Sea water electrolysis and salt electrolysis series-parallel hydrogen production system and method based on seawater

Abstract

The invention relates to a seawater-based water electrolysis and salt electrolysis series-parallel hydrogen production system and a seawater-based water electrolysis and salt electrolysis series-parallel hydrogen production method. The device comprises an electrolyzed water coupling low-temperature distillation integrated system, a concentrated seawater treatment unit and a hydrogen purification unit, wherein the electrolyzed water coupling low-temperature distillation integrated system comprises an alkaline electrolytic bath unit, an oxygen separation cooling unit, a hydrogen separation cooling unit, an alkali liquor circulating filtering unit and a seawater desalination unit. Salt is directly extracted from concentrated seawater generated by the electrolyzed water coupling low-temperature distillation integrated system, NaOH, chlorine and hydrogen are prepared through the chlor-alkali electrolytic cell, the seawater utilization rate is higher, the device is arranged on the sea or on the sea, the overall occupied area is small, and efficient resource utilization of seawater is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of seawater development and utilization, and in particular to a system and method for producing hydrogen by hybrid electrolysis of seawater and electrolysis of salt. Background Art

[0002] There are three methods for industrial production of caustic soda: causticization, electrolysis and ion exchange membrane. The ion exchange membrane method is to purify the raw salt and then refine the brine in the traditional way. The first refined brine is filtered through a microporous sintered carbon tubular filter and then refined through a chelating ion exchange resin tower to reduce the calcium and magnesium content in the brine to below 0.002%. The second refined brine is electrolyzed to generate chlorine in the anode chamber. The Na+ in the brine in the anode chamber enters the cathode chamber through the ion membrane and reacts with the OH in the cathode chamber to generate sodium hydroxide. The H+ is directly discharged on the cathode to generate hydrogen.

[0003] The existing caustic soda preparation method has complex and diverse technical routes, but the overall device is connected by pipelines, the overall footprint is large, and the utilization rate of the plant is low. In addition, most of the generated hydrogen is safely discharged, resulting in a waste of resources.

[0004] Hydrogen energy is regarded as the clean energy with the greatest development potential in the 21st century. Using green electricity generated by renewable energy such as solar energy and wind energy to drive the electrolysis of water to produce hydrogen is of great significance to solving the problem of energy shortage and achieving the "dual carbon" goal. Among the current water electrolysis hydrogen production technologies, alkaline water electrolysis has a low cost and relatively mature technology. It is the most widely industrialized hydrogen production technology and occupies a dominant position. The "Global Water Use Report for Hydrogen Production" released by the International Renewable Energy Agency (IRENA) shows that the current mainstream hydrogen production methods in the world require fresh water, mainly concentrated in the two major processes of hydrogen production and cooling. About 32.2 liters of fresh water are required to produce 1 kilogram of blue hydrogen. In the production of green hydrogen, the amount of fresh water consumed by the alkaline water electrolysis hydrogen production process to produce 1 kilogram of hydrogen is estimated to be 22.3 liters. However, global fresh water resources are extremely limited, and the large-scale promotion and application of water electrolysis hydrogen production technology will undoubtedly aggravate the problem of fresh water shortage. Summary of the invention

[0005] In response to the technical problems raised above, a system and method for producing hydrogen by hybrid electrolysis of seawater and electrolysis of common salt is provided.

[0006] The technical means adopted by the present invention are as follows:

[0007] A hybrid hydrogen production system based on seawater electrolysis and salt electrolysis, comprising: an electrolysis water coupled low-temperature distillation integrated system, a concentrated seawater processing unit and a hydrogen purification unit, wherein the electrolysis water coupled low-temperature distillation integrated system comprises an alkaline electrolyzer unit, an oxygen separation cooling unit, a hydrogen separation cooling unit, an alkali solution circulation filtration unit and a seawater desalination unit, wherein the electrolysis water coupled low-temperature distillation integrated system collects seawater to be processed, and the seawater desalination unit is used to heat the seawater, remove impurities from the steam and condense to produce fresh water and concentrated seawater to be collected; the output end of the seawater desalination unit is connected to the alkaline electrolysis unit. The alkaline electrolytic cell unit is connected, the fresh water in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current, the hydrogen and alkali liquid enter the hydrogen separation cooling unit, and the oxygen and alkali liquid enter the oxygen separation cooling unit; the alkali liquid circulation filtration unit is used to complete the forced circulation of alkali liquid in the alkaline electrolytic cell unit and the hydrogen separation cooling unit and the oxygen separation cooling unit; the product of the seawater desalination unit includes concentrated seawater, which is directly introduced into the concentrated seawater treatment unit, and the concentrated seawater treatment unit is used to purify the concentrated seawater, and the purified concentrated seawater is used to prepare NaOH solution, chlorine and hydrogen through the chlor-alkali industry.

