System and method for purifying and recycling water electrolysis hydrogen production wastewater based on low-temperature distillation desalination

Abstract

The invention discloses a system and a method for purifying and recycling water electrolysis hydrogen production wastewater based on low-temperature distillation desalination, and belongs to the technical field of water electrolysis hydrogen production. The system comprises a raw water tank, a pure water system, a cooling system, a hydrogen production system, a wastewater tank, a low-temperature distillation system, a product water tank, a water quality detection system, an information collecting, processing and alarming system and a control system. According to the water electrolysis hydrogen production wastewater purification and recycling system and method based on low-temperature distillation desalination, the technical advantages that the low-temperature distillation desalination technology is low in inlet water quality requirement, low-grade waste heat can be coupled and the like are brought into full play, and resource recycling of wastewater is achieved through one recycling system. Through the cooperation of the water quality detection system, the information collection processing and alarm system and the control system, the safe and stable operation of the low-temperature distillation system is ensured, and the water quality of the raw water of the electrolyzed water hydrogen production system reaches the standard.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production by water electrolysis, and particularly relates to a system and method for purifying and recycling wastewater from hydrogen production by water electrolysis based on low-temperature distillation desalination. BACKGROUND

[0002] As a key link in the energy transformation under the "double carbon" goal, the market size and application range of hydrogen energy are increasing year by year. As the most urgent demand for electricity in the hydrogen energy industry chain, the most closely coupled with new energy, and the most relevant link of low-carbon clean energy, the present situation of hydrogen production by water electrolysis has attracted widespread attention. The daily operation of a large-scale water electrolysis hydrogen production system inevitably consumes a large amount of water resources as raw materials. In the process of producing high-purity water for hydrogen production through a pure water device, wastewater with high salt content is also produced as a byproduct. The cooling system of the water electrolysis hydrogen production system also discharges a large amount of production wastewater daily during daily operation. Most existing hydrogen production systems directly discharge or outsource the treatment of wastewater. Such a wastewater treatment mode not only adds environmental pressure to the local project and causes serious waste of water resources, but also increases the daily operating cost. After desalination, hydrogen production wastewater has considerable recycling potential. If not fully developed, this part of the blank needs to be filled with raw material water, which increases the operating cost of the hydrogen production system to some extent.

[0003] Among the few technical solutions currently proposed to solve this pain point, for example, patent announcement No. CN212247228U discloses a salt-containing wastewater recycling device based on electrolytic hydrogen production technology, which includes an electrolytic tank, a hydrogen aftertreatment device, and an externally connected COD detection device. The electrolytic tank has a COD electrode group, a hydrogen production electrode group, and a diaphragm separating the anode chamber and the cathode chamber. The electrolytic tank is provided with a salt-containing wastewater inlet and an electrolyte outlet. The hydrogen aftertreatment device is connected to the cathode chamber of the electrolytic tank. However, this method has the following disadvantages: This scheme electrolyzes salt-containing wastewater into chlorine and hydrogen while producing by-product sodium hypochlorite. In addition, this method only focuses on COD standards and chlorine ion removal, and cannot achieve purification of other water quality indicators. Moreover, it is only applicable to salt-containing wastewater, while the remaining electrolytic hydrogen production wastewater does not meet the recycling standards. For example, patent announcement No. CN222724180U discloses a wastewater treatment device for electrolytic water hydrogen production. The device includes a reagent configuration unit, a detection unit, a reaction unit, and a control unit. The reagent configuration unit includes a first configuration unit and a second configuration unit. The detection unit includes a first detection element and a second detection element. The first detection element is used to detect the water quality of the inlet water area, and the second detection element is used to detect the water quality of the outlet water area. The first configuration unit, the second configuration unit, the first detection element, and the second detection element are electrically connected to the control unit. This scheme only involves a wastewater treatment device for electrolytic water hydrogen production, but does not involve a recycling system for purifying wastewater, making it difficult to recycle wastewater. For example, patent publication No. CN118289965A discloses a wastewater zero-emission device for a large-scale electrolytic water hydrogen production system. The device uses multi-stage reverse osmosis membrane filtration and evaporation to achieve hydrogen production wastewater desalination. However, this scheme is relatively complex in technology, and the device is complex and large, which is not suitable for small and medium-sized hydrogen production projects. In summary, there is currently no device system that can efficiently purify and recycle electrolytic hydrogen production wastewater with low cost, simple operation, and equipment simplification. SUMMARY

[0004] The main purpose of the present application is to provide an electrolytic water hydrogen production wastewater purification and recycling system and method based on low-temperature distillation desalination, aiming to solve the problem of wastewater treatment generated by the current electrolytic water hydrogen production system, and propose a product water recycling logic means based on efficient purification means and water quality monitoring and control dual protection. The present application can efficiently achieve desalination treatment of hydrogen production wastewater, and realize product water recycling through technical guarantee means, reducing the front-end water consumption. In addition, the present application also has the potential to match the low-grade waste heat of the hydrogen production plant by coupling the low-temperature distillation technology, improving the energy utilization efficiency.

