Patent Application
20160186337
Embodiments described herein relate generally to an electrolytic device and an electrode used for the electrolytic device.
As an electrolytic device, an electrolyzed-water production device for producing ionized alkaline water, ozone water, aqueous hypochlorous acid or the like is conventionally known. As the electrolyzed-water production device, a device comprising a three-chamber electrolytic tank (electrolytic cell) has been proposed. The three-chamber cell includes an electrolytic container divided into three chambers, that is, an anode chamber, an intermediate chamber and a cathode chamber by diaphragms. In such an electrolytic device, for example, salt water is introduced into the intermediate chamber, and water is introduced into the cathode chamber and the anode chamber on the right and left sides. Thus, the salt water in the intermediate chamber is electrolyzed by the anode and the cathode to produce aqueous hypochlorous acid from gaseous chlorine produced in the anode chamber and sodium hydroxide solution in the cathode chamber. Hypochlorous acid thus produced can be utilized as sterilizing solution and sodium hydroxide solution as a cleaning solution.
However, an electrolytic device having such a three-chamber cell involves reactions in a complicated way around the anode, which proceed from chlorine ions to gaseous chloride and then to hypochlorous acid. Here, if the reaction system does not take place appropriately, competitive gaseous oxygen is produced and thus the productivity of hypochlorous acid is reduced. Further, gaseous chloride and hypochlorous acid produced here are strong oxidizers, which may cause deterioration of diaphragms.
Various embodiments will be described below with reference to the accompanying drawings. In general, according to one embodiment, an electrolytic device comprises an electrolytic cell comprising a first electrode, a second electrode opposing the first electrode and at least one diaphragm provided between the first electrode and the second electrode. The first electrode is formed of a plate comprising a first surface opposing the diaphragm, a second surface located on an opposite side to the diaphragm, and first recess portions formed in the first surface with a first pattern. The first recess portions include a bottom surface apart from the first surface and through-holes each opening to the second surface of the first electrode and to a part of the bottom surface.
Throughout the embodiments, common structural members are designated by the same reference symbols, and the explanation therefor will not be repeated. Further, the drawings are schematic diagrams designed to assist the reader to understand the embodiments easily. Thus, there may be sections where the shape, dimensions, ratio, etc. are different from those of the actual devices, but they can be re-designed as needed with reference to the following explanations and publicly known techniques.
The electrolytic device 10 comprises an electrolyte supplier 19 which supplies an electrolyte, for example, saturated salt water, to the intermediate chamber 15a of the electrolytic cell 11, a water supplier 21 which supplies a solution to be electrolyzed, for example, water, to the anode chamber 15b and the cathode chamber 15c and a power supply 23 that applies positive and negative voltages respectively to the first and second electrodes 14 and 20.
The electrolyte supplier 19 comprises a salt water tank 25 to produce saturated salt water, a supply pipe 19a which conveys saturated salt water from the salt water tank 25 to a lower portion of the intermediate chamber 15a, a liquid feed pump 29 provided in the supply pipe 19a and a drainage pipe 19b which sends the electrolyte which has flowed through the inside of the intermediate chamber 15a from an upper portion of the intermediate chamber 15a to the salt water tank 25.
The water supplier 21 comprises a water supply source (not shown) which supplies water, a water supply pipe 21a which guides water to lower portions of the anode chamber 15b and the cathode chamber 15c from the water supply source, a first drainage pipe 21b to discharge the water which has flowed through the anode chamber 15b from an upper portion of the anode chamber 15b, a second drainage pipe 21c to discharge the water which has flowed through the cathode chamber 15c from an upper portion of the cathode chamber 15c and a gas-liquid separator 27 provided in the second drainage pipe 21c.
The operation of the electrolytic device 10 configured as described above, which actually electrolyzes salt water to produce an acidic solution (aqueous hypochlorous acid and hydrochloric acid) and alkaline water (sodium hydroxide) will now be described.
As shown in
Meanwhile, chlorine ions electrolytically dissociated in the salt water in the intermediate chamber 15a are attracted towards the first electrode 14, pass through the anion-exchange membrane 16 and flow into the anode chamber 15b. Then, the chlorine ions give electrons to the anode with the first electrode 14 to produce gaseous chlorine. After that, the gaseous chlorine reacts with water in the anode chamber 15b to produce hypochlorous acid and hydrochloric acid. The acidic solution thus produced (aqueous hypochlorous acid and hydrochloric acid) is discharged from the anode chamber 15b through the first liquid drainage pipe 21b.
