Electrolytic cell

Abstract

The electrolytic cell of this invention can prevent the electrolysis voltage from rising and ensure the stable operation of the electrolytic cell. It includes: a cathode frame with a cathode plate fixed to its inner surface; an anode frame with an anode plate fixed to its inner surface; an ion exchange membrane disposed between the cathode frame and the anode frame; a cathode-side fluid supply path for supplying cathode-side fluid to a cathode chamber defined between the cathode frame and the ion exchange membrane; a cathode-side fluid discharge path for discharging cathode-side fluid from the cathode chamber; an anode-side fluid supply path for supplying anode-side fluid to an anode chamber defined between the anode frame and the ion exchange membrane; and an anode-side fluid discharge path for discharging anode-side fluid from the anode chamber. The effective flow path cross-sectional area CD of the cathode-side fluid discharge path is greater than the effective flow path cross-sectional area CS of the cathode-side fluid supply path, and the effective flow path cross-sectional area AD of the anode-side fluid discharge path is greater than the effective flow path cross-sectional area AS of the anode-side fluid supply path.

Description

Technical Field

[0001] The present invention relates to an electrolytic cell, and more particularly, to an electrolytic cell that can be used to produce a quaternary ammonium hydroxide aqueous solution using a quaternary ammonium salt aqueous solution as a raw material, but is not limited thereto. Prior Art

[0002] Patent Documents 1 to 4 below disclose methods for producing quaternary ammonium hydroxide aqueous solutions using quaternary ammonium salt aqueous solutions as raw materials. This production method utilizes an electrolytic cell comprising a cathode frame, a cathode plate secured to the inner surface of the cathode frame, an anode frame, and an anode plate secured to the inner surface of the anode frame. At least one cation exchange membrane is positioned between the cathode plate and the anode plate, defining a cathode chamber between the cathode frame and the cation exchange membrane, and an anode chamber between the anode frame and the cation exchange membrane. Furthermore, a cathode-side fluid supply path for supplying a cathode-side fluid to the cathode chamber and a cathode-side fluid discharge path for discharging the cathode-side fluid from the cathode chamber are provided, as well as an anode-side fluid supply path for supplying an anode-side fluid to the anode chamber and an anode-side fluid discharge path for discharging the anode fluid from the anode chamber. More specifically, the cathode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings spaced apart along the width direction, and a plurality of lower flow paths extending from a plurality of lower openings spaced apart along the width direction. One of the upper flow paths and the lower flow paths constitutes the cathode-side fluid discharge path, and the other of the upper flow paths and the lower flow paths constitutes the cathode-side fluid supply path. Similarly, the anode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings spaced apart along the width direction, and a plurality of lower flow paths extending from a plurality of lower openings spaced apart along the width direction. One of the upper flow paths and the lower flow paths constitutes the anode-side fluid discharge path, and the other of the upper flow paths and the lower flow paths constitutes the anode-side fluid supply path. The cathode side fluid, i.e., the quaternary ammonium hydroxide aqueous solution, circulates through the cathode side fluid supply path, the cathode chamber, and the cathode side fluid discharge path, and the anode side fluid, i.e., the quaternary ammonium salt aqueous solution, circulates through the anode side fluid supply path, the anode chamber, and the anode side fluid discharge path. [Prior Art Literature] [Patent Document]

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 62-142792 Patent Document 2: Japanese Patent Publication No. 8-16274 Patent Document 3: Japanese Patent Publication No. 8-19539 Patent Document 4: Japanese Patent Application Laid-Open No. 2009-13477 Summary of the Invention

[0004] [Problems to be solved by the invention]

[0005] Furthermore, in the above-mentioned electrolytic cell, the effective flow path cross-sectional area of ​​the cathode side fluid supply path and the effective flow path cross-sectional area of ​​the cathode side fluid discharge path are set to be substantially the same, and the effective flow path cross-sectional area of ​​the anode side fluid supply path and the effective flow path cross-sectional area of ​​the anode side fluid discharge path are set to be substantially the same. Furthermore, in particular, in Japanese Patent Application No. 2022-33651, in the electrolytic cell proposed by the inventors of the present case (i.e., at least one upper through-opening matching the upper opening of the cathode frame is formed at the upper end of the cathode plate, and at least one lower through-opening matching the lower opening of the cathode frame is formed at the lower end of the cathode plate, at least one upper through-opening matching the upper opening of the anode frame is formed at the upper end of the anode plate, and at least one lower through-opening matching the lower opening of the anode frame is formed at the lower end of the anode plate, and the upper through-opening and lower through-opening formed in the cathode plate, and the upper through-opening and lower through-opening formed in the anode plate define an effective flow path cross-sectional area of ​​the fluid flow path), in order to achieve maximum electric field efficiency, the effective flow path area is set to the necessary minimum. However, the inventors of this case, after repeated research and experiments on the operation of the electrolytic cell, discovered that gas is generated in the cathode chamber and the anode chamber due to electrolysis. In addition to the cathode side fluid and the anode side fluid, the generated gas also flows in the cathode side fluid discharge path and the anode side fluid discharge path. This causes the flow rate in the cathode side fluid discharge path and the anode side fluid discharge path to increase compared to the cathode side fluid supply path and the anode side fluid supply path, thereby generating back pressure, which causes the electrolysis voltage to increase and tends to hinder the stable operation of the electrolytic cell.

[0006] The present invention is completed in view of the above facts. The main technical problem is to provide a new and improved electrolytic cell to avoid the increase of electrolysis voltage and ensure the stable operation of the electrolytic cell. [Methods to solve the problem]

[0007] Based on the above facts recognized by the inventors of this case, they discovered that the above main technical issues can be achieved by making the effective flow path cross-sectional area CD of the cathode side fluid discharge path larger than the effective flow path cross-sectional area CS of the cathode side fluid supply path, and making the effective flow path cross-sectional area AD of the anode side fluid discharge path larger than the effective flow path cross-sectional area AS of the anode side fluid supply path.

