US3759814A - Electrolytic apparatus for producing hydrated iron oxide - Google Patents

Abstract

ELECTRIC CURRENT IS FLOWN THROUGH THE ELECTROLYTIC CELL WHILE RAW WATER IS BEING FED THERETO.

AN ELECTROLYTIC ELECTRODE DEVICE, WHICH COMPRISES AN INSOLUBLE ANODE PLATE FORMED WITH A PLURALITY OF LIQUID HOLES AND POSITIONED IN THE LOWER PART OF AN ELECTROLYTIC CELL, BAR IRON PROVIDED SUBSTANTIALLY VERTICALLY ON SAID ANODE, CATHODE MEMBERS LOCATED PARALLELLY AND ABOVE THE TOP OF SAID BAR IRON, AND MEANS TO INSULATE ELECTRICALLY SAID BAR IRON AND CATHODE FROM EACH OTHER, WHEREBY AN

Description

Sept. 18, 1973 AK|TQ NAKAGAWA ET AL 3,759,814

ELECTROLYTIC APPARATUS FOR PRODUCING HYDRATED IRON OXIDE Filed Aug. 4, 1971 3 Sheets-Sheet 2 INVEN'I'ORS M: 1M magnum BY 0 P 29" mmanvn Kl'ncHiRO vsmsuao (75m Mn Attorney:

ELECTROLYTIC APPARATUS FOR PRODUCING HYDRATED IRON OXIDE 3 Sheets-Sheet {5 Filed Aug. 4, 1971 FIG. 7

23C 5 b 23a United States Patent ELECTROLYTIC APPARATUS FOR PRODUCING HYDRATED IRUN OXIDE Akito Nakagawa, Kenji Ueda, Hironari Tanigawa, and

Keiichiro Ishiguro, Nagasaki, Japan, assignors to Mitsubishi Jukogyo Kabushiki Kaisha, Tokyo, Japan Filed Aug. 4, 1971, Ser. No. 168,858 Claims priority, application Japan, Aug. 14, 1970,

Int. Cl. B01k 3/04 U.S. Cl. 204--275 4 Claims ABSTRACT OF THE DISCLOSURE An electrolytic electrode device, which comprises an insoluble anode plate formed with a plurality of liquid holes and positioned in the lower part of an electrolytic cell, bar iron provided substantially vertically on said anode, cathode members located parallelly and above the top of said bar iron, and means to insulate electrically said bar iron and cathode from each other, whereby an electric current is flown through the electrolytic cell while raw water is being fed thereto.

This invention relates to an electrolytic electrode device for condensers which are used on thermal plants, chemical plants, ships and the like.

Heretofore, much of the cooling pipes for such plants and the like have been made of corrosion-resistant copper or copper alloy. They have disadvantages, however, in that, depending on the service conditions and environments, they may be corroded, thereby shortening the life of the cooling line as a whole. Especially when the condenser uses a large volume of sea or river water as the medium for its cooling pipes, the corrosion of the cooling line can bring the operation of the entire system to a stopsThe causes of the corrosion are many and diversified; they include, for example, the potential difference between oxygen and different metals, or battery action which leads to local electrolysis and corrosion, dezincification, impact of running water which results in impact corrosion, impurities which effect a deposit attack, and stresses which also corrode the metals.

In order to avoid the corrosion of the types above described, means to introduce ferrous sulfate into cooling water thereby to form an anti-corrosive lining on the inner wall surface of the cooling pipes, and means to supply iron ions to cooling water through electrolysis of iron by an electrolyzer as shown in FIG. 1 were recently proposed and have met wide acceptance.

The former, or the means of forming a protective lining of ferrous sulfate introduced into the cooling water, is disadvantageous because ferrous sulfate comprises anhydrous salt and many diiferent hydrous salts aside from a heptahydrate, all with different iron contents, and, unless it is strictly controlled, the chemical to be added cannot be maintained in a proper proportion to the water volume. If the chemical proportion is too large, the chemical will deposit to excess on the inner wall of the cooling pipe, thus forming an excessively thick anti-corrosive lining for adequate heat conduction, or the chemical thrown into the cooling water may directly cause a corrosion.