[0005] To achieve the above purpose, the present application provides an electrolytic water hydrogen production wastewater purification and recycling system based on low-temperature distillation desalination, which includes a raw water tank, a pure water system, a cooling system, a hydrogen production system, a wastewater tank, a low-temperature distillation system, a product water tank, a water quality detection system, an information collection and processing and alarm system, and a control system. The pure water system is used to produce pure water for the hydrogen production system, and the cooling system is used to exchange heat for the hydrogen production system; The water inlet end of the raw water pool is connected to the external water inlet pipeline and the product water pool reuse water pipeline, and the water outlet end is connected to the pure water system and the cooling system; The waste water pool receives concentrated brine from the pure water system and cooling waste water from the cooling system; The water quality detection system monitors the water quality indicators of the waste water pool and the product water pool in real time; The low-temperature distillation system is used to treat hydrogen production waste water with qualified water quality indicators, and the water inlet end is connected to the waste water pool, and the water outlet end is connected to the product water pool; The information collection and processing and alarm system is used to collect or calculate the working condition data of each component in the reuse system, process it for the control system to issue instructions, and trigger the alarm of the hydrogen production system and the low-temperature distillation system.

[0006] Further, the low-temperature distillation system includes a pressure regulating unit, a low-temperature evaporation unit, a crystallization separation unit, and a vapor condensation unit; The pressure regulating unit is used to control the formation of a negative pressure environment in the low-temperature distillation system; The low-temperature evaporation unit is used to distill the hydrogen production waste water under low-temperature conditions by heating with a heat source; The crystallization separation unit is used to discharge the solid residues in the waste water after low-temperature distillation out of the low-temperature distillation system; The vapor condensation unit is used to cool and liquefy the vapor after low-temperature distillation and send it to the product water pool.

[0007] Further, the reuse system also includes a waste heat supply system and an electric power supply system, both of which are connected to the low-temperature distillation system; the waste heat supply system is used to supply the recovered waste heat in the electrolytic water hydrogen production process to the low-temperature distillation system to provide the required heat source, and the electric power supply system is used to provide energy to maintain the low-temperature distillation system working when the heat source supplied by the waste heat supply system is insufficient.

[0008] Further, the pressure regulating unit includes a jet injection pump, which is used to inject high-speed working fluid to form a negative pressure environment in the low-temperature distillation system; The low-temperature evaporation unit includes a distillation device, and the heat source input end of the distillation device is connected to the waste heat output end of the waste heat supply system and the electric heater output end of the electric power supply system; The crystallization separation unit comprises a stirrer, a spiral scraper and a discharge device, the stirrer is arranged in the distillation device; the spiral scraper is arranged in the distillation device and is used for discharging the solid residue into the discharge device when the solid residue accumulation amount difference threshold value is reached; and the discharge device is used for discharging the solid residue out of the low-temperature distillation system. The steam condensation unit comprises a heat exchanger, which exchanges heat by externally conveying cold water to cool and liquefy the steam in the low-temperature distillation system.

[0009] Further, the water quality detection system comprises a wastewater pool detection module and a product water pool detection module. The wastewater pool detection module detects the water quality of the wastewater pool, and the water quality indexes include a total dissolved solids value , a chemical oxygen demand value , a hardness value , and a pH value , and in addition, the wastewater pool detection module is provided with red line values of the water quality indexes of the wastewater pool, including a total dissolved solids red line value , a chemical oxygen demand red line value , a hardness red line value , and pH upper and lower limit red line values , . The product water pool detection module detects the water quality of the product water pool, and the water quality indexes include a total dissolved solids value , a chemical oxygen demand value , a hardness value , and a pH value , and in addition, the product water pool detection module is provided with red line values of the water quality indexes of the product water pool, including a total dissolved solids red line value , a chemical oxygen demand red line value , a hardness red line value , and pH upper and lower limit red line values , .

[0010] Further, the information collection and processing system comprises information collection modules ①-⑥ and information processing modules a-c. The information collection module ① calculates the total water demand of the next day's hydrogen production system . The information collection module ② collects the water quantity in the product water pool on the current day . The information collection module ③ collects the water quantity in the wastewater pool on the current day . The information collection module ④ collects the water quality detection information of the wastewater pool and the product water pool on the current day by the water quality detection system. No. 5 information collection module: calculate the amount of distillable water that the low-temperature evaporation system can supply from the waste heat supply system on the current day ; No. 6 information collection module: collect the electricity price and the price of purchased water on the current day, and calculate the unit cost of desalinated water ; a information processing module: determine the amount of incoming water based on the information collected by the No. 1, No. 2, and No. 4 information collection modules ; b information processing module: determine the amount of purchased electricity based on the information collected by the No. 3, No. 4, No. 5, and No. 6 information collection modules ; c information processing module: determine whether to trigger an alarm based on the information collected by the No. 4 information collection module: if the water quality of the wastewater pool is not qualified, trigger an alarm for the hydrogen production system; if the water quality of the product water pool is not qualified, trigger an alarm for the low-temperature distillation system.

[0011] Further, the control system comprises: a first sub-unit: execute the instructions of the a information processing module to adjust the amount of incoming water and the amount of product water in the raw water pool; a second sub-unit: execute the instructions of the No. 4 information collection module to control the flow direction of wastewater in the wastewater pool; a third sub-unit: execute the instructions of the No. 4 information collection module to control the flow direction of product water in the product water pool; a fourth sub-unit: execute the instructions of the b information processing module to control the heat source supply scheduling of the waste heat supply system and the power supply system.

