System and method for grid peak shaving of a biomass coupled coal-fired unit with molten salt thermal storage
By using molten salt thermal storage to assist biomass coupled with coal-fired power units, the problems of high carbon emissions and insufficient peak-shaving flexibility in traditional coal-fired power plants have been solved. This has enabled improved biomass gasification efficiency and rapid response to grid peak-shaving, resulting in significant environmental and economic benefits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHEAST UNIV
- Filing Date
- 2026-04-02
- Publication Date
- 2026-06-19
AI Technical Summary
Traditional coal-fired power plants have high carbon emissions and insufficient peak-shaving flexibility. Existing biomass-co-fired power generation technologies suffer from problems such as low gasification efficiency, high tar content, and slow load regulation. Molten salt thermal energy storage technology has not been deeply integrated with the biomass gasification process of coal-fired power plants.
A molten salt thermal storage system is adopted to assist biomass coupled with coal-fired power units. The molten salt energy storage system stores high-temperature flue gas thermal energy during the off-peak electricity consumption period and releases thermal energy during the peak period to assist the biomass gasification reaction. Combined with the control system, the output ratio of the molten salt and biomass gasification systems is dynamically allocated to form multiple peak-shaving response modes and optimize the peak-shaving response.
It significantly improves biomass gasification efficiency, enhances grid peak shaving flexibility and fuel utilization, reduces carbon emissions, and achieves rapid response and deep peak shaving, thus providing both environmental and economic benefits.
Smart Images
Figure CN122237014A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power generation technology, and in particular to a grid peak-shaving system and method for molten salt thermal storage-assisted biomass-coupled coal-fired power units. Background Technology
[0002] Traditional coal-fired power plants face two major challenges: high carbon emissions and insufficient peak-shaving flexibility. Existing biomass-co-fired power generation technologies, such as direct co-combustion and independent gasification followed by co-firing, suffer from low gasification efficiency, high tar content, significant impact on the main boiler, and slow load regulation. While molten salt thermal energy storage technology has been successfully applied in concentrated solar power (CSP), it has not yet been deeply integrated with the biomass gasification process in coal-fired power plants. Therefore, there is an urgent need for a molten salt thermal energy storage-assisted biogasification coupled coal-fired power plant system to simultaneously improve the low-carbon attributes and operational flexibility of the power plant. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this invention provides a grid peak-shaving system and method for molten salt thermal storage-assisted biomass-coupled coal-fired power units, aiming to solve the technical problems of slow response speed, low peak-shaving capacity, and high carbon emissions of existing coal-fired power units.
[0004] The technical solution adopted in this invention is as follows: This invention provides a grid peak-shaving system for molten salt thermal storage-assisted biomass-coupled coal-fired power units, comprising: Coal-fired power units include boilers and steam turbines; The biomass gasification system uses a biomass gasifier to produce gasified gas and stores it in a gas storage tank. The gasified gas is then supplied to the boiler furnace through the gas storage tank to assist in the combustion of pulverized coal. The molten salt energy storage system stores the heat energy of the high-temperature flue gas output from the boiler, after purification, and the exhaust gas output from the steam turbine, which enters the steam-molten salt heat exchanger during off-peak electricity demand periods. The heat energy stored in the molten salt is used to assist in driving the biomass gasification reaction. During peak electricity demand periods, the heat energy is released to heat the boiler feedwater, enabling the unit to rapidly increase its power generation capacity without increasing coal consumption. The control system is used to dynamically allocate the output ratio and action sequence of the molten salt energy storage system and the biomass gasification system according to the target peak-shaving power and its duration, forming multiple response modes to optimize the peak-shaving response; The molten salt energy storage system includes a molten salt main circuit formed by sequentially connecting the steam-molten salt heat exchanger, the high-temperature molten salt tank, the molten salt-feed water heat exchanger, and the low-temperature molten salt tank on the molten salt side. The gas-side inlet of the steam-molten salt heat exchanger is connected to the exhaust outlet of the steam turbine and the exhaust end of the clean flue gas; the high-temperature molten salt tank is connected to the heat exchange unit to form a molten salt output branch; the heat exchange unit uses high-temperature molten salt to preheat air and sends the preheated air to the air preheater; the air preheater uses the heat of the gasified gas output from the gasifier to preheat air, inputs the heat-absorbing high-temperature air into the gasifier, and sends the heat-releasing gasified gas to the gas storage tank. The molten salt-feedwater heat exchanger uses high-temperature molten salt to heat the boiler feedwater, and the heated feedwater enters the boiler.
