Low-energy constant temperature water supply system for ultrapure water electrolysis hydrogen production

Abstract

The present application relates to the technical field of hydrogen production by electrolysis of water, and provides a low-energy-consumption constant-temperature water supply system for hydrogen production by electrolysis of ultra-pure water, which comprises a PEM electrolytic cell, an ultra-pure water supply unit, a circulating water supply loop, a local purification and bypass unit, a data acquisition module, a data analysis module, an energy consumption determination module and an energy consumption control module; the data analysis module determines heat load matching parameters according to current, voltage, circulating flow and inlet and outlet water temperature, and determines water quality representation state and flow representation state; the energy consumption determination module first determines whether the temperature rise is a real heat load; under a non-real heat load state, the energy consumption control module determines the energy consumption abnormality reason according to the water quality and flow state, and performs pump and cooling reduction, short-time flow correction, local purification or current density control to reduce the additional energy consumption of constant-temperature water supply.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology through water electrolysis, specifically to a low-energy-consumption constant-temperature water supply system for hydrogen production through ultrapure water electrolysis. Background Technology

[0002] PEM electrolysis hydrogen production systems typically use ultrapure water as a reactant. After entering the PEM electrolyzer, the ultrapure water participates in the electrolysis reaction and, along with unreacted water and oxygen, forms reflux water that enters the circulating water supply loop. In this process, ultrapure water not only serves as a reactant supply but also carries away heat from the fuel cell stack, maintains the stack inlet temperature, carries away circulating contaminants, and stabilizes the anode water supply.

[0003] Existing constant temperature water supply systems typically adjust the circulation pump, cooling water flow rate, or heat exchange unit directly based on the inlet or return water temperature. When the return water temperature rises, the system often maintains a constant temperature by increasing the circulation flow rate, increasing the cooling water flow rate, or enhancing the heat exchange intensity.

[0004] Chinese Patent Publication No. CN112899726B discloses a water electrolysis hydrogen production system and its control method. In this system, an electrolyzer, a gas-liquid separation unit, a heat exchanger, and a circulating pump are connected in series via an electrolyte pipeline. A heat exchanger bypass is connected in parallel with the heat exchanger, forming an electrolyte circulation loop. By adjusting the flow rate of electrolyte flowing into the heat exchanger and its bypass, the heat dissipation of the water electrolysis hydrogen production system adapts to changes in the input power of the electrolyzer; that is, the heat dissipation of the system can change with the varying input power of the electrolyzer. Compared to existing heat dissipation solutions, the water electrolysis hydrogen production system provided in this application adds the flow rate of electrolyte flowing into the heat exchanger and its bypass as an adjustment factor for heat dissipation regulation, thus enhancing the heat dissipation regulation capability of the system. Therefore, the existing technology has the following problems: The system failed to consider whether the return water temperature rise of the PEM electrolyzer was caused by the actual electrolysis heat load. Because the cause of the temperature rise was not distinguished, high pump speed, high cooling or high heat exchange methods were used to maintain a constant temperature, which led to an increase in the additional energy consumption of the constant temperature water supply system. Summary of the Invention

[0005] To address this issue, the present invention provides a low-energy constant-temperature water supply system for hydrogen production by ultrapure water electrolysis, which overcomes the problem in the prior art that does not consider whether the return water temperature rise of the PEM electrolyzer is caused by the actual electrolysis heat load, and that the constant temperature is maintained by using high pump speed, high cooling or high heat exchange methods without distinguishing the cause of the temperature rise, resulting in increased additional energy consumption of the constant-temperature water supply system.

[0006] To achieve the above objectives, the present invention provides a low-energy constant-temperature water supply system for hydrogen production by electrolysis of ultrapure water, comprising a PEM electrolyzer having an inlet end, a return end and an electrical connection end, an ultrapure water supply unit connected to the inlet end and used to provide ultrapure water, a circulating water supply loop connected to the inlet end and the return end respectively, the circulating water supply loop including a circulating pump, an oxygen-water separator, a heat exchange unit and a return water pipeline, and a local purification and bypass unit disposed in the circulating loop; The data acquisition module includes the following components: inlet water temperature, return water temperature, current, voltage, circulation flow rate, inlet conductivity, return water conductivity, inlet total organic carbon, and return water total organic carbon, as well as the pressure difference before and after the stack in the PEM electrolyzer. The data analysis module is used to determine the reference temperature rise based on the current, voltage and circulation flow rate, and to determine the heat load matching parameters in combination with the inlet water temperature and the return water temperature; to determine the water quality characterization state based on the inlet conductivity, return water conductivity, inlet total organic carbon and return water total organic carbon; and to determine the flow characterization state based on the circulation flow rate and the pressure difference before and after the stack. The energy consumption determination module is used to determine whether the heat load state is the true heat load state based on the heat load matching parameters. In response to the heat load state being a non-real heat load state, the energy consumption control module is triggered to determine whether to call the water quality characterization state and the flow characterization state to determine the cause of the energy consumption anomaly, and to select an energy consumption control method based on the cause of the energy consumption anomaly, including reducing pump speed or cooling water flow rate, short-term flow correction, local purification, and reducing current density.

