Compressed air energy storage system for medium-temperature hot water heat storage

Abstract

The invention discloses a compressed air energy storage system for medium-temperature hot water heat storage, and belongs to the technical field of energy storage, the compressed air energy storage system comprises a compressor subsystem, an expansion machine subsystem, a heat storage subsystem, a heat exchange subsystem, a gas storage subsystem and an auxiliary machine subsystem; the auxiliary machine subsystem controls the temperature of hot water in a hot water storage tank through a hot water temperature control model and controls the pressure of the hot water storage tank and the pressure of a cold water storage tank through a pressure control model, a heat storage medium in the hot water storage tank of the compressed air energy storage system is medium-temperature hot water under pressure, and the temperature of warm water in the hot water storage tank is controlled to be 170-185 DEG C; and the pressure of the medium-temperature hot water is 1.5-1.6 MPa. By accurately controlling the temperature and the pressure of the hot water storage tank, the efficiency of the power station is improved, the cost can be effectively reduced, the safety risk is also effectively reduced, the tail end cooler is linked with collaborative cooling of preheating, user heat supply and low-temperature power generation modes at the same time, and the energy consumption is reduced. And the efficiency of the system is further improved while the heat energy is effectively utilized.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to a compressed air energy storage system for storing heat in medium-temperature hot water. Background Art

[0002] Compressed air energy storage, as a long-term energy storage technology, has the advantages of large energy storage capacity, short construction period, long operating life, safety and environmental protection. It can cope with the rapid development of new energy such as wind power and photovoltaics, ensure the safe and stable operation of electricity, and help achieve the dual carbon goals.

[0003] There are many types of compressed air energy storage technologies, which are divided into supplementary combustion type and non-supplementary combustion type compressed air energy storage according to whether a heat source is required. Traditional supplementary combustion type compressed air energy storage systems are heavily dependent on fossil fuels such as natural gas, causing environmental pollution and not meeting the goal of energy structure transformation and development. For this reason, the current main technology is non-supplementary combustion type compressed air energy storage, which mainly includes low-pressure hot water heat storage low-temperature adiabatic compression technology, and high-temperature adiabatic compression technology combined with heat transfer oil and normal pressure hot water heat storage. The efficiency of compressed air energy storage is greatly affected by the temperature of the heat storage medium. The low-temperature adiabatic compression technology uses low-temperature and low-pressure hot water, and the heat storage temperature is about 120℃. The cost of low-temperature and low-pressure hot water is low, but the problem is that the efficiency is also low; the high-temperature adiabatic compression technology uses heat transfer oil and normal pressure hot water, and the heat storage temperature of the heat transfer oil is high, reaching 320-330℃, which greatly improves the efficiency of the power station, but the price of heat transfer oil is high and the safety risk is high. At the same time, the existing compressed air energy storage technology also has the problem of low precision in controlling the hot water temperature and pressure of the hot water storage tank, which will also affect the working efficiency of the power station, so it is necessary to balance multiple factors such as power station efficiency, safety, and investment cost. Therefore, a compressed air energy storage system with medium-temperature hot water heat storage is developed. It uses medium-temperature hot water to store heat and accurately controls the temperature and pressure of the hot water storage tank. It can effectively reduce costs while improving the efficiency of the power station and effectively reduce safety risks. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention discloses a compressed air energy storage system for storing medium-temperature hot water.

[0005] The present invention adopts the following technical solution: A compressed air energy storage system for medium-temperature hot water heat storage, the compressed air energy storage system comprising a compressor subsystem, an expander subsystem, a heat storage subsystem, a heat exchange subsystem, a gas storage subsystem and an auxiliary machine subsystem; The compressor subsystem is used to compress air to obtain compressed air; the air storage subsystem is used to store the compressed air; the heat storage subsystem and the heat exchange subsystem are used for heat exchange of the compressed air; the expander subsystem is used for the compressed air to expand and perform work through an air turbine; The heat exchange subsystem is divided into a compression side heat exchange subsystem and an expansion side heat exchange subsystem; the compression side heat exchange subsystem is used to heat and cool the compressed air; the expansion side heat exchange subsystem is used to heat the compressed air; the heat storage subsystem includes a hot water storage tank and a cold water storage tank; the heat exchange subsystem includes a heat exchanger; The auxiliary machine subsystem includes an external PLC controller, which includes a hot water temperature control model and a pressure control model. The algorithm adopted by the hot water temperature control model includes a PID algorithm or a BP neural network algorithm. The pressure control model adopts a PID algorithm. The hot water temperature control model is used to control the hot water temperature in the hot water storage tank. The pressure control model is used to control the pressure of the hot water storage tank and the cold water storage tank. The heat storage medium in the hot water storage tank is medium-temperature pressurized hot water. The temperature of the medium-temperature hot water is 170-185°C, and the pressure of the medium-temperature hot water is 1.5-1.6MPa.