[0008] Furthermore, it also includes a hydrogen purification cooling unit, which is arranged inside the water electrolysis coupled low-temperature distillation integrated system or outside the water electrolysis coupled low-temperature distillation integrated system, and is used to purify the hydrogen; when it is arranged inside the water electrolysis coupled low-temperature distillation integrated system, its input end is connected to the hydrogen separation cooling unit; when it is arranged outside the water electrolysis coupled low-temperature distillation integrated system, its input end is respectively connected to the hydrogen separation cooling unit and the hydrogen outlet of the concentrated seawater treatment unit.

[0009] Furthermore, the concentrated seawater treatment unit includes a crystallization purification unit, a refined brine configuration unit, a chlor-alkali electrolytic cell and a drying unit. The crystallization purification unit is connected to an electrolytic water coupled low-temperature distillation integrated system, and is used to complete the crystallization purification of concentrated seawater by evaporation. The refined brine configuration unit is connected to the crystallization purification unit, and the crystallization purification unit is also connected to the fresh water outlet of the electrolytic water coupled low-temperature distillation integrated system, and refined brine is prepared by outputting fresh water and crystallized salt in a preset proportion. The output end of the refined brine configuration unit is connected to a chlor-alkali electrolytic cell, and the chlor-alkali electrolytic cell is used to prepare NaOH solution, chlorine and hydrogen. The drying unit is arranged at the chlorine outlet of the chlor-alkali electrolytic cell, and is used to dry the wet chlorine. The NaOH solution is discharged through the NaOH solution outlet of the chlor-alkali electrolytic cell, and NaOH is prepared by evaporation and crystallization. Hydrogen is discharged through the hydrogen outlet of the chlor-alkali electrolytic cell.

[0010] Furthermore, the seawater enters a seawater desalination unit or a hydrogen separation cooling unit or an oxygen separation cooling unit.

[0011] Furthermore, the hydrogen outlet of the alkaline electrolyzer module is connected to the hydrogen separation cooling unit, the oxygen outlet of the alkaline electrolyzer module is connected to the oxygen separation cooling unit, the alkali liquid inlet of the alkaline electrolyzer module is connected to the seawater desalination unit, the oxygen separation cooling unit separates oxygen and alkali liquid by a gas-liquid separation method, the hydrogen separation cooling unit separates hydrogen and alkali liquid by a gas-liquid separation method, the hydrogen outlet of the hydrogen separation cooling unit is connected to the hydrogen purification cooling unit, the alkali liquid outlet of the oxygen separation cooling unit and the alkali liquid outlet of the hydrogen separation cooling unit are both connected to the alkali liquid circulation filtration unit to provide high-temperature alkali liquid to be cooled, and the fresh water outlet of the seawater desalination unit is connected to the hydrogen separation cooling unit; the device arranged outside the electrolysis water coupled low-temperature distillation integrated system is specifically the rear end of the chlor-alkali electrolyzer.

[0012] Furthermore, the seawater desalination unit includes a device cylinder, a vacuum system, a condenser, a water receiving plate, and a wire mesh separator. The device cylinder is provided with a vacuum system connection port, a seawater inlet port, a concentrated seawater outlet port, a fresh water outlet, and an alkali solution circulation pipe. The device cylinder is connected to the vacuum system through the vacuum system connection port, and is directly connected to seawater or an oxygen separation cooling unit / hydrogen separation cooling unit through the seawater inlet port. The concentrated seawater outlet port is used to collect concentrated seawater. The alkali solution circulation pipe is used to exchange heat between high-temperature alkali solution and seawater, reduce the temperature of the alkali solution, and make the seawater reach the evaporation temperature and evaporate into water vapor. The water vapor is condensed by the condenser. The water receiving plate is used to receive condensed water droplets, and its output end is connected to the fresh water outlet. A wire mesh separator is arranged in the device cylinder, which is used to separate larger droplets and impurities in the water vapor.

