Method for operating a liquid hydrogen cold energy recovery system and medium

Abstract

This application discloses an operation control method and medium for a liquid hydrogen cold energy recovery system, involving energy storage: Based on liquid hydrogen vaporization demand information and the operating status information of the liquid air energy storage subsystem, the target operating mode of the recovery system is determined; based on liquid hydrogen vaporization demand information, hydrogen outlet status information, and the segmented heat exchange temperature zones of liquid hydrogen along the heating direction, the target load allocation information of a three-stage series Brayton cycle is determined; based on the target operating mode and target load allocation information, the pressurized liquid hydrogen is controlled to sequentially exchange cold-end heat with the three-stage series Brayton cycle, and the cycle operating parameters of each stage of the Brayton cycle are adjusted; based on the compression heat storage information, ambient heat source temperature information, and the turbine inlet target temperature of each stage of the Brayton cycle, the coupled heat exchange network is controlled to perform dual-heat-source stepped heating of the working fluid of each stage of the Brayton cycle. This application achieves graded matching utilization of liquid hydrogen cold energy, LAES compression heat, and ambient heat, as well as stable and coordinated power generation of the combined system.

Description

Technical Field

[0001] This application relates to the field of energy storage, and in particular to an operation control method and medium for a liquid hydrogen cold energy recovery system. Background Technology

[0002] With the continuous increase in the installed capacity of renewable energy, the spatiotemporal mismatch between the intermittency and volatility of power sources such as wind and solar energy and load demand is becoming increasingly prominent, leading to a growing demand for large-scale, long-duration energy storage technologies in the power system. Liquid air energy storage technology, with its advantages of high energy density, fewer geographical limitations, long storage cycle, and suitability for large-scale deployment, is considered one of the important energy storage methods to support the high proportion of renewable energy consumption. Conventional liquid air energy storage systems typically store energy during the charging phase through air compression, cooling, and liquefaction, and generate electricity during the discharging phase through the heating, vaporization, and expansion of liquid air. However, in this process, it is often difficult to achieve a good quality match between the medium-to-high temperature heat of compression generated by air compression, the cold energy during the vaporization of liquid air, and the reheat demand on the discharge side, resulting in insufficient utilization of compression heat, limited system round-trip efficiency, and low levels of cascade utilization of cold and heat energy.

[0003] Meanwhile, with the development of the hydrogen energy industry and liquid hydrogen storage and transportation technology, liquid hydrogen, as an important form of large-scale, long-distance hydrogen energy transportation, releases a large amount of cryogenic cold energy during its regasification process at the receiving end. Liquid hydrogen is usually stored in a cryogenic environment of about 20K. During the process of heating and vaporizing to room temperature hydrogen, its cold energy release covers a wide temperature range of about 20K to 300K, characterized by high temperature grade, large temperature range, and strong recovery potential. In existing technologies, the cold energy from liquid hydrogen regasification is mostly directly discharged into the environment, or partially recovered only through single-stage heat exchange or single power cycle, which is difficult to adapt to the wide temperature range and multi-grade cold energy release characteristics of liquid hydrogen. Although there have been attempts to couple cryogenic cold energy with liquid air energy storage systems, the relevant solutions are mostly focused on the utilization of liquefied natural gas cold energy or cold energy in a single temperature range, making it difficult to achieve stable temperature and grade matching between liquid hydrogen and the circulating working fluid, environmental heat source, and liquid air energy storage compression heat within the wide temperature range of 20K to 300K.

[0004] Therefore, in the scenario of continuous regasification of liquid hydrogen and intermittent charge-discharge operation of liquid air energy storage, there are still problems such as inconsistent system operation sequence, large temperature range of liquid hydrogen cold energy release, dispersed demand for utilization of liquid air energy storage compression heat, and low temperature and limited heating capacity of environmental heat sources such as seawater. Existing single-stage cold energy recovery cycle or simple cold-heat coupling methods are difficult to coordinate and determine the system operation mode, load distribution of cold energy in different temperature ranges, and heating methods of each stage of the cycle working fluid according to the liquid hydrogen gasification demand, liquid air energy storage operation status, compression heat storage status, environmental heat source temperature, and hydrogen outlet status. This can easily lead to large liquid hydrogen cold energy loss, insufficient utilization of compression heat, limited Brayton cycle power generation efficiency, and inflexible joint system operation mode. Therefore, there is an urgent need for an operation control method that can take into account the wide temperature range cold energy release characteristics of liquid hydrogen and the intermittent operation characteristics of liquid air energy storage, so as to achieve graded matching utilization of liquid hydrogen cold energy, liquid air energy storage compression heat, and seawater environmental heat, switchable heating, and stable coordinated power generation. Summary of the Invention

[0005] This application aims to address how to coordinate and determine the system operation mode, three-stage Brayton cycle cold energy load distribution, and dual-heat source cascade heating method under the conditions of continuous regasification of liquid hydrogen and intermittent charge-discharge operation of liquid air energy storage, based on the cold energy release characteristics of liquid hydrogen over a wide temperature range, the state of LAES compression heat storage, and the heating capacity of the seawater environment, so as to achieve the graded matching utilization of liquid hydrogen cold energy, LAES compression heat, and environmental heat, and the stable and coordinated power generation of the combined system.

[0006] One aspect of this application provides an operation control method for a liquid hydrogen cold energy recovery system. The recovery system includes a liquid air energy storage subsystem, a liquid hydrogen cold energy recovery subsystem, and a coupled heat exchange network. The liquid hydrogen cold energy recovery subsystem includes a first-stage helium Brayton cycle, a second-stage neon Brayton cycle, and a third-stage nitrogen Brayton cycle connected in series along the liquid hydrogen heating direction.

[0007] Acquire system operating status information, including liquid hydrogen vaporization demand information, liquid air energy storage subsystem operating status information, compression heat storage information, ambient heat source temperature information, and hydrogen outlet status information;

[0008] Based on the liquid hydrogen vaporization demand information and the operating status information of the liquid air energy storage subsystem, the target operating mode of the recovery system is determined;

[0009] Based on the liquid hydrogen vaporization demand information, hydrogen outlet status information, and segmented heat exchange temperature zones of liquid hydrogen along the heating direction, the target load allocation information of the three-stage series Brayton cycle is determined.

[0010] Based on the target operating mode and target load allocation information, the pressurized liquid hydrogen is controlled to exchange cold end heat with the three-stage Brayton cycle in series, and the cycle operating parameters of each stage of the Brayton cycle are adjusted so that helium, neon and nitrogen can respectively recover the cold energy in the low temperature, medium temperature and high temperature sections of the liquid hydrogen regasification process.

