Low temperature storage tank breathing gas recovery system and method

Abstract

The application relates to a low-temperature storage tank breath gas recovery system and method. In the low-temperature storage tank breath gas recovery system, a low-temperature cold storage working medium storage tank is connected with a medium-temperature cold storage working medium storage tank and constitutes a storage tank top gas phase space, the storage tank top gas phase space is connected with a solid-phase cold storage device, the solid-phase cold storage device is connected with a buffer tank through a gas suction pipeline and a gas exhaust pipeline, and the gas suction pipeline and the gas exhaust pipeline are connected in parallel. In the low-temperature storage tank breath gas recovery system and method, the excess breath gas in the storage tank top gas phase space is buffered by the buffer tank, so that the pressure of the storage tank top gas phase space is relieved, the safety and stability of the storage tank top gas phase space are ensured, the breath gas can be controlled more safely and stably by the characteristics of the solid-phase cold storage device, the breath gas flow and the breath gas flow direction are not limited in the heat exchange process, that is, the influence of nitrogen dissolution on the breath gas buffering treatment does not need to be considered in the low-temperature storage tank breath gas recovery system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a low-temperature storage tank breathing gas recovery system and method based on solid-phase cold storage. BACKGROUND

[0002] Liquid air energy storage technology has the advantages of clean and low carbon, safety, long service life and the like, and is one of the most potential and competitive long-time energy storage technologies. Cold storage technology is the core of a liquid air energy storage system. According to different cold storage media, cold storage technology is specifically divided into liquid-phase cold storage, phase-change cold storage and solid-phase cold storage. A liquid air energy storage system based on liquid-phase cold storage has higher efficiency, however, during energy storage and release operation, as the liquid-phase cold storage medium enters and exits the cold storage medium storage tank, the pressure of the gas phase space at the top of the storage tank also changes, and when the pressure of the gas phase space at the top reaches the upper or lower limit of the design pressure of the storage tank, in order to ensure system safety and meet environmental protection requirements, the breathing gas needs to be recovered and treated.

[0003] However, the existing liquid air energy storage breathing gas recovery system generally has some defects, for example: the breathing gas recovery system connected to the top of the normal-pressure cold storage medium storage tank, as the allowable pressure fluctuation range of the normal-pressure storage tank is generally narrow, overpressure and negative pressure of the storage tank are prone to occur during the breathing gas recovery process; the breathing gas recovery system connected to the top of the high-pressure cold storage medium storage tank has the problem of high investment cost, and is only suitable for small-scale liquid air energy storage systems; and for large-scale liquid air energy storage systems, the temperature and pressure changing operation involved in the breathing gas treatment process is prone to cause problems such as increased cost of related equipment and waste of part of the cold energy.

[0004] More importantly, the existing liquid air energy storage system usually uses nitrogen as a cold storage working medium protection gas during actual operation, and thus the dissolution of nitrogen in the cold storage working medium is inevitable. However, the existing liquid air energy storage system is usually designed directly according to the condition of no dissolved nitrogen, while the dissolution of nitrogen in the cold storage working medium has a great influence on the gas quantity change and the gas flow direction of the breathing gas during actual operation. Therefore, for large-scale liquid air energy storage systems, the dissolution of nitrogen in the cold storage working medium still causes the problem that the breathing gas system heat exchanger device cannot be accurately designed. SUMMARY

[0005] The present application provides a low-temperature storage tank breathing gas recovery system and method to solve the problem that, for large-scale liquid air energy storage systems, the dissolution of nitrogen in the cold storage working medium causes the breathing gas system heat exchanger device to be difficult to accurately design.

[0006] The application provides a low-temperature storage tank breathing gas recovery system, comprising a low-temperature storage tank, a medium-temperature storage tank, a buffer tank and a solid-phase regenerator; the low-temperature storage tank is connected with the medium-temperature storage tank and forms a gas phase space at the top of the storage tank, the gas phase space at the top of the storage tank is connected with the solid-phase regenerator, the solid-phase regenerator is connected with the buffer tank through an inhale pipeline and an exhale pipeline, and the inhale pipeline and the exhale pipeline are arranged in parallel.

[0007] The low-temperature storage tank breathing gas recovery system further comprises a pressure reducing valve and a pressure gauge, the pressure reducing valve is arranged in series in the inhale pipeline, the pressure gauge is connected with the gas phase space at the top of the storage tank, and the pressure gauge is linked with the pressure reducing valve for linkage control.

[0008] The low-temperature storage tank breathing gas recovery system further comprises an exhaust treatment pipeline, the exhaust treatment pipeline is connected between the gas phase space at the top of the storage tank and the solid-phase regenerator; the exhaust treatment pipeline is provided with an emission control valve, and the pressure gauge is linked with the emission control valve for linkage control.

