Bipolar plate combination structure of high-pressure caustic lye electrolytic cell and method for improving electrolysis efficiency

Abstract

This invention relates to a bipolar plate assembly structure for a high-pressure alkaline electrolyzer and a method for improving electrolysis efficiency. The bipolar plate assembly structure includes a bipolar plate body, insulating components, a hard seal, a soft seal, and a diaphragm. The bipolar plate body consists of an electrode frame and a main electrode plate. The main electrode plate has hydrogen-side channel holes, oxygen-side channel holes, and alkaline channel holes. Insulating components are provided at the hydrogen-side channel holes, oxygen-side channel holes, and alkaline channel holes. A hard seal, a soft seal, and a diaphragm are provided between adjacent bipolar plate bodies. Compared with the prior art, this invention reduces the weight of a single electrode plate in the water electrolyzer by moving the fluid channel from the electrode frame to the main electrode plate area, eliminating the openings in the electrode frame flow channels, increasing the strength of the electrode frame, and supplementing it with an insulating seal design. This reduces the influence of stray current and improves electrolysis efficiency.

Description

Technical Field

[0001] This invention relates to the field of alkaline water electrolysis hydrogen production equipment, and in particular to a bipolar plate combination structure for a high-pressure alkaline electrolyzer and a method for improving electrolysis efficiency. Background Technology

[0002] The mainstream high-pressure alkaline electrolyzers currently on the market are bipolar pressure filter structures. Their core component, the bipolar plate, is composed of a main plate and an electrode frame welded together. The electrode frame is located outside the main plate. The upper part of the electrode frame has two sets of gas-liquid channel holes, corresponding to the oxygen-alkali mixture and hydrogen-alkali mixture generated during electrolysis, respectively. The lower part of the electrode frame has alkaline solution through holes. Adjacent bipolar plates sequentially clamp the cathode electrode, diaphragm, and anode electrode in a top-to-top configuration within the main plate area. A sealing gasket is placed between the electrode frame areas. The outermost part of the electrode frame has a serrated sealing line area, and the remaining area is the overlapping area of ​​the diaphragm and sealing gasket. (See...) Figure 1 Currently, the fluid flow channels in mainstream high-pressure alkaline electrolyzers on the market are all made by opening holes in the electrode frame. This method has the following problems:

[0003] (1) A large number of round holes and waist-shaped holes on the pole frame will increase the overall machining difficulty and cause the total cost to rise.

[0004] (2) All electrode frames on the market are made of nickel-plated carbon steel. In actual operation, the fluid channels on the electrode frame are subject to fluid erosion, which poses a high risk of corrosion. At the same time, due to the complex processing and numerous openings, if local quality problems occur during the electroplating process, the carbon steel substrate of the electrode frame will be corroded by high-temperature alkaline solutions.

[0005] (3) More openings will increase the deformation of the electrode frame, which will increase the overall assembly difficulty of the electrolytic cell.

[0006] (4) When a larger cross-sectional area of ​​the main channel is required for a high-hydrogen-yield electrolyzer, it can only be implemented by increasing the width of the electrode frame or by increasing the number of main channels, but this will further increase the weight of the electrode plate or make the structure of the electrode plate more fragile.

[0007] (5) The main channel is set on the electrode frame of the electrode plate. The shortest distance between two adjacent electrode plates on the main channel hole is only 2-3 mm (the thickness of the sealing gasket). Due to the good conductivity of strong alkaline solution, a certain amount of stray current will exist in the main channel hole area during the actual operation of the electrolytic cell, which will affect the overall electrolysis efficiency.

[0008] (6) The flow pattern of the alkaline solution in each electrolysis cell is restricted and unevenly distributed, which can easily lead to dry spots in local areas.

[0009] (7) Because the alkaline solution is unevenly distributed, the gas produced by electrolysis tends to accumulate at higher points. The gas content in this area is relatively high, which leads to an increase in the electrolyte resistance and reduces the electrolysis efficiency. Summary of the Invention

[0010] The purpose of this invention is to overcome the defects of the prior art by providing a bipolar plate combination structure for a high-pressure alkaline electrolyzer and a method for improving electrolysis efficiency.

[0011] The objective of this invention can be achieved through the following technical solution: a bipolar plate assembly structure for a high-pressure alkaline electrolyzer, comprising a bipolar plate body, an insulating component, a hard seal, a soft seal, and a diaphragm;

[0012] The bipolar plate body consists of two parts: an electrode frame and a main electrode plate. The main electrode plate is provided with hydrogen-side channel holes, oxygen-side channel holes and alkali solution channel holes. Insulating components are provided at the hydrogen-side channel holes, oxygen-side channel holes and alkali solution channel holes. Hard seal, soft seal and diaphragm are provided between two adjacent bipolar plate bodies.

