Oxygen-nitrogen liquid conversion and energy storage system of air separation device under peak valley electricity condition

Abstract

The invention discloses an oxygen-nitrogen liquid conversion and energy storage system of an air separation device under a peak-valley electricity condition, and relates to the technical field of gas separation, and the oxygen-nitrogen liquid conversion and energy storage system comprises a nitrogen compression system which comprises a nitrogen compressor; the liquid oxygen vaporization system comprises a vaporization heat exchanger, a liquid oxygen pump, a liquid nitrogen throttle valve and a liquid nitrogen vacuum tank; the oxygen liquefaction system comprises a liquefaction heat exchanger, a liquid nitrogen pump, a nitrogen expansion machine, a liquid oxygen throttle valve and a liquid oxygen vacuum tank; the solid-state bed energy storage system comprises a solid-state bed regenerator and a nitrogen circulating fan; the nitrogen circulation refrigeration system comprises a circulation nitrogen compressor, a nitrogen pressurization expansion machine pressurization section and a nitrogen pressurization expansion machine expansion section; and a control unit. The oxygen liquefaction and solid-state bed energy storage system is started in the peak electricity period to recover surplus oxygen, and the nitrogen compression, liquid oxygen vaporization and solid-state bed energy storage system is started in the valley electricity period to release and store oxygen, so that the cooperative capability of an air separation device and a downstream gas utilization device is improved, and efficient utilization of energy and stable operation of the system are realized.

Description

Technical Field

[0001] This invention relates to the field of gas separation technology, and in particular to an oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions. Background Technology

[0002] In existing technologies, air separation units have the following shortcomings when operating under peak-valley electricity price fluctuations: Oxygen venting during peak power periods: Downstream gas-consuming units reduce their load or even shut down, so the oxygen produced by the air separation unit cannot be consumed and can only be vented, resulting in resource waste and reduced energy efficiency.

[0003] Insufficient gas supply during off-peak hours: Downstream gas demand has increased significantly, and even when the air separation unit is operating at full capacity, it is still difficult to meet the gas demand, which restricts production stability.

[0004] Insufficient operational flexibility: the air separation unit is difficult to start and stop, and its response to large load fluctuations is inflexible, making it unable to effectively match downstream gas demand. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention provides an oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions, comprising: A nitrogen compression system, which includes a nitrogen compressor; A liquid oxygen vaporization system, which includes a vaporization heat exchanger, a liquid oxygen pump, a liquid nitrogen throttle valve, and a liquid nitrogen vacuum tank; An oxygen liquefaction system, comprising a liquefaction heat exchanger, a liquid nitrogen pump, a nitrogen expander, a liquid oxygen throttling valve, and a liquid oxygen vacuum tank; Solid-state bed energy storage system, which includes a solid-state bed accumulator and a nitrogen circulation fan; A nitrogen circulation refrigeration system, comprising a circulating nitrogen compressor, a nitrogen booster expander pressurization section, and a nitrogen booster expander expansion section; The control unit is used to control the various systems to operate alternately during peak and off-peak electricity periods based on peak and off-peak electricity price signals and historical oxygen supply and demand data.

[0006] Preferably, the nitrogen compressor is connected to a vaporization heat exchanger; The vaporization heat exchanger is connected to a liquid nitrogen throttling valve, which has one path returning to the vaporization heat exchanger and the other path connected to the liquid nitrogen vacuum tank. The liquid nitrogen vacuum tank is connected to a liquid nitrogen pump.

[0007] Preferably, the liquid nitrogen pump is connected to a liquefaction heat exchanger; The liquefaction heat exchanger is connected to the nitrogen expander, and the outlet of the expander flows back to the liquefaction heat exchanger. The liquefaction heat exchanger is connected to the liquid oxygen throttle valve; The liquid oxygen throttling valve is connected to the liquid oxygen vacuum tank; The liquid oxygen vacuum tank is connected to the liquid oxygen pump; The liquid oxygen pump is connected to the vaporization heat exchanger.

[0008] Preferably, the liquefaction heat exchanger is connected to the circulating nitrogen compressor, the circulating nitrogen compressor is connected to the pressurization section of the nitrogen booster expander, the pressurization section of the nitrogen booster expander is connected to the liquefaction heat exchanger (CONEH), the liquefaction heat exchanger is connected to the expansion section of the nitrogen booster expander, and the expansion section of the nitrogen booster expander is in turn connected to the liquefaction heat exchanger.

[0009] Preferably, the nitrogen circulating fan has two independent circulation paths, which are switched and controlled by valves, wherein: In the first path, the outlet of the nitrogen circulating fan is connected to the cold end inlet of the solid bed accumulator, and the cold end outlet of the solid bed accumulator is connected to the nitrogen channel inlet of the vaporization heat exchanger. After the nitrogen release is completed, it returns to the atmospheric pressure nitrogen pipeline. In the second path, the outlet of the nitrogen circulating fan is connected to the inlet of the nitrogen precooling channel of the liquefied heat exchanger. The cooled nitrogen enters the solid bed accumulator for cold storage and then returns to the atmospheric pressure nitrogen pipeline.

