CN118274590A - Hydrogen production and direct air carbon capture system and method by coupling compressed air energy storage - Google Patents

Abstract

The invention discloses a hydrogen production and direct air carbon trapping system and method by coupling compressed air energy storage, and belongs to the technical field of carbon trapping technology and energy storage. The system comprises a compressed air energy storage system, an electrolytic water system and a direct air carbon capture system. The water electrolysis system and the direct air carbon capture system share the same water tank, and exhaust waste heat generated when the compressed air energy storage system expands and releases energy is used for heating the water tank, so that the hydrogen production efficiency of the water electrolysis system is improved, and the desorption efficiency of the direct air carbon capture system is improved; the cooled exhaust gas is supplied to a direct air carbon capture system, so that the energy consumption of the air blower is reduced; the low-grade heat energy in the low-temperature heat storage tank of the compressed air energy storage system can be used for regenerating a drying device in the direct air carbon capture system, so that the regeneration heat consumption is reduced. The system and the method realize flexible regulation of peak-valley electricity of the power grid and further realize green hydrogen production and carbon capture through energy cascade utilization.

Description

A system and method for hydrogen production and direct air carbon capture coupled with compressed air energy storage

Technical Field

The present invention belongs to the field of carbon capture technology and energy storage technology, and in particular relates to a hydrogen production and direct air carbon capture system and method coupled with compressed air energy storage.

Background technique

Global climate change is becoming increasingly significant, and extreme weather events are frequent. Excessive emissions of greenhouse gases are one of the main causes, and innovative solutions are urgently needed to deal with it. Carbon dioxide is the main greenhouse gas emitted by human activities, and it is urgent to reduce the concentration of carbon dioxide in the atmosphere. Direct air carbon capture technology, as a negative carbon emission technology, can directly capture carbon dioxide from the atmosphere, achieve negative carbon emissions, and provide key support for climate change mitigation. As one of the two major schools of direct air carbon capture technology, the variable humidity adsorption method captures carbon dioxide in the air through the difference in adsorption capacity of variable humidity materials at different humidity levels, adsorbing carbon dioxide at low humidity and releasing carbon dioxide at high humidity. Compared with the traditional temperature swing adsorption method, the variable humidity adsorption method has lower regeneration heat consumption and can tolerate higher inlet moisture content, but because the desorption process mainly relies on water mist spraying, and the dry adsorption process relies on fan drying, the fan power consumption and desorption water consumption remain high.

On the other hand, with the large-scale application of renewable energy such as wind and solar energy, the power system faces challenges due to the instability and unpredictability of these energy sources. When wind or sunshine conditions fluctuate, the power grid may face insufficient or excessive energy supply, which will affect the stability of the power system. The compressed air energy storage system uses electricity to compress and store air when power demand is low, and then releases the compressed air during peak periods to drive the generator through the expander to generate electricity. This system has high efficiency, relatively low environmental impact and long life, making it an ideal choice for solving the volatility of the power system. The exhaust of the expander of the compressed air energy storage system still has a certain grade of heat energy and pressure when releasing energy, which is difficult to be used by the system itself and is wasted. In addition to the compressed air energy storage system, water electrolysis to produce hydrogen is also a green and clean energy storage technology, but this technology requires a lot of electricity to support its operation, and the cost is much higher than the traditional hydrogen production method. The water used for electrolysis can be preheated to increase the reaction rate and increase the electrolysis efficiency, improving the technical economy.

In summary, compressed air energy storage technology has the potential for waste heat and waste pressure, while direct air carbon capture technology using humidity swing adsorption has problems such as large air volume demand, high fan power consumption, and high water consumption, and water electrolysis hydrogen production technology has the need to preheat the raw water to improve the technical economy. In terms of waste heat and waste pressure utilization and water resource recycling, these three technologies have great coupling potential.

Summary of the invention

In view of the coupling potential of the above three technologies in terms of waste heat and waste pressure utilization and water resource recycling, the present invention proposes a hydrogen production and direct air carbon capture system and method coupled with compressed air energy storage. In the present invention, the water electrolysis hydrogen production system and the direct air carbon capture system by variable humidity adsorption share the same water tank. The direct air carbon capture system reduces the overall water consumption of the two systems by capturing moisture from the air and recycling desorption water and condensed water. The low-grade compression heat and exhaust waste heat in the compressed air energy storage system are also effectively utilized by the hydrogen production and direct air carbon capture systems.