[0011] Based on the information on compressible heat storage, ambient heat source temperature, and the turbine inlet target temperature of each stage of the Brayton cycle, the coupled heat exchange network is controlled to perform dual-heat-source stepped heating of the working fluid of each stage of the Brayton cycle.

[0012] Another aspect of this application provides a computer-readable storage medium that stores computer instructions that, when executed by a processor, implement an operation control method for a liquid hydrogen cold energy recovery system.

[0013] Compared to existing technologies, the advantages of this application are:

[0014] This application obtains system operating status information such as liquid hydrogen vaporization demand, liquid air energy storage subsystem operating status, compression heat storage, ambient heat source temperature, and hydrogen outlet status. Based on this information, it coordinates and determines the target operating mode, the target load allocation information of the three-stage series Brayton cycle, and the dual heat source cascade heating method. This allows the pressurized liquid hydrogen to sequentially exchange cold-end heat with helium, neon, and nitrogen Brayton cycles along the heating direction, thereby matching the liquid hydrogen cold energy in different temperature zones with the working fluids of different critical temperature characteristics. Simultaneously, it utilizes seawater ambient heat to preheat the working fluids of each stage of the Brayton cycle and performs supplementary heat control based on the LAES compression heat storage and the target inlet temperature of each turbine, achieving hierarchical coupling and dynamic matching between liquid hydrogen cold energy, LAES compression heat, and ambient heat. This can reduce the heat exchange temperature difference and cold energy loss during the wide-temperature-range regasification process of liquid hydrogen, improve the utilization rate of LAES compression heat and the power generation efficiency of each stage of the Brayton cycle, and enable the system to adapt to the timing difference between continuous regasification of liquid hydrogen and intermittent charging and discharging of liquid air energy storage, broaden the applicability of joint operation, independent gasification and independent energy storage and other operation modes, and improve the operation stability, energy utilization efficiency and collaborative power generation capability of the joint system. Attached Figure Description

[0015] This application will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0016] Figure 1 It is a deeply coupled integrated system of liquid hydrogen cold energy recovery and liquid air energy storage;

[0017] Figure 2This is an exemplary flowchart of an operation control method for a liquid hydrogen cold energy recovery system;

[0018] Figure 3 This is a temperature-entropy (TS) diagram of the charging phase of a LAES subsystem;

[0019] Figure 4 This is a temperature-entropy (TS) diagram of the discharge phase of a LAES subsystem;

[0020] Figure 5 This is a TS diagram of a three-stage Brayton cycle (helium, neon, nitrogen). Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following description, in conjunction with the accompanying drawings and embodiments, further illustrates this application. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0022] This application provides an operation control method for a liquid hydrogen cold energy recovery system. The liquid hydrogen cold energy recovery system includes a liquid air energy storage subsystem, a liquid hydrogen cold energy recovery subsystem, and a coupled heat exchange network. The liquid hydrogen cold energy recovery subsystem includes a first-stage helium Brayton cycle, a second-stage neon Brayton cycle, and a third-stage nitrogen Brayton cycle connected in series along the direction of liquid hydrogen heating.

[0023] This operation control method is particularly suitable for scenarios involving the coordinated operation of continuous regasification of liquid hydrogen and intermittent charging and discharging of liquid air energy storage. In this scenario, liquid hydrogen is typically stored at a cryogenic temperature of approximately 20K and releases cold energy across a wide temperature range of 20K to 300K during regasification. The liquid air energy storage subsystem operates intermittently, charging, shutting down, or discharging according to grid dispatch requirements, resulting in the supply of compression heat and the release of liquid hydrogen cold energy not always being synchronized in time. Furthermore, environmental heat sources such as seawater have low temperatures; if directly used as the primary heat source for the Brayton cycle, it is difficult to heat the working fluid to a high turbine inlet temperature. Conversely, directly using high-grade compression heat for cryogenic preheating easily leads to a waste of heat energy.

[0024] Based on this, this application achieves graded coupling, switchable heating, and coordinated power generation between liquid hydrogen cold energy, liquid air energy storage compression heat, and seawater environment heat by determining the system operation mode, the target load allocation information of the three-stage series Brayton cycle, and the dual heat source cascade heating method.

[0025] The liquid air energy storage subsystem, also known as the LAES subsystem, comprises two processes: a charging cycle and a discharging cycle. The charging cycle is used to compress, cool, liquefy, and store liquid air under off-peak electricity or surplus renewable power. The discharging cycle is used to pressurize, evaporate, reheat, and expand the liquid air to generate electricity during peak load periods. The liquid hydrogen cold energy recovery subsystem employs a three-stage series Brayton cycle, sequentially recovering and converting the cold energy over a wide temperature range during the liquid hydrogen regasification process into electrical energy using helium, neon, and nitrogen. The two subsystems can operate collaboratively under discharge conditions, or operate independently or switch between them depending on the liquid hydrogen vaporization requirements and the LAES operating status.

[0026] In one embodiment, such as Figure 1 As shown, the liquid hydrogen cold energy recovery system can be a three-stage series Brayton cycle coupled liquid air energy storage integrated system for liquid hydrogen cold energy recovery, namely the LH2-Brayton-LAES integrated system. This system includes a liquid air energy storage subsystem, a liquid hydrogen cold energy recovery subsystem, a coupled heat exchange network, and an intelligent controller.

[0027] like Figure 1 As shown, the liquid air energy storage subsystem includes an air compression liquefaction branch, a liquid air storage branch, and a liquid air energy release and power generation branch.

[0028] The air compression liquefaction branch includes a multi-stage air compressor driven by an electric motor, an interstage cooler, a heat exchanger branch for recovering compression heat, a cryogenic cooler, a cryogenic expander, and a gas-liquid separator. During the charging stage, air undergoes multi-stage compression, releasing compression heat through the interstage cooler. This compression heat is recovered and stored via the heat exchanger circuit. The cooled high-pressure air is further cooled and depressurized by the cryogenic cooler and cryogenic expander, and then enters the gas-liquid separator to separate into liquefied air. The unliquefied air is returned to the cryogenic cooling side for cold energy recovery.

[0029] The liquid air energy release power generation circuit includes a liquid air pump, an evaporative heat exchanger, a multi-stage air turbine, a reheater connected to the inlets of each stage air turbine, and a generator. During the discharge phase, liquid air is supplied from a liquid air storage tank, pressurized by a cryogenic pump, and then heated in the evaporative heat exchanger. The heated high-pressure air then sequentially enters the multi-stage air turbine for expansion and work, and is further heated between adjacent stages by the reheater, ultimately driving the generator to output electrical energy. The reheater can be connected to a compression heat storage unit to utilize the compression heat stored during the charging phase to reheat the high-pressure air.

