Peak shaving system and method for coal and biomass blending combustion power grid

Abstract

The invention belongs to the technical field of power grid peak regulation, and discloses a coal and biomass blending combustion power grid peak regulation system and method. The power grid peak regulation system comprises a feeding device, a stock bin, a boiler, a feeding pipe, a first steam turbine, a flue gas purification device, a fused salt energy storage system and a compressed air energy storage system. According to the power grid peak regulation system, compressed air energy storage and fused salt energy storage technologies are combined, the efficient, economical and environment-friendly power grid peak regulation system is provided, and the power grid peak regulation system can store redundant electric energy and heat energy in the power utilization low peak period and release the energy in the power utilization peak period to meet the power utilization requirement; in addition, the power grid peak regulation system can recycle heat in flue gas waste heat and steam turbine exhaust gas, the power generation amount is increased, meanwhile, heat loss of the system is reduced, the energy utilization efficiency is improved, the power grid load is balanced, the pressure of the peak load on the power grid is reduced, and the operation efficiency and reliability of the power grid are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid peak regulation, and in particular to a power grid peak regulation system and method for mixed combustion of coal and biomass. Background Art

[0002] In traditional power systems, grid peak regulation is an important technical challenge. With the rapid development of renewable energy, grid load fluctuations have become more severe and unpredictable, which further increases the difficulty of grid peak regulation. Traditional peak regulation methods often rely on adjusting the amount of fossil fuels, which not only reduces combustion efficiency but also has low sensitivity. Therefore, in order to improve the sensitivity of grid peak regulation, while reducing operating and maintenance costs and reducing environmental impact, energy storage can be used to improve the flexibility and efficiency of grid peak regulation.

[0003] Traditional compressed air energy storage can handle large-scale, long-term energy storage needs, but its response speed and peak-shaving capacity are low. At the same time, a larger space is required to build the air storage unit, resulting in increased equipment and land costs, and higher facility construction and maintenance costs. Summary of the invention

[0004] In order to solve the technical problems of the slow response speed and low peak-shaving capacity of the above-mentioned traditional compressed air energy storage, and the need for a large space to build an air storage unit, the present invention provides a coal-biomass mixed combustion power grid peak-shaving system and method. The present invention provides a coal-biomass mixed combustion power grid peak-shaving system by combining compressed air energy storage technology, molten salt energy storage technology and energy recovery and utilization technology. The coal-biomass mixed combustion power grid peak-shaving system of the present invention can not only improve the utilization rate of fuel, but also significantly improve the flexibility and efficiency of power grid peak-shaving, reduce operation and maintenance costs, and reduce negative impacts on the environment.

[0005] The coal and biomass mixed combustion power grid peak load regulation system and method of the present invention is realized by the following technical solutions:

[0006] The first object of the present invention is to provide a power grid peak-shaving system using a combination of coal and biomass.

[0007] The present invention takes into account that traditional compressed air energy storage can handle large-scale long-term energy storage needs, but has low response speed and peak-shaving capacity, and requires a larger space to build air storage units, resulting in increased equipment costs and land costs, and high facility construction and maintenance costs. The present invention combines compressed air energy storage with molten salt energy storage technology and energy recovery technology, aiming to ensure fuel utilization while improving the peak-shaving sensitivity of the power grid, thereby reducing operation and maintenance costs. And the coal and biomass mixed combustion power grid peak-shaving system provided by the present invention specifically includes a feeding device, a silo, a boiler, a first steam turbine, a flue gas purification device, a molten salt energy storage system and a compressed air energy storage system.

[0008] In the present invention, the feeding device is used to supply coal raw materials and biomass raw materials.

[0009] The feed end of the silo is communicated with the discharge end of the feeding device to receive the coal raw material and the biomass raw material from the feeding device, and mix the coal raw material and the biomass raw material to form a mixed fuel.

[0010] The boiler is provided with a burner connected to the interior of the boiler; the feed end of the burner is connected to the output end of the silo through a feeding pipe, so that the mixed fuel enters the boiler through the feeding pipe for combustion, generating high-temperature flue gas, and at the same time, the water in the boiler absorbs heat to generate high-temperature and high-pressure steam.

[0011] The steam inlet of the first steam turbine is connected to the steam outlet of the boiler through a main steam pipe to receive high-temperature and high-pressure steam from the boiler, convert the thermal energy in the high-temperature and high-pressure steam into mechanical energy, and generate power to drive electricity generation.

[0012] The air inlet end of the flue gas purification device is connected to the exhaust end of the boiler through a flue to receive the high-temperature flue gas from the boiler, and the flue gas purification device removes harmful substances such as SO2, nitrogen oxides, particulate matter, etc. in the flue gas to achieve the expected effect, so that it is not easy to clog the pipeline during subsequent recycling. While ensuring that the flue gas emissions meet environmental protection standards, it can also improve the operating efficiency of the system and is also conducive to green environmental protection.

[0013] The molten salt energy storage system is used to receive and store heat from the flue gas purified by the flue gas purification device and the steam exhaust gas after being used by the first steam turbine.

[0014] The compressed air energy storage system is used to receive and store the energy of the gas after heat release and temperature reduction in the molten salt energy storage system.

[0015] The output end of the molten salt energy storage system and the output end of the compressed air energy storage system are connected to the steam inlet of the first steam turbine to provide a heat source for the operation of the first steam turbine.

[0016] During the low-peak period of electricity consumption, the power grid peak-shaving system of the present invention stores the heat and excess electric energy in the flue gas and the exhaust gas discharged by the first steam turbine in the molten salt energy storage system and the compressed air energy storage system respectively; during the peak period of electricity consumption: the stored heat and energy are released through the molten salt energy storage system and the compressed air energy storage system to generate electricity and supplement the power grid load.

[0017] In some preferred embodiments of the present invention, the molten salt energy storage system includes a low-temperature molten salt storage unit, a high-temperature molten salt storage unit, a molten salt delivery pipeline, an electric heater, a second heat exchange unit and a third heat exchange unit.

