Compressed air energy storage expansion side desalting system and application

Abstract

The invention relates to the technical field of compressed air energy storage, and discloses a compressed air energy storage expansion side desalting system and application, the compressed air energy storage expansion side desalting system is arranged on a salt cavern air reservoir pipeline on a compression energy storage expansion machine side, and the compressed air energy storage expansion side desalting system comprises a spraying subsystem, a separation subsystem and a recovery subsystem which are connected in sequence; the spraying subsystem at least comprises a storage tank, and a heating device used for adjusting the water temperature is arranged in the storage tank; the spraying subsystem sprays medium-temperature liquid into the pipeline and is used for dissolving salt particles discharged from the salt cavern gas reservoir to the pipeline; the separation subsystem comprises an axial flow separation device, salt drops are thrown to the pipe wall through centrifugal force generated by rotation, and separated pure air enters a compression energy storage expansion machine to do work. The spraying subsystem is combined with the separation subsystem, so that the gas-solid separation process with uncontrollable salt particle size and low efficiency is converted into efficient gas-liquid separation with controllable drop liquid particle size range, trace and small salt particles in high-pressure air can be effectively separated, the separation efficiency is improved, impurities entering subsequent equipment are reduced, and the service life of the equipment is prolonged.

Description

[0001] This invention relates to the field of compressed air energy storage technology, and more specifically to a system and application for removing salt particles and impurities on the expansion side of a compressed air energy storage system. Background Technology

[0002] Compressed air energy storage is a rapidly developing energy storage method in recent years. Its working principle is to use air as a medium, convert off-peak electricity into the pressure potential energy of air through a compressor, and store it in natural abandoned salt caverns. During peak electricity demand, the high-pressure air is released, heated, and then driven by an expander to generate electricity, converting the pressure potential energy back into electrical energy to make up for the grid gap.

[0003] The inner walls of natural abandoned salt caverns contain a large number of salt particles. During the expansion power generation process, when high-pressure air flows out of the salt cavern, it inevitably carries salt particles and impurities. According to calculations, the mass flow rate of salt on the expansion side of a certain project utilizing abandoned salt caverns can reach 0.33 g / s. These salts move downstream with the air and either impact or adhere to key components such as heat exchanger tubes, causing multiple corrosion effects such as impact physical damage and salt spray chemical corrosion, shortening the service life of equipment and increasing system safety hazards.

[0004] Existing desalination technologies are mostly used in the field of water treatment, such as electrolysis and high-temperature evaporation, which are mainly used for the separation of salts in solutions. They are difficult to apply directly to compressed air energy storage systems because the air in these systems is the working medium that enters the downstream expander, so the pressure loss of the high-pressure air must be minimized.

[0005] Because the air pressure stored in salt caverns is typically high, safety must be the primary consideration when designing a separation system under high-pressure conditions. Furthermore, the salt particles carried by the high-pressure air are quite small, resulting in a low distribution density within the pipes and a certain flow velocity. Relying on purely mechanical methods for collection and separation, such as wire mesh or separators, inevitably increases the pressure potential energy loss of the compressed air, reducing overall economic performance. Moreover, mechanical gas-solid separation devices have limited effectiveness in separating salt particles smaller than 10μm. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problem of separating trace and fine salt particles in high back pressure air, and to propose a system for removing salt particles and impurities on the expansion side of a compressed air energy storage system and its application.

[0007] To achieve the above objectives, as a first aspect, the technical solution adopted by the present invention is to provide a desalination system on the side of a compressed energy storage expander, which is installed on the salt cavern gas storage pipeline on the side of the compressed energy storage expander, including a spray subsystem, a separation subsystem, and a recovery subsystem connected in sequence; the spray subsystem includes at least one storage tank, and the storage tank is equipped with a heating device for regulating water temperature; the spray subsystem sprays a medium-temperature liquid into the pipeline to dissolve the salt particles discharged from the salt cavern gas storage into the pipeline; the separation subsystem includes an axial flow separation device, which uses the centrifugal force generated by rotation to throw the salt droplets to the pipe wall, separating pure air to enter the compressed energy storage expander to do work.