[0013] Furthermore, the alkaline electrolytic cell used specifically includes a cathode end plate and an anode end plate, and at least one electrolytic cell unit composed of a bipolar plate is arranged between the cathode end plate and the anode end plate; the cathode end plate, the bipolar plate and the anode end plate all include a plate body, and positioning holes, fastening holes, an alkali solution inlet, a gas outlet (i.e., an alkali solution and hydrogen outlet or an alkali solution and oxygen outlet) and a guide component are arranged at corresponding positions of each plate; the guide components of the cathode end plate and the anode end plate are opened on the inner side close to the bipolar plate, and a flow channel for connecting the alkali solution inlet and the gas outlet is opened in the middle position of the end surface of the plate body, and the guide component divides the flow channel in a preset form, and the guide component specifically includes a blocking mechanism and a guide mechanism, and the guide mechanism is arranged on the alkali solution inlet side and the gas outlet side, and the blocking mechanism is a plurality of array-distributed nipples, including a central nipple and an annularly distributed nipple with the central nipple as the center and arranged in its circumference at a preset interval.

[0014] Furthermore, the cathode end plate, the bipolar plate and the anode end plate are divided into a plate body and a plate frame by sealing grooves. The plate body is arranged inside the plate frame. There are multiple groups of sealing grooves in a circumferential direction. The sealing grooves protrude from the plate body and the plate frame by a preset distance. A number of positioning holes are opened on the plate body, and a number of mounting holes are opened on the plate frame along its circumference.

[0015] Furthermore, the flow guiding mechanism is a plurality of partition plates arranged at intervals perpendicular to the alkali solution inlet and the gas outlet. By arranging the partition plates, the fluid is evenly dispersed to enter / flow out of the flow channel between the mastoids.

[0016] Furthermore, grooves for installing upper gaskets and lower gaskets are provided on the end surfaces of the alkali solution inlet and the gas outlet, and the shapes of the grooves match the gaskets.

[0017] Furthermore, a support column is provided at the bottom of the board frame of the preset board.

[0018] A method for producing hydrogen by hybrid electrolysis of seawater and salt, comprising the following steps:

[0019] The water electrolysis coupled cryogenic distillation integrated system is connected to the seawater source to start the hybrid hydrogen production of seawater electrolysis and salt electrolysis, among which,

[0020] The seawater is directly transported to the desalination unit for fresh water production and concentrated seawater separation, or enters the desalination unit after passing through the oxygen separation cooling unit and the hydrogen separation cooling unit. The seawater can play an auxiliary cooling role in the oxygen separation cooling unit and the hydrogen separation cooling unit.

[0021] Fresh water in the alkaline electrolyser unit is decomposed into hydrogen and oxygen by direct current;

[0022] The oxygen outlet of the alkaline electrolyzer unit transports oxygen and alkaline solution to the oxygen separation cooling unit for gas-liquid separation;

[0023] The hydrogen outlet of the alkaline electrolyzer unit transports hydrogen and alkaline solution to the hydrogen separation cooling unit for gas-liquid separation;

[0024] The alkali liquid circulation filtration unit extracts the alkali liquid from the oxygen separation cooling unit and the hydrogen separation cooling unit, cools it in the seawater desalination unit, and finally transports it to the alkaline electrolyzer unit to complete the cooling and forced circulation of the alkali liquid;

[0025] The heat emitted by the alkali solution during cooling in the seawater desalination unit is used to heat the seawater under negative pressure to produce fresh water. The produced fresh water is transported to the hydrogen separation cooling unit to supplement the raw fresh water used for electrolysis, and also assists in hydrogen scrubbing and cooling.

[0026] The crystallization purification of concentrated seawater is completed by evaporation through the crystallization purification unit. The refined brine configuration unit prepares refined brine through a preset ratio of fresh water and crystal salt. The refined brine is transported to the chlor-alkali electrolyzer to prepare NaOH solution, chlorine and hydrogen. The wet chlorine is dried by the drying unit. The NaOH solution discharged from the NaOH solution outlet of the chlor-alkali electrolyzer is used to prepare NaOH through evaporation and crystallization. The hydrogen is discharged through the hydrogen outlet of the chlor-alkali electrolyzer.