[0030] The liquid hydrogen cold energy recovery subsystem includes a liquid hydrogen storage tank, a liquid hydrogen booster pump, a first-stage helium Brayton cycle, a second-stage neon Brayton cycle, and a third-stage nitrogen Brayton cycle arranged sequentially along the direction of liquid hydrogen heating, as well as a hydrogen output pipeline.

[0031] Each stage of the Brayton cycle includes a circulating compressor, a working fluid cold-end heat exchanger, a working fluid heater, a turbine expander, and a generator. The working fluid cold-end heat exchangers of each stage of the Brayton cycle are arranged in series along the direction of liquid hydrogen flow, allowing the pressurized liquid hydrogen to exchange cold-end heat with helium, neon, and nitrogen working fluids sequentially. The working fluid heaters of each stage of the Brayton cycle are connected to a coupled heat exchange network, ensuring that the circulating working fluid, after completing cold-end heat exchange, is heated to the corresponding turbine inlet target temperature before entering the turbine expander.

[0032] Specifically, the first-stage helium Brayton cycle is used to recover the low-temperature cold energy released by liquid hydrogen in the temperature range of 20K to 80K, the second-stage neon Brayton cycle is used to recover the medium-temperature cold energy released by liquid hydrogen in the temperature range of greater than 80K and less than or equal to 180K, and the third-stage nitrogen Brayton cycle is used to recover the high-temperature cold energy released by liquid hydrogen in the temperature range of greater than 180K and less than or equal to 300K.

[0033] When implementing the process, considering the heat exchanger pinch point temperature difference, the minimum operating temperature of the working fluid, and the adjustment margin of the heat exchange network, the actual temperature range covered by the helium Brayton cycle can be 20K to 80K, the actual temperature range covered by the neon Brayton cycle can be 50K to 260K, and the actual temperature range covered by the nitrogen Brayton cycle can be 130K to 340K.

[0034] The coupled heat exchange network includes a compression heat storage circuit, a seawater heat exchange branch, a Brayton cycle working fluid heating branch, a liquid air cooling recovery branch, and corresponding valves and flow regulation units.

[0035] The compression heat storage circuit is connected to the interstage cooler, discharge-side reheater, and working fluid heater of the three-stage Brayton cycle in the liquid air energy storage subsystem. It recovers the heat of air compression during the charging phase and supplies heat to the liquid air energy release and power generation branch and / or the three-stage Brayton cycle during the discharge phase or liquid hydrogen cold energy recovery phase. The seawater heat exchange branch is connected to the working fluid heating branches of each stage of the Brayton cycle, preheating the helium, neon, and nitrogen working fluids after cold-end heat exchange before heat transfer oil reheating. Thus, the Brayton cycle working fluid can be preheated to near ambient temperature using the seawater heat source, and then further heated to the turbine inlet target temperature using the compression heat of the liquid air energy storage subsystem.

[0036] In this application, the direction of liquid hydrogen heating refers to the flow and heat exchange direction of liquid hydrogen after it is output from the liquid hydrogen storage tank, pressurized by the liquid hydrogen booster pump, and gradually absorbs heat to vaporize and heat up to the target state of hydrogen outlet. Combined with... Figure 1Liquid hydrogen can start from a storage state of approximately 18.65 K and 0.1 MPa, and after being pressurized to 7.0 MPa to 7.2 MPa by a liquid hydrogen booster pump, it sequentially enters the first-stage helium Brayton cycle cold-end heat exchanger, the second-stage neon Brayton cycle cold-end heat exchanger, and the third-stage nitrogen Brayton cycle cold-end heat exchanger. After three stages of cold energy recovery, the hydrogen is finally heated to 260 K to 288 K and supplied to the user in a high-pressure, room-temperature hydrogen state of approximately 7.0 MPa.

[0037] In the heat exchange process described above, the three Brayton cycles each form a relatively independent closed loop. After being cooled by liquid hydrogen in the cold-end heat exchanger, the working fluid in each stage is pressurized by the circulating compressor, then heated to the target turbine inlet temperature by the seawater heat exchanger and / or the thermal oil heat exchanger. It then enters the turbine expander to do work and drive the corresponding generator to generate electricity. The working fluid at the turbine outlet returns to the cold-end heat exchanger to complete the closed loop.

[0038] Preferably, the helium Brayton cycle has a working fluid mass flow rate of 15.91 kg / s, a compression ratio of 5, a turbine inlet temperature of 474.20 K, and a power generation capacity of approximately 8.5 MW; the neon Brayton cycle has a working fluid mass flow rate of 130.11 kg / s, a compression ratio of 6, a turbine inlet temperature of 474.20 K, and a power generation capacity of approximately 12.0 MW; and the nitrogen Brayton cycle has a working fluid mass flow rate of 119.94 kg / s, a compression ratio of 4, a turbine inlet temperature of 474.20 K, and a power generation capacity of approximately 6.5 MW. The total power generation capacity of the three-stage Brayton cycle is approximately 27.0 MW.

[0039] The intelligent controller communicates with the liquid hydrogen booster pump, liquid air pump, multi-stage air compressor, multi-stage air turbine, Brayton cycle compressors at each stage, Brayton cycle turbines at each stage, bypass valves for the heat transfer oil heat exchange branch, control valves for the seawater heat exchange branch, and flow distribution valve groups. It is used to determine the target operating mode, the target load distribution information of the three-stage Brayton cycle, and the heating ratio of the dual heat sources based on the system operating status information, and to control the coupling heat exchange network to switch between seawater preheating, heat transfer oil supplementary heating, and seawater heating alone.

[0040] Example 1

[0041] In one embodiment, such as Figure 2 As shown, the operation control method includes the following steps.

[0042] S101, Obtain system operating status information.

[0043] Acquire system operating status information, including liquid hydrogen vaporization demand information, liquid air energy storage subsystem operating status information, compression heat storage information, ambient heat source temperature information, and hydrogen outlet status information.

[0044] The liquid hydrogen vaporization demand information can include whether there is a demand for liquid hydrogen vaporization, the liquid hydrogen regasification flow rate, the vaporization duration, and the load change trend. For example, in a 100MW system, the liquid hydrogen processing capacity can be 9.86 kg / s, approximately 50 tons / day.

[0045] The operational status information of the liquid air energy storage subsystem can include charging status, discharging status, shutdown status, charging power, discharging power, liquid air tank level, tank pressure, and grid dispatch instructions. For example, the charging power of the liquid air energy storage subsystem can be approximately 85MW, and the discharging power can be 100MW.

[0046] Information on compressible heat storage capacity can include the temperature, mass, available heat, remaining heat storage capacity, and heat output capacity of the heat transfer oil storage unit. For example, the heat transfer oil storage unit can use DowthermG as the heat storage medium, with a maximum temperature of approximately 479.23K or 507K, a heat storage capacity of approximately 200MWh, and a total capacity of approximately 450 tons.