[0007] As a preferred technical solution for a low-energy constant-temperature water supply system for hydrogen production by ultrapure water electrolysis, the data analysis module determines the actual temperature rise based on the difference between the inlet water temperature and the return water temperature, and determines the heat load matching parameters based on the ratio of the actual temperature rise to the reference temperature rise.

[0008] As a preferred technical solution for a low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production, the data analysis module calculates the conductivity difference and total organic carbon difference based on the inlet conductivity, return water conductivity, inlet total organic carbon, and return water total organic carbon, and determines the water quality characterization status based on the conductivity difference and the total organic carbon difference, including: Based on the determination that both the difference in conductivity and the difference in total organic carbon are not greater than the corresponding water quality threshold, the water quality characterization state is determined to be a normal water quality state. Based on the determination results that the difference in conductivity and / or the difference in total organic carbon are greater than the corresponding water quality threshold, the water quality characterization state is determined to be a water quality disturbance state.

[0009] As a preferred technical solution for a low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production, the data analysis module determines the flow fluctuation value and pressure difference fluctuation value based on the circulating flow rate and the pressure difference before and after the stack within a preset time window, respectively, to determine the flow characterization state based on the flow fluctuation value and the pressure difference fluctuation value, including: Based on the determination that both the flow fluctuation value and the differential pressure fluctuation value are not greater than the corresponding flow threshold, the flow characterization state is determined to be a normal flow state. Based on the determination that the flow fluctuation value and / or the differential pressure fluctuation value are greater than the corresponding flow threshold, the flow characterization state is determined to be an abnormal flow state.

[0010] As a preferred technical solution for a low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production, the energy consumption determination module determines the heat load status based on heat load matching parameters, including: In response to the heat load matching parameters being within a preset load range, the heat load state is determined to be the actual heat load state. In response to the fact that the heat load matching parameters are not within the preset load range, the heat load state is determined to be an unreal heat load state.

[0011] As a preferred technical solution for a low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production, in response to the stated heat load state being a non-true heat load state, the energy consumption control module is triggered to determine the cause of the energy consumption anomaly, wherein: If the heat load matching parameter is lower than the lower limit of the preset load range, the cause of the abnormal energy consumption is determined to be energy redundancy. If the heat load matching parameter is higher than the upper limit of the preset load range, the cause of the abnormal energy consumption is determined by combining the water quality characterization status and the flow characterization status.

[0012] As a preferred technical solution for a low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production, an energy consumption control method is selected based on the causes of the energy consumption anomalies, including: In response to energy redundancy, the energy control module reduces the pump speed or the cooling water flow rate.

[0013] As a preferred technical solution for a low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production, the energy consumption control module determines the cause of energy consumption anomalies based on the water quality characterization status and the flow characterization status, and selects an energy consumption control method based on the cause of the energy consumption anomalies, including: In response to the cause of the energy consumption anomaly being that the flow characterization state is in an abnormal flow state, the energy consumption control method is determined to be short-term flow correction.

[0014] As a preferred technical solution for a low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production, the energy consumption control module determines the cause of energy consumption anomalies based on the water quality characterization status and the flow characterization status, and selects an energy consumption control method based on the cause of the energy consumption anomalies, further including: In response to the cause of the energy consumption anomaly being that the water quality characterization state is in a state of water quality disturbance, the energy consumption control method is determined to be to start local purification.

