A semi-closed combined cycle flue gas recovery system and method

Abstract

This invention relates to the field of power generation technology, specifically to a semi-closed combined cycle flue gas recovery system and method. The system includes a separator assembly, a gas turbine, and a waste heat boiler. The gas turbine is connected to the separator assembly, and the waste heat boiler is connected to the gas turbine, forming a circulation loop between the gas turbine and the waste heat boiler. Argon gas is separated from the air by the separator assembly and stored, then fed into the gas turbine. The flue gas output from the gas turbine undergoes heat exchange in the waste heat boiler before being reintroduced into the gas turbine for circulation. Argon is used as the circulating working fluid in the gas turbine for a Brayton cycle, increasing the heat capacity of the working fluid and thus improving its thermodynamic properties, thereby increasing the cycle efficiency. Furthermore, by deeply integrating air separation, ammonia synthesis, and supersaturated steam processes from the waste heat boiler, the energy utilization rate of the unit's flue gas recovery is improved, thereby increasing power generation efficiency.

Description

Technical Field

[0001] This invention relates to the field of power generation technology, and specifically to a semi-closed combined cycle flue gas recovery system and method. Background Technology

[0002] The increase in carbon dioxide levels in the Earth's atmosphere is a major cause of the greenhouse effect and drastic climate change. Improving power generation efficiency and reducing emissions of carbon dioxide and nitrogen oxides in exhaust gases are significant technological challenges facing the fossil fuel power generation industry. Combined cycle gas turbines are thermal systems that generate electricity by burning natural gas. Current technologies use open-cycle gas turbines to drive generators, and then recover the heat from the flue gas emitted by the gas turbines in a waste heat boiler to produce high-temperature, high-pressure steam.

[0003] In existing technologies, pollutants in flue gas are treated by flue gas purification devices before being released into the atmosphere, such as monoethanolamine (MEA) liquid absorption and selective catalytic reduction (SCR) technology. However, separating or washing carbon dioxide and nitrogen oxides from the flue gas emitted from combined cycle systems consumes a large amount of electrical energy, reduces the operating efficiency of gas turbines, and leads to increased power plant electricity costs. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the flue gas of gas turbines contains a large amount of pollutants such as carbon dioxide and nitrogen oxides.

[0005] To address the above problems, the present invention provides a semi-closed combined cycle flue gas recovery system, comprising:

[0006] Separator assembly, suitable for separating different components in air;

[0007] A gas turbine is connected to the separator assembly;

[0008] A waste heat boiler is connected to the gas turbine and is adapted to recover heat from the flue gas of the gas turbine, and the flue gas in the gas turbine and the waste heat boiler form a circulation loop.

[0009] Furthermore, in this semi-closed combined cycle flue gas recovery system, the gas turbine includes:

[0010] A compressor is connected to the separator assembly and the waste heat boiler;

[0011] The combustion chamber is connected to the compressor and the waste heat boiler;

[0012] A turbine, connected to the combustion chamber and the waste heat boiler, is adapted to drive a generator to generate electricity.

[0013] Furthermore, this semi-closed combined cycle flue gas recovery system also includes:

[0014] A natural gas source is connected to the combustion chamber and is adapted to provide fuel to the combustion chamber;

[0015] A catalytic reformer, connected to the natural gas source and the waste heat boiler, is adapted to produce hydrogen.

[0016] A catalytic reactor, located inside a waste heat boiler, is connected to the separator assembly and the catalytic reformer, and is suitable for ammonia synthesis.

[0017] A first carbon trap, connected to the catalytic reactor, the waste heat boiler, and the compressor, is adapted to absorb carbon dioxide from the flue gas.

[0018] Furthermore, this semi-closed combined cycle flue gas recovery system also includes:

[0019] A catalytic converter is connected to the waste heat boiler, the catalytic reformer, and the catalytic reactor.

[0020] Furthermore, this semi-closed combined cycle flue gas recovery system also includes:

[0021] A second carbon trap, connected to the catalytic converter and the catalytic reactor, is adapted to absorb carbon dioxide from the catalytic converter.

[0022] Furthermore, this semi-closed combined cycle flue gas recovery system also includes:

[0023] A mixing pressurizer is connected to the second carbon trap, the separator assembly, and the catalytic reactor.

[0024] Furthermore, this semi-closed combined cycle flue gas recovery system also includes:

[0025] A water pump, connected to the waste heat boiler, is adapted to supply water to the waste heat boiler;

[0026] An evaporator, installed inside the waste heat boiler and connected to the water pump, is adapted to generate steam.

[0027] A superheater is installed inside the waste heat boiler and connected to the evaporator, the catalytic converter, and the catalytic reformer.

[0028] Furthermore, in this semi-closed combined cycle flue gas recovery system, the separator assembly includes:

[0029] Air pump;

[0030] A separator, connected to the air pump, the compressor and the mixing pressurizer, is suitable for separating different components in the air.

