US20160194770A1

US20160194770A1 - Electrolytic apparatus and method of producing electrolyzed water

Info

Publication number: US20160194770A1
Application number: US15/068,023
Authority: US
Inventors: Masahiro Yokota; Hideo Oota; Hisashi Chigusa; Hidemi Matsuda
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2014-09-22
Filing date: 2016-03-11
Publication date: 2016-07-07
Also published as: WO2016047161A1; CN106460206A

Abstract

According to one embodiment, an electrolytic apparatus includes an electrolytic cell including an anode chamber, an intermediate chamber, a cathode chamber, separating membranes, an anode in the anode chamber, and a cathode in the cathode chamber, a water supply portion which supplies water to the anode and cathode chambers and intermittently changes a water supply and discharge amount, an electrolyte fluid supply portion which supplies and discharges an electrolyte fluid to the intermediate chamber, and a controller which applies potential to the anode and the cathode and electrolyzes the electrolyte fluid in a state where the water supply and discharge amount is small or in a water static state in at least one of the anode and the cathode chambers.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of PCI Application No. PCT/JP2015/054981, filed Feb. 23, 2015 and based upon and claiming the benefit of priority from Japanese Patent Application No. 2014-192939, filed Sep. 22, 2014, the entire contents of all of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an electrolytic apparatus and a method of producing electrolyzed water.

BACKGROUND

An electrolyzed water production apparatus which comprises a three-compartment electrolytic cell has been used as an apparatus for producing, for example, ionized alkaline water, ozone water or aqueous hypochlorous acid. The casing of the three-compartment electrolytic cell is divided by separating membranes comprising a cation exchange membrane and an anion exchange membrane into three chambers. The three chambers are an anode chamber, an intermediate chamber and a cathode chamber. In the anode chamber and the cathode chamber, an anode and a cathode are provided respectively.
In this type of electrolyzed water production apparatus, for example, a salt water is supplied to the intermediate chamber, and water is supplied to the cathode chamber and the anode chamber on the left and right. The salt water in the intermediate chamber is electrolyzed by the cathode and the anode. In this manner, aqueous hypochlorous acid is produced from the gaseous chlorine produced in the anode chamber. In the cathode chamber, aqueous sodium hydroxide is produced. The produced aqueous hypochlorous acid is used as sterilizing water. The aqueous sodium hydroxide is used as washing water.
However, the anion exchange membrane which separates the intermediate chamber from the anode chamber lacks durability relative to the gaseous chlorine produced by the anode, acid and alkali. In the three-compartment electrolytic cell explained above, a space may be produced between the electrodes and the ion-exchange membranes by the difference in water pressure produced between the anode chamber and/or the cathode chamber and the intermediate chamber when delivering water and an electrolyte fluid to the electrolytic cell. Thus, the electrolytic property may change.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a structure of an electrolytic apparatus according to a first embodiment.

FIG. 2 is a schematic diagram showing a structure of an electrolytic apparatus according to a second embodiment.

FIG. 3 is a schematic diagram showing a structure of an electrolytic apparatus according to a third embodiment.

FIG. 4 is a schematic diagram showing a structure of an electrolytic apparatus according to a fourth embodiment.

DETAILED DESCRIPTION

Various embodiments will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment, an electrolytic apparatus comprises an electrolytic cell comprising: a first separating membrane which separates an anode chamber from an intermediate chamber through which an electrolyte fluid flows, a second separating membrane which separates the intermediate chamber from a cathode chamber; an anode which faces the first separating membrane and is provided in the anode chamber, and a cathode which faces the second separating membrane and is provided in the cathode chamber; a water supply portion which supplies water to the anode chamber and the cathode chamber and intermittently changes a water supply and discharge amount to at least one of the anode chamber and the cathode chamber; an electrolyte fluid supply portion which supplies and discharges an electrolyte fluid to the intermediate chamber; and a controller which applies potential to the anode and the cathode and electrolyzes the electrolyte fluid in a state where the water supply and discharge amount is small or in a water static state in at least one of the anode chamber and the cathode chamber.
In embodiments, common structures are denoted by the same reference numbers and symbols, and overlapping explanations are omitted. The drawings are exemplary diagrams of the embodiments for promoting the understanding. The shape, dimension and ratio in the drawings may be different from those of the actual apparatus. They can be appropriately modified in consideration of the explanations below and the well-known art. In the present application, static water does not necessarily require that the fluid be completely static. Static water may mean that the movement of the fluid is calm to the extent that an ionic substance which does not desire transmission only slightly moves through a porous membrane which does not have ion selectivity within a predetermined time. Static water may mean that the fluid pressure is sufficiently small.