[0027] Furthermore, the initially purified hydrogen and a small amount of water enter a hydrogen purification cooling unit for further purification until the hydrogen content is ≥99.99%.

[0028] Compared with the prior art, the present invention has the following advantages: the electrolytic water coupled low-temperature distillation integrated system uses the alkali solution that needs to be cooled to heat the seawater in a negative pressure environment. While the alkali solution is cooled, the heat emitted by the alkali solution during cooling is also utilized. The fresh water generated by the seawater desalination unit is used as the electrolytic water raw material to supplement the alkaline electrolytic cell unit, alleviating the dependence on fresh water resources. The concentrated seawater generated by the electrolytic water coupled low-temperature distillation integrated system directly extracts salts and prepares NaOH, chlorine, and hydrogen through a chlor-alkali electrolytic cell, making the utilization rate of seawater higher. The device is set at sea or by the sea, and the overall footprint is small, realizing the efficient resource utilization of seawater. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 This is a system schematic diagram of Example 1 of the present invention.

[0031] Figure 2 This is a system schematic diagram of Example 2 of the present invention.

[0032] Figure 3 It is a schematic diagram of the overall structure of the alkaline electrolytic cell of the present invention.

[0033] Figure 4 It is a side view of the overall structure of the alkaline electrolytic cell of the present invention.

[0034] Figure 5 Schematic diagram of the bipolar plate structure of the present invention.

[0035] Figure 6 This is a front view of the bipolar plate of the present invention.

[0036] Figure 7 For the present invention Figure 6 AA cross-section of the bipolar plate.

[0037] Figure 8 It is a side view of the bipolar plate of the present invention.

[0038] Fig. 9 It is a schematic diagram of the end plate structure of the present invention.

[0039] Fig.10 It is the front view of the end plate of the present invention.

[0040] Fig.11 For the present invention Fig.10 AA section of the end plate.

[0041] Fig.12 It is a side view of the end plate of the present invention.

[0042] Fig.13 Schematic diagram of the bipolar plate gasket of the present invention.

[0043] Fig.14 It is a schematic diagram of the end plate gasket of the present invention.

[0044] In the figure: 1. alkali solution inlet; 2. gas outlet; 3. sealing groove; 4. mastoid; 5. positioning hole; 6. fastening hole; 7. support column; 8. upper gasket; 9. lower gasket. DETAILED DESCRIPTION

[0045] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0048] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0049] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0050] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0051] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0052] like Figure 1 , Figure 2 As shown, the embodiment of the present invention discloses a hybrid hydrogen production system based on seawater electrolysis and salt electrolysis, including: an electrolysis water coupled low-temperature distillation integrated system, a concentrated seawater processing unit and a hydrogen purification unit, the electrolysis water coupled low-temperature distillation integrated system includes an alkaline electrolyzer unit, an oxygen separation cooling unit, a hydrogen separation cooling unit, an alkali solution circulation filtration unit and a seawater desalination unit, the electrolysis water coupled low-temperature distillation integrated system collects seawater to be treated, the seawater desalination unit is used to heat the seawater, steam removes impurities and condenses to produce fresh water and concentrated seawater to be collected; the ... The outlet is connected to the alkaline electrolytic cell unit. The fresh water in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current. The hydrogen and alkali liquid enter the hydrogen separation cooling unit, and the oxygen and alkali liquid enter the oxygen separation cooling unit. The alkali liquid circulation filtration unit is used to complete the forced circulation of alkali liquid in the alkaline electrolytic cell unit, the hydrogen separation cooling unit, and the oxygen separation cooling unit. The product of the seawater desalination unit includes concentrated seawater, which is directly introduced into the concentrated seawater treatment unit. The concentrated seawater treatment unit is used to purify the concentrated seawater. The purified concentrated seawater is used to prepare NaOH solution, chlorine and hydrogen through the chlor-alkali industry.

[0053] Furthermore, it also includes a hydrogen purification cooling unit, which is arranged inside the water electrolysis coupled low-temperature distillation integrated system or outside the water electrolysis coupled low-temperature distillation integrated system, and is used to purify the hydrogen; when it is arranged inside the water electrolysis coupled low-temperature distillation integrated system, its input end is connected to the hydrogen separation cooling unit; when it is arranged outside the water electrolysis coupled low-temperature distillation integrated system, its input end is respectively connected to the hydrogen separation cooling unit and the hydrogen outlet of the concentrated seawater treatment unit.