[0010] As a preferred option, it also includes: The data acquisition module is used to collect real-time data on oxygen production, liquid oxygen storage, downstream gas load, pipeline pressure, temperature, and time-of-use electricity price signals. Historical database is used to store oxygen supply and demand fluctuation data, system operation energy efficiency data, and operation strategy records corresponding to electricity price periods for at least one year; The predictive analysis module uses time series analysis and machine learning algorithms to predict oxygen demand trends, electricity price changes during the next 24 hours to a week based on historical data and real-time collected data, and the optimal energy storage / release strategy for the system, and outputs control suggestions to the control unit.

[0011] Preferably, the control unit dynamically adjusts the speed of the liquid oxygen pump and liquid nitrogen pump, the opening degree of the liquid oxygen throttle valve and liquid nitrogen throttle valve, the operating frequency of the nitrogen compressor, and the start / stop and airflow of the nitrogen circulation fan according to the control suggestions output by the predictive analysis module.

[0012] Preferably, during the operation of the control unit: During peak power periods: the oxygen liquefaction system and solid bed energy storage system are started. The excess oxygen generated by the air separation unit is cooled and liquefied by the liquefaction heat exchanger and stored in the liquid oxygen vacuum tank. At the same time, the cold energy is stored in the solid bed cold accumulator through the nitrogen circulation fan. During off-peak electricity hours: The nitrogen compression system and liquid oxygen vaporization system are started. The stored liquid oxygen is pressurized by the liquid oxygen pump and sent to the vaporization heat exchanger for vaporization, which then replenishes the low-pressure oxygen pipeline network. At the same time, the solid bed accumulator releases cold energy to assist vaporization.

[0013] As a preferred option, it also includes historical data comparison and analysis, which automatically compares the differences in oxygen recovery rate, energy consumption, and gas supply stability between the current cycle and the same period in history after each operation cycle. Combined with the output of the predictive analysis module, it dynamically adjusts the oxygen remaining threshold for liquefaction start-up, the timing and flow rate of vaporization release, and the cold energy distribution ratio of the solid bed accumulator in the next cycle.

[0014] The present invention has at least the following beneficial effects: Compared with existing technologies, this system significantly improves the overall operational efficiency of air separation units under peak and off-peak electricity conditions. Specifically, during peak electricity periods when electricity prices are high, the system liquefies, recovers, and stores excess oxygen from the air separation unit due to insufficient downstream demand, greatly improving the utilization rate of oxygen resources and effectively avoiding resource waste caused by direct venting. Simultaneously, during off-peak electricity periods when electricity prices are low or during peak gas consumption periods, the system can liquefy the stored liquid oxygen and replenish the gas supply network, thereby reliably ensuring the gas demand of downstream users and the continuity of production.

[0015] Furthermore, by combining solid-bed energy storage technology with time-of-use pricing, the system achieves cascaded energy utilization and peak shaving, reducing overall operating costs and improving economic efficiency. In terms of operational stability, the system smooths out load fluctuations in the air separation unit by storing and buffering external oxygen, which is conducive to achieving continuous and stable operation of the unit. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0017] Figure 1 This is a structural diagram of an oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions, as provided in Embodiment 1 of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0020] Example 1

[0021] This embodiment provides an oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions, such as... Figure 1 As shown, it includes: A nitrogen compression system, which includes a nitrogen compressor NC; The liquid oxygen vaporization system includes a vaporization heat exchanger EVAEH, a liquid oxygen pump OP, a liquid nitrogen throttle valve NV, and a liquid nitrogen vacuum tank NT; The oxygen liquefaction system includes a liquefaction heat exchanger (CONEH), a liquid nitrogen pump (NP), a nitrogen expander (ET), a liquid oxygen throttle valve (OV), and a liquid oxygen vacuum tank (OT). Solid-state bed energy storage system, which includes a solid-state bed accumulator (CSD) and a nitrogen circulation fan (NF); The nitrogen circulation refrigeration system includes a circulating nitrogen compressor (RNC), a nitrogen booster expander (ETC), and a nitrogen booster expander (ET). The control unit is used to control the various systems to operate alternately during peak and off-peak electricity periods based on peak and off-peak electricity price signals and historical oxygen supply and demand data; The nitrogen compressor NC is connected to the vaporization heat exchanger EVAEH; The vaporization heat exchanger EVAEH is connected to the liquid nitrogen throttling valve NV, which has one return path to the vaporization heat exchanger and another path to the liquid nitrogen vacuum tank NT. The liquid nitrogen vacuum tank NT is connected to the liquid nitrogen pump NP; The liquid nitrogen pump NP is connected to the liquefaction heat exchanger CONEH; The liquefaction heat exchanger CONEH is connected to the nitrogen expander ET, and the expander outlet flows back to the liquefaction heat exchanger; The liquefaction heat exchanger CONEH is connected to the liquid oxygen throttle valve OV; The liquid oxygen throttle valve OV is connected to the liquid oxygen vacuum tank OT; The liquid oxygen vacuum tank OT is connected to the liquid oxygen pump OP; The liquid oxygen pump OP is connected to the vaporization heat exchanger EVAEH.

