A power generation system coupling a combined cycle unit with a molten carbonate electrolyzer

Abstract

Embodiments of the present disclosure provide a power generation system coupled with a molten carbonate electrolyzer, comprising a generator, one side of which is connected with a gas turbine to drive power generation, and the other side is sequentially connected with a steam turbine and a waste heat boiler to drive power generation; the flue gas outlet of the gas turbine is in communication with the flue gas inlet of the waste heat boiler; the power generation system further comprises a molten carbonate electrolyzer, a concrete heat accumulator and a fuel storage; a first heat exchanger is arranged in series on the pipeline between the flue gas outlet of the waste heat boiler and the cathode inlet of the molten carbonate electrolyzer. The power generation system coupled with a molten carbonate electrolyzer of the combined cycle unit of the embodiments of the present disclosure can reduce the natural gas fuel required by the combined cycle unit, and after separating the carbon dioxide, it is recycled to the waste heat boiler for enrichment treatment, thereby reducing the emission of carbon dioxide, realizing flue gas circulation and green power generation.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure belong to the technical field of power generation, and particularly relate to a power generation system coupling a combined cycle unit with a molten carbonate electrolyzer. BACKGROUND

[0002] The power industry is trying to move towards low-carbon or carbon-free power in response to various national policies to promote the reduction of carbon-based power and ultimately the transition to renewable energy. In a combined cycle gas turbine (CCGT), the working fluid is first compressed, then burned in the combustion chamber of the gas turbine, and finally the combustion products are expanded in the turbine section to produce mechanical energy converted into electrical energy. The flue gas is used to generate steam in the waste heat boiler, which is expanded in the steam turbine to further generate mechanical and electrical power, and the flue gas discharged from the waste heat boiler is mainly nitrogen, water, oxygen and carbon dioxide. The problem to be solved in the operation of a combined cycle power plant includes the emission of carbon dioxide (CO2) due to the combustion of fossil fuels such as natural gas.

[0003] In order to reduce the release of CO2, a carbon capture and storage (CCS) device is usually used, which functions to capture CO2 from flue gas and store it, usually by injecting CO2 into an underground reservoir. However, because the CO2 content in the flue gas is low (usually 3-4%), a larger absorber is required, with huge investment costs and a large amount of energy consumption.

[0004] In the related art, part of the flue gas is sent to the CCS device, and the other part is recycled as a working fluid. On the one hand, recycling the flue gas increases the temperature of the working fluid and reduces its oxygen content, which can have a negative impact. On the other hand, renewable power production devices can provide power for CCS flue gas decarbonization, but solar and wind power systems are intermittent and unpredictable, producing power only when there is enough light and wind. SUMMARY

[0005] Embodiments of the present disclosure aim to at least solve one of the technical problems existing in the prior art, and provide a power generation system coupling a combined cycle unit with a molten carbonate electrolyzer.

[0006] Embodiments of the present disclosure provide a power generation system coupling a combined cycle unit with a molten carbonate electrolyzer, the power generation system comprising a power generator, one side of the power generator being connected with a gas turbine for driving power generation, the other side of the power generator being connected with a steam turbine and a waste heat boiler in sequence for driving power generation; a flue gas outlet of the gas turbine being in communication with a flue gas inlet of the waste heat boiler;

[0007] The power generation system further comprises a molten carbonate electrolyzer, a concrete heat accumulator and a fuel reservoir, a first heat exchanger is arranged in series in a pipeline between a flue gas outlet of the waste heat boiler and a cathode inlet of the molten carbonate electrolyzer, and the first heat exchanger is communicated with the concrete heat accumulator;

[0008] The concrete heat accumulator is used for extracting and storing part of steam in the waste heat boiler, and conveying heat absorbed from the part of steam into a pipeline between the molten carbonate electrolyzer and the first heat exchanger; the pipeline between the molten carbonate electrolyzer and the first heat exchanger is further communicated with a steam outlet of the steam turbine;

[0009] The molten carbonate electrolyzer is powered by a renewable energy power generation device, a first anode outlet of the molten carbonate electrolyzer is communicated with a flue gas inlet of the waste heat boiler, and an inlet and an outlet of the fuel reservoir are respectively communicated with a cathode outlet of the molten carbonate electrolyzer and a combustion chamber of the gas turbine.