[0031] Furthermore, this semi-closed combined cycle flue gas recovery system also includes:

[0032] A first heat exchanger is connected to the superheater, the catalytic reformer and the catalytic converter, and a circulation loop is formed between the first heat exchanger and the catalytic reformer;

[0033] The second heat exchanger is connected to the water pump, the evaporator, the first carbon trap and the second carbon trap;

[0034] A reheater is connected to the compressor and the combustion chamber;

[0035] A flue gas purifier is connected to the first carbon trap and the compressor.

[0036] The present invention also provides a semi-closed combined cycle flue gas recovery method, employing the above-mentioned semi-closed combined cycle flue gas recovery system, comprising:

[0037] Step S1: The separator separates argon, oxygen, and nitrogen from the air;

[0038] Step S2: Introduce the argon and oxygen into the gas turbine for combustion;

[0039] Step S3: Input the flue gas after combustion in the gas turbine into the waste heat boiler for heat exchange;

[0040] Step S4: The heat-exchanged flue gas is reintroduced into the gas turbine;

[0041] Step S5: The supersaturated steam after heat exchange in the waste heat boiler is transported to the catalytic reformer to produce hydrogen;

[0042] Step S6: The hydrogen gas obtained in step 5 and the nitrogen gas separated in step 1 are transported to the catalytic reactor to synthesize ammonia;

[0043] Step S7: The synthesized ammonia is transported to the first carbon trap and the second carbon trap to absorb carbon dioxide from the flue gas emitted by the waste heat boiler and the catalytic converter;

[0044] In step S8, argon gas is continuously separated from step 1, stored, and added to the flue gas of the combined cycle unit as supplementary argon gas.

[0045] The present invention has the following advantages:

[0046] 1. The semi-closed combined cycle flue gas recovery system provided by the present invention includes a separator assembly, a gas turbine, and a waste heat boiler. The separator assembly is adapted to separate different components in the air. The gas turbine is connected to the separator assembly, and the waste heat boiler is connected to the gas turbine. It is adapted to recover heat from the flue gas of the gas turbine, and the flue gas in the gas turbine and the waste heat boiler form a circulation loop.

[0047] Argon gas is continuously separated from the air by a separator assembly and stored in a certain amount (approximately 1%). This argon gas is then fed into a gas turbine. The flue gas output from the gas turbine undergoes heat exchange in a waste heat boiler before being reintroduced into the gas turbine for recirculation. Argon has a high specific heat ratio and high thermal conductivity; its density is 1.5 times that of nitrogen, and its specific heat capacity ratio is 1.67, greater than air's 1.4. Furthermore, argon's excellent thermal conductivity makes it ideal for use as a working fluid in the gas turbine during the Brayton cycle. This increases the working fluid's heat capacity, thereby improving its thermodynamic properties and increasing cycle efficiency. Recirculating the argon gas from the flue gas back into the gas turbine allows for the reuse of its energy, reducing carbon oxide and nitrogen oxide emissions and increasing the utilization rate of energy in the flue gas, ultimately increasing power generation efficiency.

[0048] 2. The semi-closed combined cycle flue gas recovery system provided by the present invention includes a gas turbine comprising a compressor, a combustion chamber and a turbine. The compressor is connected to a separator assembly and a waste heat boiler. The combustion chamber is connected to the compressor and the waste heat boiler. The turbine is connected to the combustion chamber and the waste heat boiler. The turbine is adapted to drive a generator to generate electricity.

[0049] The compressor pressurizes the argon and oxygen separated from the separation component and inputs them into the combustion chamber. The oxygen and fuel participate in combustion, converting chemical energy into mechanical energy to drive the turbine to do work, which in turn drives the generator to generate electricity. The flue gas discharged from the turbine is then reheated in the waste heat boiler and input back into the compressor. Since argon is an inert gas, it does not burn with oxygen in the combustion chamber. Therefore, the argon in the gas turbine is not consumed and can be recovered and reused after the unit is shut down. Reusing the flue gas containing argon not only saves energy but also improves the energy utilization rate of the flue gas, thereby increasing the efficiency of power generation.

[0050] 3. The semi-closed combined cycle flue gas recovery system provided by the present invention further includes a natural gas source, a catalytic reformer, a catalytic reactor, and a first carbon trap. The natural gas source is connected to the combustion chamber and is suitable for providing fuel to the combustion chamber. The catalytic reformer is connected to the natural gas source and the waste heat boiler and is suitable for generating hydrogen. The catalytic reactor is located inside the waste heat boiler and is connected to the separator assembly and the catalytic reformer, and is suitable for synthesizing ammonia. The first carbon trap is connected to the catalytic reactor, the waste heat boiler, and the compressor and is suitable for absorbing carbon dioxide in the flue gas.

