JP2022072743A - Aqueous solution production device, electrolytic tank unit and production method - Google Patents

Abstract

To provide a production device capable of attaining the optimization of the service life of electrodes and an electrolytic tank by effectively cooling the electrolytic tank, and stably producing an aqueous solution within the range of target properties in a normal electrolytic operation.SOLUTION: A production device of an aqueous solution comprises: an electrolytic tank; plural electrodes provided at the inside of the electrolytic tank; one or more unit cells respectively formed between the electrodes in the electrolytic tank; and a solution feed passage for feeding a raw material solution into the electrolytic tank. The production device further comprises: a water feed passage for feeding cooling water into each of the one or more unit cells, independently of the raw material solution; an exhaust port for exhausting an electrolytic solution produced by the electrolysis of the raw material solution from the one or more unit cells; and a power supply device for flowing an electric current to a space between the plural electrodes.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to an aqueous solution manufacturing apparatus, an electrolytic cell unit, and a manufacturing method. More specifically, the present disclosure relates to a manufacturing apparatus for producing an aqueous solution by electrolyzing a solution containing chloride ions, an electrolytic cell unit used for producing the aqueous solution, and the present invention for producing the aqueous solution. Regarding the manufacturing method of.

A technique for producing an aqueous solution containing free hypochlorous acid by electrolyzing and diluting a solution containing chloride ions, for example, hydrochloric acid alone or a mixed solution of hydrochloric acid and sodium chloride or potassium chloride under predetermined conditions. Are known. This generated aqueous solution is used in a wide range of fields because free hypochlorous acid acts as a bactericidal component and exhibits a bactericidal effect against a wide range of microorganisms. Among the above-mentioned aqueous solutions containing free hypochlorous acid, the slightly acidic hypochlorous acid water produced from hydrochloric acid or an aqueous solution prepared by adding an aqueous solution of sodium chloride to hydrochloric acid is also designated for sterilization of food additives. It is known to have many excellent features.

Due to its many excellent characteristics, the field of use of slightly acidic hypochlorous acid water is extremely wide-ranging, and the food processing field (milk / dairy products, beverages, alcoholic beverages, confectionery, prepared foods, fishery processing, agricultural and livestock processing, etc.) ), Medical care field, sports and leisure play facilities, agriculture and fisheries field (paddy rice cultivation, fruit tree gardening, vegetable cultivation factory, livestock poultry farming, aquaculture, etc.), and also in general household hygiene management, etc. It is used as a bactericidal agent.

Slightly acidic hypochlorous acid water is produced by electrolyzing a chloride ion-containing solution such as hydrochloric acid in a non-diabolic electrolytic cell and diluting the obtained electrolytic solution with water. In this technique for producing slightly acidic hypochlorous acid water, the required points are stable electrolysis operation of the manufacturing equipment, stable generation of slightly acidic hypochlorous acid water having an effective chlorine concentration and pH within a predetermined range, and an electrode. And the life of the electrolytic cell can be mentioned.

However, there are cases where a high concentration of effective chlorine is required at the site of use in a specific field, and there are many cases where the user puts a load on the device and continuously stresses it. Therefore, there are some situations where the conventional electrolytic design cannot sufficiently cope.

For example, under certain conditions that depend on the quality and usage of raw water, for example, operational anxiety due to abnormal electrolysis, deviation from the target range of effective chlorine concentration and pH, shortening of the life of electrodes and electrolytic cells. In some cases, such a problem occurred.

One of the physical conditions that affect the life of the electrodes and the electrolytic cell described above is the heat generated by electrolysis. It is suitable for the life of the electrode to suppress the temperature rise around the electrode as much as possible.

Japanese Patent Application Laid-Open No. 2019-198820 (Patent Document 1) is known in relation to an electrode due to heat generation. Patent Document 1 discloses a technique for providing a method for producing an aqueous solution capable of preventing deterioration of an electrode due to electrolytically generated hydrogen and generated heat and safely discharging hydrogen. do. The prior art of Patent Document 1 discloses a method for producing an aqueous solution containing at least free hypochlorous acid, which comprises a step of mixing a gas with a chlorine ion-containing solution in a mixing chamber. The mixed gas has the effect of stirring the solution in the electrolytic cell, and the heat of vaporization of some liquid vaporizing into the bubbles has the effect of cooling the inside of the electrolytic cell. , The heat generated by the electrode is absorbed and the temperature rise of the electrode is suppressed. Further, in the prior art including the above-mentioned Patent Document 1, a double-shell structure electrolytic cell composed of an inner tank and an outer tank is used to cool the inner tank in which electrolysis is performed by the raw water stored in the outer tank. Is being done.

Even in the above-mentioned conventional technique, the inside of the electrolytic cell can be cooled to a certain extent by the raw water flowing through the outer tank in the double-shell structure electrolytic cell. As a result of diligent studies by the inventors regarding the above-mentioned problems, the cooling of the outer tank with raw water in the double-shell structure electrolytic cell may not be sufficient to cool the central part of the electrolytic cell under specific conditions. It was found that the rise in temperature could cause problems such as operational anxiety due to abnormal electrolysis and shortening of the life of the electrode or electrolytic cell. In addition, it was designed to lower the internal temperature and alleviate the high temperature state by partially backflowing the raw water into each unit cell from the discharge port communicating with the outer tank. However, there are still issues to be improved regarding the continuation and stabilization of the specified properties under specific conditions. The inventors have identified this problem and elucidated a method for stabilizing it.

The present disclosure has been made in view of the above points, effectively cooling the electrolytic cell, optimizing the life of the electrode and the electrolytic cell, and performing normal electrolysis operation of the aqueous solution within the target property range. It is an object of the present invention to provide a manufacturing apparatus, an electrolytic cell unit and a manufacturing method capable of stably producing in the above.

As a result of diligent studies, the present inventors have efficiently cooled the inside of the electrolytic cell including the central portion by providing a path for supplying cooling water into each unit cell of the electrolytic cell independently of the raw material solution. It has been found that it is possible to stably generate an aqueous solution within the target property range by normal electrolysis operation, and it is possible to prevent the life of the electrode and the electrolytic cell from being shortened. This is what led to the present invention.

That is, in order to solve the above problems, the present invention provides an aqueous solution producing apparatus having the following characteristics. The manufacturing apparatus includes an electrolytic cell, a plurality of electrodes provided in the electrolytic cell, and one or more unit cells formed between the electrodes in the electrolytic cell. The manufacturing apparatus also applies a current between a solution supply path for supplying the raw material solution to the electrolytic cell, a discharge port for discharging the electrolytic solution generated by electrolysis of the raw material solution from one or more unit cells, and a plurality of electrodes. It is equipped with a power supply device to flow. The manufacturing apparatus further includes a water supply channel for supplying cooling water to each of one or more unit cells independently of the raw material solution.

In a preferred embodiment, the manufacturing apparatus further comprises a solution supply pump connected to the solution supply channel and a water supply pump connected to the water supply channel and operating asynchronously with the solution supply pump. In a more preferred embodiment, the water supply pump is characterized by supplying cooling water intermittently or continuously / quantitatively, and the manufacturing apparatus controls the operation of the solution supply pump based on the measured value of the current by the power supply device. Further equipped with a control device. Further, the control device supplies cooling water to the water supply pump during the electrolysis period except for the step of boosting the voltage of the power supply device based on the measured value of the current by the power supply device starting from the start of electrolysis. Can be done. The water supply pump can preferably supply the cooling water through the solution supply path at a flow rate having an average residence time of 750 seconds or less per unit cell.

