RSOC system for improving peak regulation flexibility of coal-fired power plant and operation method thereof

Abstract

The invention relates to the technical field of coal power and hydrogen energy, and discloses an RSOC system for improving the peak regulation flexibility of a coal-fired power plant and an operation method thereof.The coal-fired power plant comprises a boiler subsystem and a steam turbine subsystem, the RSOC system serves as an energy storage device to be coupled with the coal-fired power plant, and an electrolysis mode of the RSOC system is started to store energy when the load of a power grid is in a low ebb; and switching to a power generation mode to release energy in a power grid load peak, adjusting the output power of the coal-fired power plant, and responding to the power grid demand. A coal-fired power plant and an RSOC system are integrated, the structure of the RSOC system is greatly simplified, extracted steam and air passing through an air pre-heater are used as materials, auxiliary parts such as a gas compressor, a recirculation fan, a water pump and an electric heater are omitted, part of hydrogen at an outlet of a fuel electrode is fed into a boiler for blending combustion and stable combustion in an RSOC electrolysis mode, and the energy consumption is reduced. The two-way conversion characteristic of the RSOC system enables the coal-fired power station to more flexibly respond to load changes, and the peak regulation flexibility of the power station is remarkably improved through efficient energy conversion, quick response and a flexible operation mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal power and hydrogen energy, and particularly relates to an RSOC system for improving the peak shaving flexibility of a coal-fired power plant and a running method thereof. BACKGROUND

[0002] Under the background of high proportion of renewable energy and high proportion of power electronic equipment, thermal power units need to change from the main power supply role to supporting and regulating power supply. Renewable energy power generation such as wind energy and solar energy has intermittency and unpredictability, and thermal power units need to be able to quickly adjust the load to balance the power grid, reduce the frequency fluctuation of the power grid, and improve the stability and reliability of the power grid.

[0003] The traditional method for improving the peak shaving flexibility of a coal-fired power plant mainly is to make technical transformation on the steam turbine and the boiler, for example, increasing a bypass system and optimizing the design of the through-flow part of the steam turbine, so as to improve the flexibility of the unit under low load conditions, but there are problems such as poor operation economy and limited regulation range, which are difficult to meet the high requirements of modern power grid on flexibility and economy, in addition, the frequent start-stop and load fluctuation of the thermal power unit increase the overall carbon emission of the system. Therefore, it is urgent to develop a new technology for improving the peak shaving flexibility of a coal-fired power plant.

[0004] The existing Chinese patent with the publication number CN119134407A discloses an RSOC coupled coal-fired power generation system participating in primary frequency modulation and a running method, which comprises a coal-fired power generation unit thermal system and a reversible solid oxide fuel cell (RSOC) coupling system. The invention improves the primary frequency modulation capacity of the coal-fired power generation system to a certain extent by coupling different power generation units and combining the characteristics of fast RSOC power generation speed and flexible operation. However, the flow rate of the extracted main steam has a great influence on the efficiency of the power plant, and the system configuration is complex.

[0005] The existing Chinese patent with the publication number CN111022139A discloses a coal-fired power generation unit coupled with a liquefied air energy storage power generation system, which comprises an air liquefaction energy storage system and an air expansion power generation system. The power generation system of the invention improves the overall frequency modulation level of the power grid to a certain extent, but the liquefied air energy storage system has high requirements for technology and start-up time, and it takes a certain time from start-up to full load operation, the response speed is slow, and it involves complex thermal equipment and processes, so the construction and maintenance costs are high.

[0006] Chinese patent CN 221547054 U discloses a power grid frequency regulation and load ramping system for thermal power heating units. The boiler's output is connected to a high-pressure bypass desuperheater / pressure reducer, a high-pressure cylinder, and a steam pressure balancer. The high-pressure cylinder's input is equipped with a high-pressure cylinder inlet steam regulating valve group. The outputs of both the high-pressure bypass desuperheater / pressure reducer and the high-pressure cylinder are connected to the boiler's input. A connecting valve between the steam pressure balancer and a high-speed, high-efficiency, quick-installation steam turbine is connected in parallel across both ends. This scheme improves the rapid frequency regulation and load ramping performance of thermal power units to some extent through the coupled regulation of the main steam regulation system and the low-pressure cylinder regulation system. However, this system has many regulating components, high operational complexity, and makes it difficult to achieve rapid load adjustment of the thermal power plant in a short time. Summary of the Invention