[0010] Optionally, a second heat exchanger is further arranged in series in the pipeline between the molten carbonate electrolyzer and the first heat exchanger, and the concrete heat accumulator is used for conveying heat absorbed from steam from the waste heat boiler into a pipeline between the molten carbonate electrolyzer and the second heat exchanger;

[0011] The pipeline between the molten carbonate electrolyzer and the second heat exchanger is communicated with the steam outlet of the steam turbine.

[0012] Optionally, the power generation system further comprises a biomass gasification device and a natural gas reforming device;

[0013] The biomass gasification device and the natural gas reforming device are both communicated with the second heat exchanger, and the second heat exchanger is further communicated with an anode inlet of the molten carbonate electrolyzer.

[0014] Optionally, the power generation system further comprises a cleaner;

[0015] An inlet of the cleaner is respectively communicated with the biomass gasification device and the natural gas reforming device, and an outlet of the cleaner is communicated with the second heat exchanger.

[0016] Optionally, the steam turbine comprises a primary cylinder and a secondary cylinder; an inlet of the primary cylinder is connected with the waste heat boiler, and a steam outlet of the primary cylinder is communicated with a pipeline between the molten carbonate electrolyzer and the second heat exchanger;

[0017] The steam outlet of the primary cylinder is further connected with the secondary cylinder, and the secondary cylinder is connected with the generator.

[0018] Optionally, the power generation system further comprises a dryer and a feedwater heat exchanger;

[0019] The inlet and the first outlet of the dryer are in communication with the second anode outlet of the molten carbonate electrolyzer and the inlet of the feedwater heat exchanger respectively, and the first outlet of the feedwater heat exchanger is in communication with the waste heat boiler for heat exchange by the low-temperature feedwater of the waste heat boiler;

[0020] The second outlet of the dryer is in communication with an underground cave, and the second outlet of the feedwater heat exchanger is in communication with the gas turbine.

[0021] Optionally, the power generation system further comprises a natural gas heat exchanger;

[0022] The first inlet of the natural gas heat exchanger is in communication with the second outlet of the feedwater heat exchanger, and the first outlet of the natural gas heat exchanger is in communication with the gas turbine;

[0023] The second inlet of the natural gas heat exchanger is in communication with a liquefied natural gas storage device, and the second outlet of the natural gas heat exchanger is in communication with the fuel reservoir.

[0024] Optionally, the power generation system further comprises a carbon dioxide trap;

[0025] The carbon dioxide trap is connected in series between the waste heat boiler and the first heat exchanger.

[0026] Optionally, the power generation system further comprises a gas pump and a flow meter;

[0027] The gas pump is connected in series between the waste heat boiler and the carbon dioxide trap, and the flow meter is connected in series between the carbon dioxide trap and the first heat exchanger.

[0028] The power generation system of the combined cycle unit coupled with the molten carbonate electrolyzer according to an embodiment of the present disclosure can increase hydrogen production and reduce the required natural gas fuel by integrating the set power generator, gas turbine, steam turbine, waste heat boiler, molten carbonate electrolyzer, concrete heat accumulator, fuel reservoir and first heat exchanger; the molten carbonate battery is powered by a renewable energy power generation device, and the carbon dioxide is separated from the first anode outlet as flue gas circulating in the power generation system, realizing green and low-carbon power generation; the work efficiency of the power generation system is improved by enriching the separated carbon dioxide, thereby reducing the emission of greenhouse gases. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 FIG. 1 is a structural schematic diagram of a power generation system of a combined cycle unit coupled with a molten carbonate electrolyzer according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] In order for those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure is further described in detail below in combination with the drawings and specific embodiments.