In certain embodiments, one outlet may be provided for each unit cell. In another specific embodiment, a plurality of discharge ports are provided for each unit cell, and the manufacturing apparatus has a common discharge flow path for collecting electrolytic solutions from the discharge ports of one or more unit cells. The electrolytic cell may be further provided with a common discharge port for discharging the collected electrolytic solution. Further, in a specific embodiment, the water supply channel may supply cooling water to the inlet of each of one or more unit cells independently of the solution supply path, or to the front stage of the inlet of each of one or more unit cells. It may be independent of the solution supply path and may share a part of the flow path with the solution supply path in the previous stage.

In a preferred embodiment, the manufacturing apparatus is provided on the outside of the electrolytic cell so as to surround the electrolytic cell, communicates with the electrolytic cell, dilutes the electrolytic solution discharged from the electrolytic cell with raw water, and cools the electrolytic cell with the raw water. It may be further provided with a diluting tank to be used and an outlet for taking out the diluting aqueous solution from the diluting tank.

Further, in a specific embodiment, the plurality of electrodes are each in the shape of a plate, and in the electrolytic cell, the plurality of electrodes are arranged in parallel, the two outermost electrodes are fed and connected, and both outermost electrodes are connected. At least one non-feeding connection electrode is a multipolar electrolytic cell arranged in parallel between two power supply-connected electrodes, and a raw material solution is supplied to each unit cell, and each unit cell is provided with a raw material solution. Therefore, the electrolytic solution may be discharged.

In certain embodiments, the plurality of electrodes comprises a substrate containing titanium, or an alloy containing titanium, and the raw material solution comprises one or more substances selected from the group consisting of hydrogen chloride, sodium chloride and potassium chloride. It is characterized by being a dissolved chloride ion-containing solution.

Further, according to the embodiment of the present invention, it is possible to provide an electrolytic cell unit having the following characteristics. The electrolytic tank unit supplies a raw material solution to each of an electrolytic tank, a plurality of electrodes provided in the electrolytic tank, one or more unit cells formed between the electrodes in the electrolytic tank, and one or more unit cells. A solution supply channel for supplying cooling water to each of one or more unit cells independently of the raw material solution, and a raw material solution provided and supplied to each of one or more unit cells. It is provided with a discharge port for discharging the electrolytic solution generated by electrolysis. In a preferred embodiment, the water supply channel and the solution supply channel may be connected to a water supply pump and a solution supply pump that operate asynchronously with each other, respectively.

Further, according to the embodiment of the present invention, it is possible to further provide a method for producing an aqueous solution having the following characteristics. The manufacturing method includes a step of supplying a raw material solution to each of one or more unit cells provided in an electrolytic cell via a solution supply path. The manufacturing method further includes a step of passing an electric current between a plurality of electrodes provided in the electrolytic cell and electrolyzing the raw material solution supplied to each unit cell to generate an electrolytic solution. The production method also comprises the step of supplying cooling water to each of one or more unit cells via a water supply channel independently of the raw material solution. The manufacturing method includes a step of discharging the electrolytic solution from each unit cell and a step of diluting the discharged electrolytic solution with raw water.

In a preferred embodiment, the step of supplying the cooling water is performed by a water supply pump controlled asynchronously with the raw material pump that supplies the raw material solution through the solution supply path.

With the above configuration, it is possible to effectively cool the electrolytic cell, optimize the life of the electrode and the electrolytic cell, and stably generate an aqueous solution within the target property range by normal electrolysis operation. ..

The whole block diagram of the slightly acidic hypochlorous acid water production apparatus by this embodiment. It is sectional drawing which shows the detailed structure of the double-shell structure electrolytic cell by this embodiment. Top view of the double shell structure electrolytic cell according to this embodiment. The figure explaining how to attach the electrolytic cell unit to the outer tank by this embodiment. The perspective view of the electrolytic cell unit by this embodiment. The flowchart which shows the embodiment of the manufacturing method of slightly acidic hypochlorous acid water. The flowchart which shows the acclimatization process at the start of electrolysis performed in a specific embodiment. The chart which shows the pump operation by a preferable embodiment. A graph showing the temperature change measured at the electrolyte and gas outlets of a rectangular electrolytic cell. The graph which shows the time change of the current value at the time of restart after stopping electrolysis during stable operation. The graph which shows the time change of the effective chlorine concentration and pH at the time of restart after stopping electrolysis during continuous operation.

Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited to the specific embodiments shown in these drawings.

FIG. 1 is an overall configuration diagram of a manufacturing apparatus (hereinafter, simply referred to as a manufacturing apparatus) 50 for producing slightly acidic hypochlorous acid water according to the present embodiment.

The manufacturing apparatus 50 shown in FIG. 1 includes a double-shell structure electrolytic cell 40, and the double-shell structure electrolytic cell 40 is provided in the inner tank 20 and outside the inner tank 20, and the inner tank 20 is provided. It is configured to include an outer tank 32 configured to surround the outer tank 32.

The inner tank 20 functions as an electrolytic cell for producing an electrolytic solution containing hypochlorous acid by electrolysis of the raw material solution. The electrolytic solution containing a relatively high concentration of hypochlorous acid generated in the inner tank 20 is a space in the outer tank 32 outside the inner tank 20 from the opening 28 provided in the ceiling of the inner tank 20. Is discharged to.

The outer tank 32 communicates with the inner tank 20 through the opening 28, and serves as a diluting tank for diluting the generated electrolytic solution. The outer tank 32 is filled with water (hereinafter referred to as raw water) for diluting the generated electrolytic solution and cooling the inner tank 20. The outer tank 32 is provided with a raw water supply port 33, and the raw water 34 supplied from the raw water supply port 33 dilutes the electrolytic solution while cooling the inner tank 20 immersed in the outer tank 32. Further, the upper portion of the outer tank 32 is sealed by the outer tank lid portion 39, and the outer tank lid portion 39 is provided with an outlet 35 for taking out the diluted aqueous solution from the outer tank 32. Then, the diluted electrolytic solution has an effective chlorine concentration in a predetermined range and a pH in a predetermined range, and is discharged from the outlet 35 as a slightly acidic hypochlorous acid water 36 to the outside of the double-shell structure electrolytic cell 40. Will be done.

Here, the slightly acidic hypochlorous acid water is a kind of hypochlorite water (an aqueous solution containing hypochloric acid as a main component obtained by electrolyzing hydrochloric acid or an aqueous solution of sodium chloride), and is composed of hydrochloric acid and sodium chloride. An aqueous solution obtained by electrolyzing a raw material solution adjusted to an appropriate concentration by adding an aqueous solution of sodium chloride as needed in a diaphragmless electrolysis tank. The effective chlorine concentration of the slightly acidic hypochlorous acid water is 10 to 80 mg / L, and the pH range is 5.0 to 6.5.

The raw material solution is stored in the raw material tank 1, and the raw material supply port 30 is provided in the outer tank lid 39 that seals the outer tank 32. The raw material solution is supplied from the raw material supply port 30 to the inner tank 20 inside the raw material supply port 30 via the raw material supply pipe 2 using the raw material solution supply pump 3. In the present embodiment, the main component of the raw material solution is a hydrogen chloride solution. In a specific embodiment, the raw material solution can be stored in the raw material tank 1 at a desired hydrochloric acid concentration and directly supplied to the double-shell structure electrolytic cell 40. In another specific embodiment, the raw material solution may be stored in the raw material tank 1 at a predetermined concentration, diluted with raw water to a desired hydrochloric acid concentration, and then supplied to the double-shell structure electrolytic cell 40. Hereinafter, the entire route for supplying the raw material solution from the raw material tank 1 to the inside of the inner tank 20 (more specifically, a unit cell in the inner tank 20, the details of which will be described later) via the raw material supply pipe 2 and one thereof. Refer to the section and refer to the solution supply path.

