control device; there are at least two adsorption and conversion reaction towers arranged in parallel, including a reactor and an internal heat exchange unit. The reactor is a fixed bed, fluidized bed, or moving bed, and is provided with an adsorption / catalytic bifunctional material. By switching between high-temperature flue gas and hydrogen, continuous operation of CO 2 capture and in-situ conversion is achieved; the detection and control system includes various sensors, instruments, controllers, etc., which monitor various parameters in real time and control the reaction process within the normal range; the water vapor separator includes a condenser that condenses the gas into water; the gas transmission unit includes pipelines and various valves installed on the pipelines.

[0013] The water electrolysis subsystem includes a water electrolysis cell, an oxygen storage tank, and a hydrogen storage tank respectively connected to the anode and cathode of the electrolysis cell; the oxygen storage tank is connected to the compressor through a valve, and the hydrogen storage tank is connected to the adsorption and conversion reaction tower through a valve.

[0014] In the second aspect of the present invention, a method for high-temperature carbon capture and in-situ conversion and utilization using the above system is provided, which is characterized by including the following steps:

[0015] (1) In the carbon capture and in-situ conversion subsystem, the high-temperature carbon-containing flue gas generated by the gas turbine of the combined cycle power generation unit subsystem, CO 2 is adsorbed by the adsorption / catalytic bifunctional material and is in-situ catalytically hydrogenated to a target chemical product with the participation of hydrogen generated by the water electrolysis subsystem;

[0016] (2) The high-temperature decarbonized flue gas and high-temperature product gas generated in step (1) respectively undergo heat exchange in the waste heat boiler to drive the steam turbine generator to generate electricity; the low-temperature decarbonized flue gas after heat exchange is directly discharged, the low-temperature target chemical product is stored as a chemical production raw material or used as fuel for gas power generation, and the condensed water provides water source for the water electrolysis subsystem;

[0017] (3) The combined cycle power generation unit subsystem provides electrical energy for the water electrolysis subsystem, and the oxygen generated by electrolysis provides an oxygen-rich environment for the fuel combustion in the combustion chamber of the combined cycle power generation unit subsystem.

[0018] Preferably, step (1) specifically includes the following steps:

[0019] According to the reaction temperature required for the carbon capture and in-situ conversion process, the high-temperature carbon-containing flue gas is cooled by heat exchange in a heat exchanger or directly enters the adsorption and conversion reaction tower, and CO 2 is adsorbed and captured by the adsorption / catalytic bifunctional material, and the reaction temperature is controlled during the capture process; after the current reaction tower is saturated with adsorption, it is switched to other parallel reaction towers to continue carbon capture. At the same time, after purging the current reaction tower with nitrogen, preheated hydrogen is introduced to catalytically convert the adsorbed CO 2 in-situ to obtain the target chemical product, and the parallel reaction towers are sequentially subjected to adsorption, purging, and in-situ hydrogenation conversion.

[0020] Among them, the adsorption / catalytic bifunctional material used in the carbon capture and in-situ conversion subsystem has an adsorption active component of alkali metal oxide and a catalytic active component of a bimetallic catalyst.

[0021] The high-temperature carbon capture technology is mainly based on the cycle of carbonation and decarbonation occurring between alkali metal oxides, alkaline earth metal oxides, and their carbonates, as shown in Equations 1-4. The main alkali metals are calcium-based adsorbents and magnesium-based adsorbents.

[0022] CaO + CO 2 = CaCO 3 , ΔH 298K = -178 kJ / mol (1)

[0023] MgO + CO 2 = MgCO 3 , ΔH 298K = -101 kJ / mol (2)

[0024] Na 2 O + CO 2 = Na 2 CO3 ΔH 298K = -322 kJ / mol (3)

[0025] K 2 O + CO 2 = K 2 CO 3 ΔH 298K = -348 kJ / mol (4)

[0026] The method of controlling the reaction temperature during the capture process is as follows: for exothermic reactions, heat needs to be exported through the heat exchange unit inside the adsorption and conversion reaction tower; for endothermic reactions, high-temperature flue gas at 900 - 1100 °C generated after the fuel gas passes through a combustion heater is introduced into the jacket of the adsorption and conversion reaction tower to supplement heat for the carbon conversion reaction.