The specific technical solutions adopted by the present invention are as follows:

In a first aspect, the present invention provides a hydrogen production and direct air carbon capture system coupled with compressed air energy storage, comprising a compressed air energy storage system, a water electrolysis system and a direct air carbon capture system;

The compressed air energy storage system comprises a low-temperature heat storage tank, a first liquid pump, a third valve, a high-temperature heat storage tank, a second liquid pump, a fifth valve, and a low-pressure compressor, a first heat exchanger, a high-pressure compressor, a second heat exchanger, a first valve, a compressed air storage tank, a second valve, a third heat exchanger, a high-pressure expander, a fourth heat exchanger, a low-pressure expander, and a generator connected in sequence; the outlet of the low-temperature heat storage tank is connected in sequence to the first liquid pump and the third valve, and then to the first heat exchanger and the second heat exchanger respectively, and the fluid flows out from the first heat exchanger and the second heat exchanger after heat exchange and enters the high-temperature heat storage tank; the outlet of the high-temperature heat storage tank is connected in sequence to the second liquid pump and the fifth valve, and then to the third heat exchanger and the fourth heat exchanger respectively, and the fluid flows out from the third heat exchanger and the fourth heat exchanger after heat exchange and enters the low-temperature heat storage tank; the exhaust port of the low-pressure expander is connected to the hot side of the fifth heat exchanger;

The water electrolysis system comprises a water electrolysis device, a sixth valve, a hydrogen storage tank, a seventh valve, an oxygen storage tank, a water tank, an eighth valve, a ninth valve, a fifth heat exchanger and a third liquid pump; the hydrogen production end of the water electrolysis device is connected to the hydrogen storage tank through the sixth valve, and the oxygen production end is connected to the oxygen storage tank through the seventh valve; the water tank is connected to the water electrolysis device through the eighth valve, and is connected to the ninth valve, the cold side of the fifth heat exchanger and the third liquid pump in sequence to form a loop;

The direct air carbon capture system includes a first condenser, an eleventh valve, a fourth liquid pump, a fifth liquid pump, a twelfth valve, a fourth valve, and a fan, a buffer device, a drying device, a tenth valve, a carbon dioxide adsorption device, a vacuum pump, a second condenser, a carbon dioxide compressor, a sixth heat exchanger, a gas-liquid separator, a thirteenth valve, and a liquid carbon dioxide storage tank connected in sequence; the drying device is also connected to the first condenser, the eleventh valve, the fourth liquid pump, and the water tank in sequence, the second condenser is also connected to the twelfth valve and the fourth liquid pump in sequence, the gas-liquid separator is also connected to the drying device and the buffer device in sequence, the fifth heat exchanger is connected to the buffer device, the carbon dioxide adsorption device is connected to the fourth liquid pump, the water tank is connected to the carbon dioxide adsorption device through the fifth liquid pump, and the low-temperature heat storage tank is connected to the first liquid pump, the fourth valve and the drying device in sequence to form a loop.

Preferably, the low-pressure stage compressor and the high-pressure stage compressor are driven by being connected to a power grid.

Preferably, the high-pressure stage expander and the low-pressure stage expander are both connected to a generator.

Preferably, the direct air carbon capture system comprises at least one dry adsorption system composed of a drying device, a tenth valve and a carbon dioxide adsorption device; if there are multiple dry adsorption systems, the dry adsorption systems are connected in parallel and have the same external connection method.

Preferably, the regeneration method of the carbon dioxide adsorbent material in the carbon dioxide adsorption device is humidification regeneration.

Preferably, chilled water is also introduced into the sixth heat exchanger to cool the high-temperature and high-pressure carbon dioxide gas at the outlet of the liquefied carbon dioxide compressor.

In a second aspect, the present invention provides an operating method of a hydrogen production and direct air carbon capture system using any coupled compressed air energy storage as described in the first aspect, as follows:

S1: When the grid energy is sufficient, the compressed air energy storage system performs the compression energy storage process, and the surplus power drives the low-pressure compressor and the high-pressure compressor to compress the air to obtain high-temperature and high-pressure air; the fluid stored in the low-temperature heat storage tank flows through the first heat exchanger and the second heat exchanger under the drive of the first liquid pump and cools the high-temperature and high-pressure air, and then returns to the high-temperature heat storage tank, and the low-temperature and high-pressure air cooled by the second heat exchanger is stored in the compressed air storage tank; the water electrolysis device works under surplus power, and the obtained hydrogen and oxygen are stored in the hydrogen storage tank and the oxygen storage tank respectively;

The direct air carbon capture system performs a continuous adsorption and desorption process as follows:

During the adsorption process, the surplus electricity drives the fan to deliver air, and the air is mixed with the low-temperature and high-carbon dioxide concentration gas recovered from the gas-liquid separator in the buffer device to increase the adsorption concentration, capture rate and adsorption capacity. The low-temperature and high-carbon dioxide concentration gas recovered from the gas-liquid separator is assisted in cooling by the heat exchange pipeline of the drying device before entering the buffer device to save cooling consumption. The mixed gas is dehumidified by the drying device and then enters the carbon dioxide adsorption device for carbon capture, and then is discharged into the atmosphere; during the desorption process, the water in the water tank is driven by the fifth liquid pump to enter the carbon dioxide adsorption device for spraying, and then is recovered to the water tank under the driving force of the fourth liquid pump. The high-concentration carbon dioxide desorbed from the carbon dioxide adsorption device is extracted by a vacuum pump to the second condenser to remove moisture; the condensed water generated by the second condenser is recovered to the water tank by the fourth liquid pump, and the generated dry gas is pressurized by the carbon dioxide compressor, and is cooled and liquefied by chilled water in the sixth heat exchanger, and enters the gas-liquid separator. The obtained liquid carbon dioxide is stored in the liquid carbon dioxide storage tank;