[0012] In another aspect of the present application, a method for purifying and recycling wastewater from electrolytic water hydrogen production based on low-temperature distillation desalination is provided, which is implemented by using the aforementioned system for purifying and recycling wastewater from electrolytic water hydrogen production, and comprises the following steps: Step S1: collect mixed wastewater Input the concentrated brine generated by the pure water system and the cooling wastewater generated by the cooling system into the wastewater pool; Step S2: wastewater pool water quality detection The water quality detection system detects the total dissolved solids value , the chemical oxygen demand value , the hardness value , and the pH value of the wastewater pool; the control system determines based on the collected wastewater pool water quality detection results, and when all the following conditions are met ; The control system generates a "wastewater quality qualified" instruction to enter step S3, otherwise it generates a "wastewater quality unqualified" instruction, which triggers an alarm for the hydrogen production system, and the hydrogen production system is suspended and starts maintenance work; Step S3, low-temperature distillation of wastewater: The qualified wastewater in the wastewater pool is sent to the low-temperature distillation system for wastewater treatment, and the treated product water is sent to the product water pool; Step S4, water quality detection of the product water pool: The water quality detection system detects the total dissolved solids value of the product water pool , the chemical oxygen demand value , the hardness value and the pH value ; the control system determines according to the collected water quality detection results of the product water pool, and when all the following conditions are met ; The control system generates a "product water quality qualified" instruction to enter step S5, otherwise a "product water quality unqualified" instruction is generated, which triggers an alarm of the low-temperature distillation system, and the low-temperature distillation system is suspended and starts maintenance work; Step S5, peak-shaving reuse of product water in the product water pool: The qualified product water obtained by low-temperature distillation on the same day is stored in the product water pool, and the product water is reused to the raw water pool the next day for hydrogen production.

[0013] Further, in step S3, low-temperature distillation of wastewater: the wastewater in the wastewater pool is sent to the low-temperature distillation system for wastewater treatment, and the treated product water is sent to the product water pool, comprising: The pressure regulation unit regulates the pressure of the low-temperature distillation system to form a negative pressure environment in the low-temperature distillation system; The low-temperature evaporation unit uses the heat source of the priority waste heat recovery system for heating, and uses the heat source of the power supply system for heating when insufficient, and boils and vaporizes the qualified wastewater sent by the wastewater pool under low-temperature conditions; The crystallization separation unit discharges the solid residues in the wastewater after low-temperature distillation out of the low-temperature distillation system; The steam condensation unit cools and liquefies the steam in the low-temperature distillation system, and sends the liquefied product water to the product water pool through a pipeline.

[0014] Further, the method further comprises step S6, determining the amount of incoming external water : Step S61, determining the amount of raw material water required by the system the next day and the amount of water required by the cooling water system according to the estimated hydrogen production of the electrolytic water hydrogen production plant the next day , to obtain the total water demand of the hydrogen production system the next day ; Step S62, determining the amount of incoming external water according to the product water pool water quality detection information: When the product water quality detection is unqualified, the amount of incoming external water = ; When the product water quality detection is qualified, the amount of external water inflow .

[0015] Compared with the prior art, the application has the following beneficial effects: The application creatively proposes a low-temperature distillation-based electrolytic water hydrogen production wastewater purification and reuse system and method, which not only fully utilizes the technical advantages of low-temperature distillation technology, such as low requirements for water quality, and coupling with low-grade waste heat, but also realizes the resource recycling of wastewater through a set of reuse system. Through the cooperation of the water quality detection system, the information collection and processing and alarm system and the control system, the safe and stable operation of the low-temperature distillation system is ensured, and the water quality of the electrolytic water hydrogen production system meets the standard.

[0016] The implementation of the application helps to reduce the pressure on local environmental protection caused by industrial wastewater generated by the electrolytic water hydrogen production project, and efficiently utilizes the product water after desalination for reuse, thereby reducing the demand for purchased water inflow of the hydrogen production plant and reducing the daily water purchase cost. It has important significance for the northwest region where water resources are relatively scarce and hydrogen production projects are relatively more. In addition, the low-temperature distillation system can utilize the potential of low-grade waste heat generated by other components of the hydrogen production plant, thereby reducing the energy consumption of the wastewater desalination part and improving the overall energy utilization efficiency of the hydrogen production plant. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Fig. 1 shows a structure schematic diagram of a low-temperature distillation-based electrolytic water hydrogen production wastewater purification and reuse system in an embodiment of the application; Figure 2 Fig. 2 shows a flow schematic diagram of a low-temperature distillation-based electrolytic water hydrogen production wastewater purification and reuse method in an embodiment of the application; Figure 3 Fig. 3 shows an optimized system architecture schematic diagram of the low-temperature distillation-based electrolytic water hydrogen production wastewater purification and reuse system and method. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and advantages of the application clearer, specific embodiments will be described in detail below with reference to the drawings.

[0019] The terms "first", "second", and the like in the specification and claims of the application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein.

[0020] It needs to be clear that wastewater treatment, detection and the rest of the system need a certain time in actual operation. In order to ensure that the product water can be safely and smoothly reused, there is a certain space-time dislocation between the hydrogen production water and the wastewater treatment. Therefore, the system and method take the day as the unit, and the product water of the nth day is used as the raw water for electrolysis water hydrogen production on the n+1 day after passing the detection.

[0021] Referring to Figure 1 , one aspect of an embodiment of the present application provides an electrolysis water hydrogen production wastewater purification and reuse system based on low-temperature distillation desalination, comprising a raw water pool, a pure water system, a cooling system, a hydrogen production system, a wastewater pool, a low-temperature distillation system, a product water pool, a water quality detection system, an information collection processing and alarm system, and a control system.