[0007] To overcome or alleviate one or more of the above-mentioned technical problems, the present invention aims to provide an RSOC system and its operation method that improves the peak-shaving flexibility of coal-fired power plants. Utilizing existing equipment in the coal-fired power plant, the system supplies low-pressure extraction steam from the turbine and high-temperature air from the boiler air preheater to the RSOC system. A small amount of hydrogen products is directly injected through the extraction steam to maintain the reducing atmosphere of the fuel electrode in the RSOC during electrolysis mode. This eliminates the need for all cryogenic auxiliary equipment indispensable in existing independent RSOC systems, such as fans, water pumps, steam generators, and hydrogen circulation pumps, significantly reducing operating equipment costs. The fuel cell stack operates in exothermic mode, with the fuel cell stack outlet stream entering the heat exchanger. The system heats air and steam separately to the stack operating temperature, thus eliminating high-temperature components prone to failure, such as high-temperature electric heaters. It utilizes extracted steam to directly eject unreacted steam, thereby improving the steam conversion rate of the RSOC system and reducing total steam extraction consumption. Even with a lower heat exchange load than an independent RSOC system, an optimized multi-flow plate heat exchanger design further improves heat exchange efficiency, reduces heat loss, decreases heat exchanger area, and increases the outlet oxygen-enriched air temperature. Excess heat from the hydrogen / steam outlet is used to heat the power plant feedwater, and multi-stage adjustments to the extraction steam position enable full-condition energy efficiency and flexible coordinated control of the ejector and the entire system.

[0008] This invention provides the following technical solution:

[0009] On one hand, the present invention provides an RSOC system to improve the peak-shaving flexibility of a coal-fired power plant. The coal-fired power plant includes a boiler subsystem and a turbine subsystem. The RSOC system, as an energy storage device, is coupled to the coal-fired power plant. During periods of low grid load, the RSOC system uses electrolysis mode to convert electrical energy into chemical energy for storage. During periods of high grid load, it switches to generation mode to rapidly convert the stored chemical energy into electrical energy for release, thereby regulating the output power of the coal-fired power plant and responding to grid demand. The coupling between the coal-fired power plant and the RSOC system includes both electrolysis mode and generation mode.

[0010] The electrolysis mode uses the low-pressure extraction steam from the turbine subsystem and the high-temperature air from the boiler subsystem after the air preheater as the heat source to drive the RSOC system. A small amount of hydrogen products are directly ejected from the extraction steam to maintain the reducing atmosphere of the fuel electrode in the RSOC in the electrolysis mode. The RSOC system operates by exothermic operation of the electric stack. The high-temperature oxygen-rich air from the air electrode outlet is sent to the boiler subsystem for combustion assistance, and part of the hydrogen from the fuel electrode outlet is sent to the boiler for co-firing and stable combustion. The high-temperature steam from the low-pressure cylinder of the turbine subsystem is mixed with the fuel side outlet stream of the RSOC system through the ejector (16) and then enters the electric stack for electrolysis to produce hydrogen and store it.

[0011] The power generation mode uses high-temperature air from the boiler subsystem as the air input to the RSOC and stored hydrogen as the fuel input to the RSOC. High-temperature exhaust gas generated by the reactor electrodes is then sent to the boiler for combustion support.

[0012] According to some implementations, the boiler subsystem includes a boiler (1) and an air preheater (2), with the air preheater (2) installed in the flue at the tail end of the boiler (1);

[0013] The turbine subsystem includes a high-pressure cylinder (3), an intermediate-pressure cylinder (4), a low-pressure cylinder (5), a generator (6), a condenser (7), a condensate pump (8), a low-pressure feedwater heater (9), a deaerator (10), a feedwater pump (11), and a high-pressure feedwater regenerative heater (12). The high-pressure cylinder (3) and the intermediate-pressure cylinder (4) are arranged symmetrically. The low-pressure cylinder (5) is located on the other side of the intermediate-pressure cylinder (4) and is coaxially connected to the generator (6). The generator outlets are respectively It is connected to the inverter (30) and the transformer (31); at the same time, the outlet of the low-pressure cylinder is connected to the inlet of the condenser (7), the condensate pump (8) is arranged at the outlet of the condenser, and then the low-pressure feedwater heater (9), deaerator (13), feedwater pump (14) and high-pressure feedwater heater (12) are arranged in sequence; the first valve (13), the second valve (14) and the third valve (15) are respectively arranged on the newly added extraction pipeline branch on the fourth / fifth / sixth stage extraction main pipeline of the turbine subsystem;