[0015] As a preferred technical solution for a low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production, the energy consumption control module determines the cause of energy consumption anomalies based on the water quality characterization status and the flow characterization status, and selects an energy consumption control method based on the cause of the energy consumption anomalies, further including: In response to the flow characterization state being normal and the water quality characterization state being normal, the cause of the abnormal energy consumption was determined to be a non-fluid-type temperature rise, and the energy consumption control method was determined to be reducing the current density.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: the low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production provided by the present invention first determines whether the temperature rise of the return water of the PEM electrolyzer matches the current electrolysis load by using heat load matching parameters, avoiding directly increasing the output of the circulating pump, the flow rate of cooling water, or the heat exchange intensity based solely on the actual temperature rise; when the heat load matching parameters are lower than the preset range, it is identified as energy consumption redundancy and the pump speed and / or cooling water flow rate are reduced; when the heat load matching parameters are higher than the preset range, the cause of abnormal energy consumption is determined by combining the water quality characterization status and the flow characterization status, and short-term flow correction, local purification, or reduction of current density are performed accordingly; thereby avoiding misjudging non-real heat load temperature rise as real heat load that needs to be maintained with long-term high energy consumption, and improving the energy consumption control accuracy and operational stability of the constant-temperature water supply system.

[0017] In particular, this invention uses the actual temperature rise and the reference temperature rise to determine the heat load matching parameters, so that the return water temperature rise judgment no longer depends on a single temperature value, but is compared with the reasonable temperature rise corresponding to the current current, voltage and circulation flow rate; it can distinguish between the real heat load, energy consumption redundancy and abnormal temperature rise, and provide a clear preliminary judgment basis for subsequent energy consumption control. In particular, this invention only triggers calculation and calls water quality characterization status and flow characterization status when the heat load matching parameter is higher than the preset range to divert the abnormal cause, avoiding the problem of invalid computing power wastage and continuous energy waste caused by the full-time parallel operation of the data analysis module, and realizing on-demand scheduling of detection and computing resources; under the actual heat load state, the analysis of water quality characterization status and flow characterization status can be stopped and only the heat load matching parameter needs to be determined, so it can be in a low power consumption state, which reduces the occupation of system computing power and also reduces the wear and tear and maintenance costs of hardware modules; In particular, the present invention selects different control methods according to different causes of abnormal energy consumption: for energy consumption redundancy, the pump speed and / or cooling water flow rate are reduced; for flow abnormalities, short-term flow correction is performed; for water quality disturbances, local purification is initiated; for abnormal temperature rises where both flow and water quality are normal, the current density is reduced; thus avoiding long-term high pump speed, high cooling or high heat exchange operation and reducing the additional energy consumption of the water supply system. Attached Figure Description

[0018] Figure 1 A flowchart illustrating the process of determining the cause of abnormal energy consumption in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0020] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0021] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0022] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] It is understood that in the low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production provided in this embodiment of the invention, ultrapure water, as a reactant in PEM electrolysis hydrogen production, enters the electrolyzer through the anode side of the PEM electrolyzer. During the electrolysis process, it participates in the water decomposition reaction and returns to the circulating water supply loop along with oxygen and unreacted water to form reflux water. The reflux water simultaneously serves to replenish reactants, remove heat from the reactor, separate oxygen and water, and carry away pollutants during the circulation process. Therefore, the constant-temperature water supply system for the PEM electrolyzer is not only used to replenish reaction water, but is directly related to the thermal management, water quality maintenance, stable circulation flow, and energy consumption control of the electrolyzer.

[0024] In practical engineering, the constant temperature water supply system of PEM electrolyzers needs to increase the output of circulating pumps, cooling water flow rate, or heat exchange intensity to maintain the inlet temperature. However, this temperature rise is not necessarily caused by the actual electrolysis heat load. If all return water temperature rises are regarded as the actual heat load, it may lead to long-term high-frequency operation of circulating pumps, continuous increase in cooling water, overwork of heat exchange units, or unnecessary operation of local purification units, thereby increasing the additional energy consumption of the water supply system. To this end, this invention first determines whether the current temperature rise belongs to the actual heat load by using heat load matching parameters. Then, under non-actual heat load conditions, it determines the cause of abnormal energy consumption by combining water quality characterization and flow characterization conditions, thereby selecting control methods such as reducing pump speed, reducing cooling water flow rate, short-term flow correction, local purification, or reducing current density.

[0025] Please see Figure 1 The diagram shown illustrates the workflow for determining the cause of abnormal energy consumption in an embodiment of the present invention. This embodiment provides a low-energy-consumption constant-temperature water supply system for hydrogen production via ultrapure water electrolysis, comprising a PEM electrolyzer, an ultrapure water supply unit, a circulating water supply loop, a local purification and bypass unit, a data acquisition module, a data analysis module, an energy consumption determination module, and an energy consumption control module.