[0022] The raw water pool is a water storage pool or corresponding water storage equipment, the water inlet end of which is connected to the external water inlet pipeline and the product water pool inlet pipeline, for mixing and temporarily storing the hydrogen production plant purchased water and the high-quality product water inlet of the product water pool passing the detection, for subsequent use of the pure water system and the cooling system. The mixing part of the raw water pool is connected to the control system, for determining the mixing ratio of the external water and the product water.

[0023] The pure water system is a desalination system aiming to produce clean and pure raw water, which provides raw materials for electrolysis water hydrogen production. The system is generally equipped for electrolysis water hydrogen production, and is generally composed of a pretreatment module, a reverse osmosis membrane filtration module, and an auxiliary module. The pure water system produces hydrogen production pure water, which is transported to the hydrogen production system through the related pipeline for hydrogen production; at the same time, the byproduct concentrated brine is obtained, which is transported to the wastewater pool through the related pipeline for next step processing.

[0024] The cooling system is a cooling system for extracting heat generated by the electrolysis cell / compression pump process. The system is generally equipped for electrolysis water hydrogen production, and the core is generally a plate heat exchanger or a tube heat exchanger. The water in the raw water pool is sent to the cooling system through the delivery pipeline, and is discharged after heat exchange with the electrolysis cell, compression pump, etc. The wastewater generated in the cooling process is transported to the wastewater pool through the related pipeline for next step processing.

[0025] The hydrogen production system is generally composed of an equipment system with an electrolysis cell as the core, which is used for electrolysis of pure water to produce hydrogen and byproduct oxygen. The system is not the main part of the system designed by the present application, and is connected to the information collection processing and alarm system to provide daily hydrogen production working condition data.

[0026] The wastewater pool is a kind of water storage pool or corresponding water storage equipment, which is connected with the concentrated brine inlet pipeline of the pure water system and the cooling wastewater inlet pipeline, and is used for mixing and temporarily storing the wastewater generated by the hydrogen production system. The wastewater pool is connected with the control system, so as to determine whether the wastewater in the wastewater pool can reach the standard to enter the low-temperature distillation system, and if not, the control system controls the wastewater to be discharged to the external processing part.

[0027] The water quality detection system is a kind of system device based on water sample collection and water quality detection, which is used for detecting the water quality in the wastewater pool / product water pool, and transmitting the detected water quality indexes and detection conclusion to the information collection and alarm system connected therewith, so as to provide the control system with decision-making and control instruction.

[0028] The low-temperature distillation system is a kind of wastewater desalination treatment system, which is used for treating the hydrogen production wastewater qualified by the water quality detection, and is connected with the wastewater pool at the water inlet end and the product water pool at the water outlet end. The information collection and processing and alarm system is used for collecting or calculating the working condition data of each component in the recycling system, and processing the data, so as to provide the control system with instructions, and is also used for triggering the alarm of the hydrogen production system and the low-temperature distillation system. The control system receives the instruction information transmitted by the information collection and processing system, and controls the opening and closing of each component and the amount of each component.

[0029] In a preferred embodiment of the present application, the recycling system further comprises a waste heat supply system and a power supply system. The waste heat supply system is a kind of equipment system for recovering and reusing the waste heat generated in the industrial production process of the hydrogen production plant and surrounding facilities, and is connected with the low-temperature distillation system to provide the heat source required for distillation, and is connected with the information collection and processing and alarm system to provide the predicted waste heat energy value that can be collected the next day. The power supply system is connected with the power grid at the upstream and connected with the low-temperature distillation system at the downstream, and provides energy to maintain the operation of the low-temperature distillation system when the waste heat energy is insufficient, and is connected with the information collection and processing and alarm system to provide information such as electricity price for the control system to make decisions.

[0030] In a preferred embodiment of the present application, the low-temperature distillation system comprises a pressure regulation unit, a low-temperature evaporation unit, a crystallization separation unit and a steam condensation unit. The pressure regulation unit comprises a jet injection pump, the low-temperature evaporation unit comprises a distillation device, the crystallization separation unit comprises a stirrer, a spiral scraper and a discharge device, and the steam condensation unit comprises a heat exchanger.

[0031] The pressure regulation unit sprays high-speed working fluid through the jet injection pump to form a negative pressure tending to be a vacuum (-93kpa~-98kpa) in the distillation device, so as to help the wastewater to be sucked into the distillation device, and the negative pressure environment in the distillation device also promotes the subsequent wastewater to be boiled and vaporized at a low temperature (45℃-50℃).

[0032] The low-temperature evaporation unit distills the hydrogen production wastewater at a low temperature (45-50°C) in the distillation device by heating with a heat source. The heat source can be provided in two ways: one is to provide the system with low-grade waste heat from the hydrogen production site, which is connected to the low-temperature evaporation unit, thereby realizing waste heat distillation; the other is to supply the system with electricity, which uses the energy of an electric heater to supply heat for the distillation. The steam generated during the distillation process is connected to the steam condensing unit, and because of the low-pressure environment, wastewater is continuously sucked into the distillation device to maintain the continuous distillation process. The unit is connected to the control system to control the operation mode of the waste heat supply system / electricity supply system.

[0033] As the low-temperature distillation process continues, impurities and waste salt in the wastewater are continuously precipitated in the distillation device. The solids on the surface of the distillation device are removed by the continuous stirring of the stirrer in the crystallization separation unit, and the precipitated salt residue is removed in time to avoid fouling. When the discharge standard is reached, the distillation device opens the discharge port, and the solids are pushed to the discharge device by the spiral scraper in a directional manner. The discharge device discharges the solids to the outside of the low-temperature distillation system. After the discharge, the discharge device is automatically reset and enters the next cycle. The accumulated solid residue can be outsourced for solid waste treatment. The steam condensing unit uses a shell-and-tube heat exchanger, for example, to exchange heat with external cold water, causing the steam to rapidly cool and liquefy. The condensed water is discharged into the product water tank through the connecting pipeline.

