Alkaline electrolytic cell with trapezoidal cross section

Abstract

The invention relates to an alkaline electrolytic bath with a trapezoidal section, which comprises an electrolytic bath main body and a plurality of electrolytic units arranged in the electrolytic bath main body, the mastoid plate is fixedly mounted in the middle of the pole frame; the cathode supporting plate is fixed on one side of the mastoid plate; the anode supporting plate is fixed on the other side of the mastoid plate; the cathode plate is fixedly mounted on the cathode supporting plate; the anode plate is fixedly mounted on the anode supporting plate; trapezoidal or triangular or arc-shaped convex edges and grooves with similar section shapes are respectively arranged at the same positions in the middle of two surfaces of the polar frame ring plate, so that a self-positioning structure which is matched in pairs can be realized when two polar plates are assembled. The bending deflection in the middle of the electrolytic cell main body is reduced; the supporting strength of the two ends is improved; the raw material utilization rate of the assembly is improved; the reaction area of the electrolysis chamber unit is increased; and meanwhile, the assembling precision of the electrolytic cell is improved.

Description

Technical Field

[0001] This invention relates to the field of new energy technology for hydrogen production by water electrolysis, specifically to an alkaline electrolyzer with a trapezoidal cross-section. Background Technology

[0002] Hydrogen production is a crucial link in the new energy field, with electrolysis being an important source and direction for green hydrogen. Alkaline electrolyzers are currently the most mature and cost-effective option for electrolytic hydrogen production. Existing alkaline electrolyzers are mostly cylindrical in shape and horizontally placed. The main body is composed of multiple stacked electrolysis chamber units, supported by end plates at both ends, and tightened around the perimeter with screws to form a "simply supported beam" structure. The central cylindrical section is suspended in the air. The electrode frames on the outer side of the main electrode plate of each electrolysis chamber unit are positioned and fixed with pins. High pressure clamping of the central cylindrical section by the end plates ensures the rigidity of the electrolyzer.

[0003] However, large alkaline electrolyzers have a heavy main body, long distance between end plates, numerous components in the middle electrolysis chamber, and are typically suspended horizontally. Although multiple sets of disc springs at both ends of the screw stabilize the pressure and increase displacement reserve to some extent, factors such as the continuous decrease in elasticity due to aging of the gaskets, permanent deformation of the porous diaphragm, and natural creep elongation of the screw under tension reduce the clamping force of the electrolyzer screw. The main body of the electrolyzer is prone to sagging and deformation under the bending moment caused by gravity, and the ends of the main body are prone to sliding under shear stress. The pressure of the anode and cathode plates on the diaphragm can cause the diaphragm to rupture, resulting in cross-contamination and leakage of anode and cathode gases, which severely endangers the safety of the electrolyzer and seriously affects its service life. Furthermore, all parts are circular, requiring the removal of the peripheral edges of the rectangular raw materials during the preparation of the electrolyzer components, resulting in structural waste of raw materials and reducing material utilization. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a trapezoidal cross-section alkaline electrolytic cell.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A trapezoidal cross-section alkaline electrolytic cell includes an electrolytic cell body and multiple electrolytic units disposed within the electrolytic cell body. Each electrolytic unit includes:

[0007] Polar frame;

[0008] The nipple plate is fixedly installed in the middle of the pole frame;

[0009] A cathode support plate is fixed to one side of the nipple plate;

[0010] Anode support plate, fixed on the other side of the nipple plate;

[0011] The cathode plate is fixedly mounted on the cathode support plate;

[0012] The anode plate is fixedly mounted on the anode support plate;

[0013] Sealing gaskets are installed on both sides of the electrode frame to form bipolar plates.

[0014] Furthermore, a diaphragm is provided between adjacent electrolysis units within the main body of the electrolytic cell.

[0015] Furthermore, an insulating plate is provided on the inner wall of the main body of the electrolytic cell.