[0026] Specifically, the PEM electrolyzer has an inlet end, a return end, and an electrical connection end. The inlet end is used to receive ultrapure water from the ultrapure water supply unit or the circulating water supply circuit; the return end is used to discharge the gas-liquid mixture reflux water containing oxygen and unreacted water; and the electrical connection end is used to connect to the electrolysis power supply so that the PEM electrolyzer can carry out water electrolysis reaction under the action of current.

[0027] Specifically, the ultrapure water supply unit is connected to the inlet of the PEM electrolyzer and is used to supply ultrapure water that meets the operating requirements of the PEM electrolyzer. The ultrapure water supply unit includes one or more of the following: raw water pretreatment unit, reverse osmosis unit, electrodeionization unit, polishing unit, ultrapure water storage tank and water replenishment valve group, to ensure that the water quality entering the PEM electrolyzer meets the operating requirements of the electrolyzer.

[0028] Specifically, the circulating water supply circuit is connected to the inlet and outlet of the PEM electrolyzer, respectively, to allow ultrapure water to circulate between the PEM electrolyzer and the outlet water pipeline. The circulating water supply circuit includes a circulating pump, an oxygen-water separator, a heat exchange unit, and an outlet water pipeline. The circulating pump drives the ultrapure water to circulate through the PEM electrolyzer. The oxygen-water separator separates the gas-liquid mixture discharged from the outlet water of the PEM electrolyzer. The heat exchange unit regulates the temperature of the return water or the ultrapure water entering the PEM electrolyzer. The outlet water pipeline returns the return water after gas-liquid separation and temperature regulation to the inlet side of the PEM electrolyzer.

[0029] Specifically, the local purification and bypass unit is set in the circulating water supply loop to locally purify at least a portion of the return water, or to allow at least a portion of the return water to bypass the local purification structure and return to the PEM electrolyzer. The local purification and bypass unit may include one or more of the following: ion exchange polishing column, local purification branch, bypass valve, switching valve, and discharge branch, to purify only a portion of the return water when the water quality is disturbed, thus avoiding high-energy-consuming and high-flow-rate purification of the entire circulation loop.

[0030] Specifically, the data acquisition module is used to acquire the operating data of the PEM electrolyzer and the circulating water supply loop, including the operating data of the PEM electrolyzer (current, voltage), the data of the inlet and outlet water boundaries of the electrolyzer (inlet water temperature, return water temperature, pressure difference before and after the stack), and the operating data of the circulating water supply loop (circulation flow rate, inlet conductivity, return water conductivity, inlet total organic carbon, return water total organic carbon). Among them: the current and voltage of the PEM electrolyzer represent the current electrolysis load, the inlet and return water temperatures of the electrolyzer represent the actual temperature rise, the pressure difference before and after the stack of the electrolyzer reflects the change in flow resistance when ultrapure water passes through the PEM electrolyzer, the circulation flow rate represents the water supply capacity and flow stability, and the inlet conductivity, return water conductivity, inlet total organic carbon and return water total organic carbon can represent whether the water quality is disturbed during the circulation process; In implementation, (1) a DC current sensor or Hall current sensor is installed at the electrical connection end of the PEM electrolyzer (the positive or negative busbar between the electrolysis power supply and the electrolyzer) to detect the working current output from the electrolysis power supply to the electrolyzer; a voltage acquisition device (isolated voltage transmitter) is connected in parallel at both ends of the PEM electrolyzer (between the anode and cathode of the electrolyzer) to detect the working voltage of the individual electrolyzer or the entire stack; (2) a temperature sensor (usually a PT100 platinum resistance temperature sensor) is installed on the inlet pipe, the outlet pipe, or the outlet pipe of the oxygen-water separator of the PEM electrolyzer to detect the incoming current. The ultrapure water inlet temperature and return water temperature of the electrolysis cell are measured by setting pressure sensors at the inlet and return water ends of the PEM electrolysis cell to detect the pressure difference between the two ends of the electrolysis cell (usually a differential pressure transmitter or a high-precision pressure sensor); (3) An electromagnetic flow meter or mass flow meter is set in the circulating water supply loop to detect the circulating water flow rate. Online conductivity sensors are set before the circulating loop enters the electrolysis cell and in the return water pipeline (or at the outlet of the oxygen-water separator) to detect the inlet conductivity and return water conductivity of the electrolysis cell. Online TOC analyzers are set at the inlet and return water ends of the circulating water supply loop to obtain the total organic carbon inlet and the total organic carbon in the return water. In actual engineering, temperature sensors are placed on the straight sections of the inlet and return water pipes respectively; differential pressure sensors are placed at both ends of the electrolytic cell inlet and outlet; flow meters are placed at the outlet of the circulating pump or in the main circulation pipe; and conductivity and TOC detectors are placed at key nodes on the inlet and return water sides of the circulating water supply circuit.