[0034] In a preferred embodiment of the present application, the water quality detection system includes a wastewater pool detection module and a product water pool detection module. The water quality detection system has preset water quality index standard values for wastewater / product water, including total dissolved solids (TDS), chemical oxygen demand (COD), pH, hardness (TH), and key ion concentration (specifically set according to the product process of the hydrogen production plant and the actual situation).

[0035] Specifically, the wastewater pool detection module detects the water quality of the wastewater pool, and the detection indexes include the total dissolved solids value , the chemical oxygen demand value , the hardness value , and the pH value . In addition, the wastewater pool detection module has preset red line values for the water quality indexes of the wastewater pool, including the total dissolved solids red line value , the chemical oxygen demand red line value , the hardness red line value , and the upper and lower limit red line values for the pH value , . The control system determines the water quality detected by the wastewater pool in real time, and when all the following conditions are met: , the control system determines that the water quality of the wastewater pool is qualified, otherwise the water quality is unqualified. When the water quality is unqualified, the control system flows the wastewater of the wastewater pool to the outsourcing treatment pipeline.

[0036] Specifically, the product pool detection module detects the water quality of the product pool, and the water quality indexes include the total dissolved solids value , the chemical oxygen demand value , the hardness value , and the pH value . In addition, the product pool detection module presets the red line value of the product pool water quality index, including the total dissolved solids red line value , the chemical oxygen demand red line value , the hardness red line value , and the pH upper and lower limit red line value , . The control system determines the water quality detected by the product pool in real time, and when all the following conditions are met: , the control system determines that the water quality of the product pool is qualified, otherwise the water quality is unqualified. When the water quality is unqualified, the control system will make a second determination, and if it meets the discharge standard, a secondary instruction "product water quality does not meet the standard, can be discharged" is generated; if it exceeds the discharge red line, a secondary instruction "product water quality does not meet the standard, needs outsourcing treatment" is generated.

[0037] In a preferred embodiment of the present application, the information collection and processing system comprises information collection modules ①-⑥ and information processing modules a-c; The ① information collection module calculates the total water demand of the next day hydrogen production system , and the specific calculation process is as follows: Estimate the hydrogen production of the hydrogen production plant on the next day (n+1 day) , according to the pure water conversion ratio determined by the actual technical path of the plant process , and the raw water production pure water conversion ratio , determine the required amount of raw water for the pure water system satisfies: (1); wherein, is the raw water required for the pure water system, is the pure water conversion ratio, is the raw water production pure water conversion ratio; According to the conversion ratio of cooling water and hydrogen production , determine the cooling system water consumption satisfies: (2); wherein, is the cooling system water consumption, Conversion ratio of cooling water and hydrogen production.

[0038] Therefore, the total water demand of the pure water system and the cooling system on the next day (n+1 day) can be determined, that is, the total water demand of the hydrogen production system Satisfies: (3).

[0039] ② Information collection module: collect the water quantity in the product water tank on the day ; ③ Information collection module: collect the water quantity in the waste water tank on the day ; ④ Information collection module: collect the water quality detection information of the waste water tank and the product water tank by the water quality detection system on the day, including water quality index information and detection conclusion qualified or unqualified; ⑤ Information collection module: calculate the distillable water quantity that the waste heat supply system can supply to the low-temperature evaporation system on the day , the specific calculation formula is: (4); Among them, is the equivalent of waste heat that can be provided by the hydrogen production plant and surrounding industries on the day (n day) (which can be converted according to actual working conditions), is the heat transfer loss ratio, which is related to the actual use system process, equipment, etc. of the hydrogen production plant; is the unit heat distillable water quantity conversion coefficient, the calculation formula is: (5); Among them, = - , is the inlet water temperature, is the distillation temperature, is the latent heat of vaporization, and c is the specific heat capacity of water.

[0040] ⑥ Information collection module: collect the electricity price information and the information of the purchased water price (unit cost is ) on the day (n day), which is used for subsequent calculation to determine whether it is necessary to buy electricity for desalination and the corresponding electricity purchase quantity. Considering the time-of-use electricity price, if the electricity price per kilowatt-hour collected is , the electricity heat conversion loss ratio , then according to the content derived in the No. 5 module, the unit cost of desalination water (which is the electricity cost required to produce one ton of low-temperature distillation desalination water, that is, electricity fee) is: (6), wherein, is the electricity price per kilowatt-hour, is the ratio of electric heat conversion loss, is the conversion coefficient of unit heat distillable water. a number of information processing module: comprehensive information collected by the ①, ②, ④ information collection module, determine the amount of incoming water ; 1) when the ④ module receives the "product water quality unqualified" instruction, ; 2) when the ④ module receives the "product water quality qualified" instruction, .