[0027] In-situ CO 2 The reactions mainly involved in catalytic hydrogenation reduction are the reverse water-gas shift reaction (RWGS), methanation reaction, hydrogenation to methanol, hydrogenation to olefins, etc. (as shown in Equations 5-7).

[0028] CO 2 +H 2 = CO + H 2 O, ΔH 298K = +41 kJ / mol (5)

[0029] CO 2 + 4H 2 = CH 4 + 2H 2 O ΔH 298K = -63 kJ / mol (6)

[0030] CO 2 + H 2 = CH 3 OH + H 2 O ΔH 298K = -49.5 kJ / mol (7)

[0031] nCO 2 + (3n + 1)H 2 = C n H 2n+1 + 2nH 2 O ΔH 298K = -128 kJ / mol (8)

[0032] In-situ CO 2 The main catalysts for catalytic hydrogenation reduction are nickel-based bimetals, iron-based bimetals, copper-based bimetals, noble metal catalysts such as platinum, ruthenium, rhodium, zirconium, etc.

[0033] In-situ CO 2 The target products of catalytic hydrogenation conversion can be but are not limited to methane, syngas, lower alcohols, olefins, light fuels, etc.

[0034] Preferably, step (2) includes the following steps:

[0035] The high-temperature decarbonized flue gas and high-temperature product gas generated in the adsorption and conversion reaction tower are respectively passed into the waste heat boiler for heat exchange to transfer heat to steam, driving the steam turbine generator set to generate electricity; the low-temperature decarbonized flue gas is directly discharged, while the low-temperature product gas enters the storage tank after dehydration by the water-gas separator. Among them, the product gas that can be used as fuel for gas power generation is passed into the combustion chamber for combustion utilization to form an artificial carbon cycle, and other products are used for high-value-added chemical utilization; the water generated by the water-gas separator is passed into the electrolytic cell through a circulation pump for electrolysis.

[0036] Step (3) includes the following steps:

[0037] Utilize the redundant valley electricity or green electricity after peak shaving by the combined cycle power generation system to input into the electrolyzer for water electrolysis, generating oxygen and hydrogen, which are respectively transported to the oxygen storage tank and the hydrogen storage tank through pipelines; the oxygen in the oxygen storage tank is mixed with air, compressed by a compressor, and then fed into the combustion chamber together with the fuel for oxygen-enriched combustion to drive the gas turbine generator to generate electricity.

[0038] Beneficial guarantees and effects of the present invention:

[0039] 1. The carbon capture and in-situ conversion and utilization system for gas-steam combined cycle power generation coupled with water electrolysis provided by the present invention is based on a combined cycle power generation unit, integrating the originally independent combined cycle power generation system, carbon capture process, carbon conversion and utilization system, and water electrolysis system into an organic whole, realizing efficient energy utilization and recycling of raw materials, and achieving low-energy-consumption high-temperature flue gas CO 2 capture and high-value utilization while maintaining the existing power generation efficiency of the power plant.

[0040] 2. Compared with the carbon capture process of traditional thermal power plants, the method of the present invention makes full use of the heat of the high-temperature flue gas discharged from the gas turbine unit in combined cycle power generation and the reaction heat of the adsorption process, directly in-situ converting the captured CO 2 , realizing efficient energy utilization, and avoiding the contradiction that the normal-temperature CO 2 capture requires cooling the high-temperature flue gas and the reaction conversion process requires heating up, greatly reducing energy consumption and realizing the energy utilization of high-temperature flue gas.

[0041] 3. The method provided by the present invention realizes the in-situ hydrogenation conversion of the captured CO 2 into value-added products. The carbon capture and conversion processes are carried out in the same reactor, avoiding processes such as gas compression and pipeline transportation. The process is relatively simple, reducing equipment investment. At the same time, the chemical products produced can directly enter the gas turbine unit as fuel or as raw materials for downstream chemical production, generating certain economic value and realizing artificial carbon cycling, thereby reducing the use of fossil fuels.

