A deep peak shaving coal-fired power generation system coupled with rsoc and a method for operating the same

Abstract

The application discloses a deep peak-regulation coal-fired power generation system coupled with RSOC and an operation method thereof, and the system comprises a coal-fired power generation unit thermal system, a reversible solid oxide fuel cell (RSOC) coupling system and a molten salt heat storage coupling system. When the power grid is in a low electricity consumption valley, the RSOC operates in an electric energy storage mode, the gas product is recycled into a boiler to stabilize combustion through reasonable design of the system configuration, the minimum technical output limit of the unit is broken, the peak-regulation capacity of the unit is increased, the bypass working medium, the waste heat of the reaction product and the molten salt heat storage are utilized to heat the feed water, the waste heat cascade utilization is realized, the SCR denitration efficiency under low load is improved, the clean and safe combustion on the boiler side and the efficient operation on the steam turbine side are realized in cooperation under the deep peak-regulation working condition, and the quick load change capacity of the unit is improved through flexible adjustment of the operation mode when the power grid is in a high electricity consumption peak. The application couples different power generation units, and widens the safe, efficient, flexible and clean operation domain of the coal-fired unit through material flow process reconstruction and energy ordered conversion.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired power technology, specifically relating to a deep peak-shaving coal-fired power generation system coupled with RSOC and its operation method. Background Technology

[0002] my country will continue to increase the installed capacity of renewable energy sources such as wind and solar power. However, due to their intermittent and uncertain characteristics, they pose significant challenges to the safe and stable operation of the power grid. my country's resource endowment, primarily based on coal, dictates that coal-fired power will continue to play a crucial role in ensuring my country's energy security and absorbing renewable energy for a considerable period. As the peak-to-valley difference on the power grid widens and electricity load changes become increasingly drastic and frequent, deep peak-shaving operation of coal-fired units has gradually become the norm. The peak-shaving capacity of coal-fired units is limited by their minimum technical output, resulting in poor operational stability and high energy consumption under low loads, which have become major concerns. Current research mainly focuses on exploring the stable combustion boundary of coal-fired units by tapping into their inherent potential, or increasing peak-shaving depth at the expense of unit economics. Coupled with different power generation units within a coal-fired power generation system, and rationally designed energy transfer and conversion methods, is one of the effective technical routes to improve the deep peak-shaving capacity of units.

[0003] Reversible solid oxide fuel cells (RSOCs) are clean, efficient, and flexible energy conversion devices with two different operating modes. These modes enable efficient storage and release of electrical energy. During RSOC operation, electrical energy and chemical energy are interconverted. The energy storage process requires high reaction temperatures, while the discharge process generates a large amount of high-temperature gaseous products. Therefore, by coupling a molten salt thermal storage system, energy flow transfer between the RSOC and the thermal system of the coal-fired unit can be achieved, comprehensively improving the unit's energy conversion efficiency. Summary of the Invention

[0004] To overcome the problems existing in the prior art, the present invention aims to provide a deep peak-shaving coal-fired power generation system coupled with RSOC and its operation method. By coupling a molten salt thermal storage system and a reversible solid oxide fuel cell (RSOC) system, the system configuration is rationally designed, the unit operation mode is adjusted, and the peak-shaving capacity of the unit is increased. It can achieve efficient storage of electricity during off-peak hours and rapid release of electricity during peak hours. It can also recover bypass working fluid, molten salt and waste heat from reaction products to heat boiler feedwater, improve the SCR denitrification efficiency of the boiler under extremely low load, and broaden the operating range of the coal-fired unit for safe, efficient, flexible and clean operation.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A deep peak-shaving coal-fired power generation system coupled with RSOC includes a coal-fired generator thermal system, a reversible solid oxide fuel cell RSOC coupling system, and a molten salt thermal storage coupling system;

[0007] The thermal system of the coal-fired power generation unit includes: a boiler 1, a high-pressure cylinder 2 of a steam turbine, an intermediate-pressure cylinder 3 of a steam turbine, a low-pressure cylinder 4 of a steam turbine, a generator 5, a condenser 6, a condensate pump 7, a heat storage medium feedwater heater 8, a low-pressure heater 9, a deaerator 10, a feedwater pump 11, a high-pressure heater 12, a first feedwater heater 13, a second feedwater heater 14, a bypass steam feedwater heater 15, and a bypass working medium pressure reducing valve 16. The superheated steam outlet of the boiler 1 is connected to the steam inlet of the high-pressure cylinder 2 of the steam turbine via a pipeline. The extraction steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the high-pressure heater 12 via a pipeline. The steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the intermediate-pressure cylinder 3 of the steam turbine via the boiler 1. The first-stage extraction steam outlet of the intermediate-pressure cylinder 3 is connected to the steam inlet of the high-pressure heater 12 via a pipeline. The second-stage extraction steam outlet is connected to the steam inlet of the deaerator 10 via a pipeline. The steam outlet of the intermediate-pressure cylinder 3 is connected to the steam turbine... The steam inlet of the low-pressure cylinder 4 is connected to the turbine via a pipeline. The extraction steam outlet of the low-pressure cylinder 4 is connected to the steam inlet of the low-pressure heater 9 via a pipeline. The steam outlet of the low-pressure cylinder 4 is connected to the condenser 6 via a pipeline. The condensate outlet of the condenser 6 is connected to the working fluid inlet of the heat storage medium feedwater heater 8 via a condensate pump 7. The working fluid outlet of the heat storage medium feedwater heater 8 is connected to the condensate inlet of the low-pressure heater 9. The condensate outlet of the low-pressure heater 9... The water outlet is connected to the feedwater inlet of the deaerator 10. The feedwater outlet of the deaerator 10 is connected to the feedwater inlet of the high-pressure heater 12 via the feedwater pump 11. The feedwater inlet of the boiler 1 is connected to the feedwater outlet of the high-pressure heater 12 via the first feedwater heater 13, the second feedwater heater 14, and the bypass steam feedwater heater 15. The high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 of the turbine are coaxial and connected to the power grid via the generator 5.