In the manufacturing apparatus 50 according to the present embodiment, the water source is further cooled from the water source to the inside of the inner tank 20 (more specifically, it is a unit cell in the inner tank 20 and details will be described later). A route for supplying water 4 is provided. The outer tank lid 39 is provided with a cooling water supply port 37. The cooling water 4 is supplied to the inner tank 20 inside the cooling water supply port 37 via the water supply pipe 5 by using the water supply pump 6 with a water tap, a water storage tank, or the like as a water source. Hereinafter, the entire path for supplying cooling water from the water source to the inside of the inner tank 20 via the water supply pipe 5 (more specifically, it is a unit cell in the inner tank 20 and details will be described later) and a part thereof will be referred to. Then, it is called a water supply channel.

The manufacturing device 50 shown in FIG. 1 further includes a power supply device 41, a current measuring unit 42, and a control device 43. The outer tank lid 39 is provided with two power feeding terminals 29. The power supply device 41 is electrically connected to two power supply terminals 29 provided on the outer tank lid 39, and a direct current is passed between a plurality of electrodes of the inner tank 20 inside the double-shell structure electrolytic cell 40. .. The value of the current flowing between the two feeding terminals 29 is measured by the current measuring unit 42. The current value measured by the current measuring unit 42 is given to the control device 43.

The control device 43 controls the operation of the raw material solution supply pump 3 based on the measured value of the current, and manages the supply of the raw material solution to the inner tank 20. For example, the range of the measured value of the current is set in advance in the control device 43, and when the measured value of the current is lower than the lower limit of the range, the raw material solution supply pump 3 is operated to start the supply of the raw material. When the measured value of the current exceeds the upper limit of the range, the raw material solution supply pump 3 is stopped and the supply of the raw material is stopped.

Further, the control device 43 also controls the voltage applied between the two feeding terminals 29, and in a specific embodiment, a mode in which the voltage is adjusted based on the measured value of the current at the start of electrolysis (hereinafter referred to as a habituation mode). The process / process performed in the acclimatization mode may be referred to as acclimatization or acclimatization process). In the acclimatization mode, the control device 43 attempts to increase the voltage from the initial voltage until the measured value of the current reaches the target value. When the measured value of the current reaches the target value, the control device 43 repeatedly operates and stops the raw material solution supply pump 3 based on the upper limit value and the lower limit value of the current in the same manner as the above-mentioned normal operation. The voltage is lowered to the normal set voltage (voltage suitable for chlorine generation) at a predetermined rate. If the measured value of the current cannot reach the target value even when the set maximum voltage is reached, the operation of the raw material solution supply pump 3 is started as it is. With this acclimation mode, it is possible to easily secure a normal current at the start of electrolysis even in a state where deterioration of the electrodes and the inner tank 20 begins to be observed.

In the embodiment in which the raw material solution is diluted with raw water before being supplied to the double-shell structure electrolytic cell 40, the control device 43 controls a dilution pump (not shown) in synchronization with the raw material solution supply pump 3, and raw water is added to the raw material solution. May be mixed to supply the diluted raw material solution from the raw material supply port 30.

The control device 43 according to the present embodiment further controls the water supply pump 6 asynchronously with the raw material solution supply pump 3 to supply the cooling water 4 to the inner tank 20. In a preferred embodiment, the water supply pump 6 is a unit cell inside the inner tank 20 (more specifically, a unit cell in the inner tank 20) with the cooling water 4 intermittently or continuously / quantitatively, and the details will be described later. ) Can be supplied. Further, it is preferable that the control device 43 controls the water supply pump 6 asynchronously with the pump supplied by the raw water 34, and supplies the cooling water 4 to the inner tank 20.

Although the internal structure of the inner tank 20 is omitted in FIG. 1, these will be described later with reference to FIGS. 2 to 5. The unit including the inner tank 20 shown in FIG. 1 is hereinafter referred to as an electrolytic cell unit 60 in the present embodiment.

Hereinafter, the electrolytic cell unit 60 (inner tank 20) in the manufacturing apparatus 50 according to the present embodiment will be described in more detail with reference to FIGS. 2 to 5.

2 (A) and 2 (B) are cross-sectional views showing a structure including the inside of the inner tank 20 of the double-shell structure electrolytic cell 40 according to the present embodiment. FIG. 3 is a top view of the double-shell structure electrolytic cell 40 according to the present embodiment. 2 (A) shows the arrow A seen from the arrow A shown in FIG. 3, and FIG. 2 (B) shows the arrow B seen from the arrow B shown in FIG. 2 (A) and 2 (B) show a cross-sectional view of the inner tank 20 with a cut surface perpendicular to the electrode surface of the electrode provided in the inner tank 20. Further, in FIG. 3, the outline of the rectangular inner tank 20 housed in the cylindrical outer tank 32 is shown by a broken line.

As shown in FIGS. 2A and 2B, a plurality of electrodes 24 are provided in parallel in the inner tank 20 which is an electrolytic cell with the surfaces facing each other. A power supply connection is made to the two outermost electrodes 24, an electrolytic current is supplied from the power supply device 41 shown in FIG. 1 via the power supply terminal 29, and a plurality of plate-shaped electrodes are provided in parallel. A multi-pole type non-septal electrolytic cell is formed.

At least one non-feeding connection electrode plate is arranged in parallel between the two power supply-connected electrodes on both outermost sides. By applying a direct current to both outermost plate-shaped electrodes in such a configuration, all of the intermediate plate-shaped electrodes not connected to the power supply among the plurality of plate-shaped electrodes 24 have an anode on one side and the opposite. The surface acts as a cathode, and a unit cell 31 is formed between them. In the embodiment described, the electrode 24 is a flat plate electrode, but the electrode 24 is parallel and is not limited to a flat plate as long as a uniform electric field can be formed, and is a parallel curved surface. It may be a shape that forms a.

The electrode 24 includes an electrode base material. Examples of the electrode base material include titanium or a material containing an alloy containing titanium. The anode surface of the electrode base material may be formed with iridium oxide, an oxide of ruthenium or osmium, a platinum film, or the like. Further, the electrode 24 may contain a trace amount of tantalum as a binder. The cathode surface of the electrode base material may be the electrode base material itself without treatment, or may have a coating of a substance containing a platinum group metal. However, from the viewpoint of reducing the manufacturing cost and the maintenance cost of the electrode and the inner tank 20, the coating of a substance containing a platinum group metal can be omitted.

The inner tank 20 is an insulating frame that surrounds the entire peripheral end surface of the electrode 24 in close contact with the electrode end surface together with the bottom portion 20b and the ceiling portion 20a in order to fix a plurality of electrodes 24 arranged at equal intervals in parallel. Form the structure. The inner tank 20 holds the side end of the electrode 24, and further isolates the electrolytic solution from the raw water. The inner tank 20 is not particularly limited, but is typically formed by using a resin such as vinyl chloride.

