A coal and biomass mixed combustion power grid peak regulation system and method

Abstract

The present invention belongs to the technical field of power grid peak regulation, and discloses a power grid peak regulation system and method for the co-combustion of coal and biomass. The power grid peak regulation system includes a feeding device, a silo, a boiler, a feeding pipe, a first steam turbine, a flue gas purification device, a molten salt energy storage system and a compressed air energy storage system. The present invention combines compressed air energy storage and molten salt energy storage technology to provide an efficient, economical and environmentally friendly power grid peak regulation system, and the power grid peak regulation system of the present invention can store excess electrical energy and thermal energy during low-peak electricity consumption periods, and release these energies during peak electricity consumption periods to meet electricity demand; and the power grid peak regulation system of the present invention can also realize the recovery and utilization of waste heat in flue gas and exhaust gas from steam turbines, increase power generation while reducing heat loss of the system, improve energy utilization efficiency, help balance the power grid load, reduce the pressure of peak load on the power grid, and improve the operation efficiency and reliability of the power grid.

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 shaving presents a significant technical challenge. With the rapid development of renewable energy, grid load fluctuations have become more severe and unpredictable, further complicating peak shaving. Traditional peak shaving methods often rely on adjusting fossil fuel usage, which not only reduces combustion efficiency but also suffers from low sensitivity. Therefore, to improve the sensitivity of grid peak shaving while reducing operating and maintenance costs and minimizing environmental impact, energy storage can be used to enhance the flexibility and efficiency of grid peak shaving.

[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 air storage units, 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 above-mentioned traditional compressed air energy storage, such as slow response speed and low peak-shaving capacity, and the need for a large space to build air storage units, the present invention provides a coal-biomass co-combustion power grid peak-shaving system and method. The present invention combines compressed air energy storage technology, molten salt energy storage technology, and energy recovery and utilization technology to provide a coal-biomass co-combustion power grid peak-shaving system. By using the coal-biomass co-combustion power grid peak-shaving system of the present invention to perform power grid peak-shaving, it is possible to not only improve fuel utilization, but also significantly improve the flexibility and efficiency of power grid peak-shaving, reduce operating and maintenance costs, and reduce negative impacts on the environment.

[0005] The coal and biomass mixed combustion power grid peak shaving system and method of the present invention is achieved through the following technical solutions:

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

[0007] The present invention takes into account the technical problems that traditional compressed air energy storage can handle large-scale long-term energy storage needs, but has low response speed and peak-shaving capacity. At the same time, a larger space is required 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 and utilization technology, aiming to ensure fuel utilization while improving the peak-shaving sensitivity of the power grid, thereby reducing operating and maintenance costs. The present invention provides a coal and biomass co-combustion power grid peak-shaving system that 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 low-peak electricity consumption, the grid peak-shaving system of the present invention stores the heat and excess electricity 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 peak 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 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 use 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, cooled flue gas and cooled steam exhaust gas. 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 periods of low electricity demand, 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 for the first time to absorb heat and heat up. At the same time, the exhaust steam from the steam turbine and the purified flue gas 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 a second time by the electric heater and then enters the high-temperature molten salt storage unit for storage. This allows the heat in the flue gas and steam, as well as some excess electricity, to be stored in the molten salt during periods of low electricity demand. 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 supply end of the third heat exchange unit is also connected to a water source. 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 unit to absorb heat and heat up 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. The compressor input is connected to the exhaust port of the second heat exchange unit and is also connected to an air source. The compressor output is connected to the input of the fourth heat exchange unit, which is in turn connected to the high-pressure gas storage unit. The output of the fourth heat exchange unit is connected to the input of the first steam turbine, which is in turn connected to the second steam turbine. During off-peak electricity consumption, a small amount of excess electricity is stored in the molten salt energy storage system, while the majority of excess electricity is stored in the compressed air energy storage system. After releasing heat and cooling in the second heat exchange unit, the gas mixes with air through a pipeline and enters the compressor. The gas temperature and pressure increase, and the heated and pressurized gas enters the fourth heat exchange unit to release heat and cool down. Simultaneously, water enters the fourth heat exchange unit, absorbing heat and heating it to become superheated steam. The heated superheated steam enters the input of the first steam turbine from the output of the fourth heat exchange unit. After releasing heat in the fourth heat exchange unit, the gas enters the high-pressure gas storage unit for storage. During peak electricity demand, the energy stored in the compressed air energy storage system is converted into electrical energy for 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 shaving system further comprises a first heat exchange unit, wherein the air inlet 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 use by the first steam turbine. The water inlet 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 peak power consumption, after water is input to the water inlet of the first heat exchange unit, the water enters the first heat exchange unit, absorbs heat from the flue gas purified by the flue gas purification device and the steam exhaust gas after use by the first steam turbine, and is then converted into superheated steam. The superheated steam enters the first steam turbine, providing 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. The flow regulation system includes a plurality of flow control units, each of which is 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. The data processing module is used to receive power supply and demand data. The control signal output module is connected to the plurality of flow control units to output control signals based on the power supply and demand data to control the operating status of the plurality of flow control units, thereby achieving intelligent peak-shaving of the power grid.