[0008] According to the present invention, it further includes a recovery subsystem connected downstream of the separation subsystem, wherein salt droplets adhering to the pipe wall at the separation point of the separation subsystem enter the recovery subsystem.

[0009] According to the present invention, the spraying subsystem further includes a low-pressure storage tank, a medium-pressure storage tank and a high-pressure storage tank connected in series, and a water pump and a control valve are provided between each storage tank; the heating device is installed in the high-pressure storage tank.

[0010] According to the present invention, the high-pressure storage tank outlet of the spray subsystem is further connected to a nozzle extending into the main pipeline at the end of the pipeline, spraying droplets with a particle size greater than 20 μm to form a water curtain, allowing salt particles to collide and dissolve with the water curtain to form salt-containing mist droplets.

[0011] According to the present invention, the outlet end of the separation subsystem is provided with a flow guiding device, the cross section of which is closer to the outlet end of the separation subsystem is smaller than the cross section further away from the outlet end of the separation subsystem.

[0012] According to the invention, the recovery subsystem further includes an external hydrophobic tank for collecting impurities, which is connected to a pipeline via a control valve.

[0013] As a second aspect, the present invention also provides an application of a desalination system on the side of a compression storage expander, comprising the following steps.

[0014] Clean water is injected into the spray subsystem and gradually pressurized and circulated to the high-pressure storage tank. The heater in the high-pressure storage tank regulates the temperature of the clean water.

[0015] The spray subsystem sprays droplets into the high-pressure air duct, forming a water curtain. The free salt comes into full contact with the water curtain, forming a salt mist, which is then carried by the airflow into the separation subsystem.

[0016] The salt spray airflow rotates through the axial flow separator, and the radial centrifugal force causes the salt droplets to adhere to the tube wall, separating out the pure air;

[0017] Salt droplets adhering to the pipe wall gradually move to the recovery subsystem under the action of airflow;

[0018] The connection between the recovery subsystem and the pipeline is disconnected, and the brine in the external condensate tank is discharged through a pressure reducing and condensate draining device.

[0019] The pressure of the water in the high-pressure storage tank is slightly higher than 1 to 5 bar, and the water temperature is ≤80℃.

[0020] After shutdown, the final state water is transferred to the low-pressure storage tank through the throttling device, and the water state is restored to ≤1MPa, 20~50℃.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention combines a spray subsystem with a separation subsystem, transforming the inefficient gas-solid separation process with uncontrollable salt particle size into a highly efficient gas-liquid separation with a controllable droplet particle size range. This effectively separates trace amounts of fine salt particles from high-pressure air, improving separation efficiency, reducing impurities entering subsequent equipment, and extending equipment lifespan.

[0023] The spray subsystem of this invention solves the problems of high pressure impact and thermal stress by pre-pressurizing and heating, thus ensuring safe and stable operation under high pressure conditions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the desalination system on the side of the compression energy storage expander of the present invention.

[0025] 10-Spraying subsystem, 11-Low-pressure storage tank, 12-Medium-pressure water storage tank, 13-High-pressure water storage tank, 14-Heater, 15-Nozzle, 20-Separation subsystem, 21-Axial flow separator, 22-Flow guiding device, 30-Recovery subsystem, 31-Drainage tank. Detailed Implementation

[0026] To make the content of this invention more apparent and understandable, the following detailed description is provided in conjunction with preferred embodiments and accompanying drawings.

[0027] like Figure 1As shown in the figure, this application provides a desalination system on the side of a compressed air storage expander, installed on the pipeline of a salt cavern gas storage tank on the side of the compressed air storage expander. It includes a spray subsystem 10, a separation subsystem 20, and a recovery subsystem 30 connected in sequence. By sequentially spraying, separating, and recovering, it eliminates salt particles in the air, improves air purity, reduces physical damage caused by salt particle impact, and mitigates multiple corrosion effects such as salt spray chemical corrosion, extending equipment lifespan and improving system safety performance. Specifically, the spray subsystem 10 sprays droplets of a specific particle size into a high-pressure airflow, causing salt particles to contact, aggregate, and dissolve with the droplets, forming a salt-containing mist. It includes a low-pressure tank 11, a medium-pressure tank 12, and a high-pressure tank 13 connected in series via pipelines, with water pumps and control valves installed between each tank. A heating device 14 is installed inside the high-pressure tank 13 to regulate the water temperature. The end of the spray subsystem 10 is connected to a nozzle 15 extending into the main pipeline, generating droplets with a specific particle size greater than 20 μm through spraying. In the spray subsystem 10, high-pressure water is atomized into droplets larger than 20 μm through nozzles 15, forming a water curtain. Salt particles collide with and dissolve in this water curtain, forming salt-containing mist droplets. The heating device 14 can be a submerged electric heater, a coil heat exchanger, or a jacketed heater.