In the embodiment to be described, each rectangular parallelepiped space surrounded by a frame structure of two adjacent electrodes, a wall surface of the inner tank 20, a ceiling portion 20a and a bottom portion 20b is configured, and two electrodes adjacent to each other in the inner tank 20 are configured. Each unit cell 31 is formed between 24. FIG. 2 exemplifies an example in which three unit cells 31 are formed for four electrodes for convenience of explanation, but the number of electrodes and the number of unit cells associated therewith are not limited to 4 and 3. , Any number of electrodes (n) and corresponding number of cells (n-1) may be used. For example, in a specific mounting, 4 cells connected in series with 5 electrodes may be configured, and in another specific mounting, 10 cells, 9 cells, 12 cells, 11 cells, etc. may be arbitrarily configured according to the production capacity. can do.

The voltage applied per unit cell is preferably 0.5 V or more, 6.0 V or less, more preferably, from the viewpoint of increasing the chlorine generation efficiency and preventing quality deterioration due to the generation of by-products. It can be 1.5 V or more and 5.0 V or less. The current density is preferably 0.05 mA / mm ² or more, 1.2 mA / mm ² or less, from the viewpoint of preventing a decrease in the amount of electrolysis per unit area and an increase in the size of the device and suppressing wear of the electrodes. It can be more preferably 0.2 mA / mm ² or more and 1.00 mA / mm ² or less, and further preferably 0.7 mA / mm ² or more and 0.95 mA / mm ² or less. The electrode spacing can be preferably 0.5 mm or more and 10 mm or less, more preferably, from the viewpoint of facilitating the separation of bubbles generated during electrolysis and preventing deterioration of power efficiency. It is 1 mm or more and 8 mm or less.

The bottom 20b of the frame structure is provided with two connecting portions 30c and 37c for connecting pipes, respectively. The first connecting portion 30c is for connecting the pipe to the flow path inside the bottom portion 20b. One end of the electrolytic cell unit 60 (inner tank 20) is connected to the first connection portion 30c of the bottom portion 20b, and the other end is connected to the raw material supply port 30a provided in the outer tank lid portion 39 to supply the raw material solution. A first pipe 30b for supplying from the outside of the double-shell structure electrolytic cell 40 to the inside of the inner tank 20 is provided. The second connection portion 37c is also for connecting a pipe to the flow path inside the bottom portion 20b, and one end of the electrolytic cell unit 60 is connected to the second connection portion 37c of the bottom portion 20b and the other end. Is connected to the cooling water supply port 37a provided in the outer tank lid 39, and includes a second pipe 37b for supplying the cooling water from the outside of the double-shell structure electrolytic cell 40 to the inside of the inner tank 20. In order to improve safety, a check valve may be provided upstream of the connecting portions 30c and 37c (viewed from the normal flow) in a direction of blocking the liquid flow from the unit cell 31.

As an internal structure, the bottom portion 20b of the frame structure communicates with the first internal flow path 30d connected to the first connection portion 30c and the first internal flow path 30d, and in each rectangular parallelepiped space of the inner tank 20. , An individual raw material supply path 30e for individually supplying the raw material solution is provided. In the bottom portion 20b of the frame structure, as an internal structure, a second internal flow path 37d connected to the second connection portion 37c and a second internal flow path 37d are communicated with each other, and each rectangular parallelepiped space of the inner tank 20 is provided. In, an individual cooling water supply path 37e for individually supplying the cooling water is provided.

The first pipe 30b, the first connection portion 30c, the first internal flow path 30d, and the individual raw material supply path 30e for each unit cell provide a raw material solution to each of one or more unit cells 31 included in the electrolytic cell unit 60. It constitutes a solution supply path to be supplied. Similarly, the second pipe 37b, the second connection portion 37c, the second internal flow path 37d, and the individual cooling water supply passage 37e for each unit cell are independent of the raw material solution provided in the electrolytic cell unit 60. A water supply channel for supplying cooling water to each of the one or more unit cells 31 is configured.

In a preferred embodiment, the water supply channel for supplying the cooling water is the above-mentioned solution up to the inlet of each unit cell 31 (the opening on the unit cell 31 side of each individual cooling water supply channel 37e) as illustrated in FIG. It is preferable that it is provided independently of the supply channel. This is because the cooling water can be supplied into the unit cell completely independently of the raw material solution, which has a control advantage.

However, the present invention is not limited to this preferred embodiment, and the water supply channel for supplying the cooling water is independent of the solution supply path up to the front stage of the inlet of each unit cell 31, and is connected to the solution supply path in the front stage of the inlet. It does not prevent the adoption of a partially independent form in which some channels are common. For example, the second internal flow path 37d connected to the second connection portion 37c may communicate with the first internal flow path 30d connected to the first connection portion 30c, or may be an internal flow path. The individual flow paths 30e and 37e to the 30d and 37d and the unit cell 31 may be common. On the other hand, when the flow path is partially common, the raw material solution remaining in the common flow path is a unit together with the supply of cooling water even during the period when the raw material solution supply pump 3 is stopped and only the water supply pump 6 is operated. It will be pushed into the cell 31.

In the present disclosure, supplying cooling water to each of one or more unit cells 31 independently of the raw material solution means that the cooling water is supplied when the water supply pump 6 is operated while the raw material solution supply pump 3 is stopped. It means that it is predominantly supplied into the unit cell 31. That is, in the flow path portion common to the solution supply path and the water supply channel, the volume of this common flow path (the maximum value of the volume at which the residual raw material solution can be extruded) is the average flow rate of the water supply pump 6 (in the on period and the off period). It is permissible on condition that the volume is such that the average residence time (time required for the common flow path to be completely replaced by the cooling water due to the inflow of the cooling water) is 2 to 12 seconds at the average flow rate).

The diameters of the individual raw material supply passages 30e and the individual cooling water supply passages 37e are not particularly limited, and the number thereof may be one or more per unit cell, but in general, the total opening area of each is limited. The number and size can be set so as to be a predetermined ratio of the effective single-sided area of the electrode.

The ceiling portion 20a of the frame structure is provided with an individual electrolytic solution discharge port 26 for discharging the electrolytic solution generated by electrolysis for each unit cell 31. The diameter and number of the individual electrolyte discharge ports 26 are not particularly limited, but it is preferable that the number of the individual electrolyte discharge ports 26 per unit cell is single depending on predetermined conditions. The individual electrolytic solution discharge port 26 can be provided with a structure (electrolyte solution assembly / discharge structure) for equalizing the discharge of the electrolytic solution from each of the discharge ports. The predetermined condition regarding the number of individual electrolytic solution discharge ports 26 described above is related to the electrolytic solution collecting / discharging structure, and the individual electrolytic solution discharging port 26 is a unit cell when the electrolytic solution collecting / discharging structure is not provided. It is preferable that one is provided for each unit, and in that case, the individual electrolyte discharge port 26 for each unit cell becomes an opening 28 that communicates with the outer tank as it is.

When a plurality of individual electrolytic solution discharge ports 26 are provided for each unit cell, it is preferable to provide an electrolytic solution collecting / discharging structure for uniform discharge of the electrolytic solution from each of the discharging ports 26. The embodiment shown in FIG. 2 shows a case where the electrolytic solution collecting / discharging structure 28a is provided, and the electrolytic solution collecting / discharging structure 28a is for collecting the electrolytic solutions from the individual electrolytic solution discharging ports 26. The common discharge flow path 28b and the opening (common discharge port) 28 for discharging the collected electrolytic solution are provided. When there are a plurality of individual electrolyte discharge ports 26, the electrolyte is discharged to the outer tank 32 through one discharge port, while the raw water in the outer tank 32 easily flows back from another discharge port, and the backflow of this raw water is likely to occur. This is to control the backflow of the raw water because it may affect the properties of the slightly acidic hypochlorous acid water 36 finally obtained. By providing the electrolytic solution collecting / discharging structure 28a, even when there are a plurality of individual electrolytic solution discharging ports 26, the backflow of raw water from the outer tank 32 to the inner tank 20 can be suitably reduced.

