CN205227998U - Liquid precooling working medium cold storage system - Google Patents

Abstract

The utility model provides a liquid pre-cooling working medium cold storage system, which is used for low-temperature liquid air energy storage, which includes a cold storage heat exchange unit, a cold release heat exchange unit and a working medium storage unit for storing liquid precooling working medium. The working medium storage unit is connected between the cold storage and heat exchange unit and the cooling release heat exchange unit, forming a channel for the liquid precooling working medium to circulate, exchange heat and store in liquid phase. The liquid precooling working medium cold storage system uses the liquid medium in the room temperature-liquid nitrogen temperature range as the cold storage working medium, and uses the heat exchanger as the cooling capacity exchange device, which can realize a very small heat transfer temperature difference inside the heat exchanger, reducing Loss in the heat transfer process, which is conducive to improving the energy storage efficiency of the system.

Description

Liquid precooling refrigerant storage system

technical field

The utility model relates to the technical field of energy storage, in particular to a liquid precooling working medium cold storage system for low-temperature liquid air energy storage.

Background technique

At present, with the increasing popularity of renewable energy, the importance of large-scale energy storage systems in the power system has become increasingly prominent. Large-scale power energy storage technology can effectively solve the problem of unstable power generation of intermittent energy sources such as wind energy, solar energy, and tidal energy. As an emergency uninterruptible power supply.

By the end of 2013, the total installed capacity of wind power in my country was 91.4GW, and the total installed capacity of solar power was 10GW; it is estimated that by 2020, the total installed capacity of wind power in my country will reach 200GW, and the total installed capacity of solar power will reach 50GW. Corresponding to the vigorous development of renewable energy is the phenomenon of a large number of curtailment of wind and electricity curtailment caused by the inherent intermittency and instability of renewable energy. Among them, the annual average utilization hours of large-scale wind power in China in 2014 was too low (average 1893h). As a flexible adjustment method, large-scale energy storage technology can effectively store electric energy for a long time and quickly feed it back to the grid, thereby improving the ability of the power system to gather large-scale wind power and photovoltaic power generation; large-scale energy storage systems and renewable energy synergy The control will make the power supply output from the large-scale wind and solar power station to the receiving power system stable, reliable and stable, which will help improve the safety of the system operation and improve the power grid's ability to accept new energy power generation.

Conventional energy storage technologies mainly include flywheel energy storage, battery energy storage, superconducting energy storage, supercapacitor energy storage, pumped water energy storage, compressed air energy storage and liquid air energy storage, etc. However, the energy storage technologies that can sustain large-capacity output for several hours mainly include: pumped hydro storage, battery energy storage, compressed air energy storage, and liquid air energy storage. Thousands of megawatt hours) technology for energy storage applications.

Pumped storage requires sufficient terrain differences, and the construction of reservoirs has a greater impact on ecology and the surrounding environment. Compared with pumped storage, compressed air has less stringent requirements on the natural environment. The working principle of traditional compressed air energy storage system is similar to that of pumped storage. When the power consumption of the power system is at a low point, the system stores energy Use the surplus electricity in the system to drive the air compressor to compress the air, and store the energy in the form of compressed air in the gas storage device; The compressed air in the gas storage space is released, enters the combustion chamber of the gas turbine and burns together with the fuel, and then drives the turbine to generate electricity. However, the energy storage density of compressed air energy storage is still relatively low, requiring a large volume of gas storage space. For example, the energy storage capacity of the Huntorf Power Station in Germany is 290*3MWh, and the gas storage volume needs to be 310,000 cubic meters, which directly limits the further development of compressed air energy storage. develop.

In order to overcome the limitation of gas storage space, scholars at home and abroad have successively carried out research on liquid air energy storage technology in recent years. The liquid air energy storage system uses low-temperature liquid air as the energy storage medium, and the high density of liquid air greatly increases the energy storage density of the system. It is 7-10 times that of the compressed air energy storage system.

When the liquid air energy storage system stores energy, it uses low-valley electric energy to drive the compressor to compress the air, and uses the cold energy stored in the previous cycle to cool and liquefy the air and then enters the low-temperature storage tank for storage; when the liquid air energy storage system releases energy, it uses low-temperature The pump draws the liquid air from the low-temperature storage tank to pressurize it, and uses the low-temperature cold storage system to recover and store the cold energy in the rewarming process of the liquid air, so that after it absorbs heat and reheats, it drives the turbo expander to drive the generator to do work, and at the same time, the low-temperature cold storage The system recovers and stores the cold energy in the liquid air for the next cycle of air cooling and liquefaction. The operating efficiency of the liquid air energy storage system depends on the efficiency of the cold energy recovery and utilization process in the cold storage process.