[0031] As shown in Figure 1 A power generation system 100 coupling a combined cycle unit with a molten carbonate electrolyzer, the power generation system 100 comprising a generator 110, one side of which is connected with a gas turbine 111 to drive power generation, and the other side of which is connected with a steam turbine 112 and a waste heat boiler 113 in sequence to drive power generation. The flue gas outlet of the gas turbine 111 is in communication with the flue gas inlet of the waste heat boiler 113. The power generation system 100 further comprises a molten carbonate electrolyzer 120, a concrete heat accumulator 130 and a fuel reservoir 140, and a first heat exchanger 140 is arranged in series on the pipeline between the flue gas outlet of the waste heat boiler 113 and the cathode inlet of the molten carbonate electrolyzer 120, and the first heat exchanger 140 is in communication with the concrete heat accumulator 130.

[0032] The concrete heat accumulator 130 is used to extract and store part of the steam in the waste heat boiler 113, and after absorbing the heat in the part of the steam, the part of the steam is delivered into the pipeline between the molten carbonate electrolyzer 120 and the first heat exchanger 140. The pipeline between the molten carbonate electrolyzer 120 and the first heat exchanger 140 is also in communication with the steam outlet of the steam turbine 112. The molten carbonate electrolyzer 120 is powered by a renewable energy power generation device 200, the first anode outlet of the molten carbonate electrolyzer 120 is in communication with the flue gas inlet of the waste heat boiler 113, and the inlet and outlet of the fuel reservoir 140 are in communication with the cathode outlet of the molten carbonate electrolyzer 120 and the combustion chamber of the gas turbine 111, respectively.

[0033] Specifically, as shown in Figure 1 The gas turbine 111 is adapted to drive the generator 110 to generate power. The flue gas inlet of the waste heat boiler 113 is in communication with the flue gas outlet of the gas turbine 111, and is adapted to recover the heat in the flue gas of the gas turbine 111. The steam turbine 112 and the waste heat boiler 113 are connected, and are also adapted to drive the generator 110 to generate power. The flue gas outlet of the waste heat boiler 113 discharges flue gas mixed with CO2, and the flue gas is delivered to the cathode inlet of the molten carbonate electrolyzer 120 through the pipeline between the waste heat boiler 113 and the molten carbonate electrolyzer 120.

[0034] The concrete heat reservoir 130 is responsible for extracting part of the steam in the waste heat boiler 113 for storage, and is capable of absorbing heat from the steam in the waste heat boiler 113 and delivering it to the pipeline between the molten carbonate electrolyzer 120 and the first heat exchanger 140. The medium-pressure steam is extracted from the waste heat boiler 113, and after passing through the concrete heat reservoir 130, becomes low-pressure steam and is discharged. The low-pressure steam is discharged from the steam outlet of the steam turbine 112 into the pipeline between the molten carbonate electrolyzer 120 and the first heat exchanger 140. The flue gas mixed with CO2 is discharged from the flue gas outlet of the waste heat boiler 113, and passes through the first heat exchanger 140 to exchange heat with the steam in the concrete heat reservoir 130. At this time, part of the steam in the concrete heat reservoir 130 enters the pipeline and combines with the flue gas mixed with CO2 to form a high-temperature mixed gas composed of H2O and CO2, so that H2O and CO2 enter the cathode inlet of the molten carbonate electrolyzer 120 as cathode reaction gas at the same time.

[0035] After the high-temperature mixed gas composed of H2O and CO2 enters the molten carbonate electrolyzer 120, under the action of the electric energy provided by the renewable energy power generation device 200, H2O is electrolyzed into H2 and O2, and the existing CO2 is transferred from the cathode to the anode of the molten carbonate electrolyzer 120. Therefore, H2 and a small amount of CH4 are discharged from the cathode outlet of the molten carbonate electrolyzer 120, and the cathode outlet gas enters the fuel reservoir 140, and then enters the combustion chamber of the gas turbine 111 as green low-carbon fuel. CO2 and a small amount of O2 are discharged from the first anode outlet of the molten carbonate electrolyzer 120, and the exhaust gas enters the waste heat boiler 113 through the flue gas inlet of the waste heat boiler 113, and the high-temperature flue gas enriched in CO2 circulates to heat the steam in the waste heat boiler 113.