Further, the amount of cooling water supplied to one or more unit cells 31 is preferably an average residence time of 200 to 750 seconds per unit cell (in the unit cell due to the inflow of cooling water) from the viewpoint of sufficient cooling. The average flow rate is preferably 600 seconds or less, and more preferably 550 seconds or less. The above-mentioned range of the amount of cooling water is a preferable range from the viewpoint of stably generating electrolyzed water having predetermined properties from the time of restart and preventing deterioration of the electrode in a high temperature state. , Not limited to this range. If the cooling water is supplied with an average residence time of about 3000 seconds, a certain effect on the deterioration of the electrodes is expected, and depending on the conditions such as hardness, the average residence time is less than 200 seconds. May be good. Therefore, as long as the conditions allow, the cooling water can be supplied with an arbitrary average residence time.

The number of millimole of pure hydrogen chloride (hydrogen chloride supply amount) supplied per unit volume of a unit cell in a unit time prevents a decrease in power efficiency due to a power loss and a decrease in a chlorine conversion rate. From this point of view, it can be preferably 0.0006 mMol / hmm ³ or more, 0.013 mMol / hmm ³ or less, more preferably 0.0013 mMol / hmm ³ or more, and 0.0063 mMol / hmm ³ or less.

The raw material solution supplied to each unit cell 31 via the individual raw material supply path 30e is electrolyzed while moving vertically upward in the unit cell 31, and the electrolytic solution passing through each of the unit cells 31 is an individual electrolytic solution. It is discharged from the discharge port 26. Chloride ions contained in the raw material are electrolyzed while passing through each unit cell 31, and finally converted into HOCl hypochlorous acid and a small amount of hydrogen chloride HCl.

In the embodiment provided with the electrolytic solution collecting / discharging structure 28a, the plurality of individual electrolytic solution discharging ports 26 are formed in the upper portion thereof, communicate with the common discharging flow path 28b connected to the opening 28, and pass through the gap. The electrolytic solution that has been generated is discharged from the opening 28. The electrolytic solution is discharged from the opening 28 formed in the inner tank 20 in a larger area than the individual electrolytic solution discharge port 26 through the common discharge flow path 28b to the portion in the outer tank 32 through which the raw water flows. On the other hand, in the embodiment in which the electrolytic solution collecting / discharging structure 28a is not provided, the plurality of individual electrolytic solution discharging ports 26 are located in the portion where the electrolytic solution passing through the gap is directly circulated in the outer tank 32. Discharge.

The electrolytic solution is discharged into the outer tank 32 through the opening 28, and is mixed with the raw water flowing down there. The electrolytic solution is diluted with raw water in the outer tank 32 and then discharged as slightly acidic hypochlorous acid water 36 from the outlet 35.

The above-mentioned multipolar electrode makes it possible to provide appropriate electrolysis characteristics at the anode and cathode while simplifying the structure of the electrode, improving the electrolysis efficiency and improving the production efficiency of slightly acidic hypochlorous acid water. It has the advantage that it can be improved.

FIG. 4 is a diagram illustrating how to attach the electrolytic cell unit 60 to the outer tank 32 according to the present embodiment. FIG. 5 is a perspective view of the electrolytic cell unit 60 according to the present embodiment. Note that the directions of the line of sight are different between FIGS. 5 (A) and 5 (B), as shown by the arrangement of the arrows A and B. As shown in FIGS. 4 and 5, the electrolytic cell unit 60 is connected to the inner tank 20 via the inner tank 20, the two power feeding wirings 29a attached to the upper surface of the inner tank 20, and the connecting portions 30c and 37c, respectively. It is configured to include the pipes 30b and 37b to be connected. As shown in FIG. 4, the electrolytic cell unit 60 is fitted into the outer tank 32 from the upper opening of the outer tank 32, covered with the outer tank lid 39 provided with each terminal and a supply port, and sealed.

Hereinafter, a production method for producing slightly acidic hypochlorous acid water using the double-shell structure electrolytic cell 40 according to the above-described embodiment will be described with reference to FIG. The control shown in FIG. 6 corresponds to the case where acclimation is not performed. FIG. 6A shows a control flow on the raw material solution supply pump 3 side, and FIG. 6B shows a control flow on the water supply pump 6 side performed asynchronously with the raw material solution supply pump 3.

The manufacturing method shown in FIG. 6 is started from step S100, and in step S101, the control device 43 opens the tap for raw water. In step S102, the control device 43 energizes the power supply device and starts applying an electrolytic current between the electrodes.

In step S103, the control device 43 determines whether or not the pump start condition is satisfied. For example, the control device 43 satisfies the pump start condition by reading the measured value of the current measured by the current measuring unit 42 and determining whether or not the measured value of the current is less than a preset lower limit value. It can be determined whether or not. In step S103, for example, when the lower limit value is exceeded and it is determined that the pump starting condition is not satisfied (NO), step S103 is looped. On the other hand, in step S103, for example, when it is less than the lower limit and it is determined that the pump start condition is satisfied (YES), the control proceeds to step S104. In step S104, the control device 43 starts the raw material solution supply pump 3 and, if necessary, a dilution pump (when diluting the raw material solution in advance), and starts supplying the raw material solution.

In step S105, the control device 43 determines whether or not the pump stop condition is satisfied, and waits until the condition is satisfied (during NO). For example, the control device 43 reads the measured value of the current measured by the current measuring unit 42 and determines whether or not the measured value exceeds a preset upper limit value, thereby satisfying the pump stop condition. Can be determined. If it is determined in step S105 that the pump stop condition is satisfied by exceeding, for example, a set upper limit value (YES), control proceeds to step S106. In step S106, the control device 43 stops the raw material solution supply pump 3 and, if necessary, the dilution pump (when diluting the raw material solution in advance), stops the supply of the raw material solution, and returns to step S103.

Focusing on the electrolytic solution, the following processing is performed by the operation of the raw material solution supply pump 3 described above. By the pump operation, the raw material solution is supplied to the unit cell 31 between the plurality of electrodes 24 provided in the inner tank 20 so as to face each other. While the raw material solution is passing through the unit cell 31, the chlorine ions in the raw material are electrolytically oxidized on the anode surface of the electrodes 24 and the cathode in response to the current applied between the plurality of electrodes 24. Hydrogen gas is generated on the surface. The electrolytic solution mixed with the electrolytically generated hydrogen gas is discharged from the unit cell 31 between the electrodes 24 and diluted with diluting water in the outer tank 32. The slightly acidic hypochlorous acid water 36 generated is discharged from the double-shell structure electrolytic cell 40 via the outlet 35 while separating the excess gas.

Further, on the water supply pump 6 side that operates asynchronously with the raw material solution supply pump 3, the steps S200 to S203 shown in FIG. 6B are controlled.

In step S201, the control device 43 determines whether or not the water supply condition of the cooling water is satisfied. Here, the water supply condition of the cooling water can be conditioned on the fact that electrolysis is being performed first. Further, as described above, the acclimatization process may be performed at the start of electrolysis, and in the acclimatization process, when the measured value of the current is low, the voltage rise period in which the applied voltage is increased so as to be in a state where electrolysis is easier is performed. be. On the other hand, the supply of cooling water cools the space of the unit cell 31 and also causes a side effect of diluting the raw material solution in the unit cell 31 and lowering the conductivity. For this reason, it is not desirable to supply cooling water that causes a side effect of making it more difficult for current to flow during acclimation boosting. Therefore, it is preferable that the water supply condition of the cooling water is not during acclimation and boosting. That is, the control device 43 is in the process of electrolysis, and during a period other than the step of boosting the voltage of the power supply device 41 based on the measured value of the current by the power supply device 41 starting from the start of electrolysis (during acclimatization boosting). It is preferable to supply the water supply pump 6 with cooling water.