[0054] Furthermore, the concentrated seawater treatment unit includes a crystallization purification unit, a refined brine configuration unit, a chlor-alkali electrolytic cell and a drying unit. The crystallization purification unit is connected to an electrolytic water coupled low-temperature distillation integrated system, and is used to complete the crystallization purification of concentrated seawater by evaporation. The refined brine configuration unit is connected to the crystallization purification unit, and the crystallization purification unit is also connected to the fresh water outlet of the electrolytic water coupled low-temperature distillation integrated system, and refined brine is prepared by outputting fresh water and crystallized salt in a preset proportion. The output end of the refined brine configuration unit is connected to a chlor-alkali electrolytic cell, and the chlor-alkali electrolytic cell is used to prepare NaOH solution, chlorine and hydrogen. The drying unit is arranged at the chlorine outlet of the chlor-alkali electrolytic cell, and is used to dry the wet chlorine. The NaOH solution is discharged through the NaOH solution outlet of the chlor-alkali electrolytic cell, and NaOH is prepared by evaporation and crystallization. Hydrogen is discharged through the hydrogen outlet of the chlor-alkali electrolytic cell.

[0055] Furthermore, the seawater enters a seawater desalination unit or a hydrogen separation cooling unit or an oxygen separation cooling unit.

[0056] Furthermore, the hydrogen outlet of the alkaline electrolyzer module is connected to the hydrogen separation cooling unit, the oxygen outlet of the alkaline electrolyzer module is connected to the oxygen separation cooling unit, the alkali liquid inlet of the alkaline electrolyzer module is connected to the seawater desalination unit, the oxygen separation cooling unit separates oxygen and alkali liquid by a gas-liquid separation method, the hydrogen separation cooling unit separates hydrogen and alkali liquid by a gas-liquid separation method, the hydrogen outlet of the hydrogen separation cooling unit is connected to the hydrogen purification cooling unit, the alkali liquid outlet of the oxygen separation cooling unit and the alkali liquid outlet of the hydrogen separation cooling unit are both connected to the alkali liquid circulation filtration unit to provide high-temperature alkali liquid to be cooled, and the fresh water outlet of the seawater desalination unit is connected to the hydrogen separation cooling unit; the device arranged outside the electrolysis water coupled low-temperature distillation integrated system is specifically the rear end of the chlor-alkali electrolyzer.

[0057] Furthermore, the seawater desalination unit includes a device cylinder, a vacuum system, a condenser, a water receiving plate, and a wire mesh separator. The device cylinder is provided with a vacuum system connection port, a seawater inlet port, a concentrated seawater outlet port, a fresh water outlet, and an alkali solution circulation pipe. The device cylinder is connected to the vacuum system through the vacuum system connection port, and is directly connected to seawater or an oxygen separation cooling unit / hydrogen separation cooling unit through the seawater inlet port. The concentrated seawater outlet port is used to collect concentrated seawater. The alkali solution circulation pipe is used to exchange heat between high-temperature alkali solution and seawater, reduce the temperature of the alkali solution, and make the seawater reach the evaporation temperature and evaporate into water vapor. The water vapor is condensed by the condenser. The water receiving plate is used to receive condensed water droplets, and its output end is connected to the fresh water outlet. A wire mesh separator is arranged in the device cylinder, which is used to separate larger droplets and impurities in the water vapor.

[0058] like Figures 3 to 14 As shown, the alkaline electrolytic cell used in the embodiment of the present invention specifically includes a cathode end plate and an anode end plate, and at least one electrolytic cell unit composed of a bipolar plate is arranged between the cathode end plate and the anode end plate; the cathode end plate, the bipolar plate and the anode end plate all include a plate body, and positioning holes 5, fastening holes 6, an alkali solution inlet 1, a gas outlet 2 (i.e., an alkali solution and hydrogen outlet or an alkali solution and oxygen outlet) and a guide component are arranged at corresponding positions of each plate; the guide components of the cathode end plate and the anode end plate are opened on the inner side close to the bipolar plate, and a flow channel for connecting the alkali solution inlet and the gas outlet is opened in the middle position of the end surface of the plate body, and the guide component divides the flow channel in a preset form, and the guide component specifically includes a blocking mechanism and a guide mechanism, and the guide mechanism is arranged on the alkali solution inlet side and the gas outlet side, and the blocking mechanism is a plurality of array-distributed nipples 4, including a central nipple and an annularly distributed nipple with the central nipple as the center and arranged in its circumference at a preset interval.