[0006] Furthermore, the input of the hot water temperature control model is the deviation between the hot water temperature set value of the hot water storage tank and the actual value of the hot water temperature of the hot water storage tank, and the output of the hot water temperature control model is the frequency of the cold water variable frequency pump; the pressure control model uses the hot water temperature at the air side inlet of the heat exchanger and the compressor flow value as feedforward values ​​of the model, and the input of the pressure control model includes the deviation between the hot water tank pressure set value and the actual value of the hot water tank pressure and the deviation between the cold water tank pressure set value and the actual value of the hot water and cold water tank pressures, and the output of the pressure control model is the opening of the auxiliary subsystem pressure regulating valve.

[0007] Furthermore, the heat exchanger includes a cooling heat exchanger and a heating heat exchanger, and the compressor subsystem includes two or more compressors, which are connected in series in sequence. The compressed gas generated by the compressor passes through the cooling heat exchanger, the cooler and the gas-liquid separator in sequence, and then continues to enter the next compressor for compression. The compressor located at the front end of the series compressor is the first compressor, and the compressor located at the end of the series compressor is the terminal compressor. An air filter and a muffler are provided at the front end of the first compressor, and the cooler connected to the outlet of the terminal compressor is the terminal cooler. The compressed gas generated by the terminal compressor flows through the terminal cooler and the gas-liquid separator in sequence and then enters the gas storage reservoir. The first switch valve and the first regulating valve are provided in sequence on the pipeline connecting the gas-liquid separator to the gas storage reservoir.

[0008] Furthermore, a first air turbine, a second air turbine and a first generator are sequentially arranged behind the gas storage reservoir, a heating heat exchanger is provided between the gas storage reservoir and the first air turbine, a heating heat exchanger is provided between the first air turbine and the second air turbine, and a switch valve and a regulating valve are sequentially provided on the connecting pipe between the gas storage reservoir and the heating heat exchanger.

[0009] Furthermore, the air inlet end of the first air turbine is provided with a compressed air inlet pipe and a compressed air supply pipe, the air inlet pipe is provided with a regulating valve, the air supply pipe is provided with an air supply valve, and the air inlet pipe of the second air turbine is provided with a regulating valve.

[0010] Furthermore, the hot water storage tank and the cold water storage tank are connected by a pressurized pipe, and the auxiliary machine subsystem is provided on the pressurized pipe. The cold water in the cold water storage tank is transported to the cooling heat exchanger for heat exchange by a cold water pump, and the hot water generated after the heat exchange is transported to the hot water storage tank; the medium-temperature hot water in the hot water storage tank is transported to the heating heat exchanger for heat exchange by a hot water pump, and the cold water generated after the heat exchange is transported to the cold water storage tank.

[0011] Furthermore, the storage temperature of the cold water storage tank is 40-45°C, the cold water storage tank and the hot water storage tank are connected to the electric heating device through an electric heating pipeline, and the hot water storage tank and the cold water storage tank are provided with an air release valve and a safety valve.

[0012] Furthermore, the hot water generated by the heat exchange in the terminal cooler is used to preheat the air to be compressed. The air to be compressed is air processed by an air filter and a muffler. The air to be compressed enters the first compressor after being preheated.

[0013] Furthermore, the hot water generated by the heat exchange in the terminal cooler enters the user heating hot water storage tank through a pipe, the hot water in the user heating hot water storage tank is used for user heating, and the cold water after the heating heat exchange flows into the user heating cold water storage tank, and the cold water in the user heating cold water storage tank flows back to the terminal cooler through a pipe.

[0014] Furthermore, the hot water generated by the terminal cooler is used for low-temperature power generation and coordinated cooling, and the coordinated cooling includes: the hot water generated by the heat exchange of the cooler is used for steam power generation, the water temperature after power generation is detected by a temperature control detector, the power generation power of the participating generator sets is adjusted, and the water temperature after power generation is controlled to maintain within an appropriate temperature range. The appropriate temperature range is the required water temperature for water used by the terminal cooler.

[0015] Beneficial effects: (1) The compressed air energy storage system provided by the present invention uses pressurized high-temperature hot water to store the heat after compression by the compressor, and uses it to heat the air required by the expander. On the one hand, the hot water is pressurized to prevent the hot water from boiling and eliminate safety risks. On the other hand, the temperature range of the hot water is increased from 120°C to 170-185°C, which increases the heat storage temperature of the heat storage medium and improves the work capacity of the expander.

[0016] (2) As the temperature rises, the pressure required to prevent the liquid water from boiling also increases. The increase in pressure will inevitably put forward higher requirements on the material and thickness of the water storage tank, which will increase the investment cost. The present invention takes into account both investment and efficiency. Compared with the normal temperature and pressure equipment, the hot water temperature is increased to 170-185°C and the pressure reaches 1.5-1.6MPa without increasing the investment cost. The medium-pressure hot water heat storage compressed air energy storage system provided by the present invention has high safety and significantly improved system operation efficiency compared with the normal temperature and pressure heat storage system. The equipment investment cost is much lower than the existing high-temperature and high-pressure equipment investment, and the system operation is also safer and more stable.

