Energy storage system coupled with external compression air separation system and energy storage and release method thereof

Abstract

The invention provides an energy storage system coupled with an external compression air separation system, which comprises the external compression air separation system, and a cold energy storage system and an energy release system which are additionally arranged on the external compression air separation system, the cold energy storage system comprises a high-temperature heat exchanger, a low-temperature heat exchanger and two propane storage tanks; the high-temperature heat exchanger is provided with three high-temperature heat exchanger fluid heat exchange channels; the low-temperature heat exchanger is provided with four low-temperature heat exchanger fluid heat exchange channels; the energy release system comprises an air blower, a second cooler and a second air compressor; and the other end of the second cooler is connected with the pre-cooling system. In the energy storage and release process, the operation condition of the rectification system is kept unchanged, and the oxygen and nitrogen productivity and purity are not affected; the cold energy storage system stores / releases cold energy of different temperature areas, the irreversible smooth loss of the system is reduced, and the energy storage efficiency is improved.

Description

Technical Field

[0001] This invention relates to the fields of cold storage, liquefied air energy storage and air separation technology, and in particular to an energy storage system coupled with an external compression air separation system and its energy storage and release methods. Background Technology

[0002] With the development of the market economy and the continuous expansion of electricity demand, the peak-valley difference in power supply has become more pronounced. The installed capacity of renewable energy power generation such as wind and solar power has been increasing year by year. By the end of 2023, wind and solar power generation accounted for 15.3% of the total electricity consumption, placing higher demands on the adaptability and frequency and voltage regulation capabilities of the power grid. To address these issues, developing large-scale energy storage technology has become a strategic goal of national energy technology development. Currently, commonly used large-scale physical energy storage technologies include pumped hydro storage, compressed air storage, and liquefied air storage. Pumped hydro storage and compressed air storage technologies are constrained by geographical location and site selection, limiting their development. However, liquefied air storage technology, due to its unique advantages such as high energy density, short response time, high safety factor, wide availability of raw materials, and lack of geographical and environmental limitations, is widely considered a promising large-scale energy storage method.

[0003] Air separation units are core equipment for producing industrial gases—the "lifeblood" of industry. From traditional industries like petrochemicals, coal mining, and steel to emerging industries like electronics, semiconductors, and biopharmaceuticals, there is a significant demand for industrial gases. With the scaling up and integration of traditional industries such as coal chemical and oil refining projects, outdated production capacity is gradually being phased out. Consequently, the metallurgical air separation industry generally faces multiple crises, including production cuts, shutdowns, and equipment idleness. Air separation units in some chemical sectors are also operating at reduced capacity, resulting in designed capacity generally exceeding actual gas demand and significant air separation gas loss. Therefore, utilizing air separation units for large-scale energy storage technology would be crucial for improving the current situation of overcapacity in air separation process capacity and saving on investment costs for energy storage systems.

[0004] Due to the compatibility of air separation and liquefied air energy storage technologies in terms of cooling temperature range and equipment utilization, choosing to use air separation process equipment to achieve large-scale storage of liquefied air can not only reduce the amount of equipment used and the production, operation, and maintenance costs of the equipment, but also fully tap the operating potential of air separation equipment, reduce the amount of product gas emitted from the air separation system, improve equipment utilization, and realize the large-scale, ultra-large-scale, multi-functional, and integrated development of air separation equipment and process technology.

[0005] The air separation unit is integrated with the liquefied air energy storage system. Without affecting the normal operation of the air separation unit, the compression, cooling and purification equipment in the air separation system can be shared with the liquefied air energy storage system.

[0006] Existing technologies, such as Chinese invention patent applications CN113670003A, CN113686099A, CN112145248A, CN111043833A, and CN111811213A, propose liquefied air energy storage integrated systems for internal / external compressed air separation systems. These integrated systems utilize low-cost off-peak electricity to store externally supplied air in liquid form in cryogenic storage tanks, beyond the product user's load demand. During peak or off-peak electricity periods, the stored cryogenic liquid air is used to recover high-grade cold energy through heat exchange equipment, and then outputs electrical energy through a turbine expansion power generation device, while recovering all the cryogenic pure air output from the expansion.