[0022] The liquefaction heat exchanger (CONEH) is connected to the circulating nitrogen compressor (RNC). The circulating nitrogen compressor (RNC) is connected to the nitrogen booster expander (ETC). The nitrogen booster expander (ETC) is connected to the liquefaction heat exchanger (CONEH). The liquefaction heat exchanger (CONEH) is connected to the nitrogen booster expander (ET). The nitrogen booster expander (ET) is then connected to the liquefaction heat exchanger (CONEH). Specifically, the system comprises four core components: a nitrogen compression system, a liquid oxygen vaporization system, an oxygen liquefaction system, and a solid-bed energy storage system. These subsystems are interconnected and coordinated through specific processes to achieve oxygen recovery and energy redistribution under peak-valley electricity price differences. Specifically, during peak grid load periods and periods of higher electricity prices, the system automatically activates the oxygen liquefaction system and the solid-bed energy storage system. At this time, excess gaseous oxygen from the air separation unit enters the liquefaction heat exchanger, is cooled and liquefied by cryogenic liquid nitrogen pumped by a liquid nitrogen pump, and is converted into liquid oxygen, which is then stored in a liquid oxygen vacuum tank, thus achieving oxygen recovery and storage. Simultaneously, the solid-bed energy storage system uses a nitrogen circulation fan to drive nitrogen to circulate between the liquefaction heat exchanger and the solid-bed cold storage unit, storing the excess cooling energy generated during liquefaction as sensible heat in the cold storage material, completing the "cooling" process. During off-peak electricity hours when grid load is low and electricity prices are low, the system switches to a coordinated operation mode of the nitrogen compression system, liquid oxygen vaporization system, and solid bed energy storage system. Stored liquid oxygen is pressurized by a liquid oxygen pump and sent to the vaporization heat exchanger, where it exchanges heat with high-pressure nitrogen from the nitrogen compressor. The liquid oxygen absorbs heat and vaporizes into gaseous oxygen, which is then supplied to the downstream gas supply network. Simultaneously, the solid bed energy storage system switches to a "cooling" mode, where stored cold energy is extracted through nitrogen circulation and sent to the vaporization heat exchanger as an auxiliary cold source to improve vaporization efficiency, thereby reducing the load and energy consumption of the nitrogen compressor. Through this time-sharing strategy and multi-system coupled operation, the system achieves periodic allocation of oxygen recovery and release during peak electricity hours and gas supply replenishment during off-peak hours. This effectively connects the air separation unit's production with downstream gas demand, improving energy utilization efficiency and the system's economic efficiency and stability.

[0023] During off-peak electricity hours, when liquid oxygen is vaporized, atmospheric pressure nitrogen from the pipeline is pressurized to a certain pressure by the nitrogen compressor NC and then enters the vaporization heat exchanger EVAEH. The liquid oxygen is pressurized by the liquid oxygen pump OP from the liquid oxygen vacuum tank OT and exchanges heat. After absorbing heat and vaporizing, the liquid oxygen is sent to the low-pressure oxygen pipeline network. The pressurized nitrogen is cooled and liquefied, and then throttled by the liquid nitrogen throttle valve NV. The gas phase flows back to the vaporization heat exchanger EVAHE for reheating and is then sent to the low-pressure nitrogen pipeline network. The liquid phase enters the liquid nitrogen vacuum tank NT for storage.

[0024] Atmospheric nitrogen from the pipeline is pressurized by the nitrogen circulation fan NF and enters the solid bed accumulator SCD to be cooled to a low temperature. Then it enters the vaporization heat exchanger EVAEH to release the cold energy and is reheated before being sent to the atmospheric nitrogen pipeline.

[0025] Low-pressure oxygen from the pipeline enters the liquefaction heat exchanger (CONEH) and exchanges heat with liquid nitrogen from the liquid nitrogen vacuum tank (NT). The low-pressure oxygen is cooled and liquefied, and after passing through the liquid oxygen throttling valve (OV), it is sent to the liquid oxygen vacuum tank (OT). A portion of the liquid oxygen is sent out as liquid oxygen product. The liquid nitrogen is vaporized and reheated before being sent to the low-pressure nitrogen pipeline. In the nitrogen circulation refrigeration system, atmospheric pressure nitrogen from the pipeline and the liquefaction heat exchanger (CONEH) is pressurized by the circulating nitrogen compressor (RNC) and enters the nitrogen booster expander (ETC) for further pressurization. It then enters the liquefaction heat exchanger (CONEH) for cooling. After cooling, the pressurized nitrogen is extracted from the middle of the liquefaction heat exchanger (CONEH) and sent to the nitrogen booster expander (ET) for expansion and refrigeration. The expanded low-temperature nitrogen is reheated by the liquefaction heat exchanger (CONEH) and then sent to the circulating nitrogen compressor (RNC).