[0031] Specifically, the data analysis module determines the actual temperature rise based on the difference between the inlet water temperature and the return water temperature, i.e., actual temperature rise = return water temperature - inlet water temperature; Specifically, the data analysis module determines the reference temperature rise under the current operating conditions based on the current, voltage, and circulation flow rate, and determines the heat load matching parameters based on the ratio of the actual temperature rise to the reference temperature rise. During implementation, during the equipment commissioning phase, the PEM electrolyzer is controlled to operate under the conditions of normal water quality, normal flow, and no abnormal alarms, and multiple sets of data (including current, voltage, circulation flow, inlet temperature, and return water temperature) are collected. Then, the experimental temperature rise corresponding to each set of data is obtained. The experimental temperature rise during stable operation is plotted as a curve and used as a reference temperature rise curve. The corresponding reference temperature rise is determined based on the current, voltage, and circulation flow during implementation on the reference temperature rise curve. It is understandable that if no prior experiments are conducted, the reference temperature rise can be determined based on the heat balance calculation method, but due to individual differences between equipment, the calculated reference temperature rise may not be accurate enough. It should be understood that the reference temperature rise represents the reasonable temperature rise level under the current operating conditions. The ratio of the actual temperature rise to the reference temperature rise can eliminate the influence of different electrolysis loads and different circulation flow rates on the absolute value of the temperature rise, making the return water temperature rise under different operating conditions comparable. The heat load matching parameter represents the degree of matching between the actual temperature rise and the reasonable temperature rise corresponding to the current electrolysis load.

[0032] Specifically, the energy consumption determination module determines the heat load status based on the heat load matching parameters, including: In response to the heat load matching parameters being within the preset load range, the heat load state is determined to be the actual heat load state. It can be understood that the heat load matching parameters being within the preset matching range indicates that the actual temperature rise is basically consistent with the reference temperature rise, and the current temperature rise can be determined to be the actual heat load temperature rise. Therefore, the current heat exchange, cooling and circulation process can be maintained. In response to the heat load matching parameters not being within the preset load range, the heat load state is determined to be an unreal heat load state, and the energy consumption control module is triggered to determine the cause of the energy consumption anomaly, wherein: If the heat load matching parameter is lower than the lower limit of the preset load range, the cause of the abnormal energy consumption is determined to be energy consumption redundancy. It can be understood that if the heat load matching parameter is less than the preset minimum threshold, it means that the actual temperature rise is lower than the reasonable temperature rise under the current operating conditions. The constant temperature water supply system may have energy consumption redundancy caused by overcooling or overcirculation. At this time, energy consumption redundancy can be eliminated simply by reducing the pump speed or reducing the cooling water flow rate. If the heat load matching parameter is higher than the upper limit of the preset load range, it means that the actual temperature rise exceeds the range that the current electrolysis load can explain. The current temperature rise should not be directly identified as the actual heat load temperature rise. It is necessary to further combine the water quality characterization status and the flow characterization status to determine the cause of the energy consumption anomaly. Therefore, the data analysis module is triggered to determine the water quality characterization status and the flow characterization status. It is understandable that a heat load matching parameter close to 1 indicates that the actual temperature rise is basically consistent with the reasonable temperature rise corresponding to the current electrolysis load and circulation flow rate. The current temperature rise can be considered to be caused by the actual electrolysis heat load. In implementation, the preset load range is 0.85 to 1.15, which avoids misjudgment caused by sensor noise or short-term thermal inertia, and promptly identifies energy consumption redundancy or abnormal temperature rise when the actual temperature rise deviates significantly from the reasonable temperature rise.