[0005] The preferred technical solution is: The air outlet of the air preheater is connected to the gasifier inlet via a temperature detection heater, allowing the heat-absorbing high-temperature air to enter the gasifier to assist in driving the biomass gasification reaction.
[0006] The molten salt side outlet of the heat exchange unit is connected to the low-temperature molten salt tank to form a molten salt recovery branch, which together with the molten salt output branch constitutes a molten salt branch loop.
[0007] The control system includes a data processor, a controller, and a flow regulator. The data processor receives and processes power supply and demand data, transmits the processing results to the controller, and is signal-connected to the flow regulator. The feedback results of the flow regulator are then transmitted to the data processor to realize intelligent peak shaving of the power grid. The flow regulator includes several flow control units, which are used to control the flow rate of materials and working fluids within and between the molten salt energy storage system and the biomass gasification system.
[0008] The high-temperature flue gas outlet of the boiler is connected to a flue gas purification device, which is used to purify the high-temperature flue gas to obtain the clean flue gas. The clean flue gas outlet of the flue gas purification device is connected to the steam-molten salt heat exchanger.
[0009] The gas-side outlet of the steam-molten salt heat exchanger is connected to the chimney of the coal-fired unit to discharge the exhaust gas and clean flue gas after heat exchange.
[0010] The present invention also provides a peak-shaving method for a power grid peak-shaving system based on the molten salt thermal storage-assisted biomass coupled coal-fired power unit, comprising: S1. The control system receives grid dispatch instructions in real time and calculates the additional output required by the coal-fired unit, i.e., the target peak-shaving power ΔP. S2. The control system, based on a preset first power threshold P set1 With the second power threshold P set2 P set2 >P set1 and duration threshold T setAutomatically select one of the following three response modes: Molten salt standalone response mode: if ΔP ≤ P set1 If the load fluctuation is small, the control system instructs the molten salt energy storage system to increase the molten salt flow into the molten salt-feed water heat exchanger by adjusting the opening of the outlet valve of the high-temperature molten salt tank, so that the unit's power generation can respond to the grid demand, and instructs the biomass gasification system not to start. Collaborative mode: If P set1 <ΔP ≤ P set2 If the load is determined to be a peak-shaving load requiring continuous support, the control system instructs the molten salt energy storage system to increase its output to its maximum value P at the maximum ramp rate. max To quickly meet load demands, the biomass gasification system is simultaneously instructed to start and generate power. Gasification main mode: If ΔP>P set2 Or peak shaving duration t>T set If the system detects an extreme load or requires prolonged support, it instructs the valve that supplies high-temperature molten salt to the heat exchange unit to be reduced or shut off, causing the molten salt energy storage system to drop from its peak output to a lower power level that can be sustained. At the same time, it instructs the biomass gasification system to increase its output, generating more gasified gas to participate in combustion, taking on the main part of ΔP, and recovering the waste heat of its own process to maintain thermal balance. S3. If ΔP changes during peak shaving, repeat steps S1-S2 to achieve a smooth transition between mode switching and power output.
[0011] P set1 The value is set to 20% to 40% of the rated heating power of the molten salt-feedwater heat exchanger; P set2 The rated heating power of the molten salt-feed water heat exchanger is set to 70% to 90%.
[0012] T set Based on the theoretical sustainable heat release time of molten salt energy storage systems at maximum power... T MAX calculate: , where 0.5 ≤ k ≤ 0.8.
[0013] T MAX The calculations include: Among them, the total thermal energy stored in the molten salt energy storage system is Q = M × C p ×ΔT, M、 C p ΔT and ΔT are the total mass of molten salt, the average specific heat capacity of molten salt, and the design temperature difference between the low-temperature molten salt tank and the high-temperature molten salt tank, respectively. PMAX This is the rated heat release power of the molten salt energy storage system.