[0007] Thermodynamic analysis of the above process flow reveals that the main reasons for the low system efficiency are: using only liquefied air as the energy storage medium, there is excess cold energy in a certain temperature range during the energy storage / release process of the air separation process. Summary of the Invention

[0008] This invention provides an energy storage system coupled with an external compression air separation system and its energy storage and release method, in order to solve the technical problem of excess cold in a certain temperature range during energy storage / release and heat exchange in the main heat exchanger in the existing air separation process.

[0009] The technical solution provided by this invention is as follows:

[0010] One object of the present invention is to provide an energy storage system coupled to an external compressed air separation system, the energy storage system comprising an external compressed air separation system, and a cold energy storage system and an energy release system added to the external compressed air separation system;

[0011] The external compression air separation system includes a precooling system, a purification system, an air compression / expansion system, a main heat exchanger, and a distillation system;

[0012] The air compression / expansion system includes a first air compressor, a booster compressor, a first cooler, and an expander; the first air compressor is connected to the precooling system, the precooling system is connected to the purification system, the purification system is connected to the booster compressor, and the booster compressor is connected to the first cooler;

[0013] The first cooler is connected to the main heat exchanger; the main heat exchanger is connected to the distillation system and the expander; the expander is connected to the distillation system.

[0014] The cold energy storage system includes a high-temperature heat exchanger, a low-temperature heat exchanger, and two propane storage tanks; the high-temperature heat exchanger has three high-temperature heat exchanger fluid heat exchange channels; and the low-temperature heat exchanger has four low-temperature heat exchanger fluid heat exchange channels.

[0015] The energy release system includes a blower, a second cooler, and a second air compressor; one end of the second cooler is connected to the blower, and the other end is connected to the precooling system.

[0016] The first high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger is connected to the first cooler at one end and to the expander at the other end.

[0017] One end of the second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger is connected to the purification system, and the other end is connected to the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger.

[0018] The second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger is connected to one end of the purification system and also to the first air compressor;

[0019] One end of the third high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger is connected to the precooling system, and the other end is connected to the third low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger.

[0020] The first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger is connected to the distillation system.

[0021] The second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger is connected to the expander, the distillation system, and the second air compressor; the second air compressor is connected to the first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger.

[0022] The third low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger is connected to the nitrogen-sludge pipeline between the main heat exchanger and the distillation system.

[0023] The two ends of the fourth low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger are respectively connected to the two propane storage tanks.

[0024] In a preferred embodiment, the distillation system includes a first subcooler, a lower column of the distillation column, a main cooler of the distillation column, an upper column of the distillation column, and a second subcooler.

[0025] One end of the first subcooler is connected to the expander and the main heat exchanger; the other end of the first subcooler is connected to the upper column of the distillation column and the main cooler of the distillation column.

[0026] In a preferred embodiment, the second cryogenic heat exchanger fluid heat exchange channel of the cryogenic heat exchanger is connected to the pipe between the expander and the first subcooler of the distillation system.

[0027] In a preferred embodiment, the main heat exchanger is connected to the lower column of the distillation column;

[0028] The first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger is a pipeline connecting the main heat exchanger and the lower column of the distillation column of the distillation system.

[0029] In a preferred embodiment, the cold storage medium of the propane storage tank in the cold energy storage system is a single or mixed fluid of methanol, ethanol, methane, propane, butane, and carbon dioxide, or a solid particle bed cold storage is used.

[0030] Another object of the present invention is to provide an energy storage method for an energy storage system coupled with an external compression air separation system. During off-peak electricity periods, the energy storage system provided by the present invention is used for energy storage, comprising the following methods:

[0031] The precooling system, purification system and air compression / expansion system of the external compression air separation system will increase their operating load, while the main heat exchanger and distillation system will maintain their operating conditions.

[0032] The first air flow rate is drawn from the first cooler and enters the first high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger for cooling. Then it is introduced into the expander to obtain low-temperature air.

[0033] Low-temperature air enters the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger and exchanges heat with the propane stream in the fourth low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, storing the low-temperature coldness of the low-temperature air in two propane storage tanks.

[0034] After passing through the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, the low-temperature air enters the second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger, where it exchanges heat with the first air flow in the first high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger. The low-temperature air after heat exchange returns to the first air compressor for compression.