[0014] The RSOC system includes an ejector (16), a first three-way mixing valve (17), an electrostatic precipitator (18), a throttle valve (19), a multi-flow plate heat exchanger (20), a fuel cell stack (21), a gas-liquid separator (22), a dryer (23), a hydrogen compressor (24), a hydrogen storage tank (25), a second three-way mixing valve (26), a third three-way mixing valve (27), an inverter (28), and a transformer (29). High-temperature steam from the turbine subsystem passes through the ejector (16), the first three-way mixing valve (17), and the throttle valve (19), and then exchanges heat with the multi-flow plate heat exchanger (20) before being sent to the fuel electrode of the fuel cell stack (21). Subsequently, this stream flows sequentially through the multi-flow plate heat exchanger (20), the second three-way mixing valve (26), and the third three-way mixing valve (27). In series, a small portion of hydrogen is fed into the boiler for co-firing and stable combustion through the second three-way mixing valve (26), while another portion of the stream is connected to the third three-way mixing valve (27). After that, the stream is split, with a small portion connected to the ejector (16) and the majority of the remaining outlet stream connected to the gas-liquid separator (22). The gas-liquid separator (22) is then connected in series with the dryer (23), the hydrogen compressor (24), and the hydrogen storage tank (25). The inverter (28) inlet is connected to the output power generation of the coal-fired power plant, and the outlet is connected to the fuel cell stack (21). The high-temperature air from the boiler subsystem passes through the electrostatic precipitator (18) and then through the multi-flow plate heat exchanger (20) before being sent to the air electrode of the fuel cell stack (21). After that, the high-temperature air is initially cooled by the multi-flow plate heat exchanger (20) before being sent to the boiler (1).

[0015] According to some implementation methods, in electrolysis mode, the RSOC system closes the connection between the first three-way mixing valve (17) and the hydrogen storage tank (25). At this time, the operation mode is as follows: the high-temperature air from the outlet of the air preheater (2) is used as the air-side inlet stream of the RSOC system after passing through the electrostatic precipitator (18); the outlet of the ejector (16) is connected to the throttle valve (19), the outlet of the electrostatic precipitator (18) is connected to the multi-flow plate heat exchanger (20), and then connected to the fuel cell stack (21). The outlet of the fuel cell stack (21) is connected to the multi-flow plate heat exchanger (20), and then enters the boiler body (1); RSOC system The fuel side outlet stream is connected to the second three-way mixing valve (26). A small portion of the hydrogen is sent to the boiler for co-firing and stable combustion through the second three-way mixing valve (26). Another portion of the stream is connected to the third three-way mixing valve (27), and then split. A small portion is connected to the ejector (16), and the majority of the remaining outlet stream is connected to the gas-liquid separator (22). The gas-liquid separator (22) is then connected in series with the dryer (23), the hydrogen compressor (24), and the hydrogen storage tank (25). The inverter (28) inlet is connected to the output power generation of the coal-fired power plant, and the outlet is connected to the fuel cell stack (21).

[0016] According to some implementation methods, in the power generation mode, the RSOC system closes the connection of the three ports of the third three-way mixing valve (27), and the second three-way mixing valve (26) controls the boiler (1) and the multi-flow plate heat exchanger (20) to maintain communication. At this time, the operation mode is as follows: the upper inlet of the first three-way mixing valve (17) is closed, one side inlet is connected to the hydrogen storage tank (25), and its outlet is connected to the throttle valve (19); the electrostatic precipitator (18) is arranged at the air-side inlet of the RSOC system, and the outlets of the electrostatic precipitator (18) and the throttle valve (19) are connected in series with the multi-flow plate heat exchanger (20) and the fuel cell stack (21). The outlet of the fuel cell stack (21) is connected in sequence to the multi-flow plate heat exchanger (20) and the boiler (1).

[0017] On the other hand, the present invention provides an operation method for an RSOC system that improves the peak-shaving flexibility of coal-fired power plants according to the above-mentioned method, the steps of which are as follows:

[0018] In electrolysis mode, the high-temperature air heated by the air preheater (2) passes through the electrostatic precipitator (18) and then enters the multi-flow plate heat exchanger (20) to be heated to the fuel cell stack operating temperature. After that, it is input to the air electrode of the fuel cell stack (21). The fuel cell stack (21) operates in exothermic mode. The high-temperature air at the outlet of the air electrode of the fuel cell stack (21) enters the multi-flow plate heat exchanger (20) for cooling and is then transported to the boiler body (1) as a combustion aid. The high-temperature steam output from the fourth / fifth / sixth stage extraction steam pipe of the low-pressure cylinder of the steam turbine unit of the coal-fired power plant is mixed with the fuel side outlet stream of the RSOC system through the ejector (16). Then, the inlet stream containing a small amount of hydrogen is reduced to the RSOC operating pressure through the throttle valve (19) and enters the multi-flow plate heat exchanger (20) to be heated to the fuel cell stack operating temperature before being input to the fuel cell stack (21). The fuel electrode, the outlet stream of the fuel cell stack (21) enters the multi-flow plate heat exchanger (20) and after preliminary cooling, a small portion of the hydrogen is sent to the boiler (1) for co-firing and stable combustion. Another portion of the stream is connected to the third three-way mixing valve (27) for diversion. A small portion of the stream enters the ejector (16), and the majority of the remaining stream enters the gas-water separator (22) to heat a stream of condensate from the condensate pump of the steam turbine subsystem. After preheating, the condensate is returned to the inlet stream of the deaerator (10). The hydrogen obtained after cooling the hydrogen-containing water vapor is dried by the dryer (23), pressurized by the hydrogen compressor (24), and then stored in the hydrogen storage tank (25). The AC power generated by the steam supplied by the coal-fired power plant unit is converted into DC power by the inverter (28) to provide power to the fuel cell stack (21).