[0042] 4. The present invention provides electric energy for hydrogen production by water electrolysis by utilizing the valley electricity or green electricity of combined cycle power generation, enhancing the peak shaving ability of the power plant. Water electrolysis provides a hydrogen source for the in-situ conversion of CO 2 , and at the same time, the generated oxygen replaces part of the air introduced into the gas turbine, increasing the oxygen content in the gas turbine unit, which is beneficial to improving the combustion efficiency of the gas turbine. At the same time, the water generated during the in-situ conversion hydrogenation process can be sent back to the water electrolysis subsystem as raw materials to realize the recycling of water. Description of the Drawings

[0043] Figure 1It is a process flow block diagram of the carbon capture and in-situ conversion technology that couples gas-steam combined cycle power generation with electrolyzed water in the present invention.

[0044] Figure 2 It is a schematic process flow diagram of the high-temperature carbon capture and in-situ conversion of methane system that couples gas-steam combined cycle power generation with electrolyzed water.

[0045] Among them, combustion chamber F-1; waste heat boiler F-2; air compressor C-1; gas turbine M-1; steam turbine M-2; electrolytic cell M-3; heat exchangers E-1, E-3; condensers E-2, E-4; circulation pumps P-1, P-2; methane storage tank S-1; hydrogen storage tank S-2; oxygen storage tank S-3; adsorption and conversion reaction towers T-1, T-2; two-way valves V-1~2, V-9~12; three-way valves V-3~V-7; four-way valve V-8.

[0046] Figure 3 It is a schematic process flow diagram of the high-temperature carbon capture and in-situ conversion of syngas system that couples gas-steam combined cycle power generation with electrolyzed water.

[0047] Among them, combustion chamber F-1; waste heat boiler F-2; combustion heater F-3; air compressor C-1; gas turbine M-1; steam turbine M-2; electrolytic cell M-3; heat exchangers E-1, E-3; condensers E-2, E-4; circulation pumps P-1, P-2; syngas storage tank S-1; hydrogen storage tank S-2; oxygen storage tank S-3; adsorption and conversion reaction towers T-1, T-2; two-way valves V-1, V-3, V-7, V-11, V-13~15; three-way valves V-2, V-4, V-5~6, V-8~9, V-12; four-way valve V-10. Specific embodiments

[0048] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0049] According to Figure 1 , the high-temperature carbon capture and in-situ conversion system 100 that couples electrolyzed water based on a gas-steam combined cycle power generation unit includes: a combined cycle power generation unit subsystem 1, a carbon capture and in-situ conversion subsystem 2, and an electrolyzed water subsystem 3.

[0050] Combined with Figure 1 and Figure 3 , the combined cycle power generation unit subsystem 1 includes a gas turbine power generation unit and a steam turbine power generation unit: the gas turbine power generation unit includes a compressor, a combustion chamber, a gas turbine, a gas turbine generator, and a heat exchanger; the steam turbine power generation unit includes a waste heat boiler, a steam turbine, a steam turbine generator, a condenser, a gas transportation unit, and a circulation pump.

[0051] Fuel and oxygen enter a gas turbine, are compressed and burned to generate electricity. The high-temperature flue gas generated is output from the gas turbine. After high-temperature adsorption and conversion in the carbon capture and in-situ conversion subsystem 2, the obtained high-temperature flue gas and product gas enter a waste heat boiler to heat steam, driving a steam turbine generator to generate electricity. The low-temperature decarbonized flue gas after heat exchange is directly discharged. Light fuels such as methane in the low-temperature product gas return to the combustion chamber in the gas power generation unit for combustion. Syngas, lower alcohols, olefins, etc. enter a gas storage tank for chemical applications. The oxygen generated by the electrolyzed water subsystem 3 enters an air compressor, providing an oxygen-rich environment to improve the efficiency of the gas turbine.

[0052] For the carbon capture and in-situ conversion subsystem 2, it includes an intake control unit, an adsorption and conversion reaction tower, a detection and control system, a water vapor separator, and a gas transmission unit.