[0008] The reversible solid oxide fuel cell (RSOC) coupling system includes an RSOC stack 28, a first regenerator 30, a second regenerator 33, a third regenerator 29, a fourth regenerator 36, a first three-way mixing valve 31, a second three-way mixing valve 35, a first fan 34, a second fan 38, a first molten salt gas heat exchanger 22, a second molten salt gas heat exchanger 51, a fuel cell unit water pump 37, a first hydrogen storage tank 39, a second hydrogen storage tank 44, a water storage tank 43, a fuel cell unit condenser 40, a fuel cell unit gas-liquid separator 41, and a fuel cell unit dryer 42. The system includes: fuel cell unit feedwater regulating valve 45, electrolysis mode oxygen regulating valve 32, power generation mode oxygen regulating valve 50, boiler combustion stabilization valve 46, air exhaust valve 47, and piping connecting various devices; RSOC stack 28, first regenerator 30, second regenerator 33, third regenerator 29, fourth regenerator 36, first three-way mixing valve 31, second three-way mixing valve 35, first fan 34, second fan 38, first molten salt gas heat exchanger 22, fuel cell unit water pump 37, first hydrogen storage tank 39, second hydrogen storage tank 44, water storage tank 43, fuel cell... The fuel cell unit comprises a condenser 40, a steam-water separator 41, a dryer 42, a feedwater regulating valve 45, an oxygen regulating valve 32 for electrolysis mode, and an oxygen regulating valve 50 for power generation mode. The working fluid, water, originates from the outlet of the intermediate-pressure cylinder 3 of the steam turbine and is connected to the fuel cell unit via the feedwater regulating valve 45. It is then sequentially connected via pipelines through the fuel cell unit water pump 37 and the fuel side of the fourth regenerator 36. The reacted hydrogen passes through the first hydrogen storage tank 39, the first fan 34, the fuel side of the second regenerator 33, and the third regenerator 29. The fuel-side pipeline merges with the working fluid water at the second three-way mixing valve 35, and enters the fuel inlet of the RSOC stack 28 after passing through the fuel side of the first molten salt gas heat exchanger 22. The fuel outlet pipeline of the RSOC stack 28 passes sequentially through the tail gas side of the third regenerator 29, the fuel tail gas side of the second feedwater heater 14, the fuel cell unit condenser 40, the fuel cell unit steam-water separator 41, and the fuel cell unit dryer 42 before finally connecting to the second hydrogen storage tank 44 to form a closed fuel pipeline. The water separated by the fuel cell unit steam-water separator 41 enters the water storage tank 43 for storage.Outside air passes through the second fan 38, the first regenerator 30, the oxygen side of the first molten salt gas heat exchanger 22, and enters the oxygen inlet of the RSOC stack 28. The oxygen at the oxygen outlet of the RSOC stack 28 passes through the tail gas side of the first regenerator 30 and is divided into two paths at the first three-way mixing valve 31. One path passes through the electrolysis mode oxygen regulating valve 32, the tail gas side of the second regenerator 33, the tail gas side of the fourth regenerator 36, and the oxygen tail gas side of the first feedwater heater 13, and finally enters the coal-fired boiler through the boiler combustion stabilization valve 46 or is discharged to the outside environment through the air exhaust valve 47. The other path passes through the power generation mode oxygen regulating valve 50 and the oxygen side of the second molten salt gas heat exchanger 51 and is discharged to the outside environment.

[0009] The molten salt thermal storage coupling system includes a thermal storage medium cold tank 25, a thermal storage medium cold tank outlet regulating valve 26, a thermal storage medium cold tank outlet pump 27, a thermal storage medium bypass steam heater 18, a bypass steam regulating valve 17, a thermal storage medium first hot tank 19, a thermal storage medium first hot tank outlet regulating valve 20, a thermal storage medium first hot tank outlet pump 21, a thermal storage medium second hot tank 52, a thermal storage medium second hot tank outlet regulating valve 53, a thermal storage medium second hot tank outlet pump 54, a thermal storage medium power generation mode regulating valve 23, and a thermal storage medium three-way mixing valve 24. The thermal storage medium inlet of the thermal storage medium bypass steam heater 18 is connected to the thermal storage medium outlet of the thermal storage medium cold tank 25 through the thermal storage medium cold tank outlet pump 27 and the thermal storage medium cold tank outlet regulating valve 26. The thermal storage medium outlet of the thermal storage medium bypass steam heater 18 is connected to the thermal storage medium inlet of the thermal storage medium first hot tank 19 through a pipeline. The steam working medium inlet of the thermal storage medium bypass steam heater 18 is connected to the bypass steam regulating valve 17. The main steam outlet of boiler 1 is connected to the heat storage medium bypass steam heater 18, and the working fluid outlet of the heat storage medium bypass steam heater 18 is connected to the deaerator 10 through the bypass steam feedwater heater 15 and the bypass working fluid pressure reducing valve 16; the heat storage medium outlet of the first heat storage medium tank 19 is connected to the medium inlet of the first molten salt gas heat exchanger 22 through the heat storage medium first heat storage tank outlet pump 21 and the heat storage medium first heat storage tank outlet regulating valve 20; the medium outlet of the first molten salt gas heat exchanger 22 is connected to the heat storage medium in the heat storage medium cold tank 25. The inlet is connected to the thermal storage medium feedwater heater 8 via a three-way mixing valve 24; the thermal storage medium cold tank 25 is connected to the thermal storage medium second hot tank 52 via a thermal storage medium power generation mode regulating valve 23 and a second molten salt gas heat exchanger 51; the thermal storage medium outlet of the thermal storage medium second hot tank 52 is connected to the thermal storage medium inlet of the thermal storage medium feedwater heater 8 via a thermal storage medium second hot tank outlet regulating valve 53, a thermal storage medium second hot tank outlet pump 54 and a thermal storage medium three-way mixing valve 24.