S2: When the grid energy is insufficient, the compressed air energy storage system performs the expansion and energy release process. The second valve opens, and the compressed air in the compressed air storage tank drives the high-pressure expander and the low-pressure expander to drive the generator to generate electricity. The fluid stored in the high-temperature heat storage tank enters the third heat exchanger and the fourth heat exchanger respectively under the drive of the second liquid pump to heat the gas before expansion, and then returns to the low-temperature heat storage tank; the exhaust of the low-pressure expander enters the fifth heat exchanger, and circulates and heats the water tank under the drive of the third liquid pump, thereby improving the electrolysis efficiency of the water electrolysis device and the desorption efficiency of the direct air carbon capture system; the water electrolysis device temporarily stops working in the case of power shortage, or uses the energy released by the compressed air energy storage system to maintain work;

The direct air carbon capture system performs a continuous adsorption and desorption process as follows:

During the adsorption process, the exhaust gas of the low-pressure expander cooled by the fifth heat exchanger is mixed with the high carbon dioxide concentration gas recovered from the gas-liquid separator in the buffer device, thereby increasing the adsorption concentration and saving the power of the fan; during the desorption process, the fluid in the low-temperature heat storage tank flows through the fourth valve through the drying device under the drive of the first liquid pump, and is heated and regenerated by the low-grade compression heat, and then returns to the low-temperature heat storage tank, further reducing the temperature in the low-temperature heat storage tank and enhancing the cooling effect of the first heat exchanger and the second heat exchanger on the high-temperature and high-pressure air; the low-temperature and high-carbon dioxide concentration gas recovered from the gas-liquid separator is auxiliary cooled by the heat exchange pipeline of the drying device before entering the buffer device to save cooling consumption , the mixed gas is dehumidified by the drying device and then enters the carbon dioxide adsorption device for carbon capture, and then is discharged into the atmosphere; during the desorption process, the water in the water tank is driven by the fifth liquid pump to enter the carbon dioxide adsorption device for spraying, and then is recovered to the water tank under the driving force of the fourth liquid pump, and the high-concentration carbon dioxide desorbed from the carbon dioxide adsorption device is pumped to the second condenser by a vacuum pump to remove moisture; the condensed water produced by the second condenser is recovered to the water tank by the fourth liquid pump, and the produced dry gas is pressurized by the carbon dioxide compressor, and is cooled and liquefied by chilled water in the sixth heat exchanger, and enters the gas-liquid separator, and the obtained liquid carbon dioxide is stored in the liquid carbon dioxide storage tank.

Compared with the prior art, the present invention has the following beneficial effects:

A) The present invention utilizes the low-grade compression heat in the low-temperature heat storage tank to assist the regeneration of the carbon capture and drying device, thereby saving regeneration energy consumption. Meanwhile, the further decrease in the temperature in the low-temperature heat storage tank can enhance the cooling effect of the compressed high-temperature and high-pressure air, increase the system pressure ratio, and ultimately improve the energy storage efficiency.

B) The present invention recycles desorption gas condensate from the drying device of the direct air carbon capture system, the spray water and desorption gas condensate from the carbon dioxide adsorption device, and shares a water tank with the water electrolysis hydrogen production system, thereby reducing the water consumption of the two systems.

C) The present invention recovers the exhaust waste heat of the compressed air energy storage system and uses it to heat the water tank, thereby improving the reaction rate and electrolysis efficiency of the water electrolysis hydrogen production system and the desorption speed and efficiency of the direct air carbon capture system, thereby reducing the energy consumption cost of the two systems and improving the system performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a system for coupling hydrogen production with compressed air energy storage and direct air carbon capture according to the present invention.

In the figure:

1-power grid; 2-low-pressure compressor; 3-first heat exchanger; 4-high-pressure compressor; 5-second heat exchanger; 6-first valve; 7-compressed air storage tank; 8-second valve; 9-low-temperature heat storage tank; 10-first liquid pump; 11-third valve; 12-fourth valve; 13-high-temperature heat storage tank; 14-second liquid pump; 15-fifth valve; 16-third heat exchanger; 17-high-pressure expander; 18-fourth heat exchanger; 19-low-pressure expander; 20-generator; 21-water electrolysis device; 22-sixth valve; 23-hydrogen storage tank; 24-seventh valve; 25-oxygen storage tank; 26-water tank; 27-eighth valve; 28-ninth valve; 29-fifth heat exchanger; 30-third liquid pump; 31-fan; 32-buffer device; 33-drying device; 34-tenth valve; 35-carbon dioxide adsorption device; 36-first condenser; 37-eleventh valve; 38-fourth liquid pump; 39-fifth liquid pump; 40-vacuum pump; 41-second condenser; 42-carbon dioxide compressor; 43-twelfth valve; 44-sixth heat exchanger; 45-gas-liquid separator; 46-twelfth valve; 47-liquid carbon dioxide storage tank.