[0016] Furthermore, the electrolysis units and diaphragms within the main body of the electrolytic cell are arranged sequentially at intervals.

[0017] Furthermore, the electrode frame includes a frame body, with an electrolyte inlet at the bottom of the frame body, a hydrogen outlet and an oxygen outlet at the top of the frame body, and a central cavity in the frame body serving as an intermediate electrolysis chamber.

[0018] Furthermore, the frame is trapezoidal, with rounded corners at all four corners, and the tilt angles of the two sides of the frame are 10° to 45°.

[0019] Furthermore, the frame has a raised ridge on the front edge and a groove on the back edge corresponding to the raised ridge.

[0020] Furthermore, when adjacent electrolysis units are spliced ​​together, the protruding ridges of the frame match the grooves on the adjacent frames, and the diaphragm is located between the adjacent frames.

[0021] Furthermore, the cross-sectional shape of the convex ridge is consistent with the cross-sectional shape of the groove, and the cross-sectional shape of the convex ridge is triangular, trapezoidal, or arc-shaped.

[0022] Furthermore, the height of the ridge is greater than the depth of the groove, and the sealing gasket is installed at the fitting position between the ridge and the groove.

[0023] The beneficial effects of this invention are: 1. It reduces the bending deflection (stiffness) in the middle of the electrolytic cell body:

[0024] The screw centerline and the shape of the electrolytic chamber surrounding the main body of the electrolytic cell are both isosceles trapezoids with two sides at a certain angle. When the electrolytic cell is placed horizontally, the wider side of the trapezoidal cross-section is at the bottom and the narrower side is at the top. When all screws are evenly spaced and subjected to uniform force, the point of application of the resultant force formed by the tension of all screws is not at the same location as the point of application of the external pressure formed by the expansion inside the electrolytic chamber. The point of application of the pressure formed by the expansion inside the electrolytic chamber is higher than the point of application of the resultant force formed by the tension of the screws. Therefore, during the operation of the electrolytic cell, an upward arching moment is formed in the middle of the main body of the electrolytic cell, opposite to the downward bending moment formed by the gravity of the electrolytic cell. In this way, the horizontally placed main body of the electrolytic cell effectively reduces the tendency of the middle of the main body to sag, and the greater the electrolytic pressure, the better the mitigation effect.

[0025] 2. Improved the support strength at both ends:

[0026] For a simply supported beam structure, besides the maximum bending stress in the middle of the beam, the two ends bear the maximum shear stress. The electrode frame of the main electrode plate of the electrolytic cell is now modified from the existing cylindrical pin holes for positioning and fixing to an improved version. The electrode frame has trapezoidal, triangular, or arc-shaped protrusions on both sides, and a corresponding trapezoidal, triangular, or arc-shaped groove on the other side. During installation, the protrusions (or grooves) on the insulating plate fixed to the end plate match the grooves (or protrusions) on the electrode frame. For example, for a 2000*2000 electrolytic cell, assuming the width of the protrusion (or groove) is 15mm and the height is 4mm, its compressive stress and shear stress are only 1 / 8 and 1 / 12.7 of those of six φ30mm diameter positioning pins, respectively. That is, without changing the material, the compressive strength and shear strength are 8 times and 12.7 times that of the existing structure, respectively.

[0027] 3. Improved raw material utilization rate:

[0028] The components of an electrolytic cell include a nickel mesh serving as the cathode and anode plates, an electrode frame, a nipple plate inside the electrode frame, a sealing gasket, and a diaphragm. Existing electrolytic cells are all circular in structure. During component processing, the four corners of the square raw material must be removed, resulting in structural waste and a maximum material utilization rate of only 78.5%. This patent replaces all the aforementioned components with trapezoidal structures. When arranging the raw materials for the components, a forward-backward-forward-backward… alternating pattern can be used. For example, if the four corners of the trapezoid are replaced with R400 rounded corners, and the included angle between the two sides of the trapezoid is 25°, when the rounded corners of the trapezoidal raw material are removed, the maximum material utilization rate is over 93%, significantly reducing the material cost of the electrolytic cell.