[0024] In some preferred embodiments of the present invention, the feeding device includes a pulverized coal feeding unit and a biomass feeding unit, wherein the pulverized coal feeding unit is used to store coal raw material, and the biomass feeding unit is used to store biomass raw material. The discharge ends of the pulverized coal feeding unit and the biomass feeding unit are both connected to the feed end of the silo to provide the coal raw material and the biomass raw material 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 pulverized coal 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 regulate 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 materials and biomass raw materials 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 flow rate of the primary air 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 provided 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 regulate 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 provided between the steam outlet of the first steam turbine and the input end of the second heat exchange unit, so as to regulate the amount of heat in the steam exhaust gas after use by the first steam turbine 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 the 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 of 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 particulate matter capture device. After initial 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 particulate matter capture device in a single pass, effectively removing large particles, sulfur dioxide, nitrogen oxides, carbon dioxide, and other solid particulate matter from the flue gas. While ensuring that flue gas emissions meet environmental standards, it also allows the integration of 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: transporting 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 electricity consumption is at a low peak, 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 electricity 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 is capable of 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, and 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 power demand. When power demand is low, the system can store excess heat and electricity in the molten salt; when power demand is high, the system can release the stored heat and electricity and convert it into electrical energy output, thereby achieving rapid peak regulation of the power grid.

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

[0050] The present invention removes harmful substances such as SO2, nitrogen oxides, particulate matter, etc. in the flue gas through the 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 intelligently controlling coal and biomass co-firing provided in one embodiment of the present invention; Figure 1The figures in the figure are marked as follows: 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 pipe; 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 figures 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 capabilities are relatively slow. Furthermore, it requires a larger space to construct the air storage units, resulting in increased equipment and land costs, as well as higher construction and maintenance costs. This invention combines compressed air energy storage with molten salt energy storage and energy recovery technologies, aiming to improve grid peak-shaving sensitivity while maintaining fuel efficiency, thereby reducing operating and maintenance costs.

[0055] Example 1

[0056] Combine Figure 1 As shown, this embodiment provides a power grid peak regulation system that burns coal and biomass together.

[0057] The coal and biomass mixed combustion power grid peak-shaving 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 pulverized coal feeding unit 1 and a biomass feeding unit 2, wherein the outlet of the pulverized coal feeding unit 1 and the outlet of the biomass feeding unit 2 are both connected to the silo 5, so that the pulverized coal feeding unit 1 provides the pulverized coal 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, the boiler 12 is provided with a burner 10 that is connected to the interior of the boiler 12. 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 via a main steam pipe 13 to receive high-temperature, high-pressure steam from the boiler 12. The air inlet of the flue gas purification device 15 is connected to the exhaust end of the boiler 12 via a 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 pulverized coal feeding unit 1 and the biomass fuel in the biomass feeding unit 2 enter the silo 5 and are evenly mixed. The mixed fuel in the silo 5 enters the feeding pipe 11, and the primary air enters the feeding pipe 11 and carries the mixed fuel into the burner 10. At the same time, 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 mixes with the fuel through the feeding pipe 11, helping the fuel to form an appropriate airflow for combustion. At the same time, the secondary air is sent into the boiler 12 through the secondary air inlet 9, 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 from the heat absorbed by the water in the boiler 12 enters the first steam turbine 14 through the main steam pipe 13, converting the thermal energy into mechanical energy, generating power to drive electricity generation.