[0033] Specifically, the data analysis module calculates the conductivity difference and total organic carbon difference based on the inlet conductivity, return water conductivity, inlet total organic carbon, and return water total organic carbon, and determines the water quality characterization status based on these differences. It should be understood that the inlet conductivity represents the ionic contamination level before entering the PEM electrolyzer, the return water conductivity represents the ionic contamination level formed after the water passes through the stack, oxygen-water separator, heat exchanger, pump, and pipeline, the inlet TOC represents the organic contamination level before entering the stack, and the return water TOC represents the organic contamination level that may be introduced during the circulation process by seals, resin, pipelines, pumps, heat exchangers, etc. Therefore, the conductivity difference can characterize whether ionic contamination disturbances occur during the circulation process, and the total organic carbon difference can characterize whether organic contamination disturbances occur during the circulation process. During implementation, the conductivity difference and total organic carbon difference were both below the corresponding water quality thresholds, indicating that after the water passed through the PEM electrolysis cell and the circulating water supply loop, the changes in conductivity and TOC were within the allowable disturbance range, and no significant new ion pollution or organic pollution was observed. Therefore, the water quality was determined to be in a normal state. However, if the conductivity difference and / or total organic carbon difference were above the corresponding water quality thresholds, it indicated that at least one type of significant disturbance occurred during the water circulation process. This included conductivity differences exceeding the limit, which tended to be ion pollution, metal ion precipitation, resin failure, or inorganic pollution, or TOC differences exceeding the limit, which tended to be organic leaching, sealant precipitation, organic resin release, or pipeline material pollution. Therefore, the water quality was determined to be in a disturbed state. In implementation, water quality thresholds include conductivity difference thresholds and total organic carbon difference thresholds. The conductivity difference threshold ranges from 0.05 μS / cm to 0.15 μS / cm, and the total organic carbon difference threshold ranges from 10 μg / L to 20 μg / L (approximately 10 ppb to 20 ppb). It is understood that water quality thresholds can be adjusted based on the influent water quality requirements of the PEM electrolyzer, the stable influent water quality value, sensor detection accuracy, and the water quality fluctuation range under stable operating conditions. Typically, the water quality threshold should be less than the difference between the corresponding absolute water quality limit and the stable influent water quality value, and should be greater than a preset multiple of the water quality difference fluctuation under stable operating conditions. This is to avoid misjudgments due to detection noise and to prevent the identification of early water quality disturbances during the circulation process before the return water quality approaches the absolute limit.

[0034] Specifically, the data analysis module determines the flow fluctuation value and the pressure difference fluctuation value based on the circulating flow rate and the pressure difference before and after the stack within a preset time window, respectively, so as to determine the flow characterization state based on the flow fluctuation value and the pressure difference fluctuation value. It can be understood that significant fluctuations in the circulating flow rate or the pressure difference before and after the stack in a short period of time usually indicate that there are flow disturbances such as unstable flow rate, changes in gas-liquid entrainment, changes in local flow channel resistance, or uneven release of bubbles in the circulating water supply loop. In implementation, the flow fluctuation value is the ratio of the difference between the maximum and minimum circulating flow rate within a preset time window to the average circulating flow rate within that time window; the pressure difference fluctuation value is the ratio of the difference between the maximum and minimum pressure difference before and after the stack within a preset time window to the average pressure difference before and after the stack within that time window; the preset time window (the time window between the preset time before the current time and the current time) should be greater than the normal pulsation cycle of the circulating pump and the transient time corresponding to the sensor sampling noise to avoid misjudgment caused by single-point sampling fluctuations, and less than the thermal inertia response time of the PEM electrolyzer so as to identify flow anomalies before the abnormal temperature rise is masked by continuous high-energy cooling or high-flow circulation. The duration of the preset time window is usually 30s to 60s; If the flow rate fluctuation value and the differential pressure fluctuation value are both not greater than the corresponding flow threshold, it indicates that the water supply capacity of the circulating water supply loop and the flow resistance in the PEM electrolyzer are both within the allowable fluctuation range, so the flow characterization state is determined to be a normal flow state; if the flow rate fluctuation value and / or differential pressure fluctuation value are greater than the corresponding flow threshold, it indicates that at least one of the circulating flow stability or the flow resistance in the pile has abnormal fluctuation, so the flow characterization state is determined to be an abnormal flow state. During implementation, multiple sets of circulating flow rate and pressure difference data before and after the stack are collected under stable operating conditions with normal water quality, matching heat load, and no abnormal flow alarms. The stable flow rate fluctuation benchmark value and the stable pressure difference fluctuation benchmark value are determined, and the corresponding flow threshold is set to 2 to 4 times the stable fluctuation benchmark value. This is to avoid misjudgment caused by inherent pulsation of the circulating pump, valve fine adjustment, or sensor noise, and to promptly identify abnormal flow conditions when gas-liquid disturbance, abnormal local flow resistance, or unstable water supply leads to an increase in heat load matching parameters. The flow threshold includes the flow rate fluctuation threshold and the pressure difference fluctuation threshold, and the flow threshold is usually less than 0.15.