[0014] The technical solution of the present invention can achieve at least some of the following beneficial effects: This invention utilizes the high-temperature characteristics of molten salt to significantly improve biomass gasification efficiency and gasification gas quality. Through the rapid response characteristics of molten salt thermal storage, the biomass gasification-co-firing stage becomes a rapid peak-shaving unit for power plants. This enables the efficient and large-scale utilization of biomass energy, reducing the carbon emission intensity of coal-fired power plants. It not only improves fuel utilization but also significantly enhances the flexibility and efficiency of grid peak shaving, reduces operating and maintenance costs, and minimizes negative environmental impacts.
[0015] This invention deeply couples waste heat recovery from coal-fired power units, biomass gasification conversion, and power generation peak shaving through a molten salt thermal storage circuit. It uses low-grade waste heat, after being heated, as an external heat source for biomass gasification, achieving an upgraded energy storage from "low-grade thermal energy" to "high-grade gasification chemical energy." This significantly enhances the flexibility of deep peak shaving for coal-fired power units, realizing deep recovery of industrial waste heat and large-scale stable utilization of biomass energy, resulting in both outstanding environmental and economic benefits.
[0016] This invention proposes a hierarchical collaborative control strategy based on the target peak-shaving power ΔP and preset power and time thresholds. It automatically selects three working modes according to grid demand: "molten salt independent response mode", "collaborative mode" and "gasification gas main mode". It fully leverages the complementary advantages of the fast response speed of molten salt and the high energy density of gasification gas. Furthermore, it innovatively designs a "waste heat self-sustaining mode" for the gasifier. During deep peak shaving, it reduces external molten salt heating and instead recovers waste heat from gasification gas power generation to maintain the basic operation of the gasifier, thus achieving comprehensive optimization of peak shaving response speed, depth and duration.
[0017] This invention, a molten salt thermal storage-assisted biomass gasification coupled with a coal-fired power unit, not only achieves fuel flexibility for coal-fired units but also provides operational flexibility. On one hand, utilizing biomass can reduce carbon emissions. On the other hand, because the biomass gasifier and molten salt thermal storage system have strong rapid start-up, shutdown, and regulation capabilities, this technology can also improve the unit's load response capability.
[0018] Other features and advantages of the invention will be set forth in the following description or may be learned by practicing the invention. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention.
[0020] Explanation of reference numerals in the attached drawings: 1. Crusher; 2. Coal mill; 3. Gasifier; 4. Heat exchange unit; 5. Air preheater; 6. Gas storage tank; 7. First fan; 8. Second fan; 9. First burner; 10. Second burner; 11. Boiler; 12. Steam turbine; 13. Flue gas purification device; 14. Steam-molten salt heat exchanger; 15. Molten salt-feedwater heat exchanger; 16. Low-temperature molten salt tank; 17. High-temperature molten salt tank; 22. Sixth pipeline; 23. Fourth pipeline; 24. Third pipeline; 26. First pipeline; 31. Seventh pipeline; 33. First valve; 34. Second valve; 35. Third valve; 36. Fourth valve; 37. Fifth valve; 38. Sixth valve; 39. Seventh valve; 40. Eighth valve; 41. Ninth valve; 42. Tenth valve; 43. Temperature detection heater; 44. Fifth pipeline; 45. Second pipeline. Detailed Implementation
[0021] The specific embodiments of the present invention are described below with reference to the accompanying drawings.
[0022] Example 1
[0023] See Figure 1 This embodiment of a molten salt thermal storage-assisted biomass coupled coal-fired power unit grid peak shaving system includes a coal-fired power unit, a biomass gasification system, a molten salt energy storage system, and a control system. The coal-fired unit includes a boiler 11 and a steam turbine 12. Specifically, in the coal-fired unit, a coal mill 2 grinds raw coal into solid fuel and feeds pulverized coal through a pulverized coal pipe to a feed pipe. One end of the feed pipe is connected to a first blower 7. The primary air and pulverized coal are mixed and enter the furnace of the boiler 11 for combustion via a first burner 9. The high-temperature and high-pressure steam generated by the boiler 11 is input into the steam turbine 12, which drives the generator to perform work. A first valve 33 is installed on the pulverized coal pipe, and a fourth valve 36 is installed between the feed pipe and the first blower 7.
