Electrolytic cell structure

Abstract

To provide an electrolytic cell structure capable of improving power unit consumption and sodium hydroxide production.SOLUTION: An electrolytic cell structure comprises: a frame having a bottom surface and an opening located above the bottom surface; an electrode disposed on the opening side and having a substantially rectangular shape with a short side L1 (m)×long side L2 (m); a rib provided on the bottom surface and supporting the electrode; a baffle plate fixed to the rib and having a substantially rectangular shape with a short side L3 (m)×long side L4 (m), wherein the short side L1 is 1.3 m or more and 1.6 m or less, and the ratio of the long side L4 to the short side L1 is L4 / L1 of 0.35 or more and 0.97 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] This application relates to an electrolytic cell structure.

Background Art

[0002] Alkali metal salt electrolysis is a method of electrolyzing an aqueous solution of an alkali metal chloride such as brine (hereinafter, also simply referred to as "electrolysis") to produce a high-concentration alkali metal hydroxide, hydrogen, chlorine, etc. Examples of the method include electrolysis by the mercury method and the diaphragm method. In recent years, the ion exchange membrane method with good power efficiency has been mainly used.

[0003] In the ion exchange membrane method, electrolysis is performed using an electrolytic cell having an anode and a cathode (hereinafter, these are collectively also referred to as "electrodes") and arranging a large number of electrolytic cells through an ion exchange membrane. The electrolytic cell has a structure in which a cathode chamber with a cathode attached and an anode chamber with an anode attached are arranged back-to-back via a partition wall (back plate). In the electrolytic cell, an aqueous solution of an alkali metal chloride is supplied to the anode chamber, and an alkali metal hydroxide is supplied to the cathode chamber, and electrolysis is performed. Thus, chlorine gas is generated in the anode chamber, and an alkali metal hydroxide and hydrogen gas are generated in the cathode chamber.

[0004] In recent years, in order to further improve the power consumption per unit, zero-gap electrolysis in which an ion exchange membrane and a cathode are brought into contact for electrolysis has become the mainstream. For example, Patent Document 1 discloses a technique related to a unit cell for a bipolar filter press type electrolytic cell for an aqueous solution of an alkali metal chloride.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the technology described in Patent Document 1, a unit cell with a width of 2400 mm and a height of 1280 mm is disclosed, and it is said that a baffle plate can be provided at the upper part of the anode chamber of the unit cell. However, in such a configuration, there is room for improvement from the viewpoints of power consumption per unit and sodium hydroxide production amount.

[0007] The present invention has been made in view of such points, and an object thereof is to provide an electrolytic cell structure capable of improving power consumption per unit and sodium hydroxide production amount.

Means for Solving the Problems

[0008] As a result of intensive studies, the present inventor has found that the above points can be solved by an electrolytic cell structure having a predetermined configuration, and has completed the present invention.

[0009] That is, the present invention includes the following aspects. [1] An electrolytic cell structure, comprising: a frame body F1 having a bottom surface and an open portion located above the bottom surface; an electrode E1 disposed on the open portion side and having a substantially rectangular shape with a short side L1 (m) × a long side L2 (m); a rib R1 provided on the bottom surface and supporting the electrode E1; a baffle plate B1 fixed to the rib and having a substantially rectangular shape with a short side L3 (m) × a long side L4 (m); and wherein the short side L1 is 1.3 m or more and 1.6 m or less; an electrolytic cell structure, wherein a ratio of the long side L4 to the short side L1, as L4 / L1, is 0.35 or more and 0.97 or less. [2] further comprising a gas-liquid separation portion having a substantially rectangular parallelepiped shape and separating gas from the electrolytic solution; when the energized surface in the electrolytic cell structure is viewed in plan, the gas-liquid separation portion has a substantially rectangular shape with a short side L5 (m) × a long side L6 (m); The ratio of the short side L5 to the short side L1, expressed as L5 / L1, is 0.03 or more and 0.08 or less, for the electrolytic cell structure according to [1]. [3] The ratio of the volume V1 of the electrode chamber defined by the frame F1 and the electrode E1 to the volume V2 of the gas-liquid separation section, expressed as V1 / V2, is 15 or more and 20 or less, for the electrolytic cell structure according to [2]. [4] The angle formed by the electrode E1 and the baffle plate B1 is 0.5° or more and 2.4° or less, for the electrolytic cell structure according to any one of [1] to [3]. [5] The electrolytic cell structure further includes an electrode E2 and a conductive mattress that presses the energization surface of the electrode E2. The electrode E1 is an anode, and the electrode E2 is a cathode, for the electrolytic cell structure according to any one of [1] to [4]. [6] A plurality of the electrolytic cell structures according to claim 1, An ion exchange membrane disposed between adjacent ones of the electrolytic cell structures, Connecting means configured to connect the electrolytic cell structure and the ion exchange membrane, An electrolytic cell comprising the above. [7] The connecting means includes a press and a fixed head connected to the press, The fixed head is configured to press the entire surface of the contact surface with the electrolytic cell structure in the electrolytic cell structure by driving the press, for the electrolytic cell according to [6]. [8] The electrolytic cell further includes a dummy cell between the electrolytic cell structure closest to the connecting means and the connecting means, The connecting means includes a press and a fixed head connected to the press, The fixed head is configured to press the dummy cell by driving the press, The dummy cell is configured to press the entire surface of the contact surface with the electrolytic cell structure in the electrolytic cell structure under the pressing force from the fixed head, for the electrolytic cell according to [6]. [9] The electrolytic cell according to [8], wherein the dummy cell is a rigid material.

[10] Further comprising an attachment configured to fit into the connecting means, The connecting means includes a press and a fixed head connected to the press, The fixed head is configured to be able to press the attachment by driving the press, The electrolytic cell according to [6], wherein the attachment is configured to press the entire surface of the contact surface with the attachment in the electrolytic cell structure under the pressure from the fixed head.