[0010] The RSOC stack 28 is connected to the AC-to-DC inverter 48 and the DC-to-AC inverter 55 via cables. The AC-to-DC inverter 48 is connected to the power grid via the first switch 49, and the DC-to-AC inverter 55 is connected to the power grid via the second switch 56.

[0011] The operation method of the deep peak-shaving coal-fired power generation system coupled with RSOC is as follows:

[0012] (1) When there is a surplus of power in the power grid, the coal-fired power generating unit is in deep peak shaving operation mode, and the RSOC unit operates in electrolysis mode. When the first switch 49 is turned on, the power is converted into DC power by the AC to DC inverter 48 and then enters the RSOC unit for storage. The second fan 38 is turned on to flow air into the oxygen inlet of the RSOC stack 28. The oxygen regulating valve 50 in the power generation mode is closed and the oxygen regulating valve 32 in the electrolysis mode is opened. The oxygen-enriched air at the oxygen outlet preheats the reaction gas through the first regenerator 30, the second regenerator 33 and the fourth regenerator 36, and preheats the boiler feedwater through the first feedwater heater 13. The oxygen-enriched air after waste heat recovery is beneficial to the stable combustion of the boiler. Therefore, by adjusting the boiler combustion stabilization valve 46 and the air exhaust valve 47, the oxygen-enriched air after heat exchange is controlled to be transported through pipelines and finally enter the furnace to achieve stable combustion of the boiler under low load. The first blower 34 is turned on to draw hydrogen from the first hydrogen storage tank 39. At the same time, the fuel cell unit water supply regulating valve 45 and the fuel cell unit water pump 37 are turned on. By adjusting the speed of the fuel cell unit water pump, an appropriate amount of water is drawn from the outlet of the intermediate pressure cylinder 3 of the steam turbine and introduced into the fourth regenerator 36, where it is mixed with hydrogen at the second three-way mixing valve 35. Finally, the mixed gas flows into the RSOC stack 2. 8. Fuel Side: The hydrogen produced by electrolysis and the hydrogen input from the front end of the RSOC stack are reheated by the third regenerator 29 to reheat the unreacted gases, and the feedwater is preheated by the second feedwater heater 14. Finally, the hydrogen and water flow into the second hydrogen storage tank 44 and water storage tank 43 respectively through the fuel cell unit condenser 40, fuel cell unit steam-water separator 41, and fuel cell unit dryer 42 for storage. The bypass steam regulating valve 17 is opened to adjust the bypass steam flow rate, and the heat storage medium is heated in the heat storage medium bypass steam heater 18. The heat storage medium power generation mode regulating valve 23 and the heat storage medium are closed. The outlet regulating valve 53 of the second hot tank is opened, the outlet regulating valve 20 of the first hot tank of the heat storage medium is opened, the outlet pump 21 of the first hot tank of the heat storage medium is started, and the flow rate of the heat storage medium is adjusted. The heat storage medium flowing out of the first hot tank of the heat storage medium 19 flows through the first molten salt gas heat exchanger 22 to exchange heat with the working medium, creating the reaction conditions required for the electrolysis reaction. Then, the feed water is preheated through the heat storage medium feed water heater 8. At the same time, the steam extracted from the low-pressure cylinder is squeezed out to fill the working medium extracted due to the need for electrolysis of the RSOC unit, which increases the working medium flow rate of the low-pressure cylinder and improves the cylinder efficiency. The heat storage medium after waste heat utilization enters the cold tank of the heat storage medium 25.

[0013] (2) When the grid load increases rapidly, the RSOC unit operates in power generation mode, the second switch 56 is turned on, and the electrical energy generated by the RSOC stack 28 is converted into AC power by the DC-to-AC inverter 55 and then supplied to the grid. The first fan 34 draws out the hydrogen from the first hydrogen storage tank 39, which flows into the RSOC stack 28 through the second regenerator 33 and the third regenerator 29 respectively. The second fan 38 introduces oxygen, which enters the RSOC stack 28 after passing through the first regenerator 30. The two undergo an electrochemical reaction to supply power. The bypass steam regulating valve 17, the electrolysis mode oxygen regulating valve 32, and the power generation mode oxygen regulating valve 50 are adjusted to achieve the following: The purpose is as follows: During the rapid load increase of the coal-fired power generation unit, the flow rate of the main steam bypass is reduced and the flow rate of the working medium is increased. The high temperature generated by the chemical reaction is used to heat the heat storage medium through the second molten salt gas heat exchanger 51. The heated air is discharged into the atmosphere. The heat storage medium power generation mode regulating valve 23 and the heat storage medium second hot tank outlet regulating valve 53 are opened. The heat storage medium flows out from the heat storage medium cold tank 25, is heated by the second molten salt gas heat exchanger 51, and then flows through the heat storage medium second hot tank 52. The flow rate of the heat storage medium is regulated by the heat storage medium second hot tank outlet regulating valve 53 and the heat storage medium second hot tank outlet pump 54, and enters the heat storage medium feedwater heater 8 to heat the feedwater.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. This invention couples a molten salt thermal storage subsystem and a reversible solid oxide fuel cell (RSOC) subsystem, and rationally designs the system configuration. The molten salt thermal storage subsystem realizes the energy flow transfer between the coal-fired power generation thermal system and the RSOC system. The electrolysis process of RSOC realizes efficient storage of electrical energy, and the power generation process of RSOC realizes additional output of electrical energy. The operating mode can be flexibly adjusted according to the grid dispatch instructions, which improves the rapid load change capability of coal-fired units.

[0016] 2. This invention reconstructs the material flow path of a coal-fired unit under low-load operation, recovers gaseous products from the RSOC subsystem and introduces them into the boiler for stable combustion, effectively improving the boiler's operational stability under low load, breaking through the unit's minimum technical output limit, increasing the unit's peak-shaving capacity, and synergistically achieving clean and safe combustion on the boiler side and efficient operation on the turbine side under deep peak-shaving conditions.