[0059] Furthermore, the cathode end plate, the bipolar plate and the anode end plate are divided into a plate body and a plate frame by a sealing groove 3. The plate body is arranged inside the plate frame. There are multiple groups of sealing grooves arranged in a circumferential direction. The sealing grooves protrude from the plate body and the plate frame by a preset distance. A plurality of positioning holes are opened on the plate body, and a plurality of mounting holes are opened on the plate frame along its circumference.

[0060] Furthermore, the flow guiding mechanism is a plurality of partition plates arranged at intervals perpendicular to the alkali solution inlet and the gas outlet. By arranging the partition plates, the fluid is evenly dispersed to enter / flow out of the flow channel between the mastoids.

[0061] Furthermore, grooves for installing the upper gasket 8 and the lower gasket 9 are provided on the end surfaces of the alkali solution inlet and the gas outlet, and the shapes of the grooves match the gaskets.

[0062] Furthermore, a support column 7 is provided at the bottom of the frame of the preset plate.

[0063] A method for producing hydrogen by hybrid electrolysis of seawater and salt, comprising the following steps:

[0064] The water electrolysis coupled cryogenic distillation integrated system is connected to the seawater source to start the hybrid hydrogen production of seawater electrolysis and salt electrolysis, among which,

[0065] The seawater is directly transported to the desalination unit for fresh water production and concentrated seawater separation, or enters the desalination unit after passing through the oxygen separation cooling unit and the hydrogen separation cooling unit. The seawater can play an auxiliary cooling role in the oxygen separation cooling unit and the hydrogen separation cooling unit.

[0066] Fresh water in the alkaline electrolyser unit is decomposed into hydrogen and oxygen by direct current;

[0067] The oxygen outlet of the alkaline electrolyzer unit transports oxygen and alkaline solution to the oxygen separation cooling unit for gas-liquid separation;

[0068] The hydrogen outlet of the alkaline electrolyzer unit transports hydrogen and alkaline solution to the hydrogen separation cooling unit for gas-liquid separation;

[0069] The alkali liquid circulation filtration unit extracts the alkali liquid from the oxygen separation cooling unit and the hydrogen separation cooling unit, cools it in the seawater desalination unit, and finally transports it to the alkaline electrolyzer unit to complete the cooling and forced circulation of the alkali liquid;

[0070] The heat emitted by the alkali solution during cooling in the seawater desalination unit is used to heat the seawater under negative pressure to produce fresh water. The produced fresh water is transported to the hydrogen separation cooling unit to supplement the raw fresh water used for electrolysis, and also assists in hydrogen scrubbing and cooling.

[0071] The crystallization purification of concentrated seawater is completed by evaporation through the crystallization purification unit. The refined brine configuration unit prepares refined brine through a preset ratio of fresh water and crystal salt. The refined brine is transported to the chlor-alkali electrolyzer to prepare NaOH solution, chlorine and hydrogen. The wet chlorine is dried by the drying unit. The NaOH solution discharged from the NaOH solution outlet of the chlor-alkali electrolyzer is used to prepare NaOH through evaporation and crystallization. The hydrogen is discharged through the hydrogen outlet of the chlor-alkali electrolyzer.

[0072] Furthermore, the initially purified hydrogen and a small amount of water enter a hydrogen purification cooling unit for further purification until the hydrogen content is ≥99.99%.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydrogen production system based on seawater electrolysis and salt electrolysis, characterized in that: include: An electrolytic water coupled low-temperature distillation integrated system, a concentrated seawater treatment unit and a hydrogen purification unit. The electrolytic water coupled low-temperature distillation integrated system comprises an alkaline electrolyzer unit, an oxygen separation cooling unit, a hydrogen separation cooling unit, an alkali solution circulation filtration unit and a seawater desalination unit. The seawater to be treated is collected in the electrolytic water coupled low-temperature distillation integrated system. The seawater desalination unit is used to heat the seawater, remove impurities with steam and condense to produce fresh water and concentrated seawater to be collected; the output end of the seawater desalination unit is connected to the alkaline electrolyzer unit, the fresh water in the alkaline electrolyzer unit is decomposed into hydrogen and oxygen under the action of direct current, the hydrogen and alkali solution enter the hydrogen separation cooling unit, and the oxygen and alkali solution enter the oxygen separation cooling unit; the alkali solution circulation filtration unit is used to complete the forced circulation of alkali solution in the alkaline electrolyzer unit, the hydrogen separation cooling unit and the oxygen separation cooling unit; the product of the seawater desalination unit comprises concentrated seawater, which is directly introduced into the concentrated seawater treatment unit; the concentrated seawater treatment unit is used to purify the concentrated seawater, and the purified concentrated seawater is used to prepare NaOH solution, chlorine and hydrogen through the chlor-alkali industry.