[11] The electrolytic cell according to

[10] , wherein the attachment is a rigid material. [Advantages of the Invention]

[0010] According to the present invention, it is possible to provide an electrolytic cell structure capable of improving the power unit and the production amount of sodium hydroxide. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

[0012] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an exemplification for explaining the present invention and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of its gist. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted. Also, the positional relationships such as up, down, left, and right in the drawings are based on the positional relationships shown in the drawings unless otherwise specified, and the dimensional ratios in the drawings are not limited to the illustrated ratios. However, the drawings merely show an example of the present embodiment, and the present embodiment is not construed as being limited thereto.

[0013] The electrolytic cell structure of this embodiment includes a frame body F1 having a bottom surface and an open portion located above the bottom surface, an electrode E1 arranged on the open portion side and having a substantially rectangular shape with a short side L1 (m) × a long side L2 (m), a rib R1 provided on the bottom surface and supporting the electrode E1, and a baffle plate B1 fixed to the rib and having a substantially rectangular shape with a short side L3 (m) × a long side L4 (m). The short side L1 is 1.3 m or more and 1.6 m or less, and the ratio of the long side L4 to the short side L1, expressed as L4 / L1, is 0.35 or more and 0.97 or less. Since the electrolytic cell structure of this embodiment is configured in this way, the power unit and the sodium hydroxide production amount can be improved.

[0014] 〔Electrolytic Cell〕 In this embodiment, the term "electrolytic cell structure" is used to refer to a part or the whole of the structure of the electrolytic cell. That is, the electrolytic cell structure of this embodiment may refer to the structure on the anode chamber side of the electrolytic cell, or may refer to the structures on both the anode chamber side and the cathode chamber side. Hereinafter, taking the case where the electrolytic cell structure of this embodiment is applied to an electrolytic cell as an example, it will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating the configuration of the electrolytic cell structure 50. In the example of FIG. 1, the electrolytic cell structure 50 includes an anode chamber 60, a cathode chamber 70, a partition wall 80 installed between the anode chamber 60 and the cathode chamber 70, an anode 11 installed in the anode chamber 60, and a cathode 21 installed in the cathode chamber 70. As shown in FIG. 1, if necessary, a reverse current absorber 18 installed in the cathode chamber may be provided. The cathode chamber 70 further includes a current collector 23, a support 24 that supports the current collector, and a metal elastic body 22. The metal elastic body 22 is installed between the current collector 23 and the cathode 21. The support 24 is installed between the current collector 23 and the partition wall 80. The current collector 23 is electrically connected to the cathode 21 via the metal elastic body 22. The partition wall 80 is electrically connected to the current collector 23 via the support 24. Therefore, the partition wall 80, the support 24, the current collector 23, the metal elastic body 22, and the cathode 21 are electrically connected. It is preferable that the entire surface of the cathode 21 is coated with a catalyst layer for the reduction reaction. Further, the form of electrical connection may be such that the partition wall 80 and the support 24, the support 24 and the current collector 23, and the current collector 23 and the metal elastic body 22 are directly attached to each other, and the cathode 21 is laminated on the metal elastic body 22. Examples of the method of directly attaching these constituent members to each other include welding.

[0015] FIG. 2 is a cross-sectional view of two adjacent electrolytic cell structures 50 in the electrolytic cell 4. FIG. 3 shows the electrolytic cell 4. FIG. 4 shows the process of assembling the electrolytic cell 4.

[0016] As shown in FIG. 2, an electrolytic cell structure 50, a cation exchange membrane 51, and the electrolytic cell structure 50 are arranged in series in this order. A cation exchange membrane 51 is disposed between the anode chamber of one electrolytic cell structure 50 and the cathode chamber of the other electrolytic cell structure 50 among two adjacent electrolytic cells in the electrolytic cell. That is, the anode chamber 60 of the electrolytic cell structure 50 and the cathode chamber 70 of the adjacent electrolytic cell structure 50 are separated by the cation exchange membrane 51. As shown in FIG. 3, the electrolytic cell 4 is composed of a plurality of electrolytic cell structures 50 connected in series via the cation exchange membrane 51. That is, the electrolytic cell 4 is a bipolar electrolytic cell including a plurality of electrolytic cell structures 50 arranged in series and a cation exchange membrane 51 disposed between adjacent electrolytic cell structures 50. As shown in FIG. 4, the electrolytic cell 4 is assembled by arranging a plurality of electrolytic cell structures 50 in series via the cation exchange membrane 51 and connecting them by a press 5.

[0017] The electrolytic cell 4 has an anode terminal 7 and a cathode terminal 6 connected to a power source. The anode 11 of the electrolytic cell structure 50 located at the outermost end among the plurality of electrolytic cell structures 50 connected in series in the electrolytic cell 4 is electrically connected to the anode terminal 7. The cathode 21 of the electrolytic cell located at the end on the opposite side of the anode terminal 7 among the plurality of electrolytic cells 2 connected in series in the electrolytic cell 4 is electrically connected to the cathode terminal 6. The current during electrolysis flows from the anode terminal 7 side, through the anode and cathode of each electrolytic cell structure 50, and toward the cathode terminal 6. Note that an electrolytic cell having only an anode chamber (anode terminal cell) and an electrolytic cell having only a cathode chamber (cathode terminal cell) may be disposed at both ends of the connected electrolytic cell structures 50. In this case, the anode terminal 7 is connected to the anode terminal cell disposed at one end, and the cathode terminal 6 is connected to the cathode terminal cell disposed at the other end.

[0018] When performing electrolysis of brine, brine is supplied to each anode chamber 60, and pure water or a low-concentration sodium hydroxide aqueous solution is supplied to the cathode chamber 70. Each liquid is supplied from an electrolytic solution supply pipe (omitted in the figure) to each electrolytic cell structure 50 via an electrolytic solution supply hose (omitted in the figure). Further, the electrolytic solution and the products of electrolysis are recovered from an electrolytic solution recovery pipe (omitted in the figure). In electrolysis, sodium ions in the brine move from the anode chamber 60 of one electrolytic cell structure 50 through the cation exchange membrane 51 to the cathode chamber 70 of the adjacent electrolytic cell structure 50. Therefore, the current during electrolysis flows along the direction in which the electrolytic cell structures 50 are connected in series. That is, the current flows from the anode chamber 60 to the cathode chamber 70 through the cation exchange membrane 51. Along with the electrolysis of brine, chlorine gas is generated on the anode 11 side, and sodium hydroxide (solute) and hydrogen gas are generated on the cathode 21 side.