[0009] The low-temperature storage tank breathing gas recovery system further comprises an exhaust treatment pipeline, the exhaust treatment pipeline is connected between the gas phase space at the top of the storage tank and the solid-phase regenerator; the exhaust treatment pipeline is provided with an emission control valve, and the pressure gauge is linked with the emission control valve for linkage control.

[0010] The low-temperature storage tank breathing gas recovery system further comprises a compressor and an air cooler, the compressor and the air cooler are arranged in series in the exhale pipeline, and the compressor and the air cooler are sequentially connected between the solid-phase regenerator and the buffer tank.

[0011] The low-temperature storage tank breathing gas recovery system further comprises a compressor and an air cooler, the compressor and the air cooler are arranged in series in the exhale pipeline, and the compressor and the air cooler are sequentially connected between the solid-phase regenerator and the buffer tank.

[0012] The application further provides a low-temperature storage tank breathing gas recovery method, which is executed by using the low-temperature storage tank breathing gas recovery system, and comprises an exhale step and an inhale step.

[0013] The exhale step comprises the following steps: if the pressure of the gas phase space at the top of the storage tank reaches a predetermined upper limit value, the gas flow in the gas phase space at the top of the storage tank is released to the solid-phase regenerator, and the gas flow flowing through the solid-phase regenerator is stored in the buffer tank through the exhale pipeline.

[0014] The inhaling step includes: if the pressure of the top gas phase space of the storage tank reaches a predetermined lower limit value, the top gas phase space of the storage tank inhales the gas stream from the buffer tank, and the gas stream stored in the buffer tank is sucked out through the inhaling pipeline and flows through the solid phase regenerator, and finally enters the top gas phase space of the storage tank.

[0015] According to the low-temperature storage tank breathing gas recovery method provided by the application, in the exhaling step, the gas stream released by the top gas phase space of the storage tank first flows through the solid phase regenerator to be heated, and then enters the buffer tank after being pressurized and cooled in the exhaling pipeline; in the inhaling step, the gas stream in the buffer tank is first depressurized in the inhaling pipeline, and then cooled through the solid phase regenerator and then inhaled into the top gas phase space of the storage tank.

[0016] According to the low-temperature storage tank breathing gas recovery method provided by the application, in the inhaling step, if the pressure of the top gas phase space of the storage tank reaches a predetermined upper limit value, the depressurization valve of the inhaling pipeline is triggered to be opened.

[0017] According to the low-temperature storage tank breathing gas recovery method provided by the application, the low-temperature storage tank breathing gas recovery method further includes a tail gas treatment step; in the tail gas treatment step, if the pressure of the top gas phase space of the storage tank exceeds a predetermined upper limit value and reaches a dangerous early warning value, the tail gas discharge pipeline is triggered to be opened to make the gas stream released by the top gas phase space of the storage tank enter the tail gas discharge pipeline.

[0018] The low-temperature storage tank breathing gas recovery system provided by the application includes a low-temperature regenerative working medium storage tank, a medium-temperature regenerative working medium storage tank, a buffer tank and a solid phase regenerator; the low-temperature regenerative working medium storage tank is connected with the medium-temperature regenerative working medium storage tank and forms a top gas phase space of a storage tank, the top gas phase space of the storage tank is connected with the solid phase regenerator, the solid phase regenerator is connected with the buffer tank through an inhaling pipeline and an exhaling pipeline, and the inhaling pipeline and the exhaling pipeline are arranged in parallel. In the low-temperature storage tank breathing gas recovery system and method, the excess breathing gas in the top gas phase space of the storage tank is buffered by the buffer tank, so as to relieve the pressure of the top gas phase space of the storage tank and ensure the safety and stability of the top gas phase space of the storage tank.

[0019] On this basis, the solid-phase regenerator is used to recover the cold quantity of the flowing gas in the buffering process of the tank breathing gas, so that the solid-phase regenerator can be used to realize safer and more stable temperature control of the breathing gas, and the heat exchange process is not limited by the gas flow and the gas flow direction, so that the situation that the gas flow direction of the breathing gas is opposite to the energy storage stage and the energy release stage of the energy storage system can be effectively avoided.

[0020] Further, the solid-phase regenerator is used to recover the cold quantity of the gas flow from the top gas space of the tank, so that the breathing gas can be quickly warmed up, the defect of expensive equipment caused by directly low-temperature compression of the breathing gas can be avoided, the waste of the cold quantity of the gas flow can be avoided, and the overall safety and stability of the system can be improved.

[0021] Further, the solid-phase regenerator uses solid-phase regenerative materials for heat exchange and storage, and the principle is to use the low-temperature characteristics of the regenerative materials to absorb and keep the cold quantity in the cooling stage.

[0022] Therefore, the low-temperature tank breathing gas recovery system can be used in various regenerative working fluid tanks and energy storage systems with such tanks, has a wide application range, a large popularization space, and is safe and stable.