[0018] The input end of the second heat exchange unit is connected to the steam outlet of the first steam turbine and the exhaust end of the flue gas purification device, and the input end of the second heat exchange unit is connected to the output end of the low-temperature molten salt storage unit to receive the heat from the flue gas purified by the flue gas purification device and the heat in the steam exhaust gas after being used by the first steam turbine and the molten salt from the low-temperature molten salt storage unit, so that the molten salt and the heat are heat-exchanged to obtain high-temperature molten salt after heat absorption, flue gas after cooling, and steam exhaust gas after cooling. The flue gas outlet of the second heat exchange unit is connected to the chimney for directly discharging the cooled flue gas. The output end of the second heat exchange unit is connected to the input end of the electric heater, and the output end of the electric heater is connected to the input end of the high-temperature molten salt storage unit. During the low-peak period of electricity consumption, the low-temperature molten salt in the low-temperature molten salt storage unit enters the second heat exchange unit through the molten salt delivery pipeline to absorb heat and heat up for the first time. At the same time, the exhaust steam discharged from the turbine and the flue gas after purification also enter the second heat exchange unit through the pipeline to release heat and cool down; the molten salt after the first heating is heated for the second time through the electric heater, and then enters the high-temperature molten salt storage unit for storage, so that during the low-peak period of electricity consumption, the heat in the flue gas and steam and the excess electricity can be stored in the molten salt. The input end of the third heat exchange unit is connected to the output end of the high-temperature molten salt storage unit, the output end of the third heat exchange unit is connected to the input end of the low-temperature molten salt storage unit, and the water delivery end of the third heat exchange unit is also connected to a water source, and the steam outlet of the third heat exchange unit is connected to the input end of the first steam turbine. During peak electricity consumption, the high-temperature molten salt in the high-temperature molten salt storage unit enters the third heat exchange unit to release heat and cool down. At the same time, water enters the third heat exchange device to absorb heat and rise in temperature to become superheated steam. The generated superheated steam enters the first steam turbine through the steam outlet of the third heat exchange unit, and the molten salt after releasing heat in the third heat exchange unit enters the low-temperature molten salt storage unit through the first output end for storage.

[0019] In a preferred embodiment of the present invention, the compressed air energy storage system includes a compressor, a fourth heat exchange unit, a high-pressure gas storage unit and a second steam turbine. Among them, the input end of the compressor is connected to the exhaust end of the second heat exchange unit, and the input end of the compressor is also connected to an air source, the output end of the compressor is connected to the input end of the fourth heat exchange unit, the output end of the fourth heat exchange unit is connected to the high-pressure gas storage unit, the output end of the fourth heat exchange unit is connected to the input end of the first steam turbine, and the high-pressure gas storage unit is connected to the second steam turbine. During the low-peak period of electricity consumption, a small amount of extra electricity is stored in the above-mentioned molten salt energy storage system, while most of the extra electricity is stored in the compressed air energy storage system. The gas after heat release and temperature reduction in the second heat exchange unit is mixed with air through a pipeline and enters the compressor. The gas temperature and pressure increase, and the gas after temperature increase and pressure increase enters the fourth heat exchange unit to release heat and cool down; at the same time, water enters the fourth heat exchange unit to absorb heat and heat up to become superheated steam. The heated superheated steam enters the input end of the first steam turbine from the output end of the fourth heat exchange unit. The gas released from the fourth heat exchange unit enters the high-pressure gas storage unit for storage. During peak hours of electricity consumption, the energy stored in the compressed air energy storage system is converted into electrical energy output. The gas in the high-pressure gas storage unit enters the second steam turbine to generate electricity.

[0020] In a preferred embodiment of the present invention, the power grid peak load regulation system further comprises a first heat exchange unit, the air inlet end of the first heat exchange unit is connected to the exhaust end of the flue gas purification device, and the steam inlet of the first heat exchange unit is connected to the steam outlet of the first steam turbine, so as to receive heat from the flue gas purified by the flue gas purification device and the steam exhaust gas after being used by the first steam turbine. The water inlet end of the first heat exchange unit is also connected to a water source, and the steam outlet of the first heat exchange unit is connected to the steam inlet of the first steam turbine, so that during the peak period of electricity consumption, after water is input to the water inlet end of the first heat exchange unit, the water enters the first heat exchange unit to absorb the heat from the flue gas purified by the flue gas purification device and the steam exhaust gas after being used by the first steam turbine, and then is converted into superheated steam, and the superheated steam enters the first steam turbine to provide a heat source for the operation of the first steam turbine.

[0021] In some preferred embodiments of the present invention, the inlet end of the feed pipe is connected to a first fan, which provides primary air to the feed pipe, carries the mixed fuel in the feed pipe into the burner, and provides the required oxygen for the combustion of the fuel.

[0022] In some preferred embodiments of the present invention, the boiler is provided with a secondary air inlet, and the secondary air inlet is provided with a second fan, and the second fan is used to provide secondary air to the secondary air inlet to provide additional oxygen for the combustion of the fuel and promote the complete combustion of the fuel.

[0023] In some preferred embodiments of the present invention, the power grid peak-shaving system further includes a flow regulation system and an energy management system, wherein the flow regulation system includes a plurality of flow control units, and the plurality of flow control units are respectively used to control the flow of each corresponding material transport process. The energy management system includes a data processing module and a control signal output module, wherein the data processing module is used to receive power supply and demand data, and the control signal output module is connected to the plurality of flow control units to output control signals according to the power supply and demand data to control the working states of the plurality of flow control units respectively, so as to realize intelligent peak-shaving of the power grid.

[0024] In some preferred embodiments of the present invention, the feeding device includes a coal powder feeding unit and a biomass feeding unit, wherein the coal powder feeding unit is used to store coal raw materials, and the biomass feeding unit is used to store biomass raw materials. The discharge end of the coal powder feeding unit and the discharge end of the biomass feeding unit are both connected to the feed end of the silo to provide the coal raw materials and the biomass raw materials to the silo.

[0025] In some preferred embodiments of the present invention, a first flow control unit is provided between the discharge end of the coal powder feeding unit and the feed end of the silo, and the first flow control unit is used to regulate the feed flow rate of the coal raw material.

[0026] In some preferred embodiments of the present invention, a second flow control unit is provided between the discharge end of the biomass feeding unit and the feed end of the silo, and the second flow control unit is used to adjust the feed flow rate of the biomass.