First Embodiment

FIG. 1 schematically shows the whole structure of an electrolytic apparatus 1 according to a first embodiment. As shown in FIG. 1, the electrolytic apparatus 1 comprises a three-compartment electrolytic cell 10. The electrolytic cell 10 comprises, for example, a casing which has the shape of a substantially rectangular box. An inner space of the casing is divided by a first separating membrane 17 a and a second separating membrane 17 b into an intermediate chamber 18 a, an anode chamber 18 b and a cathode chamber 18 c. The anode chamber 18 b and the cathode chamber 18 c are allocated on both sides of the intermediate chamber 18 a. In the present embodiment, the first separating membrane 17 a and the second separating membrane 17 b are formed by porous membranes which have the same structure. In the anode chamber 18 b, an anode 15 a is provided in proximity to the first separating membrane 17 a. In the cathode chamber 18 c, a cathode 15 b is provided in proximity to the second separating membrane 17 b.
The intermediate chamber 18 a comprises a first inlet 14 a into which an electrolyte fluid flows and a first outlet 14 b which discharges the electrolyte fluid which had passed through the intermediate chamber 18 a. The anode chamber 18 b comprises a second inlet 12 a into which electrolyzed water flows and a second outlet 12 b which discharges the electrolyzed water which had passed through the anode chamber 18 b. The cathode chamber 18 c comprises a third inlet 16 a into which electrolyzed water flows and a third outlet 16 b which discharges the electrolyzed water which had passed through the cathode chamber 18 c. In the first embodiment, the capacity of each of the anode chamber 18 b and the cathode chamber 18 c is 500 cc. In general, when the capacity of each of the anode chamber 18 b and the cathode chamber 18 c is 200 cc or greater, the cycle of the intermittent operation explained below does not become short, and thus, control becomes easy.
Basically, the porous membrane constituting each of the first separating membrane 17 a and the second separating membrane 17 b does not have ionic permselectivity. A material which is resistant to gaseous chlorine, such as oxide ceramics, a polyvinylidene fluoride (PVDF) resin and a polytetrafluoroethylene (PTFE) resin, can be selected as the porous membrane. However, to use a porous membrane as the separating membranes of the electrolytic cell, the porous membrane must allow permeation of electrolytes. As a porous membrane does not have ionic selectivity, the selection of a porous membrane which has water permeability is essential. For example, a porous membrane having a water permeability of 10 ml/minute/cm²/MPa can be used.
When a porous membrane which does not have ionic selectivity and has water permeability is used, the porous membrane allows permeation of an unnecessary substance such as a cation unnecessary for the anode chamber 18 b due to the difference in water pressure between the both sides of the separating membrane. Thus, when a salt water is supplied to the intermediate chamber 18 a, unnecessary salinity might be mixed in the anode chamber 18 b or the cathode chamber 18 c depending on the difference in water pressure.
If the above porous membrane having water permeability is used, and the water pressure in the intermediate chamber 18 a relative to the anode chamber 18 b and the cathode chamber 18 c is set to 2 kPa or less, the mixing of salinity in the alkaline water and the acid water produced in the anode chamber 18 b and the cathode chamber 18 c is less than or equal to 300 ppm. Thus, the standard for tap water can be satisfied. Moreover, with use of a porous membrane having a water permeability of 0.1 to 10 ml/minute/cm²/MPa and a pore diameter of 2 to 100 nm, it is possible to prevent mixing of salinity even if the above relative water pressure is 1 to 10 kPa. As the porous membrane having the above water permeability and pore diameter, for example, an ultrafiltration membrane is preferably used.
As explained below, the electrolytic apparatus 1 of the present embodiment is allowed to apply electrolysis in a state where the saline in the intermediate chamber 18 a and the water in the anode chamber 18 b and the cathode chamber 18 c are static. In other words, it is possible to apply electrolysis in a state where the above relative water pressure is zero or sufficiently small. In this case, even if a porous membrane having a water permeability of 0.1 to 100 ml/minute/cm²/MPa and a pore diameter of 2 to 1000 nm is used, it is possible to prevent mixing of salinity. If a porous membrane having a water permeability beyond 100 ml/minute/cm²/MPa is used, unnecessary salinity is mixed due to diffusion even without the difference in water pressure. If a porous membrane having a water permeability of 0.1 ml/minute/cm²/MPa or less is used, electrolytes which are necessary for electrolysis cannot sufficiently pass through the porous membrane. Thus, the desired electrolysis cannot be performed.
