Compressed air energy storage spherical tank reverse operation system and operation method thereof

Abstract

This invention discloses a compressed air energy storage spherical tank switching operation system and its operation method, belonging to the field of energy storage equipment. It includes interconnected thermal energy storage tanks, cold energy storage tanks, and several bidirectional energy storage tanks. The thermal / cold energy storage tanks are equipped with high / low temperature water inlets and outlets, while the bidirectional energy storage tanks are equipped with low / high temperature water inlets and outlets. The low / high temperature outlets are connected to a common low / high temperature main water outlet pipeline, and the low / high temperature inlets are connected to a common low / high temperature main water inlet pipeline. A high-temperature heat transfer fluid pump assembly and a heat exchanger assembly are connected to the high-temperature main water outlet pipeline, which then connects to the low-temperature main water inlet pipeline. Similarly, a low-temperature heat transfer fluid pump assembly and a heat exchanger assembly are connected to the low-temperature main water outlet pipeline, which then connects to the high-temperature main water inlet pipeline. A pressure regulating assembly is connected to the cold energy storage tank. This invention solves the problems of thermal stress accumulation and delayed switching response in existing systems, thereby ensuring the long-term reliable operation of the thermal energy storage system.

Description

Technical Field

[0001] This invention relates to the field of energy storage equipment, and in particular to a compressed air energy storage spherical tank switching operation system and its operation method. Background Technology

[0002] Compressed air energy storage, as a core component of emerging energy storage technologies, is a crucial technological means to enhance the regulation capabilities of power systems and ensure stable energy supply. It has already laid the foundation for large-scale commercial application. With continuous technological advancements in the industry, the operational efficiency requirements for compressed air energy storage power plants are constantly increasing. Since the heat exchange temperature is a core factor restricting the overall efficiency of the power plant, its improvement directly impacts the economic viability of the plant's operation. Therefore, optimizing the heat exchange process has become a key direction for further development of compressed air energy storage technology.

[0003] In the design of thermal storage systems, water-based heat exchange media is widely used in compressed air energy storage power plants due to its significant advantages of lower initial investment and controllable operation and maintenance costs. Since atmospheric water needs to be pressurized during the thermal storage process, the associated storage tanks are all pressurized tanks, and nitrogen pressure stabilization is typically used to ensure operational safety. To further reduce tank construction costs and floor space, existing thermal storage systems often only use hot water spherical tanks, storing low-temperature and high-temperature water alternately. However, the significant temperature difference between low-temperature and high-temperature water causes rapid temperature changes when switching storage media. In frequent charge-discharge cycles, even with a limited number of cycles, the spherical tanks are prone to fatigue damage due to continuous thermal stress accumulation, severely impacting long-term reliable operation and failing to meet the long-term stable service requirements of the power plant.

[0004] Besides reliability issues caused by thermal stress, existing thermal energy storage systems also suffer from insufficient switching flexibility. In the traditional compressed air energy storage system operation mode, the entire thermal energy storage tank must complete the forward energy storage process (conversion from cold water to hot water) before it can be switched to the reverse energy release process (conversion from hot water to cold water). It cannot dynamically adjust the operating mode based on the real-time storage status and temperature of individual tanks. This "overall synchronization" switching method not only leads to a lag in the system's response to changes in operating conditions but also results in energy waste during switching intervals, significantly limiting the system's energy utilization rate and contradicting the power plant's goal of pursuing high-efficiency operation.

[0005] The reliability risks caused by thermal stress and the efficiency problems resulting from insufficient switching flexibility, as mentioned above, jointly restrict the long-term operational stability and economic efficiency of compressed air energy storage power stations. Therefore, there is an urgent need for an optimized compressed air energy storage spherical tank operating system and corresponding operating methods. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a compressed air energy storage spherical tank switching operation system and its operation method. By improving the operation logic of the thermal storage spherical tank, the problems of thermal stress accumulation and switching response lag in the existing system are solved, thereby ensuring the long-term reliable operation of the thermal storage system, while improving energy utilization efficiency and meeting the high-efficiency and stable operation requirements of compressed air energy storage power stations.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by this invention is: a compressed air energy storage spherical tank switching operation system, comprising a hot energy storage tank, a cold energy storage tank, and several bidirectional energy storage tanks interconnected by a nitrogen pressure stabilizing pipeline. The hot energy storage tank is equipped with a high-temperature water inlet and a high-temperature water outlet; the cold energy storage tank is equipped with a low-temperature water inlet and a low-temperature water outlet; and the bidirectional energy storage tank is equipped with a low-temperature water inlet, a low-temperature water outlet, a high-temperature water inlet, and a high-temperature water outlet. The low-temperature water outlets of all tanks are connected to a common low-temperature water outlet main pipeline via branch pipelines, and the low-temperature water inlets of all tanks are connected to a common low-temperature water inlet main pipeline via branch pipelines. The high-temperature water outlets of the tanks are connected to a common high-temperature water main pipeline via branch pipes, and the high-temperature water inlets of all tanks are connected to a common high-temperature water main pipeline via branch pipes. A high-temperature heat medium water pump assembly is connected to the high-temperature heat medium water pump assembly, and a heat exchanger assembly is connected to the high-temperature heat medium water pump assembly. The cold water outlet of the heat exchanger assembly is connected to the low-temperature water main pipeline via a pipe. A low-temperature heat medium water pump assembly is connected to the low-temperature heat medium water pump assembly, and a heat exchanger assembly is connected to the low-temperature heat medium water pump assembly. The hot water outlet of the heat exchanger assembly is connected to the high-temperature water main pipeline via a pipe. A pressure regulating assembly is connected to the cold energy storage tank.