[0041] b number of information processing module: comprehensive information collected by the ③, ④, ⑤, ⑥ information collection module, determine the amount of purchased electricity ; When the ④ module receives the "waste water quality unqualified" instruction, there is no waste water flowing into the low temperature distillation system, and the distillation system does not work, =0; When the ④ module receives the "waste water quality qualified" instruction, 1) ≤ , the amount of waste water that can be distilled by waste heat exceeds the amount of waste water that needs to be distilled, and there is no need to purchase electricity to supplement energy, at this time, . 2) > , and ≤ , at this time, the heat provided by the waste heat is not enough to support the distillation of all waste water, and the cost of producing product water by low temperature distillation is lower than the price of imported water, so the energy should be purchased to supplement the insufficient energy for desalination of pure water, at this time, (7); Among them, is the amount of purchased electricity, is the equivalent of waste heat that can be provided by the hydrogen production plant and surrounding industries on the day (n day) (which can be converted according to the actual working condition experience), is the ratio of heat transfer loss, which is related to the actual use system process, equipment, etc. of the hydrogen production plant, = - , is the water temperature, is the distillation temperature, is the latent heat of vaporization, c is the specific heat capacity of water, is the ratio of electric heat conversion loss.

[0042] 3) > ,and At this point, the waste heat provided is insufficient to support the distillation of all wastewater, but the cost of producing product water through low-temperature distillation is higher than the price of imported water. Therefore, based on actual production needs and experience (electricity price fluctuations, the amount of waste heat available the next day, the amount of hydrogen production wastewater the next day, etc.), a manual instruction should be input to determine the required electricity purchase. .

[0043] Information processing module C: Based on the information collected by information collection module ④, determine whether to trigger an alarm: If the water quality of the wastewater pool fails the test, trigger an alarm in the hydrogen production system; if the water quality of the product pool fails the test, trigger an alarm in the low-temperature distillation system.

[0044] In a preferred embodiment of the present invention, the control system includes: First subunit: Executes instructions from information processing module A to regulate the inflow of external water and product water into the raw water tank: Upstream, it connects to information collection and processing system module A to collect information on external water demand and product water inflow; downstream, it connects to the raw water tank to control the opening and closing of the two water supply channels and the water supply volume.

[0045] The second subunit executes the instructions of information collection module ④ to control the flow of wastewater in the wastewater tank: upstream, it connects to information collection and processing system module ④ to collect wastewater quality-related information instructions; downstream, it connects to the wastewater tank to control the channel switch and the flow rate for wastewater to be transported into the low-temperature distillation system or sent to external processing. The third subunit executes the instructions of information collection module ④ to control the flow direction of product water in the product water tank: upstream, it connects to information collection and processing system module ④ to collect instructions related to product water quality; downstream, it connects to the product water tank to control the channel switch and the flow rate of product water to enter the raw water tank or to be discharged / outsourced for treatment.

[0046] The fourth subunit executes the instructions of information processing module B and controls the heat source supply scheduling of the waste heat supply system and the power supply system: upstream, it connects to information collection and processing module B to collect relevant instructions such as electricity purchase; downstream, it connects to the low-temperature distillation system (low-temperature evaporation unit) to execute relevant electricity purchase operations (if necessary) and control the switching and transmission of energy values ​​of the two channels of energy supply from the waste heat collection system and the power supply system.

[0047] A second aspect of the present invention provides a method for purifying and reusing wastewater from water electrolysis for hydrogen production based on low-temperature distillation and desalination. This method utilizes the aforementioned wastewater purification and reuse system for water electrolysis for hydrogen production, the specific process of which is illustrated in the schematic diagram below. Figure 2 This includes the following steps: Step S1, Collection of mixed wastewater: The collected fresh water is used as the input of the pure water / cooling system of the hydrogen production system, and the concentrated brine generated by the pure water system and the cooling wastewater generated by the cooling system are input into the wastewater pool; Step S2, wastewater pool water quality detection: The water quality detection system detects the total dissolved solids value of the wastewater pool water quality , the chemical oxygen demand value , the hardness value and the pH value ; the control system determines according to the collected wastewater pool water quality detection results, when all the following conditions are met ; The control system generates a "wastewater quality qualified" instruction to enter step S3, otherwise it generates a "wastewater quality unqualified" instruction, which triggers the hydrogen production system alarm, the hydrogen production system is suspended and the maintenance work is started, and the wastewater in the wastewater pool is outsourced for treatment; Step S3, low-temperature distillation of wastewater: The qualified wastewater in the wastewater pool is sent to the low-temperature distillation system for wastewater treatment, and the treated product water is sent to the product water pool, including: the pressure control unit controls the pressure of the low-temperature distillation system to form a negative pressure environment; the low-temperature evaporation unit uses the heat source of the priority waste heat recovery system for heating, and uses the heat source of the power supply system for heating when insufficient, and the qualified wastewater from the wastewater pool is boiled and vaporized under low-temperature conditions; the crystallization separation unit discharges the solid residues in the low-temperature distilled wastewater outside the low-temperature distillation system; the steam condensation unit cools and liquefies the steam in the low-temperature distillation system, and sends the liquefied product water to the product water pool through the pipeline.

[0048] Step S4, product water pool water quality detection: The water quality detection system detects the total dissolved solids value of the product water pool water quality , the chemical oxygen demand value , the hardness value and the pH value ; the control system determines according to the collected product water pool water quality detection results, when all the following conditions are met ; The control system generates a "product water quality qualified" instruction to enter step S5, otherwise it generates a "product water quality unqualified" instruction, which triggers the low-temperature distillation system alarm, the low-temperature distillation system is suspended and the maintenance work is started, and the product water in the product water pool is discharged or outsourced for treatment; Step S5, peak-shaving reuse of product water in the product water pool: The qualified product water obtained by low-temperature distillation on the same day is stored in the product water pool, and the product water is reused in the raw water pool the next day for hydrogen production.

