Liquid air energy storage power generation system

Abstract

The utility model discloses a liquid air energy storage power generation system which comprises a liquid air storage tank, an evaporator, a heater, an expansion turbine and a controller, the evaporator, the heater, the expansion turbine and the controller are sequentially arranged behind the liquid air storage tank, and the expansion turbine is connected with a power generator through a coupler. A cold storage tank and a frequency conversion fan are arranged on a heat exchange pipeline of the evaporator; a variable-frequency low-temperature pump is arranged on the pipeline between the liquid air storage tank and the evaporator; and the input ends of the variable-frequency low-temperature pump and the variable-frequency fan are respectively connected with the output end of the controller. According to the utility model, the outlet pressure of the heater is selected as the main gas pressure, the fluctuation of the main gas pressure is reduced, and the control valve and the temperature, pressure and flow measuring points are reasonably arranged, so that the power generation system has the potential of automatic operation, the reaction speed of the power generation system is accelerated, feedforward control is added, and the automatic operation of the power generation system is realized.

Description

Technical Field

[0001] This utility model relates to the field of liquid air energy storage technology, and more specifically to a liquid air energy storage power generation system. Background Technology

[0002] Against the backdrop of a "dual carbon" environment, my country's installed capacity of new energy sources, primarily photovoltaic and wind power, has surpassed that of thermal power. The intermittent and unstable nature of new energy sources also increases the pressure on large-scale grid connection and safe, stable operation, significantly limiting the large-scale application of renewable energy. To achieve widespread utilization of renewable energy, address its transient and unstable nature, and resolve the mismatch between energy supply and demand, energy storage technology plays a crucial role. Large-scale energy storage technology is an important strategic area for technological innovation worldwide and a major direction for achieving technological leadership.

[0003] Among various energy storage technologies, pumped hydro storage, large-capacity battery energy storage, and compressed air energy storage are the main ones that can be applied on a large scale. Pumped hydro storage depends on specific terrain, while compressed air energy storage requires underground salt caverns or gas storage caverns, limiting its applicable scenarios. Large-capacity battery energy storage deployment suffers from high costs, short cycle life, safety hazards, and environmental recycling challenges. Liquid air energy storage, as one of the compressed air energy storage technology routes, is a new type of large-scale grid energy storage technology with outstanding advantages such as high energy density, no geographical restrictions on site selection, high safety, and long life. It can be widely used in renewable energy consumption, grid peak shaving and frequency regulation, black start, distributed energy, and integrated energy services. The density of liquid air is much greater than that of compressed air, and its energy density (power generation per unit volume) is 15-20 times that of compressed air energy storage. It does not require special geological conditions (salt caverns, artificial chambers, abandoned mines) or a large number of high-pressure containers, and the system has no safety issues. Based on its significant advantages, liquid air energy storage is expected to become one of the most promising new energy storage technologies.

[0004] Liquid air energy storage consists of a liquefaction system and a power generation system. The liquefaction system operates during the energy storage phase, while the power generation system operates during the energy release phase. The power generation system needs to accept real-time adjustments to its output from the power grid. Liquid air energy storage power generation systems have many devices with strong coupling between them, making system operation difficult. Relying on manual responses to power grid dispatch is labor-intensive and carries the risk of errors. Furthermore, response speed is a crucial indicator for the power generation system, making automated operation of the system urgently needed. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a liquid air energy storage and power generation system to solve the problems in the background art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows.

[0007] A liquid air energy storage and power generation system includes a liquid air storage tank for storing liquid air during off-peak electricity demand periods, an evaporator for expanding the liquid air, a heater for heating the expanded air, an expansion turbine for performing work using the high-temperature air, and a controller for controlling the system's operation, all sequentially arranged after the liquid air storage tank. The expansion turbine is connected via a coupling to a generator for converting mechanical energy into electrical energy. A cold storage tank and a variable frequency fan for sending relatively hot air into the evaporator to absorb cold energy and then storing it in the cold storage tank are installed on the heat exchange pipeline of the evaporator. A variable frequency cryogenic pump for pressurizing and delivering liquid air into the evaporator is installed on the pipeline between the liquid air storage tank and the evaporator. The input terminals of the variable frequency cryogenic pump and the variable frequency fan are respectively connected to the output terminal of the controller.