[0023] The application also provides a low-temperature tank breathing gas recovery method, which uses the above-mentioned low-temperature tank breathing gas recovery system, so as to have all the advantages of the low-temperature tank breathing gas recovery system.

[0024] And the low-temperature storage tank breathing gas recovery method specifically comprises an expiration step and an inspiration step. In the expiration step, if the pressure of the gaseous phase space at the top of the storage tank reaches a predetermined upper limit value, the gaseous phase space at the top of the storage tank releases a gas flow to the solid-phase regenerator, and the gas flow flowing through the solid-phase regenerator enters the buffer tank through the expiration pipeline and is stored in the buffer tank. In the inspiration step, if the pressure of the gaseous phase space at the top of the storage tank reaches a predetermined lower limit value, the gaseous phase space at the top of the storage tank inhales a gas flow from the buffer tank, and the gas flow stored in the buffer tank is inhaled through the inspiration pipeline and flows through the solid-phase regenerator and finally enters the gaseous phase space at the top of the storage tank. It can be seen that the method can control the buffering of the breathing gas based on the pressure of the gaseous phase space at the top of the storage tank, and can realize the autonomous judgment and execution of expiration and inspiration, so as to ensure the stability of the pressure of the gaseous phase space at the top of the storage tank, improve the safety of the gaseous phase space at the top of the storage tank, and also improve the safety and stable operation of the energy storage system connected thereto. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0026] Figure 1 is a structural schematic diagram of the low-temperature storage tank breathing gas recovery system provided by the present application.

[0027] Reference signs:

[0028] 1, medium-temperature regenerative working medium storage tank; 2, low-temperature regenerative working medium storage tank; 3, first valve body; 4, second valve body; 5, solid-phase regenerator; 6, third valve body; 7, compressor; 8, air cooler; 9, buffer tank; 10, pressure reducing valve; 11, fourth valve body; 12, discharge control valve; P, pressure gauge. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0030] The following will be described in combination with Figure 1The application discloses a low-temperature storage tank breathing gas recovery system and method. In the embodiment of the application, the low-temperature storage tank breathing gas recovery system can be referred to as a "recovery system" or "system", and the low-temperature storage tank breathing gas recovery method can be referred to as a "recovery method" or "method". The recovery system and the recovery method can be correspondingly referred to each other.

[0031] Figure 1 FIG. 1 is a structural schematic diagram of a low-temperature storage tank breathing gas recovery system provided by the application. As shown in FIG. 1, the recovery system comprises a low-temperature cold storage medium storage tank 2, a medium-temperature cold storage medium storage tank 1, a buffer tank 9 and a solid-phase cold storage device 5. Figure 1 The low-temperature cold storage medium storage tank 2 and the medium-temperature cold storage medium storage tank 1 are used to connect an external energy storage system, for example, a liquid air energy storage system. Preferably, the cold storage medium stored in the low-temperature cold storage medium storage tank 2 and the medium-temperature cold storage medium storage tank 1 is deep low-temperature cold storage medium propane. In the energy storage stage and the energy release stage of the energy storage system, as the cold storage medium enters and exits the storage tank, the pressure of the gas phase space at the top of each storage tank also changes. In order to avoid the pressure being too high and exceeding the upper limit of the design of the storage tank, the low-temperature cold storage medium storage tank 2 and the medium-temperature cold storage medium storage tank 1 are connected and constitute the storage tank top gas phase space, so that the pressure between the storage tanks can be stabilized within a certain range, and the safety of the system is improved.

[0032] In order to more stably and reliably control the operation of the recovery system, preferably, the low-temperature cold storage medium storage tank 2 and the medium-temperature cold storage medium storage tank 1 are connected through a first pipeline, and the top of the low-temperature cold storage medium storage tank 2, the first pipeline and the top of the medium-temperature cold storage medium storage tank 1 form a common linkage storage tank top gas phase space. A first valve body 3 is arranged on the first pipeline, and the first valve body 3 is used to control the opening and closing of the first pipeline.

[0033] In some embodiments, if the low-temperature cold storage medium storage tank 2 and the medium-temperature cold storage medium storage tank 1 adopt a normal-pressure storage tank, the pressure fluctuation range interval of the normal-pressure storage tank is relatively narrow, and only the storage tank top gas phase space is arranged, which is prone to cause the storage tank to be over-pressured and under-pressured. Therefore, in the embodiment of the application, a pressure container can be selected as the low-temperature cold storage medium storage tank 2 and the medium-temperature cold storage medium storage tank 1.

[0034] In some embodiments, based on the above structural arrangement and considering that the investment cost of the pressure container is relatively high, the pressure container is not suitable for being widely applied in a large-scale liquid air energy storage system. Therefore, the buffer tank 9 is additionally arranged to connect the storage tank top gas phase space, the excess breathing gas in the storage tank top gas phase space is buffered by the buffer tank 9, so that the pressure of the storage tank top gas phase space is relieved, the safety and stability of the storage tank top gas phase space are ensured, and the low-temperature cold storage medium storage tank 2 and the medium-temperature cold storage medium storage tank 1 can avoid being over-pressured and under-pressured without using a pressure container.