[0049] Step S6, determination of the amount of incoming external water Specifically, it includes the following steps: Step S61: Based on the estimated hydrogen production volume of the water electrolysis hydrogen production plant for the next day. Determine the amount of raw water required by the system the next day. Water consumption required for cooling water system The total water intake demand of the hydrogen production system for the next day was obtained. ; Step S62: Determine the inflow volume of external water based on the water quality test information of the product pool. : When the product's water quality fails the test, the amount of external water entering the system will be reduced. = ; When the product's water quality test is qualified, the external water inflow rate... .

[0050] Reference Figure 3 The present invention provides a system and method for purifying and reusing wastewater from water electrolysis hydrogen production based on low-temperature distillation desalination, achieving the following optimizations: 1. The present invention uses low-temperature distillation technology to purify wastewater during the water electrolysis hydrogen production process. This purified wastewater can be directly reused in water electrolysis hydrogen production, significantly reducing wastewater pollution and the amount of water purchased for hydrogen production. 2. The present invention couples the waste heat from the plant as a heat source for the low-temperature distillation wastewater treatment, maximizing energy efficiency and reducing input costs. 3. The water electrolysis hydrogen production wastewater purification and reuse system of the present invention employs intelligent control, utilizing information collection and processing, alarm systems, and control systems for comprehensive judgment, achieving stable operation of the water electrolysis hydrogen production wastewater purification and reuse system and optimizing cost and energy utilization.

[0051] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. The present invention can also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of the present invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A system for purifying and reusing wastewater from hydrogen production via water electrolysis based on low-temperature distillation and desalination, characterized in that, It includes raw water tank, pure water system, cooling system, hydrogen production system, wastewater tank, low temperature distillation system, product water tank, water quality testing system, information collection, processing and alarm system, and control system; The pure water system is used to produce hydrogen-producing pure water for the hydrogen production system, and the cooling system is used to exchange heat for the hydrogen production system. The inlet of the raw water tank is connected to the external water inlet pipe and the product water tank return water pipe, and the outlet is connected to the pure water system and the cooling system. The wastewater tank receives concentrated brine from the pure water system and cooling wastewater from the cooling system. The water quality testing system monitors the water quality indicators of the wastewater pool and the product pool in real time. The low-temperature distillation system is used to treat hydrogen production wastewater that has passed the water quality index test. Its inlet is connected to the wastewater pool and its outlet is connected to the product water pool. The information collection, processing, and alarm system is used to collect or calculate the operating condition data of each component in the reuse system, and process it to provide instructions for the control system to issue commands. It is also used to trigger alarms in the hydrogen production system and the cryogenic distillation system.

2. The electrolytic water hydrogen production wastewater purification and reuse system based on low-temperature distillation and desalination according to claim 1, characterized in that, The low-temperature distillation system includes a pressure control unit, a low-temperature evaporation unit, a crystallization separation unit, and a steam condensation unit; The pressure control unit is used to control the formation of a negative pressure environment within the low-temperature distillation system. The low-temperature evaporation unit is used to distill hydrogen production wastewater at low temperatures by using a heat source. The crystallization separation unit is used to discharge the solid residue from the wastewater after low-temperature distillation outside the low-temperature distillation system; The steam condensation unit is used to cool and liquefy the steam after low-temperature distillation and then send it into the product water tank.

3. The electrolytic water hydrogen production wastewater purification and reuse system based on low-temperature distillation and desalination according to claim 2, characterized in that, The reuse system also includes a waste heat supply system and a power supply system, both of which are connected to the cryogenic distillation system. The waste heat supply system is used to supply the waste heat recovered during the production process of the water electrolysis hydrogen production plant to the cryogenic distillation system to provide the required heat source. The power supply system is used to provide energy to maintain the operation of the cryogenic distillation system when the heat source supplied by the waste heat supply system is insufficient.

4. The electrolytic water hydrogen production wastewater purification and reuse system based on low-temperature distillation desalination according to claim 3, characterized in that, The pressure control unit includes a jet pump, which is used to jet high-speed working fluid to create a negative pressure environment within the cryogenic distillation system. The low-temperature evaporation unit includes a distillation device, the heat source input end of which is connected to the waste heat output end of the waste heat supply system and the electric heater output end of the power supply system. The crystallization separation unit includes a stirrer, a spiral scraper, and a discharge device. The stirrer is located inside the distillation apparatus. The spiral scraper is located inside the distillation apparatus and is used to directionally discharge the solid residue into the discharge device when the accumulated amount of solid residue exceeds a threshold. The discharge device is used to discharge the solid residue outside the low-temperature distillation system. The steam condensation unit includes a heat exchanger, which exchanges heat through externally supplied cold water to cool and liquefy the steam in the low-temperature distillation system.

5. The electrolytic water hydrogen production wastewater purification and reuse system based on low-temperature distillation and desalination according to claim 1, characterized in that, The water quality testing system includes a wastewater pool testing module and a product water pool testing module; The wastewater pool testing module tests the water quality of the wastewater pool, and the water quality indicators include total dissolved solids. Chemical oxygen demand value Hardness value pH value In addition, the wastewater pool detection module has preset red line values ​​for wastewater pool water quality indicators, including the total dissolved solids red line value. Chemical oxygen demand (COD) red line value Hardness red line value The upper and lower limits of pH (red lines) are respectively , ; The product water tank testing module tests the water quality of the product water tank, and the water quality indicators include total dissolved solids. Chemical oxygen demand value Hardness value pH value In addition, the product water tank testing module has preset red line values ​​for water quality indicators in the product water tank, including the red line value for total dissolved solids. Chemical oxygen demand (COD) red line value Hardness red line value The upper and lower limits of pH (red lines) are respectively , .