In addition to the electrolytic cell 10, the electrolytic apparatus 1 comprises an electrolyte fluid supply portion 20 which supplies an electrolyte fluid, such as saturated saline, to the intermediate chamber 18 a of the electrolytic cell 10, a water supply portion 80 which supplies electrolyzed water, such as water, to the anode chamber 18 b and the cathode chamber 18 c, and a power source 40 which applies a positive potential and a negative potential to the anode 15 a and the cathode 15 b, respectively.
The electrolyte fluid supply portion 20 comprises a salt water tank (electrolyte fluid tank) 70 which produces and stores saturated saline, a supply pipe 20 a which leads saturated saline from the salt water tank 70 to the intermediate chamber 18 a through the first inlet 14 a, a delivery pump 50 provided in the supply pipe 20 a, and a discharge pipe 20 b which circulates the saline which had passed through the intermediate chamber 18 a from the first outlet 14 b to the salt water tank 70 again. As shown in FIG. 1, in the electrolytic apparatus 1 of the first embodiment, saline which is an electrolytic fluid is circulated between the intermediate chamber 18 a and the salt water tank 70 by the delivery pump 50.
An electromagnetic valve 100 (explained later) is provided in a water supply pipe 80 a. The electromagnetic valve 100 and the delivery pump 50 are connected to a controller 500 and controlled by the controller 500. The delivery pump 50 runs for five seconds and then stops for five seconds in cooperation with the electromagnetic valve 100. The delivery pump 50 repeats a cycle of running and stopping every ten seconds. During the running of the delivery pump 50, the water pressure in the intermediate chamber 18 a is approximately 5 to 15 kPa. While the delivery pump 50 is stopped, the water pressure in the intermediate chamber 18 a is zero or infinitesimal. The saline in the intermediate chamber 18 a becomes static as soon as the delivery pump 50 is stopped.
The water delivery pressure of the delivery pump 50 and the opening and closing time of the electromagnetic valve 100 may be determined based on the capacity of the electrolytic cell 10. However, when saturated saline is used as the electrolytic fluid, the amount of consumed electrolytes is extremely small compared to the flow amount. Therefore, the running of the delivery pump 50 does not necessarily conform to the opening time of the electromagnetic valve 100. For example, the running time of the delivery pump 50 may be set to two seconds, and the stopping Lime may be set to eight seconds. The running frequency of the delivery pump 50 may be reduced in such a way that the delivery pump 50 runs only once in two to ten cycles, in other words, at intervals of twenty to a hundred seconds, at a timing when the electromagnetic valve 100 opens.
In the present embodiment, a water delivery state and a static water state are switched by running and stopping the delivery pump 50. However, the essential idea of the embodiment is to control the water pressure by intermittently changing the flow amount. Therefore, the electrolytic apparatus 1 does not necessarily control the water pressure by running and stopping the delivery pump 50. For example, an inverter circuit may be used to change the water delivery amount of the delivery pump 50 and intermittently increase and decrease the water delivery amount. In short, the electrolytic apparatus 1 of the present embodiment only has to intermittently and appropriately change the water pressure.
The water supply portion 80 comprises a water supply source (not shown) which supplies water, the water supply pipe 80 a which leads the water from the water supply source to the lower part of the anode chamber 18 b and the cathode chamber 18 c, the electromagnetic valve 100 provided in the water supply pipe 80 a, a first water discharge pipe 80 h which discharges the water which had passed through the anode chamber 18 b from the second outlet 12 b of the anode chamber 18 b, a second water discharge pipe 80 c which discharges the water which had passed through the cathode chamber 18 c from the third outlet 16 b of the cathode chamber 18 c, and check valves 400 h and 400 c provided in the first water discharge pipe 80 b and the second water discharge pipe 80 c.
The water supply pipe 80 a branches into two after the electromagnetic valve 100. One of the branch pipes is connected to the second inlet 12 a provided in the anode chamber 18 b. The other one is connected to the third inlet 16 a provided in the cathode chamber 18 c.
The check valves 400 b and 400 c are provided in the first water discharge pipe 80 b and the second water discharge pipe 80 c. Therefore, although the produced acid water and alkaline water are discharged when the water pressure in the anode chamber 18 b and the cathode chamber 18 c is higher than a predetermined value, the acid water or the alkaline water does not flow back from the downstream side to the anode chamber 18 b side or the cathode chamber 18 c side. Thus, it is possible to prevent increase in internal pressure of the piping system by the gas produced at the time of electrolysis. Moreover, it is possible to inhibit the produced acid water and alkaline water from flowing back. Further, inclusion of insects and air from outside can be prevented by the check valves 400 b and 400 c.