[0017] 3. The present invention designs a closed-loop flow path for the working fluid inside the system, and uses the bypass working fluid, waste heat of reaction products and molten salt heat storage to heat the feedwater, thereby achieving comprehensive utilization of waste heat while increasing the flue gas temperature at the economizer outlet, improving the SCR denitrification efficiency under low load, and expanding the safe, efficient, clean and stable operation range of coal-fired units. Attached Figure Description

[0018] Figure 1This is a schematic diagram of a deep peak-shaving coal-fired power generation system coupled with RSOC. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, a deep peak-shaving coal-fired power generation system coupled with RSOC includes a coal-fired generator thermal system, a reversible solid oxide fuel cell RSOC coupling system, and a molten salt thermal storage coupling system.

[0021] The thermal system of the coal-fired power generation unit includes: boiler 1, high-pressure cylinder of steam turbine 2, intermediate-pressure cylinder of steam turbine 3, low-pressure cylinder of steam turbine 4, generator 5, condenser 6, condensate pump 7, heat storage medium feedwater heater 8, low-pressure heater 9, deaerator 10, feedwater pump 11, high-pressure heater 12, first feedwater heater 13, second feedwater heater 14, bypass steam feedwater heater 15, and bypass working medium pressure reducing valve 16; the superheated steam outlet of boiler 1 is connected to the steam inlet of high-pressure cylinder 2 of steam turbine via a pipeline; the extraction steam outlet of high-pressure cylinder 2 is connected to the steam inlet of high-pressure heater 12 via a pipeline; the steam outlet of high-pressure cylinder 2 is connected to the steam inlet of intermediate-pressure cylinder 3 of steam turbine via boiler 1; the first-stage extraction steam outlet of intermediate-pressure cylinder 3 is connected to the steam inlet of high-pressure heater 12 via a pipeline; the second-stage extraction steam outlet is connected to the steam inlet of deaerator 10 via a pipeline; and the steam outlet of intermediate-pressure cylinder 3 is connected to the steam inlet of the generator. The steam inlet of the low-pressure cylinder 4 is connected to the turbine through a pipeline. The extraction steam outlet of the turbine's low-pressure cylinder 4 is connected to the steam inlet of the low-pressure heater 9 through a pipeline. The steam outlet of the turbine's low-pressure cylinder 4 is connected to the condenser 6 through a pipeline. The condensate outlet of the condenser 6 is connected to the working fluid inlet of the thermal storage medium feedwater heater 8 through a condensate pump 7. The working fluid outlet of the thermal storage medium feedwater heater 8 is connected to the condensate inlet of the low-pressure heater 9. The condensate outlet of the low-pressure heater 9 is connected to the feedwater inlet of the deaerator 10. The feedwater outlet of the deaerator 10 is connected to the feedwater inlet of the high-pressure heater 12 through a feedwater pump 11. The feedwater inlet of the boiler 1 and the feedwater outlet of the high-pressure heater 12 are connected through the first feedwater heater 13, the second feedwater heater 14, and the bypass steam feedwater heater 15. The turbine's high-pressure cylinder 2, intermediate-pressure cylinder 3, and low-pressure cylinder 4 are coaxial and connected to the power grid through a generator 5.

[0022] The reversible solid oxide fuel cell (RSOC) coupling system includes an RSOC stack 28, a first regenerator 30, a second regenerator 33, a third regenerator 29, a fourth regenerator 36, a first three-way mixing valve 31, a second three-way mixing valve 35, a first fan 34, a second fan 38, a first molten salt gas heat exchanger 22, a second molten salt gas heat exchanger 51, a fuel cell unit water pump 37, a first hydrogen storage tank 39, a second hydrogen storage tank 44, a water storage tank 43, a fuel cell unit condenser 40, a fuel cell unit gas-liquid separator 41, a fuel cell unit dryer 42, and a fuel cell unit fuel cell unit dryer. The system includes a fuel cell unit water supply regulating valve 45, an electrolysis mode oxygen regulating valve 32, a power generation mode oxygen regulating valve 50, a boiler combustion stabilization valve 46, an air exhaust valve 47, and piping connecting various devices; the RSOC stack 28, a first regenerator 30, a second regenerator 33, a third regenerator 29, a fourth regenerator 36, a first three-way mixing valve 31, a second three-way mixing valve 35, a first fan 34, a second fan 38, a first molten salt gas heat exchanger 22, a fuel cell unit water pump 37, a first hydrogen storage tank 39, a second hydrogen storage tank 44, a water storage tank 43, and a fuel cell. The fuel cell unit comprises a unit condenser 40, a fuel cell unit steam-water separator 41, a fuel cell unit dryer 42, a fuel cell unit feedwater regulating valve 45, an electrolysis mode oxygen regulating valve 32, and a power generation mode oxygen regulating valve 50. The working fluid for electrolysis, water, originates from the outlet of the intermediate-pressure cylinder 3 of the steam turbine and is connected to the fuel cell unit via the fuel cell unit feedwater regulating valve 45. It is then sequentially connected via pipelines through the fuel cell unit water pump 37 and the fuel side of the fourth regenerator 36. The reacting hydrogen is transported via the first hydrogen storage tank 39, the first fan 34, the fuel side of the second regenerator 33, and the fuel side of the third regenerator 29. The pipeline connected to the feed side merges with the working fluid water at the second three-way mixing valve 35, and enters the fuel inlet end of the RSOC stack 28 after passing through the fuel side of the first molten salt gas heat exchanger 22. The fuel outlet pipeline of the RSOC stack 28 passes through the tail gas side of the third regenerator 29, the fuel tail gas side of the second feedwater heater 14, the fuel cell unit condenser 40, the fuel cell unit steam-water separator 41, and the fuel cell unit dryer 42 in sequence, and finally connects to the second hydrogen storage tank 44 to form a closed fuel pipeline. The water separated by the fuel cell unit steam-water separator 41 enters the water storage tank 43 for storage.Outside air passes through the second fan 38, the first regenerator 30, the oxygen side of the first molten salt gas heat exchanger 22, and enters the oxygen inlet of the RSOC stack 28. The oxygen at the RSOC stack 28's oxygen outlet passes through the tail gas side of the first regenerator 30 and is split into two paths at the first three-way mixing valve 31. One path passes through the electrolysis mode oxygen regulating valve 32, the tail gas side of the second regenerator 33, the tail gas side of the fourth regenerator 36, and the oxygen tail gas side of the first feedwater heater 13, finally entering the coal-fired boiler via the boiler combustion stabilization valve 46 or being discharged to the outside environment via the air exhaust valve 47. The other path passes through the power generation mode oxygen regulating valve 50 and the oxygen side of the second molten salt gas heat exchanger 51 before being discharged to the outside environment. The RSOC stack 28 is connected to the AC-to-DC inverter 48 and the DC-to-AC inverter 55 via cables. The AC-to-DC inverter 48 is connected to the power grid via the first switch 49, and the DC-to-AC inverter 55 is connected to the power grid via the second switch 56.

