CN114439563A - A sliding pressure expansion compressed air energy storage system and method - Google Patents

Abstract

The invention relates to the technical field of air energy storage, in particular to a sliding pressure expansion compressed air energy storage system and a sliding pressure expansion compressed air energy storage method. The air conditioning branch comprises an auxiliary regenerative heat exchanger, two ends of a high-temperature side runner of the auxiliary regenerative heat exchanger are respectively connected with a high-temperature circulating pump and a low-temperature heat accumulator, an inlet end of a low-temperature side runner of the auxiliary regenerative heat exchanger is connected with an air storage device, and an outlet end of the low-temperature side runner of the auxiliary regenerative heat exchanger is divided into two paths and is respectively connected with an air inlet of a high-pressure air expander and an air inlet of a low-pressure air expander through a flow adjusting device. The sliding pressure expanded compressed air energy storage system and the method can ensure that the output of the whole unit is kept stable while the heat exchange efficiency of a variable working condition is improved, thereby improving the efficiency of the whole system; the variable working condition operation capability of the heat exchange equipment is low in requirement, and the technical difficulty and cost of the system are reduced.

Description

A sliding pressure expansion compressed air energy storage system and method

technical field

The invention relates to the technical field of air energy storage, in particular to a sliding pressure expansion compressed air energy storage system and method.

Background technique

Energy storage, especially the storage of electric energy, is of great significance to the optimization of energy structure and the regulation of power grid operation. The compressed air energy storage system is a new type of large-scale energy storage technology. In the gas storage device; when the electrical load of the power system reaches the peak, the gas storage device releases the stored compressed air, expands in the turboexpander to do work and drives the generator to generate electricity; according to the above principles, the compressed air energy storage system can Complete the conversion of electrical energy-air potential energy-electrical energy.

The compressed air storage device used in the compressed air energy storage system is generally a fixed-volume type. According to the gas state equation, during the deflation process of the fixed-volume pressure vessel, due to the reduction of the gas volume, the gas pressure inside the pressure vessel will follow the deflation process. continuously decreased. Due to the phenomenon of continuous pressure reduction during the deflation process of the fixed-volume compressed air storage device, the air expander, which is the key equipment for compressed air expansion and energy release, needs to have the ability to operate under sliding pressure. For scenarios where the pressure changes greatly during the deflation process of the gas storage device, when the air supply pressure drops seriously, in order to ensure the stable output of the unit, the air expander generally operates in a way that the inlet of the high-pressure machine gradually merges with the inlet of the low-pressure machine. At this time, the conventional heat exchange system cannot meet the high-efficiency heat exchange requirements when the air volume of the air expanders at all levels changes greatly, resulting in a serious drop in the heat exchange efficiency of the system, which in turn affects the operating efficiency of the system. Equipment, on the one hand, the technical difficulty is relatively high, and at the same time, it will also cause the system cost to rise sharply, resulting in a decline in the technical economy of the system.

SUMMARY OF THE INVENTION

Therefore, the technical problem to be solved by the present invention is to overcome the defects in the prior art that during the sliding pressure operation of the air expansion unit, the heat exchanger has a large operating range under variable operating conditions, and the heat exchange efficiency and system efficiency are low, thereby providing a sliding pressure expansion unit. Compressed air energy storage system and method.

The sliding pressure expansion compressed air energy storage system provided by the present invention includes:

The air compression branch, including the air compressor, the high temperature side flow channel of the heat storage heat exchanger and the air storage device in series;

The heat circulation loop is composed of a low temperature heat accumulator, a low temperature circulation pump, a low temperature side flow channel of the heat storage heat exchanger, a high temperature heat accumulator, a high temperature circulation pump, and a heat recovery branch connected in series in sequence. The high temperature side flow channel of the high pressure regenerative heat exchanger and the high temperature side flow channel of the low pressure regenerative heat exchanger are connected in parallel;

The air expansion branch circuit includes an air storage device, a low-temperature side flow channel of a high-pressure regenerative heat exchanger, a high-pressure air expander, a low-temperature side flow channel of a low-pressure regenerative heat exchanger, and a low-pressure air expander connected in series;