[0019] In power generation mode, high-temperature air from the air preheater (2) is treated by electrostatic precipitator (18) and then used as the air-side inlet stream of the RSOC system. Hydrogen from the hydrogen storage tank (27) is used as the fuel-side inlet stream of the RSOC system in power generation mode. After passing through the throttle valve (19) and being reduced to the RSOC working pressure, it enters the multi-flow plate heat exchanger (20) and is heated to the working temperature of the fuel cell stack (21). After the reaction in the fuel cell stack (21), the high-temperature air electrode tail gas and the high-temperature fuel electrode tail gas are preheated by the multi-flow plate heat exchanger (20). After being pre-cooled, the high-temperature air electrode tail gas is sent into the furnace (1) for hydrogen combustion, and the high-temperature fuel electrode tail gas is sent into the furnace (1) to realize the recovery and reuse of thermal energy.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention provides an RSOC system and its operation method for improving the peak-shaving flexibility of coal-fired power plants. Utilizing existing equipment in the coal-fired power plant, the system supplies low-pressure extracted steam from the turbine and high-temperature air from the boiler air preheater to the RSOC system. A small amount of hydrogen products is directly injected through the extracted steam to maintain the reducing atmosphere of the fuel electrode in the RSOC during electrolysis mode. This eliminates the need for all cryogenic auxiliary equipment, such as fans, water pumps, steam generators, and hydrogen circulation pumps, which are indispensable in existing independent RSOC systems, significantly reducing operating equipment costs. The fuel cell stack operates in exothermic mode; the fuel cell stack outlet stream enters a heat exchanger to heat the air and steam to the stack's operating temperature, thereby achieving... High-temperature components prone to failure, such as high-temperature electric heaters, have been eliminated; unreacted steam is directly ejected using extraction steam, thereby improving the steam conversion rate of the RSOC system and reducing the total steam consumption; based on a heat exchange load lower than that of an independent RSOC system, the optimized design of a multi-flow plate heat exchanger further improves heat exchange efficiency, reduces heat loss, reduces heat exchanger area, and increases outlet flow temperature; in electrolysis mode, a portion of the hydrogen at the fuel electrode outlet is fed into the boiler for co-firing and stable combustion; excess heat from the hydrogen / steam outlet is used to heat the power plant feedwater, and through multi-stage adjustment of the extraction steam position, the energy efficiency and flexible coordinated control of the ejector and the entire system under all operating conditions are achieved. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an RSOC system structure for improving the peak-shaving flexibility of coal-fired power plants, provided as an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of an RSOC system electrolysis mode for improving the peak-shaving flexibility of coal-fired power plants, provided as an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of an RSOC system power generation mode that improves the peak-shaving flexibility of coal-fired power plants, provided as an embodiment of the present invention.

[0025] In the picture:

[0026] 1-Boiler, 2-Air preheater, 3-High-pressure cylinder, 4-Medium-pressure cylinder, 5-Low-pressure cylinder, 6-Generator, 7-Condenser, 8-Condensate pump, 9-Low-pressure feedwater heater, 10-Deaerator, 11-Feedwater pump, 12-High-pressure feedwater heater, 13-First valve, 14-Second valve, 15-Third valve, 16-Ejector, 17-First three-way mixing valve, 18-Electrostatic precipitator, 19-Throttle valve, 20-Multi-flow plate heat exchanger, 21-Electrostatic stack, 22-Gas-water separator, 23-Dryer, 24-Hydrogen compressor, 25-Hydrogen storage tank, 26-Second three-way mixing valve, 27-Third three-way mixing valve, 28-Inverter, 29-Transformer. Detailed Implementation

[0027] This invention provides an RSOC system to enhance the peak-shaving flexibility of coal-fired power plants. It is deeply coupled with existing coal-fired power plants, and because the RSOC system can switch between electrolysis mode and generation mode within minutes, this feature allows the RSOC to rapidly adjust its operating mode when grid load demand changes rapidly.

[0028] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0029] The present invention will be further described below with reference to the accompanying drawings.

[0030] like Figure 1 As shown, this embodiment provides an RSOC system (hereinafter referred to as RSOC system) to improve the peak-shaving flexibility of coal-fired power plants. Existing coal-fired power plants include a boiler subsystem and a turbine subsystem. Specifically, the boiler subsystem includes a boiler 1 and an air preheater 2, with the air preheater 2 installed in the flue gas duct at the tail end of the boiler 1.