[0023] The molten salt thermal storage coupling system includes a thermal storage medium cold tank 25, a thermal storage medium cold tank outlet regulating valve 26, a thermal storage medium cold tank outlet pump 27, a thermal storage medium bypass steam heater 18, a bypass steam regulating valve 17, a thermal storage medium first hot tank 19, a thermal storage medium first hot tank outlet regulating valve 20, a thermal storage medium first hot tank outlet pump 21, a thermal storage medium second hot tank 52, a thermal storage medium second hot tank outlet regulating valve 53, a thermal storage medium second hot tank outlet pump 54, a thermal storage medium power generation mode regulating valve 23, and a thermal storage medium three-way mixing valve 24. The thermal storage medium inlet of the thermal storage medium bypass steam heater 18 is connected to the thermal storage medium outlet of the thermal storage medium cold tank 25 through the thermal storage medium cold tank outlet pump 27 and the thermal storage medium cold tank outlet regulating valve 26. The thermal storage medium outlet of the thermal storage medium bypass steam heater 18 is connected to the thermal storage medium inlet of the thermal storage medium first hot tank 19 through a pipeline. The steam working medium inlet of the thermal storage medium bypass steam heater 18 is connected to the boiler through the bypass steam regulating valve 17. The main steam outlet is connected to the heat storage medium bypass steam heater 18, and the working medium outlet of the heat storage medium bypass steam heater 18 is connected to the deaerator 10 through the bypass steam feedwater heater 15 and the bypass working medium pressure reducing valve 16; the heat storage medium outlet of the first heat storage medium tank 19 is connected to the medium inlet of the first molten salt gas heat exchanger 22 through the heat storage medium first heat storage tank outlet pump 21 and the heat storage medium first heat storage tank outlet regulating valve 20; the medium outlet of the first molten salt gas heat exchanger 22 is connected to the heat storage medium inlet of the heat storage medium cold tank 25 through the heat storage medium three-way mixing valve 24 and the heat storage medium feedwater heater 8; the heat storage medium cold tank 25 is connected to the heat storage medium second heat storage tank 52 through the heat storage medium power generation mode regulating valve 23 and the second molten salt gas heat exchanger 51; the heat storage medium outlet of the second heat storage tank 52 is connected to the heat storage medium inlet of the heat storage medium feedwater heater 8 through the heat storage medium second heat storage tank outlet regulating valve 53, the heat storage medium second heat storage tank outlet pump 54 and the heat storage medium three-way mixing valve 24.

[0024] As a clean, efficient, and flexible energy conversion device, the RSOC has two different operating modes, which enable efficient storage and release of electrical energy. During RSOC operation, electrical energy and chemical energy are interconverted. The energy storage process requires a high reaction temperature, and the discharge process generates a large amount of high-temperature gaseous products. Therefore, by coupling a molten salt thermal storage system, energy flow transfer between the RSOC and the thermal system of the coal-fired unit can be realized, thereby comprehensively improving the energy conversion efficiency of the unit.

[0025] When there is a surplus of electricity in the power grid, the coal-fired power generating unit operates in deep peak shaving mode, and the RSOC unit operates in electrolysis mode. The first switch 49 is opened, and electrical energy is converted to DC power via the AC-to-DC inverter 48 before entering the RSOC unit for storage. The second fan 38 is opened to draw air into the oxygen inlet of the RSOC stack 28. The oxygen regulating valve 50 for power generation mode is closed, and the oxygen regulating valve 32 for electrolysis mode is opened. Oxygen-enriched air at the oxygen outlet preheats the reaction gas through the first regenerator 30, the second regenerator 33, and the fourth regenerator 36, and preheats the boiler feedwater through the first feedwater heater 13. The first fan 34 draws hydrogen from the first hydrogen storage tank 39, and simultaneously the fuel cell unit feedwater regulating valve 45 and the fuel cell unit water pump 37 are opened. By adjusting the speed of the fuel cell unit water pump, an appropriate amount of water is drawn from the outlet of the intermediate-pressure cylinder 3 of the turbine and introduced into the fourth regenerator 36, where it mixes with hydrogen at the second three-way mixing valve 35. Finally, the mixed gas flows into... On the fuel side of the RSOC stack 28, hydrogen generated by electrolysis and hydrogen input from the front end of the RSOC stack are reheated by the third regenerator 29 to reheat unreacted gases, and the feedwater is preheated by the second feedwater heater 14. Finally, hydrogen and water flow into the second hydrogen storage tank 44 and water storage tank 43 respectively through the fuel cell unit condenser 40, fuel cell unit steam-water separator 41, and fuel cell unit dryer 42 for storage. In addition, when the coal-fired power generation unit is in deep peak shaving operation, problems such as boiler burner instability and flameout, uneven furnace heat load causing water-cooled wall tube rupture are prone to occur, which seriously threaten the safe and stable operation of the unit. Therefore, oxygen-enriched air after waste heat recovery is continued to be used. The boiler combustion stabilization valve 46 and air exhaust valve 47 are adjusted to control the oxygen-enriched air after heat exchange to be transported through pipelines and finally enter the furnace to achieve stable combustion of the boiler under low load. The air exhaust valve 47 is set to avoid water-cooled wall vaporization or hydrodynamic safety problems caused by excessive furnace heat exchange.