[0051] Natural gas can provide fuel for gas turbines, converting chemical energy into mechanical energy in the combustion chamber to drive generators. It can also be used as a raw material in catalytic reformers, where waste heat boilers recover heat from flue gas to reform methane and water vapor in the natural gas into hydrogen and carbon oxides. The reformed hydrogen, along with nitrogen separated from the separator components, is then fed into a catalytic reactor. Using heat from the waste heat boiler, the reactor catalytically heats the mixture to produce ammonia. The synthesized ammonia is fed into a first carbon trap, where it absorbs carbon dioxide produced in the waste heat boiler and catalytic reformer, synthesizing ammonium bicarbonate. This reduces emissions of carbon oxides and nitrogen oxides, improving the environmental impact of power generation. The heat required for the catalytic reformer and catalytic reactor can be recovered and reused from the gas turbine's flue gas using the waste heat boiler, saving energy and improving energy utilization efficiency, thus increasing power generation efficiency. Furthermore, the ammonium bicarbonate synthesized in the first carbon trap can be used as fertilizer.

[0052] 4. The semi-closed combined cycle flue gas recovery system provided by the present invention further includes a catalytic converter connected to a waste heat boiler, a catalytic reformer, and a catalytic reactor. The catalytic converter can catalytically synthesize carbon monoxide produced in the catalytic reformer with water into carbon dioxide and hydrogen. The hydrogen is then synthesized into ammonia with nitrogen in the catalytic reactor. The carbon dioxide is absorbed by the flue gas from the waste heat boiler in the first carbon trap to synthesize ammonium bicarbonate. By setting up the catalytic converter, toxic carbon monoxide can be converted into carbon dioxide, reducing toxic gases and improving the safety of the power generation process. At the same time, the heat required by the catalytic converter can be recovered and reused by the waste heat boiler from the heat emitted by the gas turbine, saving energy and improving energy utilization efficiency, thereby improving the efficiency of power generation. Furthermore, the carbon dioxide can also be synthesized into ammonium bicarbonate for use as fertilizer, further reducing carbon emissions.

[0053] 5. The semi-closed combined cycle flue gas recovery system provided by the present invention further includes a second carbon trap connected to the catalytic converter and the catalytic reactor, which is suitable for absorbing carbon dioxide in the catalytic converter, thereby increasing the purity of hydrogen gas input to the catalytic reactor, improving the ammonia synthesis rate in the catalytic reactor, and further reducing carbon emissions.

[0054] 6. The semi-closed combined cycle flue gas recovery system provided by the present invention further includes a water pump, an evaporator, and a superheater. The water pump is connected to the waste heat boiler and is suitable for supplying water to the waste heat boiler. The evaporator is installed inside the waste heat boiler and connected to the water pump, and is suitable for generating steam. The superheater is installed inside the waste heat boiler and is connected to the evaporator, the catalytic converter, and the catalytic reformer.

[0055] A water pump feeds water into the evaporator, where it exchanges heat with the flue gas from the waste heat boiler to heat the water into steam. The steam is then heated into superheated saturated steam by a superheater. The superheated saturated steam output from the superheater can be used for industrial heating, and can also be fed into the catalytic converter and catalytic reformer to provide heat. This fully utilizes the heat from the gas turbine flue gas in the waste heat boiler, saving energy.

[0056] 7. The semi-closed combined cycle flue gas recovery system provided by the present invention includes an air pump and a separator assembly. The separator is connected to the air pump, the compressor and the mixing pressurizer. The separator is suitable for separating different components in the air.

[0057] An air pump draws air into a separator, where oxygen, nitrogen, argon, and carbon dioxide are separated using renewable or surplus electricity. The separated oxygen and argon are fed into a gas turbine to generate electricity, while the separated nitrogen is fed into a mixing and pressurizing unit to mix with hydrogen for ammonia synthesis. The separated carbon dioxide can be sold or stored as dry ice. This system fully utilizes electricity generated from renewable sources or surplus electricity and can convert some of the electrical energy into chemical energy for storage, saving energy and improving the efficiency of electricity utilization.

[0058] 8. The semi-closed combined cycle flue gas recovery system provided by the present invention further includes a first heat exchanger, a second heat exchanger, a reheater, and a flue gas purifier. The first heat exchanger is connected to a superheater, a catalytic reformer, and a catalytic converter, and a circulation loop is formed between the first heat exchanger and the catalytic reformer. The second heat exchanger is connected to a water pump, an evaporator, a first carbon trap, and a second carbon trap. The reheater is connected to a compressor and a combustion chamber. The flue gas purifier is connected to the first carbon trap and the compressor.

[0059] The first heat exchanger heats the saturated steam output from the superheater with the intermediate products from the catalytic reformer, then feeds it back into the catalytic reformer to provide heat for the chemical reaction. The second heat exchanger heats the water generated during ammonia synthesis in the catalytic reactor with water from the pump, heating the water before it is fed into the evaporator. By using the first and second heat exchangers, the heat generated during ammonia and hydrogen production can be fully utilized, saving energy and improving energy efficiency. The flue gas purifier removes impurities from the flue gas, such as oil, dust, and mist, resulting in higher purity argon gas circulating into the gas turbine and reducing the damage and impact of impurities on the equipment.