[0008] That is, the present invention provides an electrolytic cell capable of achieving the above-mentioned main technical problems, comprising: A cathode frame, on the inner surface of which the cathode plate is fixed; Anode frame, on the inner surface of which the anode plate is fixed; An ion exchange membrane is provided between the cathode frame and the anode frame; a cathode side fluid supply path for supplying cathode side fluid to the cathode chamber defined between the cathode frame and the ion exchange membrane; a cathode side fluid discharge path for discharging the cathode side fluid from the cathode chamber; an anode side fluid supply path for supplying anode side fluid to the anode chamber defined between the anode frame and the ion exchange membrane; and an anode side fluid discharge path for discharging the anode side fluid from the anode chamber; The effective flow path cross-sectional area CD of the cathode side fluid discharge path is larger than the effective flow path cross-sectional area CS of the cathode side fluid supply path; The effective flow path cross-sectional area AD of the anode side fluid discharge path is larger than the effective flow path cross-sectional area AS of the anode side fluid supply path.

[0009] The effective flow path cross-sectional area CD is 1.1 to 3.0 times the effective flow path cross-sectional area CS (CD=1.1 to 3.0CS), and the effective flow path cross-sectional area AD is 1.1 to 3.0 times the effective flow path cross-sectional area AS (AD=1.1 to 3.0AS). It is particularly preferred that the effective flow path cross-sectional area CD is 1.5 to 2.5 times the effective flow path cross-sectional area CS (CD=1.5 to 2.5CS), and the effective flow path cross-sectional area AD is 1.5 to 2.5 times the effective flow path cross-sectional area AS (AD=1.5 to 2.5AS).

[0010] In a preferred embodiment, The cathode frame is provided with at least one upper flow path extending from an upper opening at an upper end portion of the inner surface and at least one lower flow path extending from a lower opening at a lower end portion of the inner surface; The anode frame is provided with at least one upper flow path extending from an upper opening at an upper end portion of the inner surface and at least one lower flow path extending from a lower opening at a lower end portion of the inner surface; The cathode plate extends continuously from above the upper opening of the cathode frame to below the lower opening of the cathode frame; At least one upper through opening is formed at the upper end of the cathode plate to match the upper opening of the cathode frame, and at least one lower through opening is formed at the lower end of the cathode plate to match the lower opening of the cathode frame; The anode plate extends continuously from above the upper opening of the anode frame to below the lower opening of the anode frame; At least one upper through-opening is formed at the upper end of the anode plate to match the upper opening of the anode frame, and at least one lower through-opening is formed at the lower end of the anode plate to match the lower opening of the anode frame; The upper through-opening of the cathode plate and the upper flow path of the cathode frame constitute one of the cathode-side fluid discharge path and the cathode-side fluid supply path, and the lower through-opening of the cathode plate and the lower flow path of the cathode frame constitute the other of the cathode-side fluid discharge path and the cathode-side fluid supply path; The upper through-opening of the anode plate and the upper flow path of the anode frame constitute one of the anode side fluid discharge path and the anode side fluid supply path, and the lower through-opening of the anode plate and the lower flow path of the anode frame constitute the other of the anode side fluid discharge path and the anode side fluid supply path.

[0011] The better aspect is: The cathode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings spaced apart along the width direction at an upper end portion of the inner surface, and a plurality of lower flow paths extending from a plurality of lower openings spaced apart along the width direction at a lower end portion of the inner surface; The anode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings spaced apart along the width direction at an upper end portion of the inner surface, and a plurality of lower flow paths extending from a plurality of lower openings spaced apart along the width direction at a lower end portion of the inner surface; A plurality of upper through openings are formed at the upper end of the cathode plate, each of which matches the plurality of upper openings of the cathode frame; and a plurality of lower through openings are formed at the lower end of the cathode plate, each of which matches the plurality of lower openings of the cathode frame. A plurality of upper through-openings are formed at the upper end of the anode plate, each of which matches the plurality of upper openings of the anode frame; and a plurality of lower through-openings are formed at the lower end of the anode plate, each of which matches the plurality of lower openings of the anode frame. The number of the upper through-openings of the cathode plate and the upper flow path of the cathode frame, or the lower through-openings of the cathode plate and the lower flow path of the cathode frame, constituting the cathode-side fluid discharge path, is greater than the number of the lower through-openings of the cathode plate and the lower flow path of the cathode frame, or the upper through-openings of the cathode plate and the upper flow path of the cathode frame, constituting the cathode-side fluid supply path; The number of the upper through-opening of the anode plate and the upper flow path of the anode frame, or the lower through-opening of the anode plate and the lower flow path of the anode frame, constituting the anode-side fluid discharge path, is greater than the number of the lower through-opening of the anode plate and the lower flow path of the anode frame, or the upper through-opening of the anode plate and the upper flow path of the anode frame, constituting the anode-side fluid supply path.

[0012] The upper opening and lower opening of the cathode frame, as well as the upper through-opening and lower through-opening of the cathode plate, preferably have a circular cross-sectional shape. The upper opening and lower opening of the anode frame, as well as the upper through-opening and lower through-opening of the anode plate, preferably have a circular cross-sectional shape. The cathode plate and the anode plate are preferably formed of rectangular plates.

