JP4599487B2 - Water-cooled vertical electrolytic cell - Google Patents

Description

The present invention relates to an electrolytic cell for electrolytically oxidizing a chlorine ion solution to produce water for sterilization. More specifically, it has a structure that regulates the flow of liquid inside, minimizes the mixing of reaction products and raw materials, removes generated heat quickly by water cooling, efficiently continues the electrolytic oxidation reaction, and reduces the influence on the electrode. It relates to an electrolytic cell.

Many techniques are known for electrolytically oxidizing a chloride ion solution to produce water for sterilization. A system that electrolyzes salt solution in a diaphragm-type electrolytic cell and extracts hydrochloric acid acidic sterilizing water from the anode chamber (Patent Document 1), or an apparatus that electrolyzes salt in a non-diaphragm electrolytic cell to produce a sodium hypochlorite solution (patent) Document 2), an apparatus for producing slightly acidic electrolyzed water by electrolyzing dilute hydrochloric acid in a non-diaphragm electrolytic cell (Patent Document 3), etc. are representative. In these techniques, the electrolytic cell, which is an essential element, basically has the following problems. When manufacturing a large-scale device to cope with a large amount of use of sterilizing water, the internal temperature rises due to the large size of the electrolyzer, and (1) the efficiency of heat generated inside the electrolyzer deteriorates. However, there are problems that the electrode life is shortened and the electrolytic efficiency is lowered, and (2) the pressure resistance performance is reduced due to the enlargement of the electrolytic cell. When an electrolytic cell having a large capacity is manufactured, the electrolytic current naturally increases and the volume also increases. In other words, the amount of heat generation increases and the heat dissipation effect also deteriorates, so that the internal temperature rise is overlapped. In order to cope with this, the present inventors previously invented an electrolytic cell provided with a cooling jacket around the electrolytic cell (Patent Document 4). However, since this method only cools the outer peripheral surface of the electrolytic cell, there is a drawback that the cooling effect decreases as the volume of the electrolytic cell increases. There was no measure for pressure resistance. On the other hand, the casing of the electrolytic cell needs to be an insulator in order to avoid leakage current, and a single material such as glass, ceramic, plastic, or a composite material with metal is used. However, plastic is often used because of its ease of manufacture and low price. However, the physical strength of plastics decreases as the electrolytic cell size increases, and the restrictions on the use conditions increase and become a problem. In order to deal with the problem, it was necessary to add reinforcement parts for the electrolytic cell itself, use a valve to lower the water pressure, and take measures to avoid water hammer. Furthermore, since no pressure is applied to the outlet side of the electrolytic cell, there are various restrictions on the piping structure.
Patent 2896122 JP 4-028438 JP-A-10-128336 Japanese Patent Application No. 2004-39011

The problem to be solved by the present invention is that an electrolytic cell used in a method for producing a sterilizing water by electrolytically oxidizing a chlorine ion solution in an electrolytic cell and diluting an electrode oxidizing solution with water has a small temperature rise even at a large capacity. It is to provide an electrolytic cell with high pressure resistance.

In order to solve the problems, the present inventor has (1) the electrolytic cell has a double casing structure, (2) the outer casing is cylindrical to provide pressure resistance, and (3) the inner casing is electrolyzed. Considering performance and heat transfer performance, a rectangular parallelepiped structure was adopted. The outer casing can be formed as a structure necessary for pressure resistance if the diameter of the cylinder is 180 mm, but is 150 mm or less . The dilution water is allowed to flow down into the space between the external enclosure and the internal enclosure, and the electrolytic oxidation solution generated in the internal enclosure is discharged into the dilution water in the external enclosure, and dilution mixing is performed in the external enclosure. The structure was completed. Furthermore, in order to adjust the flow of liquids during electrolysis, the electrode plate has a vertically long shape, and the ratio of long / short is possible to be 2 or more, but 4 or more , and the internal housing and the external housing are combined into a vertically long shape. .