[0008] A further improvement of the technical solution of this invention is that: electric shut-off valves are installed on the high-temperature inlet and high-temperature outlet of the thermal energy storage tank, and temperature sensors, pressure sensors, and liquid level sensors are installed inside the thermal energy storage tank; electric shut-off valves are installed on the low-temperature inlet and low-temperature outlet of the cold energy storage tank, and temperature sensors, pressure sensors, and liquid level sensors are installed inside the cold energy storage tank; electric shut-off valves are installed on the high-temperature inlet, high-temperature outlet, low-temperature inlet, and low-temperature outlet of the bidirectional energy storage tank, and temperature sensors, pressure sensors, and liquid level sensors are installed inside the bidirectional energy storage tank; electromagnetic flow meters and temperature transmitters are installed at each branch connection point of the low-temperature inlet main pipe, the high-temperature inlet main pipe, the low-temperature outlet main pipe, and the high-temperature outlet main pipe, as well as in the inlet and outlet pipes of the heat exchanger, for detecting temperature and flow rate.

[0009] A further improvement of the technical solution of the present invention is that: the pressure regulating component includes a pressure regulating pipe connected to the inside of the cold storage tank, and two branches are connected to the pressure regulating pipe: pipe one and pipe two. The ends of pipe one and pipe two are connected to the pressure regulating water tank at the same time. Pipe one is equipped with a filter screen, a shut-off valve and a pressure regulating water pump, and pipe two is equipped with a shut-off valve, a three-way valve and a filter screen.

[0010] A further improvement of the technical solution of the present invention is that: the high-temperature heat transfer medium pump assembly includes multiple parallel branches, half of which is a high-temperature mixing branch and the other half is a high-temperature heat transfer medium branch. The high-temperature mixing branch includes an electrically operated shut-off valve, a three-way valve, a high-temperature mixing water pump, an electrically operated shut-off valve, and a check valve connected in sequence; the high-temperature heat transfer medium branch includes an electrically operated shut-off valve, a three-way valve, a high-temperature heat transfer medium pump, an electrically operated shut-off valve, and a check valve connected in sequence; the low-temperature heat transfer medium pump assembly includes multiple parallel branches, half of which is a low-temperature mixing branch and the other half is a low-temperature heat transfer medium branch. The low-temperature mixing branch includes an electrically operated shut-off valve, a three-way valve, a low-temperature mixing water pump, an electrically operated shut-off valve, and a check valve connected in sequence; the low-temperature heat transfer medium branch includes an electrically operated shut-off valve, a three-way valve, a low-temperature heat transfer medium pump, an electrically operated shut-off valve, and a check valve connected in sequence.

[0011] An operation method for a compressed air energy storage spherical tank transfer system includes the following steps:

[0012] Step 1: Initially, the thermal energy storage tank is empty, while the cold energy storage tank and the bidirectional energy storage tank are filled with cold water;

[0013] Step 2: Confirm the prerequisites for any bidirectional energy storage tank or cold energy storage tank, and check the temperature and pressure conditions;

[0014] Step 3: When the preconditions are met, the forward energy storage is activated. Any bidirectional energy storage tank or cold energy storage tank sends cold water through the low-temperature heat medium water pump assembly into the heat exchanger to exchange heat into hot water, which is then stored in the thermal energy storage tank.

[0015] Step 4: After the thermal energy storage tank is full, any cold energy storage tank or bidirectional energy storage tank filled with cold water can send the cold water to the heat exchanger through the low temperature heat medium water pump assembly to exchange heat into hot water and store it in the corresponding empty tank.

[0016] Step 5: During the forward energy storage process, the wall temperature rise of the tank into which hot water is stored is detected. If it rises too quickly, a low-temperature mixing circuit is used for temperature control.