[0028] The separation subsystem 20, connected downstream of the spray subsystem 10, is used to separate salt-containing droplets from the air. It includes an axial flow separator 21, which is compact and has low pressure loss. The axial flow separator 21 is preferably an axial flow separator blade structure, which is simple in structure and provides good centrifugal effect. After the gas-liquid mixture enters the separation subsystem 20, the axial flow separator blades rotate. Under centrifugal force, denser droplets are thrown towards the pipe wall and adhere to it. The separated clean air is then used by the expander or heat exchanger. A flow guide device 22 is provided at the outlet end of the separation subsystem 20. The cross-section near the outlet end of the separation subsystem 20 is smaller than the cross-section further away from the outlet end. This gradual narrowing of the cross-section allows salt particles and liquid to further adhere to the wall surface, ultimately forming a liquid film on the pipe wall, enhancing the impurity dissolution effect. The recovery subsystem 30, connected downstream of the separation subsystem 20, is used to collect and remove saline liquid. It includes a flow-guiding component and a recovery component (not shown) located on the inner wall of the pipe for collecting saline solution accumulated on the wall surface, and an external condensate tank connected to the pipe via a control valve. The recovery subsystem is the same as existing technology and will not be described in detail here. Liquid droplets adhering to the pipe wall are propelled by the airflow towards the recovery subsystem, and guided by the flow-guiding and recovery components to the external condensate tank 31 for temporary storage, facilitating later unified removal.

[0029] The working process of this invention is as follows:

[0030] The spray subsystem uses clean water as the medium. It is pressurized and circulated from a low-pressure tank to a medium-pressure tank, and then pressurized again from the medium-pressure tank to a high-pressure tank. A heater is installed in the high-pressure tank to regulate the water temperature and prevent excessive temperature differences with the air, which could lead to heat exchange between the media and disrupt the normal operation of the heat exchanger. Under pressure differential, the high-pressure water is atomized into droplets with a specific particle size >20μm through two nozzles, facilitating downstream separation. The sprayed droplets form a water curtain within the high-pressure air pipeline, within the spray zone. Free salt in the compressed air comes into full contact with the water droplets, aggregating to form large particles, which dissolve in the water droplets to form a salt mist, which is then carried by the airflow into the separation system.

[0031] When air containing salt spray flows through the axial flow separator blades, the medium rotates, generating radial centrifugal force. During this process, salt particles and droplets in the air move towards the pipe wall due to density differences and accumulate. As they pass through the guide device, the cross-section gradually narrows, causing the salt particles and liquid to adhere further to the wall surface, eventually forming a liquid film on the pipe wall. This intensifies the dissolution of impurities and enhances the separation effect.

[0032] After a salt solution film forms on the pipe wall, it possesses a certain degree of fluidity and gradually moves to the recovery subsystem under the action of airflow. During this process, the airflow rate needs to be controlled to prevent "secondary carryover," which would affect the separation efficiency. The collected salt solution is stored in an external hydrophobic tank and discharged after gradual depressurization controlled by a control valve.

[0033] The operation process of this invention:

[0034] Power-on steps:

[0035] 1. Before the gas storage facility is opened, clean water is circulated and pressurized sequentially through pumps and valves in the spray subsystem, and then heated in the final storage tank. The final water condition in this system should be: pressure slightly higher than the air pressure inside the gas storage facility (1–5 bar), and temperature moderate (≤80℃).

[0036] 2. Control the valves to introduce pressurized and heated clean water into the spray subsystem, forming a spray that covers the pipes;

[0037] 3. Ventilation and impurity removal: Open the gas storage valve to start ventilation. Control the valve opening and adjust the gas speed to ensure that the pressure loss and separation efficiency in the separation subsystem meet the requirements.