[0036] It should be noted that the electrolysis mode of the molten carbonate electrolyzer requires high-temperature water, carbon dioxide and electric energy, and carries out a reduction reaction in the fuel electrode to produce hydrogen, and transfers carbon dioxide through carbonate ions (CO3 2- ). The overall reaction of the molten carbonate electrolyzer is represented by the equation: H2O + CO2 (cathode) → H2 + 0.5O2 + CO2 (anode). The molten carbonate electrolyzer has the unique ability to integrate CO2 during operation, so it is easy to capture CO2 by using the molten carbonate electrolyzer to separate CO2 from the exhaust gas and concentrate it.

[0037] The molten carbonate electrolyzer can be set to operate in the range of 600-650℃, without strict flow requirements at its inlet, thus avoiding degradation of the electrodes. The cathode and anode assemblies of the molten carbonate electrolyzer are made of porous lithiated nickel from a porous nickel oxide (NiO) and Cr and / or Al alloy, and the electrolyte porous matrix is made of γ-LiAlO2, with the electrolyte being a eutectic mixture of lithium, potassium and / or sodium carbonate (Li2CO3, K2CO3 and Na2CO3) that remains in liquid state at 650℃. The molten carbonate electrolyzer has a lower power input compared to the low-temperature water electrolyzer, and thus can operate at a lower voltage. In addition, the operating temperature of the molten carbonate electrolyzer is significantly lower than that of the solid oxide steam electrolyzer, and is also safer.

[0038] The power generation system of the combined cycle unit coupled with the molten carbonate electrolyzer of the embodiments of the present disclosure can increase hydrogen production, thus reducing the required natural gas fuel, and enriching the treatment after separating carbon dioxide, improving the working efficiency of the power generation system, thus reducing the emission of greenhouse gases. Since the entire process in the molten carbonate electrolyzer is the electrochemical decomposition of water, with carbon dioxide being transferred from the cathode to the anode, the required power uses renewable energy, and the carbon dioxide is separated from the first anode outlet as the flue gas circulating of the power generation system, realizing green and low-carbon power generation.

[0039] Exemplarily, as shown in Figure 1 The pipeline between the molten carbonate electrolyzer 120 and the first heat exchanger 140 is further connected with the second heat exchanger 150, and the concrete heat accumulator 130 is used to absorb heat from the steam from the waste heat boiler 113 and deliver the heat into the pipeline between the molten carbonate electrolyzer 120 and the second heat exchanger 150. The pipeline between the molten carbonate electrolyzer 120 and the second heat exchanger 150 is in communication with the steam outlet of the steam turbine 112.

[0040] Further, the power generation system 100 further comprises a biomass gasification device 300 and a natural gas reforming device 400. The biomass gasification device 300 and the natural gas reforming device 400 are both in communication with the second heat exchanger 150, and the second heat exchanger 150 is also in communication with the anode inlet of the molten carbonate electrolyzer 120.

[0041] Still further, the steam turbine 112 comprises a primary cylinder 1121 and a secondary cylinder 1122. The inlet of the primary cylinder 1121 is connected with the waste heat boiler 113, and the steam outlet of the primary cylinder 1121 is in communication with the pipeline between the molten carbonate electrolyzer 120 and the second heat exchanger 150. The steam outlet of the primary cylinder 1121 is also connected with the secondary cylinder 1122, and the secondary cylinder 1122 is connected with the generator 110.