The latter, orthe means of supplying iron ions to cooling water through the electrolysis of iron by an electrolyzer as shown in FIG. 1, also has shortcomings as will be described below. Referring to FIG. 1, numeral 1 indicates a tubular electrolytic cell body, for example, in the form of a cylinder with a substantially vertical axis. The cell body .1 is provided with fittingflauges 2a, 2b around the upper and lower' end openingsiIt is made of a syn- Patented Sept. 18, 1973 thetic resin or iron plates, formed with a rubber lining in the case of iron plates for the dual purpose of corrosion resistance and insulation. The lower flange 2b of the cell body 1 is superposed with an insoluble anode plate 4 formed with a plurality of liquid holes 3a and a loadsupporting plate 5 also formed with a plurality of liquid holes 3b of the same shape as said liquid holes 3a and in the positions matching the same, and a funnel-shaped end cover 6 is attached to the superposed plates.

Usually the insoluble anode plate 4 is made of platinum, lead-silver alloy, magnetic oxide of iron, platinumplated titanium or the like, and the load-supporting plate 5 is made of a synthetic resin or the like. The funnelshaped cover 6 is provided with an inlet pipe 7 for cooling water as shown at the upper left part thereof, and is also provided with a normally closed drain pipe 8 at the bottom. Over the insoluble anode plate 4 is placed a carbon plate 9 for protecting the anode plate. The carbon plate 9 is formed with liquid holes 3c at points corresponding to the holes 3a. Above the carbon plate 9, or inside the electrolytic cell body 1, there are contained a plurality of scrap iron pieces 10 of diameters larger than those of the liquid holes 3a, 3b, 30. To the upper flange 2a of the cell body 1 is attached a cathode plate 11, for example in the form of an iron grid, which is perforated with a plurality of liquid holes, and an inverted-funnelshaped cover 13 formed with an electrolyte outlet pipe 12 at the top is secured to the upper flange 2a through the cathode 11. The anode plate 4 and the cathode plate 11 are connected, respectively, to the positive and negative poles of an electric source (not shown).

In operating the electrolyzing apparatus of the construction above described, a DC voltage is applied between the anode 4 and the cathode 11 while introducing raw water for cooling, for example sea Water, into the cell through the inlet pipe 7. The current passes through the insoluble anode 4, carbon plate 9, and scrap iron pieces 10 and reaches the cathode 11. During this period the scrap iron pieces 10 are melted in the manner as represented by the Formula A below in proportion to the current applied. As a result, the electrolyte containing Fe++ flows out of the outlet pipe 12, and the inner surface of a copper or copper alloy cooling pipe (not shown) in communication with the outlet pipe 12 is anti-corrosively lined with the hydrated iron oxide (FeOOI-I) as represented by the Formulas B and C below. Thus, as the scrap iron pieces 10 melt,

Fe Fe+++2e (A) and, as the Fe++-containing electrolyte flows out through the cooling pipe,

with the result that the inner surface of the cooling pipe is coated with an anti-corrosive film of hydrated iron oxide (FeOOH).

However, with the apparatus above described, the operation for an extended period of time tends to cause dropping of the scale, as of magnesium hydroxide, Mg(OH)2, and calcium carbonate, CaCO from the cathode 11 and accumulation of the scale on the scrap iron pieces 10, even allowing part of the deposited scale to gain entrance into the spaces among the scrap iron pieces 10 and thereby choke the flow passages. The rate of cooling water which flows into the cooling pipe decreases to disadvantage. Moreover, the electrolysis with the current applied as above causes melting of the upper surface of the scrap iron pieces 10 nearest to the cathode 11, and therefore the liquid resistance between the scrap iron pieces 10 and the cathode increases and the current is thereby reduced. This, combined with the resistance by the scale accumulated on the scrap iron pieces 10, makes it necessary to increase the current in order to obtain a desired Fe++ amount. Accordingly, the cell voltage of the electrolytic cell 1 must be increased as represented by the curve D of FIG. 2, with a consequent increase of the power consumption. This necessitates control through frequent opening of the electrolytic cell 1 to maintain the desired conditions. Further, in case when the electrolytic apparatus shown in FIG. 1 is installed, for example, on a ship, Where it is subjected to vibration due to the rolling and pitching of the vessel, the insoluble anode 4 tends to be damaged thereby.