The air conditioning branch circuit includes an auxiliary regenerative heat exchanger, and both ends of the high-temperature side flow channel of the auxiliary regenerative heat exchanger are respectively connected to the high-temperature circulating pump and the low-temperature heat accumulator, and the auxiliary regenerative heat exchange The inlet end of the low-temperature side flow channel of the auxiliary heat exchanger is connected to the air storage device, and the outlet end of the low-temperature side flow channel of the auxiliary heat exchanger is divided into two channels and passes through the flow regulating device and the high-pressure air expander respectively. The air inlet of the low pressure air expander is connected with the air inlet.

Optionally, a gas-liquid separator is connected in series between the high temperature side flow channel of the heat storage heat exchanger and the gas storage device.

Optionally, the flow regulating device is a regulating valve.

Optionally, the air compressors are provided with multiple air compressors in series, the heat storage heat exchanger is provided with one and is connected in series after the plurality of air compressors, or the heat storage heat exchanger is provided with at least two air compressors. And it is connected in series after a plurality of air compressors and between two adjacent air compressors.

Optionally, there are at least two auxiliary heat recovery heat exchangers, which are connected in parallel or in series.

The compressed air energy storage method of sliding pressure expansion provided by the present invention is specifically as follows:

Define the intake pressure range of the high-pressure air expander as the high-pressure range, and define the intake pressure range of the low-pressure air expander as the low-pressure range;

In the high pressure range, the flow control device corresponding to the high pressure air expander gradually increases the opening degree to the maximum opening degree, and the flow control device corresponding to the low pressure air expander is closed;

In the low pressure range, the flow control device corresponding to the low pressure air expander gradually decreases the opening degree to close, and the flow control device corresponding to the low pressure air expander gradually increases the opening degree to the maximum opening degree;

When the outlet pressure of the gas storage device is less than the corresponding pressure value in the low pressure interval, the energy release ends.

The technical scheme of the present invention has the following advantages:

1. The sliding pressure expansion compressed air energy storage system provided by the present invention is provided with an air conditioning branch, and the air conditioning branch can further heat the air discharged from the air storage device, and control the entry into the high-pressure air expander and the air through the flow control device. The air flow of the low pressure air expander. On the one hand, it ensures the stability of the air flow range of the heat exchange equipment on the air expansion branch, and on the other hand, it also satisfies the air volume change requirements of different air expansion stages. stability, thereby improving the efficiency of the entire system; because the regulating branch divides the wide range of variable working conditions into two smaller ranges of variable working conditions, through the high/low pressure regenerative heat exchanger, auxiliary regenerative heat exchange Therefore, the heat exchange equipment has lower requirements on the operating capacity of the variable working conditions, and it is easy to use conventional heat exchange equipment to achieve, thereby reducing the technical difficulty and cost of the system.

2. The sliding pressure expansion compressed air energy storage system provided by the present invention is provided with a plurality of auxiliary regenerative heat exchangers, which can realize multiple separations of a large range of variable working conditions, realize finer adjustment of variable working conditions, and improve the Further improve heat exchange efficiency and improve system efficiency.

3. The sliding pressure expansion compressed air energy storage method provided by the present invention has any of the foregoing advantages because it is realized based on the aforementioned compressed air energy storage system.

Description of drawings

In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings required in the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

1 is a schematic structural diagram of a compression energy storage system for sliding pressure expansion in an embodiment of the present invention;

Description of reference numbers:

1. Air compressor; 2. Heat storage heat exchanger; 3. Gas-liquid separator; 4. Air storage device; 5. High-pressure regenerative heat exchanger; 6. High-pressure air expander; 7. Low-pressure regenerative heat exchange 8, low pressure air expander; 9, low temperature heat accumulator; 10, low temperature circulation pump; 11, high temperature heat accumulator; 12, high temperature circulation pump; 13, auxiliary heat recovery heat exchanger; V1, high pressure flow control valve ; V2, low pressure flow control valve.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