[0035] Another aspect of the present invention provides an energy release method for an energy storage system coupled to an external compressed air separation system. During peak power periods, the energy storage system coupled to an external compressed air separation system provided by the present invention is used for energy release, comprising the following methods:

[0036] The air compression / expansion system of the external compression air separation system operates at a reduced load, the main heat exchanger operates at a reduced load, and the precooling system, purification system and distillation system maintain their operating conditions unchanged.

[0037] A second gas flow is drawn from the external environment, compressed by a blower, and then passes through a second cooler, a precooling system, and a purification system. It then enters the second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger and the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger for cooling. After cooling, the second gas flow enters the upper column of the distillation column of the distillation system.

[0038] After the main heat exchanger is operated at reduced load, the excess amount of polluted nitrogen in the polluted nitrogen pipeline between the main heat exchanger and the distillation system enters the third low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger and the third high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger in sequence, cooling the second gas flow rate in the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, the second gas flow rate in the first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, and the second gas flow rate in the second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger.

[0039] The excess nitrogen waste enters the precooling system after passing through the fluid heat exchange channel of the third high-temperature heat exchanger of the high-temperature heat exchanger.

[0040] In a preferred embodiment, the second gas flow rate, cooled by the fluid heat exchange channel of the second low-temperature heat exchanger, enters the second air compressor for compression.

[0041] The second air flow after compression by the second air compressor enters the fluid heat exchange channel of the first low-temperature heat exchanger for cooling.

[0042] After cooling, the second gas flow rate enters the lower column of the distillation column of the distillation system.

[0043] In a preferred embodiment, the propane stream in the fourth low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger cools the second gas flow rate entering the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger and the second gas flow rate in the first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger.

[0044] The above-described technical solution of the present invention has at least the following beneficial effects compared with the prior art:

[0045] This invention provides an energy storage system coupled with an external compression air separation system and its energy storage and release method. With the goal of improving the energy storage scale and energy storage efficiency of the energy storage system, and combined with the characteristics of the air separation process, propane, ethanol and other energy storage media are used to store cold energy in multiple temperature zones and in multiple ways, thereby reducing irreversible losses in the energy storage and peak shaving process of the system.

[0046] This invention provides an energy storage system coupled to an external compressed air separation system and its energy storage and release method. The cold energy storage system and the energy release system are coupled to the external compressed air separation system as one unit. By utilizing the excess design load of the original external compressed air separation system, the amount of equipment used is reduced, thereby achieving the goal of saving initial investment costs.

[0047] This invention provides an energy storage system coupled with an external compressed air separation system and its energy storage and release method. During the energy storage and release process, the operating conditions of the distillation system remain unchanged, without affecting the oxygen and nitrogen production capacity and purity. The cold energy storage system stores / releases cold energy in different temperature zones, reducing irreversible losses and improving energy storage efficiency. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the structure of a conventional external compression air separation system in existing technology.

[0050] Figure 2 This is a schematic diagram of the energy storage system of a coupled external compression air separation system according to the present invention.

[0051] Explanation of reference numerals in the attached figures:

[0052] 201. First air compressor; 202. Booster compressor; 203. First cooler; 204. Expander; 205. Main heat exchanger; 206. First subcooler; 207. Lower column of distillation column; 208. Main cooler of distillation column; 209. Upper column of distillation column; 210. Second subcooler;

[0053] A201, High-temperature heat exchanger; A202, Low-temperature heat exchanger; A203, Propane storage tank; A204, Blower; A205, Secondary cooler; A206, Secondary air compressor;

[0054] G1, fluid heat exchange channel of the first high-temperature heat exchanger; G2, fluid heat exchange channel of the second high-temperature heat exchanger; G3, fluid heat exchange channel of the third high-temperature heat exchanger.

[0055] D1, fluid heat exchange channel of the first low-temperature heat exchanger; D2, fluid heat exchange channel of the second low-temperature heat exchanger; D3, fluid heat exchange channel of the third low-temperature heat exchanger; D4, fluid heat exchange channel of the fourth low-temperature heat exchanger.

[0056] Q5, First air flow rate; Q6, Second air flow rate. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0058] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0059] It should be noted that the terms "up", "down", "left", "right", "front", and "back" used in this invention are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0060] Combination Figure 1 and Figure 2 According to an embodiment of the present invention, an energy storage system coupled to an external compressed air separation system is provided, comprising an external compressed air separation system, and a cold energy storage system and an energy release system added to the external compressed air separation system.