[0042] Specifically, such as Figure 1 As shown, by setting up a concrete heat storage tank 130, a portion of the medium-pressure steam from the waste heat boiler 113 is extracted and stored. After passing through the concrete heat storage tank 130, the medium-pressure steam becomes low-pressure steam and is discharged into the pipeline between the molten carbonate electrolyzer 120 and the second heat exchanger 150. The steam turbine 112 includes a first-stage cylinder 1121 and a second-stage cylinder 1122. The first-stage cylinder 1121 receives steam from the waste heat boiler 113 and discharges low-pressure steam through its steam outlet into the pipeline between the molten carbonate electrolyzer 120 and the second heat exchanger 150. The steam outlet of the first-stage cylinder 1121 is also connected to the second-stage cylinder 1122, and the second-stage cylinder 1122 is connected to the generator 110 to drive the generator 110 for power supply.

[0043] Flue gas from the waste heat boiler 113 is fed into the molten carbonate electrolyzer 120 through a pipeline between the waste heat boiler 113 and the molten carbonate electrolyzer 120. During this process, steam exchange occurs in the first heat exchanger 140 and the concrete heat storage tank 130. Simultaneously, biomass undergoes catalytic chemical reactions in the biomass gasification unit 300 and natural gas in the natural gas reforming unit 400, both producing CO and H2 syngas. This syngas, composed of CO, H2, and CH4, is then exchanged with carbon dioxide in the second heat exchanger 150 before being sent to the molten carbonate electrolyzer 120.

[0044] When the high-temperature synthesis gas of CO, H2, and CH4 is sent to the pipeline between the molten carbonate electrolyzer 120 and the second heat exchanger 150, the medium-pressure steam from the waste heat boiler 113 is cooled and depressurized by the concrete heat storage tank 130 to become low-pressure steam. This low-pressure steam is then transported to the pipeline between the molten carbonate electrolyzer 120 and the second heat exchanger 150 and combines with carbon dioxide to form a high-temperature mixture of CO2 and H2O. After entering the cathode of the molten carbonate electrolyzer 120, under the power of electricity provided by the renewable energy power generation device 200, H2O is electrolyzed into H2 and O2, and CO and O2 rapidly react to become CO2. All the CO2 is transferred from the cathode to the anode of the molten carbonate electrolyzer 120. Therefore, H2 and a small amount of CH4 are discharged from the cathode outlet of the molten carbonate electrolyzer 120. The gas from the cathode outlet of the molten carbonate electrolyzer 120 enters the fuel storage tank 140 and then enters the combustion chamber of the gas turbine 111 as fuel. The first anode outlet discharges CO2 and a small amount of O2. The gas from the first anode outlet of the molten carbonate electrolyzer 120 is directly fed into the flue gas inlet of the waste heat boiler 113. The high-temperature flue gas enriched with CO2 is circulated to heat the steam in the waste heat boiler 113.

[0045] It should be noted that the concrete heat accumulator is a concrete block with multiple channels for flowing gas, which is a relatively mature energy device integrating heat exchange and heat storage.

[0046] The power generation system of the combined cycle unit coupled with the molten carbonate electrolyzer of the embodiment of the present disclosure improves the purification of the biomass synthesis gas through the integration of the molten carbonate electrolyzer, and provides a carbon-free fuel power generation system. Since the fuel source is at least partially hydrogen, the carbon dioxide emissions generated are lower than those of burning natural gas regardless of the percentage of hydrogen burned. In addition, the biomass gasification device used in the present disclosure converts biomass residues into renewable energy, which, in combination with the natural gas reforming device, is a configuration using the biomass gas synthesis biofuel process and steam-methane reforming technology, which can reduce the fuel cost of the power generation system and further achieve the effect of energy saving and carbon emission reduction.

[0047] Exemplarily, as shown in Figure 1 The power generation system 100 further comprises a scrubber 500. The inlet of the scrubber 500 is in communication with the biomass gasification device 300 and the natural gas reforming device 400 respectively, and the outlet of the scrubber 500 is in communication with the second heat exchanger 150.