[0047] Environmental heat source temperature information may include seawater temperature, seawater flow rate, seawater heat exchanger inlet and outlet temperatures, and ambient temperature. Hydrogen outlet status information may include hydrogen outlet target temperature, hydrogen outlet target pressure, actual outlet temperature, actual outlet pressure, and hydrogen quality requirements. For example, the hydrogen outlet target pressure may be 7.0 MPa, and the hydrogen outlet target temperature may be approximately 288 K.

[0048] Specifically, the intelligent controller can be configured with a network of temperature, pressure, and flow sensors to monitor in real time the liquid hydrogen vaporization rate, hydrogen outlet status, liquid air energy storage subsystem charge / discharge status, seawater temperature, and Brayton cycle operating parameters at each stage. Optionally, system operating status information can be acquired according to a preset sampling period, or it can be triggered when the liquid hydrogen vaporization demand changes, the liquid air energy storage subsystem switches between charge / discharge states, the compressed heat storage falls below a set threshold, or the seawater temperature changes beyond a set range.

[0049] S102, Determine the target operating mode of the recycling system.

[0050] Based on the liquid hydrogen vaporization demand information and the operational status information of the liquid air energy storage subsystem, the target operating modes of the recovery system are determined. The target operating modes include a combined operating mode, an independent vaporization mode, and an independent energy storage mode.

[0051] Specifically, when there is a demand for liquid hydrogen vaporization and the liquid air energy storage subsystem is in a discharge state, the target operating mode is determined to be the joint operating mode. In this mode, the liquid air energy storage subsystem releases liquid air and expands to generate electricity, while the liquid hydrogen cold energy recovery subsystem uses the cold energy from the re-vaporization of liquid hydrogen to drive the three-stage Brayton cycle power generation, and the compression heat in the thermal storage unit of the liquid air energy storage subsystem can serve as a supplementary heat source for the working fluid of each stage of the Brayton cycle.

[0052] When there is a demand for liquid hydrogen vaporization and the liquid air energy storage subsystem is in a shutdown or charging state, the target operating mode is determined to be the independent vaporization mode. In this mode, the liquid hydrogen cold energy recovery subsystem operates independently and utilizes seawater heat source or, when compression heat is available, auxiliary heating to meet the basic hydrogen supply needs of the hydrogen energy terminal and to generate Brayton power.

[0053] When there is no need for liquid hydrogen vaporization and the liquid air energy storage subsystem is in a charging or discharging state, the target operating mode is determined to be the independent energy storage mode. In this mode, the liquid hydrogen cold energy recovery subsystem is shut down, and the liquid air energy storage subsystem is controlled to perform either the air liquefaction energy storage process or the liquid air energy release power generation process.

[0054] S103, determine the target load allocation information for the three-stage series Brayton cycle.

[0055] Based on the liquid hydrogen vaporization demand information, hydrogen outlet status information, and segmented heat exchange temperature zones of liquid hydrogen along the heating direction, the target load allocation information for the three-stage series Brayton cycle is determined.

[0056] In this application, the segmented heat exchange temperature zone refers to dividing the heat exchange process of liquid hydrogen from a low-temperature liquid state to the target hydrogen outlet state into multiple temperature ranges based on the characteristic of the temperature gradually increasing during the regasification of liquid hydrogen.

[0057] Preferably, the heat exchange temperature zone of the low-temperature section corresponds to a temperature of 20K to 80K; the heat exchange temperature zone of the medium-temperature section corresponds to a temperature greater than 80K and less than or equal to 180K; and the heat exchange temperature zone of the high-temperature section corresponds to a temperature greater than 180K and less than or equal to 300K.

[0058] Specifically, the gasification conditions for the liquid hydrogen regasification process can be determined based on the liquid hydrogen vaporization demand information and the hydrogen outlet status information. These gasification conditions include the liquid hydrogen regasification flow rate, the target hydrogen outlet temperature, and the target hydrogen outlet pressure. For example, the liquid hydrogen regasification flow rate could be 9.86 kg / s, the target hydrogen outlet temperature could be 288 K, and the target hydrogen outlet pressure could be 7.0 MPa or 7.21 MPa. Based on the gasification conditions and the segmented heat exchange temperature zones, the recoverable cold energy corresponding to the low-temperature, medium-temperature, and high-temperature stages in the liquid hydrogen regasification process can be determined.

[0059] Optionally, the recoverable cold energy for each temperature zone can be determined based on the enthalpy change of liquid hydrogen or hydrogen gas within the corresponding temperature range and the regasification flow rate, for example, through the following relationship:

[0060] ;

[0061] in, For the i-th heat exchange temperature zone, the recoverable cold energy is... This represents the flow rate for liquid hydrogen regasification. This refers to the specific enthalpy of liquid hydrogen or hydrogen gas at the outlet state in this temperature range. This refers to the specific enthalpy of liquid hydrogen or hydrogen gas at the inlet state in this temperature range.

[0062] Furthermore, based on the recoverable cold energy, the critical temperatures of the working fluids in each stage of the Brayton cycle, and the matching relationship between each stage of the Brayton cycle and the segmented heat exchange temperature zones, the cold energy recovery load of each stage of the Brayton cycle is determined as target load allocation information.

[0063] The matching relationship is used to ensure that the working fluids of the Brayton cycle with critical temperatures ranging from low to high correspond to the low-temperature, medium-temperature, and high-temperature cold energy in the liquid hydrogen heating process.

[0064] Among them, helium has a critical temperature of approximately 5.20K, which is suitable for cold energy recovery in the low-temperature range of 20K to 80K; neon has a critical temperature of approximately 44.4K, which is suitable for cold energy recovery in the medium-temperature range; and nitrogen has a critical temperature of approximately 126.19K, which is suitable for cold energy recovery in the high-temperature range.

[0065] S104 controls the pressurized liquid hydrogen to exchange cold-end heat with the three-stage Brayton cycle in sequence.

[0066] Based on the target operating mode and target load allocation information, the pressurized liquid hydrogen is controlled to exchange cold-end heat with a three-stage Brayton cycle in series, and the cycle operating parameters of each stage of the Brayton cycle are adjusted so that helium, neon and nitrogen can respectively recover the cold energy in the low-temperature, medium-temperature and high-temperature sections of the liquid hydrogen regasification process.

[0067] In one specific embodiment, the liquid hydrogen is stored at a pressure of 0.1 MPa and a temperature of approximately 18.65 K, and then pressurized to 7.0 MPa to 7.2 MPa using a multi-stage pump. Subsequently, the high-pressure liquid hydrogen enters sequentially along the direction of liquid hydrogen heating into a helium Brayton cycle evaporator, a neon Brayton cycle evaporator, and a nitrogen Brayton cycle evaporator.