[0024] The biomass gasification system utilizes a biomass gasifier 3 to produce gasified gas, which is stored in a gas storage tank 6. The gasified gas is then supplied to the furnace of the boiler 11 through the gas storage tank 6 to assist in pulverized coal combustion. Specifically, in the biomass gasification system, the biomass feedstock is crushed by a crusher 1 and fed into the gasifier 3 via a conveying pipe, where it is converted into biomass gasified gas. A second valve 34 is installed on the conveying pipe. A third valve 35 is installed at the outlet of the gas storage tank 6, which is connected to the second burner 10 of the boiler 11 via a gas conveying pipe. A second blower 8 is also connected to the gas conveying pipe to supply secondary air mixed with the gasified gas to the furnace. A fifth valve 37 is installed at the outlet of the second blower 8.
[0025] The molten salt energy storage system comprises a molten salt main circuit formed by sequentially connecting a steam-molten salt heat exchanger 14, a high-temperature molten salt tank 17, a molten salt-feedwater heat exchanger 15, and a low-temperature molten salt tank 16 on the molten salt side. During off-peak electricity demand periods, the molten salt energy storage system stores the heat energy from the purified flue gas from the high-temperature flue gas output from the boiler 11 and the exhaust gas from the turbine 12, which then enters the steam-molten salt heat exchanger 14. The stored heat energy is used to assist in driving the biomass gasification reaction. During peak electricity demand periods, the system releases heat energy to heat the boiler feedwater. Compared to existing technologies that utilize turbine steam extraction, this method allows the unit to rapidly increase power generation without increasing coal consumption.
[0026] Among them, a seventh valve 39 is provided on the connecting pipeline between the molten salt outlet of the high-temperature molten salt tank 17 and the molten salt inlet of the molten salt-feed water heat exchanger 15, and a sixth valve 38 is provided on the connecting pipeline between the molten salt outlet of the low-temperature molten salt tank 16 and the molten salt inlet of the steam-molten salt heat exchanger 14.
[0027] The gas-side inlet of the steam-molten salt heat exchanger 14 is connected to the exhaust gas outlet of the steam turbine 12 via a first pipeline 26, and is also connected to the exhaust end of the clean flue gas; a tenth valve 42 is installed on the first pipeline 26.
[0028] In a specific manner, the high-temperature flue gas outlet of boiler 11 is connected to flue gas purification device 13, which purifies the high-temperature flue gas to obtain clean flue gas, and sends the clean flue gas to steam-molten salt heat exchanger 14 through a gas supply pipe; a ninth valve 41 is installed on the gas supply pipe.
[0029] In a specific manner, the gas-side outlet of the steam-molten salt heat exchanger 14 is connected to the chimney of the coal-fired unit through a second pipeline 45 to discharge the heat-exchanged exhaust gas and clean flue gas.
[0030] The high-temperature molten salt tank 17 is connected to the heat exchange unit 4 through the third pipeline 24 to form a molten salt output branch. The heat exchange unit 4 uses the high-temperature molten salt to preheat the air and sends the preheated air to the air preheater 5 through the fourth pipeline 23. An eighth valve 40 is installed on the third pipeline 24.
[0031] In a specific manner, the molten salt side outlet of the heat exchange unit 4 is connected to the low-temperature molten salt tank 16 through the fifth pipeline 44 to form a molten salt recovery branch, which together with the molten salt output branch constitutes a molten salt branch loop.
[0032] The high-temperature side inlet of the air preheater 5 is connected to the gas outlet of the gasifier 3. The heat of the gasified gas output from the gasifier 3 is used to preheat the air, and the high-temperature air after absorbing heat is sent back to the gasifier 3 through the sixth pipeline 22 to recover the waste heat of the gasified gas and provide driving force for the gasification reaction. The gasified gas after releasing heat is sent to the gas storage tank 6.
[0033] As a preferred embodiment, the air outlet of the air preheater 5 is connected to the gasifier inlet via a temperature detection heater 43, so that the high-temperature air after heat absorption is re-regulated by the temperature detection heater 43 to meet the requirements before entering the gasifier 3 to assist in driving the biomass gasification reaction.