[0019] (Anode chamber) An embodiment in which the electrode E1 included in the electrolytic cell structure of the present embodiment is a member on the anode chamber 60 side, that is, a case corresponding to the anode 11 will be described as an example. FIG. 5 is a front view of the electrolytic cell structure 50 of FIG. 1 from the direction α (that is, the anode 11 side). As shown in FIG. 5, the anode 11 (corresponding to the aforementioned "electrode E1") is arranged so as to be surrounded by a frame body 101 (corresponding to the aforementioned "frame body F1"), and has a substantially rectangular shape with a short side L1 (m) × a long side L2 (m). The anode chamber 60 is partitioned by the frame body 101 and the anode 11. In FIG. 5, on the back side of the anode 11 (the partition wall 80 side) in the drawing, a baffle plate 103 (corresponding to the aforementioned "baffle plate B1") having a substantially rectangular shape with a short side L3 (m) × a long side L4 (m) is arranged. Further, above the anode 11, the baffle plate 103, and the frame body 101, an anode-side gas-liquid separation unit 104 for separating gas from the electrolytic solution mixed with gas is arranged. Unless otherwise specified, the upper direction means the upward direction in the electrolytic cell structure 50 of FIG. 1, and the lower direction means the downward direction in the electrolytic cell structures 50 of FIGS. 1 and 5. Hereinafter, the configuration shown in FIG. 5 will be further described with reference to FIGS. 6 to 8 as well.

[0020] FIG. 6(A) is a view of the x-x' cross-section of the electrolytic cell structure 50 shown in FIG. 5 as observed from direction β. As shown in FIG. 6(A), the frame body 101 has a bottom surface 101a and an opening 101b located above the bottom surface 101a (above in FIG. 6(A)). As shown in FIG. 6(A), the frame body 101 may be configured such that side wall portions erected from the bottom surface 101a define the opening 101b. The anode 11 is disposed on the opening 101b side of the frame body 101. Based on the long side L2 of the anode 11, the size of the opening 101b can be set. Further, ribs 102 (corresponding to the aforementioned "rib R1") are provided on the bottom surface 101a of the frame body 101. The ribs 102 support the anode 11. The baffle plate 103 is fixed by the ribs 102. In the example of FIG. 6(A), the baffle plate 103 is fixed by a method such as welding between two ribs 102. Based on the short side L3, the distance between the two ribs 102 can be set. The ribs 102 may be a conductive member, may be a metal flat plate, or may be a metal flat plate having pores. A seal surface 101c is formed on the frame body 101 so as to extend from the aforementioned side wall portion. When two electrolytic cell structures 50 are brought into close contact with each other to ensure airtightness during electrolyte flow, the seal surface 101c is pressed. In the present embodiment, when ensuring airtightness, the anode 11 may also be arranged to be pressed.

[0021] In the present embodiment, the short side L1 of the anode 11 is set to be 1.3 m or more and 1.6 m or less. When L1 is 1.3 m or more, the power unit and the sodium hydroxide production amount can be improved. Further, when L1 is 1.6 m or less, the handleability as an electrolytic cell can be ensured. From the above viewpoints, the short side L1 is preferably 1.35 m or more and 1.55 m or less, and more preferably 1.4 m or more and 1.5 m or less.

[0022] As the anode 11, a metal electrode such as so-called DSA (registered trademark) can be used. DSA is an electrode of a titanium substrate whose surface is coated with an oxide containing ruthenium, iridium, and titanium as components. The shape is not particularly limited as long as it has a substantially rectangular shape of short side L1 (m) × long side L2 (m), and any of punching metal, non-woven fabric, foamed metal, expanded metal, metal porous foil formed by electroforming, so-called woven mesh made by knitting metal wires, etc. can be used.

[0023] The long side L2 of the anode 11 is not particularly limited and may be 2.0 m or more and 2.8 m or less, may be 2.1 m or more and 2.6 m or less, or may be 2.2 m or more and 2.5 m or less.

[0024] An electrolytic solution is supplied to the anode chamber 60 from an anode-side electrolytic solution supply section (not shown). The anode-side electrolytic solution supply section is preferably disposed below the anode chamber 60 (below in FIG. 1). As the anode-side electrolytic solution supply section, for example, a pipe (dispersion pipe) having an opening formed on the surface can be used. It is more preferable that such a pipe is disposed parallel to the lower part 19 of the electrolytic cell along the surface of the anode 11. This pipe is connected to an electrolytic solution supply pipe (liquid supply nozzle) that supplies the electrolytic solution into the electrolytic cell structure 50. The electrolytic solution supplied from the liquid supply nozzle is conveyed into the electrolytic cell structure 50 by the pipe and supplied into the anode chamber 60 through the opening provided on the surface of the pipe. It is preferable to dispose the pipe parallel to the lower part 19 of the electrolytic cell along the surface of the anode 11 because the electrolytic solution can be uniformly supplied into the anode chamber 60.