[0048] Specifically, as shown in Figure 1 The catalytic chemical reactions of biomass in the biomass gasification device 300 and natural gas in the natural gas reforming device 400 both generate CO and H2 synthesis gas, which, after removal of H2S and impurities in the scrubber 500, finally forms high-temperature synthesis gas with components of CO, H2 and CH4. The high-temperature synthesis gas, after heat exchange with carbon dioxide in the second heat exchanger 150, is sent into the molten carbonate electrolyzer 120.

[0049] The power generation system of the combined cycle unit coupled with the molten carbonate electrolyzer of the embodiment of the present disclosure can clean and remove impurities from the generated CO and H2 synthesis gas through the scrubber arranged, and finally obtain high-temperature synthesis gas with components of CO, H2 and CH4.

[0050] Exemplarily, as shown in Figure 1 The power generation system 100 further comprises a dryer 160 and a feedwater heat exchanger 161. The inlet and the first outlet of the dryer 160 are in communication with the second anode outlet of the molten carbonate electrolyzer 120 and the inlet of the feedwater heat exchanger 161 respectively, and the first outlet of the feedwater heat exchanger 161 is in communication with the waste heat boiler 113 to exchange heat with the low-temperature feedwater of the waste heat boiler 113. The second outlet of the dryer 160 is in communication with an underground cave, and the second outlet of the feedwater heat exchanger 161 is in communication with the gas turbine 111.

[0051] Specifically, asFigure 1 As shown, the second anode outlet of the molten carbonate electrolyzer 120 also discharges CO2 and a small amount of O2, and after the CO2 and the small amount of O2 are dehydrated by the dryer 160, the CO2 and the small amount of O2 can continue to be heat-exchanged with the low-temperature feed water of the waste heat boiler 113 through the feed water heat exchanger 161, and the cooled CO2 and the small amount of O2 are transported to the gas turbine 111 as the low-temperature intake air of the gas turbine 111. When the molten carbonate electrolyzer 120 is working, water vapor is electrolyzed into hydrogen and oxygen, and at the same time, carbon dioxide is absorbed from flue gas, and can be transported and captured to the underground cave through the second outlet of the dryer 160 for storage.

[0052] The power generation system of the combined cycle unit coupled with the molten carbonate electrolyzer according to the embodiments of the present disclosure enriches carbon dioxide through the first anode outlet, and after the electrolysis product O2 is used to heat the low-temperature feed water of the waste heat boiler, the low-temperature feed water is cooled, and after heat exchange with liquefied natural gas, the low-temperature feed water is cooled again, and then is used as the low-temperature intake air of the gas turbine. Such a flue gas circulation system avoids the problems of excessively high intake air temperature and reduced O2 concentration of the gas turbine.

[0053] Exemplarily, as Figure 1 shown, the power generation system 100 further comprises a natural gas heat exchanger 162. A first inlet of the natural gas heat exchanger 162 is connected to a second outlet of the feed water heat exchanger 161, and a first outlet of the natural gas heat exchanger 162 is connected to the gas turbine 111. A second inlet of the natural gas heat exchanger 162 is connected to a liquefied natural gas storage device 500, and a second outlet of the natural gas heat exchanger 162 is connected to the fuel reservoir 140.

[0054] Specifically, as Figure 1 shown, the CO2 and the small amount of O2 discharged from the second anode outlet of the molten carbonate electrolyzer 120 are dehydrated by the dryer 160, and then continue to be heat-exchanged with the low-temperature feed water of the waste heat boiler 113 through the feed water heat exchanger 161, and the cooled CO2 and O2 heat the liquefied natural gas in the liquefied natural gas storage device 500 through the natural gas heat exchanger 162. The heated liquefied natural gas enters the fuel reservoir 140, and together with the hydrogen in the fuel reservoir 140, enters the combustion chamber of the gas turbine 111 as low-carbon fuel and oxidizing agent for combustion. This is conducive to improving the working efficiency of the power generation system.