[0029] 4. Increased the reaction area of ​​the electrolysis chamber unit:

[0030] The electrolysis chamber of the electrolytic cell is a trapezoidal electrolysis chamber with internal dimensions of 1760*1760 mm, an included angle of 25° between the two side edges, and a radius of R280 mm at the corners. Its effective area is 2.56 m². 2 The existing circular electrolysis chamber, with a diameter of φ1760, has an effective area of ​​2.43m². 2 The effective area of ​​the electrolysis unit in this patent is increased by more than 5%. Under the same gas production rate per unit area, the number of electrolysis chamber units can be reduced, thereby reducing the length of the electrolysis cell. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the present invention;

[0032] Figure 2 This is a front view of the pole frame of the present invention;

[0033] Figure 3 This is a cross-sectional schematic diagram of the first type of pole frame in an embodiment of the present invention;

[0034] Figure 4 This is a cross-sectional schematic diagram of the second type of pole frame in an embodiment of the present invention;

[0035] Figure 5 This is a cross-sectional schematic diagram of the third type of pole frame in an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the electrolytic cell of the present invention subjected to bending moment and load;

[0037] Figure 7 This is a diagram showing the bending moment curve of the electrolytic cell in this invention.

[0038] Figure 8 This is a diagram showing the shear stress curve of the electrolytic cell in this invention. Detailed Implementation

[0039] like Figure 1 As shown, a trapezoidal cross-section alkaline electrolytic cell includes an electrolytic cell body 10 and multiple electrolytic units disposed within the electrolytic cell body 10. Each electrolytic unit includes:

[0040] Polar frame 1;

[0041] The nipple plate 2 is fixedly installed in the middle of the pole frame 1;

[0042] The cathode support plate 3 is welded and fixed to one side of the nipple plate 2;

[0043] Anode support plate 4 is welded and fixed to the other side of nipple plate 2;

[0044] Cathode plate 5 is fixedly installed on cathode support plate 3;

[0045] Anode plate 6 is fixedly installed on anode support plate 4;

[0046] Sealing gasket 7 is installed on both sides of pole frame 1 to form bipolar plates.

[0047] Furthermore, the electrolytic cell body 10 has end plates 101 on both sides, a diaphragm 8 is provided between adjacent electrolytic units inside the electrolytic cell body 10, an insulating plate 9 is provided on the inner wall of the electrolytic cell body 10, and the electrolytic units and diaphragms 8 inside the electrolytic cell body 10 are arranged in sequence at intervals.

[0048] Furthermore, refer to Figure 2 The electrode frame 1 includes a frame body 11, with an electrolyte inlet 12 at the bottom of the frame body 11, a hydrogen outlet 13 and an oxygen outlet 14 at the top of the frame body 11, and a central cavity 15 for the intermediate electrolysis chamber.

[0049] The frame 11 is trapezoidal, with rounded corners 16 at all four corners, and the tilt angles of the two sides of the frame are 10° to 45°.

[0050] Furthermore, the frame 11 has a raised ridge 17 on the front side of the edge and a groove 18 corresponding to the raised ridge 17 on the back side of the edge. When adjacent electrolysis units are spliced ​​together, the raised ridge 17 of the frame 11 matches the groove 18 on the adjacent frame 11, and the diaphragm 8 is located between the adjacent frames 11.

[0051] Furthermore, refer to Figure 3 , Figure 4 , Figure 5 The cross-sectional shape of the protruding ridge 17 is consistent with the cross-sectional shape of the groove. The cross-sectional shape of the protruding ridge 17 is triangular, trapezoidal or arc-shaped. The height of the protruding ridge 17 is greater than the depth of the groove 18. The sealing gasket 7 is installed at the fitting position between the protruding ridge 17 and the groove 18.