The standard flow amount of the water supply pipe 80 a, the first water discharge pipe 80 b and the second water discharge pipe 80 c is set to a liter every 5 seconds when the water pressure of the supply source is adjusted to the standard water pressure of 0.2 MPa by a regulator, etc. At this time, flow channels and pipes are structured in such a way that the water pressure in the anode chamber 18 b and the cathode chamber 18 c is 20 to 30 kPa.
The electromagnetic valve 100 repeatedly opens for five seconds and closes for five seconds in cooperation with the delivery pump 50. As a result, one liter of water in the anode chamber 18 b and the cathode chamber 18 c is pushed out for five seconds while the electromagnetic valve 100 opens. Thus, the water in the anode and cathode chambers 18 b and 18 c each having a capacity of 500 cc is completely replaced.
When the electromagnetic valve 100 closes, the water pressure in the anode chamber 18 b and the cathode chamber 18 c is zero or infinitesimal. When the electromagnetic valve 100 opens, the water pressure in the anode chamber 18 b and the cathode chamber 18 c is 20 to 30 kPa. On the other hand, when the delivery pump 50 is stopped, the water pressure in the intermediate chamber 18 a is zero or infinitesimal. When the delivery pump 50 is run, the water pressure in the intermediate chamber 18 a is 5 to 15 kPa. Thus, when the delivery pump 50 is run, the electromagnetic valve 100 always opens, and the water pressure in the anode chamber 18 b and the cathode chamber 18 c is high compared to that in the intermediate chamber 18 a. This prevents mixing of salinity from the intermediate chamber 18 a to the anode chamber 18 b and/or the cathode chamber 18 c through the porous membrane.
In the above explanation, the water which is supplied and discharged to the anode chamber 18 b and the cathode chamber 18 c is intermittently and repeatedly switched between a water delivery state and a static water state by opening and closing the electromagnetic valve 100. However, the essential idea of the electrolytic apparatus of the present embodiment is to intermittently control the water flow pressure. The control of the water flow pressure may be realized by reducing the amount of water supply to the anode chamber 18 b, the cathode chamber 19 c and the intermediate chamber 18 a. For example, the water pressure may be decreased to a predetermined value or less by providing a delivery pump in the water supply pipe 80 a, controlling the water delivery amount of the delivery pump with use of an inverter and reducing the water delivery amount at the time of electrolysis. In other words, an electrolyte fluid may be electrolyzed by applying potential to the anode 15 a and the cathode 15 c in a state where the water supply and discharge amount to the anode chamber 18 b and the cathode chamber 18 c is small.
Now, this specification explains how the electrolytic apparatus 1 having the above structure actually electrolyzes saline and produces an acid water (hypochlorous acid and hydrochloric acid) and an alkaline water (a sodium hydroxide). In the first embodiment, the delivery pump 50, the power source 40 and the electromagnetic valve 100 are controlled by the controller 500. The water supply and discharge, opening and closing of valves and application of potential are appropriately synchronized.
Firstly, the water pressure of the water supply source is set to the standard water pressure of 0.2 MPa by a regulator, etc. The pressure is adjusted in such a way that, for example, the water delivery amount is 24 liters per minute when the electromagnetic valve 100 opens. Subsequently, the running and stopping of the delivery pump 50 is synchronized with the opening and closing of the electromagnetic valve 100. Saturated saline is supplied to the intermediate chamber 18 a of the electrolytic cell 10. Water is supplied to the anode chamber 18 b and the cathode chamber 18 c. Each of the running time of the delivery pump 50 and the opening time of the electromagnetic valve 100 is five seconds. Subsequently, the delivery pump 50 is stopped at the same time as the closing of the electromagnetic valve 100 for five seconds. Thus, the delivery pump 50 is run and stopped for ten seconds as one cycle in synchronization with opening and closing of the electromagnetic valve 100. The cycle is repeated. The cycle of running and stopping the delivery pump 50 and opening and closing the electromagnetic valve may be appropriately adjusted in accordance with the capacities of the anode chamber 18 b, the cathode chamber 18 c and the intermediate chamber 18 a, and/or the water pressure of the water supply source.