[0055] The power generation system of the combined cycle unit coupled with the molten carbonate electrolyzer of the embodiment of the present disclosure utilizes high-temperature steam and carbon dioxide as the cathode reaction gas of the molten carbonate electrolyzer, and utilizes high-temperature biomass gasification synthesis gas and natural gas catalytic reforming gas as the anode reaction gas of the molten carbonate electrolyzer. In the case that the renewable energy power generation device provides electric energy for the molten carbonate electrolyzer, the cathode product is hydrogen and a small amount of methane, and the anode product is carbon dioxide and oxygen. The cathode product serves as green low-carbon fuel for the gas turbine, and the anode product, under the cooling effect of the low-temperature feedwater of the waste heat boiler and liquefied natural gas, serves as the combustion oxidizing atmosphere for the gas turbine, thereby achieving the effect of energy saving and carbon emission reduction.

[0056] As shown in Figure 1 , the power generation system 100 further comprises a carbon dioxide collector 170 (i.e., a CCS device). The carbon dioxide collector 170 is connected in series between the waste heat boiler 113 and the first heat exchanger 140.

[0057] Further, the power generation system 100 further comprises a gas pump 180 and a flow meter 190. The gas pump 180 is connected in series between the waste heat boiler 113 and the carbon dioxide collector 170, and the flow meter 190 is connected in series between the carbon dioxide collector 170 and the first heat exchanger 140.

[0058] Specifically, as shown in Figure 1 , when the carbon dioxide collector 170 is in the standby state, the carbon dioxide collector 170 does not participate in the specific collection work. The flue gas is discharged from the flue gas outlet of the waste heat boiler 113 under the action of the gas pump 180, and sequentially passes through the carbon dioxide collector 170 and the flow meter 190, and is finally sent into the molten carbonate electrolyzer 120. When the carbon dioxide collector 170 is in the standby state, the carbon dioxide collector 170 only plays an intermediate transport role and does not collect carbon dioxide. The flow meter 190 is used to monitor the specific flow of the flue gas.

[0059] As a specific application method example, as shown in Figure 1 , in the case that the renewable energy power generation device 200 is working, the molten carbonate electrolyzer 120 also works, at which time the carbon dioxide collector 170 can be controlled to be in the standby state. When the molten carbonate electrolyzer 120 works, it can electrolyze water vapor into hydrogen and oxygen, and at the same time, absorb carbon dioxide from the flue gas, and transport and collect the carbon dioxide to the underground cave for storage. Among them, the hydrogen serves as the fuel of the gas turbine 111, and the carbon dioxide serves as the inlet gas of the waste heat boiler 113, thereby playing a role of enriching carbon dioxide, which is helpful to improve the working efficiency of the power generation system.

[0060] When the renewable energy power generation device 200 is not working, the molten carbonate electrolyzer 120 also stops working, at this time the carbon dioxide capturer 170 can be controlled to work, the normal flue gas circulation is maintained through the carbon dioxide capturer 170, and the hydrogen-rich natural gas in the fuel reservoir 140 continues to be used as the fuel of the gas turbine 111.

[0061] When the power demand is large during the power consumption peak period (for example, in the morning and evening), because the unit load will also become larger, and the flue gas will also be more, at this time the molten carbonate electrolyzer 120 and the carbon dioxide capturer 170 can be controlled to work simultaneously.

[0062] The application method of the embodiments of the present disclosure can control specific devices to work according to actual needs, which can effectively save energy and avoid unnecessary waste of resources.

[0063] It can be understood that the above implementation is only an exemplary implementation adopted for illustrating the principles of the present disclosure, however, the present disclosure is not limited thereto. Various modifications and improvements can be made by those of ordinary skill in the art without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also considered to be within the protection scope of the present disclosure.