[0026] Atmospheric nitrogen from the pipeline is pressurized by the nitrogen circulation fan NF, enters the liquefaction heat exchanger CONEH to be cooled to a low temperature, then enters the solid bed accumulator SCD to store the cold energy, and after reheating, it is sent to the atmospheric nitrogen pipeline.

[0027] Example 2

[0028] Based on the above embodiment one, the nitrogen circulating fan NF in this embodiment has two independent circulation paths, which are switched and controlled by valves, wherein: In the first path, the outlet of the nitrogen circulation fan NF is connected to the cold end inlet of the solid bed accumulator CSD, and the cold end outlet of the solid bed accumulator CSD is connected to the nitrogen channel inlet of the vaporization heat exchanger EVAEH. After the cold energy is released, the nitrogen returns to the atmospheric pressure nitrogen pipeline network. In the second path, the outlet of the nitrogen circulating fan NF is connected to the inlet of the nitrogen pre-cooling channel of the liquefied heat exchanger CONEH. The cooled nitrogen enters the solid bed accumulator CSD for cold storage, and then returns to the atmospheric pressure nitrogen pipeline network.

[0029] Specifically, the nitrogen circulation fan NF, as the core power unit for cooling energy circulation and distribution, has two nitrogen circulation paths that are physically parallel and can operate independently or collaboratively, in order to achieve efficient and controllable transfer of cooling energy between the solid bed accumulator CSD and the heat exchange system.

[0030] The first path constitutes a cold energy release loop: When the system is operating during off-peak electricity hours or requires external oxygen supply, the outlet of the nitrogen circulation fan NF is connected to the inlet on the cold energy storage medium side of the solid bed accumulator (CSD) via a first pipeline. The CSD is filled with solid cold energy storage materials with high specific heat capacity, such as alumina or metal fillers. At room temperature or near room temperature and at normal pressure, nitrogen gas enters the accumulator under the drive of the fan, flows through the complex porous channels of the cold energy storage material, and undergoes efficient indirect heat exchange with the stored low-temperature cold energy, significantly reducing the nitrogen temperature. The deeply cooled low-temperature nitrogen gas flows out from the outlet of the CSD and is transported through a second pipeline to the inlet of a specially designed nitrogen cooling channel in the vaporization heat exchanger (EVAEH). Inside the EVAEH, this low-temperature nitrogen gas acts as a cold source, indirectly exchanging heat with high-pressure liquid oxygen from the liquid oxygen pump OP, absorbing a large amount of latent heat required for liquid oxygen vaporization, causing the liquid oxygen to completely vaporize into gaseous oxygen that meets the requirements of the pipeline network. After completing the task of releasing cold energy, the nitrogen gas temperature rises and then returns to the atmospheric nitrogen gas network through the third pipeline, forming a complete cold energy utilization cycle.

[0031] The second path constitutes the cold energy storage loop: During peak power periods or when oxygen liquefaction energy storage is in operation, the outlet of the nitrogen circulating fan NF is switched via the fourth pipeline to the inlet of the nitrogen pre-cooling channel in the liquefaction heat exchanger CONEH. Atmospheric-pressure nitrogen from the pipeline network first enters the liquefaction heat exchanger CONEH, where it is pre-cooled by the lower-temperature process fluids in the system, such as nitrogen after expansion cooling or cryogenic liquid nitrogen, resulting in an initial temperature drop. This pre-cooled nitrogen flows out from the corresponding outlet of the liquefaction heat exchanger CONEH and enters a different flow channel on the other side or the same side of the solid-bed regenerator CSD via the fifth pipeline. As the nitrogen flows through the regenerator, it transfers its carrying cold energy to the solid-state cold storage material, lowering the material temperature and thus achieving long-term, low-loss storage of cold energy. The temperature of the released nitrogen further decreases or, according to design, approaches the inlet temperature, finally returning to the atmospheric-pressure nitrogen pipeline network via the sixth pipeline, completing the cold energy storage process.

[0032] The two paths are precisely controlled by a set of switching valves, such as three-way valves or combined shut-off valves, automatically adjusted by the control system. This design allows the system to flexibly choose whether to store cold energy in the solid-state bed energy storage, or to extract cold energy from the solid-state bed for auxiliary vaporization energy release, or even achieve a hybrid mode of partial storage and partial utilization, based on real-time operating conditions. This greatly improves the system's ability to cope with complex electricity price curves and downstream gas consumption fluctuations, as well as its overall energy efficiency. The solid-state bed cold storage unit (CSD) itself can adopt an alternating counter-current regeneration design, maintaining the uniformity of the axial temperature distribution of the cold storage material and the cold energy storage efficiency by periodically switching the airflow direction.