[0027] In some preferred embodiments of the present invention, a third flow control unit is provided between the discharge end of the silo and the feed end of the burner, and the third flow control unit is used to regulate the feed flow rate of the mixed fuel formed by mixing coal raw material and biomass raw material entering the burner.

[0028] In some preferred embodiments of the present invention, a fourth flow control unit is provided between the air outlet of the primary fan and the input end of the feeding pipe, and the fourth flow control unit is used to regulate the primary air flow rate entering the feeding pipe.

[0029] In some preferred embodiments of the present invention, a fifth flow control unit is provided between the air outlet of the secondary fan and the secondary air outlet, and the fifth flow control unit is used to regulate the size of the secondary flow entering the boiler.

[0030] In some preferred embodiments of the present invention, a sixth flow control unit is provided between the output end of the low-temperature molten salt storage unit and the input end of the second heat exchange unit, and the sixth flow control unit is used to adjust the output flow of the molten salt in the low-temperature molten salt storage unit.

[0031] In some preferred embodiments of the present invention, a seventh flow control unit is arranged between the input end of the third heat exchange unit and the output end of the high-temperature molten salt storage unit, and the seventh flow control unit is used to control the output flow rate of the high-temperature molten salt in the high-temperature molten salt storage unit to the third heat exchange unit.

[0032] In some preferred embodiments of the present invention, an eighth flow control unit is provided between the steam inlet of the first heat exchange unit and the steam outlet of the first steam turbine, so as to control the steam flow entering the first heat exchange unit through the eighth flow control unit.

[0033] In some preferred embodiments of the present invention, a ninth flow control unit is provided between the air inlet end of the first heat exchange unit and the exhaust end of the flue gas purification device, so as to control the flue gas flow entering the first heat exchange unit through the ninth flow control unit.

[0034] In some preferred embodiments of the present invention, a tenth flow control unit is provided between the exhaust end of the flue gas purification device and the input end of the second heat exchange unit, so as to control the heat amount of the flue gas entering the second heat exchange unit through the tenth flow control unit.

[0035] In some preferred embodiments of the present invention, an eleventh flow control unit is arranged between the steam outlet of the first steam turbine and the input end of the second heat exchange unit, so as to control the amount of heat in the steam exhaust gas after being used by the first steam turbine and entering the second heat exchange unit through the eleventh flow control unit.

[0036] In some preferred embodiments of the present invention, a twelfth flow control unit is provided between the air source and the input end of the compressor, so as to control the flow rate of the air entering the compressor through the twelfth flow control unit.

[0037] In some preferred embodiments of the present invention, a thirteenth flow control unit is provided between the output end of the compressor and the input end of the fourth heat exchange unit, so as to control the flow rate of compressed air entering the fourth heat exchange unit through the thirteenth flow control unit.

[0038] In some preferred embodiments of the present invention, a fourteenth flow control unit is provided between the output end of the fourth heat exchange unit and the input end of the high-pressure gas storage unit, so as to control the flow rate of the high-pressure air after heat exchange entering the high-pressure gas storage unit through the fourteenth flow control unit.

[0039] In some preferred embodiments of the present invention, a fifteenth flow control unit is provided between the output end of the high-pressure air storage unit and the input end of the second steam turbine, so as to control the flow rate of the high-pressure air entering the second steam turbine through the fifteenth flow control unit.

[0040] In some preferred embodiments of the present invention, the flue gas purification system includes a pretreatment device, a desulfurization device, a denitrification device, a carbon dioxide capture device and a particle capture device. After preliminary treatment by the treatment device, the flue gas passes through the pretreatment device, the desulfurization device, the denitrification device, the carbon dioxide capture device and the particle capture device at one time, effectively removing large particles, sulfur dioxide, nitrogen oxides, carbon dioxide and other solid particles in the flue gas, while ensuring that the flue gas emissions meet environmental protection standards, and can also integrate various purification devices to improve the purification efficiency of the system.

[0041] A second object of the present invention is to provide a power grid peak shaving method based on the above-mentioned power grid peak shaving system of coal and biomass co-combustion, comprising the following steps:

[0042] Step 1: conveying coal raw materials and biomass raw materials into the silo through the feeding device.

[0043] Step 2: The silo mixes the coal raw material and the biomass raw material, and then transports the mixed materials into the boiler through a feeding pipe for combustion, thereby generating high-temperature flue gas and high-temperature and high-pressure steam.

[0044] Step 3, transporting the high-temperature and high-pressure steam through the main steam pipeline into the first steam turbine for use to generate steam exhaust gas.

[0045] Step 4, when the electricity consumption is at a low peak period, the high-temperature flue gas generated by the boiler, the heat in the steam exhaust gas after use of the first steam turbine, and the excess electric energy are stored in the molten salt energy storage system and the compressed air energy storage system respectively.

[0046] Step 5: When electricity consumption is at its peak, the heat and energy stored in the molten salt energy storage system and the compressed air energy storage system are released to generate electricity and supplement the grid load.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The molten salt energy storage system of the present invention can achieve rapid charging and discharging. The molten salt energy storage system uses molten salt as a heat storage medium, has high heat capacity and stable chemical properties, can quickly absorb and release heat, thereby achieving rapid charging and discharging. Moreover, it combines the long-term energy storage capacity of compressed air energy storage. Compared with traditional compressed air energy storage systems, it significantly improves the sensitivity of power grid peak regulation and can better cope with fluctuations in electricity demand. When electricity demand is low, the system can store excess heat and electrical energy in molten salt; when electricity demand is high, the system can release the stored heat and electrical energy and convert it into electrical energy output, thereby achieving rapid peak regulation of the power grid.

[0049] The present invention further improves the efficiency of energy utilization and achieves the goal of energy conservation and emission reduction by recycling flue gas waste heat and turbine exhaust gas. Both flue gas waste heat and turbine exhaust gas contain a large amount of thermal energy, and directly discharging them into the environment will cause energy waste. The present invention recycles the heat in flue gas waste heat and turbine exhaust gas through a heat exchange device, and uses it to heat water in the boiler and convert it into superheated steam, thereby increasing the steam output of the boiler and increasing the power generation. At the same time, recycling flue gas waste heat and turbine exhaust gas can also reduce the heat loss of the system and further improve the efficiency of energy utilization.