[0034] The water-side inlet of the molten salt-feedwater heat exchanger 15 is connected to an external water source, and the water-side outlet is connected to the feedwater inlet of the boiler 11 via the seventh pipe 31, using high-temperature molten salt to heat the boiler feedwater. Specifically, during heat release, the high-temperature molten salt drawn from the high-temperature molten salt tank 17 enters the molten salt-feedwater heat exchanger 15 to release heat and heat the feedwater. The heated feedwater then enters the boiler, while the released low-temperature molten salt is transported to the low-temperature molten salt tank 16 for storage.
[0035] The control system dynamically allocates the output ratio and action sequence of the molten salt energy storage system and the biomass gasification system according to the target peak-shaving power and its duration, forming multiple response modes to optimize the peak-shaving response.
[0036] As a preferred embodiment, the control system includes a data processor, a controller, and a flow regulator. The data processor receives and processes power supply and demand data, transmits the processing results to the controller, and is signal-connected to the flow regulator. The feedback results of the flow regulator are then transmitted to the data processor to realize intelligent peak shaving of the power grid. The flow regulator includes several flow control units, which are used to control the flow rate of materials and working fluids within and between the molten salt energy storage system and the biomass gasification system.
[0037] Specifically, the plurality of flow control units include the sixth valve 38, the seventh valve 39, the eighth valve 40, the ninth valve 41, the tenth valve 42, and the first valve 33, the second valve 34, the third valve 35, the fourth valve 36, the fifth valve 37, the sixth valve 38, and the seventh valve 39.
[0038] Example 2 This embodiment provides a peak-shaving method for the power grid peak-shaving system of the molten salt thermal storage-assisted biomass coupled coal-fired unit described in Embodiment 1. The method is as follows: During off-peak electricity consumption periods, the high-temperature flue gas generated by the boiler and the exhaust steam from the turbine are transported to a steam-molten salt heat exchanger to store the waste heat in the molten salt energy storage system. The heat energy stored in the molten salt energy storage system is used as the main heat source to drive the biomass gasification reaction and input into the gasifier, thereby converting low-grade industrial waste heat into high-grade gasification chemical energy. A portion of the gasified gas produced by the gasifier is input into a coal-fired boiler for combustion assistance, while the excess gasified gas is stored in a gas storage tank. During peak electricity demand, the thermal energy stored in the molten salt energy storage system is used to heat the boiler feedwater through a molten salt-feedwater heat exchanger, enabling the unit to rapidly increase its power generation capacity without increasing coal consumption in response to peak grid loads. The gasified gas stored in the gas storage tank is then transported to the boiler for power generation, further supplementing the peak grid load. During this phase, the biomass gasification system switches to a low-load operation mode, relying mainly on the waste heat generated by recovering biomass gas and temperature detection heaters to maintain basic operation, thereby releasing all the high-grade thermal energy stored in the molten salt for peak power regulation.
[0039] Specifically, the peak-shaving method dynamically allocates the output power and action timing of the molten salt energy storage subsystem and the biomass gasification gas subsystem based on the target peak-shaving power magnitude and its duration. A preferred embodiment includes the following steps: S1. The control system receives grid dispatch instructions in real time and calculates the required increase in output of the coal-fired power unit, i.e., the target peak-shaving power ΔP. Here, ΔP is the difference between the real-time load instruction from the grid and the current output of the unit.
[0040] S2. The control system, based on a preset first power threshold P set1 With the second power threshold P set2 P set2 >P set1 and duration threshold T set Automatically select one of the following three response modes: Molten salt standalone response mode: if ΔP ≤ P set1 If the load fluctuation is small, the control system instructs the molten salt energy storage system to increase the flow of molten salt into the molten salt-feed water heat exchanger 15 by adjusting the opening of the outlet valve of the high-temperature molten salt tank 17, so that the unit's power generation responds to the grid demand, and instructs the biomass gasification system not to start, that is, the gasified gas does not participate in the boiler combustion. Collaborative mode: If P set1 <ΔP ≤ P set2 If the load is determined to be a peak-shaving load requiring continuous support, the control system instructs the molten salt energy storage system to increase its output to its maximum value P at the maximum ramp rate. max To quickly meet load demands, the biomass gasification system is instructed to start and output power, i.e., the gasified gas participates in boiler combustion. Gasification main mode: If ΔP>P set2 Or peak shaving duration t>T setIf the system determines that it needs to handle extremely high loads or support for a long time, the control system instructs the eighth valve 40 of the high-temperature molten salt tank 17 to reduce or cut off the output of high-temperature molten salt to the heat exchange unit 4, so that the molten salt energy storage system drops from its peak output to a lower power level that can be operated sustainably, in order to preserve its rapid response capability. At the same time, the system instructs the biomass gasification system to increase its output, generate more gasified gas to participate in combustion, undertake the main part of ΔP, and recover the waste heat of its own process to maintain thermal balance, that is, to cut off the molten salt heating as much as possible to reduce the heat exchange of the air preheater 5, so that the gasified gas discharged from the gasifier is directly returned to the gasifier 3 from the temperature detection heater 43.