[0060] 9. The semi-closed combined cycle flue gas recovery method provided by this invention separates argon gas, which has a high specific heat ratio and high thermal conductivity, from the air and inputs it into a gas turbine to participate in power generation. Since the specific heat ratio of argon gas is greater than that of air and its density is 1.5 times that of nitrogen gas, argon gas is used as a working fluid to input into the gas turbine for Brayton cycle, which increases the heat capacity of the working fluid and thus improves the thermodynamic performance of the circulating working fluid, thereby improving the cycle efficiency. Furthermore, recirculating the argon gas in the flue gas into the gas turbine allows for the reuse of the energy in the argon gas, improving the energy utilization rate in the flue gas and thus increasing the power generation efficiency. Attached Figure Description

[0061] 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.

[0062] Figure 1 A schematic diagram of a semi-closed combined cycle flue gas recovery system provided in this embodiment of the invention.

[0063] Explanation of reference numerals in the attached figures:

[0064] 100. Separator assembly; 101. Air pump; 102. Separator; 103. Nitrogen storage tank; 104. Carbon dioxide storage tank; 200. Gas turbine; 201. Compressor; 202. Combustion chamber; 203. Turbine; 300. Waste heat boiler; 301. Catalytic reactor; 302. Evaporator; 303. Superheater; 304. Reheater; 400. Generator; 500. Natural gas source; 600. Catalytic reformer; 700. First carbon trap; 800. Catalytic converter; 900. Second carbon trap; 110. Mixing pressurizer; 120. Water pump; 130. First heat exchanger; 140. Second heat exchanger; 150. Flue gas purifier; 160. Argon storage tank; 170. Hydrogen storage tank; 180. Make-up water device; 190. Ammonium bicarbonate storage tank. Detailed Implementation

[0065] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0066] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," 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 the invention and for 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 limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0067] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can 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 according to the specific circumstances.

[0068] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0069] Example 1

[0070] like Figure 1 As shown, the semi-closed combined cycle flue gas recovery system provided in this embodiment includes a separator assembly 100, a gas turbine 200, and a waste heat boiler 300. The separator assembly 100 is suitable for separating different components in the air. The gas turbine 200 is connected to the separator assembly 100, and the waste heat boiler 300 is connected to the gas turbine 200 and is suitable for recovering heat from the flue gas in the gas turbine 200. The flue gas in the gas turbine 200 and the waste heat boiler 300 form a circulation loop.

[0071] Argon gas is separated from the air by the separator assembly 100 and stored in a certain amount. The argon gas is then fed into the gas turbine 200. After heat exchange in the waste heat boiler 300, the flue gas containing argon gas is fed back into the gas turbine 200 for circulation. Argon gas has a high specific heat ratio and high thermal conductivity. Its density is 1.5 times that of nitrogen gas, and its specific heat capacity ratio is 1.67, which is greater than the specific heat capacity ratio of air (1.4). Argon gas also has good thermal conductivity. Using argon gas as a working fluid in the gas turbine 200 for the Brayton cycle increases the heat capacity of the working fluid, thereby improving the thermodynamic performance of the circulating working fluid and increasing the circulation efficiency. Furthermore, the recirculation of argon gas from the flue gas into the gas turbine 200 allows for the reuse of the energy in the argon gas, reducing the emission of carbon oxides and nitrogen oxides and improving the energy utilization rate in the flue gas, thus increasing the efficiency of power generation.

[0072] In this embodiment, the separator assembly 100 can use electricity generated by renewable energy sources (such as solar energy, wind energy, etc.) or surplus electricity from the power grid to remove carbon dioxide from the air by deep cooling the air to the boiling point of carbon dioxide (-78°C), and then continue to deep cool the air to the boiling point of nitrogen (-185°C) to remove nitrogen from the air, thereby obtaining liquid argon and oxygen, which are then transported to the gas turbine 200 at a temperature of -180°C as working fluid. Argon is added to the working fluid according to the requirements of the gas turbine 200 intake composition to form gas turbine 200 circulating flue gas with argon as the main component.

[0073] In this embodiment, the gas turbine 200 includes a compressor 201, a combustion chamber 202, and a turbine 203. The compressor 201 is connected to the separator assembly 100 and the waste heat boiler 300. The combustion chamber 202 is connected to the compressor 201 and the waste heat boiler 300. The turbine 203 is connected to the combustion chamber 202 and the waste heat boiler 300. The turbine 203 is adapted to drive the generator 400 to generate electricity.

[0074] Compressor 201 pressurizes argon and oxygen separated from the cryogenic air in the separation assembly to a high-pressure working fluid of 2MPa and 200℃. This fluid is then reheated to 400℃ in the waste heat boiler 300 before being fed into the combustion chamber 202. Oxygen and fuel participate in combustion, converting chemical energy into mechanical energy to drive the turbine 203, which in turn drives the generator 400 to generate electricity. The flue gas discharged from the turbine 203 at 600℃ is then reheated in the waste heat boiler 300 before being reintroduced into compressor 201. Since argon is an inert gas, it does not burn with oxygen in the combustion chamber 202. Therefore, the argon in the gas turbine 200 is not consumed and can be reused. Reusing the argon-containing flue gas saves energy and improves the energy utilization rate of the flue gas, thereby increasing the efficiency of power generation. The heat in the high-temperature flue gas can be used to reheat the argon and generate water vapor, allowing for the full recovery and reuse of energy from the flue gas.