[0013] Preferably, the hydrogen-side channel, oxygen-side channel, and alkali channel can be circular, elliptical, triangular with rounded corners, rectangular, or other similar shapes.

[0014] Preferably, the insulating components at the hydrogen-side channel hole, oxygen-side channel hole, and alkali solution channel hole are respectively provided with holes that are similar in shape to the hydrogen-side channel hole, oxygen-side channel hole, and alkali solution channel hole but smaller in size.

[0015] The present invention uses an insulating component to cover the main channels (hydrogen-side channel hole, oxygen-side channel hole and alkali solution channel hole) on the main electrode plate. The insulating component has holes at the main channel positions of the main electrode plate to form the main fluid channel.

[0016] Preferably, the insulating component is made of special engineering plastics that are resistant to high temperature and strong alkaline environments. The material form can be PPS, PSU, PEEK or composite modified special engineering plastics based on these materials.

[0017] Preferably, the insulating assembly includes a front insulating plate and a back insulating plate;

[0018] The front insulating plate and the back insulating plate are respectively disposed on both sides of the main electrode plate, and a sealing ring is provided at the channel hole.

[0019] More preferably, the front insulating plate and the back insulating plate are provided with flow channel grooves. For the front insulating plate at the hydrogen-side channel hole and the oxygen-side channel hole, the flow channel grooves will guide the fluid in the chamber to flow only into the hydrogen-side channel hole. For the back insulating plate at the hydrogen-side channel hole and the oxygen-side channel hole, the flow channel grooves will guide the fluid in the chamber to flow only into the oxygen-side channel hole.

[0020] More preferably, the front insulating plate and the back insulating plate are provided with sealing grooves for installing the sealing ring.

[0021] More preferably, the sealing ring is made of rubber material that is resistant to high temperature and strong alkaline environment. The material can be FKM fluororubber of a special grade, and the cross-sectional shape can be O-type or T-type.

[0022] Preferably, the insulating component is provided with branch channels.

[0023] Preferably, the hard seal has an annular structure and covers the pole frame area.

[0024] Preferably, the soft seal covers the area of ​​the insulating component, and the soft seal has holes corresponding to the hydrogen-side channel hole, the oxygen-side channel hole, and the alkali solution channel hole.

[0025] More preferably, the soft sealing material can be a sealing material that is resistant to high temperature and strong alkaline environment, and the optional form is expanded polytetrafluoroethylene.

[0026] Preferably, the diaphragm has holes corresponding to the hydrogen-side channel holes, oxygen-side channel holes, and alkali solution channel holes.

[0027] Preferably, the main electrode plate has hydrogen-side channel holes and oxygen-side channel holes on the upper side and alkali solution channel holes on the lower side.

[0028] Preferably, the bipolar plate body has a circular structure and is formed by welding the electrode frame and the main electrode plate together.

[0029] A method for improving the electrolysis efficiency of a high-pressure alkaline electrolyzer is carried out using the above-mentioned bipolar plate combination structure.

[0030] Preferably, the alkaline solution enters the electrolytic cell through the lower alkaline solution main channel, and is dispersed into the cathode and anode sides of the electrolysis chamber through the alkaline solution flow channel on the lower insulating component. Under the action of the electrolysis current, a mixture of hydrogen and alkaline solution is generated on the cathode side and collected in the hydrogen-side main channel through the flow channel groove of the upper insulating component; a mixture of oxygen and alkaline solution is generated on the anode side and collected in the oxygen-side main channel through the flow channel groove of the upper insulating component.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. This invention reduces the weight of a single electrode plate in a water electrolyzer by moving the fluid channel from the electrode frame to the main electrode plate area, eliminating the openings in the electrode frame flow channel, increasing the strength of the electrode frame, and supplementing it with an insulating and sealing design, thereby reducing the influence of stray current and improving electrolysis efficiency.

[0033] 2. By moving the main fluid channel from the electrode frame area to the main electrode plate area, this invention significantly reduces the width of the electrode frame compared to the traditional alkaline electrolytic cell electrode frame, thereby reducing the machining difficulty and processing time of the electrode frame;

[0034] 3. Due to the greatly simplified design of the electrode frame, the fluid channel opening design is eliminated, avoiding nickel plating quality defects inside the hole and improving the safety of the electrode frame;

[0035] 4. This invention simplifies the electrode frame design through a special structural design, which not only reduces the influence of stray current during the electrolysis process, thereby improving the electrolysis efficiency of the electrolytic cell, but also reduces the number of openings in the electrode frame and increases the strength of the electrode frame.