[0053] The intake control unit includes a flue gas, hydrogen, and nitrogen intake program control device; there are at least two adsorption and conversion reaction towers arranged in parallel, including a reactor and an internal heat exchange unit. The reactor is a fixed bed, fluidized bed, or moving bed, and is internally provided with an adsorption / catalytic bifunctional material. By switching between high-temperature flue gas and hydrogen, continuous operation of CO 2 capture and in-situ conversion is achieved; the detection and control system includes various sensors, instruments, controllers, etc., real-time monitoring various parameters, and controlling the reaction process within the normal range; the water vapor separator includes a condenser to condense the gas into water; the gas transmission unit includes pipelines and various valves installed on the pipelines.

[0054] The high-temperature flue gas output from the gas turbine of the combined cycle power generation unit subsystem 1, the hydrogen output from the hydrogen storage tank of the electrolyzed water subsystem 3, and the nitrogen output from the nitrogen storage tank respectively enter the intake control unit, and after heat exchange in a preheater, enter the adsorption and conversion reaction tower in sequence; the obtained high-temperature decarbonized flue gas and high-temperature product gas are output from the adsorption and conversion reaction tower and enter the waste heat boiler of the combined cycle power generation unit subsystem 1 for heat exchange.

[0055] For the electrolyzed water subsystem 3, it includes an electrolyzed water cell, and an oxygen storage tank and a hydrogen storage tank respectively connected to the anode and cathode of the electrolyzed cell; the oxygen storage tank is connected to a compressor through a valve, and the hydrogen storage tank is connected to the adsorption and conversion reaction tower through a valve.

[0056] The redundant electric energy after peak shaving of the combined cycle power generation subsystem 1 provides electric energy for the electrolyzed cell. The oxygen generated at the anode is output from the oxygen tank to the air compressor of the gas turbine of the combined cycle power generation unit subsystem 1, providing an oxygen-rich environment for fuel combustion. The hydrogen generated at the cathode is output from the hydrogen tank to the intake system of the carbon capture and in-situ conversion subsystem 2, and the captured CO 2 is in-situ hydrogenated to the target product. The water generated during the conversion process is condensed by the water vapor separator and enters the electrolyzed cell for electrolyzing water.

[0057] In-situ CO 2 The catalytic hydrogenation reduction mainly relies on reactions such as the reverse water-gas shift reaction (RWGS), methanation reaction, hydrogenation to methanol, and hydrogenation to olefins, etc. Taking the methanation reaction and the reverse water-gas shift reaction (RWGS) as examples respectively, the specific processes of the integration of high-temperature carbon capture coupled with electrolyzed water and in-situ conversion of methane and gas-steam combined cycle power generation are described in detail below. These two reactions also happen to be an exothermic reaction and an endothermic reaction respectively, and also show the temperature control methods during the reaction process.

[0058] Example 1 Integration of High-Temperature Carbon Capture Coupled with Electrolyzed Water and In-Situ Conversion of Methane and Gas-Steam Combined Cycle Power Generation Based on the Methanation Reaction

[0059] See Figure 2 . In this example, the high-temperature carbon capture and in-situ conversion of methane subsystem is coupled with the electrolyzed water subsystem, and then integrated with the gas-steam combined cycle power generation subsystem. First, the redundant electric energy after peak shaving by the combined cycle power generation subsystem is input into the electrolytic cell M-3 for water electrolysis. The generated oxygen and hydrogen are respectively transported to the oxygen storage tank S-3 and the hydrogen storage tank S-2 through pipelines. Open the two-way valve V-12, the oxygen in the oxygen storage tank S-3 is mixed with air, compressed by the compressor C-1, and then fed into the combustion chamber F-1 together with the fuel (methane) to generate high-temperature and high-pressure flue gas, which drives the gas turbine M-1 to do work and drives the gas turbine generator to generate electricity. The discharged high-temperature carbon-containing flue gas is about 600 °C.