[0075] In this embodiment, the semi-closed combined cycle flue gas recovery system further includes a natural gas source 500, a catalytic reformer 600, a catalytic reactor 301, and a first carbon trap 700. The natural gas source 500 is connected to the combustion chamber 202 and is suitable for providing fuel to the combustion chamber 202. The catalytic reformer 600 is connected to the natural gas source 500 and the waste heat boiler 300 and is suitable for generating hydrogen. The catalytic reactor 301 is disposed inside the waste heat boiler 300 and is connected to the separator assembly 100 and the catalytic reformer 600 and is suitable for synthesizing ammonia. The first carbon trap 700 is connected to the catalytic reactor 301, the waste heat boiler 300, and the compressor 201 and is suitable for absorbing carbon dioxide in the flue gas.

[0076] Natural gas source 500 can provide fuel for gas turbine 200, converting chemical energy into mechanical energy in combustion chamber 202 to drive generator 400 to generate electricity. Simultaneously, it can also be used as raw material in catalytic reformer 600, where waste heat boiler 300 recovers heat from flue gas to reform methane and water vapor in natural gas into hydrogen and carbon oxides at high temperature. The reformed hydrogen and nitrogen separated from separator assembly 100 are then fed into catalytic reactor 301, where heat from waste heat boiler 300 is used for catalytic heating and a reaction to produce ammonia. The synthesized ammonia is then fed into the... The carbon capture device 700 can absorb the carbon dioxide produced in the waste heat boiler 300 and the catalytic reformer 600 and synthesize ammonium bicarbonate, reducing the emissions of carbon oxides and nitrogen oxides and improving the environmental protection effect in power generation. The heat required by the catalytic reformer 600 and the catalytic reactor 301 can be recovered and reused by the waste heat boiler 300 from the heat emitted by the gas turbine 200, saving energy and improving the energy utilization rate, thereby improving the efficiency of power generation. In addition, the ammonium bicarbonate synthesized in the first carbon capture device 700 can also be used as fertilizer.

[0077] After the first carbon trap 700 removes carbon dioxide from the flue gas, the remaining components are argon and oxygen. These are then mixed with the argon and oxygen separated in the separator assembly 100. By supplementing with additional argon, a working fluid with a volume fraction of 75% argon and 25% oxygen is formed and returned to the gas turbine 200 inlet. In this embodiment, helium or other inert gases can also be added to the working fluid at the gas turbine inlet to form a mixture of helium + argon with a volume fraction of 25% oxygen.

[0078] In this embodiment, the catalytic reformer 600 is not specifically limited. To reflect real-world conditions, an electrically heated catalytic reformer 600 is used. This reformer can utilize electricity generated from renewable energy sources or surplus electricity from the power grid to power the reformer 600. Methane from natural gas is heated at high temperatures with steam generated in the waste heat boiler 300 and reformed into hydrogen and carbon monoxide. The ratio of these components can be adjusted by selecting the feed rate of the reactants (the ratio of natural gas to steam ranges from 1.1 to 3.4). Methane and steam are reformed into hydrogen, carbon monoxide, and a small amount of carbon dioxide using a nickel-based catalyst under electrically heated conditions of 800℃-1000℃ and 14bar-20bar. The methane conversion rate is as high as 99.5%, and the purity of the produced hydrogen is as high as 99.9%.

[0079] In this embodiment, the intermediate product hydrogen from the catalytic reformer 600 and the nitrogen separated from the deep cryogenic air are mixed and pressurized before entering the catalytic reactor 301 in the waste heat boiler 300 for catalytic heating. Under the conditions of 400℃-450℃ and 20MPa, they undergo a chemical reaction to produce ammonia. The ammonia synthesized in the catalytic reactor 301 is then converted into ammonia water through the water replenishment device 180.

[0080] In this embodiment, using ammonia as a solvent for chemical absorption of CO2 can achieve a removal efficiency of 95%-99%.

[0081] In this embodiment, the semi-closed combined cycle flue gas recovery system also includes a catalytic converter 800 connected to the waste heat boiler 300, the catalytic reformer 600, and the catalytic reactor 301. The catalytic converter 800 can catalytically synthesize carbon monoxide and water generated in the catalytic reformer 600 into carbon dioxide and hydrogen. The hydrogen is then synthesized into ammonia with nitrogen in the catalytic reactor 301. The carbon dioxide is absorbed by the flue gas from the waste heat boiler 300 in the first carbon trap 700 to synthesize ammonium bicarbonate. By setting up the catalytic converter 800, toxic carbon monoxide can be converted into carbon dioxide, reducing toxic gases in power generation and improving safety during the power generation process. At the same time, the heat required by the catalytic converter 800 can be recovered and reused by the waste heat boiler 300 from the heat emitted by the gas turbine 200, saving energy and improving energy utilization efficiency, thereby improving power generation efficiency. Furthermore, the carbon dioxide converted from carbon monoxide can also be used to synthesize ammonium bicarbonate for fertilizer, further reducing carbon emissions.