Detailed ways

The present invention is further described and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflicting with each other.

In the description of the present invention, it is to be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or indirectly connected, that is, there are intermediate elements. On the contrary, when an element is said to be "directly" connected to another element, there are no intermediate elements.

In the description of the present invention, it should be understood that the terms "first", "second" ... "twelfth", etc. are only used for distinguishing description purposes, and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" ... "twelfth" may explicitly or implicitly include at least one of the features.

In the description of the present invention, it is necessary to understand that the expressions “high temperature” and “low temperature” in the components “low temperature heat storage tank 9” and “high temperature heat storage tank 13” are only used to distinguish the description purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the temperature limit of the indicated technical features.

In the description of the present invention, it is necessary to understand that the expressions "low pressure" and "high pressure" in the components "low-pressure stage compressor 2, high-pressure stage compressor 4, high-pressure stage expander 17, low-pressure stage expander 19" are only used to distinguish the description purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the pressure limitation of the indicated technical features.

As shown in Figure 1, a hydrogen production and direct air carbon capture system coupled with compressed air energy storage is provided by the present invention, and the system mainly includes a compressed air energy storage system, a water electrolysis system and a direct air carbon capture system. Among them, the water electrolysis system and the direct air carbon capture system share the same water tank, and the exhaust waste heat of the compressed air energy storage system during expansion and energy release is used to heat the water tank, thereby improving the hydrogen production efficiency of the water electrolysis system and improving the desorption efficiency of the direct air carbon capture system by the variable humidity adsorption method; the cooled exhaust gas is supplied to the direct air carbon capture system to reduce the energy consumption of the fan; the low-grade heat energy in the low-temperature heat storage tank of the compressed air energy storage system can be used for the regeneration of the drying device in the direct air carbon capture system, thereby reducing the regeneration heat consumption. The system and method of the present invention can realize the flexible regulation of peak and valley electricity in the power grid, and further realize green hydrogen production and carbon capture through the cascade utilization of energy.

The following will provide a detailed description of the components and connection methods of each system.

In the present invention, the compressed air energy storage system mainly includes a low-temperature heat storage tank 9, a first liquid pump 10, a third valve 11, a high-temperature heat storage tank 13, a second liquid pump 14, a fifth valve 15, a low-pressure stage compressor 2, a first heat exchanger 3, a high-pressure stage compressor 4, a second heat exchanger 5, a first valve 6, a compressed air storage tank 7, a second valve 8, a third heat exchanger 16, a high-pressure stage expander 17, a fourth heat exchanger 18, a low-pressure stage expander 19, and a generator 20.

Specifically, the low-pressure compressor 2, the first heat exchanger 3, the high-pressure compressor 4, the second heat exchanger 5, the first valve 6, the compressed air storage tank 7, the second valve 8, the third heat exchanger 16, the high-pressure expander 17, the fourth heat exchanger 18, the low-pressure expander 19, and the generator 20 are connected in sequence through pipelines; wherein the low-pressure compressor 2, the first heat exchanger 3, the high-pressure compressor 4, and the second heat exchanger 5 connected in sequence together constitute a multi-stage compression and cooling device, and the third heat exchanger 16, the high-pressure expander 17, the fourth heat exchanger 18, and the low-pressure expander 19 connected in sequence together constitute a multi-stage heating and expansion device. The outlet of the low-temperature heat storage tank 9 is connected in sequence to the first liquid pump 10 and the third valve 11, and the third valve 11 is then connected to the first heat exchanger 3 and the second heat exchanger 5 in the multi-stage compression and cooling device through pipelines, and the fluid flows out from the first heat exchanger 3 and the second heat exchanger 5 after heat exchange and enters the high-temperature heat storage tank 13. The outlet of the high-temperature heat storage tank 13 is connected to the second liquid pump 14 and the fifth valve 15 in sequence, and then to the third heat exchanger 16 and the fourth heat exchanger 18 respectively. After heat exchange, the fluid flows out of the third heat exchanger 16 and the fourth heat exchanger 18 and enters the low-temperature heat storage tank 9. The exhaust port of the low-pressure stage expander 19 is connected to the hot side of the fifth heat exchanger 29, and the fifth heat exchanger 29 is used to recover the low-grade heat energy of the exhaust gas of the low-pressure stage expander 19 to increase the temperature of the water tank 26.

In a preferred embodiment of the present invention, the low-pressure stage compressor 2 and the high-pressure stage compressor 4 are driven by being connected to the power grid 1 , and the high-pressure stage expander 17 and the low-pressure stage expander 19 are both connected to the generator 20 .