[0017] (3) The present invention controls the temperature and pressure of the medium-temperature hot water in the hot water storage tank through the temperature control module and the pressure control module of the auxiliary system. The temperature control module and the pressure control module can well control the temperature and pressure within the medium temperature range. The hot water temperature control model inputs the deviation between the hot water temperature setting value of the hot water storage tank and the actual value of the hot water temperature of the hot water storage tank. The pressure control model uses the hot water temperature at the air side inlet of the heat exchanger and the compressor flow value as the feedforward value of the model. At the same time, the deviation between the hot water tank pressure setting value and the actual value of the hot water tank pressure and the deviation between the cold water tank pressure setting value and the actual value of the hot water and cold water tank pressure are used as inputs. The two control modules realize accurate control of temperature and pressure, and accurately control the medium-temperature hot water temperature in the hot water storage tank of the power station to 170-185℃ and the medium-temperature hot water pressure to 1.5-1.6MPa. Within this temperature and pressure range, the compressed air energy storage power station can be ensured to operate efficiently and safely.

[0018] (4) The present invention reuses the heat energy of the terminal cooler, preheats the air after being processed by the air filter and the muffler, fully utilizes the heat energy of the terminal cooler and effectively improves the compression efficiency of the compressor; the hot water generated by the heat exchange of the terminal cooler enters the user heating hot water storage tank through a pipeline, and the hot water in the user heating hot water storage tank is used for user heating, which fully utilizes the heat energy and improves the working efficiency of the terminal cooler; The hot water generated by the terminal cooler is cooled down through the cooling tower and power supply. In particular, the water temperature after power generation is detected by the temperature control detector, the power generation power of the participating generator sets is adjusted, and the water temperature after power generation is maintained within an appropriate temperature range. Automatic power supply control is achieved according to the water temperature demand of the cooler, effectively improving the power supply efficiency of the power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is an overall schematic diagram of a compressed air energy storage system for medium-temperature hot water heat storage of the present invention; Figure 2 This is a schematic diagram of the structure of a compressed air energy storage system for medium-temperature hot water heat storage in the present invention. Figure 1 ; Figure 3 It is a schematic flow chart of an operation method of a compressed air energy storage system for medium-temperature hot water heat storage according to the present invention; FIG4 (a) is a schematic diagram of a hot water temperature control model of a hot water storage tank of a compressed air energy storage system for medium-temperature hot water heat storage according to the present invention; FIG4 (b) is a schematic diagram of a pressure control model of a hot water storage tank and a cold water storage tank of a compressed air energy storage system for medium-temperature hot water heat storage according to the present invention; Figure 5 This is a schematic diagram of the structure of a compressed air energy storage system for medium-temperature hot water heat storage in the present invention. Figure 2 ; Figure 6 This is a schematic diagram of the structure of a compressed air energy storage system for medium-temperature hot water heat storage in the present invention. Figure 3 ; Figure 7 This is structural schematic diagram 4 of a compressed air energy storage system for storing medium-temperature hot water according to the present invention. DETAILED DESCRIPTION

[0021] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0022] It should be clear that the described 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 creative work are within the scope of protection of the present invention.

[0023] A compressed air energy storage system for medium-temperature hot water heat storage, the compressed air energy storage system comprising a compressor subsystem, an expander subsystem, a heat storage subsystem, a heat exchange subsystem, a gas storage subsystem and an auxiliary machine subsystem; The compressor subsystem is used to compress air to obtain compressed air; the air storage subsystem is used to store the compressed air; the heat storage subsystem and the heat exchange subsystem are used for heat exchange of the compressed air; the expander subsystem is used for the compressed air to expand and perform work through an air turbine; The heat exchange subsystem is divided into a compression side heat exchange subsystem and an expansion side heat exchange subsystem; the compression side heat exchange subsystem is used to heat and cool the compressed air; the expansion side heat exchange subsystem is used to heat the compressed air; The compression subsystem includes a compressor, an air filter, a muffler and a motor; the expander subsystem includes an air turbine; the heat storage subsystem includes a hot water storage tank and a cold water storage tank; the heat exchange subsystem includes a heat exchanger, a cooler and a gas-liquid separator; the gas storage subsystem includes a gas storage; The auxiliary machine subsystem includes an external PLC controller, which includes a hot water temperature control model and a pressure control model. The algorithm adopted by the hot water temperature control model includes a PID algorithm or a BP neural network algorithm. The pressure control model adopts a PID algorithm. The hot water temperature control model is used to control the hot water temperature in the hot water storage tank. The pressure control model is used to control the pressure of the hot water storage tank and the cold water storage tank. The heat storage medium in the hot water storage tank is medium-temperature pressurized hot water. The temperature of the medium-temperature hot water is 170-185°C, and the pressure of the medium-temperature hot water is 1.5-1.6MPa.