2. The hybrid hydrogen production system based on seawater electrolysis and salt electrolysis according to claim 1 is characterized in that: It also includes a hydrogen purification cooling unit, which is arranged inside the water electrolysis coupled low-temperature distillation integrated system or outside the water electrolysis coupled low-temperature distillation integrated system, and is used to purify the hydrogen; when it is arranged inside the water electrolysis coupled low-temperature distillation integrated system, its input end is connected to the hydrogen separation cooling unit; when it is arranged outside the water electrolysis coupled low-temperature distillation integrated system, its input end is respectively connected to the hydrogen separation cooling unit and the hydrogen outlet of the concentrated seawater treatment unit; the unit arranged outside the water electrolysis coupled low-temperature distillation integrated system is specifically the rear end of the chlor-alkali electrolyzer.

3. The hybrid hydrogen production system based on seawater electrolysis and salt electrolysis according to claim 1 is characterized in that: The concentrated seawater treatment unit includes a crystallization purification unit, a refined brine configuration unit, a chlor-alkali electrolytic cell and a drying unit. The crystallization purification unit is connected to an electrolytic water coupled low-temperature distillation integrated system, and is used to complete the crystallization purification of concentrated seawater by evaporation. The refined brine configuration unit is connected to the crystallization purification unit, and the crystallization purification unit is also connected to the fresh water outlet of the electrolytic water coupled low-temperature distillation integrated system, and refined brine is prepared by outputting fresh water and crystallized salt in a preset proportion. The output end of the refined brine configuration unit is connected to a chlor-alkali electrolytic cell, and the chlor-alkali electrolytic cell is used to prepare NaOH solution, chlorine and hydrogen. The drying unit is arranged at the chlorine outlet of the chlor-alkali electrolytic cell, and is used to dry wet chlorine. The NaOH solution is discharged through the NaOH solution outlet of the chlor-alkali electrolytic cell, and NaOH is prepared by evaporation and crystallization. Hydrogen is discharged through the hydrogen outlet of the chlor-alkali electrolytic cell.

4. The hybrid hydrogen production system based on seawater electrolysis and salt electrolysis according to claim 1 is characterized in that: The seawater enters the seawater desalination unit or the hydrogen separation cooling unit or the oxygen separation cooling unit.

5. The hybrid hydrogen production system based on seawater electrolysis and salt electrolysis according to claim 1 is characterized in that: The hydrogen outlet of the alkaline electrolyzer module is connected to the hydrogen separation cooling unit, the oxygen outlet of the alkaline electrolyzer module is connected to the oxygen separation cooling unit, the alkali liquid inlet of the alkaline electrolyzer module is connected to the seawater desalination unit, the oxygen separation cooling unit separates oxygen and alkali liquid by a gas-liquid separation method, the hydrogen separation cooling unit separates hydrogen and alkali liquid by a gas-liquid separation method, the hydrogen outlet of the hydrogen separation cooling unit is connected to the hydrogen purification cooling unit, the alkali liquid outlet of the oxygen separation cooling unit and the alkali liquid outlet of the hydrogen separation cooling unit are both connected to the alkali liquid circulation filtration unit to provide high-temperature alkali liquid to be cooled, and the fresh water outlet of the seawater desalination unit is connected to the hydrogen separation cooling unit.

