Reversible fuel cell coupling coal power unit peak shaving system and method

Abstract

The invention provides a reversible fuel cell coupling coal power unit peak shaving system and method. The system comprises a coal-fired boiler, a steam turbine, a power generator and a reversible fuel cell. A steam outlet of the coal-fired boiler is connected with an inlet of the reversible fuel cell; an outlet of the reversible fuel cell is connected with a steam inlet of the steam turbine; in the power grid load valley period, high-temperature steam generated by the coal-fired boiler is conveyed to the reversible fuel cell, the power generator supplies power to the reversible fuel cell, and the reversible fuel cell electrolyzes the high-temperature steam in an electrolysis mode to generate hydrogen and oxygen; in a power grid load peak period, hydrogen and oxygen generated by electrolysis of the reversible fuel cell enter the reversible fuel cell, the reversible fuel cell reacts the hydrogen and the oxygen to generate high-temperature steam and direct current in a power generation mode, the generated high-temperature steam enters the steam turbine to do work and generate power, and the generated direct current is supplied to a power grid. The system improves the efficiency of a coupling system, improves the flexibility of a power grid, promotes the consumption of renewable energy sources, and reduces the carbon emission.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal-fired power generation unit peak regulation, and in particular relates to a reversible fuel cell coupled coal-fired power generation unit peak regulation system and method. Background Art

[0002] With the rapid increase in the proportion of renewable energy (wind power, photovoltaic power) in the power system, the volatility of the power grid has increased significantly. Coal-fired power units, as traditional baseload power sources, need to assume more peak-shaving responsibilities to balance supply and demand and ensure the stability of the power grid. However, coal-fired power units face problems such as reduced efficiency, increased coal consumption, and equipment wear when operating at low loads, and usually need to improve peak-shaving capabilities through flexibility transformation. Reversible Solid Oxide Fuel Cell (R-SOFC) is a bidirectional energy conversion device that can generate electricity in fuel cell (FC) mode and produce hydrogen (or synthesis gas) in electrolyzer (EC) mode. It combines the functions of solid oxide fuel cells (SOFC) and solid oxide electrolyzers (SOECs), has high efficiency, fuel flexibility and energy storage potential, and is an important part of the flexible peak-shaving energy system.

[0003] Flexible peaking of coal-fired power generation is a key technology during the transition period of energy transformation. It requires achieving safe, economical, and low-carbon deep peaking through combustion optimization, thermal transformation, intelligent control, and multi-energy coupling. In the future, as the proportion of renewable energy increases, coal-fired power will gradually shift to a flexible backup power source. However, reversible solid oxide fuel cells have not yet been used for energy storage and peaking of coal-fired power generation.

[0004] Reversible solid oxide fuel cell (R-SOFC): can switch between power generation (FC mode) and hydrogen production by electrolysis (EC mode), with high efficiency (>80%) and flexible fuel, but the cost of single operation is relatively high.

[0005] Existing coal-fired power coupling technology solutions mostly use steam extraction to produce hydrogen or heat storage, but the peak regulation range is limited.

[0006] In view of the above problems, it is necessary to propose a reversible fuel cell coupled coal-fired power unit peak-shaving system and method that is reasonably designed and effectively solves the above problems. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art and provide a reversible fuel cell coupled coal-fired power unit peak regulation system and method.

[0008] The present invention provides a reversible fuel cell coupled coal-fired power unit peak regulation system, comprising a coal-fired boiler, a steam turbine, a generator and a reversible fuel cell;

[0009] The steam outlet of the coal-fired boiler is connected to the inlet of the reversible fuel cell, and the outlet of the reversible fuel cell is connected to the steam inlet of the steam turbine; wherein,

[0010] During a low-load period of the power grid, the high-temperature steam generated by the coal-fired boiler is delivered to the reversible fuel cell, and the generator supplies power to the reversible fuel cell, so that the reversible fuel cell performs a water electrolysis reaction on the high-temperature steam in an electrolysis mode to produce hydrogen and oxygen;

[0011] During peak load periods of the power grid, hydrogen and oxygen generated by electrolysis in the reversible fuel cell enter the reversible fuel cell, and the reversible fuel cell reacts the hydrogen and oxygen to produce high-temperature steam and direct current in the power generation mode. The high-temperature steam generated enters the steam turbine to generate power, and the generated direct current is used to supply the power grid.