[0050] The present invention removes harmful substances such as SO2, nitrogen oxides, particulate matter, etc. in the flue gas through a flue gas purification system to achieve the expected effect, so that it is not easy to clog the pipeline during subsequent recycling. While ensuring that the flue gas emissions meet environmental protection standards, it can also improve the operating efficiency of the system and is also beneficial to green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A schematic diagram of a power grid peak-shaving system for coal and biomass co-combustion with intelligent control provided in one embodiment of the present invention; Figure 1The reference numerals in the figure are: 1-coal powder feeding unit; 2-biomass feeding unit; 3-first flow control unit; 4-second flow control unit; 5-silo; 6-third flow control unit; 7-fourth flow control unit; 8-fifth flow control unit; 9-secondary air inlet; 10-burner; 11-feeding pipe; 12-boiler; 13-main steam pipeline; 14-first steam turbine; 15-flue gas purification device; 16-flue; 17-first heat exchange unit; 18-low-temperature molten salt storage unit; 19-high-temperature molten salt storage unit; 20-second heat exchange unit; 21-third heat exchange unit; 22 -molten salt delivery pipeline; 23-electric heater; 24-sixth flow control unit; 25-seventh flow control unit; 26-compressor; 27-fourth heat exchange unit; 28-high-pressure gas storage unit; 29-second steam turbine; 30-eighth flow control unit; 31-ninth flow control unit; 32-tenth flow control unit; 33-eleventh flow control unit; 34-twelfth flow control unit; 35-thirteenth flow control unit; 36-fourteenth flow control unit; 37-fifteenth flow control unit; 38-energy management system; 39-first fan; 40-second fan.

[0052] Figure 2 A schematic diagram of the connection relationship of the energy management system of the present invention; Figure 2 The reference numerals in the drawings are: 38 - energy management system, 381 - data processing module, 382 - control signal output module. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present invention will be described clearly and completely below.

[0054] Traditional compressed air energy storage can handle large-scale long-term energy storage needs, but its response speed and peak-shaving capacity are low, and it requires a larger space to build air storage units, resulting in increased equipment and land costs, and higher facility construction and maintenance costs. The present invention combines compressed air energy storage with molten salt energy storage technology and energy recovery technology, aiming to ensure fuel utilization while improving the peak-shaving sensitivity of the power grid, thereby reducing operation and maintenance costs.

[0055] Example 1

[0056] Combination Figure 1 As shown, this embodiment provides a power grid peak-shaving system that burns a mixture of coal and biomass.

[0057] The coal and biomass mixed combustion power grid peak load regulation system of this embodiment includes a feeding device, a silo 5, a boiler 12, a first steam turbine 14, a flue gas purification device 15, a molten salt energy storage system and a compressed air energy storage system.

[0058] See also Figure 1In this embodiment, the feeding device includes a coal powder feeding unit 1 and a biomass feeding unit 2, wherein the outlet of the coal powder feeding unit 1 and the outlet of the biomass feeding unit 2 are both connected to the silo 5, so that the coal powder feeding unit 1 provides the coal powder stored therein to the silo 5, and the biomass feeding unit 2 provides the biomass stored therein to the silo 5, so as to facilitate mixing of the coal and biomass raw materials through the silo 5.

[0059] In this embodiment, a burner 10 connected to the inside of the boiler 12 is provided on the boiler 12, and the feed end of the burner 10 is connected to the output end of the silo 5 through a feeding pipe 11, that is, the feeding pipe 11 is a channel connecting the silo 5 and the burner 10 of the boiler 12, and is used to transport the mixed coal and biomass fuel in the silo 5 to the burner 10 of the boiler 12, so that the mixed fuel enters the boiler 12 through the feeding pipe 11 for combustion, generating high-temperature flue gas, and at the same time, the water in the boiler 12 absorbs heat to generate high-temperature and high-pressure steam.

[0060] In this embodiment, the steam inlet of the first steam turbine 14 is connected to the steam outlet of the boiler 12 through the main steam pipe 13 to receive high-temperature and high-pressure steam from the boiler 12. The air inlet end of the flue gas purification device 15 is connected to the exhaust end of the boiler 12 through the flue 16 to receive and purify the high-temperature flue gas from the boiler 12.

[0061] Specifically, when coal and biomass are mixed and burned, the coal fuel in the coal powder feeding unit 1 and the biomass fuel in the biomass feeding unit 2 enter the silo 5 and are mixed evenly, the mixed fuel in the silo 5 enters the feeding pipe 11, the primary air enters the feeding pipe 11, and carries the mixed fuel into the burner 10, and the control system starts the burner 10 to ignite, and then the mixed fuel is sprayed into the boiler 12 for combustion, the primary air is mixed with the fuel through the feeding pipe 11, and helps the fuel to form a proper airflow for combustion; at the same time, the secondary air is sent to the boiler 12 through the secondary air port 9, and further mixed with the mixed fuel sprayed from the burner 10, and provides additional oxygen to promote the full combustion of the fuel. The flue gas generated by the mixed combustion of coal and biomass enters the flue gas purification device 15, and the high-temperature and high-pressure steam converted by the water in the boiler 12 absorbs heat enters the first steam turbine 14 through the main steam pipe 13, converting the thermal energy into mechanical energy, generating power to drive power generation.

[0062] On the basis of the above-mentioned implementation mode, in order to realize the intelligent peak-shaving of the power grid, so as to further utilize the heat in the high-temperature and high-pressure steam and high-temperature flue gas generated above, the molten salt energy storage system in this embodiment is used to receive and store the heat from the flue gas purified by the flue gas purification device 15 and the steam exhaust gas after being used by the first steam turbine 14. The power grid peak-shaving system of this embodiment also includes a molten salt energy storage system, a compressed air energy storage system, a first heat exchange unit 17, and an energy management system 38. Among them, the molten salt energy storage system is used to receive and store the heat from the flue gas purified by the flue gas purification device 15 and the steam exhaust gas after being used by the first steam turbine 14. The compressed air energy storage system is used to receive and store the energy of the gas after heat release and cooling in the molten salt energy storage system. And the output end of the molten salt energy storage system and the output end of the compressed air energy storage system are connected to the steam inlet of the first steam turbine 14 to provide a heat source for the operation of the first steam turbine 14.