[0061] The external compression air separation system is an existing conventional external compression air separation system, such as Figure 1 As shown. Comparison Figure 1 and Figure 2 The present invention adds a cold energy storage system and an energy release system to the external compressed air separation system.

[0062] According to an embodiment of the present invention, the external compression air separation system includes a precooling system, a purification system, an air compression / expansion system, a main heat exchanger 205, and a distillation system.

[0063] The air compression / expansion system includes a first air compressor 201, a booster compressor 202, a first cooler 203, and an expander 204. The first air compressor 201 is connected to a precooling system, the precooling system is connected to a purification system, the purification system is connected to the booster compressor 202, and the booster compressor 202 is connected to the first cooler 203.

[0064] The distillation system includes a first subcooler 206, a lower column of the distillation column 207, a main cooler of the distillation column 208, an upper column of the distillation column 208, and a second subcooler 210.

[0065] The first cooler 203 is connected to the main heat exchanger 205; the main heat exchanger 205 is connected to the distillation system and the expander 204. Further, the main heat exchanger 205 is connected to the lower column 207 of the distillation column of the distillation system.

[0066] Furthermore, the expander 204 is connected to the upper column 209 of the distillation system via the first subcooler 206. Specifically, one end of the first subcooler 206 is connected to the expander 204 and the main heat exchanger 205. The other end of the first subcooler 206 is connected to the upper column 209 of the distillation system and the main cooler 208 of the distillation system.

[0067] The second subcooler 210 is connected at one end to the upper column 209 of the distillation column and at the other end to the lower column 207 of the distillation column, the main cooler 208 of the distillation column, and the main heat exchanger 205.

[0068] like Figure 2 As shown, according to an embodiment of the present invention, the cold energy storage system includes a high-temperature heat exchanger A201, a low-temperature heat exchanger A202, and two propane storage tanks A203.

[0069] The high-temperature heat exchanger A201 has three high-temperature heat exchanger fluid heat exchange channels, namely the first high-temperature heat exchanger fluid heat exchange channel G1, the second high-temperature heat exchanger fluid heat exchange channel G2, and the third high-temperature heat exchanger fluid heat exchange channel G3.

[0070] The low-temperature heat exchanger A202 has four low-temperature heat exchanger fluid heat exchange channels, namely the first low-temperature heat exchanger fluid heat exchange channel D1, the second low-temperature heat exchanger fluid heat exchange channel D2, the third low-temperature heat exchanger fluid heat exchange channel D3 and the fourth low-temperature heat exchanger fluid heat exchange channel D4.

[0071] The energy release system includes a blower A204, a second cooler A205, and a second air compressor A206. One end of the second cooler A205 is connected to the blower A204, and the other end is connected to the precooling system.

[0072] like Figure 2 As shown, according to an embodiment of the present invention, one end of the first high-temperature heat exchanger fluid heat exchange channel G1 of the high-temperature heat exchanger A201 is connected to the first cooler 203, and the other end is connected to the expander 204.

[0073] The first high-temperature heat exchanger fluid heat exchange channel G1 of the high-temperature heat exchanger A201 is a forward heat exchange channel, and the heat exchange fluid is medium-pressure air.

[0074] One end of the second high-temperature heat exchanger fluid heat exchange channel G2 of the high-temperature heat exchanger A201 is connected to the purification system, and the other end is connected to the second low-temperature heat exchanger fluid heat exchange channel D2 of the low-temperature heat exchanger A202.

[0075] The second high-temperature heat exchanger fluid heat exchange channel G2 of the high-temperature heat exchanger A201 is connected to one end of the purification system and also to the first air compressor 201.

[0076] The second high-temperature heat exchanger fluid heat exchange channel G2 of the high-temperature heat exchanger A201 is a forward and counter-flow heat exchange channel, and the heat exchange fluid is low-pressure air.

[0077] One end of the third high-temperature heat exchanger fluid heat exchange channel G3 of the high-temperature heat exchanger A201 is connected to the precooling system, and the other end is connected to the third low-temperature heat exchanger fluid heat exchange channel D3 of the low-temperature heat exchanger A202.