[0068] In the first-stage cold energy recovery process, high-pressure liquid hydrogen enters a helium Brayton cycle evaporator, absorbs heat and heats up to approximately 25.73 K. The helium working fluid is cooled to approximately 27.72 K, and then compressed, heated, and expanded to generate electricity. The working fluid mass flow rate of the helium Brayton cycle can be 15.91 kg / s, the compression ratio can be 5, the turbine inlet temperature can be 474.20 K, and the power generation capacity can be approximately 8.5 MW.

[0069] In the second-stage cold energy recovery process, the hydrogen gas continues to heat up to approximately 50K and enters the neon Brayton cycle evaporator. The neon working fluid is cooled to approximately 52K before being recycled for power generation. The working fluid mass flow rate of the neon Brayton cycle can be 130.11 kg / s, the compression ratio can be 6, the turbine inlet temperature can be 474.20K, and the power generation capacity can be approximately 12.0 MW.

[0070] In the third-stage cold energy recovery process, the hydrogen is further heated to approximately 130K and enters the nitrogen Brayton cycle evaporator. The nitrogen working fluid is cooled to approximately 137.67K before being recycled for power generation. The nitrogen Brayton cycle working fluid mass flow rate can be 119.94 kg / s, the compression ratio can be 4, the turbine inlet temperature can be 474.20K, and the power generation capacity can be approximately 6.5MW. Finally, the hydrogen can be heated to 260K to 288K and supplied to users at a high pressure of 7.0MPa and ambient temperature.

[0071] Optionally, the intelligent controller adjusts the start-stop combination and load distribution of the three-stage Brayton cycle according to the target load distribution information, so that the three-stage Brayton cycle can achieve 20% to 100% load regulation.

[0072] S105 controls the coupled heat exchange network to perform dual-heat-source stepped heating of each stage of the Brayton cycle working fluid.

[0073] Based on the information on compressed heat storage, ambient heat source temperature, and the turbine inlet target temperature of each stage of the Brayton cycle, the coupled heat exchange network is controlled to perform dual-heat-source stepped heating of the working fluid of each stage of the Brayton cycle.

[0074] Specifically, after the working fluids of each Brayton cycle complete the cold-end heat exchange with liquid hydrogen, they are first heated to the preheating target temperature using an ambient heat source, and then the preheated working fluids are heated to the corresponding turbine inlet target temperature using the compression heat of the liquid air energy storage subsystem.

[0075] Preferably, the ambient heat source is seawater. The preheating target temperature is determined based on the ambient heat source temperature information and the allowable pinch-point temperature difference of each stage of the Brayton cycle working fluid at the outlet of the ambient heat source heat exchanger. For example, when the seawater temperature and the allowable pinch-point temperature difference of the heat exchanger meet the requirements, each stage of the Brayton cycle working fluid can be preheated to 288K by seawater and then heated to 474.20K by heat transfer oil.

[0076] The heat supply of the liquid air energy storage subsystem is determined based on the information on the heat storage capacity and the corresponding target turbine inlet temperature.

[0077] Specifically, the available compressible heat supply of the liquid air energy storage subsystem is obtained; the target heat supply of each stage of the Brayton cycle is determined based on the turbine inlet target temperature of each stage of the Brayton cycle and the working fluid temperature after preheating by the seawater heat source; and the heat supply of the compressible heat to the working fluid of each stage of the Brayton cycle is determined based on the available compressible heat supply, the target heat supply, and the cold energy recovery load of each stage of the Brayton cycle.

[0078] In one embodiment, the temperature of the heat transfer oil circuit can be 479.23 K, and heat can be supplied to the three-stage Brayton cycle through heat transfer oil heat exchangers such as HX-7 to HX-18. The heat of compression can be distributed to the helium Brayton cycle, neon Brayton cycle, and nitrogen Brayton cycle in proportions of 3.66 MW, 5.98 MW, and 5.93 MW, respectively.

[0079] Optionally, the intelligent controller can also dynamically optimize the compression heat distribution ratio. The compression heat distribution ratio can be adjusted within the range of 33.86% to 40% to balance the LAES reheat demand and the Brayton cycle heating demand.

[0080] Optionally, the liquid hydrogen cold energy recovery subsystem is equipped with a bypass valve for the heat transfer oil heat exchange branch and a control valve for the seawater heat exchange branch. When the liquid air energy storage subsystem is shut down or has insufficient compression heat, the heat transfer oil heat exchange branch is closed and the seawater heat exchange branch is opened, allowing the three-stage Brayton cycle to operate using only seawater as a heat source. When the liquid air energy storage subsystem participates in coordinated operation, the heat supply ratio of heat transfer oil and seawater is adjusted through the valve group.

[0081] In the joint operation mode, the liquid air energy storage subsystem is controlled to be in a discharge state, and the liquid hydrogen cold energy recovery subsystem is controlled to be in an operating state, so that the pressurized liquid hydrogen exchanges cold end heat with the three-stage Brayton cycle in sequence along the heating direction; at the same time, the coupled heat exchange network is controlled to use seawater as a preheating heat source and the compression heat of the liquid air energy storage subsystem as a supplementary heat source to perform dual heat source stepped heating of the working fluid of each stage of the Brayton cycle.

[0082] In independent vaporization mode, the liquid air energy storage subsystem is controlled to be either shut down or charging, while the liquid hydrogen cold energy recovery subsystem is controlled to be in operation. Simultaneously, based on the compression heat storage information and the ambient heat source temperature information, the coupled heat exchange network is controlled to switch between compression heat-assisted heating and ambient heat source-only heating. This avoids the liquid hydrogen vaporization demand being limited by the LAES discharge timing.

[0083] Example 2

[0084] Based on a 100MW LAES discharge power, the liquid hydrogen supply capacity is 9.86kg / s, approximately 50 tons / day.

[0085] In this embodiment, the liquid air energy storage subsystem includes a multi-stage air compressor unit, a compression heat storage unit, a cryogenic liquefaction unit, a liquid air storage tank, a multi-stage expansion generator unit, and a cold storage recovery unit; the liquid hydrogen cold energy recovery subsystem includes a liquid hydrogen pressurization unit and a three-stage series Brayton cycle of helium, neon, and nitrogen; and a coupled heat exchange network is used to realize the hierarchical coupling of compression heat, cold energy, and ambient heat.