[0052] Reference Figure 6 , Figure 7 , Figure 8 After assembly, the electrolytic cell is placed horizontally, forming a "simply supported beam structure" with end plates supporting both ends and the middle suspended. The "simply supported beam" is composed of multiple independent bipolar plates and diaphragms 8 stacked at intervals. The weight of the bipolar plates and electrolyte causes the "simply supported beam" to bear a uniformly distributed load. There is no surface tensile stress between the multiple independent components in the "simply supported beam," but rather the end plates 101 are tightened by screws, and the end plates 101 then secure the electrolytic cell body 10. For large electrolytic cells, an example is the existing H2 production capacity of 1000 Nm³. 3 The alkaline electrolytic cell, with a capacity of approximately 48 tons per hour, is horizontally positioned, with the main body weighing approximately 48 tons and a span of approximately 4.5 meters between the two end plates 101 that are suspended in the middle. Consequently, the maximum bending moment in the middle of the electrolytic cell can reach 270,000 Nm. Therefore, the bending moment and shear stress on the electrolytic cell cannot be ignored. In severe cases, this can cause deflection and sagging in the middle of the main body of the electrolytic cell, affecting its sealing performance, reducing its lifespan, and compromising the consistency of performance parameters among the various electrolysis units.

[0053] The electrode frame 1 is an isosceles trapezoidal ring plate with a certain curvature at the top and bottom bases and rounded corners. The included angle θ between the two sides of the trapezoid is such that when the electrolytic cell is placed horizontally, the bottom edge (long side) of the electrode frame 1 faces downwards. Compared with the existing circular structure, the trapezoidal structure requires less processing waste 19, thus improving the utilization rate of raw materials. For example, when θ = 30° and the width and height of the trapezoid are equal, the material utilization rate is 93%, and the smaller θ is, the higher the utilization rate. In contrast, the material utilization rate of the circular structure is only 78.5%. For the electrolytic cell, its main components, including the electrode frame 1, the nipple plate 2, the anode and cathode support plates, the anode and cathode plates, the diaphragm 8, and the sealing gasket 7, all improve the utilization rate of raw materials. This trapezoidal structure electrolytic cell is particularly important for mass production.

[0054] Furthermore, due to the asymmetry between the upper and lower parts of the trapezoidal structure, the point of application of the resultant force of the surrounding screws does not coincide with the center of gravity of the electrolysis chamber. An example is attached. Figure 6 The pressure point F inside the electrolytic cell 压力 Above, at the point of application F of the resultant force of the surrounding screws. 端板 Below, the two forces create a constant bending moment M (negative) with a central arch on the vertical cross-section of the electrolytic cell. 压 The magnitude of the bending moment is directly proportional to the pressure inside the electrolysis chamber. The weight Q of the horizontally placed main electrolytic cell component creates a downward (positive) bending moment M in the middle. 重 Its value is a function of the parabola at points along the length L of the electrolytic cell, with the maximum bending moment at the middle and zero at both ends. An example is attached. Figure 7 M 压 and M 重 The sum of the two bending moments forms the resultant bending moment M. 合 The graph shows that the sum of the two bending moments reduces the maximum bending moment in the middle of the electrolytic cell, thus improving the bending resistance of the horizontally placed electrolytic cell.

[0055] For example, when θ = 30° and the pressure inside the electrolytic cell is 1.6 MPa, the maximum bending moment in the middle of the horizontally placed electrolytic cell can be reduced by about 10%. The greater the pressure inside the electrolytic cell, the more the maximum bending moment in the middle of the electrolytic cell is reduced, and the stronger the bending resistance of the electrolytic cell.

[0056] Each of the two sides of the pole frame 1 has a raised ridge 17 and a groove 18 in the middle. The raised ridge 17 and the groove 18 are similar in shape, and can be trapezoidal, triangular, or arc-shaped cross-sections, located at the same position on both sides of the pole frame. When assembling and stacking, the raised ridge (groove) of the subsequent pole frame mates with the groove (raised ridge) of the previous pole frame to form a self-positioning structure. Compared with traditional pin positioning, the advantages of this method are convenient installation, high load-bearing capacity, no need to drill holes in the diaphragm, and reduced risk of leakage and short circuit.