[0078] The third high-temperature heat exchanger fluid heat exchange channel G3 of the high-temperature heat exchanger A201 is a counter-current heat exchange channel, and the heat exchange fluid is sludge nitrogen.

[0079] like Figure 2 As shown, according to an embodiment of the present invention, the first low-temperature heat exchanger fluid heat exchange channel D1 of the low-temperature heat exchanger A202 is connected to the distillation system.

[0080] Specifically, the main heat exchanger 205 is connected to the lower column 207 of the distillation column in the distillation system. One end of the first low-temperature heat exchanger fluid heat exchange channel D1 of the low-temperature heat exchanger A202 is connected to the second air compressor A206, and the other end is connected to the pipeline between the main heat exchanger 205 and the lower column 207 of the distillation column in the distillation system.

[0081] The first low-temperature heat exchanger fluid heat exchange channel D1 of the low-temperature heat exchanger A202 is a forward and counter-flow heat exchange channel, and the heat exchange fluid is medium-pressure air.

[0082] The second low-temperature heat exchanger fluid heat exchange channel D2 of the low-temperature heat exchanger A202 is connected to the expander, the distillation system, and the second air compressor A206.

[0083] Specifically, the second cryogenic heat exchanger fluid heat exchange channel D2 of cryogenic heat exchanger A202 connects the expander 204 to the first subcooler 206 of the distillation system. The second air compressor A206 is connected to the first cryogenic heat exchanger fluid heat exchange channel D1 of cryogenic heat exchanger A202.

[0084] The second low-temperature heat exchanger fluid heat exchange channel D2 of the low-temperature heat exchanger A202 is a forward and counter-current heat exchange channel, and the heat exchange fluid is low-pressure air.

[0085] The third cryogenic heat exchanger fluid heat exchange channel D3 of cryogenic heat exchanger A202 connects the main heat exchanger 205 to the nitrogen-laden pipe between the distillation system and the main heat exchanger 205. Specifically, the third cryogenic heat exchanger fluid heat exchange channel D3 of cryogenic heat exchanger A202 connects the main heat exchanger 205 to the nitrogen-laden pipe between the main heat exchanger 205 and the second subcooler 210 of the distillation system.

[0086] The third low-temperature heat exchanger fluid heat exchange channel D3 of the low-temperature heat exchanger A202 is a counter-current heat exchange channel, and the heat exchange fluid is sludge nitrogen.

[0087] The fourth cryogenic heat exchanger fluid heat exchange channel D4 of cryogenic heat exchanger A202 is connected to two propane storage tanks A203 at both ends. The two propane storage tanks A203 store high-temperature propane and low-temperature propane, respectively. In some embodiments, the cold storage medium of the propane storage tank A203 can be a single or mixed fluid such as methanol, ethanol, methane, propane, butane, or carbon dioxide, or a solid particle bed cold storage can be used.

[0088] The fourth cryogenic heat exchanger fluid heat exchange channel D4 of cryogenic heat exchanger A202 is a forward and counter-current heat exchange channel, and the heat exchange fluid is propane.

[0089] like Figure 2 As shown in the embodiment of the present invention, an energy storage method for an energy storage system coupled to an external compressed air separation system is provided. During off-peak electricity hours at night, the energy storage system coupled to an external compressed air separation system provided by the present invention is used for energy storage. Figure 2 The thick solid line represents the energy storage process.

[0090] Specifically, during off-peak electricity hours at night, energy storage is performed using an energy storage system coupled to an external compressed air separation system provided by this invention, including the following methods:

[0091] The precooling system, purification system, and air compression / expansion system (first air compressor 201, booster compressor 202, first cooler 203, and expander 204) of the external compressed air separation system experience increased operating loads, while the main heat exchanger 205 and the distillation system (first subcooler 206, lower column of distillation column 207, main cooler of distillation column 208, upper column of distillation column 208, and second subcooler 210) maintain unchanged operating conditions.

[0092] In this embodiment, the external compression air separation system is a conventional external compression air separation process with a capacity of 40,000 Nm3 / h. The booster compressor 202 is subjected to an increased load, i.e., the compressed air flow rate is increased. The increased airflow is drawn out from in front of the main heat exchanger 205 and enters the added cold energy storage system. The operating conditions of the main heat exchanger 205 and the distillation system are not affected.