[0036] 5. The present invention significantly increases the resistance of alkaline solution conduction between different chambers through the main channel by using branch channels on the insulating components, thereby greatly reducing the loss of stray current and improving the overall electrolysis efficiency of the electrolytic cell.

[0037] 6. The present invention, through the flow channel design on the insulating component, enables the alkaline solution to be distributed more evenly in the electrolysis chamber, avoiding the generation of dry spots in local areas;

[0038] 7. Through the structure and flow channel design of the upper insulating component, the present invention can fully collect the gas formed during the electrolysis process, avoid the accumulation of gas in local areas, reduce the resistance of the electrolyte due to local gas content, and improve the electrolysis efficiency. Attached Figure Description

[0039] Figure 1 This is the basic structural form of the traditional polar frame;

[0040] Figure 2 This is an exploded view of the bipolar plate assembly structure of the present invention;

[0041] Figure 3 This is a front view of the bipolar plate assembly structure of the present invention;

[0042] Figure 4 This is a partially enlarged view of the bipolar plate assembly structure of Embodiment 3 of the present invention;

[0043] Figure 5 for Figure 4 Sectional view of plane AA;

[0044] Figure 6 for Figure 4 BB section view;

[0045] Figure 7 This is a partial cross-sectional view of the bipolar plate assembly structure of Embodiment 4 of the present invention. Figure 1 ;

[0046] Figure 8This is a partial cross-sectional view of the bipolar plate assembly structure of Embodiment 4 of the present invention. Figure 2 ;

[0047] In the diagram: 1-Bipolar plate body, 11-Electrical frame, 12-Main electrode plate, 121-Hydrogen side channel hole, 122-Oxygen side channel hole, 123-Alkali solution channel hole, 2-Insulation component, 21-Front insulation plate, 22-Back insulation plate, 3-Hard seal, 4-Soft seal, 5-Diaphragm, 6-Sealing ring, 7-Flow channel groove, 8-Branch channel, a-Hydrogen side flow channel, b-Oxygen side flow channel, c-Alkali solution flow channel. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0049] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0050] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0051] Example 1

[0052] A bipolar plate assembly structure for a high-pressure alkaline electrolyzer, such as... Figures 2-3 As shown, it includes a bipolar plate body 1, an insulation component 2, a hard seal 3, a soft seal 4, and a diaphragm 5.

[0053] The bipolar plate body 1 is composed of two parts: the electrode frame 11 and the main electrode plate 12. The hydrogen side channel hole 121, the oxygen side channel hole 122 and the alkali solution channel hole 123 are provided on the main electrode plate 12, and an insulating component 2 is provided at each channel hole. A hard seal 3, a soft seal 4 and a diaphragm 5 are provided between two adjacent bipolar plate bodies 1.

[0054] This embodiment significantly reduces the width of the electrode frame by moving the main fluid channel from the electrode frame area to the main electrode plate area, compared with the traditional alkaline electrolytic cell electrode frame, thus reducing the machining difficulty and processing time of the electrode frame.

[0055] Example 2

[0056] A bipolar plate assembly structure for a high-pressure alkaline electrolyzer includes a bipolar plate body 1, an insulating component 2, a hard seal 3, a soft seal 4, and a diaphragm 5.

[0057] in:

[0058] The bipolar plate body 1 is still composed of two parts, the electrode frame 11 and the main electrode plate 12, which are welded together. Two independent holes are opened in the upper part of the main electrode plate 12, avoiding the weld seam, corresponding to the main channels on the hydrogen side and the oxygen side, respectively. One or two holes are opened in the lower part of the main electrode plate 12, avoiding the weld seam, corresponding to the main channel of the alkali solution. The bipolar plate body 1 is still made of carbon steel with electroplating, which enables the bipolar plate to work in a high temperature and strong alkali environment.