[0086] Combination Figure 3 and Figure 4 The temperature-entropy diagrams for the charging and discharging phases of the LAES subsystem are shown. During the charging phase, the LAES subsystem mainly undergoes air compression, interstage cooling, cryogenic liquefaction, and low-temperature expansion and separation processes. During the discharging phase, it mainly undergoes liquid air pumping pressurization, evaporation heating, multi-stage reheating, and expansion power generation processes.

[0087] Combination Figure 5 The temperature-entropy diagram of the three-stage Brayton cycle shown indicates that the helium, neon, and nitrogen cycles complete the compression, cooling, heating, and expansion processes in their respective closed-loop cycles to achieve the cascade recovery of cold energy from the regasification of liquid hydrogen.

[0088] Specifically, the multi-stage air compressor unit can employ a three-stage isentropic compressor and be equipped with interstage coolers (Cooler 1-3). The compression ratio increases progressively with each stage, resulting in a total compression ratio of approximately 13 MPa / 0.1 MPa = 130. The air mass flow rate during the charging phase can reach 309.59 kg / s, the compressor isentropic efficiency can be 80%, and the compressor outlet temperature can reach 507.55 K. The air temperature increases in each stage of the compressor, and then it is approximately isobarically cooled to approximately 303.68 K in the interstage cooler before entering the next stage of compression, thereby reducing compression power consumption and recovering heat from intermediate-temperature compression.

[0089] The compression heat storage unit uses DowthermG thermal oil as the heat storage medium. The maximum temperature of the thermal oil storage unit can reach approximately 479.23K to 507K, with a total thermal oil volume of approximately 450 tons and a heat storage capacity of approximately 200MWh. The cryogenic liquefaction unit includes a methanol / propane cascade cooling system (Cooler 4-5), a cryogenic turbine expander, and a gas-liquid separation flash tank. High-pressure air is cooled to 226.20K by methanol, then to 116.75K by propane, and further cooled by the return flow of unliquefied air. Subsequently, the cryogenic high-pressure air is expanded to 0.1MPa by the cryogenic turbine and enters the flash tank for gas-liquid separation, achieving a liquefaction rate of 70.90%. The separated liquid air is stored at a pressure of 0.1MPa and a temperature of approximately 79K or 79.43K. The liquid air storage tank adopts a vacuum multi-layer insulation structure, with a designed daily cooling loss rate of ≤0.5%, a maximum pressure of 0.12MPa, and a storage capacity designed for 8 hours of full-power discharge.

[0090] The multi-stage expander generator set can employ a three-stage air turbine and be equipped with a reheater (Heater 1-3). The expansion ratio is matched with the compression stage, with a total expansion ratio of approximately 12.9 MPa / 0.1 MPa = 129. The turbine entropy efficiency is 80%, and the turbine inlet temperature can be 474.23 K. During the discharge phase, the liquid air mass flow rate can be 219.54 kg / s. The liquid air is pressurized from 0.1 MPa and 78.99 K to 12.88 MPa by a cryogenic pump.

[0091] The pressurized liquid air flows sequentially through evaporator 1 and evaporator 2. Evaporator 1 recovers propane to 209.29 K, and evaporator 2 recovers methanol to 291 K. The released cold energy can be used to pre-cool the Brayton cycle working fluid, the inlet air of the liquefaction unit, or stored in the cold storage unit. Subsequently, the high-pressure air is heated to 474.23 K by a three-stage reheater, and then expanded to 0.1 MPa by a three-stage air turbine, outputting 100 MW of power. The exhaust temperature can reach 318.31 K.

[0092] In the liquid hydrogen cold energy recovery subsystem, the liquid hydrogen is stored at a pressure of 0.1 MPa and a temperature of approximately 18.65 K. It is then pressurized to 7.0 MPa to 7.2 MPa via a multi-stage pump, preferably to 7.21 MPa, and finally vaporized to 288 K. Combined with... Figure 5 The three-stage Brayton cycle TS diagram shown includes compression, cooling, heating and expansion processes in each stage of the cycle. However, due to the different thermal properties and critical temperatures of helium, neon and nitrogen, their cycles are distributed across different temperature ranges.

[0093] Specifically:

[0094] The first-stage helium Brayton cycle has a temperature range of 20K to 80K, a helium critical temperature of 5.20K, a mass flow rate of 15.91kg / s, a compression ratio of 5, and a turbine inlet temperature of 474.20K. It is used to recover the cold energy from the cryogenic stage of liquid hydrogen vaporization and has a power generation capacity of approximately 8.5MW.

[0095] The second-stage neon Brayton cycle has a temperature range of 50K to 260K, a neon critical temperature of 44.4K, a mass flow rate of 130.11kg / s, a compression ratio of 6, and a turbine inlet temperature of 474.20K. It is used to recover cold energy in the mid-temperature range and has a power generation capacity of approximately 12.0MW.

[0096] The third-stage nitrogen Brayton cycle operates in a temperature range of 130K to 340K, with a nitrogen critical temperature of 126.19K, a mass flow rate of 119.94 kg / s, a compression ratio of 4, and a turbine inlet temperature of 474.20K. It is used to recover cold energy from the high-temperature stage and generates approximately 6.5MW of electricity. The total power generation capacity of the three-stage Brayton cycle is approximately 27.0MW.

[0097] In the aforementioned three-stage Brayton cycle, the working fluid in each stage is cooled by liquid hydrogen in its corresponding cold-end heat exchanger, then pressurized by the cycle compressor, and further heated to the turbine inlet temperature by a seawater heat exchanger and a thermal oil heat exchanger before finally entering the turbine for expansion and power generation. Because the minimum temperature, compression ratio, working fluid flow rate, and turbine inlet temperature of the three-stage cycle are matched to different liquid hydrogen heating ranges, the problems of excessive temperature differences and increased heat loss that occur when a single cycle covers a wide temperature range can be avoided.

[0098] In this embodiment, the coupled heat exchange network includes a cold energy transfer path, a dual heat source heating module, and a flow distribution valve assembly. The cold energy transfer path may include:

[0099] The first-stage Brayton cycle is coupled with the LAES cold storage unit to pre-cool the air before it enters the liquefaction unit.

[0100] The second-stage Brayton cycle is coupled with the low-temperature cold energy recovery branch on the expansion side of the LAES to improve the low-temperature evaporative heat transfer matching.

[0101] The third-stage Brayton cycle is coupled to the LAES expansion side intermediate temperature heat or heat transfer oil circuit to further improve system efficiency.

[0102] The dual-heat-source heating module includes heat source A and heat source B. Heat source A is the LAES compression heat, and heat source B is seawater. The Brayton cycle working fluids at each stage are preferably preheated to 288K via a seawater heat exchanger before turbine expansion and power generation, and then heated to 474.20K via a thermal oil heat exchanger.