[0017] Step 6: Confirm the prerequisites for any bidirectional energy storage tank or thermal energy storage tank, and check the temperature and pressure conditions;

[0018] Step 7: When the preconditions are met, reverse energy release is activated, and any bidirectional energy storage tank or thermal energy storage tank sends hot water through a high-temperature heat medium pump assembly to a heat exchanger to exchange heat into cold water, which is then stored in a cold energy storage tank.

[0019] Step 8: After the cold storage tank is full, any hot storage tank or bidirectional storage tank filled with hot water can send the hot water through the high-temperature heat medium water pump assembly to the heat exchanger to exchange heat into cold water and store it in the corresponding empty tank.

[0020] Step 9: During the reverse energy release process, the wall temperature of the tank containing cold water is detected to drop. If the temperature drops too quickly, a high-temperature mixing circuit is used for temperature control.

[0021] A further improvement to the technical solution of this invention is as follows: In steps 2 and 6, the prerequisite for allowing forward energy storage is that the water temperature inside the tank is <80℃ and the pressure is <the upper limit of the constant pressure operating pressure. When the water temperature inside the tank is ≥240℃ or the pressure is ≥P7 constant pressure water discharge opening pressure, forward termination is triggered, and the system can switch to reverse. The prerequisite for allowing reverse energy release is that the water temperature inside the tank is >200℃ and the pressure is >the constant pressure water supply opening pressure. When the water temperature inside the tank is ≤50℃ or the pressure is ≤the lower limit of the constant pressure operating pressure, reverse termination is triggered, and the system can switch to forward.

[0022] A further improvement to the technical solution of this invention lies in the following: when the pressure inside the tank does not meet the requirements, pressure is regulated by a pressure regulating component. Specifically, during forward energy storage, when the pressure inside the tank is greater than the pressure regulating discharge opening pressure, water is discharged from the cold energy storage tank to the pressure regulating water tank through pipe one at a pressure regulating discharge flow rate; during reverse energy release, when the pressure inside the tank is less than the pressure regulating water supply opening pressure, the pressure regulating water pump in pipe two is activated to replenish water to the cold energy storage tank at a certain flow rate; as detailed below:

[0023] The constant pressure water pump makeup water flow rate during reverse energy release is

[0024]

[0025] in High-temperature water flow rate during reverse energy release under design conditions; Density of water at low temperatures; The density of water at high temperatures; Temperature compensation coefficient;

[0026] The constant pressure water discharge flow rate during positive energy storage is

[0027]

[0028] in : High-temperature water flow rate during positive energy release under design conditions; Real-time pressure of the cold storage tank; The upper limit of constant pressure operation; Pressure safety margin; Pipeline flow loss coefficient.

[0029] A further improvement to the technical solution of the present invention lies in the fact that the adjustment methods in steps 5 and 9 are specifically as follows:

[0030] The wall temperature rise rate during forward energy storage is controlled as follows:

[0031]

[0032] Specific heat capacity of water at constant pressure at high temperature; Actual high-temperature water flow rate injected; : Actual temperature of the injected high-temperature water; Initial temperature of the tank wall; : Tank wall quality; Specific heat capacity of the tank wall material; : Heat exchange area correction factor; : Mixing temperature adjustment coefficient;

[0033] Control of the rate of decrease in wall temperature during reverse energy release:

[0034]

[0035] Specific heat capacity of water at constant pressure in low temperature; Actual injection flow rate of low-temperature water; : Actual temperature of the injected low-temperature water; High-temperature mixing temperature adjustment coefficient.

[0036] The corresponding valve opening degree for the mixing branch is corrected as follows:

[0037]

[0038] Initial opening degree of the mixing valve; : Upper limit of safe rate of change of wall temperature; : Actual wall temperature change rate.

[0039] Due to the adoption of the above technical solutions, the technical progress achieved by this invention is as follows: through the independent flow channel design of multiple spherical tanks and dynamic adjustment of the mixing water, the forward and reverse switching of a single spherical tank at any process moment is realized, breaking through the limitation of the traditional system that requires global tank synchronous switching. By setting up mixing branch to adjust the flow rate, real-time wall temperature status assessment, mixing water temperature difference control and multiple safety protection mechanisms, the flexibility, energy utilization rate and service life of the compressed air energy storage system are significantly improved, making it suitable for large-scale energy storage scenarios. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the structure of the inverted tank operation system of the present invention;

[0042] Among them, 1. Thermal energy storage tank, 2. Cold energy storage tank, 3. Two-way energy storage tank, 4. High temperature heat medium water pump assembly, 41. High temperature mixing branch, 42. High temperature heat medium branch, 411. High temperature mixing water pump, 421. High temperature heat medium water pump, 5. Low temperature heat medium water pump assembly, 51. Low temperature mixing branch, 511. Low temperature mixing water pump, 52. Low temperature heat medium branch, 521. Low temperature heat medium water pump, 6. Pressure regulating assembly, 61. Pressure regulating pipe, 62. Pipeline 1, 63. Pipeline 2, 64. Pressure regulating water tank. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to embodiments:

[0044] like Figure 1The diagram shows a structural schematic of a compressed air energy storage spherical tank switching operation system, including a thermal energy storage tank 1, a cold energy storage tank 2, and several bidirectional energy storage tanks 3 interconnected by nitrogen pressure stabilization pipelines. In this embodiment, there are a total of 6 tanks, including 4 bidirectional energy storage tanks 3, one cold energy storage tank 2, four bidirectional energy storage tanks 3 arranged sequentially as tank 2, tank 3, tank 4, and tank 5, and six thermal energy storage tanks 1. The thermal energy storage tank 1 is equipped with a high-temperature water inlet and a high-temperature water outlet. The cold energy storage tank 2 is equipped with a low-temperature water inlet and a low-temperature water outlet. Each of the four bidirectional energy storage tanks 3 is equipped with a low-temperature water inlet, a low-temperature water outlet, a high-temperature water inlet, and a high-temperature water outlet. The low-temperature water outlets of all tanks are connected to a common low-temperature water outlet main pipeline via branch pipelines. The low-temperature water inlets of all tanks are connected to a common low-temperature water inlet main pipeline via branch pipelines. The high-temperature water outlets of all tanks are connected to a common high-temperature water outlet main pipeline via branch pipelines. The inlet is connected to a common high-temperature main inlet pipe via a branch pipe; a high-temperature heat medium water pump assembly 4 is connected to the high-temperature outlet main pipe, and a heat exchanger assembly is connected to the high-temperature heat medium water pump assembly. The cold water outlet of the heat exchanger assembly is connected to the low-temperature main inlet pipe via a pipe; a low-temperature heat medium water pump assembly 5 is connected to the low-temperature outlet main pipe, and a heat exchanger assembly is connected to the low-temperature heat medium water pump assembly. The hot water outlet of the heat exchanger assembly is connected to the high-temperature main inlet pipe via a pipe; a pressure regulating assembly 6 is connected to the cold storage tank. Electric shut-off valves are installed on the high-temperature inlet and outlet of the thermal energy storage tank 1. Temperature sensors, pressure sensors, and liquid level sensors are installed inside the thermal energy storage tank 1. Electric shut-off valves are installed on the low-temperature inlet and outlet of the cold energy storage tank 2. Temperature sensors, pressure sensors, and liquid level sensors are installed inside the cold energy storage tank 2. Electric shut-off valves are installed on the high-temperature inlet, high-temperature outlet, low-temperature inlet, and low-temperature outlet of the bidirectional energy storage tank 3. Temperature sensors, pressure sensors, and liquid level sensors are installed inside the bidirectional energy storage tank 3. Electromagnetic flow meters and temperature transmitters are installed at each branch connection point of the low-temperature inlet main pipe, the high-temperature inlet main pipe, the low-temperature outlet main pipe, and the high-temperature outlet main pipe, as well as in the inlet and outlet pipes of the heat exchanger, for detecting temperature and flow rate. The pressure regulating component 6 includes a pressure regulating pipe connected to the inside of the cold storage tank 2. The pressure regulating pipe is connected to two branches: pipe one and pipe two. The ends of pipe one and pipe two are connected to the pressure regulating water tank. Pipe one is equipped with a filter screen, a shut-off valve and a pressure regulating water pump. Pipe two is equipped with a shut-off valve, a three-way valve and a filter screen.The high-temperature heat transfer medium pump assembly 4 includes multiple parallel branches, half of which are high-temperature mixing branches and the other half are high-temperature heat transfer medium branches. In this embodiment, there are four parallel branches, including two high-temperature mixing branches 41 and two high-temperature heat transfer medium branches 42. The high-temperature mixing branch 41 includes an electrically operated shut-off valve, a three-way valve, a high-temperature mixing water pump 411, an electrically operated shut-off valve, and a check valve connected in sequence. The high-temperature heat transfer medium branch 42 includes an electrically operated shut-off valve, a three-way valve, a high-temperature heat transfer medium pump 421, an electrically operated shut-off valve, and a check valve connected in sequence. The low-temperature heat transfer medium pump assembly 5 includes multiple parallel branches, half of which are low-temperature mixing branches 51 and the other half are low-temperature heat transfer medium branches 52. In this embodiment, there are four parallel branches, including two low-temperature mixing branches 51 and two low-temperature heat transfer medium branches 52. The low-temperature mixing branch includes an electrically operated shut-off valve, a three-way valve, a low-temperature mixing water pump 511, an electrically operated shut-off valve, and a check valve connected in sequence; the low-temperature heat medium branch includes an electrically operated shut-off valve, a three-way valve, a low-temperature heat medium water pump 521, an electrically operated shut-off valve, and a check valve connected in sequence.