[0060] Subsequently, open the two-way valve V-11. The high-temperature carbon-containing flue gas exchanges heat through the heat exchanger E-3, and the temperature is reduced to 400 °C, and then enters the carbon capture and conversion subsystem. The adsorption and conversion reaction towers T-1 and T-2 are filled with a magnesium-based adsorption / nickel-based bimetallic catalytic bifunctional material. Open the three-way valve V-7 and enter the adsorption and conversion reaction tower T-1 for carbon capture. The chemical reaction process occurring during the adsorption process is as shown in reaction equation 2. Since the adsorption process is exothermic, the heat is discharged in time through the heat exchange unit inside the reaction tower to control the temperature of the adsorption and conversion reaction tower between 350 - 450 °C. The temperature of the flue gas after decarbonization rises to 500 °C. When the adsorption and conversion reaction tower T-1 is saturated with adsorption, open the three-way valve V-7 to feed the high-temperature flue gas into the adsorption and conversion reaction tower T-2 for carbon capture. At the same time, open the two-way valve V-9, and purge the adsorption and conversion reaction tower T-1 with nitrogen for 5 minutes by controlling the four-way valve V-8. Subsequently, the four-way valve V-8 is switched to hydrogen. The hydrogen in the storage tank S-2 is preheated through the heat exchanger E-3 and then fed into the adsorption and conversion reaction tower T-1 to catalytically convert the adsorbed CO 2 to methane, and at the same time the adsorbent is regenerated. The CO 2The methanation reaction is an exothermic reaction as shown in Reaction Equation 6. Heat needs to be removed through the heat exchange unit inside the adsorption and conversion reaction tower, and the reactor temperature is controlled between 350 - 450 °C. After the conversion reaction is completed, it is ready to enter the next carbon capture stage. The two adsorption and conversion reaction towers T-1 and T-2 operate in parallel, and the switching of the carbon capture and carbon utilization processes is controlled by the three-way valve V-7 and the four-way valve V-8. The nitrogen purge during the switching from carbon capture to carbon conversion process is achieved by controlling the four-way valve V-8. Since the reactions occurring in the adsorption and reaction towers are all exothermic reactions, no additional heat needs to be supplemented during the carbon capture and in-situ conversion subsystem process. The heat of the high-temperature flue gas is used to preheat hydrogen, and at the same time, the exothermic reaction heat is fully utilized.

[0061] The high-temperature decarbonized flue gas (500 °C) and high-temperature product methane (450 °C) generated in the two adsorption and conversion reaction towers T-1 and T-2 can transfer heat to the waste heat boiler F-2 through the heat exchanger E-1 by adjusting the three-way valves V-3 - V-6. The steam generated by the waste heat boiler F-2 enters the steam turbine M-2 to do work and drives the turbogenerator to generate electricity, thereby improving the energy efficiency of the combined cycle power generation. Subsequently, the steam enters the condenser E-2 and turns into water, and then re-enters the waste heat boiler F-2 through the circulating pump P-1 for recycling. After passing through the heat exchanger E-1, the low-temperature decarbonized flue gas (90 °C) can be directly discharged through the two-way valve V-2, while the low-temperature methane (90 °C) can enter the methane storage tank S-1 after being separated and purified by the condenser E-4. Methane can be used as fuel gas and introduced into the combustion chamber F-1 through the two-way valve V-1 for combustion utilization, forming an artificial carbon cycle. The water generated by the condenser E-4 passes through the two-way valve V-10 and is electrolyzed in the electrolytic cell M-3 through the circulating pump P-2, achieving self-sufficiency of raw materials and energy.

[0062] Using the redundant valley electricity or green electricity of the power plant to electrolyze water, the hydrogen obtained at the cathode is used as the raw material for in-situ hydrogenation to prepare chemical products; moreover, at the same time, the oxygen generated at the anode can replace the air in the original combined cycle power generation system to provide an oxygen-rich environment for the fuel, improve the power generation efficiency of the gas turbine, and enhance the peak shaving capacity of the power plant. 2

[0063] Example 2 Integration of High-Temperature Carbon Capture and In-Situ Conversion of Syngas and Gas-Steam Combined Cycle Power Generation Based on the Reverse Water-Gas Shift (RWGS) Coupled with Electrolysis of Water

[0064] See Figure 3In this embodiment, the high-temperature carbon capture and in-situ syngas conversion subsystem is coupled with the electrolyzed water subsystem and then integrated with the gas-steam combined cycle power generation subsystem. First, the redundant electric energy after peak shaving by the combined cycle power generation subsystem is used to provide the energy for electrolyzing water in the electrolytic cell M-3 to generate oxygen and hydrogen, which are respectively stored in the hydrogen storage tank S-2 and the oxygen storage tank S-3. The two-way valve V-15 is opened, and the oxygen in the oxygen storage tank S-3 is mixed with air, compressed by the air compressor C-1, and then introduced into the combustion chamber F-1 together with the fuel (methane) to generate high-temperature and high-pressure flue gas, which drives the gas turbine M-1 to do work to drive the gas turbine generator to generate electricity, producing high-temperature carbon-containing flue gas at about 600 °C. Subsequently, the high-temperature carbon-containing flue gas enters the carbon capture and conversion subsystem through the two-way valve V-7.