In the current research, the cold storage system mainly uses solid medium or solid-liquid phase change material as the cold storage medium. Among the solid materials, rocks, ceramics, and metal blocks are used to store cold energy by using the sensible heat of the cold storage medium. However, due to the heat conduction of the solid medium in the process of cold storage and cooling, a large unsteady heat transfer temperature difference is generated, and the current cold storage efficiency is average. It can only reach 50%, which makes it impossible to meet the overall liquefaction requirements; the other type is solid-liquid phase change latent heat storage medium, such as one or more of ammonia and its aqueous solution, salt aqueous solution, alcohols and their aqueous solution, but currently They have not been used as phase change heat storage materials from room temperature to liquid nitrogen temperature region. Therefore, there is an urgent need to develop new high-efficiency cold storage systems for cryogenic liquid air energy storage.

Utility model content

In view of this, in order to overcome the defects and problems of the prior art, the utility model provides a liquid precooling working medium cold storage system for low-temperature liquid air energy storage.

A liquid precooling working medium cold storage system is used for low-temperature liquid air energy storage, which includes a cold storage heat exchange unit, a cooling release heat exchange unit, and a working medium storage unit for storing liquid precooling working medium. The working medium storage unit It is connected between the cold storage and heat exchange unit and the cooling release heat exchange unit, forming a channel for the liquid precooling working fluid to circulate, exchange heat and store in liquid phase.

In a preferred embodiment of the present invention, the cold storage heat exchange unit includes a plurality of first heat exchangers connected in series, the cooling release heat exchange unit includes a plurality of second heat exchangers connected in series, and the working fluid The storage unit includes a plurality of cold-state working fluid storages and a plurality of hot-state working fluid storages, the first heat exchanger, the hot-state working fluid storage, the second heat exchanger and the cold-state The working fluid storages correspond to each other and are sequentially connected through pipelines to form channels for the liquid precooling working fluid to circulate, exchange heat and store in liquid phase.

In a preferred embodiment of the present utility model, between the hot working medium storage and the second heat exchanger, between the cold working medium storage and the first heat exchanger, there are There is a regulating valve for regulating the flow rate of the liquid precooling working medium.

In a preferred embodiment of the present invention, a throttle valve and a liquid storage tank are also included, and the high-pressure air sequentially passes through the plurality of first heat exchangers to exchange heat and cool down step by step, and is throttled and liquefied by the throttle valve. Stored in the liquid storage tank as liquid air.

In a preferred embodiment of the present invention, the unliquefied air in the liquid storage tank flows through the plurality of first heat exchangers in the opposite flow direction to the high-pressure air.

In a preferred embodiment of the present invention, the liquid air in the liquid storage tank is pumped out by the cryopump, and is gradually heated by the plurality of second heat exchangers to form expanded air.

In a preferred embodiment of the present utility model, the first heat exchanger and the second heat exchanger are finned plate heat exchangers or coiled tube heat exchangers.

In a preferred embodiment of the present utility model, the operating temperature range of the liquid precooling medium is -196°C to 50°C.

In a preferred embodiment of the present invention, the liquid precooling medium is R123 refrigerant, propane, pentane or a combination thereof.

Compared with the prior art, the liquid pre-cooling working medium cold storage system provided by the utility model adopts the liquid medium in the room temperature-liquid nitrogen temperature range as the cold storage working medium, and uses the heat exchanger as the cooling capacity exchange device, which can be realized inside the heat exchanger The very small heat transfer temperature difference reduces the loss during the heat transfer process, which is conducive to improving the energy storage efficiency of the system.

Description of drawings

Fig. 1 is the schematic diagram of composition of the liquid precooling working fluid cold storage system provided by the utility model;

Fig. 2 is a schematic diagram of the working state of the liquid precooling working fluid cold storage system shown in Fig. 1 .

detailed description

In order to facilitate the understanding of the utility model, the utility model will be described more fully below with reference to the relevant drawings. Preferred embodiments of the utility model are provided in the accompanying drawings. The above are only preferred embodiments of the present utility model, and are not intended to limit the patent scope of the present utility model. Any equivalent structure or equivalent process conversion made by using the description of the utility model and the contents of the accompanying drawings, or directly or indirectly used in other related All technical fields are all included in the scope of patent protection of the utility model in the same way.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of this invention. The terminology used herein in the description of the utility model is only for the purpose of describing specific implementations, and is not intended to limit the utility model. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Please refer to Fig. 1, a preferred embodiment of the present invention provides a liquid pre-cooling refrigerant cold storage system for low-temperature liquid air energy storage, which includes a cold storage heat exchange unit 10, a cold release heat exchange unit 20 and a storage liquid A working fluid storage unit 30 for precooling working fluid, the working fluid storage unit 30 is connected between the cold storage heat exchange unit 10 and the cooling release heat exchange unit 20 to form the liquid precooling Channels for phase circulation, heat exchange and storage.