Next, the structure of the electrolytic cell 11 will now be described in more detail.
The anion-exchange membrane 16 is disposed between the intermediate frame 22 and the anode cover 24, as a first diaphragm to separate the intermediate chamber 15a and the anode chamber 15b from each other, and the first electrode (anode plate) 14 is disposed near the anion-exchange membrane 16 in the anode chamber 15b. The cation exchange membrane 18 is disposed between the intermediate frame 22 and the cathode cover 26, as a second diaphragm to separate the intermediate chamber 15a and the cathode chamber 15c from each other, and the second electrode (cathode) 20 is disposed near the cation-exchange membrane 18 in the cathode chamber 15c.
A first inlet 34 communicating with the intermediate chamber 15a is formed in a lower end of the intermediate frame 22 and a first outlet 36 communicating with the intermediate chamber 15a is provided in an upper end thereof. The supply pipe 19a and the drainage pipe 19b are connected to the first inlet 34 and the first outlet 36, respectively.
As shown in
A second inlet 37 communicating with the lower end of the circulation grooves 32a is formed in a lower portion of the anode cover 24, and a second outlet 38 communicating with the upper end of the circulation grooves 32a is formed in an upper portion of the anode cover 24. The supply pipe 21a and the first drainage pipe 21b are connected to the second inlet 37 and the second outlet 38, respectively.
A plurality of ribs 35, circulation grooves 32b, and side grooves are each formed on an inner surface of the cathode cover 26 so as to extend in the perpendicular direction (the second direction Y). The circulation grooves 32b, the side grooves and the cation-exchange membrane 18 defines the cathode chamber 15c. Further, the circulation grooves 32b and the side grooves form a flow path for water to flow.
A third inlet 39 communicating with the lower end of the circulation grooves 32b is formed in a lower portion of the cathode cover 26, and a third outlet 41 communicating with the upper end of the circulation grooves 32a is formed in an upper portion thereof. The supply pipe 21a and the second drainage pipe 21c are connected to the third inlet 39 and the third outlet 41, respectively.
As shown in
A plurality of fixing bolts 50 are inserted through the peripheral portions of these structural components from, for example, the anode cover 24 side and the tip portions project from the cathode cover 26. A nut 52 is screwed into the tip portion of each fixing bolt 50. With the fixing bolts 50 and the nuts 52 as fastening components, the peripheral portions of the structural components are fastened respectively with each other to maintain the water tightness of the intermediate chamber 15a, the anode chamber 15b and the cathode chamber 15c.
As shown in
The anion-exchange membrane 16 is disposed to oppose one surface side of the intermediate frame 22, and the peripheral portion thereof is tightly attached to the intermediate frame 22 through the sealing material 40. Similarly, the cation-exchange membrane 18 is disposed to oppose the other surface side of the intermediate frame 22 and the peripheral portion thereof is tightly attached to the intermediate frame 22 through the sealing material 40. Note that the first diaphragm and the second diaphragm may be formed from not only an ion-exchange membrane but a porous membrane having water permeability.
The first electrode 14 and the second electrode 20 are each formed from a metal plate having a thickness of about 1 mm, formed into a rectangular shape having an outer size substantially equal to that of the intermediate frame 22. The first electrode 14 and the second electrode 20 each have a central portion (effective region) where micro-through-holes for passing liquid are formed, and a peripheral portion in which a plurality of through-holes through which fixing bolts 50 are inserted are formed. The first electrode 14 includes a contact terminal 14b projecting from a side edge thereof. Similarly, the second electrode 20 includes a contact terminal 20b projecting from a side edge thereof.
The first electrode 14 is arranged to oppose to and be tightly contact with the anion-exchange membrane 16. The second electrode 20 is arranged to oppose to and be tightly contact with the cation-exchange membrane 18.
Next, the structure of the first electrode (anode) 14 will be described in detail as a typical example of the electrodes.
As shown in
In the first surface 17a of the matrix 17, a first recess R1 having a first pattern is formed over the entire surface. In the second surface 17b of the matrix 17, a second recess R2 having a second pattern different from the first pattern is formed over the entire surface.