[0059] The insulating assembly 2 consists of an independent upper insulating assembly and a lower insulating assembly. The upper insulating assembly covers the hydrogen and oxygen side main channels of the main electrode plate, while the lower insulating assembly covers the alkali solution main channel of the main electrode plate. The insulating assembly 2 has holes of similar shape but slightly smaller size at the main channel openings on the main electrode plate to allow fluid within the main channel to pass through. The main fluid channel is formed by the stacking of multiple insulating assemblies. The slightly smaller hole design provides sufficient installation space for the sealing ring 6 and, through the action of the insulating assembly 2 and the sealing ring 6, prevents the fluid in the main channel from directly contacting the main electrode plate. Each part of the insulating assembly 2 is composed of two insulating plates, one on each side, which are attached to the main electrode plate 12. The front and back insulating plates are provided with flow channel grooves 7 and sealing grooves on both sides. For the front insulating plate 21 of the upper insulating assembly, its flow channel grooves 7 will guide the fluid in the chamber to flow only into the hydrogen side main channel. Similarly, for the back insulating plate 22, its flow channel grooves 7 will guide the fluid in the chamber to flow only into the oxygen side main channel.

[0060] The sealing ring 6 is located between the two insulating plates on the insulating assembly. Since the two insulating plates are separate structures with a gap between them, without the sealing ring 6, the gas generated in the electrolysis chamber would directly enter the main channel on the hydrogen or oxygen side, forming a hydrogen-oxygen mixture. Therefore, the sealing ring 6 is necessary to prevent this. The sealing ring 6 is designed with sealing grooves on the insulating plates, allowing it to be installed in a fixed groove and preventing it from being dislodged and losing its sealing function due to the pressure difference between the two sides of the seal.

[0061] The hard seal 3 is located between two adjacent combined bipolar plates, covering the area of ​​the bipolar plate frame 12. The area covering the water line of the frame 12 serves to seal the electrolytic cell to the outside, and the area covering the diaphragm on the frame 12 serves to fix the diaphragm 5.

[0062] The soft seal 4 is located between two adjacent combined bipolar plates, covering the area of ​​the insulating component 2 of the bipolar plates. It serves to isolate and seal the electrolytic cell chamber from the main channel area, and to seal the hydrogen-side main channel from the oxygen-side main channel. For the openings in the insulating component 2 created by the main channel, the soft seal also needs to have openings to allow fluid passage. Since the pressure difference between the hydrogen and oxygen chambers is strictly controlled during electrolytic cell operation, the soft seal 4, compared to the hard seal 3, does not need to bear a large pressure difference, thus reducing the specific pressure requirement of the soft seal. The soft seal 4 consists of independent upper and lower soft seals, with the upper soft seal corresponding to the upper insulating component and the lower soft seal corresponding to the lower insulating component.

[0063] The diaphragm 5 is located between two adjacent combined bipolar plates, separating the cavity between the two main plates 12 to form a hydrogen-side chamber and an oxygen-side chamber. Unlike traditional electrolyzers, the diaphragm 5 in this embodiment needs to have openings in the main channel area of ​​the insulating component to allow fluid to pass through.

[0064] In summary, the alkali solution enters the electrolytic cell through the lower main alkali solution channel and is dispersed into the cathode and anode sides of the electrolysis chambers through the alkali solution flow channels on the lower insulating component. Under the action of the electrolytic current, a mixture of hydrogen and alkali solution is generated on the cathode side and collected in the hydrogen-side main channel through the flow channel grooves of the upper insulating component; a mixture of oxygen and alkali solution is generated on the anode side and collected in the oxygen-side main channel through the flow channel grooves of the upper insulating component. Through the combined action of soft seals and sealing rings, each electrolysis chamber is sealed and isolated from the hydrogen / oxygen-side main channel and the alkali solution main channel, preventing the mixing of hydrogen and oxygen.

[0065] Example 3

[0066] A bipolar plate assembly structure for a high-pressure alkaline electrolyzer is disclosed. The bipolar plates are generally circular and are welded together from an electrode frame and a main electrode plate. A window is formed in the lower region of the main electrode plate corresponding to the main alkaline channel, and two windows are formed in the upper region corresponding to the hydrogen-side main channel and the oxygen-side main channel, respectively. Figures 5-6 As shown, the upper insulating assembly consists of two insulating plates, a front one and a back one, which are covered by O-rings 6 in the flow channel area. The lower insulating assembly also consists of two insulating plates, a front one and a back one, which are covered by O-rings 6 in the flow channel area. A soft seal 4 is filled between the insulating assemblies on adjacent plates. This combined structure separates the main flow channel fluid from the fluid in the chamber. The alkali solution can only enter the chamber cathode from the main channel through the flow channel on the lower insulating assembly, and the produced gas-liquid mixture can only enter the main gas-liquid channel through the flow channel on the upper insulating assembly. Because the insulating assemblies are non-conductive, the equivalent resistance formed by the strong electrolyte alkali solution between adjacent plates will increase significantly, thereby greatly reducing stray current in this area and improving overall electrolysis efficiency.