[0062] On the basis of the above-mentioned embodiment, in order to realize the intelligent peak regulation of the power grid and 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 regulation 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. 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. This embodiment also includes a solar collector to collect solar radiation energy and convert it into thermal energy, or an electric heater to use 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 via 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 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 via 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 feed 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 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-shaving system further includes a first heat exchange unit 17, the air inlet end of the first heat exchange unit 17 being in communication with the exhaust end of the flue gas purification device 15, and the steam inlet of the first heat exchange unit 17 being in communication with 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 use by the first steam turbine 14. The water inlet end of the first heat exchange unit 17 is also in communication with a water source, and the steam inlet of the first heat exchange unit 17 is in communication with the steam outlet of the first steam turbine 14, so that water enters the first heat exchange unit 17, absorbs heat from the flue gas purified by the flue gas purification device 15 and the steam exhaust gas after use by the first steam turbine 14, and is then converted into superheated steam, which 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 steam channel. 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 perform 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 and are 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, transferring 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 periods of low electricity demand, the system can store heat from flue gas and steam, as well as excess electricity, in molten salt. The low-temperature molten salt in the low-temperature molten salt storage unit 18 flows through the molten salt delivery pipeline 22 into the second heat exchange unit 20, where it absorbs heat and heats up for the first time. Simultaneously, exhaust steam from the steam turbine and purified flue gas also flow through the pipeline into the second heat exchange unit 20, where they release heat and cool down. The molten salt, having been heated once, is then heated again by the electric heater 23 before being stored in the high-temperature molten salt storage unit 19. During peak electricity demand periods, the molten salt energy storage system releases the stored heat to generate electricity. The high-temperature molten salt in the high-temperature molten salt storage unit 19 flows into the third heat exchange unit 21, where it releases heat and cools down. Simultaneously, water also flows into the third heat exchange unit 21, where it absorbs heat and heats up to become superheated steam. The superheated steam is output from the second output port of the third heat exchange unit 21 and enters the input port of the first steam turbine 14. The molten salt, having released heat in the third heat exchange unit 21, flows through the first output port and enters the low-temperature molten salt storage unit 18 for storage.

[0068] During peak electricity consumption, the exhaust gas from the first steam turbine 14 and the flue gas purified by the flue gas purification device 15 enter the first heat exchange unit 17 to release heat. Simultaneously, water enters the first heat exchange unit 17, absorbing heat and converting it into superheated steam. The superheated steam is output through the first output port of the first heat exchange unit 17 and then enters the input port of the first steam turbine 14. The exhaust gas, which has released heat, is discharged through the second output port of the first heat exchange unit 17 and into the chimney.

[0069] In a preferred embodiment of the present invention, a fan is required to ensure that the fuel can be smoothly fed from the silo 5 into the burner 10 and fully mixed with the air within the burner 10. The end of the feed pipe 11 away from the burner 10 is connected to a first fan 39, which is used to provide primary air to the feed pipe 11. A second fan 40 is connected to the secondary air port 9 on the boiler 12 via a pipe and 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 inlet 9, and the secondary air inlet 9 is provided with a second fan 40. The second fan 40 is used to provide secondary air to the secondary air inlet 9, provide additional oxygen for the combustion of the fuel, and 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-shaving 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 configured to receive power supply and demand data. The control signal output module 382 is connected to the plurality of flow control units to output control signals based on the power supply and demand data to control the operating 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 pulverized coal feeding unit 1 and the feed end of the silo 5 . The first flow control unit 3 is used to regulate 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 regulate 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 materials and biomass raw materials 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 first 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 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 second fan 40 and the secondary air outlet 9 , and the fifth flow control unit 8 is used to regulate the size of 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 rate 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 provided 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 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 regulate 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 use by the first steam turbine 14 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 34 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 34 .

[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 gas storage unit 28, so as to control the flow rate of the high-pressure air after heat exchange entering the high-pressure gas 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 of high-pressure air entering the second steam turbine 29 through the fifteenth flow control unit 37.