[0026] Open the bypass steam regulating valve 17, adjust the bypass steam flow rate, heat the thermal storage medium in the bypass steam heater 18, close the thermal storage medium power generation mode regulating valve 23 and the thermal storage medium second hot tank outlet regulating valve 53, open the thermal storage medium first hot tank outlet regulating valve 20, start the thermal storage medium first hot tank outlet pump 21, adjust the thermal storage medium flow rate, the thermal storage medium flowing out of the thermal storage medium first hot tank 19 flows through the first molten salt gas heat exchanger 22 to exchange heat with the reaction working medium, creating the reaction conditions required for the electrolysis reaction, and then preheat the feed water through the thermal storage medium feed water heater 8, while displacing the low-pressure cylinder extraction steam to fill the working medium extracted due to the need for RSOC unit electrolysis, increasing the working medium flow rate of the low-pressure cylinder and improving the low-pressure cylinder efficiency, the thermal storage medium after waste heat utilization enters the thermal storage medium cold tank 25;

[0027] When the grid load increases rapidly, taking the actual operating data of a 600MW single-reheat coal-fired power generating unit as an example, due to the large delay and inertia of the boiler subsystem, the unit's output cannot respond quickly. When the unit receives a load increase command of 1% of rated load per minute from the grid, the response time is on the order of ten seconds, and a power deviation of 3-5MW occurs in the initial stage of load increase. As the load increase rate increases, the response time and the power deviation in the initial stage of load change will also increase, affecting the unit's operation. Coupled with the RSOC system and set it to power generation mode, the unit's ability to quickly change load can be improved, and the unit's tracking performance of load commands can be improved. When the RSOC unit operates in power generation mode, the second switch 56 is turned on. The electrical energy generated by the RSOC stack 28 is converted into AC power by the DC-to-AC inverter 55 and then supplied to the grid. The first fan 34 draws out the hydrogen from the first hydrogen storage tank 39, which flows into the RSOC stack 28 through the second regenerator 33 and the third regenerator 29 respectively. The second fan 38 introduces oxygen, which enters the RSOC stack 28 after passing through the first regenerator 30. The two undergo an electrochemical reaction to supply power. The bypass steam regulating valve 17, the electrolysis mode oxygen regulating valve 32, and the power generation mode oxygen regulating valve 50 are adjusted. The purpose of the adjustment is to ensure that the oxygen supply in the coal-fired power generation mode is within the range of 24 hours. During the rapid load increase of the generator set, the main steam bypass flow is reduced and the working fluid flow is increased. The high temperature generated by the chemical reaction is used to heat the heat storage medium through the second molten salt gas heat exchanger 51. The heated air is discharged into the atmosphere. The heat storage medium power generation mode regulating valve 23 and the heat storage medium second hot tank outlet regulating valve 53 are opened. The heat storage medium flows out from the heat storage medium cold tank 25, is heated by the second molten salt gas heat exchanger 51, and then flows through the heat storage medium second hot tank 52. The heat storage medium flow rate is regulated by the heat storage medium second hot tank outlet regulating valve 53 and the heat storage medium second hot tank outlet pump 54, and enters the heat storage medium feedwater heater 8 to heat the feedwater.

[0028] During periods of low grid electricity demand, the RSOC operates in energy storage mode. Through a rationally designed system configuration, it recovers gaseous byproducts for stable boiler combustion, overcoming the minimum technical output limit of the unit and increasing its peak-shaving capacity. It also utilizes bypass working fluid, waste heat from reaction products, and molten salt heat storage to heat feedwater, achieving cascaded utilization of waste heat while improving SCR denitrification efficiency under low load. This synergistically achieves clean and safe combustion on the boiler side and efficient operation on the turbine side under deep peak-shaving conditions. During periods of high grid electricity demand, the RSOC operates in power generation mode, enhancing the unit's rapid load-changing capability through flexible adjustments to its operating mode. This invention couples different power generation units, expanding the safe, efficient, flexible, and clean operation domain of coal-fired units through material flow reconfiguration and orderly energy conversion.