[0012] Optionally, the system further comprises a heat exchange device;

[0013] The heat exchange device is arranged close to the reversible fuel cell; wherein,

[0014] The inlet of the heat exchange device is connected to the flue gas outlet of the coal-fired boiler, and the outlet of the heat exchange device is connected to the flue gas inlet of the coal-fired boiler;

[0015] The heat exchange device is used to receive the high-temperature flue gas from the coal-fired boiler to maintain the reversible fuel cell in a high-temperature state.

[0016] Optionally, the system further includes an AC / DC inverter;

[0017] The AC / DC inverter is arranged between the reversible fuel cell and the generator, and is used for mutual conversion between direct current and alternating current.

[0018] Optionally, the system further includes a load control center;

[0019] The load control center is connected to the output end of the generator and the output end of the AC / DC inverter respectively, and is used to distribute electric energy to the power grid according to the load state of the power grid.

[0020] Optionally, the system further comprises a gas separation device;

[0021] The inlet of the gas separation device is connected to the outlet of the reversible fuel cell, and is used to separate hydrogen and oxygen generated by electrolysis of the reversible fuel cell.

[0022] Optionally, the system further comprises a hydrogen storage device;

[0023] The inlet of the hydrogen storage device is connected to the first outlet of the gas separation device.

[0024] Optionally, the system further comprises an oxygen storage device;

[0025] The inlet of the oxygen storage device is connected to the second outlet of the gas separation device.

[0026] Optionally, the reversible fuel cell is a reversible solid oxide fuel cell.

[0027] Another aspect of the present invention provides a reversible fuel cell coupled coal-fired power generation unit peak shaving method, which uses the reversible fuel cell coupled coal-fired power generation unit peak shaving system described above; wherein the method comprises:

[0028] During a low-load period of the power grid, the high-temperature steam generated by the coal-fired boiler is delivered to the reversible fuel cell, and the generator supplies power to the reversible fuel cell, so that the reversible fuel cell performs a water electrolysis reaction on the high-temperature steam in an electrolysis mode to produce hydrogen and oxygen;

[0029] During peak load periods of the power grid, hydrogen and oxygen generated by electrolysis in the reversible fuel cell enter the reversible fuel cell, and the reversible fuel cell reacts the hydrogen and oxygen to produce high-temperature steam and direct current in the power generation mode. The high-temperature steam generated enters the steam turbine to generate power, and the generated direct current is used to supply the power grid.

[0030] The reversible fuel cell coupled coal-fired power unit peak shaving system and method of the disclosed embodiment realizes bidirectional conversion of electricity to hydrogen through the bidirectional regulation capability of the reversible fuel cell, has the functions of energy storage and load regulation, and can quickly adjust the output load of the coal-fired power unit through rapid electricity-hydrogen conversion. At the same time, it can further improve the lower limit of the unit's output and increase the deep peak shaving benefit of the unit. In addition, the reversible fuel cell can use the high-temperature flue gas of the coal-fired boiler in the electrolysis mode to improve the electrolysis efficiency, and the high-temperature steam generated in the power generation mode can go to the steam turbine to participate in power generation, effectively improving the thermal efficiency of the system. This system not only improves the rate of load increase and decrease of the coal-fired unit and increases the lower limit of the unit's output, but also improves the thermal efficiency of the system through the coordinated processing of heat exchange, which is of great significance and value to the flexible peak shaving of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure is a schematic structural diagram of a reversible fuel cell coupled coal-fired power generation unit peak-shaving system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0033] like Figure 1As shown, one aspect of the present invention provides a reversible fuel cell coupled coal-fired power unit peak shaving system, which includes a coal-fired boiler 1, a steam turbine 2, a generator 3, and a reversible fuel cell 4. The coal-fired boiler 1, steam turbine 2, and generator 3 are connected in sequence. The coal-fired boiler 1 generates steam to drive the steam turbine 2, which in turn drives the generator 3 to rotate and generate electricity.