In the present invention, the water electrolysis system mainly includes a water electrolysis device 21, a sixth valve 22, a hydrogen storage tank 23, a seventh valve 24, an oxygen storage tank 25, a water tank 26, an eighth valve 27, a ninth valve 28, a fifth heat exchanger 29 and a third liquid pump 30.

Specifically, the water electrolysis device 21 includes a hydrogen production end for producing hydrogen and an oxygen production end for producing oxygen, wherein the hydrogen production end is connected to the hydrogen storage tank 23 through the sixth valve 22, and the oxygen production end is connected to the oxygen storage tank 25 through the seventh valve 24. The water tank 26 is connected to the water electrolysis device 21 through the eighth valve 27, and is connected to the ninth valve 28, the cold side of the fifth heat exchanger 29, and the third liquid pump 30 in sequence to form a loop.

In the present invention, the direct air carbon capture system includes a first condenser 36, an eleventh valve 37, a fourth liquid pump 38, a fifth liquid pump 39, a twelfth valve 43, a fourth valve 12, a fan 31, a buffer device 32, a drying device 33, a tenth valve 34, a carbon dioxide adsorption device 35, a vacuum pump 40, a second condenser 41, a carbon dioxide compressor 42, a sixth heat exchanger 44, a gas-liquid separator 45, a thirteenth valve 46, and a liquid carbon dioxide storage tank 47.

Specifically, the fan 31, the buffer device 32, the drying device 33, the tenth valve 34, the carbon dioxide adsorption device 35, the vacuum pump 40, the second condenser 41, the carbon dioxide compressor 42, the sixth heat exchanger 44, the gas-liquid separator 45, the thirteenth valve 46, and the liquid carbon dioxide storage tank 47 are sequentially connected through pipelines. In addition, when the drying device 33 is regenerated, it is also connected to the first condenser 36, the eleventh valve 37, the fourth liquid pump 38, and the water tank 26 in sequence, the second condenser 41 is also connected to the twelfth valve 43 and the fourth liquid pump 38 in sequence, the gas-liquid separator 45 is also connected to the drying device 33 and the buffer device 32 in sequence, the fifth heat exchanger 29 is connected to the buffer device 32, the carbon dioxide adsorption device 35 is connected to the fourth liquid pump 38, the water tank 26 is connected to the carbon dioxide adsorption device 35 through the fifth liquid pump 39, and the low-temperature heat storage tank 9 is connected to the first liquid pump 10, the fourth valve 12 and the drying device 33 in sequence to form a loop. The low-temperature heat storage tank 9 is connected to the drying device 33, and the unused low-grade compression heat provides heat for the regeneration of the desiccant.

In actual use, the unliquefied low-temperature carbon dioxide gas in the gas-liquid separator 45 is used to cool the drying device 33 and then recycled into the buffer device 32. The water vapor regenerated by the drying device 33 is condensed in the first condenser 36, and the water vapor in the desorbed gas of the carbon dioxide adsorption device 35 is condensed in the second condenser 40, and both condensed waters are finally recycled into the water tank 26. The water tank 26 provides water sources for the electrolytic water system and the direct air carbon capture system at the same time. The exhaust gas of the expander 19 cooled by the fifth heat exchanger 29, the air introduced by the fan 31 and the heated exhaust gas of the gas-liquid separator 45 are mixed in the buffer device 32 as the gas source of the carbon capture system.

As a preferred embodiment of the present invention, there is at least one set of dry adsorption systems in the direct air carbon capture system, preferably at least two sets, so as to achieve continuous adsorption and desorption processes. The dry adsorption system is composed of a drying device 33, a tenth valve 34 and a carbon dioxide adsorption device 35. If there are multiple dry adsorption systems, the dry adsorption systems are connected in parallel and the connection method between each set of dry adsorption systems and the outside is the same.

As a preferred embodiment of the present invention, the regeneration method of the carbon dioxide adsorbent material in the carbon dioxide adsorption device 35 is humidification regeneration, which adsorbs carbon dioxide at low humidity and releases carbon dioxide at high humidity.

As a preferred embodiment of the present invention, chilled water is also introduced into the sixth heat exchanger 44 to cool the high-temperature and high-pressure carbon dioxide gas at the outlet of the liquefied carbon dioxide compressor.

The present invention further provides an operation method using the above-mentioned hydrogen production and direct air carbon capture system coupled with compressed air energy storage. The operation method mainly includes two operation modes, which are as follows:

S1 (Operation Mode 1): When the grid 1 has sufficient energy, the compressed air energy storage system performs the compression energy storage process, and the surplus power drives the low-pressure compressor 2 and the high-pressure compressor 4 to compress the air to obtain high-temperature and high-pressure air. The fluid stored in the low-temperature heat storage tank 9 flows through the first heat exchanger 3 and the second heat exchanger 5 under the drive of the first liquid pump 10 and cools the high-temperature and high-pressure air. The fluid then returns to the high-temperature heat storage tank 13, and the low-temperature and high-pressure air cooled by the second heat exchanger 5 is stored in the compressed air storage tank 7. The water electrolysis device 21 works under surplus power, and the obtained hydrogen and oxygen are stored in the hydrogen storage tank 23 and the oxygen storage tank 25 respectively.