[0067] Example 4

[0068] A bipolar plate assembly structure for a high-pressure alkaline electrolyzer is disclosed. The bipolar plates are generally circular and are welded together from an electrode frame and a main electrode plate. A window is formed in the lower region of the main electrode plate corresponding to the main alkali solution channel, and two windows are formed in the upper region corresponding to the hydrogen-side main channel and the oxygen-side main channel, respectively. Figures 7-8 As shown, the upper insulating assembly consists of two insulating plates, a front one and a back one, which are covered in the flow channel opening area by a T-shaped sealing ring 6. Similarly, the lower insulating assembly also consists of two insulating plates, a front one and a back one, which are covered in the flow channel opening area by a T-shaped sealing ring 6. A soft seal 4 is filled between the insulating assemblies on adjacent plates. This combined structure separates the main flow channel fluid from the fluid in the chamber. The alkali solution can only enter the chamber cathode from the main channel through the flow channel on the lower insulating assembly, while the produced gas-liquid mixture can only enter the main gas-liquid channel through the flow channel on the upper insulating assembly. Because the insulating assemblies are non-conductive, the equivalent resistance formed by the strong electrolyte alkali solution conducting between adjacent plates will increase significantly, thereby greatly reducing stray current in this area and improving overall electrolysis efficiency.

[0069] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A bipolar plate assembly structure of a high-pressure caustic electrolyzer, characterized by comprising: It includes a bipolar plate body (1), an insulation assembly (2), a hard seal (3), a soft seal (4), and a diaphragm (5); The bipolar plate body (1) is composed of two parts: the pole frame (11) and the main pole plate (12). The main pole plate (12) is provided with hydrogen side channel hole (121), oxygen side channel hole (122) and alkali solution channel hole (123). Insulating components (2) are provided at the hydrogen side channel hole (121), oxygen side channel hole (122) and alkali solution channel hole (123). A hard seal (3), a soft seal (4) and a diaphragm (5) are provided between two adjacent bipolar plate bodies (1). The insulating component (2) includes a front insulating plate (21) and a back insulating plate (22). The front insulating plate (21) and the back insulating plate (22) are respectively disposed on both sides of the main electrode plate (12), and a sealing ring (6) is provided at the channel hole. The front insulating plate (21) and the back insulating plate (22) are provided with flow channel grooves. For the front insulating plate at the hydrogen side channel hole (121) and the oxygen side channel hole (122), its flow channel grooves will guide the fluid in the chamber to flow only into the hydrogen side channel hole (121). For the back insulating plate at the hydrogen side channel hole (121) and the oxygen side channel hole (122), its flow channel grooves will guide the fluid in the chamber to flow only into the oxygen side channel hole (122). The hard seal (3) has a ring structure and covers the area of ​​the pole frame (11); The soft seal (4) covers the area of ​​the insulating component (2), and the soft seal (4) is provided with holes corresponding to the hydrogen side channel hole (121), the oxygen side channel hole (122) and the alkali solution channel hole (123); The bipolar plate body (1) has a circular structure and is formed by welding the pole frame (11) and the main pole plate (12).

2. The bipolar plate assembly of the high-alkaline electrolyzer according to claim 1, wherein The insulating components (2) at the hydrogen-side channel hole (121), oxygen-side channel hole (122) and alkali channel hole (123) are respectively provided with holes that are similar in shape to the hydrogen-side channel hole (121), oxygen-side channel hole (122) and alkali channel hole (123) but smaller in size.

3. The bipolar plate assembly of the high-alkaline electrolyzer of claim 1, wherein The front insulating plate (21) and the back insulating plate (22) are provided with sealing grooves for installing the sealing ring (6).

4. The bipolar plate assembly of the high-alkaline electrolyzer of claim 1, wherein The diaphragm (5) is provided with holes corresponding to the hydrogen-side channel hole (121), the oxygen-side channel hole (122), and the alkali channel hole (123).

5. The bipolar plate assembly of the high-alkaline electrolyzer of claim 1, wherein The main electrode plate (12) is provided with hydrogen-side channel hole (121) and oxygen-side channel hole (122) on the upper side, and with alkali channel hole (123) on the lower side.

6. A method for improving the efficiency of electrolysis in a high pressure caustic soda electrolyzer, characterized by, The bipolar plate combination structure according to any one of claims 1 to 5 is used.

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