If it is determined in step S201 that the water supply condition of the cooling water is satisfied (YES), the control proceeds to step S202. In the process S202, the control device 43 operates the water supply pump 6 and returns the control to the process S201 after an appropriate waiting time. On the other hand, if it is determined in step S201 that the water supply condition of the cooling water is not satisfied (NO), the process is branched to step S203. In the process S203, the control device 43 stops the water supply pump 6 and returns the control to the process S201 after an appropriate waiting time.

Hereinafter, the acclimatization process at the start of electrolysis described above will be described with reference to FIG. 7. The control shown in FIG. 7 shows a control flow on the raw material solution supply pump 3 side, which is performed asynchronously with the water supply pump 6 side.

The manufacturing method shown in FIG. 7 is started from step S300, and in step S301, the control device 43 opens the tap for raw water. In step S302, the control device 43 energizes the power supply device 41 and starts applying an electrolytic current between the electrodes. In step S303, the control device 43 measures the flow rate of the raw water at the timing when the power supply device 41 is energized, and calculates the target current value, the upper limit current value, and the lower limit current value at the time of acclimatization.

In step S304, the control device 43 starts a voltage increase process in which the applied voltage of the power supply device 41 is gradually increased at regular intervals. In step S305, the control device 43 determines whether or not the measured value of the current has reached the target current value, and continues boosting until the target current value is reached (during NO). If it is determined in step S305 that the target current value has been reached (YES), control proceeds to step S306. The period from the start of voltage rise in step S304 to the determination that the target current value has been reached in step S305 is the acclimation boosting period. As shown in FIG. 7, while it is determined in step S305 that the target current value has not been reached (during NO), control of step S314 is advanced to determine whether or not the set maximum voltage has been reached. If the target current value is not reached even if the set maximum voltage is reached (YES in S314), the control may be advanced to the step S306.

In step S306, the control device 43 determines whether or not the measured value of the current is below the upper limit current value. If it is determined in step S306 that the current value is below the upper limit (YES), control proceeds to step S307. In step S307, the control device 43 keeps the voltage constant even when the raw material solution supply pump 3 is started. In step S308, the control device 43 determines whether or not the measured value of the current exceeds the upper limit current value, and waits until the upper limit current value is exceeded (during NO). If it is determined in step S308 that the upper limit current value is exceeded (YES), control proceeds to step S309. In step S309, the control device 43 starts the voltage drop at a predetermined rate while stopping the raw material solution supply pump 3, and advances the control to step S311. On the other hand, if it is determined in step S306 that the measured value of the current does not fall below the upper limit current value (NO), the process proceeds to step S310. In the step S310, the control device 43 starts the voltage drop at a predetermined rate while the raw material solution supply pump 3 is not started, and advances the control to the step S311.

In step S311, the control device 43 determines whether or not the voltage currently applied has reached a predetermined set voltage. If it is determined in step S311 that the set voltage has not been reached (NO), control proceeds to step S312. In step S312, the control device 43 determines whether or not the measured value of the current is below the lower limit current value, and loops to step S311 until it falls below the lower limit current value (during NO). On the other hand, when it is determined in step S312 that the measured value of the current is lower than the lower limit current value (YES), the control is returned to step S307, and the raw material pump is started and the voltage is held in step S307. In this way, starting and holding the voltage of the raw material solution supply pump 3 and stopping and dropping the voltage of the raw material solution supply pump 3 are repeated, and when it is determined in step S311 that the set voltage has been reached (YES), step S313. Then, it shifts to normal operation. The overcurrent detection is not performed until the above normal operation is performed.

Although not shown in FIG. 7, in the acclimatization step-down step, when the condition that the measured current value exceeds the set current value and is maintained for the set time or longer under a constant voltage is satisfied, the step step-down control is further performed. You may.

As described above, the raw material solution supply pump 3 is controlled based on the measured value of the current by the power supply device 41. Therefore, when the cooling water is supplied in synchronization with the raw material solution supply pump 3, the raw material solution supply pump 3 is operated in response to the decrease in the measured value of the current by the power supply device 41. , The cooling water that causes the side effect of dilution that makes it difficult for the current to flow will be supplied. Therefore, it is desirable that the operation of the water supply pump 6 is asynchronous with the operation of the solution supply pump. Further, from the viewpoint of constantly cooling the inside of the inner tank 20 with cooling water while performing electrolysis, it is preferable that the water supply pump 6 supplies the cooling water intermittently or continuously / quantitatively at regular intervals. The water supply pump 6 is not particularly limited, but from the viewpoint of intermittently supplying cooling water, a diaphragm pump having a single pump head or the like can be used.

FIG. 8 is a chart showing control signals of the raw material solution supply pump 3 and the water supply pump 6 according to a preferred embodiment. As a reference, FIG. 8 shows a control signal of the dilution pump that operates in synchronization with the raw material solution supply pump 3. As shown in FIG. 8, the raw material solution supply pump 3 and the dilution pump are turned on and off at arbitrary timings in response to the measured value of the current. On the other hand, in a preferred embodiment, the water supply pump 6 is intermittently driven by the on period T2 in the cycle T1 as shown in FIG.

Hereinafter, the advantages of the method of supplying the cooling water to the unit cell 31 independently of the above-mentioned raw material solution will be described with reference to FIGS. 9 to 11.

FIG. 9 is a graph showing the temperature change measured at the discharge port of the electrolytic solution (gas) in the rectangular electrolytic cell.

Here, the process leading to the temperature measurement will be briefly described. Until now, under specific conditions that depend on the quality of raw water and usage conditions, operational anxiety due to abnormal electrolysis, deviation from the target range of effective chlorine concentration and pH, and shortening of the life of the electrode (and thus the electrolytic cell) In some cases, problems such as (deterioration symptoms appear in a shorter time than expected) may occur. In particular, it is an electrolytic cell in which a plurality of discharge ports are provided for each unit cell, and the above-mentioned electrolyte collection / discharge structure 28a is provided. In some cases, the overcurrent state in which the set current exceeded the set current unintentionally continued even after the treatment, and the phenomenon of shortening the life of the electrode occurred. Here, the deterioration of the electrode will be described in detail later, but as shown by the alternate long and short dash line in FIG. 9, when the electrolysis is temporarily stopped and the electrolysis is restarted after a certain period of time, the expected current ( It appears in the form that the current value before the electrolysis is stopped) cannot be obtained. In such a case, the acclimatization process is typically performed. In addition, the above-mentioned unintentionally continuing overcurrent state causes an excessive supply of the raw material solution in an attempt to pass a current, and after reaching the set value, the current does not decrease even if the supply is stopped, and an overcurrent is detected and an error occurs. Is an event that causes.

On the other hand, when the electrolyte collecting / discharging structure 28a is removed from the electrolytic cell, the above-mentioned unintentionally continuing overcurrent state and shortening of the life of the electrode are somewhat alleviated, while being generated under specific conditions. In some cases, the properties of the slightly acidic hypochlorous acid water were affected. In particular, when the target is a high effective chlorine concentration, the pH of the obtained slightly acidic hypochlorous acid water may be lower than expected, or conversely, the pH of the slightly acidic hypochlorite water may be kept within the appropriate range. Attempt, it was sometimes difficult to raise the effective chlorine concentration to the target.