[0025] The baffle plate 103 is not particularly limited as long as it has a substantially rectangular shape with a short side L3 (m) × a long side L4 (m), and functions as a partition plate for controlling the flow of the electrolytic solution in the anode chamber 60. The baffle plate 103 may be a conductive member and may be a metal flat plate. By providing the baffle plate 103, the electrolytic solution (such as brine) can be internally circulated in the anode chamber 60 to make its concentration uniform. In order to cause internal circulation, the baffle plate 103 is preferably arranged so as to separate the space near the anode 11 from the space near the partition wall 80. From the above viewpoints, the baffle plate 103 is preferably provided so as to face the surfaces of the anode 11 and the partition wall 80. In the space near the anode 11 partitioned by the baffle plate 103, as electrolysis proceeds, the concentration of the electrolytic solution (brine concentration) decreases, and generated gases such as chlorine gas are generated. As a result, a gas-liquid specific gravity difference is generated between the space near the anode 11 partitioned by the baffle plate 103 and the space near the partition wall 80. Utilizing this, the internal circulation of the electrolytic solution in the anode chamber 60 can be promoted, and the concentration distribution of the electrolytic solution in the anode chamber 60 can be made more uniform. To explain the function of such a baffle plate 103, FIG. 7 shows a state of observing the y-y' cross-section of the electrolytic cell structure 50 shown in FIG. 5 from the direction γ. Note that y-y' is a line drawn so as to pass between the two ribs 102 in FIG. 5, and the y-y' cross-section corresponds to the cross-sectional view of the baffle plate 103 located between the two ribs 102. That is, the baffle plate 103 shown in FIG. 7 is fixed between two ribs 102 not shown in FIG. 7. As shown in FIG. 7, the electrolytic solution is supplied upward from the lower part 19 of the electrolytic cell. However, due to the presence of the baffle plate 103, the electrolytic solution flows upward (direction F1) on the anode 11 side of the baffle plate 103, and then the flow direction reverses (direction F2) at the upper part in the anode chamber 60 (above the baffle plate 103). After that, the electrolytic solution flows downward (direction F3) on the frame body 101 side of the baffle plate 103. In this way, the baffle plate 103 tends to improve the circulation of the electrolytic solution in the anode chamber 60. In the present embodiment, when L1 of the anode 11 is 1.3 m or more, the power unit and the sodium hydroxide production amount can be improved. On the other hand, as L1 increases, the circulation of the electrolytic solution tends to decrease.Therefore, in the present embodiment, the ratio (L4 / L1) of the long side L4 of the baffle plate 103 to the short side L1 of the anode 11 is set to be 0.35 or more and 0.97 or less. When L4 / L1 is within this range, the circulation of the electrolytic solution is improved. Thus, in the present embodiment, by setting the short side L1 of the anode 11 to be 1.3 m or more and 1.6 m or less, and setting the ratio (L4 / L1) of the long side L4 of the baffle plate 103 to the short side L1 of the anode 11 to be 0.35 or more and 0.97 or less, it is possible to improve the power unit and the production amount of sodium hydroxide while ensuring the circulation of the electrolytic solution. From the above viewpoints, L4 / L1 is preferably 0.40 or more and 0.9 or less, and more preferably 0.50 or more and 0.88 or less.

[0026] The long side L4 of the baffle plate 103 is not particularly limited and may be 0.5 m or more and 1.35 m or less, may be 0.8 m or more and 1.3 m or less, or may be 0.9 m or more and 1.25 m or less. Also, the short side L3 of the baffle plate 103 is not particularly limited and may be 0.05 m or more and 0.15 m or less, may be 0.07 m or more and 0.12 m or less, or may be 0.09 m or more and 0.11 m or less.

[0027] In FIG. 7, an example in which the baffle plate 103 is arranged parallel to the anode 11 and the frame body 101 (partition wall 80) is shown, but the present invention is not limited thereto. That is, the baffle plate 103 may be arranged inclined with respect to the anode 11 and the frame body 101 (partition wall 80). FIG. 8 is a diagram showing an example in which the baffle plate 103 is arranged inclined at an angle θ with respect to the anode 11. The baffle plate 103 shown in FIG. 8 is fixed between two ribs (not shown). In the present embodiment, from the viewpoint of the circulation of the electrolytic solution, the angle formed by the anode 11 and the baffle plate 103 (that is, the angle θ) is preferably 0.5° or more and 2.4° or less, more preferably 0.6° or more and 2.0° or less, and still more preferably 0.7° or more and 1.5° or less.

[0028] As shown in FIG. 5, it is preferable that the electrolytic cell structure 50 in the present embodiment is provided with an anodic gas-liquid separation section 104 for separating gas and liquid. The anodic gas-liquid separation section 104 may include, for example, an electrolytic solution inlet, a gas outlet, and an electrolytic solution outlet (all not shown). During electrolysis, when the generated gas such as chlorine gas and the electrolytic solution generated in the electrolytic cell structure 50 become a mixed phase (gas-liquid mixed phase) and are discharged to the outside of the system, vibration tends to occur due to pressure fluctuations inside the electrolytic cell structure 50. When the anodic gas-liquid separation section 104 is provided, physical damage to the ion exchange membrane caused by such vibration can tend to be suppressed. From the above viewpoints, it is preferable that an antifoaming plate for eliminating bubbles is installed in the anodic gas-liquid separation section. When the gas-liquid mixed-phase flow passes through the antifoaming plate, the bubbles burst, so that the electrolytic solution and the gas can be separated. As a result, vibration during electrolysis can be prevented. As shown in FIG. 5, the anodic gas-liquid separation section 104 may have a substantially rectangular parallelepiped shape. When the energized surface in the electrolytic cell structure is viewed in plan, that is, when observing the electrolytic cell structure 50 from the anode 11 side as shown in FIG. 5, the shape of the anodic gas-liquid separation section 104 preferably has a substantially rectangular shape with a short side L5 (m) × a long side L6 (m). At this time, the ratio (L5 / L1) of the short side L5 to the short side L1 is preferably 0.03 or more and 0.08 or less.

[0029] As shown in FIG. 6 and the like, the frame body 101 may be formed in a U-shaped cross section, and may be formed by shaping a plate made of nickel or titanium into a desired shape. The frame body 101 on the anode chamber side may be formed by shaping a plate made of titanium into a U-shaped cross section. The electrode chamber volume V1 of the anode chamber 60 can be obtained as the volume of the region partitioned by the virtual surface 101d defined by the sealing surface 101c in the frame body 101 and the frame body 101 (see FIG. 6(B)). In the example of FIG. 6, the anode 11 (energized surface) is arranged on the virtual surface 101d. Here, the ratio (V1 / V2) of the electrode chamber volume V1 of the anode chamber 60 to the volume V2 of the anodic gas-liquid separation section 104 is preferably 15 or more and 20 or less, more preferably 15.5 or more and 19.5 or less, and still more preferably 16 or more and 18.5 or less.

[0030] Although not shown in FIG. 1 and the like, a current collector may be separately provided inside the anode chamber 60. Such a current collector can have the same material and configuration as the current collector of the cathode chamber described later. Also, in the anode chamber 60, the anode 11 itself can function as a current collector.