[0057] The height of the convex ridge 17 is twice the depth of the groove 18, which is twice the thickness of the compressed sealing gasket 7. When the electrolytic cells are assembled and stacked, the top surface of the convex ridge and the bottom of the groove clamp the diaphragm tightly, which limits the compression of the sealing gasket. Its beneficial effect is that the electrolytic cells are assembled and stacked with high precision, which is not affected by the elastomer and ensures the assembly accuracy of the electrolytic cells.

[0058] Meanwhile, compared to traditional pin positioning, the cross-sectional area of ​​the shear surface of the convex rib 17 is significantly increased. For example, the cross-sectional area of ​​a trapezoidal convex rib with a width of 15mm, a height of 4mm, and a horizontal projection length of 1800mm is 12.7 times the sum of the cross-sectional areas of six φ30 circles. (See attached image.) Figure 8As shown, the maximum shear stress in the main body of the electrolytic cell is located at both ends, and its magnitude is τ = N / A. Under constant gravity, the magnitude of the shear stress is inversely proportional to the cross-sectional area where the shear stress occurs. Therefore, the shear stress of the structure described in this patent is 1 / 12.7 of that of the six pins with a diameter of φ30mm.

[0059] When the trapezoidal cross-section alkaline electrolytic cell described in this patent is placed horizontally, its reaction area (monomer electrolysis chamber area) is larger than that of existing circular cross-section electrolytic cells with consistent length, width, and height. With the maximum width, height, and corner radii of the electrode frame 1 all consistent, when θ = 30°, the reaction area is 1.7% larger than that of the circular structure. Furthermore, as θ decreases, the reaction area continues to increase, reaching 8.3% larger than that of the circular structure when θ = 20°.

[0060] In summary, this invention reduces the bending deflection (stiffness) in the middle of the electrolytic cell body: The center lines of the screws surrounding the electrolytic cell body and the shape of the electrolysis chamber are both isosceles trapezoids with sides at a certain angle. When the electrolytic cell is placed horizontally, the wider side of the trapezoidal cross-section is at the bottom and the narrower side is at the top. When all screws are evenly spaced and subjected to consistent forces, the point of application of the resultant force formed by the tension of all screws is not at the same location as the point of application of the external pressure formed by the expansion inside the electrolysis chamber. The point of application of the pressure formed by the expansion inside the electrolysis chamber is higher than the point of application of the resultant force formed by the tension of the screws. Therefore, during operation, an upward arching moment is formed in the middle of the electrolytic cell body, opposite to the downward bending moment caused by the gravity of the electrolytic cell. Thus, the horizontally placed electrolytic cell body effectively mitigates the downward tendency in the middle, and the greater the electrolytic pressure, the better the mitigation effect.

[0061] Improved end-support strength: For a simply supported beam structure, in addition to the maximum bending stress in the middle of the beam, the ends bear the maximum shear stress. The electrode frame of the main electrode plate of the electrolytic cell is now modified from the existing cylindrical pin hole positioning and fixing method to an improved version where the electrode frame has trapezoidal, triangular, or arc-shaped protrusions on both sides, and a corresponding trapezoidal, triangular, or arc-shaped groove on the other side. During installation, the protrusions (or grooves) on the insulating plate fixed to the end plate match the grooves (or protrusions) on the electrode frame. For example, for a 2000*2000 electrolytic cell, assuming the width of the protrusion (or groove) is 15mm and the height is 4mm, its compressive stress and shear stress are only 1 / 8 and 1 / 12.7 of those of six φ30mm diameter positioning pins, respectively. That is, without changing the material, the compressive strength and shear strength are 8 times and 12.7 times that of the existing structure, respectively.