[0093] The first air flow (medium-pressure airflow) Q5 is drawn from the first cooler 203 and enters the first high-temperature heat exchanger fluid heat exchange channel G1 of the high-temperature heat exchanger A201 for cooling. Then it is introduced into the expander 204 to obtain low-temperature air.

[0094] Low-temperature air enters the second low-temperature heat exchanger fluid heat exchange channel D2 of the low-temperature heat exchanger A202 and exchanges heat with the propane stream in the fourth low-temperature heat exchanger fluid heat exchange channel D4 of the low-temperature heat exchanger A202, storing the low-temperature cooling capacity (surplus cooling capacity) of the low-temperature air in two propane storage tanks A203.

[0095] After passing through the second low-temperature heat exchanger fluid heat exchange channel D2 of the low-temperature heat exchanger A202, the low-temperature air enters the second high-temperature heat exchanger fluid heat exchange channel G2 of the high-temperature heat exchanger A201, where it exchanges heat with the first air flow rate Q5 in the first high-temperature heat exchanger fluid heat exchange channel G1 of the high-temperature heat exchanger A201, thereby cooling the first air flow rate Q5 in the first high-temperature heat exchanger fluid heat exchange channel G1 of the high-temperature heat exchanger A201.

[0096] The cooled air after heat exchange returns to the first air compressor 201 for compression, forming a medium-pressure airflow again.

[0097] In the energy storage process of this invention, the added cold energy storage system uses isentropic cyclic cooling and stores the cold energy in two propane storage tanks A203.

[0098] During the energy storage process of this invention, the operating load of the air compression / expansion system increases, the first gas flow rate Q5 isentropic expansion cycle cooling, and the cold energy in the low temperature air after the expander 204 is stored by the low temperature heat exchanger A202 and the propane storage tank A203.

[0099] like Figure 2 As shown in the embodiment of the present invention, an energy release method for an energy storage system coupled to an external compressed air separation system is provided. During peak daytime electricity periods, the energy storage system coupled to an external compressed air separation system provided by the present invention is used for energy release. Figure 2 The thick dashed line represents the energy release process.

[0100] Specifically, during peak daytime electricity periods, energy is released using an energy storage system coupled to an external compressed air separation system provided by this invention, including the following methods:

[0101] The air compression / expansion system (first air compressor 201, booster compressor 202, first cooler 203 and expander 204) of the external compressed air separation system operates at reduced load, the main heat exchanger 205 operates at reduced load, and the precooling system, purification system and distillation system (first subcooler 206, lower column of distillation column 207, main cooler of distillation column 208, upper column of distillation column 208 and second subcooler 210) maintain unchanged operating conditions.

[0102] A second gas flow rate Q6 is drawn from the external environment and compressed by blower A204. The second gas flow rate Q6 is compressed by blower A204 to the same pressure as the upper column 209 of the distillation column in the distillation system.

[0103] After passing through blower A204, the second gas flow rate Q6 passes through the second cooler A205, the precooling system, and the purification system, and then sequentially enters the second high-temperature heat exchanger fluid heat exchange channel G2 of high-temperature heat exchanger A201 and the second low-temperature heat exchanger fluid heat exchange channel D2 of low-temperature heat exchanger A202 for cooling.

[0104] After cooling, the second gas flow rate Q6 is split into two streams and enters the distillation system. One stream is as follows: the second gas flow rate Q6 after cooling enters the pipeline between the expander 204 and the first subcooler 206 of the distillation system, and then enters the upper column 209 of the distillation column of the distillation system through the first subcooler 206.

[0105] The other route is as follows: the second gas flow rate Q6, after being cooled by the fluid heat exchange channel D2 of the second low-temperature heat exchanger A202, enters the second air compressor A206 for compression. The second gas flow rate Q6 is compressed by the second air compressor A206 to the same pressure as the lower column 207 of the distillation column in the distillation system.

[0106] The second gas flow rate Q6, compressed by the second air compressor A206, enters the first low-temperature heat exchanger fluid heat exchange channel D1 of the low-temperature heat exchanger A202 for cooling. After cooling, the second gas flow rate Q6 passes through the pipeline between the main heat exchanger 205 and the lower column 207 of the distillation column of the distillation system, and enters the lower column 207 of the distillation column of the distillation system.