In this embodiment, the cold storage heat exchange unit 10 includes a plurality of first heat exchangers 11 connected in series, the cooling release heat exchange unit 20 includes a plurality of second heat exchangers 21 connected in series, and the working fluid storage The unit 30 includes a plurality of cold working fluid storages 31 and a plurality of hot working fluid storages 33, the first heat exchanger 11, the hot working fluid storage 33, the second heat exchanger 21 One-to-one correspondence with the cold-state working fluid storages 33, and sequentially connected through the pipeline 40 to form a channel for the liquid pre-cooled working fluid to circulate, heat exchange and store in liquid phase. It can be understood that both the cold storage and heat exchange unit 10 and the cooling release heat exchange unit 20 include n-stage heat exchangers (n is a natural number), and the liquid pre-cooling working medium is an n-stage heat exchanger.

Preferably, the first heat exchanger 11 and the second heat exchanger 21 are fin-plate heat exchangers or wound-tube heat exchangers. Thus, the large heat exchange area of the first heat exchanger 11 and the second heat exchanger 21 can be utilized to realize efficient heat exchange with a small temperature difference.

Preferably, the use temperature range of the liquid pre-cooling refrigerant is -196°C to 50°C, that is, the liquid pre-cooling refrigerant is distributed according to the room temperature-liquid nitrogen temperature range. Thus, the liquid pre-cooling working medium cold storage system adopts the liquid pre-cooling medium in the room temperature-liquid nitrogen temperature range as the cold storage working medium, and the first heat exchanger 11 of the cold storage heat exchange unit 10 and the The second heat exchanger 21 of the cooling and heat exchange unit 20 is used as a cooling capacity exchange device, which can realize a very small heat transfer temperature difference inside the heat exchanger, reduce the loss in the heat transfer process, and thus help to improve energy storage efficiency.

In this embodiment, the liquid pre-cooling refrigerant used is a combination of various refrigerants to ensure that no solidification and gasification occurs under working conditions. Specifically, the liquid pre-cooling refrigerant is R123 refrigerant, propane, pentane or its combination.

Further, regulating valves are provided between the hot working fluid storage 33 and the second heat exchanger 21 , and between the cold working fluid storage 31 and the first heat exchanger 11 50 , used to adjust the flow rate of the liquid precooling medium to ensure the heat exchange efficiency between the second heat exchanger 21 and the first heat exchanger 11 .

In this embodiment, the liquid precooling working fluid cold storage system also includes a throttle valve and a liquid storage tank (not shown in the figure), and the high-pressure air sequentially passes through the plurality of first heat exchangers 11 to exchange heat and cool down step by step, and After being throttled and liquefied by the throttle valve, it is stored in the liquid storage tank as liquid air. The liquid air in the liquid storage tank is pumped out by a cryopump (not shown in the figure), and is gradually heated through the plurality of second heat exchangers 21 to form expanded air. At the same time, the unliquefied air in the liquid storage tank flows back through the plurality of first heat exchangers 11 in the opposite flow direction to the high-pressure air, that is, the unliquefied air forms backflow air. Obviously, the unliquefied air cools the high-pressure air step by step when it flows back through the plurality of first heat exchangers 11, so that the heat exchange and cooling efficiency of the high-pressure air can be effectively improved, and then the cooling capacity of the cold storage can be improved. The cold storage efficiency of the heat exchange unit 10 .

Please refer to Figure 2, the working principle of the liquid pre-cooled working medium cold storage system including the cold storage process and the cold release process is as follows:

Cold storage process: before starting, liquid working fluid 1 to liquid working medium n are in a cold state, and the internal cooling capacity of the liquid pre-cooling working medium cold storage system is stored in the form of internal energy of the liquid working medium; during the cold storage process, the cold state The liquid working medium 1 to liquid working medium n, according to the distribution of the room temperature-liquid nitrogen temperature zone, in the heat exchanger 1 to the heat exchanger n, heat exchange with high-pressure air step by step, and the liquid working medium at each level (liquid working medium 1 to liquid working medium n) are heated to store in a hot state, the high-pressure air is cooled step by step, and the obtained low-temperature liquid air enters the throttle valve to throttle and liquefy, and is stored in the liquid storage tank as liquid air. While obtaining liquid air during the liquefaction process, the throttling and cooling process is completed to supplement cooling capacity, complete the cooling capacity balance of the system, and avoid external cooling capacity input. During the entire cold storage process, the cold energy completes the transfer process from the liquid working medium to the liquid air.