[0065] The adsorption and conversion reaction towers T-1 and T-2 are filled with a calcium-based adsorption / iron-based bimetallic catalytic bifunctional material. The high-temperature carbon-containing flue gas enters the adsorption and conversion reaction tower T-1 through the three-way valve V-9 for the carbon capture process, and the adsorption process occurs as shown in reaction equation 1. Since the adsorption process is exothermic, the heat is discharged in a timely manner through the heat exchange unit inside the adsorption and conversion reaction tower during the adsorption process, and the temperature of the adsorption and conversion reaction tower is controlled at 600-650 °C. The decarbonized high-temperature flue gas is about 700 °C. After the adsorption and conversion reaction tower T-1 is saturated with adsorption, the three-way valve V-9 is controlled to introduce the high-temperature flue gas into the adsorption and conversion reaction tower T-2 for a new round of carbon capture process. At the same time, the two-way valve V-11 is opened, and nitrogen is introduced into the adsorption and conversion reaction tower T-1 through the four-way valve V-10 for purging for 5 minutes. Subsequently, the four-way valve V-10 is switched to hydrogen, and the hydrogen in the storage tank S-2 is preheated through the heat exchanger E-3 and then introduced into the adsorption and conversion reaction tower T-1 to desorb the adsorbed CO 2The catalytic conversion to CO, combined with the excess hydrogen to form synthesis gas, and the calcium-based adsorbent is regenerated. The chemical reaction in this process is shown in Reaction Equation 5. Since the reaction is an endothermic reaction, it is necessary to open the two-way valve V-13, and pass the fuel gas (methane) through the combustion heater F-3 to produce a high-temperature flue gas of about 900-1100°C, which is passed into the jacket of the adsorption and conversion reaction tower T-1 through the three-way valve V-12 to supplement the heat for the carbon conversion reaction, and the temperature of the reaction tower is controlled between 600-650°C. The temperature of the high-temperature flue gas after the heat supplement is maintained at 700°C, and then passes through the three-way valve V-8, and preheats the hydrogen through the heat exchanger E-3, heating the hydrogen to 600°C. The high-temperature flue gas after heat exchange is merged into the high-temperature carbon-containing flue gas generated by the gas turbine through the two-way valve V-3, and enters the carbon capture and utilization subsystem. After completing the conversion reaction, the reaction tower is ready to enter the next carbon capture stage. The two adsorption and conversion reaction towers T-1 and T-2 are operated in parallel, and the carbon capture, purge and conversion processes are switched by controlling the three-way valve V-9 and the four-way valve V-10. By controlling the three-way valve V-12, the high-temperature flue gas generated by the methane gas in the combustion heater F-3 is used to supplement the heat of the adsorption and conversion reaction tower T-1 or T-2 in the carbon utilization stage.

[0066] The high-temperature decarbonized flue gas (700℃) and high-temperature product synthesis gas (600℃) generated in the two adsorption and conversion reaction towers T-1 and T-2 can be adjusted by adjusting the three-way valves V-2 and V-4~6, and the heat can be transferred to the waste heat boiler F-2 through the heat exchanger E-1. The steam generated by the waste heat boiler F-2 enters the steam turbine M-2 to do work, driving the steam turbine generator to generate electricity, thereby improving the energy efficiency of the combined cycle power generation. The steam then enters the condenser E-2 to become water, and is re-introduced into the waste heat boiler F-2 for recycling through the circulating pump P-1. After passing through the heat exchanger E-1, the low-temperature decarbonized flue gas (90℃) can be directly discharged through the two-way valve V-1, and the low-temperature synthesis gas (90℃) can be introduced into the condenser E-4 for separation and purification and enter the synthesis gas storage tank S-1 for subsequent high-value-added chemical conversion and utilization. The water generated by the condenser E-4 passes through the two-way valve V-10 and is introduced into the electrolytic cell M-3 through the circulating pump P-2 for electrolytic recycling.