[0013] In a preferred embodiment of the present invention, at least one cation exchange membrane is disposed between the cathode plate and the anode plate in the electrolytic cell, and the electrolytic cell is used to produce a quaternary ammonium hydroxide aqueous solution using a quaternary ammonium salt aqueous solution as a raw material. [Effects of the Invention]

[0014] In the electrolytic cell of the present invention, the effective flow path cross-sectional area CD of the cathode side fluid discharge path is larger than the effective flow path cross-sectional area CS of the cathode side fluid supply path, and the effective flow path cross-sectional area AD of the anode side fluid discharge path is larger than the effective flow path cross-sectional area AS of the anode side fluid supply path. Therefore, the electrolysis voltage can be avoided from rising and the stable operation of the electrolytic cell can be ensured. This can be clearly understood from the embodiments described below. Simple diagram description

[0015] FIG1 is a schematic cross-sectional view showing a preferred embodiment of an electrolytic cell according to the present invention. FIG2 is a schematic cross-sectional view taken along line II-II of FIG1 showing the cathode frame and cathode plate in the electrolytic cell shown in FIG1. 3 is a partially enlarged cross-sectional view showing the upper opening of the cathode frame, the through opening formed on the upper side of the cathode plate, and the communicating opening formed on the upper side of the sealing gasket in the electrolytic cell shown in FIG. 1 . FIG4 is a schematic cross-sectional view showing the cathode frame and cathode plate of a modified example of the electrolytic cell constructed according to the present invention, which are the same parts as FIG2 . Implementation Method

[0016] Hereinafter, a more detailed description will be given with reference to the accompanying drawings showing preferred embodiments of the electrolytic cell according to the present invention.

[0017] 1 and 2 , the electrolytic cell according to the present invention includes a hollow rectangular parallelepiped housing 2, which is composed of a cathode frame 4 ( FIG. 1 ), an anode frame 6 ( FIG. 1 ), a cathode upper wall member 8, an anode upper wall member 10, a cathode lower wall member 12, an anode lower wall member 14, a cathode front wall member 16 ( FIG. 2 ), an anode front wall member (not shown), a cathode rear wall member 18 ( FIG. 2 ), and an anode rear wall member (not shown). The cathode frame 4, anode frame 6, cathode front wall member 16, anode front wall member, cathode rear wall member 18, and anode rear wall member extend substantially vertically, while the cathode upper wall member 8, anode upper wall member 10, cathode lower wall member 12, and anode lower wall member 14 extend substantially horizontally. The base end surface (right end surface in FIG. 1 ) of the cathode-side upper wall member 8 is connected to the upper edge of the inner surface of the cathode frame 4 via appropriate fastening means such as screws or adhesives. The base end surface (right end surface in FIG. 1 ) of the cathode-side lower wall member 12 is connected to the lower edge of the inner surface of the cathode frame 4 via appropriate fastening means. Similarly, the base end surface (left end surface in FIG. 1 ) of the anode-side upper wall member 10 is connected to the upper edge of the inner surface of the anode frame 6 via appropriate fastening means. The base end surface (left end surface in FIG. 1 ) of the anode-side lower wall member 14 is connected to the lower edge of the inner surface of the anode frame 6 via appropriate fastening means. The cathode-side front wall member 16 is connected to the front face of the cathode frame 4 via appropriate connecting means, the anode-side front wall member is connected to the front face of the anode frame 6 via appropriate connecting means, the cathode-side rear wall member 18 is connected to the rear face of the cathode frame 4 via appropriate connecting means, and the anode-side rear wall member is connected to the rear face of the anode frame 6 via appropriate connecting means. The cathode-side and anode-side upper wall members 8 and 10, lower wall members 12 and 14, and front wall member 16 and rear wall member 18, respectively, may be pre-formed integrally and then connected to the cathode frame 4 or anode frame 6, instead of being connected to the cathode frame 4 or anode frame 6 in the above manner. Alternatively, the wall portions may be integrally formed with the cathode frame 4 or anode frame 6. Furthermore, when the upper wall members 8 and 10, lower wall members 12 and 14, and front wall member 16 and rear wall member 18 are integrally formed, a sealing member may be inserted into and secured to the cathode frame 4 or anode frame 6. As a sealing member, the sealing gasket 38, described later, can be extended from the dimensions corresponding to the cathode plate 32 or anode plate 56 to the dimensions corresponding to the cathode frame 4 or anode frame 6, and the extended portion can be utilized. The cathode frame 4, anode frame 6, cathode-side upper wall member 8, anode-side upper wall member 10, cathode-side lower wall member 12, anode-side lower wall member 14, cathode-side front wall member 16, anode-side front wall member, cathode-side rear wall member 18, and anode-side rear wall member, excluding the openings and flow paths described later, can be in the form of solid blocks or plates and can be formed from suitable synthetic resins such as olefin resins such as polypropylene and polyethylene, vinyl chloride resins, and fluorine-based resins.Appropriate sealing members (not shown) such as gaskets may be interposed between the interconnected portions of the cathode frame 4, anode frame 6, cathode upper wall member 8, anode upper wall member 10, cathode lower wall member 12, anode lower wall member 14, cathode front wall member 16, anode front wall member, cathode rear wall member 18, and anode rear wall member.

[0018] Continuing with reference to FIG1 , FIG2 and FIG3 , a plurality of (six in the figure) upper openings 20 (one of which is shown by a dotted line and a solid line in FIG1 and FIG3 , respectively) are formed at equal intervals along the width direction (the direction perpendicular to the paper in FIG1 and the left-right direction in FIG2 ) at the upper end portion of the inner surface of the cathode frame 4 (the left side in FIG1 ), and a plurality of (six in the figure) upper flow paths 22 (one of which is shown by a dotted line and a solid line in FIG1 and FIG3 , respectively) are formed in the cathode frame 4 so as to extend substantially horizontally from each of the upper openings 20 through the cathode frame 4. Similarly, a plurality (three in the figure) of lower openings 24 (one of which is shown by a dotted line in FIG1 ) are formed at equal intervals along the width direction (a direction perpendicular to the paper in FIG1 , a horizontal direction in FIG2 ) at the lower end of the inner surface of the cathode frame 4 (the left side in FIG1 ). Furthermore, a plurality (three in the figure) of lower flow paths 26 (one of which is shown by a dotted line in FIG1 ) are formed in the cathode frame 4 , extending substantially horizontally from each lower opening 24 through the cathode frame 4 . The upper opening 20 and the lower opening 24 can be circular, and the cross-sectional shapes of the upper flow path 22 and the lower flow path 26 can be circular, corresponding to the circular shapes of the upper opening 20 and the lower opening 24 . The upstream flow path 22 and the downstream flow path 26 are connected through an external flow path (not shown) arranged on the outside of the outer shell 2. A circulation pump, a product storage tank and multiple valve components for flow control are also arranged on the external flow path 31 (a part of which is shown in Figure 2) (the external flow path and the above-mentioned components arranged thereon are well known, so detailed description is omitted in this manual).