[0063] In a preferred embodiment of the present invention, the molten salt energy storage system includes a low-temperature molten salt storage unit 18, a high-temperature molten salt storage unit 19, a second heat exchange unit 20, a third heat exchange unit 21, a molten salt delivery pipeline 22, and an electric heater 23. Among them, this embodiment also includes a solar collector to collect solar radiation energy and convert it into heat energy or an electric heater uses electrical energy to heat the low-temperature molten salt.

[0064] In a preferred embodiment of the present invention, the compressed air energy storage system includes a compressor 26, a fourth heat exchange unit 27, a high-pressure gas storage unit 28 and a second steam turbine 29. The input end of the compressor 26 is connected to the exhaust end of the second heat exchange unit 20 through a pipeline, and the input end of the compressor 26 is also connected to an air source, so that the gas after heat release and cooling in the second heat exchange unit 20 is mixed with air and enters the compressor 26 for compression. The input end of the fourth heat exchange unit 27 is connected to the output end of the compressor 26 through a pipeline, and the water supply end of the fourth heat exchange unit 27 is also connected to a water source, so that the compressed gas enters the fourth heat exchange unit 27 to release heat and supply water, and the water absorbs heat and rises to become superheated steam; the input end of the high-pressure gas storage unit 28 is connected to the exhaust end of the fourth heat exchange unit 27 to receive and store the gas after heat release in the fourth heat exchange unit 27. The input end of the second steam turbine 29 is connected to the output end of the high-pressure gas storage unit 28, so that the gas in the high-pressure gas storage unit 28 enters the second steam turbine 29 to generate power.

[0065] In a preferred embodiment of the present invention, the power grid peak load regulation system further includes a first heat exchange unit 17, the air inlet end of the first heat exchange unit 17 is connected to the exhaust end of the flue gas purification device 15, and the steam inlet of the first heat exchange unit 17 is connected to the steam outlet of the first steam turbine 14, so as to receive heat from the flue gas purified by the flue gas purification device 15 and the steam exhaust gas after being used by the first steam turbine 14. The water inlet end of the first heat exchange unit 17 is also connected to a water source, and the steam inlet of the first heat exchange unit 17 is connected to the steam outlet of the first steam turbine 14, so that water enters the first heat exchange unit 17 to absorb the heat from the flue gas purified by the flue gas purification device 15 and the steam exhaust gas after being used by the first steam turbine 14, and then is converted into superheated steam, and the superheated steam enters the first steam turbine 14 to provide a heat source for the operation of the first steam turbine 14.

[0066] In this embodiment, the output end of the low-temperature molten salt storage unit 18 is connected to the first input end of the second heat exchange unit 20; the second input end of the second heat exchange unit 20 is connected to the exhaust gas channel, and the exhaust gas discharged by the first steam turbine 14 and the flue gas discharged by the flue gas purification device 15 both enter the second input end of the second heat exchange unit 20 through the exhaust gas channel. During the low-peak period of electricity consumption, the first steam turbine 14 uses the high-temperature and high-pressure steam generated by the boiler 12 to do work, which will produce exhaust steam. These exhaust steam and the flue gas discharged by the flue gas purification device 15 still contain a large amount of heat, which is directly transported to the second input end of the second heat exchange unit 20 through the exhaust steam channel. Here, the high-temperature gas exchanges heat with the low-temperature molten salt, transfers the heat to the low-temperature molten salt, and then the gas enters the compressor 26 to further utilize the remaining heat. The first output end of the second heat exchange unit 20 is connected to the input end of the electric heater 23; the output end of the electric heater 23 is connected to the input end of the high-temperature molten salt storage unit 19; the output end of the high-temperature molten salt storage unit 19 is connected to the first input end of the third heat exchange unit 21; the first output end of the third heat exchange unit 21 is connected to the input end of the low-temperature molten salt storage unit 18.

[0067] Specifically, during the off-peak period of electricity consumption, the system can store the heat in the flue gas and steam and the excess electricity in the molten salt. The low-temperature molten salt in the low-temperature molten salt storage unit 18 enters the second heat exchange unit 20 through the molten salt delivery pipeline 22 for the first heat absorption and temperature increase. At the same time, the exhaust steam discharged from the turbine and the flue gas after purification also enter the second heat exchange unit 20 through the pipeline to release heat and cool down; the molten salt after the first temperature increase is heated for the second time through the electric heater 23, and then enters the high-temperature molten salt storage unit 19 for storage. During the peak period of electricity consumption, the molten salt energy storage system will release the stored heat for power generation. The high-temperature molten salt in the high-temperature molten salt storage unit 19 enters the third heat exchange unit 21 for heat release and temperature reduction; at the same time, water also enters the third heat exchange device 21 for heat absorption and temperature increase to become superheated steam, and the superheated steam is output from the second output end of the third heat exchange unit 21 and enters the input end of the first steam turbine 14; the molten salt after heat release in the third heat exchange unit 21 enters the low-temperature molten salt storage unit 18 for storage through the first output end.

[0068] During the peak period of electricity consumption, the exhaust gas discharged from the first steam turbine 14 and the flue gas purified in the flue gas purification device 15 enter the first heat exchange unit 17 to release heat. At the same time, water enters the first heat exchange unit 17 to absorb heat and convert into superheated steam. The superheated steam is output through the first output end of the first heat exchange unit 17 and then enters the input end of the first steam turbine 14. The exhaust gas after heat release is discharged through the second output end of the first heat exchange unit 17 and enters the chimney.

[0069] In a preferred embodiment of the present invention, in order to ensure that the fuel can be smoothly fed from the silo 5 into the burner 10 and fully mixed with the air in the burner 10, it is necessary to provide power through a fan. The end of the feed pipe 11 away from the burner 10 is connected to the first fan 39, and the first fan 39 is used to provide primary air to the feed pipe 11. The second fan 40 is connected to the secondary air port 9 on the boiler 12 through a pipeline, and the second fan 40 is used to provide secondary air to the secondary air port 9.