[0031] (Cathode chamber) In the cathode chamber 70, the support 24, the current collector 23, the metal elastic body 22, and the cathode 21 may be arranged in this order. Also, these members may be electrically connected. Similar to the anode chamber 60, the cathode chamber 70 may also have a cathode-side electrolyte supply section and a cathode-side gas-liquid separation section. For example, in the aspect where the electrode E2 included in the electrolytic cell structure of the present embodiment is a member on the cathode chamber 70 side, that is, when corresponding to the cathode 21, the ratio (V1' / V2') of the cell volume V1' of the cathode chamber 70 to the volume V2' of the cathode-side gas-liquid separation section is preferably 15 or more and 20 or less, more preferably 15.5 or more and 19.5 or less, and even more preferably 16 or more and 18.5 or less. In addition, among the respective parts constituting the cathode chamber 70, the description of those similar to the respective parts constituting the anode chamber 60 will be omitted.

[0032] The cathode 21 preferably has a nickel substrate and a catalyst layer covering the nickel substrate. Examples of the components of the catalyst layer on the nickel substrate include metals such as Ru, C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and oxides or hydroxides of these metals. Examples of the method for forming the catalyst layer include plating, alloy plating, dispersion composite plating, CVD, PVD, thermal decomposition, and spraying. These methods may be combined. The catalyst layer may have a plurality of layers and a plurality of elements as required. Further, the cathode 21 may be subjected to a reduction treatment as required. Note that as the substrate of the cathode 21, nickel, a nickel alloy, iron, or a material obtained by plating nickel on stainless steel may be used. As the shape of the cathode 21, any of punching metal, non-woven fabric, foamed metal, expanded metal, a metal porous foil formed by electroforming, a so-called woven mesh formed by knitting metal wires, etc. can be used.

[0033] The current collector 23 has a function of enhancing the current collecting effect. The current collector 23 may be a perforated plate and may be arranged substantially parallel to the surface of the cathode 21. The current collector 23 is preferably made of an electrically conductive metal such as nickel, iron, copper, silver, titanium, etc. The current collector 23 may be a mixture, alloy, or composite oxide of these metals. Note that the shape of the current collector 23 may be any shape as long as it functions as a current collector, and may be plate-shaped or net-shaped.

[0034] By providing a metal elastic body 22 between the current collector 23 and the cathode 21, each cathode 21 of a plurality of electrolytic cell structures 50 connected in series is pressed against the cation exchange membrane 51, the distance between each anode 11 and each cathode 21 is shortened, and the voltage applied to the entire plurality of electrolytic cell structures 50 connected in series can be reduced. By reducing the voltage, the power consumption can be reduced. Further, by providing the metal elastic body 22, when the laminate including the electrolysis electrode in the present embodiment is installed in the electrolytic cell, the electrolysis electrode can be stably maintained in a fixed position by the pressing pressure of the metal elastic body 22. As the metal elastic body 22, a spring member such as a spiral spring or a coil, a cushioning mattress (conductive mattress), or the like can be used. As the metal elastic body 22, an appropriate one can be adopted in consideration of the stress for pressing the ion exchange membrane and the like. The metal elastic body 22 may be provided on the surface of the current collector 23 on the cathode chamber 70 side, or may be provided on the surface of the partition wall on the anode chamber 60 side. Usually, since the two chambers are partitioned so that the cathode chamber 70 is smaller than the anode chamber 60, from the viewpoint of the strength of the frame body and the like, it is preferable to provide the metal elastic body 22 between the current collector 23 of the cathode chamber 70 and the cathode 21. Further, the metal elastic body 23 is preferably made of a metal having electrical conductivity such as nickel, iron, copper, silver, or titanium. In the electrolytic cell structure of the present embodiment, as a member on the cathode chamber side, it is preferable to provide a conductive mattress that presses the current-carrying surface of the cathode 21 toward the ion exchange membrane side.

[0035] The cathode chamber 70 preferably includes a support 24 that electrically connects the current collector 23 and the partition wall 80. Thereby, current can flow efficiently. The support 24 is preferably made of a metal having electrical conductivity such as nickel, iron, copper, silver, or titanium. Further, the shape of the support 24 may be any shape as long as it can support the current collector 23, and may be rod-shaped, plate-shaped, or net-shaped. The support 24 is, for example, plate-shaped. A plurality of supports 24 are arranged between the partition wall 80 and the current collector 23. The plurality of supports 24 are arranged so that their respective surfaces are parallel to each other. The support 24 is arranged substantially perpendicular to the partition wall 80 and the current collector 23.

[0036] In the electrolytic cell structure of the present embodiment, a gasket may be disposed to seal between the ion exchange membrane and the electrolytic cell. Specific examples of the gasket include a frame-shaped rubber sheet having an opening formed at the center. The gasket is required to have resistance to corrosive electrolytes, generated gases, etc. and be usable for a long period of time. Therefore, from the viewpoints of chemical resistance and hardness, vulcanized products or peroxide crosslinked products of ethylene-propylene-diene rubber (EPDM rubber), ethylene-propylene rubber (EPM rubber), etc. are usually used as the gasket. Further, if necessary, a gasket coated with a fluororesin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) in a region (liquid contact portion) in contact with a liquid can also be used. These gaskets only need to have openings so as not to obstruct the flow of the electrolytic solution, and their shapes are not particularly limited. For example, a frame-shaped gasket is attached with an adhesive or the like along the periphery of each opening of the anode chamber frame constituting the anode chamber 60 or the cathode chamber frame constituting the cathode chamber 70. And, for example, when connecting two electrolytic cell structures 50 via a cation exchange membrane 51 (see FIG. 2), each electrolytic cell structure 50 with a gasket attached via the cation exchange membrane 51 may be tightened. Thereby, it is possible to suppress leakage of the electrolytic solution, alkali metal hydroxide, chlorine gas, hydrogen gas, etc. generated by electrolysis to the outside of the electrolytic cell structure 50. The anode-side gasket 12 is preferably disposed on the surface of the frame body constituting the anode chamber 60. The cathode-side gasket 13 is preferably disposed on the surface of the frame body constituting the cathode chamber 70. The electrolytic cells are connected such that the anode-side gasket 12 provided in one electrolytic cell and the cathode-side gasket 13 of the adjacent electrolytic cell sandwich the cation exchange membrane 51 (see FIG. 2). These gaskets can impart airtightness to the connection portion when connecting a plurality of electrolytic cell structures 50 in series via the cation exchange membrane 51.