[0038] 4. Simultaneously open the control valve of the recovery subsystem to receive condensate.

[0039] Shutdown procedure: 1. Gradually close the gas storage valves until they are completely shut off, stopping the gas supply;

[0040] 2. As the air volume decreases, gradually close the water outlet valve of the spray subsystem, reduce the spray volume until it is closed; turn off the heater, and after cooling, transfer the final state water to the low-pressure storage tank through the throttling device, and restore the water state to ≤1MPa, 20~50℃;

[0041] 3. After 5 to 10 minutes, disconnect the recovery subsystem from the pipeline, and discharge the brine in the external condensate tank through the pressure reduction and condensate draining device.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the principles of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any equivalent changes, modifications, and evolutions made by those skilled in the art to the above embodiments based on the essential technology of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A desalination system on the side of a compression storage expander, characterized in that, The salt cavern gas storage pipeline, located on the side of the compressed energy storage expander, includes a spray subsystem, a separation subsystem, and a recovery subsystem connected in sequence. The spray subsystem includes at least one storage tank, which is equipped with a heating device for regulating water temperature. The spray subsystem sprays a medium-temperature liquid into the pipeline to dissolve the salt particles discharged from the salt cavern gas storage into the pipeline. The separation subsystem includes an axial flow separator, which uses the centrifugal force generated by rotation to throw the salt droplets onto the pipe wall, separating pure air that enters the compressed energy storage expander to do work.

2. The desalination system on the compressor-side of the energy storage expander as described in claim 1, characterized in that, It also includes a recovery subsystem, which is connected downstream of the separation subsystem. Salt droplets adhering to the pipe wall at the separation point of the separation subsystem enter the recovery subsystem.

3. The desalination system on the compressor-side of the energy storage expander as described in claim 1, characterized in that, The spraying subsystem includes a low-pressure tank, a medium-pressure tank, and a high-pressure tank connected in series, with water pumps and control valves installed between each tank; the heating device is installed inside the high-pressure tank.

4. The desalination system on the side of the compression storage expander as described in claim 3, characterized in that, The high-pressure storage tank outlet of the spray subsystem is connected to a nozzle at the end of the pipeline that extends into the main pipeline. The nozzle sprays droplets with a particle size greater than 20 μm to form a water curtain, which allows salt particles to collide with and dissolve to form salt mist droplets.

5. The desalination system on the compressor-side of the energy storage expander as described in claim 1, characterized in that, The outlet end of the separation subsystem is equipped with a flow guiding device, the cross section of which is closer to the outlet end of the separation subsystem is smaller than the cross section further away from the outlet end of the separation subsystem.

6. The desalination system on the side of the compression storage expander as described in claim 2, characterized in that, The recovery subsystem includes an external hydrophobic tank for collecting impurities, which is connected to a pipeline via a control valve.

7. The application of the desalination system on the side of the compression storage expander as described in any one of claims 1-6, characterized in that, Includes the following steps, Clean water is injected into the spray subsystem and gradually pressurized and circulated to the high-pressure storage tank. The heater in the high-pressure storage tank regulates the temperature of the clean water. The spray subsystem sprays droplets into the high-pressure air duct, forming a water curtain. The free salt comes into full contact with the water curtain, forming a salt mist, which is then carried by the airflow into the separation subsystem. The salt spray airflow rotates through the axial flow separator, and the radial centrifugal force causes the salt droplets to adhere to the tube wall, separating out the pure air; Salt droplets adhering to the pipe wall gradually move to the recovery subsystem under the action of airflow; The connection between the recovery subsystem and the pipeline is disconnected, and the brine in the external condensate tank is discharged through a pressure reducing and condensate draining device.

8. The application of the desalination system on the side of the compression storage expander as described in claim 7, characterized in that, The pressure of the water in the high-pressure storage tank is slightly higher than 1 to 5 bar, and the water temperature is ≤80℃.

9. The application of the desalination system on the side of the compression storage expander as described in claim 7, characterized in that, After shutdown, the final state water is transferred to the low-pressure storage tank through the throttling device, and the water state is restored to ≤1MPa, 20~50℃.

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