[0035] In some embodiments, the suction pipe and the expiration pipe are connected between the buffer tank 9 and the top gas space of the storage tank, and the suction pipe and the expiration pipe are arranged in parallel. During the operation of the system, when the top gas space of the storage tank reaches the maximum design pressure, the breathing gas in the top gas space of the storage tank can enter the buffer tank 9 through the expiration pipe; when the top gas space of the storage tank reaches the minimum design pressure, the working medium stored in the buffer tank 9 is sucked back into the top gas space of the storage tank through the suction pipe. It can be seen that the buffer tank 9, the expiration pipe and the suction pipe together constitute an external buffer device of the top gas space of the storage tank, which can stabilize the pressure of the top gas space of the storage tank and improve the safety of the system.

[0036] In some embodiments, the recovery system further comprises a compressor 7 and an air cooler 8, which are arranged in series in the expiration pipe. During the operation of the system, when the top gas space of the storage tank reaches the maximum design pressure, the slightly positive pressure gas in the top gas space of the storage tank is compressed by the compressor 7, cooled by the air cooler 8, and then stored in the buffer tank 9 in the state of normal temperature and high pressure.

[0037] In some embodiments, the recovery system further comprises a pressure reducing valve 10. The pressure reducing valve 10 is connected to the suction pipe. When the top gas space of the storage tank reaches the minimum design pressure, the working medium in the buffer tank 9 is reduced in pressure by the pressure reducing valve 10 to a slightly positive pressure state, and then enters the top gas space of the storage tank and is automatically supplemented into the corresponding storage tank under the action of pressure.

[0038] In some embodiments, in order to avoid the breathing gas being directly compressed at low temperature in the expiration pipe, thereby increasing the cost of the compressor 7 device and wasting cold energy, the system preferably further comprises a heat exchanger. The top gas space of the storage tank is connected to the expiration pipe and the suction pipe through the heat exchanger. When the top gas space of the storage tank reaches the maximum design pressure, the slightly positive pressure gas first enters the heat exchanger to release cold energy, and the breathing gas at normal temperature is compressed by the compressor 7 and cooled by the air cooler 8 during the process of flowing through the expiration pipe, and then is stored in the buffer tank 9 in the state of normal temperature and high pressure; when the top gas space of the storage tank reaches the minimum design pressure, the working medium in the buffer tank 9 is cooled to low temperature by the heat exchanger, and then is reduced in pressure to a slightly positive pressure state by the pressure reducing valve 10, and then is re-sucked into the top gas space of the storage tank. In this process, the heat exchanger not only plays a temperature regulating role, but also assists in realizing the pressure stabilizing role, increases the stability of the system, and effectively solves the problem of cold energy waste.

[0039] It should be noted that the medium stored in the medium storage tank 1 and the medium storage tank 2 in the embodiments of the present application is propane, methane, propylene and other hydrocarbon media, or trifluoromethane, difluoromethane and other halogenated hydrocarbon single medium, or a mixed medium composed of the above single medium.

[0040] It should be noted that the heat exchanger is used as the breathing gas cold recovery device in the embodiment of the present application, and the influence of nitrogen dissolution in the cold storage medium on the system is not fully considered.

[0041] When the nitrogen dissolution is not considered, in the energy storage stage of the system, the gas flowing in the gas phase space at the top of the tank is cooled to reduce the volume, and the pressure of the tank is lowered; when the lower limit of the design pressure of the tank is reached, the gas needs to be inhaled into the tank; and in the energy release stage of the system, the gas in the gas phase space at the top of the tank is heated to increase the volume, and the pressure of the tank is increased; when the upper limit of the design pressure of the tank is reached, the gas needs to be exhaled out of the tank.

[0042] When the nitrogen dissolution is considered, in the energy storage stage of the system, the gas flowing in the gas phase space at the top of the tank is cooled to reduce the volume, and the pressure of the tank is lowered; at the same time, the solubility of nitrogen decreases with the increase of temperature, and nitrogen will be released from the working gas propane, and the volume of the released nitrogen will make up for the volume reduction caused by the gas cooling to a certain extent, so whether the gas needs to be inhaled or exhaled in this stage depends on the amount of nitrogen dissolution, which is described as follows.

[0043] (1) When the volume of nitrogen released due to the cooling of the cold storage medium is less than the volume reduced by the gas cooling, the gas needs to be inhaled into the tank.

[0044] (2) When the volume of nitrogen released due to the cooling of the cold storage medium is approximately equal to the volume reduced by the gas cooling, the balance can be achieved, and no breathing gas is needed.

[0045] (3) When the volume of nitrogen released due to the cooling of the cold storage medium is greater than the volume reduced by the gas cooling, the gas needs to be exhaled out of the tank.