[0031] The turbine subsystem includes high-pressure cylinder 3, intermediate-pressure cylinder 4, low-pressure cylinder 5, generator 6, condenser 7, condensate pump 8, low-pressure feedwater heater 9, deaerator 10, feedwater pump 11, high-pressure feedwater regenerative heater 12, first valve 13, second valve 14, and third valve 15. The high-pressure cylinder 3 and intermediate-pressure cylinder 4 of the turbine are arranged symmetrically, and the low-pressure cylinder 5 is arranged on the other side of the intermediate-pressure cylinder 4. It is then coaxially connected to the generator 6. The generator outlet is connected to the inverter 28 and transformer 29 of the RSOC system, respectively. At the same time, the outlet of the low-pressure cylinder is connected to the inlet of the condenser 7. The condensate pump 8 is arranged at the outlet of the condenser. The low-pressure feedwater heater 9, deaerator 10, feedwater pump 11, high-pressure feedwater heater 12, first valve 13, second valve 14, and third valve 15 are arranged in sequence on the newly added extraction pipeline branches on the fourth / fifth / sixth stage extraction steam main pipeline of the turbine subsystem. The first to eighth stages of steam extraction in the turbine subsystem are existing technologies commonly used in power plants, and will not be elaborated here.

[0032] The RSOC system includes an ejector 16, a first three-way mixing valve 17, an electrostatic precipitator 18, a throttle valve 19, a multi-stream plate heat exchanger 20, a fuel cell stack 21, a gas-liquid separator 22, a dryer 23, a hydrogen compressor 24, a hydrogen storage tank 25, a second three-way mixing valve 26, a third three-way mixing valve 27, an inverter 28, and a transformer 29. High-temperature steam from the turbine subsystem passes through the ejector 16, the first three-way mixing valve 17, and the throttle valve 19, then passes through the multi-stream plate heat exchanger 20 for heat exchange before being fed into the fuel electrode of the fuel cell stack 21. This stream is then connected in series with the multi-stream plate heat exchanger 20, the second three-way mixing valve 26, and the third three-way mixing valve 27. A small portion of the hydrogen is fed into the boiler for co-firing and stable combustion via the second three-way mixing valve 26, while another portion is connected to the third three-way mixing valve 27. Afterward, the stream is split, with a small portion connected to the ejector 16, and the remainder... Most of the outbound logistics are connected to the gas-liquid separator 22, which is then connected in series with the dryer 23, the hydrogen compressor 24, and the hydrogen storage tank 25. The inlet of the inverter 28 is connected to the output power generation of the coal-fired power plant, and the outlet is connected to the fuel cell stack 21. The high-temperature air from the boiler subsystem passes through the electrostatic precipitator 18 and then through the multi-flow plate heat exchanger 20 before being sent to the air electrode of the fuel cell stack 21. After that, the high-temperature air is initially cooled by the multi-flow plate heat exchanger 20 before being sent to the boiler.

[0033] After being coupled with a coal-fired power plant system, the RSOC system is greatly simplified. All components in a conventional RSOC system, such as fans, pumps, steam generators, gas preheaters, exhaust gas cooling, and high-temperature electric heating, are eliminated, significantly reducing system investment costs and greatly improving system operational reliability and load-bearing capacity.

[0034] like Figure 2As shown, in the RSOC system electrolysis mode, the connection between the first three-way mixing valve 17 and the hydrogen storage tank 25 is closed. The operating mode at this time is as follows: the high-temperature air from the air preheater 2 outlet passes through the electrostatic precipitator 18 and becomes the air-side inlet stream of the RSOC system. The ejector 16 outlet is connected to the throttle valve 19, and the electrostatic precipitator 18 outlet is connected to the multi-flow plate heat exchanger 20, which is then connected to the fuel cell stack 21. The fuel cell stack 21 outlet is connected to the multi-flow plate heat exchanger 20 and then enters the boiler 1. The RSOC system fuel-side outlet stream is connected to the second three-way mixing valve 26. A small portion of the hydrogen is sent to the boiler for co-firing and stable combustion through the second three-way mixing valve 26, while another portion is connected to the third three-way mixing valve 27. Afterward, the stream is split, with a small portion connected to the ejector 16 and the majority of the outlet stream on the right side connected to the gas-liquid separator 22. After the separator, it is connected in series with the dryer 23, the hydrogen compressor 24, and the hydrogen storage tank 25. The inverter 28 inlet is connected to the coal-fired power plant, and the outlet is connected to the fuel cell stack 21.