In general, when the capacity of each of the anode chamber 18 b and the cathode chamber 18 c is greater than or equal to 200 cc, the above cycle of intermittent operation becomes long, and control can be easily conducted. When the cycle of intermittent operation is long, the apparatus burden is reduced, and the life duration of the delivery pump extends. The amount of water which is delivered by opening the electromagnetic valve 100 is approximately 2000 cc which is twice as large as the sum of capacities of the anode chamber 18 b and the cathode chamber 18 c. In other words, water which is approximately twice as large as the capacity of each chamber is delivered extra for replacement by new water.
While the delivery pump 50 is stopped, and the electromagnetic valve 100 closes, the saline and the water in the intermediate chamber 18 a, the anode chamber 18 b and the cathode chamber 18 c are static. The water pressure in each chamber is zero or sufficiently small. During this period, potential is applied to the anode 15 a and the cathode 15 b for electrolysis. The stopping of the first delivery pump 50, the closing of the electromagnetic valve 100, and the application of potential to the anode 15 a and the cathode 15 b are synchronized by the controller 500. In the above setting, the anode chamber 18 b and the cathode chamber 18 c produce an average of 6 liters per minute of acid water and alkaline water, respectively.
As explained above, the water delivery pressure of the delivery pump 50 is approximately 5 to 15 kPa, and the water delivery pressure of the water supply source is approximately 20 to 30 kPa. Therefore, when saline and water are delivered to the electrolytic cell 10, the water pressure in the anode chamber 18 b and the cathode chamber 18 c is high compared to that in the intermediate chamber 18 a even with use of the porous membranes 17 a and 17 b having water permeability. Thus, salinity is not mixed from the intermediate chamber 18 a to the anode chamber 18 b and/or the cathode chamber 18 c. In addition, when saline and water are static, salinity is not mixed from the intermediate chamber 18 a to the anode chamber 18 b and/or the cathode chamber 18 c since there is no difference in water pressure between the chambers.
While potential is applied to the anode 15 a and the cathode 15 b, and electrolysis is performed, sodium ions electrically separated in the saline which flows into the intermediate chamber 18 a are drawn to the cathode chamber 15 b, pass through the second separating membrane 17 b and flow into the cathode chamber 18 c. In the cathode chamber 18 c, water is electrolyzed, and gaseous hydrogen is produced. Thus, aqueous sodium hydroxide is produced. At the same time, chlorine ions and water are allowed to pass through the water-permeable second separating membrane 17 b. However, since the water pressure in each chamber is zero in electrolysis, the passing amount of chlorine ions is inhibited to a small amount which is less than or equal to the standard for tap water. The aqueous sodium hydroxide and gaseous hydrogen produced in this manner are discharged after passing through the second discharge pipe 80 c from the third outlet 16 b of the cathode chamber 18 c.
The chlorine ions electrically separated in the saline in the intermediate chamber 18 a are drawn to the anode 15 a, pass through the porous membrane 17 a and flow into the anode chamber 18 b. Gaseous chlorine is produced in the anode 15 a. The gaseous chlorine reacts with water in the anode chamber 18 b, thereby producing hypochlorous acid and hydrochloric acid. At the same time, sodium ions and water are allowed to pass through the water-permeable porous membrane 17 a. However, since the water pressure in each chamber is zero in electrolysis, the passing amount of sodium ions is inhibited to a small amount which is less than or equal to the standard for tap water. The acid water (hypochlorous acid and hydrochloric acid) produced in this manner flows out after passing through the first discharge pipe 80 b from the second outlet 12 b of the anode chamber 18 b.
Subsequently, the above steps are repeated. In the above description, this specification explains a series of steps for producing electrolyzed water by using the electrolytic apparatus 1 of the first embodiment.
As explained above, in the electrolytic apparatus 1 of the first embodiment, when each of saline and water is either static or being delivered, the water pressure in the anode chamber 18 b and the cathode chamber 18 c is high compared to that in the intermediate chamber 18 a. Thus, the mixing of salinity from the intermediate chamber 18 a to the anode chamber 18 b and the cathode chamber 18 c is prevented.
In the first embodiment having the above structure, the electrolytic apparatus 1 comprising the three-compartment electrolytic cell uses a porous membrane which has high durability and water-permeability as the first separating membrane and the second separating membrane. Further, the difference in water pressure is removed by the static water in each chamber at the time of electrolysis. While water is delivered, the pressure in the intermediate chamber is negative relative to the other chambers. In this manner, the mixing of salinity in the anode chamber and the cathode chamber is prevented. At the same time, the separating membranes are difficult to be damaged by gaseous chlorine, etc. Thus, stable electrolysis can be performed.