[0024] Furthermore, the input of the hot water temperature control model is the deviation between the hot water temperature setting value of the hot water storage tank and the actual value of the hot water temperature of the hot water storage tank, and the output of the hot water temperature control model is the frequency of the cold water variable frequency pump; the pressure control model uses the hot water temperature at the air side inlet of the heat exchanger and the compressor flow value as the feedforward value of the model, as shown in Figure 4 (a), and the input of the pressure control model includes the deviation between the hot water tank pressure setting value and the actual value of the hot water tank pressure and the deviation between the cold water tank pressure setting value and the actual value of the hot water and cold water tank pressures, and the output of the pressure control model is the opening of the auxiliary subsystem pressure regulating valve, as shown in Figure 4 (b).

[0025] Furthermore, if Figure 2 , 5As shown in Figures 6 and 7, the heat exchanger includes a cooling heat exchanger and a heating heat exchanger, and the compressor subsystem includes two or more compressors 2, 3, and 4. The compressors 2, 3, and 4 are connected in series in sequence. The compressed gas generated by the compressor passes through the cooling heat exchanger (8, 11), the cooler 9, 12, and the gas-liquid separator 10, 13 in sequence, and then continues to enter the next compressor for compression. The compressor located at the front end of the series compressor is the first compressor 2, and the compressor located at the end of the series compressor is the terminal compressor 4. The front end of the first compressor 2 is provided with an air filter and a muffler 1, and the cooler connected to the outlet of the terminal compressor is the terminal cooler. The compressed gas generated by the terminal compressor 4 flows through the terminal cooler 14 and the gas-liquid separator 15 in sequence and then enters the gas storage reservoir. The pipeline connecting the gas-liquid separator to the gas storage reservoir is provided with a first switch valve 33 and a first regulating valve 34 in sequence.

[0026] Furthermore, a first air turbine 18, a second air turbine 20 and a first generator 21 are sequentially arranged behind the gas storage reservoir, the heating heat exchanger includes a first heating heat exchanger 17 and a second heating heat exchanger 19, a first heating heat exchanger 17 is arranged between the gas storage reservoir and the first air turbine, a second heating heat exchanger 19 is arranged between the first air turbine 18 and the second air turbine 20, and a second switch valve 35 and a second regulating valve 36 are sequentially arranged on the connecting pipeline between the gas storage reservoir 16 and the first heating heat exchanger 17.

[0027] Furthermore, the air intake end of the first air turbine 18 is provided with a compressed air intake pipe and a compressed air supply pipe, the air intake pipe is provided with a regulating valve (third regulating valve) 37, the supply pipe is provided with an air supply valve 38, and the air intake pipe of the second air turbine 20 is provided with a regulating valve (fourth regulating valve) 39.

[0028] Furthermore, the heat exchange subsystem includes hot water storage tanks 22, 23 and cold water storage tanks 24, 25, which are connected by pressurized pipes. The auxiliary machine subsystem is provided on the pressurized pipes. The cold water in the cold water storage tanks is transported to the cooling heat exchanger for heat exchange through cold water pumps 31, 32, and the hot water generated after the heat exchange is transported to the hot water storage tanks; the medium-temperature hot water in the hot water storage tanks is transported to the heating heat exchanger for heat exchange through hot water pumps 29, 30, and the cold water generated after the heat exchange is transported to the cold water storage tanks 24, 25.

[0029] Furthermore, the storage temperature of the cold water storage tanks 24 and 25 is 40-45°C, and the storage temperature of the hot water storage tanks 22 and 23 is 170-185°C. The cold water storage tank and the hot water storage tank are connected to the electric heating device through electric heating pipes, and the hot water storage tank and the cold water storage tank are provided with air release valves and safety valves.

[0030] Furthermore, if Figure 5 As shown, the coolers 9 and 12 are cooled by a cooling tower 28, and the hot water generated by the heat exchange of the terminal cooler 14 is used to preheat the air to be compressed. The air to be compressed is the air processed by the air filter and the muffler 1. The air to be compressed enters the first compressor 2 after being preheated.

[0031] Furthermore, if Figure 6 As shown, the hot water generated by the heat exchange in the terminal cooler 14 enters the user heating hot water storage tank (third hot water storage tank) 41 through a pipe, and the hot water in the user heating hot water storage tank is used to heat the user 42. The cold water after the heating heat exchange flows into the user heating cold water storage tank (third cold water storage tank) 43, and the cold water in the user heating cold water storage tank flows back to the terminal cooler 14 through a pipe.