[0034] The steam outlet of the coal-fired boiler 1 is connected to the inlet of the reversible fuel cell 4, and the outlet of the reversible fuel cell 4 is connected to the steam inlet of the steam turbine 2. During the low load period of the power grid, the high-temperature steam generated by the coal-fired boiler 1 is transported to the reversible fuel cell 4, and the generator 3 supplies power to the reversible fuel cell 4, so that the reversible fuel cell 4 can electrolyze the high-temperature steam to produce hydrogen and oxygen in the electrolysis mode.

[0035] It should be noted that, in this embodiment, the reversible fuel cell 4 may be a reversible solid oxide fuel cell.

[0036] During the peak load period of the power grid, the hydrogen and oxygen generated by electrolysis of the reversible fuel cell 4 enter the reversible fuel cell 4. The reversible fuel cell 4 synthesizes the hydrogen and oxygen to produce high-temperature steam and direct current in the power generation mode. The high-temperature steam generated enters the steam turbine 2 to generate work and the generated direct current is used to supply the power grid.

[0037] The reversible fuel cell of the disclosed embodiment is coupled with the peak-shaving system of the coal-fired power unit. Through the bidirectional regulation capability of the reversible fuel cell, the bidirectional conversion of electricity to hydrogen is realized. It has the functions of energy storage and load regulation. The output load of the coal-fired power unit is quickly adjusted through the rapid conversion of electricity to hydrogen. At the same time, it can further improve the lower limit of the output of the unit and improve the deep peak-shaving benefit of the unit. In addition, the reversible fuel cell can use the high-temperature flue gas of the coal-fired boiler to improve the electrolysis efficiency in the electrolysis mode, and the high-temperature steam generated in the power generation mode can go to the steam turbine to participate in power generation, effectively improving the thermal efficiency of the system. This system not only improves the rate of load increase and decrease of the coal-fired unit and increases the lower limit of the output of the unit, but also improves the thermal efficiency of the system through the coordinated processing of heat exchange, which is of great significance and value to the flexible peak-shaving of the unit; through the synergy of heat-electricity-hydrogen, the flue gas and steam of the coal-fired power unit are used to improve the electrolysis efficiency and heat utilization efficiency of the reversible fuel cell, realizing a zero-carbon cycle.

[0038] For example, Figure 1 As shown, the system further includes a heat exchange device 5; the heat exchange device 5 is arranged close to the reversible fuel cell 4; wherein, the inlet of the heat exchange device 5 is connected to the flue gas outlet of the coal-fired boiler 1, and the outlet of the heat exchange device 5 is connected to the flue gas inlet of the coal-fired boiler 1.

[0039] The heat exchange device 5 is used to receive the high-temperature flue gas from the coal-fired boiler 1 to maintain the reversible fuel cell 4 in a high-temperature state.

[0040] Specifically, part of the high-temperature flue gas generated by the coal-fired boiler 1 can be extracted and transported to the heat exchange device 5 for heat exchange and then returned to the coal-fired boiler 1. The high-temperature flue gas enters the heat exchange device 5 for heat exchange, which can maintain the reversible fuel cell 4 in a high-temperature state, so that the reversible fuel cell 4 has a higher reaction efficiency at high temperature.

[0041] For example, Figure 1 As shown, the system further includes an AC-DC inverter 6 , which is disposed between the reversible fuel cell 4 and the generator 3 and is used for mutual conversion between direct current and alternating current.