[0035] Understandably, the water quality characterization status is used to characterize whether ionic or organic water quality disturbances occur after ultrapure water passes through the PEM electrolyzer and the circulating water supply loop; the flow characterization status is used to characterize whether the water flow in the circulating water supply loop and the PEM electrolyzer is stable.

[0036] Specifically, the energy consumption determination module combines the water quality characterization status and the flow characterization status to determine the cause of energy consumption anomalies, and selects an energy consumption control method based on the cause of the energy consumption anomalies, including: The response that the abnormal energy consumption was due to an abnormal flow characterization state indicates that the actual temperature rise may be caused by unstable water supply flow, abnormal flow resistance within the reactor, or gas-liquid disturbance. In this case, the cause of the abnormal energy consumption is determined to be a flow-abnormal temperature rise. The main reason for the flow-abnormal temperature rise is that the ultrapure water cannot stably remove the heat from the reactor stack, rather than the water quality itself deteriorating. Therefore, the energy consumption control method is determined to be short-term flow correction. In implementation, short-term flow correction includes temporarily increasing the output of the circulating pump, pulse-type adjustment of the circulating flow rate, adjustment of the bypass valve opening, or performing short-term flushing to restore the flow stability state, and reducing the output of the circulating pump after the flow characterization state returns to normal to avoid increased energy consumption caused by long-term high pump speed operation. The abnormal energy consumption was attributed to a water quality disturbance, indicating that the higher-than-expected temperature rise was likely related to changes in the circulating water quality. This disturbance could alter the internal resistance, local reaction environment, or heat transfer conditions of the electrolyzer. Simply increasing the cooling water flow rate or the circulating pump output to maintain a constant temperature would not eliminate the source of the disturbance. Therefore, the abnormal energy consumption was determined to be a water quality disturbance-related temperature rise, and the energy control method was identified as local purification. Local purification includes directing at least a portion of the return water into the local purification and bypass unit, or switching it to a purification branch, polishing branch, or discharge branch to reduce ion or organic disturbances in the return water. Once the water quality returned to normal, the local purification branch should be reduced or discontinued to lower the additional energy consumption of the purification unit. If the flow characterization status is normal and the water quality characterization status is normal, it indicates that the current abnormal temperature rise cannot be explained by abnormal water supply flow or water quality disturbance. In this case, the cause of abnormal energy consumption is determined to be a non-fluid-type temperature rise. The abnormal temperature rise is more likely due to changes in the electrochemical state, ohmic loss state, or heat source inside the PEM electrolyzer, rather than abnormal flow or water quality in the circulating water supply circuit. For this type of abnormality, it is difficult to reduce the temperature rise from the source by further increasing the output of the circulating pump, the cooling water flow rate, or the local purification intensity. Therefore, the energy consumption control method is determined to be to reduce the current density to directly reduce the electrolytic load and internal heating intensity of the PEM electrolyzer.

[0037] This invention can first determine whether the temperature rise in the return water of the PEM electrolyzer is a reasonable temperature rise caused by the actual electrolysis heat load when the temperature rise is reached. Then, it can perform limited diversion control on the temperature rise that is not due to the actual heat load, so as to avoid the constant temperature water supply system from continuously using high circulation, high cooling or high heat exchange to maintain the temperature in the case of abnormal temperature rise, thereby reducing the additional energy consumption of the constant temperature water supply system.

[0038] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-energy constant-temperature water supply system for hydrogen production by electrolysis of ultrapure water, comprising a PEM electrolyzer having an inlet end, a return end and an electrical connection end, an ultrapure water supply unit connected to the inlet end and used to provide ultrapure water, a circulating water supply loop connected to the inlet end and the return end respectively, wherein the circulating water supply loop includes a circulating pump, an oxygen-water separator, a heat exchange unit and a return water pipeline, and a local purification and bypass unit disposed in the circulating loop; Its features are, Also includes: The data acquisition module includes the following components: inlet water temperature, return water temperature, current, voltage, circulation flow rate, inlet conductivity, return water conductivity, inlet total organic carbon, and return water total organic carbon, as well as the pressure difference before and after the stack in the PEM electrolyzer. The data analysis module is used to determine the reference temperature rise based on the current, voltage and circulation flow rate, and to determine the heat load matching parameters in combination with the inlet water temperature and the return water temperature; to determine the water quality characterization state based on the inlet conductivity, return water conductivity, inlet total organic carbon and return water total organic carbon; and to determine the flow characterization state based on the circulation flow rate and the pressure difference before and after the stack. The data analysis module determines the actual temperature rise based on the difference between the inlet water temperature and the return water temperature, and determines the heat load matching parameters based on the ratio of the actual temperature rise to the reference temperature rise. The energy consumption determination module is used to determine whether the heat load state is the true heat load state based on the heat load matching parameters. In response to the heat load state being a non-real heat load state, the energy consumption control module is triggered to determine whether to call the water quality characterization state and the flow characterization state to determine the cause of the energy consumption anomaly, and to select an energy consumption control method based on the cause of the energy consumption anomaly, including reducing pump speed or cooling water flow rate, short-term flow correction, local purification, and reducing current density.