[0019] A cathode plate 32 is fixed to the inner surface of the cathode frame 4. In the illustrated embodiment, the cathode plate 32 extends continuously from above the upper opening 20 formed in the cathode frame 4 to below the lower opening 24 formed in the cathode frame 4. The cathode plate 32 is formed of a rectangular plate made of a suitable conductive metal such as nickel. Its upper end surface contacts or is adjacent to the inner surface (i.e., bottom surface) of the cathode-side upper wall member 8, its lower end surface contacts or is adjacent to the inner surface (i.e., top surface) of the cathode-side lower wall member 12, its front side surface contacts or is adjacent to the inner surface (i.e., back surface) of the front wall member 16, and its rear side surface contacts or is adjacent to the inner surface (i.e., front surface) of the rear wall member 18. The cathode plate 32 can be secured to the cathode frame 4 by, for example, inserting locking screws (not shown) through the cathode plate 32 at the four corners and screwing them into the cathode frame 4. A plurality of upper through-openings 34 (six shown) are formed at equal intervals along the width direction (the direction perpendicular to the paper in FIG. 1 and the left-right direction in FIG. 2 ) at the upper end of the cathode plate 32. A plurality of lower through-openings 36 (three shown) are formed at equal intervals along the width direction (the direction perpendicular to the paper in FIG. 1 and the left-right direction in FIG. 2 ) at the lower end of the cathode plate 32 (the upper through-openings 34 and the lower through-openings 36 will be described later). Each upper through-opening 34 formed in the cathode plate 32 is located at a position that matches each of the upper openings 20 formed in the upper end of the cathode frame 4. In the illustrated embodiment, each upper through-opening 34 and each of the upper openings 20 have the same shape (circular) and the same size. Similarly, it is also important that each lower through-opening 36 formed in the cathode plate 32 is located at a position that matches each of the lower openings 24 formed in the lower end of the cathode frame 4. In the illustrated embodiment, each lower through-opening 36 has the same shape (circular) and the same size as each lower opening 24. The upper through-opening 34 (and the upper opening 20) are preferably located near the upper end of the cathode plate 32, while the lower through-opening 36 (and the lower opening 24) are preferably located near the lower end of the cathode plate 32.

[0020] Continuing with reference to Figures 1 and 3 , it is preferred to insert a sealing gasket 38 between the cathode frame 4 and the cathode plate 32. The sealing gasket 38 stably secures the cathode plate 32 to the cathode frame 4 and prevents liquid from penetrating the interface between the cathode frame 4 and the cathode plate 32, causing corrosion. The sealing gasket 38 can be a rectangular plate of substantially the same size as the cathode plate 32 (or, as described above, the sealing gasket 38 can be sized to correspond to the size of the cathode frame 4) and formed from a suitable elastomer, such as silicone rubber, ethylene propylene rubber, chloroprene rubber, soft vinyl chloride, butyl rubber, butadiene rubber, or fluororubber. With the sealing gasket 38 inserted between the cathode frame 4 and the cathode plate 32, locking screws (not shown) can be inserted through the cathode plate 32 and the sealing gasket 38 at the four corners of the cathode plate 32 and screwed to the cathode frame 4. A plurality of upper communicating openings 40 (six in the figure) are formed at the upper end of the sealing gasket 38, communicating with each upper through-opening 34 formed in the cathode plate 32 and each upper opening 20 formed in the cathode frame 4. A plurality of lower communicating openings 42 (three in the figure) are formed at the lower end of the sealing gasket 38, communicating with each lower through-opening 36 formed in the cathode plate 32 and each lower opening 24 formed in the cathode frame 4. As can be clearly understood with reference to FIG3 , the upper communicating openings 40 and the lower communicating openings 42 formed in the sealing gasket 38 are preferably larger than the upper through-opening 34 and the upper opening 20, and the lower through-opening 36 and the lower opening 24. If the upper and lower communication openings 40, 42 formed in the sealing gasket 38 are substantially the same size as the upper through-opening 34, upper opening 20, and lower through-opening 36, lower opening 24, then if the electrolytic cell is operated continuously, the sealing gasket 38 will slightly expand, causing the upper and lower communication openings 40, 42 to shrink and shift, potentially leading to inadequate or damaged communication between the upper through-opening 34 and upper opening 20, and between the lower through-opening 36 and lower opening 24. The upper and lower communication openings 40, 42 can be circular, having a diameter that is a predetermined length greater than the diameters of the upper through-opening 34, upper opening 20, and lower through-opening 36, 24. Each upper communication opening 40 and each lower communication opening 42 does not need to be concentric with the upper through-opening 34 and upper opening 20, and the lower through-opening 36 and lower opening 24, respectively; they may be eccentric. The diameters of the upper communication openings 40 and lower communication openings 42, as well as the degree of eccentricity relative to the upper through-opening 34 and upper opening 20, and the lower through-opening 36 and lower opening 24, can be determined through experimentation based on the expansion and displacement of the sealing gasket 38 during continuous operation of the electrolytic cell. The larger the upper communication openings 40 and lower communication openings 42 formed on the sealing gasket 38, the lower the likelihood of insufficient connectivity or damage. However, as will be described later, the increased area of ​​liquid contacting the back surface of the cathode plate 32 can cause galvanic corrosion, leading to increased mixing of electrode metal into the liquid.Therefore, the preferred dimensions of the upper communication opening 40 and lower communication opening 42 formed in the sealing gasket 38 are the dimensions of the upper through-opening 34 and upper opening 20, and the lower through-opening 36 and lower opening 24, plus 30 mm or less, preferably plus 20 mm or less, and even more preferably plus 10 mm or less. Furthermore, when the sealing gasket 38 is made of a material that does not readily expand, even if the dimensions of the upper communication opening 40 and lower communication opening 42 are close to the dimensions of the upper through-opening 34 and upper opening 20, and the lower through-opening 36 and lower opening 24, the likelihood of insufficient communication or damage is reduced. Therefore, the linear expansion coefficient of the material used for the sealing gasket 38 is preferably 3×10⁻4 (1 / °C) or less, more preferably 1.5×10⁻4 (1 / °C) or less, and most preferably 1×10⁻4 (1 / °C) or less.