The direct air carbon capture system performs a continuous adsorption and desorption process as follows:

During the adsorption process, the surplus power drives the fan 31 to deliver air, and the air is mixed with the low-temperature and high-carbon dioxide concentration gas recovered from the gas-liquid separator 45 in the buffer device 32 to increase the adsorption concentration, improve the capture rate and adsorption capacity. The low-temperature and high-carbon dioxide concentration gas recovered from the gas-liquid separator 45 is assisted in cooling by the heat exchange pipeline of the drying device 33 before entering the buffer device 32 to save cooling consumption. After being dehumidified by the drying device 33, the mixed gas enters the carbon dioxide adsorption device 35 for carbon capture and is then discharged into the atmosphere. During the desorption process, the water in the water tank 26 is driven by the fifth liquid pump 39 to enter the carbon dioxide adsorption device 35 for spraying, and then is recovered to the water tank 26 under the driving force of the fourth liquid pump 38. The high-concentration carbon dioxide desorbed from the carbon dioxide adsorption device 35 is extracted by the vacuum pump 40 to the second condenser 41 to remove moisture. The condensed water produced by the second condenser 41 is recovered to the water tank 26 through the fourth liquid pump 38, and the produced dry gas is pressurized by the carbon dioxide compressor 42, and is cooled and liquefied by chilled water in the sixth heat exchanger 44, and enters the gas-liquid separator 45. The obtained liquid carbon dioxide is stored in the liquid carbon dioxide storage tank 47.

S2 (Operation Mode 2): When the grid 1 is short of energy, the compressed air energy storage system performs the expansion and energy release process, the second valve 8 is opened, and the compressed air in the compressed air storage tank 7 drives the high-pressure expander 17 and the low-pressure expander 19 to drive the generator 20 to generate electricity. The fluid stored in the high-temperature heat storage tank 13 enters the third heat exchanger 16 and the fourth heat exchanger 18 respectively under the drive of the second liquid pump 14, and heats the gas before expansion, and then returns to the low-temperature heat storage tank 9. The exhaust of the low-pressure expander 19 enters the fifth heat exchanger 29, and the water tank 26 is circulated and heated under the drive of the third liquid pump 30, so as to improve the electrolysis efficiency of the water electrolysis device 21 and the desorption efficiency of the direct air carbon capture system. The water electrolysis device 21 temporarily stops working in the case of power shortage, or uses the energy release power of the compressed air energy storage system to maintain operation.

The direct air carbon capture system performs a continuous adsorption and desorption process as follows:

During the adsorption process, the exhaust gas of the low-pressure expansion machine 19 cooled by the fifth heat exchanger 29 is mixed with the high carbon dioxide concentration gas recovered from the gas-liquid separator 45 in the buffer device 32, increasing the adsorption concentration and saving the power of the fan. During the desorption process, the fluid in the low-temperature heat storage tank 9 flows through the drying device 33 through the fourth valve 12 driven by the first liquid pump 10, and is heated and regenerated by the low-grade compression heat, and then returns to the low-temperature heat storage tank 9, further reducing the temperature in the low-temperature heat storage tank 9, and enhancing the cooling effect of the first heat exchanger 3 and the second heat exchanger 5 on the high-temperature and high-pressure air. The low-temperature and high-carbon dioxide concentration gas recovered from the gas-liquid separator 45 is auxiliary cooled by the heat exchange pipeline of the drying device 33 before entering the buffer device 32 to save cooling consumption. After the mixed gas is dehumidified by the drying device 33, it enters the carbon dioxide adsorption device 35 for carbon capture, and then is discharged into the atmosphere. During the desorption process, the water in the water tank 26 is driven by the fifth liquid pump 39 to enter the carbon dioxide adsorption device 35 for spraying, and then is recovered to the water tank 26 under the driving force of the fourth liquid pump 38. The high-concentration carbon dioxide desorbed from the carbon dioxide adsorption device 35 is pumped to the second condenser 41 by the vacuum pump 40 to remove water. The condensed water produced by the second condenser 41 is recovered to the water tank 26 by the fourth liquid pump 38, and the produced dry gas is pressurized by the carbon dioxide compressor 42, and is cooled and liquefied by chilled water in the sixth heat exchanger 44, and enters the gas-liquid separator 45. The obtained liquid carbon dioxide is stored in the liquid carbon dioxide storage tank 47.