[0107] During the energy release process, the air flow of the first air compressor 201 and the booster compressor 202 decreases, the air flow entering the main heat exchanger 205 decreases, and the main heat exchanger 205 operates at a reduced load.

[0108] After the main heat exchanger 205 is operated at reduced load, the excess amount of polluted nitrogen in the polluted nitrogen pipeline between the main heat exchanger 205 and the distillation system (the polluted nitrogen pipeline between the main heat exchanger 205 and the second subcooler 210 of the distillation system) enters sequentially into the third low-temperature heat exchanger fluid heat exchange channel D3 of the low-temperature heat exchanger A202 and the third high-temperature heat exchanger fluid heat exchange channel G3 of the high-temperature heat exchanger A201 to cool the second gas flow rate Q6 in the second low-temperature heat exchanger fluid heat exchange channel D2 of the low-temperature heat exchanger A202, the second gas flow rate Q6 in the first low-temperature heat exchanger fluid heat exchange channel D1 of the low-temperature heat exchanger A202, and the second gas flow rate Q6 in the second high-temperature heat exchanger fluid heat exchange channel G2 of the high-temperature heat exchanger A201.

[0109] Meanwhile, the propane stream in the fourth low-temperature heat exchanger fluid heat exchange channel D4 of the low-temperature heat exchanger A202 cools the second gas flow rate Q6 entering the second low-temperature heat exchanger fluid heat exchange channel D2 of the low-temperature heat exchanger A202, as well as the second gas flow rate Q6 in the first low-temperature heat exchanger fluid heat exchange channel D1 of the low-temperature heat exchanger A202.

[0110] The excess nitrogen waste enters the precooling system after passing through the third high-temperature heat exchanger fluid heat exchange channel G3 of the high-temperature heat exchanger A201.

[0111] During the energy release process of this invention, the operating load of the air compression / expansion system is reduced, and a second gas flow rate Q6 is introduced from the environment. After being cooled by the refluxed waste nitrogen and the cold energy of the propane storage tank A203, the gas directly enters the upper column 209 of the distillation column or is pressurized by the second air compressor A206 and then enters the lower column 207 of the distillation column. After the second gas flow rate Q6 is replenished, the gas flow rate and temperature entering the upper column 209 and the lower column 207 of the distillation column remain unchanged.

[0112] In some preferred embodiments, the second gas flow rate Q6 preferentially enters the upper column 209 of the distillation column, reducing the load on the booster compressor 202.

[0113] Through thermodynamic calculations, this invention shows that during the energy release process, the stored cold energy is used to supplement the reduced gas volume of the booster A202 (Rachman inlet gas of the upper column 209 of the distillation column), which can achieve a higher energy storage efficiency, with an electrical energy efficiency of 80%~90%; the stored cold energy is used to supplement the lower column 207 of the distillation column, with an efficiency of 60~75%.

[0114] The following points need to be explained:

[0115] (1) The accompanying drawings of the embodiments of the present invention only involve the structures involved in the embodiments of the present invention. Other structures can refer to the general design.

[0116] (2) For clarity, the thickness of layers or regions is enlarged or reduced in the drawings used to describe embodiments of the invention, i.e., these drawings are not drawn to scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being “above” or “below” another element, the element may be “directly” located “above” or “below” the other element or there may be intermediate elements.

[0117] (3) Where there is no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0118] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An energy storage system coupled to an external compressed air separation system, characterized in that, The energy storage system includes an external compressed air separation system, and a cold energy storage system and an energy release system added to the external compressed air separation system; The external compression air separation system includes a precooling system, a purification system, an air compression / expansion system, a main heat exchanger, and a distillation system; The air compression / expansion system includes a first air compressor, a booster compressor, a first cooler, and an expander; the first air compressor is connected to the precooling system, the precooling system is connected to the purification system, the purification system is connected to the booster compressor, and the booster compressor is connected to the first cooler; The first cooler is connected to the main heat exchanger; the main heat exchanger is connected to the distillation system and the expander; the expander is connected to the distillation system. The cold energy storage system includes a high-temperature heat exchanger, a low-temperature heat exchanger, and two propane storage tanks; the high-temperature heat exchanger has three high-temperature heat exchanger fluid heat exchange channels; and the low-temperature heat exchanger has four low-temperature heat exchanger fluid heat exchange channels. The energy release system includes a blower, a second cooler, and a second air compressor; one end of the second cooler is connected to the blower, and the other end is connected to the precooling system. The first high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger is connected to the first cooler at one end and to the expander at the other end. One end of the second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger is connected to the purification system, and the other end is connected to the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger. The second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger is connected to one end of the purification system and also to the first air compressor; One end of the third high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger is connected to the precooling system, and the other end is connected to the third low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger. The first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger is connected to the distillation system. The second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger is connected to the expander, the distillation system, and the second air compressor; the second air compressor is connected to the first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger. The third low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger is connected to the nitrogen-sludge pipeline between the main heat exchanger and the distillation system. The two ends of the fourth low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger are respectively connected to the two propane storage tanks.