Second Embodiment

FIG. 2 is a schematic diagram showing a structure of an electrolytic apparatus 1 according to a second embodiment. The electrolytic apparatus 1 of the second embodiment further comprises an anode auxiliary chamber 90 b and a cathode auxiliary chamber 90 c in a first water discharge pipe 80 b and a second water discharge pipe 80 c. The capacity of the anode auxiliary chamber 90 b and the cathode auxiliary chamber 90 c is two liters. The other structures of the electrolytic apparatus 1 of the second embodiment are the same as those of the electrolytic apparatus 1 of the first embodiment.
Even when an anode chamber 18 b and a cathode chamber 18 c are compact and have a small capacity, it is possible to deliver a large amount of water at a time by providing the anode auxiliary chamber 90 b and the cathode auxiliary chamber 90 c as described above. Further, the cycle of an intermittent operation such as opening and closing of an electromagnetic valve 100 can be long; for example, thirty seconds (for example, the electromagnetic valve 100 opens for six seconds and closes for twenty four seconds). In sum, in the electrolytic apparatus 1 of the second embodiment, the burden of the apparatus is reduced. The opening and closing cycle of the electromagnetic valve 100 is not limited to thirty seconds, and may be twenty seconds, forty seconds, fifty seconds or sixty seconds. The ratio of opening time to closing time of the electromagnetic valve 100 is not limited to 1:4, and can be appropriately changed. For example, the opening time of the electromagnetic valve 100 may be shortened by increasing the diameter of a water supply pipe 80 a, the first water discharge pipe 80 b and the second water discharge pipe 80 c.
In an intermittent water delivery operation, the water of an electrolytic cell 10 is not appropriately replaced unless a larger amount of water than the capacity of the electrolytic cell 10 is supplied. To replace the electrolyte fluid, an alkaline water and an acid water are produced in such a way that an electrolytic product is more concentrated than the target concentration in anticipation of the extra delivery amount compared to the capacity of the electrolytic cell 10. On the other hand, the acid level of the aqueous hypochlorous acid produced in the anode chamber 18 b is increased if the concentration is excessively increased. The hypochlorous acid is partially changed to gaseous chlorine, and the production efficiency of hypochlorous acid is decreased.
In the second embodiment, the auxiliary chambers are provided in the water discharge pipes separately from the electrolytic cell 10. The auxiliary chambers are communicated with the electrolytic cell 10. Thus, the capacity of combination of the anode chamber 18 b (cathode chamber 18 c) and the anode auxiliary chamber 90 b (cathode auxiliary chamber 90 c) is large. By this structure, extra water to be delivered can be reduced, and the aqueous hypochlorous acid is difficult to be highly concentrated.
In the electrolytic apparatus 1 of the second embodiment having the above structure, the cycle of the intermittent operation is long. Therefore, the burden of the apparatus is reduced, and the electrolytic production efficiency of the anode chamber 18 b is maintained at a high level.
In the second embodiment, similarly to the first embodiment, the electrolytic apparatus 1 comprising the three-compartment electrolytic cell can prevent mixing of salinity in the anode chamber and the cathode chamber, prevent damage of the separating membranes by gaseous chlorine, etc., and perform stable electrolysis.

Third Embodiment

FIG. 3 is a schematic diagram showing a structure of an electrolytic apparatus 1 according to a third embodiment. The electrolytic apparatus 1 of the third embodiment sectionalizes an electrolytic cell 10 into chambers by using water-shielding ion- exchange membranes 13 a and 13 b as first and second separating membranes of the electrolytic cell 10. Further, a delivery pump 50 is not intermittently run, but is always run. In short, saturated saline always flows into an intermediate chamber 18 a. The other structures of the electrolytic apparatus 1 of the third embodiment are the same as those of the electrolytic apparatus 1 of the first embodiment.
In the electrolytic apparatus 1 of the third embodiment, a water pressure of 10 kPa is always applied to the intermediate chamber 18 a. On the other hand, water is intermittently delivered to an anode chamber 18 b and a cathode chamber 18 c by an electromagnetic valve 100. When the water in the anode chamber 18 b and the cathode chamber 18 c is static and at zero pressure, electrolysis is performed. Therefore, at the time of electrolysis, the water pressure in the intermediate chamber 18 a is higher than that in the anode chamber 18 b and the cathode chamber 18 c, and the ion-exchange membranes are attached firmly to the electrodes by the water pressure. Thus, the production efficiency and the water quality stability of alkaline water and acid water are improved.
In general, the water delivery pressure of a low-price pump is low at approximately 10 kPa. In a state where water flows into the anode chamber 18 b and the cathode chamber 18 c, the water pressure in the intermediate chamber 18 a is low. However, in the embodiment shown in FIG. 3, there is no water flow pressure in the anode chamber 18 b or the cathode chamber 18 c at the time of electrolysis. Therefore, electrolysis can be performed in a preferable state where the pressure in the intermediate chamber 18 a is positive relative to the anode chamber 18 b and the cathode chamber 18 c.
In the third embodiment, similarly to the first embodiment, the electrolytic apparatus 1 comprising the three-compartment electrolytic cell can perform stable electrolysis, preventing mixing of salinity in the anode chamber and the cathode chamber.