[0070] In a preferred embodiment of the present invention, the boiler 12 is provided with a secondary air port 9, and the secondary air port 9 is provided with a second fan 40, and the second fan 40 is used to provide secondary air to the secondary air port 9, to provide additional oxygen for the combustion of the fuel, and to promote the complete combustion of the fuel.

[0071] In a preferred embodiment of the present invention, the silo 5 is equipped with a stirring device to fully mix the biomass raw material.

[0072] See also Figure 1 and Figure 2In a preferred embodiment of the present invention, the power grid peak load regulation system further includes an energy management system 38. The energy management system 38 includes a data processing module 381 and a control signal output module 382. The data processing module 381 is used to receive power supply and demand data. The control signal output module 382 is connected to a plurality of flow control units to output control signals according to the power supply and demand data to control the working states of the plurality of flow control units.

[0073] On the basis of the above-mentioned implementation mode, in order to facilitate the adjustment of the blending ratio of coal and biomass, the amount of mixed fuel, the primary air volume and the secondary air volume, as well as the heat exchange effect, in a preferred embodiment of the present invention, the power grid peak-shaving system of the present invention also includes a flow regulation system, and the flow regulation system includes a first flow control unit 3, a second flow control unit 4, a third flow control unit 6, a fourth flow control unit 7, a fifth flow control unit 8, a sixth flow control unit 24, a seventh flow control unit 25, an eighth flow control unit 30, a ninth flow control unit 31, a tenth flow control unit 32, an eleventh flow control unit 33, a twelfth flow control unit 34, a thirteenth flow control unit 35, a fourteenth flow control unit 36 ​​and a fifteenth flow control unit 37.

[0074] Specifically, a first flow control unit 3 is provided between the discharge end of the coal powder feeding unit 1 and the feed end of the silo 5, and the first flow control unit 3 is used to adjust the feed flow rate of the coal raw material.

[0075] In some preferred embodiments of the present invention, a second flow control unit 4 is provided between the discharge end of the biomass feeding unit 2 and the feed end of the silo 5, and the second flow control unit 4 is used to adjust the feed flow rate of the biomass.

[0076] In some preferred embodiments of the present invention, a third flow control unit 6 is provided between the discharge end of the silo 5 and the feed end of the burner 10, and the third flow control unit 6 is used to regulate the feed flow rate of the mixed fuel formed by mixing coal raw material and biomass raw material entering the burner.

[0077] In some preferred embodiments of the present invention, a fourth flow control unit 7 is provided between the air outlet of the primary fan 39 and the input end of the feeding pipe 11, and the fourth flow control unit 7 is used to regulate the primary air flow rate entering the feeding pipe.

[0078] In some preferred embodiments of the present invention, a fifth flow control unit 8 is provided between the air outlet of the secondary fan 39 and the secondary air outlet 9 , and the fifth flow control unit 8 is used to adjust the secondary flow entering the boiler 12 .

[0079] In some preferred embodiments of the present invention, a sixth flow control unit 24 is provided between the output end of the low-temperature molten salt storage unit 18 and the input end of the second heat exchange unit 20, and the sixth flow control unit 24 is used to adjust the output flow of the molten salt in the low-temperature molten salt storage unit.

[0080] In some preferred embodiments of the present invention, a seventh flow control unit 25 is arranged between the input end of the third heat exchange unit 21 and the output end of the high-temperature molten salt storage unit 19, and the seventh flow control unit 25 is used to control the output flow rate of the high-temperature molten salt in the high-temperature molten salt storage unit 19 to the third heat exchange unit 21.

[0081] In some preferred embodiments of the present invention, an eighth flow control unit 30 is provided between the steam inlet of the first heat exchange unit 17 and the steam outlet of the first steam turbine 14 to control the steam flow entering the first heat exchange unit 17 through the eighth flow control unit 30.

[0082] In some preferred embodiments of the present invention, a ninth flow control unit 31 is provided between the air inlet end of the first heat exchange unit 17 and the exhaust end of the flue gas purification device 15 so as to control the flue gas flow entering the first heat exchange unit 17 through the ninth flow control unit 31.

[0083] In some preferred embodiments of the present invention, a tenth flow control unit 32 is provided between the exhaust end of the flue gas purification device 15 and the input end of the second heat exchange unit 20, so as to realize the regulation of the heat amount of the flue gas entering the second heat exchange unit through the tenth flow control unit 32.

[0084] In some preferred embodiments of the present invention, an eleventh flow control unit 33 is provided between the steam outlet of the first steam turbine 14 and the input end of the second heat exchange unit 20, so as to control the amount of heat in the steam exhaust gas after being used by the first steam turbine 14 and entering the second heat exchange unit 20 through the eleventh flow control unit 33.

[0085] In some preferred embodiments of the present invention, a twelfth flow control unit 33 is provided between the air source and the input end of the compressor 26 , so as to control the flow rate of the air entering the compressor 26 through the twelfth flow control unit 33 .

[0086] In some preferred embodiments of the present invention, a thirteenth flow control unit 35 is provided between the output end of the compressor 26 and the input end of the fourth heat exchange unit 27 to control the flow of compressed air entering the fourth heat exchange unit 27 through the thirteenth flow control unit 35.

[0087] In some preferred embodiments of the present invention, a fourteenth flow control unit 36 ​​is provided between the output end of the fourth heat exchange unit 27 and the input end of the high-pressure air storage unit 28, so as to control the flow rate of the high-pressure air after heat exchange entering the high-pressure air storage unit 28 through the fourteenth flow control unit 36.

[0088] In some preferred embodiments of the present invention, a fifteenth flow control unit 37 is provided between the output end of the high-pressure air storage unit 28 and the input end of the second steam turbine 29 to control the flow rate of the high-pressure air entering the second steam turbine 29 through the fifteenth flow control unit 37.