Example 1

1, an embodiment of the present invention provides a sliding pressure expansion compressed air energy storage system, including:

The air compression branch includes the air compressor 1, the high temperature side flow channel of the heat storage heat exchanger 2 and the air storage device 4 in series; the thermal cycle circuit consists of the low temperature heat accumulator 9 and the low temperature circulating pump connected in series at the beginning and the end. 10. The low temperature side flow channel of the heat storage heat exchanger 2, the high temperature heat accumulator 11, the high temperature circulation pump 12, and the regenerative branch are composed of the high temperature side flow channel and the low pressure return branch of the high pressure regenerative heat exchanger 5. The high-temperature side flow channels of the heat exchanger 7 are formed in parallel; the air expansion branch includes the air storage device 4, the low-temperature side flow channel of the high-pressure regenerative heat exchanger 5, the high-pressure air expander 6, and the low-pressure regenerative heat exchanger. The low temperature side flow channel of the heat exchanger 7 and the low pressure air expander 8; the air conditioning branch, including the auxiliary heat recovery heat exchanger 13, the two ends of the high temperature side flow channel of the auxiliary heat recovery heat exchanger 13 are respectively connected with the high temperature circulation pump. 12 is connected to the low temperature heat accumulator 9, the inlet end of the low temperature side flow channel of the auxiliary heat recovery heat exchanger 13 is connected to the gas storage device 4, and the outlet end of the low temperature side flow channel of the auxiliary heat recovery heat exchanger 13 is divided into two channels They are respectively connected to the air inlet of the high pressure air expander 6 and the air inlet of the low pressure air expander 8 through the flow regulating device. Among them, the heat storage heat exchanger 2, the high pressure regenerative heat exchanger 5, and the low pressure regenerative heat exchanger 7 are all composed of a high temperature side flow channel and a low temperature side flow channel.

In this embodiment, the air compressor 1 is driven by a motor; in other embodiments, the air compressor 1 can also be driven by other mechanisms such as a pneumatic motor, a hydraulic motor, and the like.

In this embodiment, the heat carrier filled in the thermal cycle loop adopts a liquid working medium; in other embodiments, the heat carrier filled in the thermal cycle loop can also adopt a flowable particle heat storage working medium.

In this embodiment, the flow regulating device is a regulating valve; in other embodiments, the flow regulating device may also be other commonly used structures with a flow regulating function such as a flow regulator. Specifically, in this embodiment, the flow regulating device corresponding to the high pressure air expander 6 is a high pressure flow regulating valve V1, and the flow regulating device corresponding to the low pressure air expander 8 is a low pressure flow regulating valve V2.

In this embodiment, the compression process is unipolar compression, and the expansion process is bipolar series expansion. According to the actual application requirements, the compression process can also adopt the conventional multi-stage series compression, inter-stage/post-stage heat exchange and heat storage process, that is, the air compressor 1 is provided with multiple ones in series, and the heat storage heat exchanger 2 is provided with One and are connected in series after multiple air compressors 1, or at least two heat storage heat exchangers 2 are provided and are connected in series after multiple air compressors 1 and between two adjacent air compressors 1; the expansion process can also be The number of stages can be expanded by adding a plurality of regenerative heat exchangers and expanders in series; correspondingly, two or more auxiliary regenerative heat exchangers 13 can also be arranged in parallel or in series with each other, so as to achieve a finer transformation. Condition flow regulation.

The energy storage process of the compressed air energy storage system of the present embodiment is described in detail below:

The air compressor 1 operates under the drive of the electric motor, sucks in the ambient air and compresses it into a high-temperature compressed gas; the high-temperature compressed gas then enters the high-temperature side flow passage of the heat storage heat exchanger 2, while the low temperature in the low-temperature heat accumulator 9 The heat carrier is driven by the low-temperature circulating pump 10 and enters the low-temperature side flow channel of the heat storage heat exchanger 2 for heat exchange. The high-temperature compressed air cools down to form low-temperature compressed air. The low-temperature compressed air continues to flow downstream and enters the gas storage device 4 for storage. Standby; the low temperature heat carrier absorbs heat and heats up to form a high temperature heat carrier, which is stored in the high temperature heat accumulator 11 for standby use.