[0037] 〔Electrolytic cell〕 The electrolytic cell of this embodiment includes an electrolytic cell structure. As a specific example of the electrolytic cell of this embodiment, there may be mentioned an electrolytic cell including a plurality of electrolytic cell structures, an ion exchange membrane disposed between adjacent electrolytic cell structures, and a connecting means configured to connect the electrolytic cell structure and the ion exchange membrane.

[0038] The ion exchange membrane in this embodiment is not particularly limited, and for example, a known one such as the ion exchange membrane described in International Publication No. 2018 / 174199 may be adopted.

[0039] The connecting means in this embodiment is not particularly limited. As an example, a press 5 as illustrated in FIGS. 3 to 4 may be adopted. In an example where the press 5 is used as the connecting means, during the operation of the electrolytic cell, it is preferable to sufficiently press the portions where the frames 101 face each other rather than the portions where the anode-side gas-liquid separation portions 104 of two adjacent electrolytic cell structures 50 face each other. By sufficiently pressing the portions where the frames 101 face each other, the airtightness of the portion that becomes the flow path of the electrolytic solution can be ensured, and leakage of the electrolytic solution during the operation of the electrolytic cell can be prevented.

[0040] In the example of FIG. 9(A), it is preferable to press around the central portion SC of the anode 11 (the central portion in the plane of the anode 11; the central portion of the current-carrying surface) rather than the central portion of the entire electrolytic cell structure 50 including the anode-side gas-liquid separation portion 104. In this case, it becomes easier to uniformly press the anode 11 and the seal surface 101c.

[0041] FIG. 9(B) is a diagram for explaining the relationship between the pressing position when the press 5 presses and connects a plurality (five in the example of FIG. 9(B)) of electrolytic cell structures 50p in the electrolytic cell and the central portion SC (central portion of the current-carrying surface). An ion exchange membrane is disposed between two adjacent electrolytic cell structures, but in FIG. 9(B), the ion exchange membrane is omitted. In the example of FIG. 9(B), the press 5 includes a cylinder SD and a loose head LH. A spherical seat SP is formed at the tip of the cylinder SD, and the spherical seat SP may be configured to be tilted in the direction of arrow PV, the front direction of the paper surface, the back direction of the paper surface, etc. As shown in FIG. 9(B), since the cylinder SD is fitted with the loose head LH at the spherical seat SP, the direction (pressing direction) of the loose head LH can be adjusted as appropriate, so that the pressing direction can be easily controlled. Here, as shown in FIG. 9(B), it is preferable that the spherical seat SP is arranged so as to overlap the central portion SC (central portion of the current-carrying surface). When arranged in this way, it becomes easier to selectively press the portion R2 where the plurality of electrolytic cell structures 50p are arranged against the portion R1 where the anode-side gas-liquid separation portions 104 are aligned.

[0042] Hereinafter, aspects that can be adopted when applying the electrolytic cell structure of the present embodiment to an existing electrolytic cell (for example, an electrolytic cell designed on the premise of storing an electrolytic cell including an electrode with a short side L1 of less than 1.3 m) will be described.

[0043] FIG. 10(A) is an explanatory view showing an electrolytic cell 4a designed on the premise of storing an electrolytic cell structure 50a including an electrode having a substantially rectangular shape with a short side of less than 1.3 m × a long side of L2 (m). In the electrolytic cell 4a, a plurality of electrolytic cell structures 50a are pressed toward the fixing head 8 by the press 5, whereby each electrolytic cell is connected and becomes in an operable state. When applying the electrolytic cell structure 50 including the electrolytic cell structure of the present embodiment to such an electrolytic cell 4a, that is, when applying the electrolytic cell structure 50 including an electrode having a substantially rectangular shape with a short side of 1.3 m or more and 1.6 m or less × a long side of L2 (m), the entire surface of the electrolytic cell structure 50 cannot be sufficiently pressed by the press 5, and the electrolytic performance may be affected. Therefore, as shown in FIG. 10(B), an electrolytic cell 4 including a press 5a designed to be larger than the press 5 and a fixing head 8a designed to be larger than the fixing head 8 can be employed. By designing the press 5a and the fixing head 8a according to the size of the electrode having a substantially rectangular shape with a short side of 1.3 m or more and 1.6 m or less × a long side of L2 (m), each electrolytic cell can be connected in a state where the entire surface of the electrolytic cell structure 50 is sufficiently pressed.

[0044] Also, as shown in Fig. 10(C), dummy cells 9a can be installed adjacent to each of the existing press 5 and the existing fixed head 8. By designing the dummy cell 9a to match the size of an electrode having a substantially rectangular shape with a short side of 1.3 m or more and 1.6 m or less and a long side of L2 (m), each electrolytic cell can be connected while fully pressing the entire surface of the electrolytic cell structure 50. The dummy cell 9a does not necessarily have to function as an electrolytic cell. For example, a cell having the same shape, size, weight, and strength as the electrolytic cell structure 50 may be used. As an example, the dummy cell 9a does not have electrolytic performance. The fact that the dummy cell 9a does not have electrolytic performance can be confirmed by the fact that no electrolysis reaction occurs when the electrolytic cell structure of the example is replaced with the dummy cell 9a in the electrolysis operation described in the examples below. Additionally, the fact that the dummy cell 9a does not have electrolytic performance can also be determined by the fact that the catalytic metal that can be used for the electrode is not used or that the catalytic metal is not arranged at a position where it can function as a catalyst.

[0045] In the present embodiment, from the viewpoint of uniform pressing, the dummy cell 9a is preferably a rigid material. The fact that the dummy cell 9a is a rigid material can be confirmed by the fact that no leakage of the electrolytic solution occurs when the dummy cell 9a is installed adjacent to each of the existing press 5 and the existing fixed head 8, and no deformation of the dummy cell 9a due to pressing is observed in the electrolysis operation described in the examples below. Additionally, the fact that the dummy cell 9a is a rigid material can also be determined by considering the material (Young's modulus) and thickness of the dummy cell 9a. For example, for a dummy cell with Young's modulus Y1 and thickness T1 and a dummy cell with Young's modulus Y2 and thickness T2, the values of Y1×T1 and Y2×T2 are obtained, and the one with the larger numerical value can be evaluated as having higher rigidity. In one embodiment, the rigidity of the dummy cell is the same as or greater than the rigidity of the electrolytic cell structure.