[0089] On the basis of the above-mentioned implementation mode, the system can flexibly adjust the amount of coal and biomass, as well as the primary air volume and the secondary air volume, to achieve the desired effect. The flue gas generated by the combustion of the mixed fuel in the boiler 12 is sent to the purification system 15 for purification to remove harmful substances such as SO2, nitrogen oxides, and particulate matter in the flue gas, so that it is not easy to block the pipeline in the subsequent recycling, and no toxic gas is discharged, which is beneficial to green environmental protection.

[0090] In order to realize intelligent control of power grid peak regulation, after the energy management system 38 receives and processes the power supply and demand data, when the power supply is greater than the power demand, it outputs a control signal to close the seventh flow control unit 25, the eighth flow control unit 30, the ninth flow control unit 31, and the fifteenth flow control unit 37, and open the sixth flow control unit 24, the tenth flow control unit 32, the eleventh flow control unit 33, the twelfth flow control unit 34, the thirteenth flow control unit 35, and the fourteenth flow control unit 36; when the power demand is greater than the power supply, the energy management system 38 outputs a control signal to close the sixth flow control unit 24, the tenth flow control unit 32, the eleventh flow control unit 33, the twelfth flow control unit 34, the thirteenth flow control unit 35, and the fourteenth flow control unit 36, and close the seventh flow control unit 25, the eighth flow control unit 30, the ninth flow control unit 31, and the fifteenth flow control unit 37.

[0091] This embodiment provides a method for peak load regulation of a power grid by coupling molten salt with compressed air energy storage using a mixture of coal and biomass, comprising the following steps:

[0092] Step 1: convey coal raw materials and biomass raw materials into the silo 5 through the coal powder feeding unit 1 and the biomass feeding unit 2.

[0093] Step 2: After the coal raw material and the biomass raw material are mixed through the silo 5, they are transported into the boiler 12 through the feeding pipe 11 for combustion to generate high-temperature flue gas and high-temperature and high-pressure steam.

[0094] Step 3, transporting the high-temperature and high-pressure steam through the main steam pipeline 13 into the first steam turbine 14 for use, generating steam exhaust gas.

[0095] When electricity consumption is at a low peak, the high-temperature flue gas generated by the boiler 12, the heat in the steam exhaust gas after use by the first steam turbine 14, and a small amount of excess electricity are stored in the molten salt energy storage system, while most of the excess heat is stored in the compressed air energy storage system.

[0096] When electricity consumption is at its peak, the heat in the high-temperature flue gas and the exhaust gas from the turbine is recovered into the water vapor in the boiler through a heat exchanger. At the same time, the molten salt energy storage system and the compressed air energy storage system convert the stored energy into electrical energy for power generation and to supplement the grid load.

[0097] The present invention uses molten salt energy storage technology and compressed air energy storage technology, combined with intelligent peak-shaving technology, to store and release energy using the heat storage and heat release cycle of molten salt according to the peak value of the power grid, to achieve effective energy migration, improve the intermittent and instability of the new power system, store excess electrical energy and thermal energy during low-peak electricity consumption, and release these energies during peak electricity consumption to meet electricity demand, significantly improving the flexibility of power grid peak-shaving. In addition, the heat exchange device is used to recycle the heat in the flue gas and the exhaust gas of the steam turbine, which increases the power generation while reducing the heat loss of the system, further improving the energy utilization efficiency, and reducing greenhouse gas emissions and external energy demand.

[0098] The present invention achieves the optimal operating state through intelligent regulation and control, and has high efficiency, economy and operability. The system that couples compressed air energy storage and molten salt energy storage can take advantage of the advantages of both and provide a more efficient and flexible energy storage solution. Compressed air energy storage can handle large-scale long-term energy storage needs, while molten salt energy storage can handle rapid charging and discharging needs in a short period of time. Compared with the instability and scenario limitations of traditional technologies, the system is more flexible in dealing with fluctuations in electricity demand, provides a more stable power supply, helps to balance the load of the power grid, reduces the pressure of peak load on the power grid, improves the operating efficiency and reliability of the power grid, and can balance the advantages and disadvantages of the two technologies under different load conditions. In addition, the system further optimizes the heat storage medium and uses low-melting point mixed molten salt to increase the heat storage temperature and reduce costs; in the design and operation of the system, environmental impacts are considered, such as using renewable energy such as solar energy as a heat source to reduce dependence on fossil fuels, and has broad application prospects and huge development potential.

[0099] Obviously, the above embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A coal-biomass mixed combustion power grid peak shaving system, the power grid peak shaving system is used in a boiler system, characterized in that: The power grid peak load regulation system comprises: A feeding device, used for supplying coal raw materials and biomass raw materials; A silo (5), whose feeding end is connected to the discharging end of the feeding device, so as to receive the coal raw material and the biomass raw material from the feeding device and mix the coal and the biomass to form a mixed fuel; A boiler (12) is provided with a burner (10) which is in communication with the interior of the boiler (12); the feed end of the burner (10) is in communication with the output end of the silo (5) via a feed pipe (11), so that the mixed fuel enters the boiler (12) through the feed pipe (11) for combustion, thereby generating high-temperature flue gas, and at the same time, water in the boiler (12) absorbs heat to generate high-temperature and high-pressure steam; a first steam turbine (14), the steam inlet of which is connected to the steam outlet of the boiler (12) through a main steam pipe (13) so as to receive high-temperature and high-pressure steam from the boiler (12); a flue gas purification device (15), the air inlet end of which is connected to the exhaust end of the boiler (12) via a flue (16) so as to receive and purify the high-temperature flue gas from the boiler (12); a molten salt energy storage system, used for receiving and storing heat from flue gas purified by the flue gas purification device (15) and steam exhaust gas after being used by the first steam turbine (14); A compressed air energy storage system, used to receive and store the energy of the gas after heat release and temperature reduction in the molten salt energy storage system; The output end of the molten salt energy storage system and the output end of the compressed air energy storage system are connected to the steam inlet of the first steam turbine (14) to provide a heat source for the operation of the first steam turbine (14).