[0032] Furthermore, if Figure 7 As shown, the hot water generated by the terminal cooler 14 is used for low-temperature power generation and coordinated cooling, and the coordinated cooling includes: the hot water generated by heat exchange in the cooler 14 is used for steam power generation, the water temperature after power generation is detected by a temperature control detector, the power generation power of the participating generator sets is adjusted, and the water temperature after power generation is controlled to maintain within a suitable temperature range, which is the required water temperature for the terminal cooler.

[0033] like Figure 1 As shown, a compressed air energy storage system for medium-pressure hot water heat storage includes a compressor subsystem, an expander subsystem, a heat storage subsystem, a heat exchange subsystem, a gas storage subsystem, and an auxiliary subsystem. The heat exchange subsystem is divided into a compression side heat exchange subsystem and an expansion side heat exchange subsystem.

[0034] The compressor subsystem is connected to the compression side heat exchange subsystem, the compression side heat exchange subsystem is connected to the gas storage subsystem, and a switch valve and a regulating valve are provided between the compression side heat exchange subsystem and the gas storage subsystem.

[0035] The heat exchange subsystem is connected to the heat storage subsystem, and a water pump or a regulating valve is provided between the heat exchange subsystem and the heat storage subsystem.

[0036] The gas storage subsystem is connected to the expansion side heat exchange subsystem, and a switch valve and a regulating valve are provided between the gas storage subsystem and the expansion side heat exchange subsystem. The expansion side heat exchange subsystem is connected to the expander subsystem, and a regulating valve and an air supply valve are provided between the expansion side heat exchange subsystem and the expander subsystem.

[0037] like Figure 2 As shown, Figure 2 for Figure 1 Detailed compressed air energy storage system structure diagram, Figure 2Take three-stage compression and two-stage expansion as an example.

[0038] The compression subsystem includes a first compressor 2, a first motor 5, a second compressor 3, a second motor 6, a third compressor 4, a third motor 7, an air filter and a muffler 1. The compressor is a centrifugal or axial compressor.

[0039] The expander subsystem includes a first air turbine 18 and a second air turbine 19, and the air turbines adopt a secondary reheating method.

[0040] The heat storage subsystem includes a first hot water storage tank 22, a second hot water storage tank 23, a first cold water storage tank 24, and a second cold water storage tank 25. The heat storage medium used in the storage tank is pressurized water. The hot water storage tank is mainly used to store hot water after heat exchange with the compressor, and the storage temperature is about 170-185°C; the cold water storage tank is mainly used to store cold water after heat exchange with the air turbine, and the storage temperature is about 40-45°C. The hot water storage tank and the cold water storage tank are both provided with an electric heating device 27 to maintain the required temperature of the tank body. The hot water storage tank and the cold water storage tank are provided with a vent valve and a safety valve, and are also provided with an auxiliary machine subsystem 26 and a pressurized connection channel to facilitate pressurization of hot water to prevent water from boiling.

[0041] The compression side heat exchange subsystem mainly includes a first cooling heat exchanger 8, a first cooler 9, a first gas-liquid separator 10, a second cooling heat exchanger 11, a second cooler 12, a second gas-liquid separator 13, a third cooler (terminal cooler) 14, and a third gas-liquid separator 15. The heat exchanger is a shell and tube heat exchanger or a hairpin heat exchanger.

[0042] The expansion side heat exchange subsystem mainly includes a third heat exchanger 17 and a fourth heat exchanger 19, and the heat exchangers are shell and tube heat exchangers or hairpin heat exchangers.

[0043] The gas storage subsystem may be made of salt caverns, artificial chambers or pipeline steel.

[0044] The auxiliary machine subsystem is a circulating cooling water system. The circulating cooling water system is mainly used to re-cool the air in the first cooler 9, the second cooler 12, and the third cooler (terminal cooler) 14. The cold water used for cooling mainly comes from the cooling tower 28. The hot water after heat exchange enters the cooling tower 28 for cooling.

[0045] like Figure 3As shown, a method for operating a compressed air energy storage system for medium-pressure hot water heat storage is provided, wherein the operating method is divided into a compression process and an expansion process. The heat storage medium uses medium-temperature pressurized hot water, the temperature of the medium-temperature hot water is 170-185°C, and the pressure is 1.5-1.6MPa; through the actual operation measurement of the compressed air energy storage system with medium-pressure hot water heat storage of the present invention, when the temperature of the medium-temperature hot water is 170-185°C and the pressure of the medium-temperature hot water is 1.5-1.6MPa, the operation efficiency of the energy storage system is improved by 5-8% compared with the compressed air energy storage system with normal temperature and pressure hot water heat storage, and the system operation is also more stable, more efficient and safer. Through experimental testing, when the temperature of the medium-temperature hot water of the present invention is 180°C and the pressure of the medium-temperature hot water is 1.55MPa, the stability of the system reaches the best; and when the medium-temperature hot water of the system is controlled at 170-185°C and the pressure is 1.5-1.6MPa, the equipment cost of the system is close to the cost of normal temperature and pressure equipment. Compared with the equipment and heat storage medium required for high temperature and high pressure, it can effectively reduce the cost and the operation is safer.