[0033] Example 3

[0034] Based on the above embodiment two, this example also includes: The data acquisition module is used to collect real-time data on oxygen production, liquid oxygen storage, downstream gas load, pipeline pressure, temperature, and time-of-use electricity price signals. Historical database is used to store oxygen supply and demand fluctuation data, system operation energy efficiency data, and operation strategy records corresponding to electricity price periods for at least one year; The predictive analytics module uses time series analysis and machine learning algorithms to predict oxygen demand trends, electricity price changes during the next 24 hours to a week based on historical and real-time data, and the optimal energy storage / release strategy for the system, and outputs control recommendations to the control unit.

[0035] Specifically, the data acquisition module consists of a network of multiple sensors distributed at key nodes of the system, which collect and upload two types of core data in real time: First, process parameters, including but not limited to the instantaneous and cumulative oxygen production of the main tower of the air separation unit, the liquid oxygen vacuum tank OT and liquid nitrogen vacuum tank NT levels and pressures, the instantaneous flow rate and cumulative consumption of each major downstream gas-consuming unit, the pressure and temperature of the high / low pressure oxygen pipeline and nitrogen pipeline, the material temperature and temperature difference at key points of the vaporization heat exchanger EVAEH and liquefaction heat exchanger CONEH, the current and speed of each pump OP and NP, the opening degree of each throttle valve OV and NV, the inlet and outlet pressure and temperature and power consumption of the nitrogen compressor NC, and the air pressure and air volume of the nitrogen circulating fan NF; Second, market and planning parameters, mainly referring to time-of-use electricity price signals received from the grid or built-in, including real-time electricity prices, peak-valley-flat electricity price time periods, and possible downstream user production plans or demand forecasts.

[0036] The historical database employs a hybrid architecture combining time-series and relational databases to persistently store all collected real-time data, forming a historical dataset. The stored data should cover at least a full annual operating cycle to capture seasonal and cyclical production fluctuations. The stored data types include not only raw sensor readings but also pre-processed and statistically calculated historical records of key performance indicators (KPIs), such as: daily / monthly oxygen venting rate, total liquid oxygen storage / release, system-wide energy consumption per standard cubic meter of oxygen processing, operating cost comparisons during peak and off-peak electricity periods, the charging / discharging efficiency curves of the solid-state cryogenic storage (CSD), and control strategies adopted and their effectiveness evaluation reports for addressing different supply-demand imbalances and electricity price patterns.

[0037] The predictive analysis module is the intelligent core of this subsystem, with its software algorithms integrated into a separate industrial server or the host computer of the control system. This module first cleans, normalizes, and extracts features from the historical database, identifying the correlation patterns between oxygen demand and factors such as production load, time hours, weekdays / weekends, seasons, and electricity prices. Based on this, the module employs a hybrid prediction model: for short-term oxygen demand forecasting of the next 24 to 72 hours, it primarily uses a Long Short-Term Memory (LSTM) model based on an attention mechanism, which effectively handles long-term dependencies and nonlinear characteristics of time series data; for medium-term trend forecasting of the next week to month, it combines a seasonal autoregressive integral moving average (SARIMA) model with planning information from downstream users for correction. Simultaneously, the module embeds an optimization decision-making model. This model uses the minimum total system operating cost (electricity cost) and equipment depreciation (equipment loss) or the highest overall energy efficiency as its objective function, constrained by equipment capacity, material balance, and safety. Combining the predicted oxygen demand curve and the known electricity price curve, it uses linear programming or dynamic programming algorithms to continuously solve for the optimal system operation strategy schedule for the next cycle, typically within 24 hours. This schedule details the start-up and shutdown times for each subsystem's liquefaction, vaporization, and energy storage; the setpoint change sequences for each regulating device's pumps, valves, compressors, and fans; and the expected operating modes of the solid-bed cryogenic storage unit (CSD): charging, holding, and releasing. The predictive analytics module pushes this optimal strategy schedule, along with key risk warnings such as predicted demand exceeding storage capacity, to the control unit in real time as control recommendations.

[0038] Furthermore, based on the control suggestions output by the predictive analysis module, the control unit dynamically adjusts the speed of the liquid oxygen pump OP and the liquid nitrogen pump NP, the opening degree of the liquid oxygen throttle valve OV and the liquid nitrogen throttle valve NV, the operating frequency of the nitrogen compressor NC, and the start / stop and operation of the nitrogen circulating fan NF.

[0039] Specifically, the control unit, as the central hub for instruction execution and closed-loop regulation of the entire system, receives optimal control suggestions from the predictive analysis module and transforms them into specific, executable sequences of equipment control instructions. At the core of the control unit is a programmable logic controller (PLC) or a distributed control system (DCS), which internally runs a control logic program developed according to the technological process and optimization objectives of this invention.