[0082] This embodiment does not specifically limit the catalytic converter 800. To conform to reality, the catalytic converter 800 in this embodiment adopts a gas-water catalytic converter, which is divided into two reaction stages: the first stage is filled with chromium to promote the operation of the iron oxide catalyst at 350℃-400℃; the second stage is filled with copper to promote the operation of zinc oxide at around 200℃.

[0083] In this embodiment, the semi-closed combined cycle flue gas recovery system also includes a second carbon trap 900 connected to the catalytic converter 800 and the catalytic reactor 301. It is suitable for absorbing carbon dioxide in the catalytic converter 800, so that the hydrogen input into the catalytic reactor 301 has higher purity, which improves the ammonia synthesis rate in the catalytic reactor 301 and can further reduce carbon emissions.

[0084] In this embodiment, the water replenishment device 180 adds water to produce ammonia water from ammonia gas, which is then input into the first carbon trap 700 and the second carbon trap 900 to absorb carbon dioxide.

[0085] In this embodiment, the semi-closed combined cycle flue gas recovery system also includes a mixing and pressurizing unit 110 connected to the second carbon trap 900, the separator assembly 100 and the catalytic reactor 301, for mixing and pressurizing hydrogen and nitrogen to 20 MPa.

[0086] In this embodiment, the semi-closed combined cycle flue gas recovery system further includes a water pump 120, an evaporator 302, and a superheater 303. The water pump 120 is connected to the waste heat boiler 300 and is suitable for supplying water to the waste heat boiler 300. The evaporator 302 is located inside the waste heat boiler 300 and is connected to the water pump 120, and is suitable for generating steam. The superheater 303 is located inside the waste heat boiler 300 and is connected to the evaporator 302, the catalytic converter 800, and the catalytic reformer 600.

[0087] Pump 120 pressurizes water to 2.5MPa and inputs it into evaporator 302. It uses the heat from the flue gas in waste heat boiler 300 to heat the water into steam. Then, the steam is heated into superheated saturated steam at 400℃-450℃ by superheater 303. The superheated saturated steam output from superheater 303 can be used for industrial heating. It can also be input into catalytic converter 800 and catalytic reformer 600 to provide heat. The heat from the flue gas in gas turbine 200 is fully exchanged and reused in waste heat boiler 300, saving energy.

[0088] In this embodiment, the separator assembly 100 includes an air pump 101 and a separator 102. The separator 102 is connected to the air pump 101, the compressor 201 and the mixing pressurizer 110. The separator 102 is adapted to separate different components in the air.

[0089] Air pump 101 draws air into separator 102, which uses renewable energy or surplus electricity to separate oxygen, nitrogen, argon, and carbon dioxide from the air. The separated oxygen and argon are fed into gas turbine 200 to generate electricity, while the separated nitrogen is fed into mixing and pressurizing mixer 110 to mix with hydrogen for ammonia synthesis. The separated carbon dioxide can be sold or stored as dry ice. This fully utilizes the electricity generated from renewable energy or surplus electricity, and can convert some of the electrical energy into chemical energy for storage, saving energy and improving the utilization rate of electricity.

[0090] In this embodiment, the carbon dioxide separated from the air by cryogenic separation can be sold as dry ice or stored underground or in the deep sea. The liquid oxygen, argon, and nitrogen separated from the air by cryogenic separation are all non-toxic, non-flammable, and not easily leaked. Furthermore, argon and nitrogen are inert gases and can be transported from renewable energy power plants to combined cycle power plants using ordinary industrial storage tanks.

[0091] In this embodiment, the semi-closed combined cycle flue gas recovery system further includes a first heat exchanger 130, a second heat exchanger 140, a reheater 304, and a flue gas purifier 150. The first heat exchanger 130 is connected to the superheater 303, the catalytic reformer 600, and the catalytic converter 800. A circulation loop is formed between the first heat exchanger 130 and the catalytic reformer 600. The second heat exchanger 140 is connected to the water pump 120, the evaporator 302, the first carbon trap 700, and the second carbon trap 900. The reheater 304 is connected to the compressor 201 and the combustion chamber 202. The flue gas purifier 150 is connected to the first carbon trap 700 and the compressor 201.

[0092] The first heat exchanger 130 exchanges heat with the saturated superheated steam (400℃-450℃) output from the superheater 303 and the intermediate product (800℃) in the catalytic reformer 600, raising its temperature before re-introducing it into the catalytic reformer 600 to provide heat for the chemical reaction in the catalytic reformer 600. The second heat exchanger 140 exchanges heat with the water pump 120 generated during ammonia synthesis in the catalytic reactor 301, heating the water before it is fed into the evaporator 302. By setting up the first heat exchanger 130 and the second heat exchanger 140, the heat generated during ammonia and hydrogen production can be fully utilized, saving energy and improving energy efficiency. The flue gas purifier 150 can purify impurities in the flue gas, such as oil, dust, and mist, resulting in higher purity argon gas circulating into the gas turbine 200 and reducing the damage and impact of impurities on the equipment.