The energy release process of the compressed air energy storage system of the present embodiment is described in detail below:

During the energy release process, the gas supply pressure of the gas storage device 4 decreases continuously, and can be divided into a high-pressure interval and a low-pressure interval. The high pressure range, that is, the intake pressure range of the high pressure air expander 6, is lower than this range, the high pressure air expander 6 cannot ensure the stability of the system output by increasing the intake air volume; The air pressure range is lower than this range, the low-pressure air expander 8 cannot ensure the stable output of the system by increasing the suction air volume.

At the beginning of the energy release process in the high pressure range, that is, when the air storage device 4 just begins to deflate, due to the high air storage pressure, the high potential energy of the compressed air, and the large expansion capacity, only a small air flow rate is required to satisfy the stable output of the system need. At this time, both the high-pressure flow regulating device V1 and the low-pressure flow regulating device V2 are in a closed state, and the high-temperature heat carrier in the high-temperature regenerator 11 is driven by the high-temperature circulating pump 12 to enter the high-pressure regenerative heat exchanger and the low-pressure regenerative heat exchanger respectively. In the heat exchanger 7, the exhaust gas of the air storage device 4 is directly reheated, expanded and discharged into the atmospheric environment through the air expansion branch; as the pressure in the air storage device 4 decreases, the air expansion process needs to be increased by increasing the amount of expansion gas. To offset the drop of air potential energy to maintain the system output stable, therefore, the opening of the high-pressure flow regulating valve V1 gradually opens from closing to the maximum opening as the air supply pressure of the air storage device 4 decreases.

When the air supply pressure of the air storage device 4 begins to seriously deviate from the designed intake pressure range of the high-pressure air expander 6, the high-pressure air expander 6 can no longer ensure the stability of the system output by increasing the intake air volume, and the energy release process enters the low-pressure range. The opening of the low-pressure flow control valve V2 is gradually opened from closed, and the opening of the high-pressure flow control valve V1 is gradually closed from full open, thereby increasing the intake air volume of the low-pressure air expander 8 and maintaining the system output stable until the high-pressure flow is adjusted. The valve V1 is completely closed, and the low-pressure flow regulating valve V2 is completely opened; when the low-pressure air expander 8 can no longer meet the stable output demand of the system by increasing the intake air volume, the energy release process ends.

As an improved embodiment, a gas-liquid separator 3 is connected in series between the high temperature side flow channel of the heat storage heat exchanger 2 and the gas storage device 4 . Because liquid may be precipitated after the compressed air is cooled, the low-temperature compressed air can be stored in the gas storage device 4 after dewatering through the gas-liquid separator 3 .

Embodiment 2

The embodiment of the present invention also provides a compressed air energy storage method for sliding pressure expansion, which is specifically as follows:

The intake pressure range of the high-pressure air expander 6 is defined as the high-pressure range, and the intake pressure range of the low-pressure air expander 8 is defined as the low-pressure range; the high-pressure range and the low-pressure range are two continuous pressure ranges, that is, the gas storage device 4 is released During the process, the air supply pressure gradually decreased from the high pressure range to the low pressure range; in the high pressure range, the flow control device corresponding to the high pressure air expander 6 gradually increased the opening to the maximum opening, and the flow control device corresponding to the low pressure air expander 8 Closed; in the low pressure range, the flow control device corresponding to the low pressure air expander 8 gradually reduces the opening degree to close, and the flow control device corresponding to the low pressure air expander 8 gradually increases the opening degree to the maximum opening degree; when the air storage device 4 When the outlet pressure is less than the corresponding pressure value in the low pressure range, the energy release ends.