In this embodiment, the first recess R1 of the first pattern comprises a plurality of thin linear first recess portions 42 formed in the first surface 17a of the matrix 17 and the first recess portions 42 are each opened in the first surface 17a. Each of the first recess portions 42 includes a bottom surface (bottom portion) 42a which is apart from the first surface 17a, that is, recessed from the first surface 17a by a predetermined depth. The second recess R2 of the second pattern comprises a plurality of thick or coarse linear second recess portions 44 formed in the second surface 17b of the matrix 17 and the second recess portions 44 are each opened to the second surface 17b. The first recess portions 42 and the second recess portions 44 are formed in the entire rectangular effective region excluding the peripheral portion of the matrix 17. A plurality of first recess portions 42 communicate with one second recess 44 and each of the communicating portions forms a through-hole 46. Each of the through-holes 46 opens to a part of the bottom surface 42a of the first recess portion 42 and opens to the second surface 17b of the matrix 17. The entire surface of the first electrode 14 is covered with an iridium oxide catalyst. The iridium oxide catalyst produces a lower overvoltage in the gaseous chlorine production than in the competitive gaseous oxygen production, and if there are a certain number of chlorine ions around the anode, gaseous chlorine is selectively produced.
As shown in
In this embodiment, the second recess portions 44 on the second surface 17b side are formed in a straight line extending in a direction crossing the first direction X, that is, for example, a second direction Y orthogonal to the direction X. The second recess portions 44 are arranged to be parallel to each other. The second recess portions 44 each extend from one end to the other end of the effective region (central region of the rectangular shape, excluding the peripheral portion on the second surface) of the second surface 17b. An opening width W3 of the second recess portions 44 is sufficiently larger than the opening width W1 of the first recess portions 42, for example, 2.4 mm, a pitch P2 of the second recess portions 44 in the arranging direction X is 3 mm, and a depth D2 of the second recess portions 44 is greater than a half of the thickness T of the matrix 17, more specifically, 0.6 to 0.7 mm. In this embodiment, the second recess portions 44 are each formed so as to widen from the bottom side toward the second surface 17b, more specifically, to have substantially a trapezoidal shape in cross section. The both side surfaces which define each second recess 4442 extend while inclining with respect to the second surface 17b. With this structure, the second recess portions 44 communicate with a plurality of first recess portions 42 by a through-width W4 of 1.2 mm.
The first electrode 14 configured as above can be produced by the following procedure, for example. That is, the first surface 17a and the second surface 17b of the matrix 17 are etched to be partially cut out, thus forming the first recess R1 of the first pattern and the second recess R2 of the second pattern. The cross-sections of the first recess portions 42 and the second recess portions 44 may be various shapes, more specifically, not only a trapezoidal but also rectangular, semicircular, elliptical, arc-like and the like. Further, the angle made by the first recess portions 42 and the second recess portions 44 crossing therewith is not limited to right-angles, but may be any other angles.
With the structure, the first recess portions 42 and the second recess portions 44 of the first electrode 14 communicate respectively with each other at intersections to form a great number of through-holes 46. The first surface 17a opposing the first diaphragm 16 includes the most, more specifically, 80% of the surface opened by the first recess portions 42, and the area opened and made to communicate is set as low as 16% of the surface area of the electrode. Further, in consideration of the collection of bubbles from the through-holes 46, the water flow is set in the width direction (the second direction Y) of the through-holes 46. As described, in this electrode, the matrix 17 is etched from both sides, namely, the first and second surfaces 17a and 17b, and therefore it is possible to change the open aperture ratio in each surface. Thus, this electrode can exhibit a function which cannot be attained with the conventional electrode having the same open aperture ratio in both surfaces, manufactured by, for example, a die cut process. It is preferable here that the open area ratio of the through-holes 46 formed by the first recess portions 42 and the second recess portions 44 communicating with each other with respect to the entire area of the first surface 17a be no more than a half of the open area ratio of the first recess portions 42 to the entire area of the first surface.
Note that in this embodiment, the second electrode (cathode) 20 is similar in structure to the first electrode 14.
As shown in
Further, as shown in
According to the electrolytic device 10 of the first embodiment, which employs the first electrode 14 having the above-described structure, an outstanding advantageous effect can be obtained as compared to the case of employing a conventional electrode formed by stamping (punching process) or expanding after making nicks (expand/lath processing). In other words, a great number of first recess portions 42 are formed in the first surface 17a which opposes the first diaphragm 16 of the first electrode 14 and therefore the first electrode 14 and the first diaphragm 16 can be set apart from each other by a slight distance without providing a separate member such as a spacer. With this structure, it is possible to improve the high production efficiency and the anti-degradation of the diaphragm both at the same time.