[0093] In summary, the semi-closed combined cycle power generation system provided by this invention can achieve zero emissions with no pollution. The circulating gas mixture has a composition ratio that mimics air, replacing nitrogen in the air with argon, thus allowing for effective compression without altering the compressor 201. The exhaust gas in this invention is entirely composed of argon, oxygen, carbon dioxide, and a small amount of water, so there are no nitrogen oxides, and no nitrogen oxide removal equipment is needed, simplifying the unit's structure and reducing operating costs. The raw material for the ammonia synthesis process in this invention comes from high-temperature, high-pressure steam produced by the waste heat boiler 300, and this process is deeply thermally coupled with the waste heat boiler 300, rationally utilizing the waste heat boiler 300 to recover heat from the flue gas of the gas turbine 200. This invention also incorporates a first carbon trap 700 and a second carbon trap 900. This invention can effectively absorb carbon dioxide from the flue gas of the waste heat boiler 300 and the byproducts of the ammonia synthesis process. The generated ammonium bicarbonate can also be used as fertilizer, increasing economic benefits. Furthermore, after the unit is shut down, the invention can store argon from the flue gas and continuously extract argon from the air using the separator assembly 100, which serves as the working fluid for the gas turbine 200, improving the power generation efficiency of the combined cycle unit. In this invention, the compressor 201 has a low inlet temperature and high efficiency. Combined with the reheater 304 in the waste heat boiler 300, which has the highest temperature, heating the compressed gas at the compressor 201 outlet, the temperature required for natural gas combustion is maintained, and the waste heat from the gas turbine 200 is effectively recovered. This invention eliminates the need for the steam turbine and condenser in traditional generator sets 400, greatly simplifying power plant equipment.

[0094] Example 2

[0095] The semi-closed combined cycle flue gas recovery method provided in this embodiment adopts the semi-closed combined cycle flue gas recovery system in Embodiment 1, and includes the following steps:

[0096] Step S1: Separator 102 separates argon, oxygen, and nitrogen from the air;

[0097] Step S2: Argon and oxygen are introduced into the gas turbine 200 to participate in combustion;

[0098] Step S3: Input the flue gas after combustion in the gas turbine 200 into the waste heat boiler 300 for heat exchange;

[0099] Step S4: The heat-exchanged flue gas is reintroduced into the gas turbine 200;

[0100] Step S5: The supersaturated steam after heat exchange in the waste heat boiler 300 is sent to the catalytic reformer 600 to produce hydrogen.

[0101] Step S6: The hydrogen obtained in step 5 and the nitrogen separated in step 1 are transported to the catalytic reactor 301 to synthesize ammonia.

[0102] Step S7: The synthesized ammonia is transported to the first carbon trap 700 and the second carbon trap 900 to absorb carbon elements in the flue gas emitted from the waste heat boiler 300 and the catalytic converter 800.

[0103] In step S8, argon gas is continuously separated from step 1, stored, and added to the flue gas of the combined cycle unit as supplementary argon gas.

[0104] This method separates argon gas, which has a high specific heat ratio and high thermal conductivity, from the air and inputs it into the gas turbine 200 to participate in power generation. Since the specific heat ratio of argon gas is greater than that of air and its density is 1.5 times that of nitrogen gas, using argon gas as a working fluid in the gas turbine 200 for Brayton cycle increases the heat capacity of the working fluid, thus improving the thermodynamic performance of the circulating working fluid and increasing the cycle efficiency. Recirculating the argon gas from the flue gas back into the gas turbine 200 allows for the reuse of the energy in the argon gas, reducing the emission of carbon oxides and nitrogen oxides and improving the utilization rate of energy in the flue gas, thereby increasing the power generation efficiency. At the same time, the separation of argon, nitrogen, oxygen, and carbon dioxide from the air using renewable energy or surplus electricity provides high-efficiency electricity, and some of the electrical energy can be converted into chemical energy for storage. The waste heat boiler 300 can also recover and reuse the energy in the flue gas of the gas turbine 200.

[0105] The semi-closed combined cycle flue gas recovery method provided by this invention, when performing the ammonia synthesis process, the catalytic reforming process is an endothermic reaction, and electric heating requires the consumption of electrical energy. Excess electricity can be drawn from the power grid at night, and the produced ammonia is stored in a sealed tank in the form of ammonia water. This energy storage method is safe and reliable. After the combined cycle unit starts working during the day, the ammonia water is used to capture carbon dioxide to produce fertilizer.

[0106] When the combined cycle unit is working, argon is continuously fed into the gas turbine 200 from the argon storage tank 160. When the unit is shut down, the flue gas from the waste heat boiler 300 enters the combustion chamber 202 through the recirculation pipeline to remove oxygen, and the remaining argon is returned to the argon storage tank 160.

[0107] When renewable energy sources such as solar and wind power can stably supply electricity, the air cryogenic separator 102 is activated to cryogenically separate liquid oxygen, argon and nitrogen from the air. The oxygen and argon are transported from the renewable energy power plant to the combined cycle power plant, where they are depressurized, expanded and gasified to serve as the working fluid of the gas turbine 200.