[0021] In the illustrated embodiment, the anode frame 6 is substantially identical to the cathode frame 4 described above. Specifically, the cathode frame 4 and the anode frame 6 are symmetrical about an imaginary plane extending perpendicular to the paper in FIG. 1 . Consequently, the anode frame 6 is provided with an upper opening 44, an upper flow path 46, a lower opening 48, and a lower flow path 50. To avoid duplication, detailed descriptions of the upper opening 44, upper flow path 46, lower opening 48, and lower flow path 50 are omitted. The upper flow path 46 and the lower flow path 50 are connected via an external flow path (not shown) disposed outside the housing 2. The external flow path also houses a circulation pump, a raw material storage tank, and multiple valve components for flow control. (The external flow path and the components disposed thereon are well known, so detailed descriptions are omitted in this specification.)

[0022] An anode plate 56 is fixed to the inner surface of the anode frame 6. In the illustrated embodiment, the anode plate 56 is substantially identical to the cathode plate 32 described above, except that it is formed of a suitable conductive metal suitable for use as an anode, such as titanium plated with indium oxide. More specifically, the cathode plate 32 and the anode plate 56 are plane-symmetrical about an imaginary plane extending perpendicular to the paper in FIG. 1 . Thus, the anode plate 56 is rectangular and extends continuously from above the upper opening 44 formed in the anode frame 6 to below the lower opening 48 formed in the anode frame 6. Furthermore, the anode plate 56 includes an upper through-opening 58 and a lower through-opening 60, respectively, located at positions corresponding to the upper opening 44 and lower opening 48 formed in the anode frame 6. To avoid duplication, a detailed description of the anode plate 56 is omitted.

[0023] In the illustrated embodiment, a sealing gasket 62 is also interposed between the anode frame 6 and the anode plate 56. This sealing gasket 62 is substantially identical to the sealing gasket 38 interposed between the cathode frame 4 and the cathode plate 32. More specifically, the sealing gasket 38 and the sealing gasket 62 are symmetrical about an imaginary plane extending perpendicular to the paper in FIG. 1 . Consequently, the sealing gasket 62 forms an upper connecting opening 64 that connects the upper opening 44 formed in the anode frame 6 with the upper through-opening 58 formed in the anode plate 56, and a lower connecting opening 66 that connects the lower opening 48 formed in the anode frame 6 with the lower through-opening 60 formed in the anode plate 56. To avoid duplication, detailed descriptions of the sealing gasket 62, the upper connecting opening 64, and the lower connecting opening 66 are omitted.

[0024] As can be clearly understood with reference to FIG1 , in the illustrated embodiment, a cation exchange membrane 68 is disposed between the cathode plate 32 and the anode plate 56. This membrane can be of conventional configuration. The cation exchange membrane 68 is rectangular in shape, with its upper edge sandwiched between the cathode-side upper wall member 8 and the anode-side upper wall member 10 , and its lower edge sandwiched between the cathode-side lower wall member 12 and the anode-side lower wall member 14 . The front edges of the cathode frame 4 and the anode frame 6 are sandwiched between the cathode-side front wall member 16 and the anode-side front wall member, and the back edges of the cathode frame 4 and the anode frame 6 are sandwiched between the cathode-side rear wall member 18 and the anode-side rear wall member. Appropriate sealing members (not shown) may be inserted between the cation exchange membrane 68 and the cathode side upper wall member 8 and the anode side upper wall member 10, between the cation exchange membrane 68 and the cathode side lower wall member 12 and the anode side lower wall member 14, between the cathode side front wall member 16 and the anode side front wall member, and between the cathode side rear wall member 18 and the anode side rear wall member.

[0025] In the electrolytic cell described above, a cathode chamber or product chamber 70 is defined between the cathode plate 32 and the cation exchange membrane 68, and an anode chamber or feed chamber 72 is defined between the anode plate 56 and the cation exchange membrane 68. Furthermore, a diluted aqueous solution of quaternary ammonium hydroxide (or pure water) circulates through the product chamber 70. More specifically, it flows into the product chamber 70 through one of the lower flow path 26 and upper flow path 22 formed in the cathode frame 4 and flows out of the product chamber 70 through the other. Simultaneously, an aqueous solution of a quaternary ammonium salt circulates through the feed chamber 72. More specifically, it flows into the feed chamber 72 through one of the lower flow path 50 and upper flow path 46 formed in the anode frame 6 and flows out through the other. An electrolysis voltage is applied between the cathode plate 32 and the anode plate 56. Consequently, the concentration of the aqueous solution of quaternary ammonium hydroxide circulating in the product chamber 70 gradually increases. This electrolysis process is well known, and therefore a detailed description thereof will be omitted in this specification. Furthermore, in the illustrated embodiment of the electrolytic cell constructed according to the present invention, the cathode plate 32 and the anode plate 56 extend continuously from above the upper openings 20 and 44 formed in the cathode frame 4 and the anode frame 6 to below the lower openings 24 and 48, respectively. Upper through-openings 34 and 58 and lower through-openings 36 and 60 are formed in the cathode plate 32 and the anode plate 56, respectively, to match the upper openings 20 and 44 and the lower openings 24 and 48. Therefore, the cathode plate 32 and the anode plate 56 extend in a manner that substantially covers the entire interior surface of the cathode frame 4 and the anode frame 6, respectively. Consequently, the cathode plate 32 and the anode plate 56 have a relatively large current-carrying area relative to the size of the electrolytic cell, thereby enabling electrolysis to proceed smoothly through improved electrolysis efficiency.