[0046] The compression process is as follows: ambient air enters the first compressor 2 through the filter and the silencer 1, and the first motor 5 of the first compressor 2 is driven to rotate by utilizing off-peak electricity, abandoned wind and abandoned photovoltaic power. The high-temperature compressed air compressed by the first compressor 2 enters the air side of the first cooling heat exchanger 8, and the air after heat exchange enters the first cooler 9 for further cooling. The cooled air enters the first gas-liquid separator 10, and the dehydrated air enters the second compressor 3 to further increase the air pressure. The compressed air enters the air side of the second cooling heat exchanger 11, the second cooler 12, and the second gas-liquid separator 13 in sequence, and enters the third compressor 4 to continue to increase the pressure. The compressed air passes through the third cooler (terminal cooler) 14 and the third gas-liquid separator 15, and is stored in the gas storage reservoir 16 after passing through the first switch valve 33 and the first regulating valve 34. At this point, the gas storage process is completed.

[0047] The cold water in the first cold water storage tank 24 enters the water side of the first cooling heat exchanger 8 through the first cold water pump 31, and the cold water in the second cold water storage tank 25 enters the water side of the second cooling heat exchanger 11 through the second cold water pump 32. The cold water pump here can also be replaced by a regulating valve. After the cold water entering the water side exchanges heat with the high-temperature air entering the air side of the first cooling heat exchanger 8 and the air side of the second cooling heat exchanger 11, the cold water flowing through the first cooling heat exchanger 8 obtains hot water after heat exchange and is transported to the first hot water storage tank 22 through a hot water pipe. The cold water flowing through the second cooling heat exchanger 11 obtains hot water after heat exchange and is transported to the second hot water storage tank 23 through a hot water pipe. The cold water in the cooling tower 28 is transported to the first cooler 9, the second cooler 12, and the third cooler (terminal cooler) 14 through a cold water pipe, and the incoming air is further cooled. The cold water after heat exchange is converted into hot water and transported to the cooling tower 28 through a hot water pipe. The hot water is cooled by the cooling tower to complete the circulating water cooling. At this point, the heat exchange and heat storage process is completed.

[0048] The expansion process: the compressed air in the air storage reservoir 16 enters the air side of the third heat exchanger 17 after passing through the second switch valve 35 and the second regulating valve 36, is converted into high-temperature compressed air after exchanging heat, and enters the first air turbine 18 to do work after passing through the third regulating valve 37. When the amount of air is insufficient, the air replenishing valve 38 is opened to replenish air to the first air turbine 18. The air temperature drops after doing work, and enters the air side of the fourth heat exchanger 19 to exchange heat with hot water, so that the air temperature is increased. After passing through the fourth regulating valve 39, it enters the second air turbine 20 to continue doing work, driving the generator 21 to generate electricity, and the potential energy is converted into electrical energy. At this point, the deflation process is completed. The setting of the air replenishing valve makes the expansion work process more stable, which helps to improve the operating efficiency of the compressed air energy storage system.

[0049] The hot water in the first hot water storage tank 22 enters the water side of the fourth heat exchanger 19 through the first hot water pump 29, and the hot water in the second hot water storage tank 23 enters the water side of the third heat exchanger 17 through the second hot water pump 30. The hot water entering the water side exchanges heat with the low-temperature air entering the air side of the corresponding heat exchanger. The exchanged hot water is converted into cold water and transported to the first cold water storage tank 24 and the second cold water storage tank 25 through the cold water delivery pipeline. At this point, the heat exchange and heat recovery process is completed.

[0050] As shown in FIG4 , the control structure of the temperature and pressure in the compressed air energy storage system of medium-pressure hot water heat storage is mainly used to control the power station to automatically control the hot water temperature in the storage tank to 170-185°C and the pressure to 1.5-1.6MPa. The control structure includes an external PLC controller, which includes a hot water temperature control model and a pressure control model. As shown in FIG4 (a) and FIG4 (b), the hot water temperature control model adopts a PID controller or a BP neural network algorithm. The input of the model is the deviation between the set value of the hot water temperature of the hot water storage tank and the actual value of the hot water temperature of the hot water storage tank. The output is the frequency of the cold water variable frequency pump. The cold water volume at the water side inlet of the heat exchanger is adjusted by the frequency of the variable frequency pump, thereby controlling the hot water temperature value at the water side outlet of the heat exchanger. In the PID control process, the hot water temperature at the air side inlet of the heat exchanger and the compressor flow value are used as the feedforward values ​​of the model. As shown in Figure 4 (b), the pressure control model is a PID controller, the input of which is the deviation between the hot water (cold water) tank pressure set value and the hot water (cold water) tank pressure actual value, and the output is the opening of the pressure regulating valve of the auxiliary subsystem, thereby adjusting the hot water (cold water) tank pressure value.