The sliding pressure expansion compressed air energy storage system and method provided by the present invention, on the one hand, ensures the stability of the air flow rate range of the heat exchange equipment on the air expansion branch, and on the other hand, satisfies the air flow change requirements of different air expansion stages. While improving the heat exchange efficiency of variable working conditions, the output of the entire unit can be kept stable, thereby improving the efficiency of the entire system; because the regulating branch divides the wide variable working condition range into two smaller variable working condition ranges , through the high and low pressure regenerative heat exchanger 7 and the auxiliary regenerative heat exchanger 13, respectively. Therefore, the requirements for the operation capacity of the heat exchange equipment under variable working conditions are relatively low, and it is easy to use conventional heat exchange equipment to achieve, thereby reducing the technical difficulty of the system. and cost.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. And the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (6)

1. a compressed air energy storage system of sliding pressure expansion, is characterized in that, comprises: An air compression branch, comprising an air compressor (1), a high temperature side flow channel of a heat storage heat exchanger (2) and an air storage device (4) connected in series in sequence; A heat circulation loop, which consists of a low temperature heat accumulator (9), a low temperature circulation pump (10), a low temperature side flow passage of the heat storage heat exchanger (2), a high temperature heat accumulator (11), and a high temperature circulation pump, which are connected in series in sequence. (12), a regenerative branch is formed, and the regenerative branch is formed in parallel by the high temperature side flow channel of the high pressure regenerative heat exchanger (5) and the high temperature side flow channel of the low pressure regenerative heat exchanger (7); The air expansion branch circuit includes an air storage device (4), a low temperature side flow channel of a high pressure regenerative heat exchanger (5), a high pressure air expander (6), and a low temperature regenerative heat exchanger (7) connected in series in sequence Side runner and low pressure air expander (8); The air conditioning branch includes an auxiliary regenerative heat exchanger (13), the two ends of the high temperature side flow channel of the auxiliary regenerative heat exchanger (13) are respectively connected with the high temperature circulation pump (12) and the low temperature heat accumulator (9) Connection, the inlet end of the low-temperature side flow channel of the auxiliary regenerative heat exchanger (13) is connected to the gas storage device (4), and the low-temperature side flow of the auxiliary regenerative heat exchanger (13) The outlet end of the channel is divided into two paths and is respectively connected to the air inlet of the high pressure air expander (6) and the air inlet of the low pressure air expander (8) through a flow regulating device. 2. The sliding pressure expansion compressed air energy storage system according to claim 1, wherein the high temperature side flow channel of the heat storage heat exchanger (2) and the gas storage device (4) are connected in series There is a gas-liquid separator (3). 3 . The sliding pressure expansion compressed air energy storage system according to claim 1 , wherein the flow regulating device is a regulating valve. 4 . 4. The compressed air energy storage system of sliding pressure expansion according to any one of claims 1-3, characterized in that: The air compressors (1) are provided with a plurality of connected in series; The heat storage heat exchanger (2) is provided with one and is connected in series after a plurality of air compressors (1), or the heat storage heat exchanger (2) is provided with at least two and is connected in series with a plurality of air compressors After (1) and between two adjacent air compressors (1). 5. The sliding pressure expansion compressed air energy storage system according to any one of claims 1-3, characterized in that, the auxiliary heat recovery heat exchangers (13) are provided with at least two, which are connected in parallel or in series with each other . 6. A method for a compressed air energy storage system based on the sliding pressure expansion described in any one of claims 1-5, characterized in that: The intake pressure range of the high pressure air expander (6) is defined as the high pressure range, and the intake pressure range of the low pressure air expander (8) is defined as the low pressure range; In the high pressure range, the flow control device corresponding to the high pressure air expander (6) gradually increases the opening degree to the maximum opening degree, and the flow control device corresponding to the low pressure air expander (8) is closed; In the low pressure interval, the flow control device corresponding to the low pressure air expander (8) gradually reduces the opening degree to close, and the flow control device corresponding to the low pressure air expander (8) gradually increases the opening degree to the maximum opening degree; When the gas outlet pressure of the gas storage device (4) is less than the pressure value corresponding to the low pressure interval, the energy release ends.

Images