The present invention has been prefected with the foregoing in view. It comprises, in essence, an insoluble anode plate formed with a plurality of liquid holes and positioned in the lower part of an electrolytic cell, bar iron provided substantially vertically on said anode, cathode members located parallelly and above the top of said bar iron, and means to insulate electrically said bar iron, and means to insulate electrically said bar iron and cathode members from each other, whereby an electric current is flown through the electrolytic cell while sea water is being fed thereto. According to this invention, an electrolytic electrode device is provided whose power consumption is considerably saved through the reduction of the electrolytic cell voltage and in which the clogging of the flow passages with any scale from the cathode is prevented and the electrolytic cell is capable of use in a closed state for an extended period of time, even in a place subject to vigorous rocking or vibration.

These and other objects, advantages and features of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a vertical sectional view of a conventional electrolytic electrode device;

FIG. 2 ls a characteristic curve showing changes of the electrolytic cell voltage with time for electrolysis in da s;

FIG. 3 is a vertical sectional view of an embodiment of the invention;

FIG. 4 is a transverse sectional view of the embodiment of FIG. 3;

FIG. 5 is a perspective view of the detail of the anode assembly of another embodiment;

FIG. 6 is a transverse sectional view of the second embodiment;

FIG. 7 is a vertical sectional view of the anode assembly of still another embodiment.

The first embodiment of the invention will now be described with reference to FIGS. 3 and 4. As shown in FIG. 3, numeral 21 indicates a tubular electrolytic cell body in the form, for example, of a cylinder with a substantially vertical axis. The cell body 21 is provided with fitting flanges 22a, 22b around the upper and lower end openings. It is made of a synthetic resin or iron plates, formed with a rubber lining in the case of iron plates for the dual purpose of corrosion resistance and insulation. The lower flange 22b of the cell body 21 is superposed with an insoluble anode plate 24, for example of platinum, formed with a plurality of liquid holes 23a and a load-supporting plate 25 also formed with a plurality of liquid holes 23b of the same shape as said liquid holes 3a and in the positions matching the same, and a funnel-shaped end cover 26 is attached to the superposed plates. The funnel-shaped end cover 26 is provided with a normally closed drain pipe 27, and on one side of the cell body 21 is provided an inlet pipe 28 for sea water for cooling use, for example at right angles to the axis of the tank body. Over the in soluble anode plate 24 is placed a carbon plate 29 for protecting the anode plate 24. The carbon plate 29 is formed with liquid holes 23c at points corresponding to the holes 230. Above the carbon plate 29, there are placed a plurality of bar iron 30 accommodated in the cell body 21. The bar iron 30 is larger in diameter than the liquid holes 23a, 23b, and 230.

To the upper flange 22a of the cell body 21 is attached a cathode plate 31, for example in the form of an iron grid, which is formed with a plurality of liquid holes, and an inverted-funnel-shaped cover 33 formed with an electrolyte outlet pipe 32 at the top is secured to the upper flange. To the cathode 31 are attached a plurality of cathode bars 31a directed vertically downward around the bar iron 30. The lower ends of the cathode bars 3101 are kept short of contact with the carbon plate 21, and are insulated with a synthetic resin or the like to avoid consumption of the carbon plate 29 due to any localized high current. Between the cathode bars 31a and the bar iron 30 is disposed an insulating cylinder 35 which is open at the top and the bottom and is formed with a plurality of liquid holes '34 throughout the shell. This insulating cylinder 35 is made, for example, of a synthetic resin and protects the bar iron 30 from falling into contact with the cathode bars 31a thereby forming a short-circuit. The anode plate 24 and the cathode plate 31 are connected, respectively, to the positive and negative poles of an electric source (not shown). I