With the conventional stamping process, an electrode is basically formed to include only through-holes made from the first to second surfaces 17a and 17b with the same open area. Therefore, if the first electrode 14 and the first diaphragm 16 are attached tightly to each other, the main reaction occurs on the first surface 17a which opposes the first diaphragm 16. Here, the first surface is tightly attached to the first diaphragm, a problem may arise, in which the diaphragm 16 is degraded by reaction products. Further, when the first surface and the first diaphragm are tightly attached, another problem may arise, in which products produced by the electrolytic reaction cannot be collected, thus degrading the efficiency.
In this embodiment, the first recess portions 42 (first recess R1) are formed in the first surface 17a, which is the main reaction field, at an area ratio of high as 80%. With this structure, reaction products are quickly collected through a slight gap D1 (first recess portion 42) and through-holes 46 into the circulation grooves 32a, thereby making it possible to suppress degradation of the first diaphragm 16.
It is ideal that the first recess portions 42 have an open area occupying ratio as high as possible, but in practice, the above-described effect can be sufficiently exhibited if they occupy 60% or more of the effective region of the first surface 17a. Further, it is more effective if the pitch P1 of arrangement of the first recess portions 42 is finer to collect the products from the portions thereof which are in contact with the first diaphragm 16. In practice, the effect can be sufficiently exhibited if the pitch P1 is 0.8 mm or less. It is ideal that the depth D1 of the first recess portions 42 is less as possible, but in practice, the above-described effect can be sufficiently exhibited if it is 0.5 mm or less. Further, if the minimum width of the region in the first surface 17a of the first electrode 14 is formed, is set to 0.3 mm or less, that is, the value obtained by subtracting the opening width W1 of the first recess portions 42 from the arrangement pitch P1 of the first recesses 42 is 0.3 mm or less, it becomes easy to collect the substances produced by the electrolytic reaction from the first surface 17a tightly attached to the diaphragm. Thus, the above-described effect can be exhibited.
One of the functions of the second recess portions 44 of the first electrode 14 is to form the through-holes 46 for collecting the products from the first recess portions 42 formed shallow at high precision to the anode chamber 15b side. Another function of the second recess portions 44 is to collect the current electrolyzed by the first recess portions 42 at lower resistance. To achieve this, the second recess portions 44 are formed to be coarse linear dent portions which cross the first recess portions 42. By crossing the first recess portions 42 and the second recess portions 44 perpendicularly with each other, the intersections of the first recess portions 42 and the respective second recess portions 44 communicate with each other to extract hypochlorous acid or the like, produced in the first recess portions 42 from the through-holes 46 to the anode chamber 15b side. Note that the area ratio of the through-holes 46 with respect to the area of the first electrode 14 is set as low as 16%. This is because the region of the first recess portions 42, lost by the through-holes 46 should be made as small as possible. As the area of the through-holes 46 becomes larger, the number of chlorine ions lost by diffusion through the through-holes 46 increases. For this reason, the area of the through-holes 46 should desirably be set within 30% of the area of the electrode.
Further, in this embodiment, the first recess portions 42 and the second recess portions 44 are formed into a linear shape, whose longitudinal directions cross each other orthogonally. With this structure, one first recess portion 42 communicate with a plurality of second recess portions 44 to form a through-hole 46, thereby improving the drainage of the first recess portions 42 better than the case where the first recess portions 42 and the second recess portions 44 communicate with each other one to one. That is, a plurality of through-holes 46 are provided in one second recess 44 without making a dead end, thus forming such a structure for reaction products, especially, air bubbles to easily pass through. The linear second recess portions 44 are arranged to intersect perpendicularly with the first recess portions 42 at a coarse pitch so as to set the ratio of the area of the through-holes to as low as 16% while keeping the ratio of the open area of the first recesses 42 as high as 80%. Thus, the lowering of the concentration, which is caused by the diffusion of the electrolyte from the through-holes 46, can be prevented without the first diaphragm 16 being degraded by the reaction products.
The second recess portions 44 are arranged at a coarse pitch P2 of several millimeters, for example, 3 mm, so that the volume of the matrix 17 remains at large and the current produced by electrolysis can be supplied at lower resistance. Further, the intensity of the electrode itself can be maintained. In practice, the pitch P2 is set to 1 mm or more to obtain a sufficient feed resistance.
As described above, according to the first embodiment, it is possible to provide a long-life and efficient electrolytic device and an electrode, in which degradation of the diaphragm can be suppressed.
Next, the electrodes of electrolytic devices according to various modifications will be described.
Note that in the modifications described below, the elements which are identical to those of the first embodiment are denoted by the same reference symbols, and parts different from those of the first embodiment will be mainly described in detail.