6. The electrolytic water hydrogen production wastewater purification and reuse system based on low-temperature distillation desalination according to claim 1, characterized in that, The information collection and processing system includes information collection modules ① to ⑥ and information processing modules a to c. Information collection module ①: Calculates the total water demand for the hydrogen production system the following day. ; Information collection module ②: Collects the water volume in the product pool on the current day. ; Information collection module ③: Collects the daily water volume in the wastewater tank. ; Information collection module ④: Collects water quality testing information from the wastewater pool and product pool of the water quality testing system on the same day; Information collection module ⑤: Calculates the amount of distillable water that the waste heat supply system can supply to the low-temperature evaporation system on the current day. ; Information Collection Module 6: Collects daily electricity price information and purchased water price, and calculates the unit cost of desalinated water. ; Information processing module A: Combines information collected by information collection modules ①, ②, and ④ to determine the inflow of external water. ; Information processing module B: Combines information collected by information collection modules ③, ④, ⑤, and ⑥ to determine the amount of electricity purchased externally. ; Information processing module C: Based on the information collected by information collection module ④, determine whether to trigger an alarm: If the water quality of the wastewater pool fails the test, trigger an alarm in the hydrogen production system; if the water quality of the product pool fails the test, trigger an alarm in the low-temperature distillation system.

7. The electrolytic water hydrogen production wastewater purification and reuse system based on low-temperature distillation desalination according to claim 6, characterized in that, The control system includes: First subunit: Executes instructions from information processing module A to adjust the inflow of external water and product water into the raw water tank; Second subunit: Executes the instructions of information collection module ④ to control the flow direction of wastewater in the wastewater pool; Third subunit: Executes the instructions of information collection module ④ to control the flow direction of product water in the product pool; Fourth subunit: Executes instructions from information processing module b to control the heat source supply scheduling of the waste heat supply system and the power supply system.

8. A method for purifying and reusing wastewater from water electrolysis for hydrogen production based on low-temperature distillation and desalination, implemented using the wastewater purification and reuse system for water electrolysis for hydrogen production as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1, Collection of mixed wastewater: The concentrated brine produced by the pure water system and the cooling wastewater produced by the cooling system are fed into the wastewater tank; Step S2, Wastewater pool water quality testing: The water quality testing system measures the total dissolved solids (TDS) value of wastewater in the wastewater pond. Chemical oxygen demand value Hardness value pH value The control system determines the appropriate action based on the collected water quality test results from the wastewater tank. The system will activate when all of the following conditions are met. ; If the control system generates a "wastewater quality qualified" command, it will proceed to step S3; otherwise, it will generate a "wastewater quality unqualified" command, which will trigger an alarm in the hydrogen production system, causing the hydrogen production system to suspend and start maintenance work. Step S3, Low-temperature distillation wastewater: The qualified wastewater from the wastewater tank is sent to the low-temperature distillation system for wastewater treatment, and the treated product water is sent to the product water tank. Step S4, Water quality testing in the product pool: The water quality testing system measures the total dissolved solids (TDS) value in the product's water tank. Chemical oxygen demand value Hardness value pH value The control system determines the appropriate action based on the collected water quality test results from the product pool. The system will proceed as follows: [The following conditions must be met for the system to function correctly.] ; The control system generates a "product water quality qualified" command and proceeds to step S5; otherwise, it generates a "product water quality unqualified" command, which triggers an alarm in the low-temperature distillation system, causing the low-temperature distillation system to pause and start maintenance work. Step S5: Peak-shifting reuse of product water from the product water tank: The qualified product water obtained from low-temperature distillation on the same day is stored in the product water pool, and then reused in the raw water pool the next day for hydrogen production.

9. The method for purifying and reusing hydrogen production wastewater from water electrolysis based on low-temperature distillation and desalination according to claim 8, characterized in that, In step S3, low-temperature distillation wastewater: the wastewater from the wastewater tank is sent to the low-temperature distillation system for wastewater treatment, and the treated product water is sent to the product water tank, including: The pressure control unit regulates the pressure of the cryogenic distillation system to create a negative pressure environment. The low-temperature evaporation unit is heated by a priority waste heat recovery system. When the heat source is insufficient, the heat source is supplied by an electric power supply system. The qualified wastewater sent from the wastewater pool is boiled and vaporized at a low temperature. The crystallization separation unit discharges the solid residue from the wastewater after low-temperature distillation outside the low-temperature distillation system; The steam condensation unit cools and liquefies the steam in the low-temperature distillation system, and then sends the liquefied product water into the product water tank through pipelines.

10. The method for purifying and reusing hydrogen production wastewater from water electrolysis based on low-temperature distillation and desalination according to claim 8, characterized in that, The method further includes step S6, determining the inflow of external water. : Step S61: Based on the estimated hydrogen production volume of the water electrolysis hydrogen production plant for the next day. Determine the amount of raw water required by the system the next day. Water consumption required for cooling water system The total water intake demand of the hydrogen production system for the next day was obtained. ; Step S62: Determine the inflow volume of external water based on the water quality test information of the product pool. : When the product's water quality fails the test, the amount of external water entering the system will be reduced. = ; When the product's water quality test is qualified, the external water inflow rate... .

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