With the construction above described, the apparatus operates in the following manner. When a DC voltage is applied between the anode 24 and the cathode 31 while introducing sea water for cooling into the cell through the inlet pipe 28, the current passes through the insoluble anode 24, carbon plate 29, bar iron 30, and liquid holes 34 of the insulating cylinder 35, and reaches the cathode bars 31a. At the same time, a part of the current flows through the top opening of the insulating cylinder 35 to the cathode 31. In the meantime, the bar iron 30 is melted in proportion to the current supplied, in the manner well known to the art and according to the Formula A above. The electrolyte that contains iron ions as represented by the formula Fe Fe++}+2e flows out through the outlet pipe 32 and the drain pipe 27, so that the inner wall surfaces of copper or copper alloy cooling pipes (not shown) connected, respectively, to the pipes 27, 32 are anti-corrosively coated with hydrated iron oxide (FeOOH) in accordance with the Formulas B and C. Because the cathode 31 has liquid holes above the bar iron 30 and the bar iron 30 in turn is opposed to a plurality of bar cathodes around its circumference, there is no possibility of a part of the iron in the upper part of the cell 21 being rapidly melted away as in a conventional cell. As a whole the bar iron 30 melts uniformly with no such sharp increase in the liquid resistance between the cathode 31 and the anode 24 as is the case with ordinary arrangements. Further, if the scale of magnesium hydroxide, Mg(OH)- and the like comes off from the cathode, it has no eifect whatsoever upon the liquid resistance between the bar iron 30 and the bar cathodes 31a, and the resistance remains unchanged. The use of bar iron 30 precludes the clogging of the flow passage with the scale removed from the cathode. Therefore, it is not necessary to open the electrolytic cell 21 after many hours of operation to eliminate the scale droppings as required with a conventional cell. For this reason and by the abovementioned reason of no increase in the liquid resistance, the cell voltage of the electrolytic cell-21 draws a lower curve B as shown in FIG. 2 than the comparative curve D of a conventional apparatus, thus indicating a considerable saving of power consumption. The provision of the insulating cylinder 35 between the cathode bars 31a and the bar iron 30 avoids short-circuiting in between in case the bar iron should fall against the bar electrodes, and makes it possible to install the apparatus in a place subject to vigorous vibration, as on a ship. These are extremely practical advantages. Moreover, because the free ends of the cathode bars 31a are electrically insulated, no localized high current flows between the cathode bars and the carbon plate 29, and therefore the carbon plate 29 is protected against wear due to oxidation.

While the embodiment above described uses platinum as the insoluble anode 24, it should be apparent of course to those skilled in the art that platinum may be replaced by a lead-silver alloy, magnetic oxide of iron, platinumplated titanium or the like. Also, the inlet pipe 29 for the sea Water for cooling use which is provided in the direction at right angles to the axis of the electrolytic cell 21 may be provided in some other way, for example in the direction tangential to the cell 21, in which case an additional advantage of effective removal of scale from the cathodes 31, 31a will be attained because the sea water introduced into the cell 21 will flow therein in the form of a swirling flow.