[0051] like Figure 5 As shown, the hot water exchanged by the third cooler 14 is transported to the first preheater 40 through a pipeline for preheating the air before compression, and heating the air before entering the first compressor 2. The preheated cold water is used for greening or fire fighting. The temperature of the inlet air has a great influence on the efficiency of the compressor. The closer it is to the design working condition of the compressor, the higher its efficiency. A temperature control device is provided at the outlet of the preheater 40, and a control valve is provided on the hot water pipeline transported to the first preheater 40. By setting the set temperature of the temperature control device at the outlet of the preheater 40, the preheating system automatically adjusts the opening and closing degree of the control valve on the hot water pipeline according to the difference between the real-time temperature and the set temperature, and adjusts the preheating effect until the temperature at the outlet of the preheater 40 reaches the set value. By setting the preheater temperature control device, the air can be preheated to the design temperature regardless of summer or winter working conditions, effectively improving the system efficiency, recycling the heat, and avoiding waste of resources.

[0052] like Figure 6As shown, the hot water exchanged by the third cooler 14 is used in the heating system, and the heating system includes a third hot water storage tank 41, a third cold water storage tank 43, and a heating user 42. The water side outlet of the third cooler 14 is connected to the third hot water storage tank 41, the third hot water storage tank is connected to the water inlet of the heating user 42, the water outlet of the heating user 42 is connected to the third cold water storage tank 43, and the third cold water storage tank 43 is connected to the water side inlet of the third cooler 14. After the high-temperature air compressed by the third compressor 4 exchanges heat with the third cooler (terminal cooler) 14, the heat is recovered, and the exchanged hot water is sent to the third hot water storage tank 41 for supplying the heating user 42 to provide heat to the user, and the cold water collected for heating enters the third cold water storage tank 43. The cold water in the cold water storage tank 43 is used to cool the air of the third cooler 14, so as to realize the recovery and utilization of the heat after the third compressor 4 and avoid waste of resources.

[0053] like Figure 7 As shown, the hot water exchanged by the third cooler 14 is used in the ORC low-temperature power generation system to recover the compression heat of the third compressor 4 for power generation, improve the energy utilization rate of the system, and improve the system conversion efficiency. The ORC low-temperature power generation system includes a third air turbine 46, a second preheater 45, an evaporator 44, a condenser 47, and a working fluid pump 48. The water side outlet of the third cooler 14 is respectively connected to the water side of the second preheater 45 and the water side inlet of the evaporator 44, and the water side inlet of the third cooler 14 is respectively connected to the water side of the second preheater 45 and the water side outlet of the evaporator 44, forming a circulation of hot water and cold water, realizing the recovery of the compression heat after the third compressor 4. The third air turbine 46 is connected to the condenser 47, the condenser 47 is connected to the working fluid pump 48, the working fluid pump 48 is connected to the second preheater 45, the second preheater 45 is connected to the evaporator 44, and the evaporator 44 is connected to the third air turbine 46, forming a working fluid circulation of the ORC power generation system. The water side inlet of the condenser 47 is connected to the pipeline after cooling of the cooling tower 28, and the water side outlet of the condenser 47 is connected to the pipeline before cooling of the cooling tower 28. The gaseous working medium entering the condenser 47 is converted into a liquid working medium through the cooling tower. The hot water at the outlet of the third cooler 14 passes through the second preheater 45 to preheat the organic working medium. After the preheated organic working medium enters the evaporator 44, the liquid working medium is boiled by the outlet hot water and converted into a gaseous working medium, which drives the third turbine 46 to do work and drives the second generator 49 to generate electricity. The gaseous working medium after work enters the condenser 47, and the water is cooled to liquid by the circulating cooling water. After that, it is pressurized by the working medium pump and then passes through the second preheater 45 again to enter the thermodynamic cycle.

[0054] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A compressed air energy storage system for medium-temperature hot water heat storage, characterized in that: The compressed air energy storage system includes a compressor subsystem, an expander subsystem, a heat storage subsystem, a heat exchange subsystem, a gas storage subsystem and an auxiliary machine subsystem; The compressor subsystem is used to compress air to obtain compressed air; The gas storage subsystem is used to store the compressed air; The heat storage subsystem and the heat exchange subsystem are used for heat exchange of the compressed air; the expander subsystem is used for the compressed air to expand and perform work through an air turbine; The heat exchange subsystem is divided into a compression side heat exchange subsystem and an expansion side heat exchange subsystem; the compression side heat exchange subsystem is used to heat and cool the compressed air; the expansion side heat exchange subsystem is used to heat the compressed air; The compression subsystem includes a compressor, an air filter, a muffler and a motor; the expander subsystem includes an air turbine; the heat storage subsystem includes a hot water storage tank and a cold water storage tank; the heat exchange subsystem includes a heat exchanger, a cooler and a gas-liquid separator; the gas storage subsystem includes a gas storage; The auxiliary machine subsystem includes an external PLC controller, which includes a hot water temperature control model and a pressure control model. The algorithm adopted by the hot water temperature control model includes a PID algorithm or a BP neural network algorithm. The pressure control model adopts a PID algorithm. The hot water temperature control model is used to control the temperature of the medium-temperature hot water in the hot water storage tank. The pressure control model is used to control the pressure of the hot water storage tank and the cold water storage tank. The heat storage medium in the hot water storage tank is pressurized medium-temperature hot water. The temperature of the medium-temperature hot water is 170-185°C, and the pressure of the medium-temperature hot water is 1.5-1.6MPa.

