US734312A - Apparatus for the electrolytic decomposition of alkali chlorids. - Google Patents

Description

No. 734,312. PATBNTED JULY 21, 1903.

G. FOURNIER..

APPARATUS FOR TH BLBCTROLYTIG DHGOMPOSITION 0I ALKALI GHLORIDS.

APPLICATION FILED JUNE 25, 1902.

N0 MODEL. Z SHEETS-SHEET 1.

lin- .I Ihm u 95 IA Z y///////// l' gld- I 'THE Nonms PETERS co., Fnoroumo., WASHINGTON. n. n

PATLNTLD JULY 21, 1903.'

" QNL 734,312.

` I G. FOURNIER. APPARATUS FOR THE ELEGTROLYTIC DECOMPOSITIQN OF ALKALI GHLORIDS.

APPLIUATION FILED JUNE 25'l Ieoz.

2 SHEETS-SHEET 2.

L B D 0 M 0 N ergy consumed; but in the best arrangef theoreticalconsiderations must necessarily ferred to as A and B) separated by aporous bility of a in B. By exerting a pressure on.

NiTED SIT-MVES Patented Juiy 21,1905.

PATENT OEErcE.

APPARATUS FOR THE EtEcTRoLYTlC' DEcoMroSmoNfoF ALKALI cHLomDs.

SPECIFICATION forming part of Letters PatentrNo. 734,312, dated J lily 21, 1903-.

Application filed June 25) 1902.

.To @ZZ whom t may concern,.-

Be it known that I, CHARLES FOURNIER, chemist, a citizen of the Republic of France, residing at Geneva, in the Republic of Switzerland, have invented cert-ain new anduse; ful Improvements in Apparatus for the Electrolytic Decomposition of Alkaline Chlorids, of which the following is a specification.

The electrolytic production of chlorin and caustic soda from common salt takes place almost universally by thc use of suitable porous partitions which divide the electrolytes into chambers-that is to say, the cathodechamber, in which the caustic soda accumulates, and the anode-chamber, in which the chlorin accumulates. No matter Whatfowrm is given to the diaphragm and of what material it is made it has, however, hitherto been impossible to obtain a quantity of chlorin and A caustic soda equivalent to the electrical enmeuts a yield not exceedingeighty per cent. is attained. The loss of energy thus resulting is to be ascribed to the mutual action of chlorin and soda solution; and the present@ invention has for its object to avoid'this action. For a better explanation the following be considered. Let us assume two-uids (which to facilitate description will be re partition and that uid A contains a substance which will be referred to as ct, which is soluble in iiuid B. According to the law of diffusion-pressure a portion of the s ubstance a must travel from A to B and there oe dissolved, and the amount thus traveling is the more considerable the greater the solu- B whichis greater than that bearing on A the transmission of a to B may indeed be considerably diminished; but by the use of this means, again, a larger portion of Bis forced through the pores of the diaphragm-that is to say, mingles with A.' If in addition lthe liquid B is in a position to chemically combine witho, forming a soluble compound b, the hereinbefore-mentioned action-of the diffusion pressure is still further increased. This is the case to a still greater extent if B in turn can act chemically on b, forming a soluble compound b', which in turn may further react, if desired, with a. The appearsertn No. 113.169. maanden ances arising in the electrolysis ofchlorid-ofsodium solutions by the use of diaphragme correspond exactly to the circumstances hereinbefore depicted and cause a defective yield. Thevcathode iiuid A contains caustic soda ct in solution. The anode fluid B is charged with chlorin, which reacts with soda solution,

l forming soluble hypochlorite b, according to The sodium hypochlorite in solutionin B is converted into the following in consequence of the continued formation of chlorin:

In the present case b and b may even act one Von another, forming hydrochloric acid as a by-product,

so that finally the anode fluid B always contains anexcess of free hypochlorous acid, which according to the foregoing is a great .drawbackin the carrying out of the process.