Claims

1. A deep peak-shaving coal-fired power generation system coupled with RSOC, characterized in that: This includes the thermal system of a coal-fired power generation unit, the reversible solid oxide fuel cell (RSOC) coupling system, and the molten salt thermal storage coupling system; The thermal system of the coal-fired generator set includes: a boiler (1), a high-pressure cylinder of a steam turbine (2), a medium-pressure cylinder of a steam turbine (3), a low-pressure cylinder of a steam turbine (4), a generator (5), a condenser (6), a condensate pump (7), a heat storage medium feedwater heater (8), a low-pressure heater (9), a deaerator (10), a feedwater pump (11), a high-pressure heater (12), a first feedwater heater (13), a second feedwater heater (14), a bypass steam feedwater heater (15), and a bypass working fluid pressure reducing valve (16); the superheated steam of the boiler (1) The steam outlet of the high-pressure cylinder (2) of the steam turbine is connected to the steam inlet of the high-pressure heater (12) via a pipeline. The steam outlet of the high-pressure cylinder (2) of the steam turbine is connected to the steam inlet of the intermediate-pressure cylinder (3) of the steam turbine via the boiler (1). The first-stage extraction steam outlet of the intermediate-pressure cylinder (3) of the steam turbine is connected to the steam inlet of the high-pressure heater (12) via a pipeline. The second-stage extraction steam outlet is connected to the steam inlet of the deaerator (10) via a pipeline. The steam outlet of the intermediate-pressure cylinder (3) of the steam turbine... The steam inlet of the low-pressure cylinder (4) of the steam turbine is connected to the steam inlet of the low-pressure heater (9) via a pipeline. The steam outlet of the low-pressure cylinder (4) of the steam turbine is connected to the steam inlet of the low-pressure heater (9) via a pipeline. The steam outlet of the low-pressure cylinder (4) of the steam turbine is connected to the condenser (6) via a pipeline. The condensate outlet of the condenser (6) is connected to the working fluid inlet of the heat storage medium feedwater heater (8) via a condensate pump (7). The working fluid outlet of the heat storage medium feedwater heater (8) is connected to the condensate inlet of the low-pressure heater (9). The condensate outlet of the low-pressure heater (9) is connected to the steam inlet of the condenser (9). The water outlet is connected to the feedwater inlet of the deaerator (10), and the feedwater outlet of the deaerator (10) is connected to the feedwater inlet of the high-pressure heater (12) through the feedwater pump (11). The feedwater inlet of the boiler (1) is connected to the feedwater outlet of the high-pressure heater (12) through the first feedwater heater (13), the second feedwater heater (14) and the bypass steam feedwater heater (15). The high-pressure cylinder (2), the intermediate-pressure cylinder (3) and the low-pressure cylinder (4) of the steam turbine are coaxial and connected to the power grid through the generator (5). The reversible solid oxide fuel cell (RSOC) coupling system includes an RSOC stack (28), a first regenerator (30), a second regenerator (33), a third regenerator (29), a fourth regenerator (36), a first three-way mixing valve (31), a second three-way mixing valve (35), a first fan (34), a second fan (38), a first molten salt gas heat exchanger (22), a second molten salt gas heat exchanger (51), a fuel cell unit water pump (37), a first hydrogen storage tank (39), a second hydrogen storage tank (44), a water storage tank (43), a fuel cell unit condenser (40), a fuel cell unit gas-water separator (41), and a fuel cell unit dryer. (42) Fuel cell unit water supply regulating valve (45), electrolysis mode oxygen regulating valve (32), power generation mode oxygen regulating valve (50), boiler combustion stabilization valve (46), air exhaust valve (47), and pipelines connecting various equipment; wherein, RSOC stack (28), first regenerator (30), second regenerator (33), third regenerator (29), fourth regenerator (36), first three-way mixing valve (31), second three-way mixing valve (35), first fan (34), second fan (38), first molten salt gas heat exchanger (22), fuel cell unit water pump (37), first hydrogen storage tank (39), and second hydrogen storage tank (44). The fuel cell unit consists of a water storage tank (43), a fuel cell unit condenser (40), a fuel cell unit steam-water separator (41), a fuel cell unit dryer (42), a fuel cell unit feedwater regulating valve (45), an electrolysis mode oxygen regulating valve (32), and a power generation mode oxygen regulating valve (50). The working fluid water for electrolysis comes from the outlet of the intermediate pressure cylinder (3) of the steam turbine and is connected to the fuel cell unit by the fuel cell unit feedwater regulating valve (45). It is connected sequentially through pipelines via the fuel cell unit water pump (37) and the fuel side of the fourth regenerator (36). The reacting hydrogen passes through the first hydrogen storage tank (39), the first fan (34), the fuel side of the second regenerator (33), and the third... The pipeline connected to the fuel side of the regenerator (29) merges with the working fluid water at the second three-way mixing valve (35), and enters the fuel inlet end of the RSOC stack (28) after passing through the fuel side of the first molten salt gas heat exchanger (22). The fuel outlet pipeline of the RSOC stack (28) passes through the tail gas side of the third regenerator (29), the fuel tail gas side of the second feedwater heater (14), the fuel cell unit condenser (40), the fuel cell unit steam-water separator (41), and the fuel cell unit dryer (42) in sequence, and finally connects to the second hydrogen storage tank (44) to form a closed fuel pipeline. The water separated by the fuel cell unit steam-water separator (41) enters the water storage tank (43) for storage.Outside air passes through the second fan (38), the first regenerator (30), the oxygen side of the first molten salt gas heat exchanger (22), and enters the oxygen inlet of the RSOC stack (28). The oxygen at the oxygen outlet of the RSOC stack (28) passes through the tail gas side of the first regenerator (30) and is divided into two paths at the first three-way mixing valve (31). One path passes through the electrolysis mode oxygen regulating valve (32), the tail gas side of the second regenerator (33), the tail gas side of the fourth regenerator (36), and the oxygen tail gas side of the first feedwater heater (13), and finally enters the coal-fired boiler through the boiler combustion stabilization valve (46) or is discharged to the outside environment through the air exhaust valve (47). The other path passes through the power generation mode oxygen regulating valve (50) and the oxygen side of the second molten salt gas heat exchanger (51) and is discharged to the outside environment. The molten salt thermal storage coupling system includes a thermal storage medium cold tank (25), a thermal storage medium cold tank outlet regulating valve (26), a thermal storage medium cold tank outlet pump (27), a thermal storage medium bypass steam heater (18), a bypass steam regulating valve (17), a thermal storage medium first hot tank (19), a thermal storage medium first hot tank outlet regulating valve (20), a thermal storage medium first hot tank outlet pump (21), a thermal storage medium second hot tank (52), a thermal storage medium second hot tank outlet regulating valve (53), a thermal storage medium second hot tank outlet pump (54), and a thermal storage medium power generation system. The mode regulating valve (23) and the heat storage medium three-way mixing valve (24) are used. The heat storage medium inlet of the heat storage medium bypass steam heater (18) is connected to the heat storage medium outlet of the heat storage medium cold tank (25) through the heat storage medium cold tank outlet pump (27) and the heat storage medium cold tank outlet regulating valve (26). The heat storage medium outlet of the heat storage medium bypass steam heater (18) is connected to the heat storage medium inlet of the first heat storage medium tank (19) through a pipeline. The steam working medium inlet of the heat storage medium bypass steam heater (18) is connected to the boiler through the bypass steam regulating valve (17). The furnace (1) is connected to the main steam outlet. The working fluid outlet of the bypass steam heater (18) for the heat storage medium is connected to the deaerator (10) through the bypass steam feedwater heater (15) and the bypass working fluid pressure reducing valve (16). The heat storage medium outlet of the first hot tank (19) for the heat storage medium is connected to the medium inlet of the first molten salt gas heat exchanger (22) through the outlet pump (21) and the outlet regulating valve (20) of the first hot tank for the heat storage medium. The medium outlet of the first molten salt gas heat exchanger (22) is connected to the heat storage medium inlet of the cold tank (25) for the heat storage medium. The outlet is connected to the heat storage medium feedwater heater (8) via a three-way mixing valve (24); the heat storage medium cold tank (25) and the heat storage medium second hot tank (52) are connected via a heat storage medium power generation mode regulating valve (23) and the second molten salt gas heat exchanger (51); the heat storage medium outlet of the heat storage medium second hot tank (52) and the heat storage medium inlet of the heat storage medium feedwater heater (8) are connected via a heat storage medium second hot tank outlet regulating valve (53), a heat storage medium second hot tank outlet pump (54) and a heat storage medium three-way mixing valve (24); The RSOC stack (28) is connected to the AC-to-DC inverter (48) and the DC-to-AC inverter (55) via cables. The AC-to-DC inverter (48) is connected to the power grid via a first switch (49), and the DC-to-AC inverter (55) is connected to the power grid via a second switch (56).