In order to investigate the cause of the deterioration of the electrode, the deterioration state of the electrode surface (at the inlet of the raw material solution and the outlet of the electrolytic solution, the iridium oxide and the platinum film are consumed and the titanium base material is dissolved) and the electrolytic solution. Since the outlet is always in contact with a harsh liquid such as a mixture of chlorine gas, hypochlorite and hydrochloric acid, it is possible that the local concentration of current due to the asymmetrical hydrochloric acid concentration accelerates electrode wear. I was suspected. Therefore, we created a single-pole transparent electrolytic cell and tried to measure the current distribution and hydrochloric acid in the electrolytic cell. The result was that there was no bias in the current density that would affect the whole, and it was uniform throughout the electrode plate. The measured value of the internal hydrochloric acid concentration did not become an extremely high value. On the other hand, it was found that the temperature of the side surface of the electrolytic cell was higher than expected. From the above background, we focused on the temperature at the center of the electrolytic cell, and conducted an experiment to measure the temperature of the electrolytic cell and verify the effect of adding water to the cooling water.

The graph of the temperature change shown in FIG. 9 was obtained by using a HOCL 0.96t rectangular electrolytic cell (inner tank) manufactured by Micro Acid Research Institute Co., Ltd. with a thermocouple provided in the vicinity of the electrolyte and gas discharge ports. Is. The rectangular electrolytic cell was removed from the outer tank, and electrolysis was performed under the conditions of taking it out of the water tank and submerging it in the water tank. Cooling water and 9% hydrochloric acid (raw material solution) were supplied to the internal flow path in the electrolytic cell through a separate port, the power supply device was energized, and the output and current value of the thermocouple were recorded. The experimental conditions are changed with the passage of time, and the numerical value of the outlet temperature at the time when the temperature change is stable is shown in FIG. 9 with a thick vertical line indicating the stable time of each condition. ..

The electrolytic conditions were all a set voltage of 33 V and a set current of 5 A. The temperature of the cooling water was 20 ° C. Condition 1 is that the rectangular electrolytic cell is taken out of the water tank and energized without adding water to the unit cell. Condition 2 is that the cooling water is moderately hydrated and the rectangular electrolytic cell is taken out of the water tank to be energized. Condition 3 is that the cooling water is added in a large amount and the rectangular electrolytic cell is taken out of the water tank to be energized. Condition 4 is the same as the condition of Condition 3, in which a large amount of cooling water is added and the rectangular electrolytic cell is submerged in the water tank to energize the water. Condition 5 is that the rectangular electrolytic cell is submerged in a water tank and energized without adding water to the cooling water.

As shown in FIG. 9, the measurement showed that the temperature was 79 ° C. under condition 1, 64 ° C. under condition 2, 57 ° C. under condition 3, 46 ° C. under condition 4, and 55 ° C. under condition 5. The above condition 1 can be considered to correspond to the cell temperature in the central portion of the multilayer electrolytic cell in which heat does not flow in and out. The above conditions 2 and 3 show the cooling effect by adding water to the cooling water, and the condition 4 shows the effect of jacket cooling when compared with the condition 3. Condition 5 corresponds to a condition in which the jacket is cooled in the outer tank in a conventional double-shell structure electrolytic cell in which the cooling water is not hydrated.

In FIG. 9, what should be noted is that it suggests that the temperature may reach about 79 ° C. in the center of the cell, and that jacket cooling has the effect of cooling the electrolytic solution to about 66 ° C. This is a suggestion. Since the inside of the electrolytic cell is in a mixed state of chlorine, hydrochloric acid and hypochlorous acid and has high oxidizing power and dissolving power, it has been found that the deterioration of the electrode material described above is likely to proceed in combination with this temperature state.

On the other hand, if the electrolytic solution collecting / discharging structure 28a attached for the purpose of homogenization is removed, the occurrence of the unintentionally continuing overcurrent state and the occurrence of the electrode deterioration event are suppressed, while the pH and the like are suppressed. The properties are affected by the raw water flowing back from the outer tank into the electrolytic cell, which cools the inside of the electrolytic cell, but changes the solution state inside the unit cell 31, and the raw material solution supply pump 3 according to the current value. It was found that the cause was that it affected the electrolytic state in combination with the feedback control.

Then, after attaching the electrolytic solution collecting / discharging structure 28a so that the backflow of raw water to the electrolytic cell is unlikely to occur (or having a single discharge port), electrolysis is performed independently of the raw material solution. By providing a path for supplying cooling water into each unit cell of the tank, it is possible to efficiently cool the inside of the electrolytic cell including the central part, and the aqueous solution within the target property range can be electrolyzed normally. It was found that stable production is possible and the life of the electrode and the electrolytic cell is optimized.

FIG. 10 is a graph showing the time change of the current value at the time of restart after stopping the electrolysis during stable operation. Note that FIG. 10 corresponds to the case where the acclimation process is not performed. Using 9% hydrochloric acid as the raw material solution, HOCL 0.96t manufactured by Micro Acid Research Institute Co., Ltd. was operated continuously for 2 hours under electrolytic conditions of 5A, electrolysis was stopped when the internal temperature became stable, held for 30 minutes, and then restarted. The time change of the current was recorded. The electrolytic cell had 12 cells, and the volume per cell was 22.8 ml. In the absence of water in the cooling water (that is, in the case of "no water"), the current immediately before the stop could not be maintained, and there was a tendency for the current to gradually rise over several minutes. Since the cathode side is in a reduced state during electrolysis, it is considered that the oxidation reaction does not proceed, but it is presumed that deterioration such as oxidation of the titanium base material occurred during the shutdown at a high temperature state. In particular, this tendency was exacerbated when left overnight (12 hours).

On the other hand, in the case of the addition of cooling water (“weak water” and “strong water”), the recovery to the current immediately before the stop was quick, and the higher the water intensity, the better. In the graph of FIG. 10, “weak water” is a watering condition (welco) such that the period T1 shown in FIG. 8 is 10 seconds and the on period T2 is 5 seconds, and the average residence time is about 720 seconds per cell. It is a pump manufactured by the same company (WPX1-P3.2M4-WM4-B) with a setting of 16V). The "water addition strength" is a water addition condition (setting of 20 V) so that the cycle T1 is 10 seconds and the on period T2 is 5 seconds, and the average residence time is about 540 seconds per cell. Under the condition of "strong water addition", the set current reaches 5.5A immediately after restart (about 10 seconds later), whereas in "weak water addition", the set current reaches 5.5A with a slight delay, while the set current reaches 5.5A. Under the condition of "no water addition", the reaction at the time of restart was further worsened. In addition, although the setting of "more water" changed to an overcurrent, the current was reduced by the watering of the cooling water after that (after 35 seconds), and the normal operating state was restored. In other settings, the current value did not return, but returned to the set current value by supplying hydrochloric acid by operating the raw material solution supply pump. In the time range shown in FIG. 10, the "weak water" recovered only to about 4.5 A, but in reality, the current gradually increased and reached a set current of about 5.5 A.

The flow rate of "strong water addition" in FIG. 10 is converted to 1800 ml / hr, which is equivalent to 7-fold dilution when added to the raw material solution in synchronous operation, and the concentration becomes too low, so that the required current is applied. I can't expect to get it. Therefore, it is preferable to separate the flow paths of the raw material solution (hydrochloric acid) and the cooling water.