2. The power grid peak load regulation system for coal and biomass co-combustion according to claim 1, characterized in that: The molten salt energy storage system comprises a low-temperature molten salt storage unit (18), a high-temperature molten salt storage unit (19), a second heat exchange unit (20), a third heat exchange unit (21), a molten salt transport pipeline (22) and an electric heater (23); The input end of the second heat exchange unit (20) is connected to the steam outlet of the first steam turbine (14) and the exhaust end of the flue gas purification device (15), and the input end of the second heat exchange unit (20) is connected to the output end of the low-temperature molten salt storage unit (18) through a molten salt delivery pipeline (22); The output end of the second heat exchange unit (20) is in communication with the input end of the electric heater (23), and the output end of the electric heater (23) is in communication with the input end of the high-temperature molten salt storage unit (19); The input end of the third heat exchange unit (21) is connected to the output end of the high-temperature molten salt storage unit (19), and the output end of the third heat exchange unit (21) is connected to the input end of the low-temperature molten salt storage unit (18); The water supply end of the third heat exchange unit (21) is also connected to a water source, and the steam outlet of the third heat exchange unit (21) is connected to the input end of the first steam turbine (14).

3. The power grid peak load regulation system for coal and biomass co-combustion according to claim 2, characterized in that: The compressed air energy storage system comprises a compressor (26), a fourth heat exchange unit (27), a high-pressure air storage unit (28) and a second steam turbine (29); The input end of the compressor (26) is connected to the exhaust end of the second heat exchange unit (20) through a pipeline, and the input end of the compressor (26) is also connected to an air source, so that the gas after heat release and temperature reduction in the second heat exchange unit (20) is mixed with air and then enters the compressor (26) for compression processing; The input end of the fourth heat exchange unit (27) is connected to the output end of the compressor (26) through a pipeline, and the water supply end of the fourth heat exchange unit (27) is also connected to a water source, so that the compressed gas enters the fourth heat exchange unit (27) to release heat and supply water, and the water absorbs heat and rises in temperature to become superheated steam; The input end of the high-pressure gas storage unit (28) is connected to the exhaust end of the fourth heat exchange unit (27) to receive and store the gas after the fourth heat exchange unit (27) releases heat; The input end of the second steam turbine (29) is connected to the output end of the high-pressure gas storage unit (28), so that the gas in the high-pressure gas storage unit (28) enters the second steam turbine (29) to generate power.

4. The power grid peak load regulation system for coal and biomass co-combustion according to claim 1, characterized in that: The power grid peak load regulation system further comprises a first heat exchange unit (17), an air inlet end of the first heat exchange unit (17) being in communication with an exhaust end of the flue gas purification device (15), and a steam inlet of the first heat exchange unit (17) being in communication with a steam outlet of the first steam turbine (14) so ​​as to receive heat from the flue gas purified by the flue gas purification device (15) and from the steam exhaust gas after being used by the first steam turbine (14); The water inlet end of the first heat exchange unit (17) is also connected to a water source, and the steam outlet of the first heat exchange unit (17) is connected to the steam inlet of the first steam turbine (14), so that water enters the first heat exchange unit (17) to absorb heat from the flue gas purified by the flue gas purification device (15) and the steam exhaust gas after being used by the first steam turbine (14), and then is converted into superheated steam. The superheated steam enters the first steam turbine (14) to provide a heat source for the operation of the first steam turbine (14).

5. The power grid peak load regulation system for coal and biomass co-combustion according to claim 4, characterized in that: An eighth flow control unit (30) is provided between the steam inlet of the first heat exchange unit (17) and the steam outlet of the first steam turbine (14); A ninth flow control unit (31) is provided between the air inlet end of the first heat exchange unit (17) and the exhaust end of the flue gas purification device (15).

6. The power grid peak load regulation system for coal and biomass co-combustion according to claim 1, characterized in that: The inlet end of the feed pipe (11) is connected to a first fan (39), which provides primary air to the feed pipe (11), carries the mixed fuel in the feed pipe (11) into the burner (10), and provides the required oxygen for the combustion of the fuel.

7. The power grid peak load regulation system for coal and biomass co-combustion according to claim 1, characterized in that: The boiler (12) is provided with a secondary air port (9), and the secondary air port (9) is provided with a second fan (40), and the second fan (40) is used to provide secondary air to the secondary air port (9), thereby providing additional oxygen for the combustion of the fuel and promoting the complete combustion of the fuel.

8. The power grid peak load regulation system for coal and biomass co-combustion according to claim 1, characterized in that: The power grid peak regulation system also includes a flow regulation system and an energy management system (38); The flow regulation system includes a plurality of flow control units, each of which is used to control the flow of each corresponding material delivery process; The energy management system (38) comprises a data processing module (381) and a control signal output module (382), wherein the data processing module (381) is used to receive power supply and demand data, and the control signal output module (382) is connected to a plurality of the flow control units to output control signals respectively according to the power supply and demand data to control the working states of the plurality of the flow control units respectively.

9. The power grid peak load regulation system for coal and biomass co-combustion according to claim 1, characterized in that: The feeding device comprises a coal powder feeding unit (1) and a biomass feeding unit (2); The pulverized coal feeding unit (1) is used to store coal raw materials; The biomass feeding unit (2) is used to store biomass raw materials; The discharge end of the coal powder feeding unit (1) and the discharge end of the biomass feeding unit (2) are both connected to the feed end of the silo (5) to provide coal raw materials and biomass raw materials to the silo (5).

10. A power grid peak-shaving method based on the power grid peak-shaving system of coal and biomass co-combustion according to any one of claims 1 to 9, comprising the following steps: The coal raw material and the biomass raw material are transported into the silo (5) by the feeding device; The silo (5) mixes the coal raw material and the biomass raw material, and then transports the mixed materials through the feed pipe (11) into the boiler (12) for combustion, thereby generating high-temperature flue gas and high-temperature and high-pressure steam; The high-temperature and high-pressure steam is transported through a main steam pipeline (13) into the first steam turbine (14) for use, thereby generating steam exhaust gas; When the electricity consumption is at a low peak, the high-temperature flue gas generated by the boiler (12), the heat in the steam exhaust gas after use by the first steam turbine (14), and the excess electric energy are stored in the molten salt energy storage system and the compressed air energy storage system respectively; When electricity consumption is at its peak, the heat and energy stored in the molten salt energy storage system and the compressed air energy storage system are released to generate electricity and supplement the grid load.

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