2. The energy storage system according to claim 1, characterized in that, The distillation system includes a first subcooler, a lower column of the distillation column, a main cooler of the distillation column, an upper column of the distillation column, and a second subcooler. One end of the first subcooler is connected to the expander and the main heat exchanger; the other end of the first subcooler is connected to the upper column of the distillation column and the main cooler of the distillation column.

3. The energy storage system according to claim 2, characterized in that, The second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger connects the expander and the first subcooler of the distillation system.

4. The energy storage system according to claim 2, characterized in that, The main heat exchanger is connected to the lower column of the distillation column; The first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger is a pipeline connecting the main heat exchanger and the lower column of the distillation column of the distillation system.

5. The energy storage system according to claim 1, characterized in that, The propane storage tank of the cold energy storage system uses a single or mixed fluid of methanol, ethanol, methane, propane, butane, and carbon dioxide as the cold storage medium, or adopts solid particle bed cold storage.

6. An energy storage method for an energy storage system coupled with an external compressed air separation system, characterized in that, During off-peak electricity periods, energy storage is performed using the energy storage system described in any one of claims 1 to 5, comprising the following methods: The precooling system, purification system and air compression / expansion system of the external compression air separation system will increase their operating load, while the main heat exchanger and distillation system will maintain their operating conditions. The first air flow rate is drawn from the first cooler and enters the first high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger for cooling. Then it is introduced into the expander to obtain low-temperature air. Low-temperature air enters the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger and exchanges heat with the propane stream in the fourth low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, storing the low-temperature coldness of the low-temperature air in two propane storage tanks. After passing through the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, the low-temperature air enters the second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger, where it exchanges heat with the first air flow in the first high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger. The low-temperature air after heat exchange returns to the first air compressor for compression.

7. A method for releasing energy from an energy storage system coupled with an external compressed air separation system, characterized in that, During peak power periods, energy release is performed using the energy storage system described in any one of claims 1 to 5, comprising the following methods: The air compression / expansion system of the external compression air separation system operates at a reduced load, the main heat exchanger operates at a reduced load, and the precooling system, purification system and distillation system maintain their operating conditions unchanged. A second gas flow is drawn from the external environment, compressed by a blower, and then passes through a second cooler, a precooling system, and a purification system. It then enters the second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger and the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger for cooling. After cooling, the second gas flow enters the upper column of the distillation column of the distillation system. After the main heat exchanger is operated at reduced load, the excess amount of polluted nitrogen in the polluted nitrogen pipeline between the main heat exchanger and the distillation system enters the third low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger and the third high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger in sequence, cooling the second gas flow rate in the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, the second gas flow rate in the first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, and the second gas flow rate in the second high-temperature heat exchanger fluid heat exchange channel of the high-temperature heat exchanger. The excess nitrogen waste enters the precooling system after passing through the fluid heat exchange channel of the third high-temperature heat exchanger of the high-temperature heat exchanger.

8. The energy release method according to claim 7, characterized in that, The second gas flow, cooled by the fluid heat exchange channel of the second low-temperature heat exchanger, enters the second air compressor for compression. The second air flow after compression by the second air compressor enters the fluid heat exchange channel of the first low-temperature heat exchanger for cooling. After cooling, the second gas flow rate enters the lower column of the distillation column of the distillation system.

9. The energy release method according to claim 7, characterized in that, The propane stream in the fourth low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger cools the second gas flow rate entering the second low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger, as well as the second gas flow rate in the first low-temperature heat exchanger fluid heat exchange channel of the low-temperature heat exchanger.

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