With -thereactions shown, which may take place in the diifusion of the caustic soda to the anodechamber, the series of possible transformations is not at all exhausted; but itis evident` without further explanation that where simple porous diaphragme are unconditionally used a, considerable quantity of caustic sodajmust pass over to the anodechamber'andthat it is also impossible to prevent chlorin and chlorin compounds from lpassing overto the cathode-chamber. It

was. evidently considerations of this kind which led to the use of twoporouspartitiops arrangedparallel with a small space filled with salt solution between'them .instead'of'a single partition. On this salt'solution pressure is exerted, andl thus lthe passing over of the caustic soda and chloriny into the other compartment is prevented. This process, however, is unable to be carried out technically, as so strong a pressure must be applied in order to obtain a practical result that it is dicult, if not impossible, to make suitable diaphragms of a suitable material. Their IOO to be considered, however, and that is that the more caustic ysoda is contained in the cathode liquid in the cathode-cell lo the greater will be the tendency it has'to pass over into the middle cell m, and therefore the greater must be' the counter-pressure in this cell. This may, for instan ce,be obtained by arranging several cathode-cells 7c in such a way that the cathode liquid (the caustic-soda contents of which constantly increases) flows through all the cells in succession and imparting to each of these cathode-cells in any suitable manner a higher dierence of pressure thanv the preceding one as compared with that of the middle cell m. The following means (shown in Fig. 2) may also be employed: Here the cathode-cell kis divided into several superimposed compartments, the uppermost of which receives the fresh chlorid-of-sodium solution, while by a suitable means of circulation, which will be hereinafter explained, care is taken that the lower compartments are supplied with liquid already containing a higher quan-V tity of caustic soda in such a way that the lowermost compartment shows the highest caustic-soda contents. In this manner there is obtained a suitable grading down of the counter-pressure exercised by the middle cell, corresponding to the varying caustic-soda contents. The action of this division into compartments is also supported bya variation in the thickness of the porous wall p of the separate superimposed compartments of the cell, as shown in Fig. 2, which wall separates the -cathode-chamber from the middle cell. A Very important result is also obtained by this arrangement-namely, that less liquid from the middle cell 'm penetrates into the cathodecell r, according to the increasing thickness ofthe wall. In the middle cell m a'metallic superoXid-tor instance, cobalt snperoxid, as already explained in the preliminary the'- oretical argument-is introduced, and this takes place, preferably, by saturating pieces of pumice with nitrate of cobalt, then rendering same incandescent, and then packing them looselyin the middle cell m. The further necessary heating of the liquid in this cell 'm takes place, preferably, outside the apparatus, as shown in Fig. 3. In this arrangement the salt water, which has become cool, leaves themiddle cell m through a pipe h, which communicates with a vessel c, into which fresh solution runs from a tap d. From the vessel c the solution flows to' a heatingy apparatus e of any suitable kind,from whence it is lifted to a feed-tank f, whichis arranged at a height determined according to the degrec of hydraulic pressure, as the solution returns again to the cell m from this tank through a pipe g. Such a quantity of salt solution is also withdrawn'from the pipe b of the middle cell m as is necessary for com-Y pleting the contents of the cathode-cells 7a, a valved or other regulated passage or pipe h being provided to allow liquidjto iiow into the lower partof the uppermost cell and from the place for the anode-cell a as that described for the middle cell m. -A pipe il, having an vupwardly-directed bend in which any escape.

of chlorin, owing to variations of the level of the liquid in the anode-cell @,is prevented,

leads to a device Z, which automatically rey places the salt contents of the solution, and

thence to a lifting device n, which feeds a tank o, from whence a pipeq conveys the return ilow of the liquid to the cell a. To complete the explanation `of the arrangement shown in Fig. 3, it must also be mentioned that hydrogen formed in the cathode-cells k escapes through a small pipe r and that there is also a pipe s for drawing off the chlorin escaping from the anode-cell a. The auodet itself'may, for instance, be a carbon anode. A largenumber of these arrangements, which are operated simultaneously, may be fed from the same tanks by. means of pipes common to all, and also the heating and salt-replenishing devices (e and Z) may simultaneously serve for a similar series of decomposing apparatuses.