[0046] From the above content, it can be seen that when the amount of nitrogen dissolution in the cold storage medium changes greatly with the change of temperature, if the breathing gas recovery system is directly used without considering the nitrogen dissolution, large deviations will occur in different stages, thereby causing unstable and unsafe operation of the system.

[0047] And the energy storage system in the actual operation process will usually use nitrogen as a cold storage working gas protection, nitrogen in the cold storage working gas dissolution is inevitable, and, nitrogen in the cold storage working gas dissolved by heat caused by solubility and solubility caused by cooling and increasing also with the dissolution equilibrium time, can not simply according to the maximum amount of dissolution design. Nitrogen dissolution amount is large, may appear: just start running when nitrogen dissolution amount is small, energy storage process for the inspiration process, after several energy release cycle, reach the dissolution equilibrium, turn to the exhalation process, that is, the inspiration→ balance→ exhalation change. The change of the respiratory gas volume and the direction of the respiratory gas will lead to the difficulty of more accurate setting of the heat exchanger described in the embodiment of the application, and even lead to interference with the whole respiratory gas system, thereby affecting the normal operation of the system.

[0048] In some embodiments, in order to avoid the serious influence of nitrogen dissolution on the respiratory gas recovery system, the top gas phase space of the storage tank is connected with the solid phase cold accumulator 5, the solid phase cold accumulator 5 is connected with the buffer tank 9 through the inspiration pipeline and the exhalation pipeline respectively, and the inspiration pipeline and the exhalation pipeline are arranged in parallel. In the process of buffering the respiratory gas of the storage tank, the cold energy of the flowing gas is recovered by the solid phase cold accumulator 5, so that the characteristics of the solid phase cold accumulator 5 can be used to realize more safe and stable temperature control of the respiratory gas, and the respiratory gas flow and the direction of the respiratory gas flow are not limited in the heat exchange process, so that the situation that the direction of the respiratory gas flow is opposite to the energy storage stage and the energy release stage of the energy storage system can be effectively avoided. That is, compared with the traditional liquid phase medium heat exchange device, the low-temperature storage tank respiratory gas recovery system of the application can avoid considering the influence of nitrogen dissolution on the respiratory gas buffering process, thereby solving the problem that the nitrogen dissolution in the cold storage working gas of the large-scale liquid air energy storage system causes the difficulty of accurate design of the respiratory gas system heat exchanger.

[0049] The solid phase cold accumulator 5 recovers the cold energy of the exhalation gas flow from the top gas phase space of the storage tank, so that the respiratory gas can be quickly warmed up, the defect of expensive equipment caused by directly compressing the respiratory gas at low temperature can be effectively avoided, the waste of gas flow cold energy can be avoided, and the overall safety and stability of the system can be improved. The solid phase cold accumulator 5 uses solid phase cold storage material for heat exchange and cold storage, and the principle is to use the low-temperature characteristics of the cold storage material to absorb and keep the cold energy in the cooling stage. Compared with the traditional heat exchanger using liquid phase cold storage material and phase change cold storage material, it is more safe and environmentally friendly.

[0050] In some embodiments, the top gas space of the storage tank can store the exhaled air into the buffer tank 9 in the exhalation step, and the buffer tank 9 can supply the inhaled air to the top gas space of the storage tank in the inhalation step. The solid-phase cold accumulator 5 is used to absorb and store the cold released by the exhaled air in the exhalation step, and release the cold to the inhaled air in the inhalation step, so as to achieve heat exchange and energy storage with the exhaled air and the inhaled air. The heat exchange direction of the solid-phase cold accumulator 5 is irrelevant to the energy storage stage and the energy release stage of the energy storage system, and is only related to the exhalation step and the inhalation step. That is, the execution process of the exhalation step and the inhalation step can be executed in the energy storage stage of the energy storage system, or can be executed in the energy release stage of the energy storage system. Due to the phenomenon of nitrogen dissolution in the cold storage medium, the nitrogen dissolution amount and the nitrogen dissolution rate and other nitrogen dissolution conditions will not affect the execution of the exhalation step and the inhalation step through the above setting.

[0051] Therefore, the low-temperature storage tank breathing air recovery system can not be limited by the air flow and the air flow direction in the breathing air buffer processing process, can be applied to various cold storage medium storage tanks prone to nitrogen dissolution and energy storage systems with such storage tanks, has wide application range, large popularization space, and is safe and stable.

[0052] In order to realize stable and reliable pipeline control between the top gas space of the storage tank and the solid-phase cold accumulator 5, the top gas space of the storage tank is preferably communicated with the solid-phase cold accumulator 5 through a second pipeline, and a second valve body 4 is arranged on the second pipeline. The second valve body 4 can control the opening and closing of the second pipeline.