Claims

1. A power generation system for a combined cycle unit coupled with a molten carbonate electrolyzer, characterized in that, The power generation system includes a generator, one side of which is connected to a gas turbine for driving power generation, and the other side is connected in sequence to a steam turbine and a waste heat boiler for driving power generation; the flue gas outlet of the gas turbine is connected to the flue gas inlet of the waste heat boiler. The power generation system also includes a molten carbonate electrolyzer, a concrete heat storage tank, and a fuel storage tank. A first heat exchanger is connected in series on the pipeline between the flue gas outlet of the waste heat boiler and the cathode inlet of the molten carbonate electrolyzer. The first heat exchanger is connected to the concrete heat storage tank. The concrete heat storage tank is used to extract and store a portion of the steam from the waste heat boiler, and to absorb the heat from the steam and transport it to the pipeline between the molten carbonate electrolyzer and the first heat exchanger; the pipeline between the molten carbonate electrolyzer and the first heat exchanger is also connected to the steam outlet of the steam turbine. The molten carbonate electrolyzer is powered by a renewable energy power generation device. The first anode outlet of the molten carbonate electrolyzer is connected to the flue gas inlet of the waste heat boiler. The inlet and outlet of the fuel storage tank are respectively connected to the cathode outlet of the molten carbonate electrolyzer and the combustion chamber of the gas turbine.

2. The power generation system according to claim 1, characterized in that, A second heat exchanger is also connected in series on the pipeline between the molten carbonate electrolyzer and the first heat exchanger. The concrete heat storage tank is used to absorb heat from the steam from the waste heat boiler and then transport it to the pipeline between the molten carbonate electrolyzer and the second heat exchanger. The pipeline between the molten carbonate electrolyzer and the second heat exchanger is connected to the steam outlet of the steam turbine.

3. The power generation system according to claim 2, characterized in that, The power generation system also includes a biomass gasification unit and a natural gas reforming unit; Both the biomass gasification unit and the natural gas reforming unit are connected to the second heat exchanger, which is also connected to the anode inlet of the molten carbonate electrolyzer.

4. The power generation system according to claim 3, characterized in that, The power generation system also includes a cleaner; The inlet of the cleaner is connected to the biomass gasification unit and the natural gas reforming unit, respectively, and the outlet of the cleaner is connected to the second heat exchanger.

5. The power generation system according to claim 2, characterized in that, The steam turbine includes a primary cylinder and a secondary cylinder; the inlet of the primary cylinder is connected to the waste heat boiler, and the steam outlet of the primary cylinder is connected to the pipeline between the molten carbonate electrolyzer and the second heat exchanger. The steam outlet of the first-stage cylinder is also connected to the second-stage cylinder, which is connected to the generator.

6. The power generation system according to any one of claims 1 to 5, characterized in that, The power generation system also includes a dryer and a feedwater heat exchanger; The inlet and first outlet of the dryer are respectively connected to the second anode outlet of the molten carbonate electrolyzer and the inlet of the feedwater heat exchanger. The first outlet of the feedwater heat exchanger is connected to the waste heat boiler so as to exchange heat through the low temperature feedwater of the waste heat boiler. The second outlet of the dryer is connected to an underground cave, and the second outlet of the feedwater heat exchanger is connected to the gas turbine.

7. The power generation system according to claim 6, characterized in that, The power generation system also includes a natural gas heat exchanger; The first inlet of the natural gas heat exchanger is connected to the second outlet of the feedwater heat exchanger, and the first outlet of the natural gas heat exchanger is connected to the gas turbine. The second inlet of the natural gas heat exchanger is connected to the liquefied natural gas storage device, and the second outlet of the natural gas heat exchanger is connected to the fuel storage device.

8. The power generation system according to claim 7, characterized in that, The power generation system also includes a carbon dioxide trap; The carbon dioxide trap is connected in series in the pipeline between the waste heat boiler and the first heat exchanger.

9. The power generation system according to claim 8, characterized in that, The power generation system also includes an air pump and a flow meter; The air pump is connected in series in the pipeline between the waste heat boiler and the carbon dioxide trap, and the flow meter is connected in series in the pipeline between the carbon dioxide trap and the first heat exchanger.

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