[0040] The control unit provides comprehensive, multi-variable, and coordinated dynamic regulation of the system. During peak electricity / oxygen surplus periods in liquefaction mode, the control unit gradually increases the speed of the liquid nitrogen pump NP according to a strategy to increase the circulating liquid nitrogen flow rate and cooling capacity. Simultaneously, it fine-tunes the opening of the liquid oxygen throttle valve OV to control the liquefaction pressure and temperature on the oxygen side of the liquefaction heat exchanger CONEH, ensuring liquefaction efficiency and safety. It simultaneously starts the nitrogen circulation fan NF and controls its connection to the cold storage circuit. By adjusting the fan frequency and path switching valve, it precisely controls the nitrogen flow rate and temperature entering the solid bed accumulator CSD, achieving an efficient "cold charging" process. During off-peak electricity / oxygen demand periods in vaporization mode, the control unit first instructs the liquid oxygen pump OP to increase its speed at a specific rate, extracting liquid oxygen from the vacuum tank and pressurizing it to the required pressure in the pipeline network. Simultaneously, it adjusts the liquid nitrogen throttle valve NV to ensure a suitable liquefaction rate on the nitrogen side of the vaporization heat exchanger EVAEH to provide a stable cold source. It starts the nitrogen compressor NC to the predetermined load and instructs the nitrogen circulation fan NF to switch to the cold release circuit. According to the real-time demand of vaporization load, it dynamically adjusts the fan air volume through the proportional-integral-derivative PID control algorithm, thereby accurately controlling the cold energy taken out from the solid bed, assisting the main cold source liquid nitrogen to complete the vaporization of liquid oxygen, and realizing the on-demand supply of the "cooling" process.

[0041] More importantly, the control unit possesses online adaptive adjustment capabilities. It continuously compares the actual operating parameters of the equipment under the preset strategy, such as the actual vaporization rate and actual energy consumption, with the expected values ​​given by the predictive analysis module. When deviations occur that may be due to prediction errors or equipment performance drift, the adaptive algorithm within the control unit will fine-tune the control parameters online, such as PID gain and valve response curves, or locally optimize the equipment setpoint within a certain safety boundary to ensure that the system always operates along the trajectory of optimal energy efficiency or lowest cost. For example, when it is found that the cooling rate of the solid bed regenerator (CSD) is lower than expected, the control unit may automatically increase the frequency of the nitrogen circulation fan (NF) or adjust the distribution of the material flow within the vaporization heat exchanger (EVAEH) to maintain the target vaporization load. This closed-loop control based on real-time feedback and model prediction is a key technical feature for achieving stable, economical, and efficient system operation.

[0042] Furthermore, during the operation of the aforementioned control unit: During peak power periods: the oxygen liquefaction system and solid bed energy storage system are started. The excess oxygen generated by the air separation unit is liquefied by the liquefaction heat exchanger CONEH and stored in the liquid oxygen vacuum tank OT. At the same time, the cold energy is stored in the solid bed cold accumulator CSD by the nitrogen circulation fan NF. During off-peak electricity hours: The nitrogen compression system and liquid oxygen vaporization system are started. The stored liquid oxygen is boosted by the liquid oxygen pump OP and sent to the vaporization heat exchanger EVAEH for vaporization, which then replenishes the low-pressure oxygen pipeline network. At the same time, the solid bed accumulator CSD releases cold energy to assist vaporization.

[0043] Specifically, the following coordinated operation method is executed by the control unit, which deeply couples electricity price signals, forecasted demand, and physical processes: Peak Power Hour Operation Phase: When the control system receives a signal indicating the start of the peak power hour, or when it predicts a peak in electricity prices and a trough in oxygen demand within the next few hours, it automatically triggers the energy storage operation mode. In this mode, the oxygen liquefaction system starts first: excess oxygen from the low-pressure pipeline of the air separation unit is introduced into the oxygen channel of the liquefaction heat exchanger CONEH. Simultaneously, the liquid nitrogen pump NP draws liquid nitrogen from the liquid nitrogen vacuum tank NT and pressurizes it, sending it into the nitrogen channel of the liquefaction heat exchanger CONEH as a refrigerant. The two undergo countercurrent heat exchange within the heat exchanger, cooling and ultimately liquefying the oxygen. The liquefied liquid oxygen is then moderately depressurized by the liquid oxygen throttling valve OV and flows stably into the liquid oxygen vacuum tank OT for long-term storage, achieving "time transfer" of oxygen. At the same time, the solid-bed energy storage system starts synchronously and operates in a "cooling" state: the nitrogen circulation fan NF starts, pressurizing the pipeline nitrogen and sending it into the pre-cooling channel of the liquefaction heat exchanger CONEH. This portion of nitrogen is initially cooled by the excess cooling energy generated during the liquefaction process, such as the cryogenic nitrogen from the nitrogen expander ET outlet, and then introduced into the solid-bed regenerator (CSD). As the cryogenic nitrogen flows through the regenerator, it transfers its cooling energy to the solid packing material, causing the packing temperature to decrease and the nitrogen itself to recover before being discharged. This process stores the excess cooling energy or waste cooling that cannot be directly utilized in the liquefaction system as sensible heat in the solid bed, improving the overall cooling energy utilization rate of the liquefaction process and providing a cheap cooling source for vaporization during off-peak electricity periods.