[0046] The material of the dummy cell 9a is not particularly limited. For example, it may be made of metal, and SS material (rolled steel for general structures) may be used.

[0047] The thickness of the dummy cell 9a is not particularly limited and may be, for example, 20 mm or more, 30 mm or more, or 60 mm or more. Further, the thickness of the dummy cell 9a may be, for example, 150 mm or less or 130 mm or less.

[0048] As shown in FIG. 10(D), the dummy cell 9a may be configured in a lattice shape. That is, the dummy cell 9a may be one in which a plurality of grids LP are formed in the main body portion DB. As the size and number of the grids LP increase, the weight of the dummy cell 9a tends to decrease, and as a result, the maintainability can be improved. On the other hand, as the size and number of the grids LP decrease, the rigidity of the dummy cell 9a tends to increase, and as a result, it can contribute to more uniform pressing. In the present embodiment, when the dummy cell 9a is configured in a lattice shape, from the viewpoint of ensuring rigidity, it is preferably 60 mm or more, and from the viewpoints of ensuring the number of installed electrolytic cell structures and ensuring electrolytic performance, it is preferably 130 mm or less.

[0049] Furthermore, as shown in FIG. 10(E), an attachment 9b can also be installed adjacent to each of the existing press 5 and the existing fixed head 8. By designing the attachment 9b to match the size of an electrode having a substantially rectangular shape with a short side of 1.3 m or more and 1.6 m or less and a long side L2 (m), each electrolytic cell can be connected in a state where the entire surface of the electrolytic cell structure 50 is sufficiently pressed. The attachment 9b has, for example, the same shape, size, and strength as the electrolytic cell structure 50, and can use one having a shape that fits the existing press 5 / the existing fixed head 8 on the surface that contacts the existing press 5 / the existing fixed head 8. In the present embodiment, from the viewpoint of uniform pressing, the attachment 9b is preferably a rigid material. The evaluation of the attachment 9b being a rigid material and the evaluation of the magnitude relationship of rigidity can be performed in the same manner as for the dummy cell 9a. In one embodiment, the rigidity of the attachment 9b is the same as or greater than the rigidity of the electrolytic cell structure.

[0050] In FIG. 10, an ion exchange membrane is disposed between two adjacent electrolytic cell structures, but the ion exchange membrane is omitted in these figures.

[0051] In FIGS. 9 to 10, although an example of a mode in which one press 5 connects the electrolytic cell structures is illustrated, in the present embodiment, the electrolytic cell structures may be connected by a plurality of pressing means. For example, a plurality of bolt-shaped pressing members (having a smaller pressing surface area than the press 5 in FIGS. 9 to 10, for example, a pressure bolt or the like) may be arranged at one end of the electrolytic cell, and the electrolytic cell structures may be pressed by these members in the same manner as the press 5.

[0052] In addition to those described above, the connecting means in the present embodiment may be a tie rod. The tie rod may be fixed, for example, by locking one end of the tie rod to the press 5, and the other end of the tie rod may be fixed by locking to the fixed head 8. The distance between such two fixing portions may be adjusted so that one end of the tie rod and the other end of the tie rod are attracted to each other, and all the electrolytic cell structures arranged therebetween may be configured to be connected.

[0053] In addition to the above, the connecting means in the present embodiment may be, for example, a through hole formed in the electrolytic cell structure as a part of the connecting mechanism. As shown in FIG. 6(A) and the like, the frame body 101 in the electrolytic cell structure 50 may have a seal surface 101c not covered by the anode 11, and one or a plurality of through holes may be provided in the seal surface 101c. A plurality of electrolytic cell structures configured in this way (each having a through hole at the same position) may be prepared, arranged in the electrolytic cell, and fixed using the tie rod as described above. For example, the tie rod may be passed through all of the through holes of the plurality of electrolytic cell structures, and both ends of the tie rod may be fixed by being locked in the through holes of the electrolytic cell structures at both ends, respectively. The distance between such two fixing portions may be adjusted so that one end of the tie rod and the other end of the tie rod are attracted to each other, and all the electrolytic cell structures arranged therebetween may be configured to be connected.

Example

[0054] The present embodiment will be described in more detail below based on examples. The present embodiment is not limited only to these examples.