[0041] S3. If ΔP changes during peak shaving, repeat steps S1-S2 to achieve a smooth transition between mode switching and power output.
[0042] Preferred, P set1 The rated heating power of the molten salt-feedwater heat exchanger 15 is set to 20% to 40%; P set2 The rated heating power of the molten salt-feed water heat exchanger 15 is set to 70% to 90%.
[0043] Preferred, T set Based on the theoretical sustainable heat release time of molten salt energy storage systems at maximum power... T MAX calculate: , where 0.5 ≤ k ≤ 0.8. The total thermal energy stored in the molten salt energy storage system is Q = M × C p ×ΔT, M、 C p ΔT and ΔT are the total mass of molten salt, the average specific heat capacity of molten salt, and the design temperature difference between the low-temperature molten salt tank and the high-temperature molten salt tank, respectively. P MAX This is the rated heat release power of the molten salt energy storage system.
[0044] In summary, this invention deeply couples waste heat recovery from coal-fired power units, biomass gasification conversion, and power generation peak shaving through a molten salt thermal storage circuit. By switching different system operation modes for different grid load periods, it significantly enhances the flexibility of deep peak shaving for coal-fired power units, realizes the cascade utilization of industrial waste heat and the large-scale stable conversion of biomass energy, and has good environmental and economic benefits.
[0045] It will be understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A grid peak-shaving system for molten salt thermal storage-assisted biomass-coupled coal-fired power units, characterized in that, include: Coal-fired power units include boilers and steam turbines; The biomass gasification system uses a biomass gasifier to produce gasified gas and stores it in a gas storage tank. The gasified gas is then supplied to the boiler furnace through the gas storage tank to assist in the combustion of pulverized coal. The molten salt energy storage system stores the heat energy of the high-temperature flue gas output from the boiler and the purified clean flue gas and exhaust gas output from the steam turbine during the off-peak electricity demand period. The heat energy stored in the molten salt is used to assist in driving the biomass gasification reaction. During the peak electricity demand period, the heat energy is released to heat the boiler feedwater, enabling the unit to quickly increase the power generation capacity without increasing coal consumption. The control system is used to dynamically allocate the output ratio and action sequence of the molten salt energy storage system and the biomass gasification system according to the target peak-shaving power and its duration, forming multiple response modes to optimize the peak-shaving response; The molten salt energy storage system includes a molten salt main circuit formed by sequentially connecting the steam-molten salt heat exchanger, the high-temperature molten salt tank, the molten salt-feed water heat exchanger, and the low-temperature molten salt tank on the molten salt side. The gas-side inlet of the steam-molten salt heat exchanger is connected to the exhaust outlet of the steam turbine and the exhaust end of the clean flue gas; the high-temperature molten salt tank is connected to the heat exchange unit to form a molten salt output branch; the heat exchange unit uses high-temperature molten salt to preheat air and sends the preheated air to the air preheater; the air preheater uses the heat of the gasified gas output from the gasifier to preheat air, inputs the heat-absorbing high-temperature air into the gasifier, and sends the heat-releasing gasified gas to the gas storage tank. The molten salt-feedwater heat exchanger uses high-temperature molten salt to heat the boiler feedwater, and the heated feedwater enters the boiler.
2. The grid peak-shaving system for molten salt thermal storage-assisted biomass-coupled coal-fired power units according to claim 1, characterized in that, The air outlet of the air preheater is connected to the gasifier inlet via a temperature detection heater, allowing the heat-absorbing high-temperature air to enter the gasifier to assist in driving the biomass gasification reaction.