[0026] In the electrolytic cell constructed according to the present invention, it is important to ensure that the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is greater than the effective flow path cross-sectional area CS of the cathode-side fluid supply path, and that the effective flow path cross-sectional area AD of the anode-side fluid discharge path is greater than the effective flow path cross-sectional area AS of the anode-side fluid supply path. The term "effective flow path cross-sectional area" refers to the minimum cross-sectional area of ​​a flow path. In the illustrated embodiment, the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is defined by the six upper through-openings 34 formed in the cathode plate 32, the upper communication openings 40 connected to the upper through-openings 34, the upper openings 20, the upper flow path 22, and a portion of the outer flow path 31. The cross-sectional areas of the upper communication openings 34, the upper openings 20, the upper flow path 22, and a portion of the outer flow path 31 are equal to or greater than the cross-sectional area of ​​the upper through-openings 34. Therefore, the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is defined by the combined cross-sectional area of ​​the six upper through-openings 34. Furthermore, the effective flow path cross-sectional area CS of the cathode-side fluid supply path is defined by the three lower through-openings 36 formed in the cathode plate 32, the lower communication opening 42 connected to the lower through-opening 36, the lower opening 24, the lower flow path 26, and a portion of the outer flow path 31. The cross-sectional areas of the lower communication opening 42, the lower opening 24, the lower flow path 26, and a portion of the outer flow path 31 are equal to or larger than the cross-sectional area of ​​the lower through-opening 36. Thus, the effective flow path cross-sectional area CS of the cathode-side fluid supply path is defined by the combined cross-sectional area of ​​the three lower through-openings 36. In particular, from the perspective of suppressing an increase in back pressure caused by the discharged fluid, the cross-sectional area of ​​a portion of the outer flow path 31 is preferably larger than the cross-sectional areas of the upper through-opening 34 and the lower through-opening 36. Specifically, the cross-sectional area of ​​a portion of the outer flow path 31 is preferably at least 1.0 times, and more preferably at least 1.5 times, the cross-sectional area of ​​the upper through-opening 34 and the lower through-opening 36. The cross-sectional area of ​​a portion of the outer flow path 31 relative to the cross-sectional area of ​​the upper through-opening 34 and the lower through-opening 36 can be appropriately determined in consideration of the effective flow path cross-sectional area and the amount of fluid supplied.

[0027] In the illustrated embodiment, as described above, six upper through-openings 34 are formed at equal intervals along the width direction (the direction perpendicular to the paper in FIG. 1 and the left-right direction in FIG. 2 ). Conversely, three lower through-openings 36 are formed at equal intervals along the width direction (the direction perpendicular to the paper in FIG. 1 and the left-right direction in FIG. 2 ). The cross-sectional area of ​​each of the six upper through-openings 34 is identical to the cross-sectional area of ​​each of the three lower through-openings 36. Consequently, the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is twice the effective flow path cross-sectional area CS of the cathode-side fluid supply path. As will be understood from the embodiments described below, the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is preferably 1.1 to 3.0 times (CD = 1.1 to 3.0 CS), and more preferably 1.5 to 2.5 times (CD = 1.5 to 2.5 CS), of the effective flow path cross-sectional area CS of the cathode-side fluid supply path.

[0028] The cross-sectional areas of the upper through-openings 34 and lower through-openings 36 formed in the cathode plate 32 are preferably set to the minimum required values ​​to achieve maximum electric field efficiency. However, the inventors of this invention, through repeated research and experimentation on the operation of the electrolytic cell, discovered that gas is generated by electrolysis in the cathode chamber, or product chamber 70, and that this generated gas flows in the cathode-side fluid discharge path in addition to the cathode-side fluid. Therefore, if the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is set to be the same as the effective flow path cross-sectional area CS of the cathode-side fluid supply path, the flow rate in the cathode-side fluid discharge path increases compared to the cathode-side fluid supply path, generating back pressure. This tends to increase the electrolysis voltage and hinder the stable operation of the electrolytic cell. However, in the electrolytic cell constructed according to the present invention, the effective flow path cross-sectional area CD of the cathode side fluid discharge path is set to be larger than the effective flow path cross-sectional area CS of the cathode side fluid supply path, so that the electrolysis voltage can be avoided from rising and the stable operation of the electrolytic cell can be ensured. This can also be clearly understood from the embodiments described below.

[0029] In the above-mentioned embodiments illustrated in Figures 1 to 3, the number of upper through-openings 34 (6) is greater than the number of lower through-openings 36 (3), so that the effective flow path cross-sectional area CD of the cathode side fluid discharge path is larger than the effective flow path cross-sectional area CS of the cathode side fluid supply path. However, the number of upper through-openings 34 and the number of lower through-openings 36 can be set to be the same as needed, and the respective cross-sectional area of ​​the upper through-openings 34 can be set to be larger than the respective cross-sectional area of ​​the lower through-openings 36, so that the effective flow path cross-sectional area CD of the cathode side fluid discharge path is larger than the effective flow path cross-sectional area CS of the cathode side fluid supply path. In the modified example illustrated in FIG4 , three upper through-openings 34 are formed at equal intervals along the width direction (the horizontal direction in FIG4 ) at the upper end of the cathode plate 32 (thus, three upper communication openings 40, three upper openings 20, and three upper flow paths 22 are also formed). Three lower through-openings 36 are formed at equal intervals along the width direction (the horizontal direction in FIG4 ) at the lower end of the cathode plate 32. The cross-sectional area of ​​each upper through-opening 34 is set to twice the cross-sectional area of ​​each lower through-opening 36. However, according to the experience of the present inventors, having more upper through-openings 34 than lower through-openings 36 tends to smooth the discharge flow, compared to setting the cross-sectional area of ​​each upper through-opening 34 larger than the cross-sectional area of ​​each lower through-opening 36.