[0008] To further optimize the technical solution, the liquid air storage tank is equipped with a liquid air storage tank outlet control valve for controlling and cutting off the flow of liquid air. A cryogenic pump outlet control valve is installed on the pipeline at the rear end of the variable frequency cryogenic pump. A cryogenic storage tank inlet control valve and a cryogenic storage tank outlet control valve are respectively installed on the pipelines at both ends of the cold storage tank. An expansion turbine main valve is installed at the front end of the expansion turbine to control whether the working fluid enters the expansion turbine. A regulating valve is installed at the front end of the expansion turbine main valve to adjust the system pressure. The input ends of the liquid air storage tank outlet control valve, the cryogenic pump outlet control valve, the cold storage tank inlet control valve, the cold storage tank outlet control valve, the expansion turbine main valve, and the regulating valve are respectively connected to the output end of the controller.

[0009] To further optimize the technical solution, an expansion turbine regulating valve is installed on the pipeline between the expansion turbine main valve and the expansion turbine to regulate the amount of working fluid entering the expansion turbine. The input end of the expansion turbine regulating valve is connected to the output end of the controller.

[0010] To further optimize the technical solution, a cryogenic pump outlet pressure transmitter, a cryogenic pump outlet temperature transmitter, and a cryogenic pump outlet flow transmitter are installed on the pipeline between the variable frequency cryogenic pump and the evaporator to monitor the pressure, temperature, and flow information of the liquid air. An evaporator outlet temperature transmitter and an evaporator outlet pressure transmitter are installed on the pipeline after the evaporator to collect evaporator outlet information. A heater outlet temperature transmitter and a heater outlet pressure transmitter are installed on the pipeline after the heater to monitor the air information after heating. The output terminals of the cryogenic pump outlet pressure transmitter, cryogenic pump outlet temperature transmitter, cryogenic pump outlet flow transmitter, evaporator outlet temperature transmitter, evaporator outlet pressure transmitter, heater outlet temperature transmitter, and heater outlet pressure transmitter are respectively connected to the input terminal of the controller.

[0011] To further optimize the technical solution, the outlet pipe of the variable frequency fan is equipped with a cold storage fan outlet pressure transmitter, a cold storage fan outlet temperature transmitter, and a cold storage fan outlet flow transmitter for collecting information on the heat source entering the evaporator. The pipe between the cold storage tank and the evaporator is equipped with a cold storage tank inlet pressure transmitter and a cold storage tank inlet temperature transmitter for collecting information on the cooling capacity after heat exchange. The output terminals of the cold storage fan outlet pressure transmitter, cold storage fan outlet temperature transmitter, cold storage fan outlet flow transmitter, cold storage tank inlet pressure transmitter, and cold storage tank inlet temperature transmitter are respectively connected to the input terminal of the controller.

[0012] The technological advancements achieved by this utility model are as follows, due to the adoption of the above technical solutions.

[0013] This utility model provides a liquid air energy storage and power generation system. It selects the outlet pressure of the heater as the main gas pressure, which reduces the fluctuation of the main gas pressure. By reasonably setting control valves and temperature, pressure and flow measurement points, the power generation system has the potential for automatic operation. In order to accelerate the response speed of the power generation system, a variable frequency cryogenic pump, a variable frequency fan and an expansion turbine regulating valve are added for feedforward control with the power setpoint as the target, thus realizing the automatic operation of the power generation system. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] The components include: 1. Liquid air storage tank; 2. Liquid air storage tank outlet control valve; 3. Variable frequency cryogenic pump; 4. Evaporator; 5. Cold storage tank; 6. Variable frequency fan; 7. Cryogenic pump outlet control valve; 8. Cryogenic pump outlet pressure transmitter; 9. Cryogenic pump outlet temperature transmitter; 10. Cryogenic pump outlet flow transmitter; 11. Evaporator outlet temperature transmitter; 12. Evaporator outlet pressure transmitter; 13. Cold storage tank outlet control valve; 14. Cold storage tank inlet control valve; 15. Cold storage... 16. Outlet pressure transmitter for cold storage fan; 17. Outlet temperature transmitter for cold storage fan; 18. Outlet flow transmitter for cold storage fan; 19. Inlet pressure transmitter for cold storage tank; 20. Heater; 21. Outlet temperature transmitter for heater; 22. Outlet pressure transmitter for heater; 23. Expansion turbine; 24. Main valve for expansion turbine; 25. Control valve for expansion turbine; 26. Regulating valve; 27. Generator; 28. Generator speed transmitter. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0017] A liquid air energy storage and power generation system, combined with Figure 1As shown, it includes a liquid air storage tank 1, a variable frequency cryogenic pump 3, an evaporator 4, a cold storage tank 5, a variable frequency fan 6, a heater 20, an expansion turbine 23, a generator 27, and a controller. The controller adopts a PID controller.