In order to complete the explanation, a

complete form of construction of the apparatus is shown in vertical section in -F-ig. 4 and horizontal section in Fig. 5. It must irst be pointed out that the middle cellminstead ot' being bordered by two porous walls p and p may also be formed by a channel-like cell or a group of such channels being arranged i'n one wall formed of the porous ma-' terial. Further, the whole apparatus instead circular openings, which after the disks have'` been superimposed traverse also the entire height ofthe apparatus and as a wholeform passageswhich act as the middle cell m. By the choice of Various sizes of rings the differ'- ences in the thickness of the walls between the middle cells m and the various compartments of the cathode-cell a is obtained. Between the separate sections of the whole porous cell thus formed slate disks u are placed. These have similar pertorations and are of a similar diameter to the asbestos disks, thus allowing the anode-cell a and the passages m of the middle cell to pass through vthe entire apparatus. The porous cell rests ICO At the uniform distance from the" l ISO below also on a slate disk fu, forming the bottom ot' the anode-chamber ct. As it is also perforated in the manner shown, all the passages m may connect with an annular collecting-passage situated in a cast-metal piece forming a socket or foot and on which the whole apparatus Vis built. A pipe g leads from the annular passage to the feed apparatus, which corresponds to the tank f of Fig. 3. The cell is closed at the top by a piece of slate, which also is perforated to correspond to the asbestos disks. The central perforation corresponding to the anode-chamber d traverses the disk completely'. The continuations of the passages m extend, however, only up to half the height and communicate laterally with an annular space, which is formed partly by the piece of slate and partly by an outer casting. A pipe b conveys the chlorid-of-sodium solution flowing out from the passages m to the heating apparatus e, Fig. 3. In Figs. ltand 5 the connections of the electric current are designated by the letters yy and The cathode-cell 7c is formed of three superimposed cast-iron hollow cylinders, which correspond to the three sections of the porous partition, which vary in their outer diameter. They rest on slate pieces u and are so formed that they may be socketed one in the other like pipes. Perforated flanges cast on them allow of a firm connection by means of bolts adapted to be tightened up. By this means the necessary coherence isimparted to the porous cells, and the whole apparatus receives the necessary stability. The cylinder-walls form also the cathodes. In order to form a water-tight joint for the whole apparatus, the joints w are filled with a suitable material-sued for instance, as a molten mixture of tar and Portland cement-at'ter the parts of the apparatus have been put together. The anode t is in this case a hollow cylinder of carbon which carries at its upper end a lead cover closing the cell. All the rest will be readily understood by reference to Fig. 3.

The apparatus hereinbefore described may also be employed for the electrolysis of other alkaline chlorids.

I declare that what I claim is- 1. In an apparatus for the electrolysis of alkaline chlorids, an anode' -compartment, a cathode-compart1nent,comprising a plurality of separate cells superimposed upon and in communication with each other, andan intermediate compartment, said anode and cathode compartments being separated from said intermediate compartment by porous walls.

2. In an apparatus for the electrolysis of alkaline chlorids, an anode-compartment, a cathode-compartment comprising a plurality of separate cells superimposed one above another, and the upper portion of each cell being connected with the lower portion of the next lower cell by a pipe, and an intermediate compartment, said anode and cathode compartments being separated from said intermediate compartment by porous walls.

3. In an apparatus for the electrolysis of alkaline chlorids, an anode-compartment having a porous wall, a cathode-compartment comprising a plurality of separate cells, superimposed one upon another and each having a porous wall of greater density than the wall of the next cell thereabove, and an intermediate compartment.

4. In an apparatus for the electrolysis of alkaline chlorids, an anodecompartment, a cathode-compartment comprising a plurality of separate cells superimposed one above another, and the upper portion of each cell being connected with the lower portion of the next lower cell by a pipe, and an intermediate compartment,the said anode and cathode compartments being separated from said intermediate compartment by porous Walls, and the wall ot each separate cell comprising said cathode-compartment being thicker than the wall of the next compartment above it.

5. In an apparatus for the electrolysis of alkaline chlorids, an anode -compartment, a cathode-compartment, and an intermediate compartment, said compartments being formed by asbestos disks superimposed upon each other each disk having a central perforation, a plurality of perforations between said central perforation and its periphery, and a plurality of perforations adjacent to its periphery, so that when said disks are assembled the central perforations register together to form the anodecompartment, the intermediate perforations register together to form intermediate compartments, and the outer perforations register together to form cath ode-compartments.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

CHARLES FOURNIER.

IVitnesses:

VHERMANN CUNo'n,

L. H. MUNIER.

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