6. The hybrid hydrogen production system based on seawater electrolysis and salt electrolysis according to claim 1 is characterized in that: The desalination unit comprises a device cylinder, a vacuum system, a condenser, a water receiving plate, and a wire mesh separator. The device cylinder is provided with a vacuum system connection port, a seawater inlet port, a concentrated seawater outlet port, a fresh water outlet port, and an alkali solution circulation pipe. The device cylinder is connected to the vacuum system through the vacuum system connection port, and is directly connected to seawater or an oxygen separation cooling unit / hydrogen separation cooling unit through the seawater inlet port. The concentrated seawater outlet port is used to collect concentrated seawater. The alkali solution circulation pipe is used to exchange heat between high-temperature alkali solution and seawater, reduce the temperature of the alkali solution, and make the seawater reach the evaporation temperature and evaporate into water vapor. The water vapor is condensed by the condenser. The water receiving plate is used to receive condensed water droplets, and its output end is connected to the fresh water outlet. A wire mesh separator is arranged in the device cylinder, which is used to separate larger droplets and impurities in the water vapor.

7. The hybrid hydrogen production system based on seawater electrolysis and salt electrolysis according to claim 1 is characterized in that: An alkaline electrolytic cell specifically comprises a cathode end plate and an anode end plate, between which at least one electrolytic cell unit consisting of a bipolar plate is arranged; the flow guide components of the cathode end plate and the anode end plate are opened on the inner side close to the bipolar plate, and a flow channel for connecting an alkali solution inlet and a gas outlet is opened in the middle position of the end surface of the plate body, and the flow channel is divided into a preset form by the flow guide component, and the flow guide component specifically comprises a blocking mechanism and a flow guide mechanism, and the flow guide mechanism is arranged on the alkali solution inlet side and the gas outlet side, and the blocking mechanism is a plurality of array-distributed nipples, including a central nipple and annularly distributed nipples arranged in a preset spacing in the circumference of the central nipple with the central nipple as the center.

8. The hybrid hydrogen production system based on seawater electrolysis and salt electrolysis according to claim 7 is characterized in that: The flow guiding mechanism is a plurality of partition plates arranged perpendicularly to the alkali solution inlet and the gas outlet. By arranging the partition plates, the fluid is evenly dispersed to enter / flow out of the flow channel between the mastoids.

9. A method for producing hydrogen by hybrid electrolysis of seawater and salt electrolysis according to any one of claims 1 to 8, characterized in that: The steps include: The water electrolysis coupled cryogenic distillation integrated system is connected to the seawater source to start the hybrid hydrogen production of seawater electrolysis and salt electrolysis, among which, The seawater is directly transported to the desalination unit for fresh water production and concentrated seawater separation, or enters the desalination unit after passing through the oxygen separation cooling unit and the hydrogen separation cooling unit. The seawater can play an auxiliary cooling role in the oxygen separation cooling unit and the hydrogen separation cooling unit. Fresh water in the alkaline electrolyser unit is decomposed into hydrogen and oxygen by direct current; The oxygen outlet of the alkaline electrolyzer unit transports oxygen and alkaline solution to the oxygen separation cooling unit for gas-liquid separation; The hydrogen outlet of the alkaline electrolyzer unit transports hydrogen and alkaline solution to the hydrogen separation cooling unit for gas-liquid separation; The alkali liquid circulation filtration unit extracts the alkali liquid from the oxygen separation cooling unit and the hydrogen separation cooling unit, cools it in the seawater desalination unit, and finally transports it to the alkaline electrolyzer unit to complete the cooling and forced circulation of the alkali liquid; The heat emitted by the alkali solution during cooling in the seawater desalination unit is used to heat the seawater under negative pressure to produce fresh water, which is then transported to the hydrogen separation cooling unit to supplement the raw fresh water used for electrolysis and also assist in hydrogen scrubbing and cooling. The crystallization purification of concentrated seawater is completed by evaporation through the crystallization purification unit. The refined brine configuration unit prepares refined brine through a preset ratio of fresh water and crystal salt. The refined brine is transported to the chlor-alkali electrolyzer to prepare NaOH solution, chlorine and hydrogen. The wet chlorine is dried by the drying unit. The NaOH solution discharged from the NaOH solution outlet of the chlor-alkali electrolyzer is used to prepare NaOH through evaporation and crystallization. The hydrogen is discharged through the hydrogen outlet of the chlor-alkali electrolyzer.

10. The method according to claim 9, characterized in that The initially purified hydrogen and a small amount of water enter the hydrogen purification cooling unit for further purification until the hydrogen content is ≥99.99%.

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