[0045] The operation method of the above-mentioned compressed air energy storage spherical tank switching system includes the following steps:

[0046] Step 1: Initially, thermal energy storage tank 1 is empty, while cold energy storage tank 2 and bidirectional energy storage tank 3 are filled with cold water;

[0047] Step 2: Confirm the prerequisites for any bidirectional energy storage tank 3 or cold energy storage tank 2, and check the temperature and pressure conditions. The prerequisites for forward energy storage are that the water temperature inside the tank is <80℃ and the pressure is <the upper limit of the constant pressure operating pressure. When the water temperature inside the tank is ≥240℃ or the pressure is ≥P7 constant pressure drain opening pressure, forward termination is triggered, and it can be switched to reverse. When the pressure inside the tank does not meet the conditions, the pressure is regulated by the constant pressure component 6. Specifically, during forward energy storage, when the pressure inside the tank is > the constant pressure drain opening pressure, water is drained from the cold energy storage tank 2 to the constant pressure water tank through pipe 1 at a constant pressure drain flow rate. The constant pressure drain flow rate during forward energy storage is:

[0048]

[0049] : High-temperature water flow rate during reverse energy release under design conditions (typically taken as 50-150 t / h);

[0050] Density of water at low temperatures (kg / m³).

[0051] Density of hot water (kg / m³);

[0052] Temperature compensation coefficient (adjusted according to the deviation between the actual temperature inside the tank and the design temperature, with a value range of 0.95-1.05; when the temperature inside the tank is lower than the design value, take 1.02-1.05; when it is higher than the design value, take 0.95-0.98).

[0053] Step 3: When the preconditions are met, the forward energy storage is activated. Any bidirectional energy storage tank 3 or cold energy storage tank 2 sends cold water through the low-temperature heat medium water pump assembly 5 into the heat exchanger to exchange heat into hot water, which is then stored in the thermal energy storage tank 1.

[0054] Step 4: After thermal energy storage tank 1 is full, any cold energy storage tank 2 or bidirectional energy storage tank 3 filled with cold water can send the cold water through the low-temperature heat medium water pump assembly 5 into the heat exchanger for heat exchange and store it as hot water in the corresponding empty tank. Taking the complete forward energy storage process as an example, during complete energy storage, the electric shut-off valve at the low-temperature water outlet of the five tanks is opened, and the cold water in the tank enters the low-temperature water outlet main pipeline from the branch pipe, and then enters the four parallel branches in the low-temperature heat medium water pump assembly 5 and enters the heat exchanger that cooperates with the compressed air storage tank. After heat exchange, the hot water enters the high-temperature inlet main pipe. The high-temperature inlets of only six tanks are opened, and hot water is stored in tank six, leaving tank five empty. Then, four tanks of cold water undergo heat exchange to become hot water and are stored in tank five, leaving tank four empty. Three tanks of cold water undergo heat exchange to become hot water and are stored in tank four, two tanks of cold water undergo heat exchange to become hot water and are stored in tank three, and one tank of cold water undergoes heat exchange to become hot water and is stored in tank two. This completes the heat storage process, reaching the maximum heat storage capacity. Heat exchange and energy storage can also be performed between any two tanks as needed.

[0055] Step 5: During the forward energy storage process, the wall temperature rise of the hot water storage tank is detected. If it rises too quickly, the low-temperature mixing branch is used to reduce the flow rate. Specifically, the opening of the electric shut-off valve on the low-temperature mixing branch is controlled to adjust the cold water inlet flow rate, thereby reducing the amount of hot water injected after heat exchange and controlling the temperature.

[0056] Formula for controlling the rate of wall temperature rise during forward energy storage

[0057]

[0058] Specific heat capacity of water at constant pressure at high temperature (kJ / (kg℃));

[0059] Actual high-temperature water flow rate injected (t / h, monitored by an electromagnetic flow meter);

[0060] : Actual temperature of the injected high-temperature water (°C, monitored by a temperature transmitter);

[0061] Initial temperature of the tank wall (°C, monitored by an embedded temperature sensor in the tank wall).

[0062] : Tank wall mass (t, calculated from the tank dimensions);

[0063] Specific heat capacity of the spherical tank wall material (kJ / (kg℃));

[0064] : Heat exchange area correction factor (dimensionless, considering the contact area between hot water and tank wall, valued at 0.8-0.95, 0.95 when the tank is full).

[0065] Mixing temperature regulation coefficient (dimensionless; the higher the flow rate of the low-temperature mixing branch, the better). The larger (the larger).