[0018] The liquid air storage tank 1 is used to store the liquid air stored by the liquid air energy storage liquefaction system during the off-peak electricity period. The liquid air storage tank 1 is equipped with a liquid air storage tank outlet control valve 2, which is used to control the outflow and cut off of liquid air. The input end of the liquid air storage tank outlet control valve 2 is connected to the output end of the controller.

[0019] The variable frequency cryogenic pump 3 is installed on the pipeline at the rear end of the liquid air storage tank 1. A cryogenic pump outlet control valve 7 is installed on the pipeline at the rear end of the frequency converter. A cryogenic pump outlet pressure transmitter 8, a cryogenic pump outlet temperature transmitter 9, and a cryogenic pump outlet flow transmitter 10 are installed on the outlet pipeline of the variable frequency cryogenic pump 3, which are used to monitor the pressure, temperature, and flow information of the liquid air, respectively. The output terminals of the cryogenic pump outlet pressure transmitter, the cryogenic pump outlet temperature transmitter, and the cryogenic pump outlet flow transmitter are respectively connected to the input terminal of the controller. The output terminal of the controller is respectively connected to the input terminal of the variable frequency cryogenic pump and the cryogenic pump outlet control valve.

[0020] Evaporator 4 is connected to variable frequency cryogenic pump 3 to expand liquid air. Evaporator outlet temperature transmitter 11 and evaporator outlet pressure transmitter 12 are installed on the pipeline behind evaporator 4 to collect evaporator outlet temperature and pressure information. The output terminals of evaporator outlet temperature transmitter and evaporator outlet pressure transmitter are respectively connected to the input terminal of controller.

[0021] The heater 20 is connected to the evaporator 4 to heat the expanded air. A heater outlet temperature transmitter 21 and a heater outlet pressure transmitter 22 are installed on the pipeline behind the heater 20 to monitor the heated air information. The output terminals of the heater outlet temperature transmitter and the heater outlet pressure transmitter are respectively connected to the input terminal of the controller.

[0022] An expansion turbine 23 is located at the rear end of the heater 20, utilizing the heated high-temperature air to perform work. An expansion turbine main valve 24 and an expansion turbine regulating valve 25 are located at the front end of the expansion turbine 23. The expansion turbine main valve 24 controls whether the working fluid enters the expansion turbine; it performs a rapid closing action in dangerous situations. The expansion turbine regulating valve 25 regulates the amount of working fluid entering the expansion turbine. A regulating valve 26 is located at the front end of the expansion turbine main valve 24 to adjust the system pressure and prevent overpressure. The input ends of the expansion turbine main valve, the expansion turbine regulating valve, and the regulating valve are connected to the output end of the controller. The heater outlet pressure is selected as the main gas pressure for the expansion turbine; this pressure is also the inlet pressure of the expansion turbine.

[0023] The generator 27 is mounted on the coupling of the expansion turbine 23 to convert mechanical energy into electrical energy. A speed transmitter 28 is mounted on the coupling to monitor the generator speed. The output of the speed transmitter is connected to the output of the controller.

[0024] The cold storage tank 5 and the variable frequency fan 6 are installed on the heat exchange pipeline of the evaporator 4 to provide a heat source for the evaporator and heat the low-temperature liquid air transported in the evaporator. The cold storage tank inlet control valve 14 and the cold storage tank outlet control valve 13 are respectively installed on the pipelines at the front and rear ends of the cold storage tank 5. The input ends of the cold storage tank inlet control valve and the cold storage tank outlet control valve are respectively connected to the output end of the controller.

[0025] The outlet pipe of the variable frequency fan 6 is equipped with a cold storage fan outlet pressure transmitter 15, a cold storage fan outlet temperature transmitter 16, and a cold storage fan outlet flow transmitter 17 to collect heat source information entering the evaporator. The pipe between the cold storage tank 5 and the evaporator 4 is equipped with a cold storage tank inlet pressure transmitter 18 and a cold storage tank inlet temperature transmitter 19 to collect cooling capacity information after heat exchange. The outputs of the cold storage fan outlet pressure transmitter, cold storage fan outlet temperature transmitter, cold storage fan outlet flow transmitter, cold storage tank inlet pressure transmitter, and cold storage tank inlet temperature transmitter are respectively connected to the input of the controller. The variable frequency fan delivers relatively hot air into the evaporator to absorb cooling capacity, which is then stored in the cold storage tank. The cooling capacity is extracted during liquefaction system operation.