2. According to claim 1, a compressed air energy storage system for medium-temperature hot water heat storage is characterized in that: The input of the hot water temperature control model is the deviation between the hot water temperature setting value of the hot water storage tank and the actual value of the hot water temperature of the hot water storage tank, and the output of the hot water temperature control model is the frequency of the cold water variable frequency pump; the pressure control model uses the hot water temperature on the air side inlet of the heat exchanger and the compressor flow value as the feedforward values ​​of the model, and the input of the pressure control model includes the deviation between the hot water tank pressure setting value and the actual value of the hot water tank pressure and the deviation between the cold water tank pressure setting value and the actual value of the hot water and cold water tank pressures, and the output of the pressure control model is the opening of the auxiliary subsystem pressure regulating valve.

3. According to claim 2, a compressed air energy storage system for medium-temperature hot water heat storage is characterized in that: The heat exchanger includes a cooling heat exchanger and a heating heat exchanger, and the compressor subsystem includes two or more compressors, which are connected in series in sequence. The compressed gas generated by the compressor passes through the cooling heat exchanger, the cooler and the gas-liquid separator in sequence, and then continues to enter the next compressor for compression. The compressor located at the front end of the series compressor is the first compressor, and the compressor located at the end of the series compressor is the terminal compressor. An air filter and a muffler are provided at the front end of the first compressor, and the cooler connected to the outlet of the terminal compressor is the terminal cooler. The compressed gas generated by the terminal compressor flows through the terminal cooler in sequence and then enters the gas storage reservoir.

4. A compressed air energy storage system for medium-temperature hot water heat storage according to claim 3, characterized in that: A first air turbine, a second air turbine and a first generator are sequentially arranged behind the gas storage reservoir; the heating heat exchanger includes a first heating heat exchanger and a second heating heat exchanger; a first heating heat exchanger is arranged between the gas storage reservoir and the first air turbine, and a second heating heat exchanger is arranged between the first air turbine and the second air turbine.

5. A compressed air energy storage system for medium-temperature hot water heat storage according to claim 4, characterized in that: The air inlet end of the first air turbine is provided with a compressed air inlet pipe and a compressed air supply pipe.

6. A compressed air energy storage system for medium-temperature hot water heat storage according to claim 5, characterized in that: The hot water storage tank and the cold water storage tank are connected by a pressurized pipe, and the auxiliary machine subsystem is arranged on the pressurized pipe. The cold water in the cold water storage tank is transported to the cooling heat exchanger for heat exchange by a cold water pump, and the hot water generated after the heat exchange is transported to the hot water storage tank; the medium-temperature hot water in the hot water storage tank is transported to the heating heat exchanger for heat exchange by a hot water pump, and the cold water generated after the heat exchange is transported to the cold water storage tank.

7. A compressed air energy storage system for medium-temperature hot water heat storage according to claim 6, characterized in that: The storage temperature of the cold water storage tank is 40-45° C., and the cold water storage tank and the hot water storage tank are connected to the electric heating device through an electric heating pipeline.

8. A compressed air energy storage system for medium-temperature hot water heat storage according to claim 7, characterized in that: The hot water generated by the heat exchange in the terminal cooler is used to preheat the air to be compressed. The air to be compressed is the air processed by the air filter and the muffler. The air to be compressed enters the first compressor after being preheated.

9. A compressed air energy storage system for medium-temperature hot water heat storage according to claim 7, characterized in that: The hot water generated by heat exchange in the terminal cooler enters the user heating hot water storage tank through a pipe. The hot water in the user heating hot water storage tank is used for user heating. The cold water after heat exchange for heating flows into the user heating cold water storage tank. The cold water in the user heating cold water storage tank flows back to the terminal cooler through a pipe.

10. A compressed air energy storage system for medium-temperature hot water heat storage according to claim 7, characterized in that: The hot water generated by the terminal cooler is used for low-temperature power generation and coordinated cooling. The coordinated cooling includes: the hot water generated by the heat exchange of the cooler is used for steam power generation, the water temperature after power generation is detected by a temperature control detector, the power generation power of the participating generator sets is adjusted, and the water temperature after power generation is controlled to maintain it within an appropriate temperature range. The appropriate temperature range is the required water temperature for the terminal cooler.

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