[0108] When argon participates in the cycle, it is used as the working fluid with a volume fraction of 80% argon and 20% oxygen. After combustion and oxygen consumption, the flue gas is captured by carbon and has a volume fraction of more than 80% argon and less than 20% oxygen. Therefore, the oxygen-rich mixed gas separated from the separator assembly 100 needs to be added to the gas turbine 200 to maintain the combustion of natural gas in the gas turbine 200.

[0109] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A semi-closed combined cycle flue gas recovery system, characterized by, include: The separator assembly (100) uses electricity generated from renewable energy sources or surplus electricity from the power grid to cryogenically cool air to the boiling point of carbon dioxide to remove carbon dioxide from the air, and then continues to cryogenically cool the air to the boiling point of nitrogen to remove nitrogen from the air, thereby obtaining liquid argon and oxygen. A gas turbine (200) is connected to the separator assembly (100) and feeds argon and oxygen into the gas turbine (200) as working fluids with a volume fraction of 75% argon and 25% oxygen. A waste heat boiler (300) is connected to the gas turbine (200) and is adapted to recover heat from the flue gas of the gas turbine (200), and the flue gas in the gas turbine (200) and the waste heat boiler (300) form a circulation loop; A natural gas source (500) is connected to a combustion chamber (202) and is adapted to provide fuel to the combustion chamber (202); A catalytic reformer (600), connected to the natural gas source (500) and the waste heat boiler (300), is adapted to produce hydrogen; A catalytic reactor (301) is installed inside a waste heat boiler (300), the catalytic reactor (301) is connected to the separator assembly (100) and the catalytic reformer (600), and is suitable for synthesizing ammonia; A first carbon trap (700) is connected to the catalytic reactor (301), the waste heat boiler (300), and the compressor (201), and is adapted to absorb carbon dioxide in the flue gas; The gas turbine (200) includes: A compressor (201) is connected to the separator assembly (100) and the waste heat boiler (300); Combustion chamber (202) is connected to the compressor (201) and the waste heat boiler (300); A turbine (203) is connected to the combustion chamber (202) and the waste heat boiler (300), and the turbine (203) is adapted to drive a generator (400) to generate electricity.

2. The semi-closed combined cycle smoke recovery system of claim 1, wherein, Also includes: A catalytic converter (800) is connected to the waste heat boiler (300), the catalytic reformer (600), and the catalytic reactor (301).

3. The semi-closed combined cycle smoke recovery system of claim 2, wherein, Also includes: A second carbon trap (900), connected to the catalytic converter (800) and the catalytic reactor (301), is adapted to absorb carbon dioxide from the catalytic converter (800).

4. The semi-closed combined cycle smoke recovery system of claim 3, wherein, Also includes: A mixing pressurizer (110) is connected to the second carbon trap (900), the separator assembly (100), and the catalytic reactor (301).

5. The semi-closed combined cycle smoke recovery system of claim 4, wherein, Also includes: A water pump (120) is connected to the waste heat boiler (300) and is adapted to supply water to the waste heat boiler (300); An evaporator (302) is installed inside the waste heat boiler (300) and connected to the water pump (120), and is adapted to generate steam; A superheater (303) is installed inside the waste heat boiler (300) and connected to the evaporator (302), the catalytic converter (800) and the catalytic reformer (600).

6. The semi-closed combined cycle smoke recovery system of claim 5, wherein, The separator assembly (100) includes: Air pump (101); The separator (102), connected to the air pump (101), the compressor (201) and the mixing pressurizer (110), is adapted to separate different components in the air.

7. The semi-closed combined cycle flue gas recovery system according to claim 6, characterized in that, Also includes: The first heat exchanger (130) is connected to the superheater (303), the catalytic reformer (600) and the catalytic converter (800), and a circulation loop is formed between the first heat exchanger (130) and the catalytic reformer (600); The second heat exchanger (140) is connected to the water pump (120), the evaporator (302), the first carbon trap (700) and the second carbon trap (900); A reheater (304) is connected to the compressor (201) and the combustion chamber (202); The flue gas purifier (150) is connected to the first carbon trap (700) and the compressor (201).

8. A semi-closed combined cycle flue gas recovery method, characterized by, The semi-closed combined cycle flue gas recovery system according to claim 7 includes: Step S1: The separator (102) separates argon, oxygen and nitrogen from the air; Step S2: The argon and oxygen are fed into the gas turbine (200) to participate in combustion; Step S3: Input the flue gas after combustion in the gas turbine (200) into the waste heat boiler (300) for heat exchange; Step S4: The heat-exchanged flue gas is reintroduced into the gas turbine (200); Step S5: The supersaturated steam after heat exchange in the waste heat boiler (300) is sent to the catalytic reformer (600) to produce hydrogen; Step S6: The hydrogen obtained in step 5 and the nitrogen separated in step 1 are transported to the catalytic reactor (301) to synthesize ammonia; Step S7: The synthesized ammonia is transported to the first carbon trap (700) and the second carbon trap (900) to absorb carbon elements in the flue gas emitted from the waste heat boiler (300) and the catalytic converter (800); In step S8, argon gas is continuously separated from step 1, stored, and added to the flue gas of the combined cycle unit as supplementary argon gas.

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