[0035] like Figure 3 As shown, in the RSOC system power generation mode, the connections of the three ports of the third three-way mixing valve 27 are completely closed, and the second three-way mixing valve 26 controls the connection between the boiler 1 and the multi-flow plate heat exchanger 20. At this time, the operation mode is as follows: the upper inlet of the first three-way mixing valve 17 is closed, its right inlet is connected to the hydrogen storage tank 25, and its outlet is connected to the throttle valve 19. The electrostatic precipitator 18 is arranged at the air-side inlet of the RSOC system. The outlets of the electrostatic precipitator 18 and the throttle valve 19 are connected in series with the multi-flow plate heat exchanger 20 and the fuel cell stack 21. The outlet of the fuel cell stack 21 is connected in sequence to the multi-flow plate heat exchanger 20 and the boiler 1.

[0036] As an energy storage device, the RSOC system is coupled with a coal-fired power plant. During periods of low grid load, the RSOC system uses electrolysis to convert electrical energy into chemical energy for storage. During periods of high grid load, it switches to generation mode to quickly convert the stored chemical energy into electrical energy for release, thereby regulating the output power of the coal-fired power plant and responding quickly to grid demand.

[0037] The operating method of the RSOC system for improving the peak-shaving flexibility of coal-fired power plants in this embodiment is as follows:

[0038] like Figure 2 As shown, in the electrolysis mode of the RSOC system, the flow of system components is as follows:

[0039] In the boiler subsystem, air is heated to high temperature by the air preheater 2, then passes through the electrostatic precipitator 18 and enters the multi-flow plate heat exchanger 20 to be heated to the fuel cell stack operating temperature. It is then fed to the air electrode of the fuel cell stack 21, which operates in exothermic mode. The high-temperature air from the air electrode outlet of the fuel cell stack 21 is cooled in the multi-flow plate heat exchanger 20 and then sent to the boiler body 1 as a combustion aid. High-temperature steam output from the fourth / fifth / sixth stage extraction steam pipes of the low-pressure cylinder in the turbine subsystem is mixed with the fuel-side outlet stream of the RSOC system via the ejector 16, replacing the conventional electrolysis mode. The hydrogen premixing process reduces the need for components such as recirculation fans, further improving system fuel utilization. The inlet stream containing a small amount of hydrogen is then reduced to the RSOC working pressure via throttle valve 19 before entering a multi-flow plate heat exchanger 20 to be heated to the fuel cell stack's operating temperature. It is then fed to the fuel electrodes of fuel cell stack 21. The outlet stream from fuel cell stack 21 enters the multi-flow plate heat exchanger 20 for preliminary cooling before entering a gas-liquid separator 22 to heat a stream of condensate from the turbine subsystem's condensate pump. This preheated condensate is then returned to the deaerator 10 inlet stream. The hydrogen obtained from the cooled hydrogen-containing steam stream is dried sequentially by dryer 23, pressurized by hydrogen compressor 24, and then stored in hydrogen storage tank 25. The AC power generated by the coal-fired power plant unit after steam supply is converted to DC power by inverter 28 to provide power to fuel cell stack 21.

[0040] like Figure 3 As shown, in power generation mode, the flow of system components is as follows:

[0041] High-temperature air from air preheater 2 is used as the air-side inlet stream of the RSOC system after passing through electrostatic precipitator 18. Hydrogen from hydrogen storage tank 27 in electrolysis mode is used as the fuel-side inlet stream of the RSOC system in power generation mode. After passing through throttle valve 19 to reduce the RSOC working pressure, it enters multi-flow plate heat exchanger 20 and is heated to the working temperature of fuel cell stack 21. After the reaction in fuel cell stack 21, the high-temperature air electrode tail gas (mainly composed of water vapor and hydrogen) and the high-temperature fuel electrode tail gas are preheated by multi-flow plate heat exchanger 20. After preliminary cooling, the high-temperature air electrode tail gas is sent to boiler 1 for hydrogen combustion, and the high-temperature fuel electrode tail gas is sent to boiler 1 to realize the recovery and reuse of heat energy.

[0042] The first valve 13, the second valve 14, and the third valve 15 of the system are respectively arranged on the newly added extraction branch pipes on the fourth / fifth / sixth stage extraction steam main pipes of the steam turbine subsystem. As the fuel-side inlet logistics in the electrolysis mode of the RSOC system, a flexible extraction steam strategy is adopted to reduce system energy loss.

[0043] After being coupled with a coal-fired power plant system, the RSOC system is greatly simplified. All components in a conventional RSOC system, such as fans, pumps, steam generators, gas preheaters, tail gas coolers, and high-temperature electric heaters, are eliminated, significantly reducing system investment costs and greatly improving system operational reliability and load-bearing capacity.