[0030] In the above-mentioned embodiments and variations, a plurality of upper through openings 34 and lower through openings 36 are formed at equal intervals along the width direction of the cathode plate 32. However, as needed, one upper through opening and one lower through opening extending slenderly along the width direction may be formed on the cathode plate 32, and the cross-sectional area of ​​the upper through opening 34 may be larger than the cross-sectional area of ​​the lower through opening 36.

[0031] Furthermore, in the above-mentioned embodiment and modification, the cathode plate 32 is formed to continuously extend from above the upper opening 20 formed in the cathode frame 4 to below the lower opening 24 formed in the cathode frame 4, and a plurality of upper through openings 34 are formed at equal intervals along the width direction (the direction perpendicular to the paper in FIG. 1 and the left-right direction in FIG. 2 and FIG. 4) at the upper end portion of the cathode plate 32, and a plurality of upper through openings 34 are formed at equal intervals along the width direction (the direction perpendicular to the paper in FIG. 1 and the left-right direction in FIG. 2 and FIG. 4) at the lower end portion of the cathode plate 32. A plurality of lower through-openings 36 are formed at intervals. However, if necessary, for example, the cathode plate 32 may be configured to extend from below the upper opening 20 formed in the cathode frame 4 to above the lower opening 24 formed in the cathode frame 4, with the upper opening 20 formed in the cathode frame 4 defining the upstream end of the cathode-side fluid discharge path and the lower opening 24 formed in the cathode frame 4 defining the downstream end of the cathode-side fluid supply path, without forming the upper through-openings 34 and the lower through-openings 36 in the cathode plate 32. In this case, the effective flow path cross-sectional area of ​​the cathode-side fluid discharge path is defined by the total cross-sectional area of ​​the upper openings 20, and the effective flow path cross-sectional area of ​​the cathode-side fluid supply path is defined by the total cross-sectional area of ​​the lower openings 24.

[0032] The above specifically describes the relationship between the effective flow path cross-sectional area CD of the cathode side fluid discharge path and the effective flow path cross-sectional area CS of the cathode side fluid supply path, while the relationship between the effective flow path cross-sectional area AD of the anode side fluid discharge path and the effective flow path cross-sectional area AS of the anode side fluid supply path is exactly the same. In order to avoid duplication of explanation, the specific description of the relationship between the effective flow path cross-sectional area AD of the anode side fluid discharge path and the effective flow path cross-sectional area AS of the anode side fluid supply path is omitted.

[0033] Examples 1 to 3 and Comparative Example 1 An electrolytic cell of the configuration shown in Figures 1 to 3 or 4 was fabricated and operated in a constant current control mode. The average cell voltage (the voltage between the anode and cathode plates) during the operation period was measured. In Examples 1 to 3, the effective flow path cross-sectional area CD of the cathode-side fluid discharge path was greater than the effective flow path cross-sectional area CS of the cathode-side fluid supply path. Similarly, the effective flow path cross-sectional area AD of the anode-side fluid discharge path was greater than the effective flow path cross-sectional area AS of the anode-side fluid supply path. On the other hand, in Comparative Example 1, the effective flow path cross-sectional area CD of the cathode-side fluid discharge path was equal to the effective flow path cross-sectional area CS of the cathode-side fluid supply path. Similarly, the effective flow path cross-sectional area AD of the anode-side fluid discharge path was equal to the effective flow path cross-sectional area AS of the anode-side fluid supply path. The average cell voltage values ​​are shown in Table 1.

[0034] The details of the components and operating status of the electrolytic cell are as follows. Operation time: 30 days Cathode: Nickel plate (thickness 2mm, surface size 1m×1m) Anode: Titanium plate with indium oxide electroplated on the surface (thickness 2mm, surface size 1m×1m) Cation exchange membrane: N324 sold by Chemours Company (thickness 1mm) Sealing gasket: EPDM (the diameters of the upper and lower connecting openings are 2mm larger than the diameters of the corresponding upper and lower through-openings, respectively) Raw material (anode side fluid): methylammonium chloride aqueous solution Product (cathode side fluid): methylammonium hydroxide aqueous solution Current: 1000A (10A / dm2) Operating temperature: 70℃ Electrolyzer assembly temperature: 20°C Raw material (anode side fluid) flow rate: 20L / min Product (cathode side fluid) flow rate: 20L / min

[0035] [Table 1] Upper through opening (discharge path) Lower through opening (supply path) Battery voltage (V) Number of openings (indivual) Opening diameter (mm) Number of openings (indivual) Opening diameter (mm) Example 1 12 10 10 10 8.9 Example 2 20 10 10 10 8.4 Example 3 10 16 10 10 8.6 Comparative Example 1 10 10 10 10 9.8

[0036] While the present invention has been described in detail above with reference to the accompanying drawings illustrating preferred embodiments, the present invention is not limited to these embodiments and, needless to say, various modifications and variations are possible without departing from the technical scope of the present invention. For example, in the illustrated embodiment, a single cation exchange membrane 68 is disposed between the cathode plate 32 and the anode plate 56. However, the present invention is also applicable to electrolytic cells in which multiple exchange membranes (cation exchange membranes and anion exchange membranes) are disposed between the cathode plate 32 and the anode plate 56.