[0053] Similarly, in order to realize stable and reliable pipeline control of the exhalation pipeline, a third valve body 6 is preferably arranged on the exhalation pipeline, and the third valve body 6 is used to control the opening and closing of the exhalation pipeline.

[0054] Similarly, in order to realize stable and reliable pipeline control of the inhalation pipeline, a fourth valve body 11 is preferably arranged on the inhalation pipeline, and the fourth valve body 11 is used to control the opening and closing of the inhalation pipeline.

[0055] In some embodiments, the system further comprises the above-mentioned pressure reducing valve 10. The pressure reducing valve 10 is arranged in series on the inhalation pipeline, and is used to reduce the pressure of the gas flowing through, so that the breathing air is reduced to a slightly positive pressure state before entering the solid-phase cold accumulator 5, thereby improving the safety of system operation.

[0056] In some embodiments, the above-mentioned compressor 7 and air cooler 8 are arranged in series on the exhalation pipeline, and the compressor 7 and the air cooler 8 are sequentially connected between the solid-phase cold accumulator 5 and the buffer tank 9. The setting ensures that the breathing air after fully releasing the cold can be pressurized by the compressor 7 before entering the buffer tank 9, and then cooled by the air cooler 8 and reliably stored in the buffer tank 9, thereby improving the safety of system operation.

[0057] In some embodiments, the system further comprises a tail gas treatment pipeline. The tail gas treatment pipeline is connected between the top gas phase space of the storage tank and the solid phase regenerator 5. The tail gas treatment pipeline can discharge excess gas in the top gas phase space of the storage tank to the outside, so as to quickly release pressure in the case of overpressure operation of the system and improve the stability of the system. In order to realize reliable and stable pipeline control of the tail gas treatment pipeline, the tail gas treatment pipeline is preferably provided with a discharge control valve 12. The discharge control valve 12 is used to control the opening and closing of the tail gas treatment pipeline. Since the regenerative working medium used in the energy storage system is a combustible gas such as propane, in order to ensure that the gas discharge meets environmental protection standards, the tail gas treatment pipeline is preferably connected with a flare system at the gas outlet end. The flare system is used to ignite the discharged tail gas, so as to ensure that the tail gas discharge does not cause environmental pollution.

[0058] In some embodiments, the system further comprises a pressure gauge P. The pressure gauge P is connected to the top gas phase space of the storage tank and is used to monitor the gas pressure of the top gas phase space of the storage tank in real time. The pressure gauge P is preferably linked with the pressure relief valve 10 for linkage control, so that the pressure relief valve 10 can be dynamically opened and closed according to the top gas phase space of the storage tank, and the gas flow pressure value in the gas suction pipeline can be adjusted in real time, further improving the safety of the system. The pressure gauge P is preferably linked with the discharge control valve 12 for linkage control, so as to quickly discharge excess gas in the case of overpressure operation of the system, and release pressure for the system.

[0059] Based on the low-temperature storage tank breathing gas recovery system as shown in Figure 1 The embodiments of the present application further illustrate the low-temperature storage tank breathing gas recovery method. The method is executed by using the low-temperature storage tank breathing gas recovery system described above, and thus can have all the advantages of the low-temperature storage tank breathing gas recovery system described above, which will not be repeated here.

[0060] In some embodiments, the low-temperature storage tank breathing gas recovery method comprises an exhalation step and an inhalation step.

[0061] The exhalation step comprises: if the pressure of the top gas phase space of the storage tank reaches a predetermined upper limit value, the top gas phase space of the storage tank releases a gas flow to the solid phase regenerator 5, and the gas flow flowing through the solid phase regenerator 5 enters the buffer tank 9 through the exhalation pipeline and is stored in the buffer tank 9.

[0062] The inhalation step comprises: if the pressure of the top gas phase space of the storage tank reaches a predetermined lower limit value, the top gas phase space of the storage tank inhales a gas flow from the buffer tank 9, and the gas flow stored in the buffer tank 9 is sucked out through the inhalation pipeline and flows through the solid phase regenerator 5, and finally enters the top gas phase space of the storage tank.

[0063] It can be seen that the method can control the breathing gas based on the pressure of the gas phase space at the top of the tank, and can realize autonomous judgment and execution of exhalation and inhalation, so as to ensure the stability of the pressure of the gas phase space at the top of the tank, improve the safety of the gas phase space at the top of the tank, and also improve the safety and stable operation of the connected energy storage system.

[0064] In the exhalation step, the gas flow released from the gas phase space at the top of the tank first flows through the solid-phase cold accumulator 5 to release cold energy and thus warm up, and then enters the buffer tank 9 after being pressurized and cooled in the exhalation pipeline. Correspondingly, in the inhalation step, the gas flow medium in the buffer tank 9 is first depressurized in the inhalation pipeline, and then cooled by the solid-phase cold accumulator 5 before being inhaled into the gas phase space at the top of the tank. This process ensures smooth flow of the breathing gas between the gas phase space at the top of the tank and the buffer tank 9, realizes reliable buffering at normal temperature and pressure, and also realizes stable and reliable recovery to the micro-positive pressure state back to the gas phase space at the top of the tank.