Fourth Embodiment

FIG. 4 is a schematic diagram showing a structure of an electrolytic apparatus 1 according to a fourth embodiment. The electrolytic apparatus 1 of the fourth embodiment comprises an electromagnetic valve 100 in a water supply pipe 80 a connected to a second inlet 12 a of an anode chamber 18 b. Water is intermittently delivered to only the anode chamber 18 b. In the fourth embodiment, a predetermined amount of water always flows into a cathode chamber 18 c. In this case, the difference in water pressure is generated between the cathode chamber 18 c and an intermediate chamber 18 a. However, between the anode chamber 18 b and the intermediate chamber 18 a, no difference in water pressure is generated. Thus, mixing of salinity in the anode chamber 18 b can be prevented. If a porous membrane 17 a which is resistant to gaseous chlorine is used as a first separating membrane, stable electrolysis can be performed. In consideration of use of aqueous sodium hydroxide, a cation-exchange membrane 13 b which has the difference in water pressure, is not water-permeable and does not allow mixing of salinity is employed for a second separating membrane which separates the cathode chamber 18 c from the intermediate chamber 18 a. In this case, since the type of the separating membrane used for the anode chamber 18 b is different from that of the cathode chamber 18 c, the pH of saline which is subjected to electrolysis is easily changed. Thus, saline is basically subjected to electrolysis in a static state. When the consumption of saline has reached the limitation, saline is replaced and wasted. (For example, a first delivery pump 50 is run every thirty minutes.) For this reason, a check valve 400 is provided in a supply pipe 20 a in order to prevent back-diffusion of saline which was changed in water quality from the intermediate chamber 18 a. The other structures of the electrolytic apparatus 1 of the fourth embodiment are the same as those of the electrolytic apparatus 1 of the first embodiment.
In the fourth embodiment, similarly to the first embodiment, the electrolytic apparatus 1 comprising the three-compartment electrolytic cell can prevent mixing of salinity in the anode chamber 18 b and the cathode chamber 18 c, prevent damage of the separating membranes by gaseous chlorine, etc., and perform stable electrolysis.
The present invention is not limited to the above-described embodiments, and may be realized by modifying structural elements without departing from the scope. Various inventions can be realized by appropriately combining the structural elements disclosed in the embodiments. For instance, some of the disclosed structural elements may be deleted. Some structural elements of different embodiments may be combined appropriately.
For example, the electrolyte fluid is not limited to saline, and may be appropriately selected depending on the purpose of use. Further, the electrolyzed water to be produced is not limited to aqueous hypochlorous acid or aqueous sodium hydroxide, and may be appropriately selected depending on the purpose of use.
The opening and closing time of the electromagnetic valve 100 and the time of electrolysis explained in the above embodiments may be appropriately changed depending on the purpose. For example, when the concentration of hypochlorous acid to be produced is changed to double, the potential applied to the anode 15 a may be doubled, or the closing time of the electromagnetic valve 100 may be approximately doubled without changing the applied potential. The opening time of the electromagnetic valve 100 may be shortened by increasing the setting value of the water delivery pressure of the delivery pump 50.

Claims

What is claimed is:

1. An electrolytic apparatus comprising:

an electrolytic cell comprising a first separating membrane which separates an anode chamber from an intermediate chamber through which an electrolyte fluid flows, a second separating membrane which separates the intermediate chamber from a cathode chamber, an anode provided in the anode chamber to face the first separating membrane, and a cathode provided in the cathode chamber to face the second separating membrane;

a water supply portion which supplies water to the anode chamber and the cathode chamber and intermittently changes a water supply and discharge amount to at least one of the anode chamber and the cathode chamber;

an electrolyte fluid supply portion which supplies and discharges an electrolyte fluid to the intermediate chamber; and

a controller which applies potential to the anode and the cathode to electrolyze the electrolyte fluid in a state where the water supply and discharge amount is small or in a water static state in at least one of the anode chamber and the cathode chamber.

2. The electrolytic apparatus of claim 1, wherein the water supply portion comprises a water supply pipe which leads water from a water supply source to the anode chamber and the cathode chamber; and an electromagnetic valve which is provided in the water supply pipe and opens and closes the water supply pipe, and

the controller intermittently opens and closes the electromagnetic valve for a predetermined time, and controls intermittent water supply and discharge to at least one of the anode chamber and the cathode chamber.