[0044] Off-peak electricity operation phase: When the control system receives a signal indicating the start of the off-peak electricity period, or predicts that downstream gas demand will peak, it automatically triggers the energy release gas supply operation mode. In this mode, the nitrogen compression system and liquid oxygen vaporization system are the main systems initially put into operation: the nitrogen compressor NC starts, compressing the pipeline nitrogen to a higher pressure and sending it into the nitrogen channel of the vaporization heat exchanger EVAEH. At the same time, the liquid oxygen pump OP draws stored liquid oxygen from the liquid oxygen vacuum tank OT and pressurizes it to the pressure required by the oxygen supply network, also sending it into the oxygen channel of the vaporization heat exchanger EVAEH. High-pressure liquid oxygen and high-pressure nitrogen exchange heat in the heat exchanger. The liquid oxygen absorbs heat and completely vaporizes, becoming qualified product oxygen that is delivered to the downstream pipeline network; the high-pressure nitrogen is partially or completely liquefied to provide cooling capacity. After liquefaction, the liquid nitrogen is throttled by the liquid nitrogen throttling valve NV, with the gas phase returning to the heat exchanger for reheating, and the liquid phase replenishing the liquid nitrogen vacuum tank NT. Simultaneously, the solid-bed energy storage system switches to "cooling" mode for auxiliary operation: the nitrogen circulation fan (NF) switches its path, sending ambient temperature nitrogen into the solid-bed cryogen (CSD) to extract the stored cold energy. After being converted into low-temperature nitrogen, it is directly introduced into the auxiliary cold source inlet of the vaporization heat exchanger (EVAEH). This portion of low-temperature nitrogen, acting as an additional cold source, can share part of the cooling load of the main nitrogen flow, thereby allowing for a reduction in the outlet pressure or flow rate of the nitrogen compressor (NC) under the same vaporization load, or achieving a higher liquid oxygenation capacity with the same nitrogen compression power consumption. This significantly reduces the overall operating power consumption during off-peak hours, maximizing the benefits of peak shaving and valley filling, and energy cost savings.

[0045] Furthermore, the above embodiments also include historical data comparison and analysis. After each cycle, the system automatically compares the differences in oxygen recovery rate, energy consumption, and gas supply stability between the current cycle and the same period in history. Combined with the output of the predictive analysis module, the system dynamically adjusts the oxygen remaining threshold for liquefaction start-up, the timing and flow rate of vaporization release, and the cooling capacity allocation ratio of the solid bed accumulator (CSD) in the next cycle.

[0046] Specifically, after each complete operating cycle, typically 24 hours, or a peak-valley cycle, the system does not immediately clear the data but automatically initiates a background analysis process. This process first performs a "historical comparison analysis": the system retrieves operating cycle data from the historical database for a past period, such as the previous week, month, or the same season last year, under similar date types, such as weekdays, weekends, and similar weather conditions. It then compares the actual operating data of the current cycle, such as the actual total oxygen recovery, the actual charging and discharging cooling efficiency of the solid-state bed, the system's time-of-day power consumption and electricity costs, the downstream gas supply pressure stability indicators with historical data for the same period, and the predicted values ​​made by the predictive analysis module before the start of the current cycle, across multiple dimensions. The comparison focuses not only on absolute values ​​but also on trends, deviation rates, and correlations.

[0047] Based on the results of the comparative analysis, the system will generate a "Performance Diagnosis and Optimization Recommendation Report". The report may point out, for example: "During the current type of spring workday, the model predicted a slower rate of decline in oxygen demand after the evening peak, resulting in a slightly later start-up of the liquefaction system and causing an oxygen venting loss of about 5%"; or "It was found that the charging efficiency of the solid bed accumulator decreased by about 3% after a week of continuous high-load operation, which may be related to slight blockage of the packing or uneven temperature distribution."

[0048] Next, the machine learning component in the predictive analytics module uses these newly generated comparison results as training data to incrementally learn or fine-tune its predictive model. For example, it adjusts certain weights in the LSTM model that affect short-term demand forecasting, or updates the correction coefficients in the decision-making model regarding equipment efficiency degradation. Simultaneously, the control unit adaptively adjusts certain control thresholds or logic based on the diagnostic report.

[0049] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions, characterized in that, include: Nitrogen compression system, which includes a nitrogen compressor (NC); The liquid oxygen vaporization system includes a vaporization heat exchanger (EVAEH), a liquid oxygen pump (OP), a liquid nitrogen throttle valve (NV), and a liquid nitrogen vacuum tank (NT). The oxygen liquefaction system includes a liquefaction heat exchanger (CONEH), a liquid nitrogen pump (NP), a nitrogen expander (ET), a liquid oxygen throttle valve (OV), and a liquid oxygen vacuum tank (OT). Solid-state bed energy storage system, which includes a solid-state bed accumulator (CSD) and a nitrogen circulation fan (NF). The nitrogen circulation refrigeration system includes a circulating nitrogen compressor (RNC), a nitrogen booster expander (ETC), and a nitrogen booster expander (ET). The control unit is used to control the various systems to operate alternately during peak and off-peak electricity periods based on peak and off-peak electricity price signals and historical oxygen supply and demand data.