In FIGS. and 6 there is shown another embodiment of the present invention. It differs from the first embodiment in the following points. Throughout the figures illustrating the two embodiments, like numerals indicate like parts and the description of those parts will be omitted hereunder. In the second embodiment, a plurality of bar iron groups 43 each consisting of a plurality of bar iron elements 41 bound together with an insulating frame 42 are held substantially vertically or upright on an insoluble anode 24 through a carbon plate 29, between adjacent liquid holes 23a of the anode 24, by means of clamps 421; provided at the bottom of the insulating frames 42. In brief, the second embodiment is characterized in that the bar iron groups 43 are secured upright by means of clamps 42b so that they are held between the edges of the adjacent liquid holes 23a (23b, 23c) and 23a (23b, 23c), and that the cathode bars 31a are provided along the liquid holes 23a, 23b, and 230 as shown in FIG. 6. Thus, by dint of the insulating frames 42 which secure them in position, the bar iron groups 43 will have less chance of falling by rocking or vibration and provide greater safety than the arrangement of the first embodiment. Moreover, because the cathode bars 31a are provided along the liquid holes 23a, 23b, and 23c, the scale which once deposited on the cathode bars 31a and has come off therefrom can be easily discharged from the cell via the liquid holes 23a, 23b, and 23c.

FIG. 7 illustrates a third embodiment of the invention. Description of the parts bearing the same reference numerals as those of the two other embodiments will be omitted hereunder. This third embodiment differs from the others in the following points. It uses as the bar ion 30 a plurality of iron tubes, each of which receives an insulating cylinder 51 which in turn accommodates a cathode bar 53. The insulating cylinder 51 is formed with a plurality of liquid holes 52 and has a lower extension 51b for fixing use which is fitted securely in the superposed liquid holes 23c, 23a, and 23b, respectively, of a carbon plate 29, an insoluble anode plate 24, and a loadsupporting plate 25. The cylinder is open at the top and bottom ends.

As described hereinabove, the present invention provides an arrangement comprising, in essence, an insoluble anode plate formed with a plurality of liquid holes and positioned in the lower part of an electrolytic cell, bar iron provided substantially vertically on said anode, cathode members located parallelly and above the top of said bar iron, and means to insulate electrically said bar iron and cathode members from each other, so that an electric current is flown through the electrolytic cell while sea Water is being fed thereto. With this construction, there is no possibility of the flow passage being clogged by the scale which has come olf from the cathode after prolonged operation of the apparatus, and the electrolytic cell can be used in an enclosed state for a long period of time. Moreover, the bar iron is enabled to melt uniformly throughout by the action of the cathode members provided along its length and thereabove, and therefore any sharp increase of the liquid resistance between the cathode and bar iron is prevented. Further, because the insulation is interposed between the cathode and bar iron thereby precluding short-circuiting, the electrolytic electrode device according to the: invention is extremely safe against rocking and vibration.

What is claimed is:

1. An electrolytic electrode device comprisin an electrolytic cell body, an insoluble anode plate having a plurality of liquid openings disposed in a lower portion of said cell body, a carbon plate superimposed on said anode plate for protecting the latter, bar iron substantially vertically disposed on said superimposed carbon plate and anode plate, cathode means in said cell body having parts thereof disposed parallel to said bar iron and parts thereof disposed above said bar iron, and means to electrically insulate said bar iron and cathode means from each other, whereby an electric current is passed through the device as sea water flows therethrough.

2. An electrolytic electrode device according to claim 1 wherein said carbon plate has a plurality of openings aligned with said plurality of openings in said anode plate, said bar iron comprising a plurality of bar iron groups each including a plurality of bar iron elements, said bar iron groups being disposed generally upright on said superimposed carbon plate and anode plate between said aligned openings.

3. An electrolytic cell according to claim 1 wherein said bar iron is in the form of a plurality of iron tubes, said insulating means including at least one insulating cylinder disposed about said iron tubes, at least some of said parts of said cathode means being accommodated in said cylinder, said cylinder being formed with a plurality of liquid openings in its circumferential wall.

4. An electrolytic cell according to claim 1 wherein said carbon plate and anode plate are disposed on a support plate.

References Cited UNITED STATES PATENTS 1,335,210 3/1920 Von Wurstemberger 204196 3,448,035 6/1969 Serfass 204-272 2,801,697 8/1957 Rohrback 204-275 FOREIGN PATENTS 1,104,078 2/ 1968 Great Britain 204-272 JOHN H. MACK, Primary Examiner W. T. SOLOMON, Assistant Examiner US. Cl. X.R.

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