By adopting such a structure, the following advantages were obtained. (1) First, by making the electrolytic cell into a double structure, diluted water was allowed to flow through the gap to obtain a cooling effect, and the high-concentration electrolytic oxidation solution generated in the internal housing was the electrode terminal. There is no longer any risk of leaking directly from the seal part of the rod. This simplifies the terminal rod sealing structure and eliminates the need for expensive sealing materials. Furthermore, since the pressure resistance performance and the electrolysis performance can be carried on separate housings, it becomes possible to select a shape convenient for each function.

(2) Along with this, it was possible to select a cylindrical shape advantageous in terms of pressure resistance structure as the shape of the external casing. The pressure resistance of ready-made vinyl chloride pipes according to JIS is 25.5 kg / cm ² (VP), 20.4 kg / cm ² (VM), and 15.3 kg / cm ² (VU), depending on the type. Is decided. Therefore, it is not the cylindrical part but the end face that has a problem with pressure resistance. Therefore, the upper limit of the diameter of the cylinder for which the end face treatment can obtain a practical strength was calculated. The tensile strength (σ) of the welded portion of general industrial hard vinyl chloride is expressed by Equation 1.
σ = σ _t × C × M × S = 95 (kg / cm ² ) (Formula 1)
“However, σ _t is 570 kg / cm ² (20 ° C.) as the tensile strength of hard vinyl chloride for general industrial use, C is 1/2 for creep, M is 1/3 for welding efficiency, and S is 1 for safety factor. "
Next, the pressure resistance when a disk is bonded to the end face by circumferential welding is calculated by Equation 2.
P = σ × t ² / (α × D ² ) = 507 t ² / D ² (kg / cm ² )
“However, t is the plate thickness (cm), α is the tensile strength coefficient (3/16) at the time of constant weight distribution, D is the inner diameter of the tube (cm)”
The thickness and 2 cm, since the pressure of the water or industrial water, which is normally utilized is 2-3 kg / cm ^2, a safety factor taking into account the instantaneous pressure variations ² (6kg / cm 2) or 3 (9 kg / Cm ² ), the upper limit of the tube diameter is calculated to be 18 cm and 15 cm, respectively. This is the upper limit of the tube diameter for practical pressure resistance. Further, by using a cylinder for the outer casing, there is an advantage that an inexpensive ready-made member can be used.

(3) The shape of the inner casing is a rectangular parallelepiped that is optimal for storing rectangular electrode plates arranged at equal intervals without creating a useless space. Since the internal casing does not need to withstand pressure, it can be determined considering only the efficiency of electrolysis. A rectangular parallelepiped with a large specific surface area is advantageous because the entire inner surface of the inner casing comes into contact with the diluted water and becomes a heat transfer surface. Moreover, in order to promote the natural flow of the electrolyte, a vertically long structure was adopted. This facilitates the upward flow of the gas generated by electrolysis and the electrolyte heated by electrolysis, preventing mixing of newly supplied hydrochloric acid and the electrolyzed liquid, and switching is performed smoothly. It is. Thereby, the efficiency of electrolysis is kept high.

As the chloride ion solution used in this electrolytic cell, hydrochloric acid, sodium chloride, potassium chloride, calcium chloride, ammonium chloride can be used according to the purpose.