[0037] 2: Shell 4: Cathode frame 6: Anode frame 8: Cathode side upper wall component 10: Anode side upper wall component 12: cathode side lower wall component 14: Anode side lower wall component 16: cathode side front wall component 18: cathode side rear wall component 20: Upper side opening 22: Upper flow path 24: Lower side opening 26: Lower flow path 31: Outer flow path 32: cathode plate 34: Upper through opening 36: Bottom through opening 38:Sealing pad 40: Upper side connecting opening 42: Lower side communication opening 44: Upper side opening 46: Upper flow path 48: Lower side opening 50: Lower flow path 56: Anode plate 58: Upper through opening 60: Bottom through opening 62:Sealing pad 64: Upper side connecting opening 66: Lower side connecting opening 68: Cation exchange membrane 70: Product room (cathode room) 72: Raw material room (anode room)

Claims

1. An electrolytic cell comprising: a cathode frame with a cathode plate fixed on its inner surface; an anode frame with an anode plate fixed on its inner surface; an ion exchange membrane disposed between the cathode frame and the anode frame; a cathode-side fluid supply path for supplying cathode-side fluid to a cathode chamber defined between the cathode frame and the ion exchange membrane; a cathode-side fluid discharge path for discharging cathode-side fluid from the cathode chamber; an anode-side fluid supply path for supplying anode-side fluid to an anode chamber defined between the anode frame and the ion exchange membrane; and an anode-side fluid discharge path for discharging anode-side fluid from the anode chamber; wherein the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is greater than the effective flow path cross-sectional area CS of the cathode-side fluid supply path; the effective flow path cross-sectional area AD of the anode-side fluid discharge path is greater than the effective flow path cross-sectional area AS of the anode-side fluid supply path; and the effective flow path cross-sectional area CD is 1.1 to 3.0 times the effective flow path cross-sectional area CS (CD = 1.1 to 3.0 CS). The effective flow path profile area AD is 1.1 to 3.0 times the effective flow path profile area AS (AD = 1.1 to 3.0 AS).

2. The electrolytic cell as described in claim 1, wherein, The effective flow path profile area CD is 1.5 to 2.5 times the effective flow path profile area CS (CD = 1.5 to 2.5CS); the effective flow path profile area AD is 1.5 to 2.5 times the effective flow path profile area AS (AD = 1.5 to 2.5AS).

3. The electrolytic cell as described in claim 1 or 2, wherein, The cathode frame is provided with at least one upper flow path extending from an upper opening at the upper end of the inner surface, and at least one lower flow path extending from a lower opening at the lower end of the inner surface; the anode frame is provided with at least one upper flow path extending from an upper opening at the upper end of the inner surface, and at least one lower flow path extending from a lower opening at the lower end of the inner surface; the cathode plate extends continuously from above the upper opening of the cathode frame to below the lower opening of the cathode frame; at least one upper through opening matching the upper opening of the cathode frame is formed at the upper end of the cathode plate, and at least one lower through opening matching the lower opening of the cathode frame is formed at the lower end of the cathode plate; the anode plate extends continuously from above the upper opening of the anode frame to below the lower opening of the anode frame; At least one upper through-opening matching the upper opening of the anode frame is formed at the upper end of the anode plate, and at least one lower through-opening matching the lower opening of the anode frame is formed at the lower end of the anode plate; the upper through-opening of the cathode plate and the upper flow path of the cathode frame constitute one of the cathode-side fluid discharge path and the cathode-side fluid supply path, and the lower through-opening of the cathode plate and the lower flow path of the cathode frame constitute the other of the cathode-side fluid discharge path and the cathode-side fluid supply path; the upper through-opening of the anode plate and the upper flow path of the anode frame constitute one of the anode-side fluid discharge path and the anode-side fluid supply path, and the lower through-opening of the anode plate and the lower flow path of the anode frame constitute the other of the anode-side fluid discharge path and the anode-side fluid supply path.

4. The electrolytic cell as described in claim 3, wherein, The cathode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings spaced apart along the width direction from the upper end of the inner surface, and a plurality of lower flow paths extending from a plurality of lower openings spaced apart along the width direction from the lower end of the inner surface; the anode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings spaced apart along the width direction from the upper end of the inner surface, and a plurality of lower flow paths extending from a plurality of lower openings spaced apart along the width direction from the lower end of the inner surface; at the upper end of the cathode plate, a plurality of upper through openings are formed that match each of the plurality of upper openings of the cathode frame, and at the lower end of the cathode plate, a plurality of lower through openings are formed that match each of the plurality of lower openings of the cathode frame; At the upper end of the anode plate, a plurality of upper through openings are formed, each matching one of the plurality of upper openings of the anode frame; at the lower end of the anode plate, a plurality of lower through openings are formed, each matching one of the plurality of lower openings of the anode frame. The number of upper through openings of the cathode plate and upper flow paths of the cathode frame constituting the cathode-side fluid discharge path, or the number of lower through openings of the cathode plate and lower flow paths of the cathode frame, is greater than the number of lower through openings of the cathode plate and lower flow paths of the cathode frame constituting the cathode-side fluid supply path, or the number of upper through openings of the cathode plate and upper flow paths of the cathode frame. The number of the upper through opening of the anode plate and the upper flow path of the anode frame constituting the anode-side fluid discharge path, or the number of the lower through opening of the anode plate and the lower flow path of the anode frame, is greater than the number of the lower through opening of the anode plate and the lower flow path of the anode frame constituting the anode-side fluid supply path, or the number of the upper through opening of the anode plate and the upper flow path of the anode frame.

5. The electrolytic cell as described in claim 4, wherein, The upper and lower openings of the cathode frame, as well as the upper and lower through openings of the cathode plate, have a circular cross-sectional shape; the upper and lower openings of the anode frame, as well as the upper and lower through openings of the anode plate, have a circular cross-sectional shape.

6. The electrolytic cell as described in claim 3, wherein, The cathode plate and the anode plate are both made of rectangular plates.

7. A method for producing an aqueous solution of quaternary ammonium hydroxide, comprising using an electrolytic cell as described in claim 1 or 2, and using an aqueous solution of quaternary ammonium salt as a raw material to produce the aqueous solution of quaternary ammonium hydroxide, wherein, The electrolytic cell has at least one cation exchange membrane disposed between the cathode plate and the anode plate.

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