[0055] [Example 1] A zero-gap type electrolytic cell structure was prepared as follows. That is, a zero-gap type electrolytic cell structure having a cross-sectional structure similar to that of FIG. 1 and an anode chamber 60 in FIG. 1 configured similarly to FIG. 6 was prepared. That is, this electrolytic cell structure has an anode chamber, a cathode chamber, and a gas-liquid separation chamber, and the anode chamber and the cathode chamber are arranged back to back. Also, the baffle plate was provided only in the anode chamber. Specifically, as the baffle plate, a titanium plate with a long side of 866 mm and a short side of 95 mm was used and installed inclined with respect to the anode (inclined so that the angle θ formed by the baffle plate and the anode is 1.27°) as shown in FIG. 8. A dispersion pipe with a diameter of 25.4 mm was installed so as to be parallel to the lower part of the anode chamber (the mounting surface of the electrolytic cell structure). Holes with a diameter of about 1.5 mm were opened in the dispersion pipe at equal intervals. Similarly, a dispersion pipe with a diameter of 12 mm was also installed in the cathode chamber. As the anode, a titanium plate with a thickness of 1 mm was expanded and rolled to 1 mm by roll pressing, and then coated with a coating mainly composed of ruthenium oxide, iridium oxide, and titanium oxide. This anode was attached to the rib. As the cathode, a nickel wire mesh with a wire diameter of 0.15 mm and 40 meshes was used and coated with a coating mainly composed of ruthenium oxide. As the current collector, a nickel plate was expanded and coated with a nickel / nickel oxide coating by a spraying method. A mattress formed by braiding nickel wires with a wire diameter of 0.15 mm was installed as a metal elastic body on the current collector. Further, the above cathode was installed thereon. The cathode was arranged so as to be in contact with the ion exchange membrane. The above-described electrolytic cell structures were arranged in series as shown in Fig. 3, and an electrolytic cell was assembled by sandwiching a cation exchange membrane ACIPLEX (registered trademark) F7001 between adjacent electrolytic cell structures via gaskets. That is, an anode terminal cell with a current lead plate attached to one end and a cathode terminal cell with a current lead plate attached to the other end were arranged, and the electrolytic cell structure and the cation exchange membrane were pressed and connected with a press to assemble the electrolytic cell. The short side length of the electrode was 1500 mm, and the long side length was 2400 mm. Using the above-described electrolytic cell, electrolysis operation was performed under the following conditions. On the anode chamber side of this electrolytic cell, brine with a concentration of 300 g / L was supplied as the anode liquid so that the outlet brine concentration became 205 g / L, and dilute caustic soda was supplied to the cathode chamber side so that the outlet caustic soda concentration became 32% by weight. Electrolysis was carried out at an electrolysis temperature of 85°C, a gauge pressure of 40 kPa during electrolysis, and a current density of 6 kA / m 2 for electrolysis. The measurement results of the power unit, sodium hydroxide production amount, and concentration distribution in the anode chamber (as shown in Fig. 10, the salt concentration was measured at 9 points in the anode chamber, and the difference between the maximum concentration and the minimum concentration was taken as the value of the concentration distribution.) are shown in Table 1.

[0056] [Examples 2 to 8 and Comparative Examples 1 to 4] An electrolytic cell was prepared in the same manner as in Example 1, except that the size of the anode, the size of the frame, the size of the baffle plate, and / or the angle at the time of installing the baffle plate were changed so that the values of L1, L2, L4, V1, L4 / L1, L5 / L1, V1 / V2, and / or θ in Example 1 were as shown in Table 1. Electrolysis operation was performed in the same manner as in Example 1. The measurement results of the power unit, sodium hydroxide production amount, and concentration distribution in the anode chamber are shown in Table 1.

[0057] [Table 1] [Explanation of Symbols]

[0058] 4…Electrolytic cell, 5…Press, 6…Cathode terminal, 7…Anode terminal, 8…Fixed head, 9a…Dummy cell, 9b…Attachment, 11…Anode, 12…Anode gasket, 13…Cathode gasket, 18…Reverse current absorber, 19…Lower part of anode chamber, 21…Cathode, 22…Metal elastic body, 23…Current collector, 24…Support, 50…Electrolytic cell structure, 60…Anode chamber, 51…Ion exchange membrane (diaphragm), 70…Cathode chamber, 80…Partition wall, 101…Frame body, 101a…Bottom surface, 101b…Open part, 101c…Sealing surface, 101d…Virtual surface, 102…Rib, 103…Baffle plate, 104…Gas-liquid separation part (anode-side gas-liquid separation part)

Claims

1. An electrolytic cell structure comprising: a frame body F1 having a bottom surface and an open portion located above the bottom surface; an electrode E1 disposed on the open portion side and having a substantially rectangular shape with a short side L1 (m) × a long side L2 (m); a rib R1 provided on the bottom surface and supporting the electrode E1; a baffle plate B1 fixed to the rib and having a substantially rectangular shape with a short side L3 (m) × a long side L4 (m); and comprising: wherein the short side L1 is 1.3 m or more and 1.6 m or less; an electrolytic cell structure, wherein a ratio of the long side L4 to the short side L1, as L4 / L1, is 0.35 or more and 0.97 or less.

2. further comprising a gas-liquid separation portion having a substantially rectangular parallelepiped shape and separating gas from an electrolytic solution; when a current-carrying surface in the electrolytic cell structure is viewed in plan view, the gas-liquid separation portion has a substantially rectangular shape with a short side L5 (m) × a long side L6 (m); the electrolytic cell structure according to claim 1, wherein a ratio of the short side L5 to the short side L1, as L5 / L1, is 0.03 or more and 0.08 or less.

3. the electrolytic cell structure according to claim 2, wherein a ratio of a volume V1 of a cell compartment defined by the frame body F1 and the electrode E1 to a volume V2 of the gas-liquid separation portion, as V1 / V2, is 15 or more and 20 or less.

4. the electrolytic cell structure according to claim 1, wherein an angle formed by the electrode E1 and the baffle plate B1 is 0.5° or more and 2.4° or less.

5. further comprising an electrode E2 and a conductive mattress pressing a current-carrying surface of the electrode E2; the electrolytic cell structure according to any one of claims 1 to 4, wherein the electrode E1 is an anode and the electrode E2 is a cathode.

6. a plurality of the electrolytic cell structures according to claim 1; an ion exchange membrane disposed between adjacent ones of the electrolytic cell structures; and connecting means configured to connect the electrolytic cell structure and the ion exchange membrane; an electrolytic cell comprising the same.

7. the connecting means comprises a press and a fixed head connected to the press; the electrolytic cell according to claim 6, wherein the fixed head is configured to press an entire surface of a contact surface with the electrolytic cell structure in the electrolytic cell structure by driving of the press.

8. further comprising a dummy cell between the electrolytic cell structure closest to the connecting means and the connecting means; the connecting means comprises a press and a fixed head connected to the press; The fixed head is configured to press the dummy cell by driving the press device. The electrolytic cell according to claim 6, wherein the dummy cell is configured to press the entire surface of the contact surface with the dummy cell in the electrolytic cell structure under the pressing force from the fixed head.

9. The electrolytic cell according to claim 8, wherein the dummy cell is a rigid material.

10. The electrolytic cell further includes an attachment configured to fit into the connecting means. The connecting means includes a press device and a fixed head connected to the press device. The fixed head is configured to be able to press the attachment by driving the press device. The electrolytic cell according to claim 6, wherein the attachment is configured to press the entire surface of the contact surface with the attachment in the electrolytic cell structure under the pressing force from the fixed head.

11. The electrolytic cell according to claim 10, wherein the attachment is a rigid material.

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