The effect of the present invention is that the electrolytic cell used in the method of electrolytically oxidizing a chlorine ion solution in an electrolytic cell and diluting the electrode oxidizing solution with water to generate sterilizing water has a small temperature rise even with a large capacity, and has a pressure resistance performance. It is that a high electrolytic cell was provided. The pressure resistance of the electrolytic cell according to the present invention is 6 kg / cm ² or more when designed with a safety factor of 2 and 9 kg / cm ^{2 when} designed with a safety factor of 3, and has sufficient pressure strength for practical use. Therefore, there are almost no restrictions on the specifications of the process before and after the electrolytic cell, and the number of parts for pressure adjustment is reduced and the degree of freedom of equipment is increased.
On the other hand, in the structure of the present invention, it is extremely easy to design the difference between the temperature inside the electrolytic cell and the dilution water to be 10 ° C. or less, and consumption of electrodes and plastic members due to unnecessary temperature rise in the electrolytic cell is reduced. It is possible to suppress the running cost by extending the life of the electrolytic cell.
Furthermore, the electrolytic cell has a vertically long shape, the raw material solution supply port is on the bottom, and the electrolyte discharge port is on the top surface, making it easy to move the material in the vertical direction and smoothly removing the gas generated by the electrolysis. The effect is that the electrolytic solution whose temperature has risen can be easily moved to the upper part, unnecessary mixing of the newly supplied raw material solution and the electrolysis result substance can be avoided, and the electrolytic efficiency can be maintained high.

In the best mode of the present invention, an electrode group configured by arranging plate electrodes having a vertical / horizontal ratio of 4 or more in parallel is housed in a rectangular parallelepiped housing, and the longitudinal direction of the housing is disposed vertically. The structure is such that a chlorine ion solution is supplied from the lower surface of the housing and the electrolytic product is discharged from the upper surface of the housing. The rectangular parallelepiped housing thus configured is further accommodated in a cylindrical housing. The inner diameter of the cylindrical casing is 150 mm or less in order to maintain a practical pressure resistance. A structure in which dilution water is passed through the gap between the cylindrical casing and the rectangular parallelepiped casing, and the electrolytic product discharged from the upper surface of the rectangular casing is mixed and diluted in the diluted water in the cylindrical casing. To do. The external cylindrical housing is provided with a dilution water supply pipe and a discharge pipe for diluting water mixed with electrolytic products. A power cord for supplying a current to the electrode housed in the internal rectangular parallelepiped housing passes through the external cylindrical housing, penetrates the rectangular parallelepiped housing, and is joined to the electrode. Similarly, the pipe for supplying the chlorine ion solution also passes through the external cylindrical casing and is joined so that the liquid can be supplied into the rectangular parallelepiped casing. The discharge port for the electrolyte is a fine hole directly drilled in the upper surface of the internal rectangular parallelepiped housing.
The optimum chloride ion solution to be electrolyzed in this electrolytic cell is a hydrochloric acid solution, a sodium chloride solution or a mixture thereof. The actual dimensions of the electrodes are appropriately determined in consideration of durability based on the current value determined by the electrolytic capacity.

Next, examples will be shown to explain the present invention in more detail, but the purpose is not to limit the scope of the present invention to this example, but to deepen the understanding of the present invention.