Cooling process: the hot liquid working medium 1 to liquid working medium n, according to the distribution of room temperature - liquid nitrogen temperature zone, in the heat exchanger 1 to heat exchanger n, heat exchange with liquid air step by step, each level of liquid The working medium is cooled into a cold state for storage, and the stored low-temperature liquid air is rewarmed step by step, and the obtained expanded air enters the expansion unit to expand and perform work to output energy (that is, the expansion process), and the cooling capacity completes the transfer process from liquid air to liquid working medium.

Both the cold storage process and the cooling release process use the regulating valve 50 to realize the flow regulation of the liquid working medium 1 to the liquid working medium n, and ensure the heat exchange efficiency.

Compared with the prior art, the liquid pre-cooling working medium cold storage system provided by the utility model adopts the liquid pre-cooling working medium in the room temperature-liquid nitrogen temperature zone as the cold storage working medium, and uses the heat exchanger as the cooling capacity exchange device, which can be used in heat exchange A very small heat transfer temperature difference is realized inside the device, reducing the loss in the heat transfer process, which is conducive to improving the energy storage efficiency of the system, that is, using the high specific heat, wide temperature range and efficient heat transfer efficiency of the liquid pre-cooling medium to improve efficiency, Therefore, the efficiency of the liquid precooling working medium cold storage system is greatly improved.

The above-mentioned embodiments only express several implementations of the utility model, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the patent scope of the utility model. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the scope of protection of the utility model patent should be based on the appended claims.

Claims (9)

1. A liquid precooling working medium cold storage system, which is used for low-temperature liquid air energy storage, is characterized in that it includes a cold storage heat exchange unit, a cooling release heat exchange unit, and a working medium storage unit for storing liquid precooling working medium. The working medium storage unit is connected between the cold storage and heat exchange unit and the cooling release heat exchange unit, forming a channel for the liquid precooling working medium to circulate, exchange heat and store in liquid phase. 2. The liquid precooling working fluid cold storage system according to claim 1, wherein the cold storage heat exchange unit comprises a plurality of first heat exchangers connected in series, and the cooling release heat exchange unit comprises a plurality of series connected heat exchangers. The second heat exchanger, the working fluid storage unit includes a plurality of cold working fluid storage and a plurality of hot working fluid storage, the first heat exchanger, the hot working fluid storage, the The second heat exchanger is in one-to-one correspondence with the cold-state working fluid storage, and is sequentially connected through pipelines to form a channel for the liquid pre-cooling working fluid to circulate, exchange heat and store in liquid phase. 3. The liquid precooling working fluid cold storage system according to claim 2, characterized in that, between the hot working fluid storage and the second heat exchanger, between the cold working fluid storage and the second heat exchanger A regulating valve for regulating the flow rate of the liquid precooling working medium is provided between the first heat exchangers. 4. The liquid precooling working medium cold storage system as claimed in claim 3, further comprising a throttle valve and a liquid storage tank, and the high-pressure air sequentially passes through the plurality of first heat exchangers for step-by-step heat exchange and cooling, After passing through the throttling valve and liquefied, it is stored in the liquid storage tank as liquid air. 5. The liquid precooling working medium cold storage system according to claim 4, characterized in that, the unliquefied air in the liquid storage tank flows back through the plurality of first exchangers in the opposite flow direction to the high-pressure air. heater. 6. The liquid precooling working medium cold storage system according to claim 4, characterized in that, the liquid air in the liquid storage tank is drawn out by the cryopump and passed through the plurality of second heat exchangers to heat up step by step Expanding air is formed. 7. The cold storage system for liquid precooling working medium according to claim 2, characterized in that, the first heat exchanger and the second heat exchanger are fin-plate heat exchangers or wound-tube heat exchangers. 8. The cold storage system of liquid pre-cooling working fluid according to claim 1, characterized in that the operating temperature range of the liquid pre-cooling working medium is -196°C to 50°C. 9. The liquid precooling refrigerant cold storage system according to claim 1, wherein the liquid precooling refrigerant is R123 refrigerant, propane, pentane or a combination thereof.