[0044] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A RSOC system for improving the peak-shaving flexibility of a coal-fired power plant, the coal-fired power plant comprising a boiler subsystem and a turbine subsystem, characterized in that, The RSOC system, acting as an energy storage device, is coupled with the coal-fired power plant. During periods of low grid load, the RSOC system uses electrolysis mode to convert electrical energy into chemical energy for storage. During periods of high grid load, it switches to power generation mode to rapidly convert the stored chemical energy into electrical energy for release, thereby regulating the output power of the coal-fired power plant and responding to grid demand. The coupling between the coal-fired power plant and the RSOC system includes both electrolysis and power generation modes. The electrolysis mode uses the low-pressure extraction steam from the turbine subsystem and the high-temperature air from the boiler subsystem after the air preheater as the heat source to drive the RSOC system. A small amount of hydrogen products are directly ejected from the extraction steam to maintain the reducing atmosphere of the fuel electrode in the RSOC in the electrolysis mode. The RSOC system operates by exothermic operation of the electric stack. The high-temperature oxygen-rich air from the air electrode outlet is sent to the boiler subsystem for combustion assistance, and part of the hydrogen from the fuel electrode outlet is sent to the boiler for co-firing and stable combustion. The high-temperature steam from the low-pressure cylinder of the turbine subsystem is mixed with the fuel side outlet stream of the RSOC system through the ejector (16) and then enters the electric stack for electrolysis to produce hydrogen and store it. The power generation mode uses high-temperature air from the boiler subsystem as the air input to the RSOC and stored hydrogen as the fuel input to the RSOC. High-temperature exhaust gas generated by the reactor electrodes is then sent to the boiler for combustion support.

2. The RSOC system for improving the peak-shaving flexibility of coal-fired power plants according to claim 1, characterized in that, The boiler subsystem includes a boiler (1) and an air preheater (2), with the air preheater (2) installed in the flue at the tail end of the boiler (1). The turbine subsystem includes a high-pressure cylinder (3), an intermediate-pressure cylinder (4), a low-pressure cylinder (5), a generator (6), a condenser (7), a condensate pump (8), a low-pressure feedwater heater (9), a deaerator (10), a feedwater pump (11), and a high-pressure feedwater regenerative heater (12). The high-pressure cylinder (3) and the intermediate-pressure cylinder (4) are arranged symmetrically. The low-pressure cylinder (5) is located on the other side of the intermediate-pressure cylinder (4) and is coaxially connected to the generator (6). The generator outlets are respectively It is connected to the inverter (30) and the transformer (31); at the same time, the outlet of the low-pressure cylinder is connected to the inlet of the condenser (7), the condensate pump (8) is arranged at the outlet of the condenser, and then the low-pressure feedwater heater (9), deaerator (13), feedwater pump (14) and high-pressure feedwater heater (12) are arranged in sequence; the first valve (13), the second valve (14) and the third valve (15) are respectively arranged on the newly added extraction pipeline branch on the fourth / fifth / sixth stage extraction main pipeline of the turbine subsystem; The RSOC system includes an ejector (16), a first three-way mixing valve (17), an electrostatic precipitator (18), a throttle valve (19), a multi-flow plate heat exchanger (20), a fuel cell stack (21), a gas-liquid separator (22), a dryer (23), a hydrogen compressor (24), a hydrogen storage tank (25), a second three-way mixing valve (26), a third three-way mixing valve (27), an inverter (28), and a transformer (29). High-temperature steam from the turbine subsystem passes through the ejector (16), the first three-way mixing valve (17), and the throttle valve (19), and then exchanges heat with the multi-flow plate heat exchanger (20) before being sent to the fuel electrode of the fuel cell stack (21). Subsequently, this stream flows sequentially through the multi-flow plate heat exchanger (20), the second three-way mixing valve (26), and the third three-way mixing valve (27). In series, a small portion of hydrogen is fed into the boiler for co-firing and stable combustion through the second three-way mixing valve (26), while another portion of the stream is connected to the third three-way mixing valve (27). After that, the stream is split, with a small portion connected to the ejector (16) and the majority of the remaining outlet stream connected to the gas-liquid separator (22). The gas-liquid separator (22) is then connected in series with the dryer (23), the hydrogen compressor (24), and the hydrogen storage tank (25). The inverter (28) inlet is connected to the output power generation of the coal-fired power plant, and the outlet is connected to the fuel cell stack (21). The high-temperature air from the boiler subsystem passes through the electrostatic precipitator (18) and then through the multi-flow plate heat exchanger (20) before being sent to the air electrode of the fuel cell stack (21). After that, the high-temperature air is initially cooled by the multi-flow plate heat exchanger (20) before being sent to the boiler (1).