Even if the above-mentioned electrode deterioration occurs once, it does not deteriorate again without interrupting the set current maintained before restarting by performing electrolysis while adding cooling water next time. It was confirmed that the behavior was similar to that of. That is, it is shown that the deterioration of the electrode can be recovered, and it is expected that a stable current can be secured without performing the acclimatization treatment performed when the above-mentioned electrode is deteriorated.

FIG. 11 is a graph showing changes in effective chlorine concentration and pH at the time of restart after stopping electrolysis during continuous operation. The continuous operation time was set to 2 hours, and the stop time until restart was set to 15 minutes. As shown in FIG. 11, in the case of no water addition, excess hydrochloric acid is supplied because sufficient current is not secured at the time of restart, and a slightly acidic hypochlorous acid water having a high chlorine concentration and a low pH is produced over 20 minutes. rice field. On the other hand, because it is not cooled, the temperature rises, and when the temperature rises, the conductivity rises and the current is more likely to flow (stopped in a good state, and then the electrolyte temperature drops, so the conductivity also drops). The supply amount of raw material hydrochloric acid to be supplied decreases. Then, the concentration of chlorine produced becomes low and the pH also rises. On the other hand, when there is water in the cooling water, sufficient hydrochloric acid is supplied and the pH is stabilized at 6.3. It was shown that it was cooled by water (because it was kept at a necessary and sufficient amount of electrolyte concentration in the electrolytic cell immediately after restarting), stable chlorine gas was generated, and a sufficient effective chlorine concentration could be obtained. There is.

According to the embodiment described above, the electrolytic cell is effectively cooled, the life of the electrode and the electrolytic cell is optimized, and an aqueous solution within the target property range is stably generated by normal electrolysis operation. It is possible to provide a manufacturing apparatus, an electrolytic cell unit and a manufacturing method capable of this.

Further, the supply of the cooling water can play a role not only for cooling but also as a brake when the current becomes too large. By suppressing the temperature rise by cooling, the conductivity can be kept constant, the concentration of the raw material hydrochloric acid can be kept constant, and the decrease in the chlorine concentration can be prevented.

In the above-described embodiment, the case where an aqueous solution of hydrogen chloride or hydrochloric acid is used as the raw material chlorine ion-containing solution is exemplified, but the solution is not limited to hydrochloric acid, and is a solution of sodium chloride, potassium chloride or the like. It may be a mixture thereof, or a chlorine ion-containing solution in which one or more substances selected from the group consisting of hydrogen chloride, sodium chloride and potassium chloride may be dissolved. Moreover, although the production of hypochlorous acid water has been described, it can be generally extended to an aqueous solution containing at least free hypochlorous acid.

Although the present invention has been described above with embodiments, the present invention is not limited to the above-described embodiments, and as long as the present invention exerts its actions and effects within the range of embodiments that can be inferred by those skilled in the art. , Is included in the scope of the present invention.

1 ... raw material tank, 2 ... raw material supply pipe, 3 ... raw material solution supply pump, 4 ... cooling water, 5 ... water supply pipe, 6 ... water supply pump, 20 ... inner tank, 24 ... electrode, 26 ... individual electrolyte discharge port, 28 ... opening, 29 ... power supply terminal, 30 ... raw material supply port, 31 ... unit cell, 32 ... outer tank, 33 ... raw water supply port, 34 ... raw water, 35 ... outlet, 36 ... slightly acidic hypochlorous acid water, 37 ... Cooling water supply port, 39 ... Outer tank lid, 40 ... Double shell structure electrolytic tank, 41 ... Power supply device, 42 ... Current measurement unit, 43 ... Control device, 50 ... Manufacturing device, 60 ... Electrolyzer tank unit

Japanese Unexamined Patent Publication No. 2019-198820

Claims (12)

With an electrolytic cell
With a plurality of electrodes provided in the electrolytic cell,
One or more unit cells formed between the electrodes in the electrolytic cell, and
A solution supply path for supplying the raw material solution to the electrolytic cell and
A water supply channel that supplies cooling water to each of the one or more unit cells independently of the raw material solution.
A discharge port for discharging the electrolytic solution generated by electrolysis of the raw material solution from the one or more unit cells.
A power supply device that allows current to flow between the plurality of electrodes,
A device for producing an aqueous solution. A solution supply pump connected to the solution supply path and
The manufacturing apparatus according to claim 1, further comprising a water supply pump connected to the water supply channel and operating asynchronously with the solution supply pump. The water supply pump is characterized in that the cooling water is supplied intermittently or continuously / quantitatively, and the manufacturing apparatus is used.
The manufacturing apparatus according to claim 2, further comprising a control device that controls the operation of the solution supply pump based on the measured value of the current by the power supply device. The control device is attached to the water supply pump during the period during electrolysis and during the period excluding the step of boosting the voltage of the power supply device based on the measured value of the current by the power supply device starting from the start of electrolysis. The manufacturing apparatus according to claim 3, wherein the cooling water is controlled to be supplied to the cooling water. The method according to any one of claims 2 to 4, wherein the water supply pump supplies cooling water through the water supply channel at a flow rate having an average residence time of 750 seconds or less per unit cell. manufacturing device. One outlet is provided for each unit cell, or
A plurality of the discharge ports are provided for each unit cell, and the manufacturing apparatus is assembled with a common discharge flow path for collecting the electrolytic solution from the discharge port of the one or more unit cells. The manufacturing apparatus according to any one of claims 1 to 5, further comprising a common discharge port for discharging the electrolytic solution in the electrolytic cell. The water supply channel supplies the cooling water independently of the solution supply path to the inlet of each of the one or more unit cells, or the solution supply channel to the front stage of the inlet of each of the one or more unit cells. The manufacturing apparatus according to any one of claims 1 to 6, which is independent and shares a part of the flow path with the solution supply path in the previous stage. A dilution that is provided on the outside of the electrolytic cell so as to surround the electrolytic cell, communicates with the electrolytic cell, dilutes the electrolytic solution discharged from the electrolytic cell with raw water, and cools the electrolytic cell with the raw water. With a tank,
The manufacturing apparatus according to any one of claims 1 to 7, further comprising an outlet for taking out a diluted aqueous solution from the dilution tank. With an electrolytic cell
With a plurality of electrodes provided in the electrolytic cell,
One or more unit cells formed between the electrodes in the electrolytic cell, and
A solution supply path for supplying the raw material solution to the electrolytic cell and
A water supply channel for supplying cooling water to each of the one or more unit cells independently of the raw material solution.
An electrolytic cell unit including an discharge port for discharging an electrolytic solution generated by electrolysis of the raw material solution from the one or more unit cells. The electrolytic cell unit according to claim 9, wherein the water supply channel and the solution supply channel are connected to a water supply pump and a solution supply pump that operate asynchronously with each other, respectively. A step of supplying the raw material solution to each of one or more unit cells provided in the electrolytic cell via the solution supply path, and
A step of passing a current between a plurality of electrodes provided in the electrolytic cell and electrolyzing the raw material solution supplied to each unit cell to generate an electrolytic solution.
A step of supplying cooling water to each of the one or more unit cells via a water supply channel independently of the raw material solution.
The step of discharging the electrolytic solution from each of the one or more unit cells, and
A method for producing an aqueous solution, which comprises a step of diluting the discharged electrolyte solution with raw water. The step of supplying the cooling water is
The manufacturing method according to claim 11, wherein the water supply pump is controlled asynchronously with the raw material pump that supplies the raw material solution through the solution supply path.

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