3. The electrolytic apparatus of claim 2, wherein at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied has a water pressure of 10 kPa or lower in the state where the water supply and discharge amount is small or in the water static state.

4. The electrolytic apparatus of claim 2, wherein at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied includes a water pressure lower than the intermediate chamber in the state where the water supply and discharge amount is small or in the water static state.

5. The electrolytic apparatus of claim 2, wherein at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied includes a water pressure higher than the intermediate chamber in a state where the water supply and discharge amount is large.

6. The electrolytic apparatus of claim 2, wherein at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied is separated from the intermediate chamber by a porous membrane having water permeability.

7. The electrolytic apparatus of claim 6, wherein the porous membrane has a water permeability of 0.1 to 100 ml/minute/cm²/MPa.

8. The electrolytic apparatus of claim 6, wherein the porous membrane has a pore diameter of 2 to 1000 nm.

9. The electrolytic apparatus of claim 2, wherein at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied has a capacity of 200 cc or greater.

10. The electrolytic apparatus of claim 2, wherein a water discharge pipe connected to at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied comprises an auxiliary chamber, and the anode chamber and the cathode chamber have a capacity of 200 cc or greater in combination with a capacity of the auxiliary chamber.

11. The electrolytic apparatus of claim 2, wherein the intermittent water supply amount is larger than a capacity of at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied.

12. The electrolytic apparatus of claim 2, which comprises a water discharge pipe connected to at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge, and a check valve provided in the water discharge pipe.

13. The electrolytic apparatus of claim 12, wherein the check valve is a safety valve which opens at a predetermined water pressure or a higher water pressure, and a predetermined water pressure is applied to at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied in the water static state.

14. The electrolytic apparatus of claim 13, wherein the predetermined water pressure is lower than or equal to 10 kPa.

15. The electrolytic apparatus of claim 1, wherein an amount of delivering the electrolyte fluid to the intermediate chamber is small or the electrolyte fluid is static in electrolysis.

16. The electrolytic apparatus of claim 1, wherein the electrolyte fluid supply portion comprises an electrolyte fluid tank which stores an electrolyte fluid; a supply pipe which leads the electrolyte fluid in the electrolyte fluid tank to the intermediate chamber; and a delivery pump provided in the supply pipe, and the controller intermittently supplies the electrolyte fluid to the intermediate chamber by the delivery pump.

17. The electrolytic apparatus of claim 16, wherein the electrolyte fluid supply portion comprises a discharge pipe which discharges the electrolyte fluid which had passed through the intermediate chamber from the intermediate chamber; and a check valve provided in the discharge pipe.

18. The electrolytic apparatus of claim 17, wherein the check valve is a safety valve which opens at a water pressure higher than a water pressure applied in the state where the water supply and discharge amount to at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied is small or in the water static state.

19. A method of producing an electrolyzed water by an electrolytic apparatus comprising an electrolytic cell comprising an intermediate chamber divided by a first separating membrane and a second separating membrane, anode and cathode chambers provided on both sides of the intermediate chamber, an anode provided in the anode chamber to face the first separating membrane, and a cathode provided in the cathode chamber to face the second separating membrane, the method comprising:

supplying an electrolyte fluid to the intermediate chamber;

supplying water to the anode chamber and the cathode chamber;

intermittently changing a water supply and discharge amount to at least one of the anode chamber and the cathode chamber; and

applying potential to the anode and the cathode to electrolyze the electrolyte fluid in the intermediate chamber and producing electrolyzed water in at least one of the anode chamber and the cathode chamber in a state where the water supply and discharge amount is small or in a water static state in at least one of the anode chamber and the cathode chamber.

20. The method of claim 19, wherein the water supply to at least one of the anode chamber and the cathode chamber is intermittently applied and stopped at predetermined time intervals, and the potential is applied to the anode and the cathode in a state where the water supply is stopped.

21. The method of claim 20, wherein the electrolyte fluid supply to the intermediate chamber is intermittently applied and stopped in synchronization with the water supply and stoppage.

22. The method of claim 19, wherein at least one of the anode chamber and the cathode chamber has a water pressure lower than the intermediate chamber in the state where the water supply and discharge amount is small or in the water static state.

23. The method of claim 19, wherein at least one of the anode chamber and the cathode chamber to which the intermittent water supply and discharge is applied has a water pressure higher than the intermediate chamber in a state where the water supply and discharge amount is large.