[0062] Improved raw material utilization: The electrolytic cell components include nickel mesh as anode and cathode plates, electrode frames, nipple plates inside the electrode frames, sealing gaskets, and diaphragms. Existing electrolytic cell structures are all circular. During component processing, the four corners of the square raw materials need to be removed, resulting in structural waste. The maximum material utilization rate is only 78.5%. This patent changes the original components to trapezoidal structures. When the raw materials are cut and arranged, they can be arranged in a forward-backward-forward-backward... and so on. For example, if the four corners of the trapezoid are changed to R400 rounded corners and the included angle between the two sides of the trapezoid is 25°, when the rounded corners of the trapezoidal raw materials are removed, the maximum material utilization rate is over 93%, which greatly reduces the material cost of the electrolytic cell.

[0063] The reaction area of ​​the electrolysis chamber unit has been increased: the electrolysis chamber of the electrolytic cell is a trapezoidal electrolysis chamber with internal dimensions of 1760*1760 mm, an included angle of 25° between the two sides, and a radius of R280 mm at the corners, with an effective area of ​​2.56 m². 2 The existing circular electrolysis chamber, with a diameter of φ1760, has an effective area of ​​2.43m². 2 The effective area of ​​the electrolysis unit in this patent is increased by more than 5%. Under the same gas production rate per unit area, the number of electrolysis chamber units can be reduced, thereby reducing the length of the electrolysis cell.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A trapezoidal cross-section alkaline electrolytic cell, comprising an electrolytic cell body and a plurality of electrolytic units disposed within the electrolytic cell body, characterized in that, The electrolysis unit includes: Polar frame; The nipple plate is fixedly installed in the middle of the pole frame; A cathode support plate is fixed to one side of the nipple plate; An anode support plate is fixed to the other side of the nipple plate; The cathode plate is fixedly mounted on the cathode support plate; The anode plate is fixedly mounted on the anode support plate; A sealing gasket is installed on both sides of the electrode frame to form a bipolar plate.

2. The trapezoidal cross-section alkaline electrolytic cell according to claim 1, characterized in that, A diaphragm is provided between adjacent electrolysis units within the main body of the electrolytic cell.

3. The trapezoidal cross-section alkaline electrolytic cell according to claim 1, characterized in that, An insulating plate is provided on the inner wall of the main body of the electrolytic cell.

4. The trapezoidal cross-section alkaline electrolytic cell according to claim 2, characterized in that, The electrolysis units and diaphragms are arranged sequentially and at intervals within the main body of the electrolytic cell.

5. A trapezoidal cross-section alkaline electrolytic cell according to any one of claims 1 to 4, characterized in that, The electrode frame includes a frame body, with an electrolyte inlet at the bottom of the frame body and a hydrogen outlet and an oxygen outlet at the top of the frame body. The central cavity of the frame body is an electrolysis chamber.

6. The trapezoidal cross-section alkaline electrolytic cell according to claim 5, characterized in that, The frame is trapezoidal, with rounded corners at all four corners, and the inclination angles of the two sides of the frame are 10° to 45°.

7. The trapezoidal cross-section alkaline electrolytic cell according to claim 2, characterized in that, The frame has a raised ridge on the front edge and a groove on the back edge corresponding to the raised ridge.

8. The trapezoidal cross-section alkaline electrolytic cell according to claim 7, characterized in that, When adjacent electrolysis units are spliced ​​together, the protruding ridges of the frame match the grooves on the adjacent frames, and the diaphragm is located between the adjacent frames.

9. The trapezoidal cross-section alkaline electrolytic cell according to claim 7, characterized in that, The cross-sectional shape of the protruding ridge is consistent with the cross-sectional shape of the groove, and the cross-sectional shape of the protruding ridge is triangular, trapezoidal, or arc-shaped.

10. The trapezoidal cross-section alkaline electrolytic cell according to claim 7, characterized in that, The height of the convex ridge is greater than the depth of the groove, and the sealing gasket is installed at the fitting position between the convex ridge and the groove.

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