3. The grid peak-shaving system for molten salt thermal storage-assisted biomass-coupled coal-fired power units according to claim 1, characterized in that, The molten salt side outlet of the heat exchange unit is connected to the low-temperature molten salt tank to form a molten salt recovery branch, which together with the molten salt output branch constitutes a molten salt branch loop.
4. The grid peak-shaving system for molten salt thermal storage-assisted biomass-coupled coal-fired power units according to claim 1, characterized in that, The control system includes a data processor, a controller, and a flow regulator. The data processor receives and processes power supply and demand data, transmits the processing results to the controller, and is signal-connected to the flow regulator. The feedback results of the flow regulator are then transmitted to the data processor to realize intelligent peak shaving of the power grid. The flow regulator includes several flow control units, which are used to control the flow rate of materials and working fluids within and between the molten salt energy storage system and the biomass gasification system.
5. The grid peak-shaving system for molten salt thermal storage-assisted biomass-coupled coal-fired power units according to claim 1, characterized in that, The high-temperature flue gas outlet of the boiler is connected to a flue gas purification device, which is used to purify the high-temperature flue gas to obtain the clean flue gas. The clean flue gas outlet of the flue gas purification device is connected to the steam-molten salt heat exchanger.
6. The grid peak-shaving system for molten salt thermal storage-assisted biomass-coupled coal-fired power units according to claim 1, characterized in that, The gas-side outlet of the steam-molten salt heat exchanger is connected to the chimney of the coal-fired unit to discharge the exhaust gas and clean flue gas after heat exchange.
7. A peak-shaving method for a power grid peak-shaving system for a molten salt thermal storage-assisted biomass-coupled coal-fired power unit according to any one of claims 1-6, characterized in that, include: S1. The control system receives grid dispatch instructions in real time and calculates the additional output required by the coal-fired unit, i.e., the target peak-shaving power ΔP. S2. The control system, based on a preset first power threshold P set1 With the second power threshold P set2 P set2 > P set1 and duration threshold T set Automatically select one of the following three response modes: Molten salt standalone response mode: if ΔP ≤ P set1 If the load fluctuation is small, the control system instructs the molten salt energy storage system to increase the molten salt flow into the molten salt-feed water heat exchanger by adjusting the opening of the outlet valve of the high-temperature molten salt tank, so that the unit's power generation can respond to the grid demand, and instructs the biomass gasification system not to start. Collaborative mode: If P set1 < ΔP ≤ P set2 If the load is determined to be a peak-shaving load requiring continuous support, the control system instructs the molten salt energy storage system to increase its output to its maximum value P at the maximum ramp rate. max To quickly meet load demands, the biomass gasification system is simultaneously instructed to start and generate power. Gasification main mode: If ΔP > P set2 Or peak shaving duration t > T set If the system detects an extreme load or requires prolonged support, it instructs the valve that supplies high-temperature molten salt to the heat exchange unit to be reduced or shut off, causing the molten salt energy storage system to drop from its peak output to a lower power level that can be sustained. At the same time, it instructs the biomass gasification system to increase its output, generating more gasified gas to participate in combustion, taking on the main part of ΔP, and recovering the waste heat of its own process to maintain thermal balance. S3. If ΔP changes during peak shaving, repeat steps S1-S2 to achieve a smooth transition between mode switching and power output.
8. The peak-shaving method according to claim 7, characterized in that, P set1 The value is set to 20% to 40% of the rated heating power of the molten salt-feedwater heat exchanger; P set2 The rated heating power of the molten salt-feed water heat exchanger is set to 70% to 90%.
9. The peak-shaving method according to claim 7, characterized in that, T set Based on the theoretical sustainable heat release time of molten salt energy storage systems at maximum power... T MAX calculate: , where 0.5 ≤ k ≤ 0.
8.
10. The peak-shaving method according to claim 9, characterized in that, T MAX The calculations include: The total thermal energy stored in the molten salt energy storage system is Q = M × C p ×ΔT, M、 C p ΔT and ΔT are the total mass of molten salt, the average specific heat capacity of molten salt, and the design temperature difference between the low-temperature molten salt tank and the high-temperature molten salt tank, respectively. P MAX This is the rated heat release power of the molten salt energy storage system.