[0065] In some embodiments, in the inhalation step, if the pressure of the gas phase space at the top of the tank reaches a predetermined upper limit value, the depressurization valve of the inhalation pipeline is triggered to open. This step can ensure that the pressure state of the gas phase space at the top of the tank is timely linked to the medium flow in the inhalation pipeline, that is, the gas can be inhaled from the buffer tank 9 to pressurize in time when the pressure of the gas phase space at the top of the tank is too low, avoiding damage to the system due to low pressure for too long and improving the reliability of the system.

[0066] In some embodiments, the low-temperature tank breathing gas recovery method further includes a tail gas treatment step. In the tail gas treatment step, if the pressure of the gas phase space at the top of the tank exceeds a predetermined upper limit value and reaches a dangerous warning value, the tail gas discharge pipeline is triggered to open in linkage, so that the gas flow released from the gas phase space at the top of the tank enters the tail gas discharge pipeline. This step can quickly discharge gas in time when the pressure of the gas phase space at the top of the tank of the system is too high, so as to reduce the pressure of the system in time.

[0067] Based on the above-mentioned recovery system and method, the specific operation process of the system according to the embodiments of the present application is as follows.

[0068] The system is in the exhalation phase: the exhalation step is performed.

[0069] Specifically, the first valve body 3 on the first pipeline between the medium-temperature cold storage working medium storage tank 1 and the low-temperature cold storage working medium storage tank 2 is in an open state. When the top gas space of the storage tank reaches the upper limit of the design pressure, that is, the reading of the pressure gauge P reaches the upper limit of the design pressure of the storage tank, the two cold storage working medium storage tanks need to exhale, at this time, the second valve body 4 and the third valve body 6 are opened, so that the low-temperature exhaled gas flows out from the top gas space of the storage tank, releases cold energy through the solid-phase cold storage device 5, that is, the solid-phase cold storage device 5 absorbs and stores cold energy from the exhaled gas, and the exhaled gas is warmed to the breathing gas at room temperature and enters the compressor 7 for pressurization, and then enters the buffer tank 9 after being cooled to 30 DEG C through the air cooler 8 for storage; when the pressure of the top gas space of the storage tank stops increasing, the second valve body 4 and the third valve body 6 are closed.

[0070] It should be noted that the exhalation stage does not need to be limited to the energy storage stage or the energy release stage of the system, and the relevant control circuit is triggered only when the pressure of the top gas space of the storage tank reaches the maximum value to execute the exhalation stage.

[0071] The system is in the inhalation stage: the inhalation step is executed.

[0072] Specifically, the first valve body 3 on the first pipeline between the medium-temperature cold storage working medium storage tank 1 and the low-temperature cold storage working medium storage tank 2 is in an open state. When the top gas space of the storage tank reaches the upper limit of the design pressure, that is, the reading of the pressure gauge P reaches the upper limit of the design pressure of the storage tank, the two cold storage working medium storage tanks need to inhale, at this time, the second valve body 4 and the fourth valve body 11 are opened, and the interlocking pressure relief valve 10 is automatically triggered to open, so that the breathing gas at room temperature and high pressure stored in the buffer tank 9 is reduced in pressure to a slightly positive pressure state through the pressure relief valve 10, and then enters the solid-phase cold storage device 5 to absorb cold energy, and is cooled to a low temperature to enter the cold storage working medium storage tank as inhaled gas for pressure compensation.

[0073] It should be noted that the inhalation stage does not need to be limited to the energy storage stage or the energy release stage of the system, and the relevant control circuit is triggered only when the pressure of the top gas space of the storage tank reaches the minimum value to execute the inhalation stage.

[0074] Further, in order to ensure the safety of the system, when the amount of breathing gas exceeds the upper limit of the design of the system, in order to avoid overpressure operation of the system, the excess breathing gas needs to be transported to the flare system through the tail gas discharge pipeline. That is, when the pressure gauge P reaches the upper limit and a high alarm occurs, the discharge control valve 12 is automatically triggered to open, so that the excess breathing gas in the top gas space of the storage tank is discharged to the flare system.

[0075] It should be noted that when the system and the method described in the embodiment of the application are designed according to the condition that nitrogen is not completely dissolved, the two cold storage working medium storage tanks in the above system inhale in the energy storage stage and exhale in the energy release stage.

[0076] It should be noted that the system and method of the embodiment of the present application considers the nitrogen dissolution, because the direction of the breathing gas of the system can be opposite, the breathing gas amount changes with the time required for the nitrogen to reach the dissolution equilibrium in the working medium and the storage and release energy operation time is different, but because the system of the embodiment of the present application uses the solid phase cold accumulator 5 as the cold quantity recovery mechanism of the breathing gas, which is different from the heat exchanger using liquid phase heat exchange medium, the solid phase cold accumulator 5 does not have strict requirements for the gas inlet direction and the gas inlet amount, so the nitrogen dissolution condition does not affect the normal operation of the system.