2. The oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions according to claim 1, characterized in that, The nitrogen compressor (NC) is connected to the vaporization heat exchanger (EVAEH); The vaporization heat exchanger (EVAEH) is connected to a liquid nitrogen throttle valve (NV), which has one return path to the vaporization heat exchanger and another path connected to the liquid nitrogen vacuum tank (NT). The liquid nitrogen vacuum tank (NT) is connected to the liquid nitrogen pump (NP).

3. The oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions according to claim 2, characterized in that, The liquid nitrogen pump (NP) is connected to the liquefaction heat exchanger (CONEH); The liquefaction heat exchanger (CONEH) is connected to the nitrogen expander (ET), and the outlet of the expander flows back to the liquefaction heat exchanger; The liquefaction heat exchanger (CONEH) is connected to the liquid oxygen throttle valve (OV); The liquid oxygen throttle valve (OV) is connected to the liquid oxygen vacuum tank (OT); The liquid oxygen vacuum tank (OT) is connected to the liquid oxygen pump (OP); The liquid oxygen pump (OP) is connected to the vaporization heat exchanger (EVAEH).

4. The oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions according to claim 3, characterized in that, The liquefaction heat exchanger (CONEH) is connected to the circulating nitrogen compressor (RNC), the circulating nitrogen compressor (RNC) is connected to the nitrogen booster expander pressurization section (ETC), the nitrogen booster expander pressurization section (ETC) is connected to the liquefaction heat exchanger (CONEH), the liquefaction heat exchanger (CONEH) is connected to the nitrogen booster expander expansion section (ET), and the nitrogen booster expander expansion section (ET) is in turn connected to the liquefaction heat exchanger (CONEH).

5. The oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions according to claim 4, characterized in that, The nitrogen circulating fan (NF) has two independent circulation paths, which are switched and controlled by valves, wherein: In the first path, the outlet of the nitrogen circulating fan (NF) is connected to the cold end inlet of the solid bed accumulator (CSD), and the cold end outlet of the solid bed accumulator (CSD) is connected to the nitrogen channel inlet of the vaporization heat exchanger (EVAEH). After the nitrogen is released, it returns to the atmospheric pressure nitrogen pipeline. In the second path, the outlet of the nitrogen circulating fan (NF) is connected to the inlet of the nitrogen precooling channel of the liquefied heat exchanger (CONEH). The cooled nitrogen enters the solid bed accumulator (CSD) for cold storage and then returns to the atmospheric pressure nitrogen pipeline network.

6. The oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions according to claim 5, characterized in that, Also includes: The data acquisition module is used to collect real-time data on oxygen production, liquid oxygen storage, downstream gas load, pipeline pressure, temperature, and time-of-use electricity price signals. Historical database is used to store oxygen supply and demand fluctuation data, system operation energy efficiency data, and operation strategy records corresponding to electricity price periods for at least one year; The predictive analysis module uses time series analysis and machine learning algorithms to predict oxygen demand trends, electricity price changes during the next 24 hours to a week based on historical data and real-time collected data, and the optimal energy storage / release strategy for the system, and outputs control suggestions to the control unit.

7. The oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions according to claim 6, characterized in that, The control unit dynamically adjusts the speed of the liquid oxygen pump (OP) and liquid nitrogen pump (NP), the opening degree of the liquid oxygen throttle valve (OV) and liquid nitrogen throttle valve (NV), the operating frequency of the nitrogen compressor (NC), and the start-up, shutdown, and airflow of the nitrogen circulating fan (NF) based on the control suggestions output by the predictive analysis module.

8. The oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions according to claim 6, characterized in that, During the operation of the control unit: During peak power periods: The oxygen liquefaction system and solid bed energy storage system are started. The excess oxygen generated by the air separation unit is liquefied by the liquefaction heat exchanger (CONEH) and stored in the liquid oxygen vacuum tank (OT). At the same time, the cold energy is stored in the solid bed cold storage unit (CSD) through the nitrogen circulation fan (NF). During off-peak electricity hours: The nitrogen compression system and liquid oxygen vaporization system are started. The stored liquid oxygen is pressurized by the liquid oxygen pump (OP) and sent to the vaporization heat exchanger (EVAEH) for vaporization, which then replenishes the low-pressure oxygen pipeline network. At the same time, the solid bed accumulator (CSD) releases cold energy to assist vaporization.

9. The oxygen-nitrogen liquid conversion and energy storage system for an air separation unit under peak-valley electricity conditions according to claim 8, characterized in that, It also includes historical data comparison analysis. After each cycle, it automatically compares the differences between the current cycle and the historical same period in terms of oxygen recovery rate, energy consumption, and gas supply stability. Combined with the output of the predictive analysis module, it dynamically adjusts the oxygen remaining threshold for liquefaction start-up, the timing and flow rate of vaporization release, and the cooling capacity distribution ratio of the solid bed accumulator (CSD) in the next cycle.

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