[0067] The redundant valley electricity or green electricity of the power plant is used to electrolyze water, and the hydrogen obtained at the cathode is used as the captured CO 2 In-situ hydrogenation is used to prepare raw materials for chemical products; at the same time, the oxygen produced by the anode can replace the air in the original combined cycle power generation system, provide an oxygen-rich environment for the fuel, improve the power generation efficiency of the gas turbine, and enhance the peak load regulation capacity of the power plant.

[0068] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0069] The examples of the present invention have been specifically described above. However, the present invention is not limited to the described embodiments. Those skilled in the art can also make various equivalent modifications or substitutions without departing from the spirit of the present invention. These equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A high-temperature carbon capture and in-situ conversion and utilization system for gas-steam combined cycle power generation coupled with electrolytic water, characterized in that, it includes: a combined cycle power generation unit subsystem, a carbon capture and in-situ conversion subsystem, and an electrolytic water subsystem, the carbon capture and in-situ conversion subsystem captures carbon from the high-temperature carbon-containing flue gas discharged from the gas turbine generator set of the combined cycle power generation unit subsystem and conducts in-situ conversion to obtain target chemical products. The high-temperature decarbonized flue gas and product gas respectively return to the waste heat boiler to drive the steam turbine generator set to generate electricity; the hydrogen required for the carbon conversion process is provided by the electrolytic water system; the electric energy of the electrolytic water subsystem is provided by the valley electricity or green electricity of the power plant, and the oxygen generated by electrolyzing water provides an oxygen-enriched combustion atmosphere for the gas turbine, the combined cycle power generation unit subsystem includes a gas turbine generator set and a steam turbine generator set; the carbon capture and in-situ conversion subsystem is embedded between the gas turbine outlet of the gas turbine generator set and the waste heat boiler inlet of the steam turbine generator set, and includes an intake control unit, an adsorption and conversion reaction tower, a detection and control system, a water vapor separator and a gas transportation unit, the electrolytic water subsystem includes a water electrolysis cell, and an oxygen storage tank and a hydrogen storage tank respectively connected to the anode and cathode of the electrolysis cell; the oxygen storage tank is connected to a compressor through a valve, and the hydrogen storage tank is connected to the adsorption and conversion reaction tower through a valve, the intake control unit includes an intake program control device for high-temperature carbon-containing flue gas, hydrogen, and nitrogen; at least two adsorption and conversion reaction towers are arranged in parallel, including a reactor and an internal heat exchange unit, and an adsorption / catalytic bifunctional material is arranged in the reactor.

2. The high-temperature carbon capture and in-situ conversion and utilization system for gas-steam combined cycle power generation coupled with electrolytic water according to claim 1, characterized in that, the gas turbine generator set includes a compressor, a combustion chamber, a gas turbine, a gas turbine generator, and a heat exchanger; the steam turbine generator set includes a waste heat boiler, a steam turbine, a steam turbine generator, a condenser, a gas transportation unit, and a circulation pump, wherein, in the gas turbine generator set, the compressor, the combustion chamber, and the gas turbine are sequentially connected to form a Brayton cycle unit to drive the gas turbine generator to generate electricity; the waste heat boiler, the steam turbine, the condenser, and the circulation pump are sequentially connected in a cycle to form a Rankine cycle unit to drive the steam turbine generator to generate electricity.

3. The high-temperature carbon capture and in-situ conversion and utilization system for gas-steam combined cycle power generation coupled with electrolytic water according to claim 1, characterized in that: wherein, the reactor is a fixed bed, a fluidized bed or a moving bed.