The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims (7)

1. A hydrogen production and direct air carbon capture system coupled with compressed air energy storage, characterized in that it includes a compressed air energy storage system, a water electrolysis system and a direct air carbon capture system; The compressed air energy storage system comprises a low-temperature heat storage tank (9), a first liquid pump (10), a third valve (11), a high-temperature heat storage tank (13), a second liquid pump (14), a fifth valve (15), and a low-pressure compressor (2), a first heat exchanger (3), a high-pressure compressor (4), a second heat exchanger (5), a first valve (6), a compressed air storage tank (7), a second valve (8), a third heat exchanger (16), a high-pressure expansion machine (17), a fourth heat exchanger (18), a low-pressure expansion machine (19), and a generator (20) connected in sequence; the outlet of the low-temperature heat storage tank (9) is connected in sequence to the first liquid pump (10) and the third valve (11), and then respectively connect the first heat exchanger (3) and the second heat exchanger (5), and the fluid flows out of the first heat exchanger (3) and the second heat exchanger (5) after heat exchange and enters the high-temperature heat storage tank (13); the outlet of the high-temperature heat storage tank (13) is connected to the second liquid pump (14) and the fifth valve (15) in sequence, and then respectively connects to the third heat exchanger (16) and the fourth heat exchanger (18), and the fluid flows out of the third heat exchanger (16) and the fourth heat exchanger (18) after heat exchange and enters the low-temperature heat storage tank (9); the exhaust port of the low-pressure stage expander (19) is connected to the hot side of the fifth heat exchanger (29); The water electrolysis system comprises a water electrolysis device (21), a sixth valve (22), a hydrogen storage tank (23), a seventh valve (24), an oxygen storage tank (25), a water tank (26), an eighth valve (27), a ninth valve (28), a fifth heat exchanger (29) and a third liquid pump (30); the hydrogen production end of the water electrolysis device (21) is connected to the hydrogen storage tank (23) through the sixth valve (22), and the oxygen production end is connected to the oxygen storage tank (25) through the seventh valve (24); the water tank (26) is connected to the water electrolysis device (21) through the eighth valve (27), and is sequentially connected to the ninth valve (28), the cold side of the fifth heat exchanger (29) and the third liquid pump (30) to form a loop; The direct air carbon capture system comprises a first condenser (36), an eleventh valve (37), a fourth liquid pump (38), a fifth liquid pump (39), a twelfth valve (43), a fourth valve (12), and a fan (31), a buffer device (32), a drying device (33), a tenth valve (34), a carbon dioxide adsorption device (35), a vacuum pump (40), a second condenser (41), a carbon dioxide compressor (42), a sixth heat exchanger (44), a gas-liquid separator (45), a thirteenth valve (46), and a liquid carbon dioxide storage tank (47) connected in sequence; the drying device (33) is also connected to the first condenser (36), The eleventh valve (37), the fourth liquid pump (38), and the water tank (26) are connected in sequence; the second condenser (41) is also connected in sequence with the twelfth valve (43) and the fourth liquid pump (38); the gas-liquid separator (45) is also connected in sequence with the drying device (33) and the buffer device (32); the fifth heat exchanger (29) is connected with the buffer device (32); the carbon dioxide adsorption device (35) is connected with the fourth liquid pump (38); the water tank (26) is connected with the carbon dioxide adsorption device (35) via the fifth liquid pump (39); and the low-temperature heat storage tank (9) is connected in sequence with the first liquid pump (10), the fourth valve (12), and the drying device (33) to form a loop. 2. A hydrogen production and direct air carbon capture system coupled with compressed air energy storage according to claim 1, characterized in that the low-pressure stage compressor (2) and the high-pressure stage compressor (4) are driven by being connected to a power grid (1). 3. A hydrogen production and direct air carbon capture system coupled with compressed air energy storage according to claim 1, characterized in that the high-pressure stage expander (17) and the low-pressure stage expander (19) are both connected to a generator (20). 4. A hydrogen production and direct air carbon capture system coupled with compressed air energy storage according to claim 1, characterized in that the direct air carbon capture system has at least one dry adsorption system composed of a drying device (33), a tenth valve (34) and a carbon dioxide adsorption device (35); if there are multiple dry adsorption systems, each dry adsorption system is connected in parallel and has the same external connection method. 5. A hydrogen production and direct air carbon capture system coupled with compressed air energy storage according to claim 1, characterized in that the regeneration method of the carbon dioxide adsorbent material in the carbon dioxide adsorption device (35) is humidification regeneration. 6. A hydrogen production and direct air carbon capture system coupled with compressed air energy storage according to claim 1, characterized in that chilled water is also introduced into the sixth heat exchanger (44) to cool the high-temperature and high-pressure carbon dioxide gas at the outlet of the liquefied carbon dioxide compressor (42). 