[0089] Based on the above-mentioned implementation, this system can flexibly adjust the amount of coal and biomass used, as well as the primary and secondary air volumes, to achieve the desired results. The flue gas generated by the combustion of the mixed fuel in boiler 12 is then sent to flue gas purification device 15 for purification, removing harmful substances such as SO2, nitrogen oxides, and particulate matter from the flue gas. This prevents the flue gas from clogging pipelines during subsequent recycling, while also preventing the emission of toxic gases, contributing to environmental protection.

[0090] In order to realize intelligent control of power grid peak regulation, the energy management system 38 receives and processes the power supply and demand data, and when the power supply exceeds the 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 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 power grid peak shaving method using molten salt coupled with compressed air energy storage using a blend of coal and biomass, including the following steps:

[0092] Step 1: transport 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] In step 3, the high-temperature and high-pressure steam is transported through the main steam pipe 13 into the first steam turbine 14 for use to generate steam exhaust gas.

[0095] During the off-peak period of electricity consumption, 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] During peak electricity consumption periods, the heat in the high-temperature flue gas and exhaust gas from the steam 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] This invention utilizes molten salt and compressed air energy storage technologies, combined with intelligent peak-shaving technology. This technology uses a molten salt heat storage and release cycle to store and release energy based on grid peaks, achieving efficient energy migration and improving the intermittent and unstable nature of new power systems. This technology stores excess electricity and heat during low-peak periods and releases this energy to meet demand during peak periods, significantly enhancing the flexibility of grid peak-shaving. Furthermore, a heat exchanger recycles waste heat from flue gas and turbine exhaust gas, increasing power generation while reducing heat losses in the system, further improving energy 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 is efficient, economical and operational. 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, this system is more flexible in dealing with fluctuations in electricity demand, provides a more stable power supply, helps balance the load of the power grid, reduces the pressure of peak loads 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 a 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 taken into consideration, such as using renewable energy such as solar energy as a heat source to reduce dependence on fossil fuels. It has broad application prospects and huge development potential.

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

Claims

1. A coal and 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 regulation system includes: A feeding device, used for supplying coal raw materials and biomass raw materials; A silo (5) having a feed end connected to a discharge end of the feeding device for receiving coal raw materials and biomass raw materials from the feeding device and mixing the coal and biomass to form a mixed fuel; A boiler (12) is provided with a burner (10) in communication with the interior of the boiler (12); a feed end of the burner (10) is in communication with an output end of the silo (5) via a feed pipe (11), so that a mixed fuel enters the boiler (12) through the feed pipe (11) for combustion, thereby generating high-temperature flue gas, while 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 in communication with the steam outlet of the boiler (12) via a main steam pipe (13) 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) to receive and purify the high-temperature flue gas from the boiler (12); a molten salt energy storage system for receiving and storing heat from the flue gas purified by the flue gas purification device (15) and from the steam exhaust gas used by the first steam turbine (14); A compressed air energy storage system for receiving and storing 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 shaving system for coal and biomass co-firing 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 delivery pipeline (22) and an electric heater (23); The input end of the second heat exchange unit (20) is in communication with 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 in communication with the output end of the low-temperature molten salt storage unit (18) via 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 communicated with the input end of the first steam turbine (14).

3. The power grid peak shaving system for coal and biomass co-firing as claimed in 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 the 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 in communication with the exhaust end of the fourth heat exchange unit (27) to receive and store the gas after heat release from 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.

4. The power grid peak shaving system for coal and biomass co-firing according to claim 1, characterized in that: The power grid peak 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) and absorbs 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 is then 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 shaving system for coal and biomass co-firing 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 shaving system for coal and biomass co-firing 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 shaving system for coal and biomass co-firing according to claim 1, characterized in that: The boiler (12) is provided with a secondary air inlet (9), and the secondary air inlet (9) is provided with a second fan (40). The second fan (40) is used to provide secondary air to the secondary air inlet (9), provide additional oxygen for the combustion of the fuel, and promote the complete combustion of the fuel.

8. The power grid peak shaving system for coal and biomass co-firing 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). 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.

9. The power grid peak shaving system for coal and biomass co-firing according to claim 1, characterized in that: The feeding device comprises a pulverized coal 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 pulverized coal 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-firing 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) through 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 pipe (13) into the first steam turbine (14) for use, thereby generating steam exhaust gas; 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 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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