4. A method for high-temperature carbon capture and in-situ conversion and utilization using the system according to any one of claims 1 to 3, characterized in that, it includes the following steps: (1) In the carbon capture and in-situ conversion subsystem, the high-temperature carbon-containing flue gas generated by the gas turbine of the combined cycle power generation unit subsystem, carbon dioxide is adsorbed by the adsorption / catalytic bifunctional material and is in-situ catalytically hydrogenated to target chemical products with the participation of hydrogen generated by the electrolytic water subsystem; (2) The high-temperature decarbonized flue gas and high-temperature product gas generated in step (1) are heat exchanged in the waste heat boiler to drive the steam turbine generator to generate electricity; the low-temperature decarbonized flue gas after the heat exchange is directly discharged, and the low-temperature target chemical product is stored as a raw material for chemical production or as a fuel for gas-fired power generation, and the condensed water provides a water source for the water electrolysis subsystem; (3) The combined cycle power generation unit subsystem provides electrical energy to the water electrolysis subsystem, and the oxygen generated by electrolysis provides an oxygen-rich environment for fuel combustion in the combustion chamber of the combined cycle power generation unit subsystem.

5. The method according to claim 4, characterized in that: in, Step (1) specifically includes the following steps: According to the reaction temperature required for the carbon capture and in-situ conversion process, the high-temperature carbon-containing flue gas enters the adsorption and conversion reaction tower after heat exchange and cooling or directly. The carbon dioxide in the flue gas is adsorbed and captured by the adsorption / catalysis bifunctional material, and the reaction temperature is controlled during the capture process. After the current reaction tower is saturated with adsorption, it is switched to other parallel reaction towers to continue carbon capture. At the same time, after purging the current reaction tower with nitrogen, preheated hydrogen is introduced to reduce the adsorbed CO 2 for in-situ catalytic conversion to obtain the target chemical product. Other parallel reaction towers are also successively subjected to adsorption, purging, and in-situ hydrogenation conversion; Step (2) comprises the following steps: The high-temperature decarbonized flue gas and high-temperature product gas generated in the adsorption and conversion reaction tower are respectively introduced into the waste heat boiler for heat exchange to transfer heat to water vapor, driving the steam turbine generator set to generate electricity; the low-temperature decarbonized flue gas is directly discharged, and the low-temperature product gas enters the storage tank after being dehydrated by the water-gas separator. Among them, the fuel product gas that can be used as gas-fired power generation is introduced into the combustion chamber for combustion and utilization, forming an artificial carbon cycle, and other products are used for high value-added chemical industry; the water generated by the water-gas separator is introduced into the electrolytic cell through a circulating pump for electrolysis; Step (3) comprises the following steps: The redundant valley electricity or green electricity after peak shaving of the combined cycle power generation subsystem is input into the electrolytic cell for water electrolysis, and the generated oxygen and hydrogen are transported to the oxygen storage tank and the hydrogen storage tank respectively through pipelines; the oxygen in the oxygen storage tank is mixed with the air, compressed by the compressor, and then passed into the combustion chamber of the gas turbine generator set together with the fuel for oxygen-enriched combustion, thereby driving the gas turbine generator to generate electricity.

6. The method according to claim 5, characterized in that: in, In step (1), in the adsorption / catalysis dual-functional material, the adsorption active component is an alkali metal oxide or an alkaline earth metal oxide, and the catalytic active component is a bimetallic catalyst, including a nickel bimetallic, an iron bimetallic, a copper bimetallic, a platinum, ruthenium, rhodium or zirconium noble metal catalyst; The way to control the reaction temperature during the capture process is as follows: for exothermic reactions, the heat needs to be removed through the heat exchange unit inside the adsorption and conversion reaction tower; for endothermic reactions, the 900-1100℃ high-temperature flue gas generated by the combustion heater is passed into the jacket of the adsorption and conversion reaction tower to supplement the heat for the carbon conversion reaction; In-situ CO 2 The catalytic conversion is mainly based on the reverse water gas shift reaction, methanation reaction, methanol synthesis by hydrogenation or olefin synthesis by hydrogenation; The target chemical product is methane, synthesis gas, low-carbon alcohol, olefin or light fuel.

7. The method according to claim 5, characterized in that: in, In step (1), when the adsorption active component is calcium oxide, the high-temperature carbon-containing flue gas directly enters the adsorption and conversion reaction tower; when the adsorption active component is magnesium oxide, the high-temperature carbon-containing flue gas enters the adsorption and conversion reaction tower after heat exchange and cooling.

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