3. The RSOC system for improving the peak-shaving flexibility of coal-fired power plants according to claim 2, characterized in that, In electrolysis mode, the RSOC system closes the connection between the first three-way mixing valve (17) and the hydrogen storage tank (25). The operating mode is as follows: the high-temperature air from the air preheater (2) is treated by the electrostatic precipitator (18) and then used as the air-side inlet stream of the RSOC system; the outlet of the ejector (16) is connected to the throttle valve (19), the outlet of the electrostatic precipitator (18) is connected to the multi-flow plate heat exchanger (20), and then to the fuel cell stack (21); the outlet of the fuel cell stack (21) is connected to the multi-flow plate heat exchanger (20), and then enters the boiler body (1); the fuel side of the RSOC system... The outflow stream is connected to the second three-way mixing valve (26). A small portion of the hydrogen is fed into the boiler for co-firing and stable combustion through the second three-way mixing valve (26). Another portion of the stream is connected to the third three-way mixing valve (27), and then splits. A small portion is connected to the ejector (16), and the majority of the outflow stream is connected to the gas-liquid separator (22). The gas-liquid separator (22) is then connected in series with the dryer (23), the hydrogen compressor (24), and the hydrogen storage tank (25). The inverter (28) inlet is connected to the output power generation of the coal-fired power plant, and the outlet is connected to the fuel cell stack (21).

4. The RSOC system for improving the peak-shaving flexibility of coal-fired power plants according to claim 2, characterized in that, In power generation mode, the RSOC system closes the connection of the three ports of the third three-way mixing valve (27), and the second three-way mixing valve (26) controls the boiler (1) and the multi-flow plate heat exchanger (20) to maintain communication. At this time, the operation mode is as follows: the upper inlet of the first three-way mixing valve (17) is closed, one side inlet is connected to the hydrogen storage tank (25), and its outlet is connected to the throttle valve (19); the electrostatic precipitator (18) is arranged at the air-side inlet of the RSOC system. The outlets of the electrostatic precipitator (18) and the throttle valve (19) are connected in series with the multi-flow plate heat exchanger (20) and the fuel cell stack (21). The outlet of the fuel cell stack (21) is connected in sequence to the multi-flow plate heat exchanger (20) and the boiler (1).

5. An operation method for an RSOC system for improving the peak-shaving flexibility of a coal-fired power plant according to any one of claims 2 to 4, characterized in that: In electrolysis mode, the high-temperature air heated by the air preheater (2) passes through the electrostatic precipitator (18) and then enters the multi-flow plate heat exchanger (20) to be heated to the fuel cell stack operating temperature. After that, it is input to the air electrode of the fuel cell stack (21). The fuel cell stack (21) operates in exothermic mode. The high-temperature air at the outlet of the air electrode of the fuel cell stack (21) enters the multi-flow plate heat exchanger (20) for cooling and is then transported to the boiler body (1) as a combustion aid. The high-temperature steam output from the fourth / fifth / sixth stage extraction steam pipe of the low-pressure cylinder of the steam turbine unit of the coal-fired power plant is mixed with the fuel side outlet stream of the RSOC system through the ejector (16). Then, the inlet stream containing a small amount of hydrogen is reduced to the RSOC operating pressure through the throttle valve (19) and enters the multi-flow plate heat exchanger (20) to be heated to the fuel cell stack operating temperature before being input to the fuel cell stack (21). The fuel electrode, the outlet stream of the fuel cell stack (21) enters the multi-flow plate heat exchanger (20) and after preliminary cooling, a small portion of the hydrogen is sent to the boiler (1) for co-firing and stable combustion. Another portion of the stream is connected to the third three-way mixing valve (27) for diversion. A small portion of the stream enters the ejector (16), and the majority of the remaining stream enters the gas-water separator (22) to heat a stream of condensate from the condensate pump of the steam turbine subsystem. After preheating, the condensate is returned to the inlet stream of the deaerator (10). The hydrogen obtained after cooling the hydrogen-containing water vapor is dried by the dryer (23), pressurized by the hydrogen compressor (24), and then stored in the hydrogen storage tank (25). The AC power generated by the steam supplied by the coal-fired power plant unit is converted into DC power by the inverter (28) to provide power to the fuel cell stack (21). In power generation mode, high-temperature air from the air preheater (2) is used as the air-side inlet stream of the RSOC system after passing through the electrostatic precipitator (18). Hydrogen from the hydrogen storage tank (27) is used as the fuel-side inlet stream of the RSOC system in power generation mode. After passing through the throttle valve (19) to reduce the RSOC working pressure, it enters the multi-flow plate heat exchanger (20) and is heated to the working temperature of the fuel cell stack (21). After the reaction in the fuel cell stack (21), the high-temperature air electrode tail gas and the high-temperature fuel electrode tail gas are preheated by the multi-flow plate heat exchanger (20). After preliminary cooling, the high-temperature air electrode tail gas is sent into the furnace (1) for hydrogen combustion, and the high-temperature fuel electrode tail gas is sent into the furnace (1) to realize the recovery and reuse of thermal energy.

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