[0026] This invention enables the power generation system to operate automatically by rationally setting remote control valves and temperature, pressure and flow measurement points. In order to accelerate the response speed of the power generation system, feedforward control with the power setpoint as the target is added to the variable frequency cryogenic pump, variable frequency fan and expansion turbine regulating valve, thus realizing the automatic operation of the power generation system.

Claims

1. A liquid air energy storage and power generation system, characterized in that: The system includes a liquid air storage tank (1) for storing liquid air during periods of low electricity demand, an evaporator (4) for expanding liquid air, a heater (20) for heating the expanded air, an expansion turbine (23) for performing work using high-temperature air, and a controller for controlling the system's operation. The expansion turbine (23) is connected to a generator (27) for converting mechanical energy into electrical energy via a coupling. A cold storage tank (5) and a variable frequency fan (6) for sending relatively hot air into the evaporator to absorb cold energy and then storing it in the cold storage tank are installed on the heat exchange pipeline of the evaporator (4). A variable frequency cryogenic pump (3) for pressurizing and transporting liquid air into the evaporator (4) is installed on the pipeline between the liquid air storage tank (1) and the evaporator (4). The input ends of the variable frequency cryogenic pump and the variable frequency fan are respectively connected to the output end of the controller.

2. The liquid air energy storage and power generation system according to claim 1, characterized in that: The liquid air storage tank (1) is equipped with a liquid air storage tank outlet control valve (2) for controlling the outflow and cut-off of liquid air. A cryogenic pump outlet control valve (7) is installed on the pipeline at the rear end of the variable frequency cryogenic pump (3). A cryogenic tank inlet control valve (14) and a cryogenic tank outlet control valve (13) are respectively installed on the pipelines at the front and rear ends of the cold storage tank (5). An expansion turbine main valve (24) is installed at the front end of the expansion turbine (23) to control whether the working medium enters the expansion turbine. A regulating valve (26) is installed at the front end of the expansion turbine main valve (24) to adjust the system pressure. The input ends of the liquid air storage tank outlet control valve, the cryogenic pump outlet control valve, the cold storage tank inlet control valve, the cold storage tank outlet control valve, the expansion turbine main valve, and the regulating valve are respectively connected to the output end of the controller.

3. The liquid air energy storage and power generation system according to claim 2, characterized in that: An expansion turbine regulating valve (25) for adjusting the amount of working fluid entering the expansion turbine is provided on the pipeline between the expansion turbine main valve (24) and the expansion turbine (23). The input end of the expansion turbine regulating valve is connected to the output end of the controller.

4. The liquid air energy storage and power generation system according to claim 1, characterized in that: A cryogenic pump outlet pressure transmitter (8), a cryogenic pump outlet temperature transmitter (9), and a cryogenic pump outlet flow transmitter (10) are installed on the pipeline between the variable frequency cryogenic pump (3) and the evaporator (4) for monitoring the pressure, temperature, and flow information of liquid air. An evaporator outlet temperature transmitter (11) and an evaporator outlet pressure transmitter (12) are installed on the pipeline behind the evaporator (4) for collecting evaporator outlet information. A heater outlet temperature transmitter (21) and a heater outlet pressure transmitter (22) are installed on the pipeline behind the heater (20) for monitoring the air information after heating. The output terminals of the cryogenic pump outlet pressure transmitter, the cryogenic pump outlet temperature transmitter, the cryogenic pump outlet flow transmitter, the evaporator outlet temperature transmitter, the evaporator outlet pressure transmitter, the heater outlet temperature transmitter, and the heater outlet pressure transmitter are respectively connected to the input terminal of the controller.

5. A liquid air energy storage and power generation system according to claim 1, characterized in that: The outlet pipe of the variable frequency fan (6) is equipped with a cold storage fan outlet pressure transmitter (15), a cold storage fan outlet temperature transmitter (16), and a cold storage fan outlet flow transmitter (17) for collecting information on the heat source entering the evaporator. The pipe between the cold storage tank (5) and the evaporator (4) is equipped with a cold storage tank inlet pressure transmitter (18) and a cold storage tank inlet temperature transmitter (19) for collecting information on the cooling capacity after heat exchange. The output terminals of the cold storage fan outlet pressure transmitter, the cold storage fan outlet temperature transmitter, the cold storage fan outlet flow transmitter, the cold storage tank inlet pressure transmitter, and the cold storage tank inlet temperature transmitter are respectively connected to the input terminal of the controller.

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