[0042] Specifically, during the off-peak period of the grid load, the reversible fuel cell 4 is in the electrolysis mode, and the AC power output by the generator 3 is converted into DC power by the AC / DC inverter 6 to power the water electrolysis reaction of the reversible fuel cell 4 .

[0043] During peak load periods of the power grid, the reversible fuel cell 4 in power generation mode converts the DC power generated by the synthesis reaction of hydrogen and oxygen into AC power through the AC / DC inverter 6 and then supplies it to the power grid.

[0044] For example, Figure 1 As shown, the system further includes a load control center 7; the load control center 7 is connected to the output end of the generator 3 and the output end of the AC / DC inverter 6 respectively, and is used to distribute electric energy to the grid according to the load state of the grid.

[0045] Specifically, during the off-peak period of the grid load, the reversible fuel cell 4 is in electrolysis mode, and the load control center 7 converts the AC power generated by the generator 3 into DC power through the AC / DC inverter 6 to power the water electrolysis reaction of the reversible fuel cell 4.

[0046] During peak load periods of the power grid, the DC power generated by the reversible fuel cell 4 in power generation mode is converted into AC power by the AC / DC inverter 6 and transmitted to the load control center 7. The load control center 7 combines the AC power with the AC power generated by the generator 3 and supplies it to the power grid.

[0047] For example, Figure 1 As shown, the system further includes a gas separation device; the inlet of the gas separation device is connected to the outlet of the reversible fuel cell 4, and is used to separate the hydrogen and oxygen generated by electrolysis of the reversible fuel cell 4.

[0048] Specifically, the mixed gas of hydrogen and oxygen generated by the electrolysis of water by the reversible fuel cell 4 in the electrolysis mode enters the gas separation device, and the hydrogen and oxygen are separated by the gas separation device.

[0049] For example, Figure 1 As shown, the system further includes a hydrogen storage device 8; the inlet of the hydrogen storage device 8 is connected to the first outlet of the gas separation device.

[0050] Specifically, the hydrogen generated by the electrolysis of water by the reversible fuel cell 4 in the electrolysis mode enters the hydrogen storage device 8 for storage. When the reversible fuel cell 4 is in the power generation mode, the hydrogen in the hydrogen storage device 8 is transported back to the reversible fuel cell 4.

[0051] For example, Figure 1 As shown, the system further includes an oxygen storage device 9; the inlet of the oxygen storage device 9 is connected to the second outlet of the gas separation device.

[0052] Specifically, the oxygen generated by the electrolysis of water by the reversible fuel cell 4 in the electrolysis mode enters the oxygen storage device 9 for storage. When the reversible fuel cell 4 is in the power generation mode, the oxygen in the oxygen storage device 9 is transported back to the reversible fuel cell 4.

[0053] Another aspect of the present invention provides a reversible fuel cell coupled coal-fired power unit peak-shaving method, which adopts the reversible fuel cell coupled coal-fired power unit peak-shaving system described above. The specific structural features of the reversible fuel cell coupled coal-fired power unit peak-shaving system have been described in detail above and will not be repeated here.

[0054] The peak-shaving method of a reversible fuel cell coupled coal-fired power unit of the present invention may specifically include:

[0055] During the off-peak period of the power grid load, the high-temperature steam generated by the coal-fired boiler 1 is transported to the reversible fuel cell 4, and the generator 3 supplies power to the reversible fuel cell 4, so that the reversible fuel cell 4 can electrolyze the high-temperature steam to produce hydrogen and oxygen in the electrolysis mode.

[0056] During the peak load period of the power grid, the hydrogen and oxygen generated by electrolysis of the reversible fuel cell 4 enter the reversible fuel cell 4. The reversible fuel cell reacts the hydrogen and oxygen to produce high-temperature steam and direct current in the power generation mode. The high-temperature steam generated enters the steam turbine 2 to generate work and the generated direct current is used to supply the power grid.