[0103] During operation, the intelligent controller optimizes the operating mode based on grid dispatch instructions, hydrogen demand forecasts, and real-time electricity prices. During nighttime or periods of surplus power, a charging phase can be implemented, utilizing surplus grid power to drive the LAES three-stage air compressor. The price of surplus grid power can be $41.7 per megawatt-hour. During this phase, the Brayton cycle may not operate, and liquid hydrogen regasification can be carried out independently or suspended based on end-user hydrogen demand.

[0104] During the liquid hydrogen vaporization and cold energy recovery stage, liquid hydrogen is output from the storage tank and pressurized by a multi-stage pump. Along the direction of liquid hydrogen temperature rise, it sequentially exchanges cold-end heat with the first-stage helium Brayton cycle, the second-stage neon Brayton cycle, and the third-stage nitrogen Brayton cycle. Before turbine expansion, the working fluid in each Brayton cycle is preheated to 288K by seawater and then heated to 474.20K by LAES compressed heat transfer oil.

[0105] During peak power periods, a discharge phase can be implemented, where liquid air is pressurized by a cryogenic pump, evaporates, reheats, and expands to generate electricity. If there is also a demand for liquid hydrogen vaporization, the target operating mode is determined to be a combined operating mode, where LAES discharge, liquid hydrogen vaporization, and Brayton cycle power generation occur simultaneously. If there is only a demand for liquid hydrogen vaporization and the LAES is in a shutdown or charging state, the target operating mode is determined to be an independent vaporization mode. If there is no demand for liquid hydrogen vaporization and the LAES is in a charging or discharging state, the target operating mode is determined to be an independent energy storage mode.

[0106] Through the above control measures, at a LAES discharge power scale of 100MW, the round-trip efficiency of the integrated system can reach 75.91%, which is 20.93 percentage points higher than the 54.98% of a single LAES system; in terms of relative improvement, it can be increased by 38.1%. Among them, the charging power is about 85MW, the discharging power is 100MW, and the total Brayton cycle power generation is about 27MW.

[0107] Example 3

[0108] In one embodiment, sensitivity analysis can also be performed on the efficiency of key equipment, the performance of heat exchangers, and the cold loss of storage tanks to determine the constraints of the system operation control method in engineering deployment.

[0109] Regarding the efficiency of critical equipment, if the isentropic efficiency of the compressor increases from 80% to 92%, the LCOE can decrease from $84.71 / MWh to $81.72 / MWh, and the NPV can increase from $193 million to $194.13 million. If the isentropic efficiency of the turbine increases from 80% to 92%, the LCOE can decrease from $91.72 / MWh to $81.12 / MWh, and the NPV can increase from $155.6 million to $198.18 million.

[0110] Regarding heat exchanger performance, if the evaporator pinch-point temperature difference increases from 2K to 8K, the LCOE can slightly increase from $81.99 / MWh to $82.49 / MWh. If the minimum propane temperature varies within the range of 86K to 95K, the LCOE can remain stable between $82.29 / MWh and $82.48 / MWh, indicating that the system design has good robustness.

[0111] Regarding tank cooling losses, if the daily cooling loss rate increases from 0% to 5%, the integrated system's RTE can decrease from 75.91% to 67.07%, a reduction of 8.84%; NPV can decrease from US$194.69 million to US$152.09 million, a reduction of 21.9%; and LCOE can increase from US$82.27 / MWh to US$91.42 / MWh. In contrast, under the same cooling loss conditions, the RTE of an independent LAES system can decrease from 54.98% to 47.89%, a reduction of 7.09%. Therefore, liquid air storage tanks preferably adopt a vacuum multi-layer insulation structure, and the design daily cooling loss rate should be controlled at ≤0.5%.

[0112] Through the above implementation methods, this application can coordinate and determine the target operating mode, the target load allocation information of the three-stage series Brayton cycle, and the dual-heat-source cascade heating method based on the liquid hydrogen vaporization demand information, the operating status information of the liquid air energy storage subsystem, the compression heat storage information, the ambient heat source temperature information, and the hydrogen outlet status information. Thus, the pressurized liquid hydrogen can sequentially exchange cold-end heat with helium, neon, and nitrogen Brayton cycles along the heating direction, matching the 20K to 300K wide-temperature range cold energy with the cycle working fluids of different critical temperature characteristics. Simultaneously, after completing the cold-end heat exchange, the working fluids of each stage of the Brayton cycle are first preheated using seawater ambient heat, and then supplemented with LAES compression heat to reach the turbine inlet target temperature, thereby reducing the grade loss caused by directly using high-grade compression heat for low-temperature preheating.

[0113] Compared to traditional single-stage cold energy recovery methods, this application utilizes a three-stage Brayton cycle (helium-neon-nitrogen) to recover cold energy from liquid hydrogen over a wide temperature range of 20K to 300K, improving efficiency by 15% to 20%. Combined with dual-heat source optimization, the system's round-trip efficiency can be increased from 54.98% with a single LAES to 75.91%. Furthermore, the dual-heat source design allows the liquid hydrogen vaporization subsystem to operate independently, adapting to different hydrogen energy demands and grid dispatch. The three-stage Brayton cycle can be started and stopped in combination according to load demand, achieving load regulation from 20% to 100%. This system is suitable for power levels of 100MW and above, and can be used for the coordinated deployment of port liquid hydrogen receiving stations and grid-side energy storage, with scalability up to GWh-level energy storage capacity.

[0114] This application also provides a computer-readable storage medium. The computer-readable storage medium can be any available medium capable of being stored by a computing device, or a data storage device such as a data center containing one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive). The computer-readable storage medium includes instructions that instruct the computing device to execute a method for controlling the operation of a liquid hydrogen cold energy recovery system.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of this application.

Claims

1. A method for operating and controlling a liquid hydrogen cold energy recovery system, the recovery system comprising a liquid air energy storage subsystem, a liquid hydrogen cold energy recovery subsystem, and a coupled heat exchange network, wherein the liquid hydrogen cold energy recovery subsystem comprises a first-stage helium Brayton cycle, a second-stage neon Brayton cycle, and a third-stage nitrogen Brayton cycle connected in series along the direction of liquid hydrogen heating, characterized in that, include: Acquire system operating status information, including liquid hydrogen vaporization demand information, liquid air energy storage subsystem operating status information, compression heat storage information, ambient heat source temperature information, and hydrogen outlet status information; Based on the liquid hydrogen vaporization demand information and the operating status information of the liquid air energy storage subsystem, the target operating mode of the recovery system is determined; Based on the liquid hydrogen vaporization demand information, hydrogen outlet status information, and segmented heat exchange temperature zones of liquid hydrogen along the heating direction, the target load allocation information of the three-stage series Brayton cycle is determined. Based on the target operating mode and target load allocation information, the pressurized liquid hydrogen is controlled to exchange cold end heat with the three-stage Brayton cycle in series, and the cycle operating parameters of each stage of the Brayton cycle are adjusted so that helium, neon and nitrogen can respectively recover the cold energy in the low temperature, medium temperature and high temperature sections of the liquid hydrogen regasification process. Based on the information on compressed heat storage, ambient heat source temperature, and the turbine inlet target temperature of each stage of the Brayton cycle, the coupled heat exchange network is controlled to perform dual-heat-source stepped heating of the working fluid of each stage of the Brayton cycle.