2. The low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production according to claim 1, characterized in that, The data analysis module calculates the conductivity difference and total organic carbon difference based on the inlet conductivity, return water conductivity, inlet total organic carbon, and return water total organic carbon, and determines the water quality characterization status based on the conductivity difference and total organic carbon difference, including: Based on the determination that both the difference in conductivity and the difference in total organic carbon are not greater than the corresponding water quality threshold, the water quality characterization state is determined to be a normal water quality state. Based on the determination results that the difference in conductivity and / or the difference in total organic carbon are greater than the corresponding water quality threshold, the water quality characterization state is determined to be a water quality disturbance state.

3. The low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production according to claim 1, characterized in that, The data analysis module determines the flow rate fluctuation value and the pressure difference fluctuation value based on the circulating flow rate and the pressure difference before and after the stack within a preset time window, respectively, to determine the flow characterization state based on the flow rate fluctuation value and the pressure difference fluctuation value, including: Based on the determination that both the flow fluctuation value and the differential pressure fluctuation value are not greater than the corresponding flow threshold, the flow characterization state is determined to be a normal flow state. Based on the determination that the flow fluctuation value and / or the differential pressure fluctuation value are greater than the corresponding flow threshold, the flow characterization state is determined to be an abnormal flow state.

4. The low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production according to claim 1, characterized in that, The energy consumption determination module determines the heat load status based on heat load matching parameters, including: In response to the heat load matching parameters being within a preset load range, the heat load state is determined to be the actual heat load state. In response to the fact that the heat load matching parameters are not within the preset load range, the heat load state is determined to be an unreal heat load state.

5. The low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production according to claim 4, characterized in that, In response to the heat load state being an unreal heat load state, the energy consumption control module is triggered to determine the cause of the energy consumption anomaly, wherein: If the heat load matching parameter is lower than the lower limit of the preset load range, the cause of the abnormal energy consumption is determined to be energy redundancy. If the heat load matching parameter is higher than the upper limit of the preset load range, the cause of the abnormal energy consumption is determined by combining the water quality characterization status and the flow characterization status.

6. The low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production according to claim 5, characterized in that, Based on the causes of the energy consumption anomalies, energy consumption control methods are selected, including: In response to energy redundancy, the energy control module reduces the pump speed or the cooling water flow rate.

7. The low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production according to claim 5, characterized in that, The energy consumption control module determines the cause of energy consumption anomalies based on the water quality characterization status and the flow characterization status, and selects an energy consumption control method based on the cause of the energy consumption anomalies, including: In response to the cause of the energy consumption anomaly being that the flow characterization state is in an abnormal flow state, the energy consumption control method is determined to be short-term flow correction.

8. The low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production according to claim 7, characterized in that, The energy consumption control module determines the cause of energy consumption anomalies based on the water quality characterization status and the flow characterization status, and selects an energy consumption control method based on the cause of the energy consumption anomalies, and further includes: In response to the cause of the energy consumption anomaly being that the water quality characterization state is in a state of water quality disturbance, the energy consumption control method is determined to be to start local purification.

9. The low-energy-consumption constant-temperature water supply system for ultrapure water electrolysis hydrogen production according to claim 7, characterized in that, The energy consumption control module determines the cause of energy consumption anomalies based on the water quality characterization status and the flow characterization status, and selects an energy consumption control method based on the cause of the energy consumption anomalies, and further includes: In response to the flow characterization state being normal and the water quality characterization state being normal, the cause of the abnormal energy consumption was determined to be a non-fluid-type temperature rise, and the energy consumption control method was determined to be reducing the current density.

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