[0057] A reversible fuel cell-coupled coal-fired power unit peak-shaving method according to an embodiment of the present disclosure improves the efficiency of the coupled system, enhances the flexibility of the power grid, promotes the absorption of renewable energy, and reduces carbon emissions through bidirectional energy regulation of the reversible fuel cell and thermal integration optimization of the coal-fired power unit.

[0058] like Figure 1 As shown, the working process of a reversible fuel cell coupled coal-fired power generation unit peak regulation system of the present invention can be as follows:

[0059] Coal-fired boiler 1 generates steam, which drives turbine 2, which in turn drives generator 3 to generate electricity. This electricity is then supplied to the grid via load control center 7. Coal-fired boiler 1 extracts high-temperature flue gas to heat exchanger 5, which maintains the high temperature of reversible fuel cell 4, enabling it to maintain high efficiency at high temperatures.

[0060] During periods of low grid load, part of the steam generated by the coal-fired boiler 1 is extracted to the reversible fuel cell 4. In electrolysis mode (EC mode), the reversible fuel cell 4 uses the AC power generated by the generator 3 through the load control center 7, which is converted into DC power through the AC / DC inverter 6. The high-temperature steam is electrolyzed into water to produce hydrogen and oxygen. After passing through the gas separation device, the hydrogen and oxygen are stored in the hydrogen storage device 8 and the oxygen storage device 9, respectively.

[0061] During peak load periods of the power grid, hydrogen and oxygen stored in the hydrogen storage device 8 and the oxygen storage device 9 enter the reversible fuel cell 4. The reversible fuel cell 4 reacts the hydrogen and oxygen in the power generation mode (FC mode) to generate high-temperature steam and direct current (DC). The high-temperature steam can be used to generate power in the steam turbine 2. The DC is converted into AC through the AC / DC inverter 6. The AC power generated by the load control center 7 and the generator 3 is combined and supplied to the power grid.

[0062] The present invention is further described by coupling a 600MW coal-fired power unit with a 60MW R-SOFC peak-shaving system.

[0063] When a 600MW coal-fired power unit is not coupled with R-SOFC, the power generation load range is 50% to 100%, that is, 300 to 600MW load, and the load change rate is 1% / min, that is, 6MW / min.

[0064] 1) Coupled peak load shaving scenario:

[0065] During peak daytime photovoltaic generation, the coal-fired power units are reduced to a minimum of 50% load (300MW). The R-SOFC operates in SOEC mode, using extraction steam (2MPa, 300°C) for electrolysis to produce hydrogen. During this time, the R-SOFC consumes 60MW of power. Because extraction further reduces the turbine's work, the actual generator load can reach 45% (270MW), and the coupled peak-shaving system's actual output power drops to 35% (210MW).

[0066] During the evening peak electricity consumption, the R-SOFC switches to SOFC mode, consuming stored hydrogen to generate electricity, with the maximum power generation capacity reaching 60MW, increasing the output of the coal-fired power unit to 110% (660MW).

[0067] The peak-shaving range of coal-fired power units has been expanded to 35% to 110%, and the peak-shaving capacity has been improved.

[0068] 2) Coupled rapid load increase scenario:

[0069] When the grid load demands a rapid increase, the R-SOFC switches to power generation (FC) mode, consuming stored hydrogen to generate electricity. The load reaches its maximum power of 60 MW in 2 minutes. When the coupled system needs to rapidly increase its load by 120 MW, the R-SOFC takes 2 minutes to increase 60 MW, and the coal-fired unit takes 10 minutes to increase 60 MW. Both operations can be performed simultaneously, resulting in a total load increase of 120 MW in 10 minutes. Compared to the 20 minutes required for an uncoupled system to increase its load by 120 MW, the coupled system significantly shortens the load increase time.