2. The operation control method for the liquid hydrogen cold energy recovery system according to claim 1, characterized in that: The target operating modes include joint operation mode, independent gasification mode, and independent energy storage mode; When there is a demand for liquid hydrogen vaporization and the liquid air energy storage subsystem is in a discharge state, the target operating mode is determined to be the joint operating mode. When there is a demand for liquid hydrogen vaporization and the liquid air energy storage subsystem is in a shutdown or charging state, the target operating mode is determined to be the independent vaporization mode. When there is no need for liquid hydrogen vaporization and the liquid air energy storage subsystem is in a charging or discharging state, the target operating mode is determined to be the independent energy storage mode. In the independent energy storage mode, the liquid hydrogen cold energy recovery subsystem is shut down, and the liquid air energy storage subsystem is controlled to perform the air liquefaction energy storage process or the liquid air energy release power generation process.

3. The operation control method for the liquid hydrogen cold energy recovery system according to claim 2, characterized in that: When the target operating mode is the combined operating mode, the liquid air energy storage subsystem is controlled to be in a discharge state, and the liquid hydrogen cold energy recovery subsystem is controlled to be in an operating state, so that the pressurized liquid hydrogen can exchange cold end heat with the first, second and third Brayton cycles in sequence along the liquid hydrogen heating direction. Furthermore, based on the information on the compressible heat storage, the ambient heat source temperature, and the turbine inlet target temperature of each stage of the Brayton cycle, the coupled heat exchange network is controlled to use the ambient heat source as the preheating heat source and the compressible heat of the liquid air energy storage subsystem as the supplementary heat source to perform dual-heat-source stepped heating of the Brayton cycle working fluid after the cold end heat exchange is completed.

4. The operation control method for the liquid hydrogen cold energy recovery system according to claim 2, characterized in that: When the target operating mode is independent gasification mode, the liquid air energy storage subsystem is controlled to be in a shutdown or charging state, and the liquid hydrogen cold energy recovery subsystem is controlled to be in an operating state, so that the pressurized liquid hydrogen can exchange cold end heat with the first, second and third Brayton cycles in sequence along the liquid hydrogen heating direction. Furthermore, based on the information on the compressible heat storage capacity and the ambient heat source temperature, the coupled heat exchange network is controlled to switch between the compressible heat-assisted heating mode and the ambient heat source-only heating mode.

5. The operation control method for the liquid hydrogen cold energy recovery system according to any one of claims 2 to 4, characterized in that: Based on the information on compressible heat storage, ambient heat source temperature, and the turbine inlet target temperature of each stage of the Brayton cycle, the coupled heat exchange network is controlled to perform dual-heat-source stepped heating of the working fluid in each stage of the Brayton cycle, including: After completing the cold-end heat exchange with liquid hydrogen, the working fluids of each stage of the Brayton cycle are first heated to the preheating target temperature using an ambient heat source, and then the preheated working fluids of each stage of the Brayton cycle are heated to the corresponding turbine inlet target temperature using the compression heat of the liquid air energy storage subsystem, so as to reduce the grade loss of compression heat used for low-temperature preheating. The preheating target temperature is determined based on the ambient heat source temperature information and the allowable pinch temperature difference of each Brayton cycle working fluid at the outlet of the ambient heat source heat exchanger. The heat supply of the liquid air energy storage subsystem to the working fluid of each stage of the Brayton cycle is determined based on the information on the heat storage capacity of the liquid air and the corresponding turbine inlet target temperature.

6. The operation control method for the liquid hydrogen cold energy recovery system according to claim 5, characterized in that: The environmental heat source is seawater.

7. The operation control method for the liquid hydrogen cold energy recovery system according to claim 6, characterized in that: The heat supply from the compression heat of the liquid air energy storage subsystem to the working fluids of each stage of the Brayton cycle is determined based on the compression heat storage information and the corresponding turbine inlet target temperature, including: Obtain available compressible heat supply from the liquid air energy storage subsystem; The target heat compensation for each stage of the Brayton cycle is determined based on the turbine inlet target temperature and the working fluid temperature after preheating by the seawater heat source. Based on the available compressible heat supply, target heat replenishment, and cold energy recovery load of each stage of the Brayton cycle, determine the heat supply of the liquid air energy storage subsystem to the working fluid of each stage of the Brayton cycle.

8. The operation control method for the liquid hydrogen cold energy recovery system according to claim 6, characterized in that: Based on the liquid hydrogen vaporization demand information, hydrogen outlet status information, and segmented heat transfer temperature zones of liquid hydrogen along the heating direction, the target load allocation information for the three-stage series Brayton cycle is determined, including: Based on the liquid hydrogen vaporization demand information and hydrogen outlet status information, determine the vaporization condition information of the liquid hydrogen regasification process; the vaporization condition information includes liquid hydrogen regasification flow rate, hydrogen outlet target temperature, and hydrogen outlet target pressure. Based on the gasification condition information and the segmented heat exchange temperature zones, the recoverable cold energy corresponding to the low temperature, medium temperature and high temperature sections in the liquid hydrogen regasification process is determined. Based on the recoverable cold energy, the critical temperatures of the working fluids in each Brayton cycle, and the matching relationship between each Brayton cycle and the segmented heat exchange temperature zone, the cold energy recovery load of each Brayton cycle is determined as the target load allocation information for each Brayton cycle. The matching relationship is used to ensure that the working fluids of the Brayton cycle with critical temperatures ranging from low to high correspond to the low-temperature, medium-temperature, and high-temperature cold energy in the liquid hydrogen heating process.

9. The operation control method for the liquid hydrogen cold energy recovery system according to claim 8, characterized in that: The heat exchange temperature zone in the low-temperature section corresponds to a temperature of 20K to 80K; The heat exchange temperature zone in the medium temperature range corresponds to a temperature greater than 80K and less than or equal to 180K; The heat exchange temperature zone in the high-temperature section corresponds to a temperature greater than 180K and less than or equal to 300K.

10. A computer-readable storage medium storing computer instructions that, when executed by a processor, implement the method as described in any one of claims 1 to 9.

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