2. The operation method of the deep peak-shaving coal-fired power generation system coupled with RSOC as described in claim 1, characterized in that, Specifically as follows: (1) When there is a surplus of power in the power grid, the coal-fired power generation unit is in deep peak shaving operation mode, the RSOC unit operates in electrolysis mode, the first switch (49) is turned on, the power is converted into DC power through the AC to DC inverter (48) and then enters the RSOC unit for storage, the second fan (38) is turned on to flow air into the RSOC stack (28). Oxygen inlet: Close the oxygen regulating valve (50) for power generation mode and open the oxygen regulating valve (32) for electrolysis mode. Oxygen-enriched air at the oxygen outlet preheats the reaction gas through the first regenerator (30), the second regenerator (33), and the fourth regenerator (36), and preheats the boiler feedwater through the first feedwater heater (13). The oxygen-enriched air after waste heat recovery is beneficial to the stable combustion of the boiler. Therefore, adjust the boiler combustion stabilization valve (46) and the air exhaust valve (47) to control the oxygen-enriched air after heat exchange to be transported through the pipeline and finally enter the furnace to achieve stable combustion of the boiler under low load. Open the first fan (34) to draw hydrogen from the first hydrogen storage tank (39), and at the same time open the fuel cell unit feedwater regulating valve (45) and the fuel cell unit water supply regulating valve. Pump (37) takes an appropriate amount of water from the outlet of the intermediate pressure cylinder (3) of the steam turbine and introduces it into the fourth regenerator (36) by adjusting the speed of the water pump of the fuel cell unit. Then it mixes with hydrogen in the second three-way mixing valve (35). Finally, the mixed gas flows into the fuel side of the RSOC stack (28). The hydrogen generated by electrolysis and the hydrogen input at the front end of the RSOC stack are reheated by the third regenerator (29) for the unreacted gas, and the feed water is preheated by the second feed water heater (14). Finally, the hydrogen and water flow into the second hydrogen storage tank (44) and the water storage tank (43) respectively through the fuel cell unit condenser (40), fuel cell unit steam-water separator (41), and fuel cell unit dryer (42) for storage. Open the bypass steam regulating valve (17), adjust the bypass steam flow rate, heat the thermal storage medium in the thermal storage medium bypass steam heater (18), close the thermal storage medium power generation mode regulating valve (23) and the thermal storage medium second hot tank outlet regulating valve (53), open the thermal storage medium first hot tank outlet regulating valve (20), start the thermal storage medium first hot tank outlet pump (21), adjust the thermal storage medium flow rate, the thermal storage medium flowing out from the thermal storage medium first hot tank (19) flows through the first molten salt gas heat exchanger (22) to exchange heat with the reaction working medium, creating the reaction conditions required for the electrolysis reaction, and then preheat the feed water through the thermal storage medium feed water heater (8), while squeezing out the low-pressure cylinder steam, filling the working medium extracted due to the need for RSOC unit electrolysis, increasing the working medium flow rate of the low-pressure cylinder, improving the low-pressure cylinder efficiency, and the thermal storage medium after waste heat utilization enters the thermal storage medium cold tank (25); (2) When the power grid load increases rapidly, the RSOC unit operates in power generation mode, and the second switch (56) is turned on. The electrical energy generated by the RSOC stack (28) is converted into AC power by the DC-to-AC inverter (55) and then supplied to the grid. The first fan (34) draws out the hydrogen from the first hydrogen storage tank (39) and flows into the RSOC stack (28) through the second regenerator (33) and the third regenerator (29). The second fan (38) introduces oxygen through the first regenerator (30) and then into the RSOC stack (28). The two undergo an electrochemical reaction to supply power. The bypass steam regulating valve (17), the electrolysis mode oxygen regulating valve (32), and the power generation mode oxygen regulating valve (50) are adjusted. The purpose of the adjustment is to reduce the main steam bypass flow rate and increase the flow rate of the working medium during the rapid load increase of the coal-fired power generation unit. The high temperature generated by the chemical reaction is used to heat the heat storage medium through the second molten salt gas heat exchanger (51). The heated air is discharged into the atmosphere. The heat storage medium power generation mode regulating valve (23) and the heat storage medium second hot tank outlet regulating valve (53) are opened. The heat storage medium flows out from the heat storage medium cold tank (25), is heated by the second molten salt gas heat exchanger (51), and flows through the heat storage medium second hot tank (52). The heat storage medium flow rate is regulated by the heat storage medium second hot tank outlet regulating valve (53) and the heat storage medium second hot tank outlet pump (54) and enters the heat storage medium feedwater heater (8) to heat the feedwater.

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