[0077] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A cryogenic storage tank breather gas recovery system, characterized by, The low-temperature cold storage medium tank and the medium-temperature cold storage medium tank are connected to the energy storage system; the low-temperature cold storage medium tank and the medium-temperature cold storage medium tank are connected and form a gas phase space at the top of the tank, the gas phase space at the top of the tank is connected to the solid-phase cold storage device, the solid-phase cold storage device is connected to the buffer tank through a gas suction pipeline and a gas discharge pipeline, and the gas suction pipeline and the gas discharge pipeline are connected in parallel; The gas phase space at the top of the tank can store exhaled gas into the buffer tank in the gas discharge step, and the buffer tank can supplement inhaled gas into the gas phase space at the top of the tank in the gas suction step; The solid-phase cold storage device is used for absorbing and storing the cold energy released by the exhaled gas in the gas discharge step, and releasing the cold energy to the inhaled gas in the gas suction step, so as to realize heat exchange energy storage with the exhaled gas and the inhaled gas; The heat exchange direction of the solid-phase cold storage device is irrelevant to the energy storage stage and the energy release stage of the energy storage system.

2. The cryogenic storage tank breather gas recovery system of claim 1, wherein, A pressure reducing valve is installed in series in the gas suction pipeline, and a pressure gauge is connected to the gas phase space at the top of the tank, and the pressure gauge is linked to control the pressure reducing valve.

3. The cryogenic storage tank breather gas recovery system of claim 2, wherein, An exhaust treatment pipeline is connected between the gas phase space at the top of the tank and the solid-phase cold storage device; the exhaust treatment pipeline is provided with a discharge control valve, and the pressure gauge is linked to control the discharge control valve.

4. The cryogenic storage tank breather gas recovery system of claim 3, wherein, The exhaust treatment pipeline is connected with a flare system.

5. The cryogenic storage tank breather gas recovery system of any of claims 1-4, wherein, A compressor and an air cooler are installed in series in the gas discharge pipeline, and the compressor and the air cooler are sequentially connected between the solid-phase cold storage device and the buffer tank.

6. The cryogenic storage tank breather gas recovery system of any of claims 1-4, wherein, The low-temperature cold storage medium tank and the medium-temperature cold storage medium tank are connected through a first pipeline, the first pipeline is provided with a first valve body; the gas phase space at the top of the tank and the solid-phase cold storage device are connected through a second pipeline, the second pipeline is provided with a second valve body; the gas discharge pipeline is provided with a third valve body, and the gas suction pipeline is provided with a fourth valve body.

7. A method of recovering boil-off gas from a cryogenic storage tank, the method comprising: The low-temperature tank breathing gas recovery system is executed by using the low-temperature tank breathing gas recovery system according to any one of claims 1-6; the low-temperature tank breathing gas recovery method comprises a gas discharge step and a gas suction step; The gas discharge step comprises: If the pressure of the gas phase space at the top of the tank reaches a predetermined upper limit value, the gas phase space at the top of the tank releases a gas flow to the solid-phase cold storage device, and the gas flow flowing through the solid-phase cold storage device enters the buffer tank through the gas discharge pipeline and is stored; The gas suction step comprises: If the pressure of the gas phase space at the top of the tank reaches a predetermined lower limit value, the gas phase space at the top of the tank inhales a gas flow from the buffer tank, and the gas flow stored in the buffer tank is sucked out through the gas suction pipeline and flows through the solid-phase cold storage device, and finally enters the gas phase space at the top of the tank.

8. The low-temperature tank breathing gas recovery method according to claim 7, wherein In the expiration step, the gas stream released from the gas phase space on top of the storage tank is first warmed up in the solid-state regenerator, and then is stored in the buffer tank after being pressurized and cooled down in the expiration pipeline; In the inspiration step, the gas stream in the buffer tank is first depressurized in the inspiration pipeline, and then is inspired into the gas phase space on top of the storage tank after being cooled down in the solid-state regenerator.

9. The cryogenic storage tank breather gas recovery method of claim 8, wherein, In the inspiration step, if the pressure of the gas phase space on top of the storage tank reaches a predetermined upper limit value, the opening of the depressurization valve in the inspiration pipeline is triggered.

10. The cryogenic storage tank breather gas recovery method of claim 7, wherein, The low-temperature storage tank breathing gas recovery method further comprises a tail gas treatment step; In the tail gas treatment step, if the pressure of the gas phase space on top of the storage tank exceeds a predetermined upper limit value and reaches a dangerous warning value, the opening of the tail gas discharge pipeline is triggered to make the gas stream released from the gas phase space on top of the storage tank enter the tail gas discharge pipeline.

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