FIG. 1 shows a drawing of the embodiment. The electrode was formed by coating a titanium base plate with platinum (manufactured by Tanaka Kikinzoku Co., Ltd.), and the electrode group 10 was constructed by arranging 13 sheets with a thickness of 1 mm, a width of 70 mm, and a length of 600 mm at intervals of 3 mm. Each of the outer sides used a welded terminal bar 5 for power feeding. The electrode group was housed in the inner rectangular parallelepiped housing 2. The rectangular parallelepiped housing is provided with a hydrochloric acid supply opening 7, a hydrochloric acid dilution water supply opening 6, and an electrolyte discharge opening 8. The rectangular parallelepiped housing was composed of a hard vinyl chloride plate having a thickness of 10 mm. The rectangular parallelepiped housing was further stored in the cylindrical housing 1. The cylindrical housing was made of a rigid vinyl chloride tube with a diameter of 125 mm. The cylindrical housing is provided with a diluting water inflow opening 3 and an electrolyte mixed diluting liquid discharge opening 4, and further provided with a mechanism 11 for joining the front and rear piping members at both ends. The raw hydrochloric acid is supplied into the rectangular parallelepiped housing through the hydrochloric acid supply opening 7, and is diluted with water supplied from the hydrochloric acid dilution water supply opening and supplied into the electrode group. Therefore, the electrolytically oxidized electrolyte is discharged from an electrolyte discharge opening provided on the upper surface. On the other hand, the diluted water is supplied from the lower opening 3, passes through the gap 9 between the rectangular parallelepiped casing and the cylindrical casing, reaches the discharge port 4, where it is mixed with the electrolyte discharged from the rectangular parallelepiped casing and discharged.
An electrolyzer using this electrolyzer was created and the performance was confirmed. FIG. 2 shows the flowchart. From the raw water intake port 16, 5000 L of raw water per hour was taken and allowed to flow down into the gap between the inner rectangular parallelepiped casing and the outer cylindrical casing of the electrolytic cell. A portion of the raw water was extracted from the middle of the raw water supply pipe with a metering pump 15 (EH-E35FC, manufactured by Iwaki Co., Ltd.), and supplied to the cuboid enclosure. From the hydrochloric acid tank 13, 21% hydrochloric acid was supplied to a 500 ml cuboid body per hour with a metering pump 14 (EH-B15VC manufactured by Iwaki Co., Ltd.), mixed with the raw water supplied with the metering pump 15, and supplied to the electrode group. 12V, 12A power is supplied to the electrode group from a DC power supply (RAW12 not shown by TDK), the supplied hydrochloric acid solution is continuously electrolyzed, the electrolyte is discharged from the top surface of the rectangular parallelepiped, and flows down there. The diluted water was mixed and diluted, and the sterilizing water was discharged from the discharge unit 17. With this apparatus, 5000 L of sterilizing water per hour was continuously obtained.

Electrolytic cell drawing, I is a longitudinal section parallel to the electrode, II is a longitudinal section perpendicular to the electrode, III is a bottom view Flow diagram of an electrolyzer incorporating an electrolytic cell

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 External cylindrical housing 2 Internal rectangular housing 3 Dilution water inflow opening 4 Mixed dilution liquid discharge opening 5 Terminal bar 6 Hydrochloric acid dilution water supply opening 7 Hydrochloric acid supply opening 8 Electrolyte discharge opening 9 Rectangular body housing and cylindrical housing 10 Electrode group 11 Structure joined to piping members before and after 12 Electrolyzer 13 Hydrochloric acid tank 14 Hydrochloric acid metering pump 15 Hydrochloric acid diluted water metering pump 16 Raw water intake 17 Disinfecting water outlet 18 Opening / closing valve (HG-A manufactured by Hokuetsu) -WF50-100V)

Claims (3)

The electrolytic cell used for the method of electrolytically oxidizing the chloride ion solution in the electrolytic bath and diluting the electrode oxidizing solution with water to generate sterilized water has the following items,
(1) The electrode is a rectangular flat plate having a uniform thickness, the longitudinal direction is arranged in the vertical direction, and
(2) The flat plate is included in a rectangular parallelepiped box, and
(3) The flow of liquid in the rectangular parallelepiped enclosure is from the bottom to the top, and
(4) The rectangular parallelepiped casing is further included in a cylindrical outer casing, and
(5) A structure in which dilution water flows through a gap between a rectangular parallelepiped casing and a cylindrical outer casing, and
(6) The chlorine ion solution supplied into the rectangular parallelepiped enclosure is subjected to electrolytic oxidation, and the electrolytic oxidation solution is discharged from the upper surface of the rectangular parallelepiped into the cylindrical outer casing, and mixed and diluted with dilution water flowing therethrough. Electrolyzer characterized by having a structure 2. The electrolytic cell according to claim 1, wherein an inner diameter of the cylindrical outer casing according to claim 1 is 150 mm or less. 3. The electrolytic cell according to claim 1 or 2, wherein the flat electrode plate according to claim 1 has a longitudinal / shorter ratio of 4 or more.