7. A method for operating a hydrogen production and direct air carbon capture system using the coupled compressed air energy storage system according to any one of claims 1 to 6, characterized in that: S1: When the power grid (1) has sufficient energy, the compressed air energy storage system performs a compression energy storage process, and the surplus power drives the low-pressure compressor (2) and the high-pressure compressor (4) to compress the air to obtain high-temperature and high-pressure air; the fluid stored in the low-temperature heat storage tank (9) flows through the first heat exchanger (3) and the second heat exchanger (5) under the drive of the first liquid pump (10) and cools the high-temperature and high-pressure air, and then the fluid returns to the high-temperature heat storage tank (13), and the low-temperature and high-pressure air cooled by the second heat exchanger (5) is stored in the compressed air storage tank (7); the water electrolysis device (21) works under surplus power, and the obtained hydrogen and oxygen are stored in the hydrogen storage tank (23) and the oxygen storage tank (25) respectively; The direct air carbon capture system performs a continuous adsorption and desorption process as follows: During the adsorption process, the surplus power drives the fan (31) to deliver air, and the air is mixed with the low-temperature high-carbon dioxide concentration gas recovered from the gas-liquid separator (45) in the buffer device (32), thereby increasing the adsorption concentration, improving the capture rate and the adsorption capacity. The low-temperature high-carbon dioxide concentration gas recovered from the gas-liquid separator (45) is assisted in cooling by the heat exchange pipeline of the drying device (33) before entering the buffer device (32) to save cooling consumption. After being dehumidified by the drying device (33), the mixed gas enters the carbon dioxide adsorption device (35) for carbon capture, and is then discharged into the atmosphere. During the desorption process, the water in the water tank (26) is driven by the fifth liquid pump (39). The carbon dioxide adsorption device (35) is sprayed and then recovered to the water tank (26) under the driving force of the fourth liquid pump (38). The high-concentration carbon dioxide desorbed from the carbon dioxide adsorption device (35) is pumped to the second condenser (41) through the vacuum pump (40) to remove moisture; the condensed water produced by the second condenser (41) is recovered to the water tank (26) through the fourth liquid pump (38), and the generated dry gas is pressurized by the carbon dioxide compressor (42), and is cooled and liquefied by chilled water in the sixth heat exchanger (44), and enters the gas-liquid separator (45), and the obtained liquid carbon dioxide is stored in the liquid carbon dioxide storage tank (47); S2: When the power grid (1) is short of energy, the compressed air energy storage system performs an expansion and energy release process, the second valve (8) is opened, and the compressed air in the compressed air storage tank (7) drives the high-pressure expansion machine (17) and the low-pressure expansion machine (19) to drive the generator (20) to generate electricity. The fluid stored in the high-temperature heat storage tank (13) enters the third heat exchanger (16) and the fourth heat exchanger (18) respectively under the drive of the second liquid pump (14), and heats the gas before expansion, and then returns to the low-temperature heat storage tank (9); the exhaust of the low-pressure expansion machine (19) enters the fifth heat exchanger (29), and circulates and heats the water tank (26) under the drive of the third liquid pump (30), thereby improving the electrolysis efficiency of the water electrolysis device (21) and the desorption efficiency of the direct air carbon capture system; the water electrolysis device (21) temporarily stops working in the case of power shortage, or uses the energy released by the compressed air energy storage system to maintain operation; The direct air carbon capture system performs a continuous adsorption and desorption process as follows: During the adsorption process, the exhaust gas of the low-pressure expansion machine (19) cooled by the fifth heat exchanger (29) is mixed with the high carbon dioxide concentration gas recovered from the gas-liquid separator (45) in the buffer device (32), thereby increasing the adsorption concentration and saving the power of the fan; during the desorption process, the fluid in the low-temperature heat storage tank (9) flows through the fourth valve (12) through the drying device (33) under the drive of the first liquid pump (10), and is heated and regenerated by using the low-grade compression heat, and then returns to the low-temperature heat storage tank (9), further reducing the temperature in the low-temperature heat storage tank (9) and enhancing the cooling effect of the first heat exchanger (3) and the second heat exchanger (5) on the high-temperature and high-pressure air; the low-temperature and high-carbon dioxide concentration gas recovered from the gas-liquid separator (45) is auxiliary cooled by the heat exchange pipeline of the drying device (33) before entering the buffer device (32) to save cooling consumption, and the mixed gas passes through the After dehumidification in the drying device (33), the carbon dioxide is captured in the carbon dioxide adsorption device (35) and then discharged into the atmosphere. During the desorption process, the water in the water tank (26) is driven by the fifth liquid pump (39) to enter the carbon dioxide adsorption device (35) for spraying, and then is recovered to the water tank (26) under the driving force of the fourth liquid pump (38). The high-concentration carbon dioxide desorbed from the carbon dioxide adsorption device (35) is pumped into the second condenser (41) through the vacuum pump (40) to remove moisture. The condensed water generated by the second condenser (41) is recovered to the water tank (26) through the fourth liquid pump (38). The generated dry gas is pressurized by the carbon dioxide compressor (42), cooled and liquefied by chilled water in the sixth heat exchanger (44), and enters the gas-liquid separator (45). The obtained liquid carbon dioxide is stored in the liquid carbon dioxide storage tank (47).