(First Modification)
As shown in
With the above-described structure, the area ratio of the through-holes 46 is decreased to low as about 5%, thereby making it possible to further suppress the chlorine ions having passed through the first diaphragm 16 to diffuse in the circulation grooves 32a. Thus, the chlorine ion concentration in the first surface 17a of the first electrode 14 is increased to suppress the production of gaseous oxygen, thereby improving the production efficiency of acidic solution.
(Second Modification)
As shown in
According to the second modification having the above-described structure, the second recess portions 44 of each row is divided into a plurality of segments so that wide linear portions remain between adjacent pairs of the segments of each second recess. With this structure, the mechanical strength is improved in all plane directions of the first electrode 14, and also the anisotropy of the feed resistance of the first electrode can be relaxed.
Note that in the first embodiment described above, the second recess portions 44 are formed concurrently with the circulation grooves 32a, but the first electrode 14 may be placed in the direction in which the second recess portions 44 intersect perpendicularly with the circulation grooves 32a.
(Third Modification)
According to the third modification, the first electrode 14 comprises a large number of first recess portions 42 formed in the first surface 17a, which constitute the first recess R1. The second recesses formed in the second surface 17b of the first electrode 14 are formed from the through-holes 47. That is, the through-holes 47 are opened in the first surface 17a and the second surface 17b of the matrix 17. The through-holes 47 each have, for example, a circular shape whose diameter is larger than the width W1 of the first recess portions 42. In other words, the opening length of the through-holes 47 in the second direction Y is grater than the width W1 of the first recess portions 42. A plurality of first recess portions 42 communicate with one through-hole 47.
Since high precision is required, the first recess portions 42 of the first electrode 14 are formed by etching or photolithography, but the through-holes 47 as the second recesses are not so highly precise and may be formed by the conventional punch process.
(Fourth Modification)
According to the fourth modification having the above-described structure, the first recess portions 42 of each row is divided into a plurality of segments so that linear portions remain between adjacent pairs of the segments of each first recess. With this structure, the mechanical strength is improved in all plane directions of the first electrode 14, and also the anisotropy of the feed resistance of the first electrode can be relaxed.
(Fifth Modification)
(Sixth Modification)
(Seventh Modification)
As shown in
According to the seventh modification having the above-described structure, the area on the first surface 17a which is brought into in contact with the diaphragm can be further reduced by providing the third recess portions. Further, the main reaction region of the electrode is the lower surfaces of the first recesses R1 and the area of the reaction region can be expanded by the third recess portions.
(Eighth Modification)
As shown in
In the eighth modification having the above-described structure, the third recess portions are provided intermittently, i.e., the length or width of each third recess portion is reduced, and thus the amount of deformation of the diaphragm which may warp along the first recesses R1 can be reduced. Therefore, it is possible to set the positions of the diaphragm and the electrode more precisely.
Moreover, according to the eighth modification, as shown in
Note that the eighth modification is described for the case where the third recess portions are arranged in line along the second direction Y, but the arrangement is not limited to this. The third recess portions may as well be arranged to be shifted from each other in the first direction, or, for example, in a staggered manner.
The present invention is not limited to the embodiments and modifications described above but the constituent elements of the invention can be modified in various manners without departing from the spirit and scope of the invention. Various aspects of the invention can also be extracted from any appropriate combination of a plurality of constituent elements disclosed in the embodiments and modifications. Some constituent elements may be deleted in all of the constituent elements disclosed in the embodiments. The constituent elements described in different embodiments may be combined arbitrarily.
For example, the first electrode and the second electrode are not limited to rectangular shapes, but various other forms may be selected. Further, the material of each structural component is not limited to that employed in the embodiments or modifications discussed, but various other materials may be selected as needed. The electrode structure discussed above may be applied not only to the first electrode but also to the second electrode (cathode). The electrolytic cell of the electrode device is not limited to a three-chamber type, but it may as well be applied to a two-chamber- or single-chamber type or any electrolytic cells with electrodes in general. The electrolytes and product are not limited to salt or hypochlorous acid, but may be developed into various electrolytes and products.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-191565 | Sep 2014 | JP | national |
This application is a Continuation application of PCT Application No. PCT/JP2015/075626, filed Sep. 9, 2015 and based upon and claiming the benefit of priority from Japanese Patent Application No. 2014-191565, filed Sep. 19, 2014, the entire contents of all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2015/075626 | Sep 2015 | US |
| Child | 15062619 | US |