[0070] 3) Coupled rapid load reduction scenario:

[0071] When the grid load command is rapidly reduced, the system generates 500MW of output power (440MW coal-fired power units + 60MW R-SOFC) in coupled mode before the load change. Upon receiving the load reduction command, the R-SOFC exits power generation (FC) mode, rapidly reducing the coupled system's output load to 440MW. The system then switches to electrolysis (EC) mode, further reducing the coupled system's output load to 380MW. The entire switching process takes 3-4 minutes to complete the 120MW load reduction command. Compared to the 20-minute load reduction required for an uncoupled system, the coupled system significantly shortens this time.

[0072] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A reversible fuel cell coupled coal-fired power unit peak shaving system, characterized in that: including coal-fired boilers, steam turbines, generators, and reversible fuel cells; The steam outlet of the coal-fired boiler is connected to the inlet of the reversible fuel cell, and the outlet of the reversible fuel cell is connected to the steam inlet of the steam turbine; wherein, During a low-load period of the power grid, the high-temperature steam generated by the coal-fired boiler is delivered to the reversible fuel cell, and the generator supplies power to the reversible fuel cell, so that the reversible fuel cell performs a water electrolysis reaction on the high-temperature steam in an electrolysis mode to produce hydrogen and oxygen; During peak load periods of the power grid, hydrogen and oxygen generated by electrolysis in the reversible fuel cell enter the reversible fuel cell, and the reversible fuel cell reacts the hydrogen and oxygen to produce high-temperature steam and direct current in the power generation mode. The high-temperature steam generated enters the steam turbine to generate power, and the generated direct current is used to supply the power grid.

2. The system according to claim 1, wherein: The system further includes a heat exchange device; The heat exchange device is arranged close to the reversible fuel cell; wherein, The inlet of the heat exchange device is connected to the flue gas outlet of the coal-fired boiler, and the outlet of the heat exchange device is connected to the flue gas inlet of the coal-fired boiler; The heat exchange device is used to receive the high-temperature flue gas from the coal-fired boiler to maintain the reversible fuel cell in a high-temperature state.

3. The system according to claim 1, wherein: The system also includes an AC / DC inverter; The AC / DC inverter is arranged between the reversible fuel cell and the generator, and is used for mutual conversion between direct current and alternating current.

4. The system according to claim 3, characterized in that The system also includes a load control center; The load control center is connected to the output end of the generator and the output end of the AC / DC inverter respectively, and is used to distribute electric energy to the power grid according to the load state of the power grid.

5. The system according to any one of claims 1 to 4, characterized in that The system also includes a gas separation device; The inlet of the gas separation device is connected to the outlet of the reversible fuel cell, and is used to separate hydrogen and oxygen generated by electrolysis of the reversible fuel cell.

6. The system according to claim 5, characterized in that The system also includes a hydrogen storage device; The inlet of the hydrogen storage device is connected to the first outlet of the gas separation device.

7. The system according to claim 5, characterized in that The system also includes an oxygen storage device; The inlet of the oxygen storage device is connected to the second outlet of the gas separation device.

8. The system according to any one of claims 1 to 4, characterized in that The reversible fuel cell is a reversible solid oxide fuel cell.

9. A reversible fuel cell coupled coal-fired power unit peak regulation method, characterized in that: A reversible fuel cell coupled coal-fired power generation unit peak shaving system according to any one of claims 1 to 8 is used; wherein the method comprises: During a low-load period of the power grid, the high-temperature steam generated by the coal-fired boiler is delivered to the reversible fuel cell, and the generator supplies power to the reversible fuel cell, so that the reversible fuel cell performs a water electrolysis reaction on the high-temperature steam in an electrolysis mode to produce hydrogen and oxygen; During peak load periods of the power grid, hydrogen and oxygen generated by electrolysis in the reversible fuel cell enter the reversible fuel cell, and the reversible fuel cell reacts the hydrogen and oxygen to produce high-temperature steam and direct current in the power generation mode. The high-temperature steam generated enters the steam turbine to generate power, and the generated direct current is used to supply the power grid.

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