[0066] The corresponding formula for correcting the opening degree of the shut-off valve on the low-temperature mixing branch is:

[0067]

[0068] Initial opening degree of the mixing valve (%, typically 0%-50%);

[0069] : Upper limit of safe rate of change of wall temperature (°C / min, 13°C / min for positive direction).

[0070] Actual wall temperature change rate (°C / min, calculated in real time by the tank wall temperature sensor);

[0071] Example: During forward energy storage, =13℃ / min, =15℃ / min, =40%, then (The negative sign indicates that the valve is closed slightly; the actual opening should be a reasonable value between 0% and 40%, such as closing it to 30%). Temperature control should be performed according to the formula to prevent the temperature from rising too quickly and to extend the service life of the tank.

[0072] Step 6: Confirm the prerequisites for any bidirectional energy storage tank 3 or thermal energy storage tank 1, and check the temperature and pressure conditions; when releasing energy in reverse, if the pressure inside the tank is less than the constant pressure water supply opening pressure, start the constant pressure water pump of pipeline 2 to replenish water to the cold energy storage tank (2) at a certain flow rate; the details are as follows:

[0073] During reverse energy release, the constant pressure water pump makeup water flow rate is

[0074]

[0075] Specific heat capacity of water at constant pressure at low temperature (kJ / (kg℃));

[0076] Actual injection flow rate of low-temperature water (t / h, monitored by an electromagnetic flow meter);

[0077] Actual temperature of the injected cryogenic water (°C, monitored by a temperature transmitter);

[0078] High-temperature mixing temperature adjustment coefficient (dimensionless; the higher the flow rate of the high-temperature mixing branch, the better). The smaller).

[0079] Step 7: When the preconditions are met, reverse energy release is activated, and hot water from either bidirectional energy storage tank 3 or thermal energy storage tank 1 is sent to the heat exchanger via the high-temperature heat medium water pump assembly 4 to exchange heat into cold water, which is then stored in the cold energy storage tank 2.

[0080] Step 8: After the cold storage tank 2 is full, the hot storage tank 1 or the bidirectional storage tank 3, which is filled with hot water, can send the hot water through the high-temperature heat medium water pump assembly 4 into the heat exchanger to exchange heat and convert it into cold water, which is then stored in the corresponding empty tank. Taking the complete reverse energy release as an example, during the complete energy release, the electric shut-off valve at the high-temperature outlet of the two tanks is opened, and the hot water in the tank enters the high-temperature outlet main pipeline from the branch pipe, and then enters the four parallel branches in the high-temperature heat medium water pump assembly 5 to enter the heat exchanger that is matched with the compressed air storage tank for heat exchange. After heat exchange, it is converted into cold water and then enters the high-temperature outlet main pipeline. The system enters the low-temperature inlet main pipeline. The low-temperature inlet of only one tank is opened, and cold water is stored in tank one. Tank two remains empty. Then, hot water from tank three is transferred to tank two after heat exchange, leaving tank three empty. Hot water from tank four is transferred to tank three after heat exchange, leaving tank four empty. Hot water from tank five is transferred to tank four after heat exchange, leaving tank five empty. Finally, hot water from tank six is ​​transferred to tank five after heat exchange, completing the energy release process. Energy can be released between any two tanks as needed, allowing for flexible energy conversion without requiring the entire tank to be fully stored before overall energy release.

[0081] Step 9: During the reverse energy release process, the wall temperature of the tank containing cold water is detected to decrease. If the decrease is too rapid, the high-temperature mixing branch is used to reduce the flow rate. Specifically, this is achieved by controlling the opening of the electric shut-off valve on the high-temperature mixing branch to adjust the hot water inlet flow rate, thereby reducing the amount of cold water injected after heat exchange and controlling the temperature.

[0082] Formula for controlling the rate of decrease in wall temperature during reverse energy release

[0083]

[0084] Specific heat capacity of water at constant pressure at low temperature (kJ / (kg℃));

[0085] Actual injection flow rate of low-temperature water (t / h, monitored by an electromagnetic flow meter);

[0086] Actual temperature of the injected cryogenic water (°C, monitored by a temperature transmitter);

[0087] High-temperature mixing temperature adjustment coefficient (dimensionless; the higher the flow rate of the high-temperature mixing branch, the better). The smaller the value, the better. The corresponding formula for correcting the opening degree of the shut-off valve on the high-temperature mixing branch is:

[0088]

[0089] Initial opening degree of the mixing valve (%, typically 0%-50%);

[0090] : Upper limit of safe wall temperature change rate (℃ / min, reverse is 10℃ / min);

[0091] Actual wall temperature change rate (°C / min, calculated in real time by the tank wall temperature sensor);

[0092] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A compressed air energy storage spherical tank switching operation system, characterized in that: The system includes a thermal energy storage tank (1), a cold energy storage tank (2), and several bidirectional energy storage tanks (3) interconnected by a nitrogen pressure-stabilizing pipeline. The thermal energy storage tank (1) is equipped with a high-temperature water inlet and a high-temperature water outlet. The cold energy storage tank (2) is equipped with a low-temperature water inlet and a low-temperature water outlet. The bidirectional energy storage tanks (3) are equipped with a low-temperature water inlet, a low-temperature water outlet, a high-temperature water inlet, and a high-temperature water outlet. All low-temperature water outlets are connected to a common low-temperature water outlet main pipeline through branch pipelines. All low-temperature water inlets are connected to a common low-temperature water inlet main pipeline through branch pipelines. All high-temperature water outlets are connected to a common high-temperature water outlet main pipeline through branch pipelines. On the main outlet pipe, all high-temperature water inlets are connected to the common high-temperature water inlet main pipe through branch pipes; a high-temperature heat medium water pump assembly (4) is connected to the high-temperature water outlet main pipe, and a heat exchanger assembly is connected to the high-temperature heat medium water pump assembly (4). The cold water outlet of the heat exchanger assembly is connected to the low-temperature water inlet main pipe through a pipe; a low-temperature heat medium water pump assembly (5) is connected to the low-temperature heat medium water pump assembly (5), and a heat exchanger assembly is connected to the low-temperature heat medium water pump assembly (5). The hot water outlet of the heat exchanger assembly is connected to the high-temperature water inlet main pipe through a pipe; a constant pressure assembly (6) is connected to the cold storage tank (2). The high-temperature heat medium water pump assembly (4) includes multiple parallel branches, half of which is a high-temperature mixing branch (41) and the other half is a high-temperature heat medium branch (42). The high-temperature mixing branch (41) includes an electric shut-off valve, a three-way valve, a high-temperature mixing water pump (411), an electric shut-off valve, and a check valve connected in sequence. The high-temperature heat medium branch (42) includes an electric shut-off valve, a three-way valve, a high-temperature heat medium water pump (421), an electric shut-off valve, and a check valve connected in sequence. The low-temperature heat transfer medium pump assembly (5) includes multiple parallel branches, half of which is a low-temperature mixing branch (51) and the other half is a low-temperature heat transfer medium branch (52). The low-temperature mixing branch (51) includes an electric shut-off valve, a three-way valve, a low-temperature mixing water pump (511), an electric shut-off valve, and a check valve connected in sequence. The low-temperature heat transfer medium branch (52) includes an electric shut-off valve, a three-way valve, a low-temperature heat transfer medium pump (521), an electric shut-off valve, and a check valve connected in sequence.

2. The compressed air energy storage spherical tank transfer operation system according to claim 1, characterized in that: Electric shut-off valves are installed on the high-temperature inlet and high-temperature outlet of the thermal energy storage tank (1). Temperature sensor, pressure sensor and liquid level sensor are installed inside the thermal energy storage tank (1). Electric shut-off valves are installed on the low-temperature inlet and low-temperature outlet of the cold energy storage tank (2). Temperature sensor, pressure sensor and liquid level sensor are installed inside the cold energy storage tank (2). Electric shut-off valves are installed on the high-temperature inlet, high-temperature outlet, low-temperature inlet and low-temperature outlet of the bidirectional energy storage tank (3). Temperature sensor, pressure sensor and liquid level sensor are installed inside the bidirectional energy storage tank (3). Electromagnetic flow meters and temperature transmitters are installed at each branch connection of the low-temperature inlet main pipe, the high-temperature inlet main pipe, the low-temperature outlet main pipe and the high-temperature outlet main pipe, as well as in the inlet and outlet pipes of the heat exchanger, for detecting temperature and flow.

3. The compressed air energy storage spherical tank transfer operation system according to claim 1, characterized in that: The pressure regulating component (6) includes a pressure regulating pipe (61) connected to the inside of the cold storage tank (2). The pressure regulating pipe (61) is connected to two branches: pipe one (62) and pipe two (63). The ends of pipe one (62) and pipe two (63) are connected to the pressure regulating water tank (64). Pipe one (62) is equipped with a filter screen, a shut-off valve and a pressure regulating water pump. Pipe two (63) is equipped with a shut-off valve, a three-way valve and a filter screen.

4. A method for operating a compressed air energy storage spherical tank transfer system as described in any one of claims 1-3, characterized in that... The steps include the following: Step 1: Initially, the thermal energy storage tank (1) is empty, while the cold energy storage tank (2) and the bidirectional energy storage tank (3) are filled with cold water; Step 2: Confirm the prerequisites for any bidirectional energy storage tank (3) or cold energy storage tank (2), and check the temperature and pressure conditions; Step 3: When the preconditions are met, the forward energy storage is activated. Any bidirectional energy storage tank (3) or cold energy storage tank (2) sends cold water through the low-temperature heat medium water pump assembly (5) into the heat exchanger assembly to exchange heat into hot water and store it in the thermal energy storage tank (1). Step 4: After the thermal energy storage tank (1) is full, any cold energy storage tank (2) or bidirectional energy storage tank (3) filled with cold water will send the cold water through the low temperature heat medium water pump assembly (5) into the heat exchanger assembly to exchange heat into hot water and store it in the corresponding empty tank. Step 5: During the forward energy storage process, the wall temperature rise of the tank into which hot water is stored is detected. If it rises too quickly, the low temperature mixing branch (51) is used for temperature control. Step 6: Confirm the prerequisites for any bidirectional energy storage tank (3) or thermal energy storage tank (1), and check the temperature and pressure conditions; Step 7: When the preconditions are met, reverse energy release is activated, and any bidirectional energy storage tank (3) or thermal energy storage tank (1) sends hot water through the high-temperature heat medium water pump assembly (4) into the heat exchanger assembly to exchange heat into cold water and store it in the cold energy storage tank (2). Step 8: After the cold storage tank (2) is full, any hot storage tank (1) or bidirectional storage tank (3) filled with hot water can send the hot water through the high temperature heat medium water pump assembly (4) into the heat exchanger assembly to exchange heat into cold water and store it in the corresponding empty tank. Step 9: During the reverse energy release process, the wall temperature of the tank containing cold water is detected to drop. If the temperature drops too quickly, the high-temperature mixing branch (41) is used for temperature control.

5. The operating method of the compressed air energy storage spherical tank transfer system according to claim 4, characterized in that: In steps 2 and 6, the prerequisite for allowing forward energy storage is that the water temperature inside the tank is <80℃ and the pressure is <the upper limit of the constant pressure operating pressure. When the water temperature inside the tank is ≥240℃ or the pressure is ≥ the constant pressure water discharge opening pressure of any bidirectional energy storage tank (3) or cold energy storage tank (2), forward termination is triggered and the system switches to reverse. The prerequisite for allowing reverse energy release is that the water temperature inside the tank is >200℃ and the pressure is > the constant pressure water supply opening pressure of any bidirectional energy storage tank (3) or hot energy storage tank (1). When the water temperature inside the tank is ≤50℃ or the pressure is ≤ the lower limit of the constant pressure operating pressure, reverse termination is triggered and the system switches to forward.

6. The operating method of the compressed air energy storage spherical tank transfer system according to claim 5, characterized in that: When the pressure inside the tank does not meet the requirements, the pressure is regulated by the constant pressure component (6). Specifically, during positive energy storage, when the pressure inside the tank is greater than the constant pressure water discharge opening pressure, water is discharged from the cold energy storage tank (2) to the constant pressure water tank through pipe one at a constant pressure water discharge flow rate. During reverse energy release, when the pressure inside the tank is less than the constant pressure water supply opening pressure, the constant pressure water pump of pipe two is started to replenish water to the cold energy storage tank (2) at a certain flow rate. The details are as follows: The constant pressure water pump makeup water flow rate during reverse energy release is: ； in, This refers to the high-temperature water flow rate during reverse energy release under design conditions. The density of water at low temperatures; The density of water at high temperatures; This is the temperature compensation coefficient; The constant pressure water discharge flow rate during forward energy storage is: ； in, This refers to the high-temperature water flow rate during positive energy release under design conditions. Real-time pressure of the cold storage tank; This is the upper limit of the constant pressure operating pressure; For pressure safety margin; This is the pipeline flow loss coefficient.

7. The operating method of the compressed air energy storage spherical tank transfer system according to claim 4, characterized in that: The adjustment methods for steps 5 and 9 are as follows: The wall temperature rise rate during forward energy storage is controlled as follows: ； in, The specific heat capacity of high-temperature water at constant pressure; To determine the actual flow rate of high-temperature water injected; The actual temperature of the injected high-temperature water; The initial temperature of the tank wall; For the mass of the spherical tank wall; The specific heat capacity of the tank wall material; This is a correction factor for the heat exchange area; This is the temperature control coefficient for mixing. Control of the rate of decrease in wall temperature during reverse energy release: ； in, The specific heat capacity of water at constant pressure at low temperature; The actual flow rate of the injected low-temperature water; The actual temperature of the injected low-temperature water; This is the high-temperature mixing temperature adjustment coefficient; The corresponding valve opening degree for the mixing branch is corrected as follows: ； in, This refers to the initial opening degree of the mixing valve; This is the upper limit for the rate of change of wall temperature. This represents the actual rate of change of wall temperature.

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