US3812026A

US3812026A - Pressurized electrolyzer including gas product-electrolyte separating means

Info

Publication number: US3812026A
Application number: US00220648A
Authority: US
Inventors: G Bertrand; P Perroud; Baron M Sylvestre
Original assignee: Commissariat a lEnergie Atomique CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 1971-01-26
Filing date: 1972-01-25
Publication date: 1974-05-21
Anticipated expiration: 1991-05-21
Also published as: GB1349690A; FR2126928B1; FR2126928A1

Abstract

The electrolyzer is constituted by a plurality of cylindrical unitary cells which are independent, leak-tight and withstand the rated pressure. The unitary cells are of the single-pole or double-pole type and are connected electrically in series, supplied in parallel with electrolyte and in turn supply two-phase mixtures in parallel to a spherical-head, constant-level separator.

Description

May 21, 1974 G. BERTRAND F-TAL 3,8 2,0 6

PRESSURIZED -ELECTROLYZER INCLUDING GAS PRQDUCT-ELECTRDLYTE SEPARATING MEANS 3 Sheets-Sheet 1 Filed Jan. 25. 197.2

Fig:2

fir 3 I r *f i i Fig 1 p May 21, 1914 G. BERTRAND ETAL 3,812,026

PRESSURIZ'ED ELECTROLYZER INCLUDING GAS PRODUCT-ELECTROLYTE SEPARATING MEANS Filed Jan. 25, 1972 5 Sheets-$heet 2 I 1 Ill HI I HI I May 21, 1974 PRESSURIZED ELECTROLY Filed Jan. 25, 1972 G. BERTRA D AL ,3 ZER INCLUDING GAS PRODUCT-ELECTROLYTE SEPARATING MEANS 3 Sheets-Sheet 5 "United States Patent Int. Cl. B01]: 3/00 US. Cl. 204-270 ABSTRACT OF THE DISCLOSURE The electrolyzer is constituted by a plurality of cylindrical unitary cells which are independent, leak-tight and withstand the rated pressure.

The unitary cells are of the single-pole or double-pole type and are connected electrically in series, supplied in parallel with electrolyte and in turn supply two-phase mixtures in parallel to a spherical-head, constant-level separator.

5 Claims This invention relates to a pressurized electrolyzer which has a high degree of reliability and is capable of undergoing substantial variations in trim and accelerations in a number of different directions without any loss of efficiency.

More particularly, the invention relates to a pressurized water electrolyzer which can be placed on board land, air or space vehicles or on board ships or submarines and employed as a source either of hydrogen or oxygen or alternatively of both these fluids at the same time.

The electrolysis of water or more precisely of acid or basic solutions is well known as an industrial source of hydrogen or oxygen. In order to obtain high yields with a suflicient degree of purity of the fluid or fluids produced, it is known to construct electrolyzers which process under pressure a concentrated potassium solution (25 to 30%) with high current densities (580 to 2500 a./m. and at high temperatures (6580 Q). As a rule, the pressure is low (less than 1 bar) although the Zdansky-Lonza technique makes it possible to work under a pressure of 30 bars.

All these electrolyzers of either the single-pole or double-pole type are compact units but are also heavy and voluminous. The only units which make it possible to operate under high pressure (Zdansky-Lonza technique) are of the filter-press type or in other words are constituted by a horizontal stack of electrodes and of diaphragms. This type of electrolyzer requires complete stoppage in order to permit the possibility of carrying out any repair on a single element (electrode or diaphragm). Finally, these electrolyzers which are designed for stable units do not lend themselves in any way of changes of trim or to accelerations.

This invention, which makes it possible to overcome these various disadvantages, relates to a pressurized electrolyzer which has a small weight, a small volume, a high degree of reliability, and is capable of operating in the event of damage to one or a number of elements and in the event of a change of trim or of various accelerations.

This electrolyzer is essentially characterized in that it is constituted by a plurality of single-pole or double-pole cylindrical unitary cells which are independent, leaktight and withstand the rated pressure, said unitary cells being connected electrically in series, supplied in parallel with electrolyte and adapted to supply two-phase mixtures in parallel to a spherical-head, constant-level separator.

Said electrolyzer is further characterized by the followmg points considered either separately or in any operafive-combinations:

each unitary cell comprises a positive electrode and a negative electrode which are separated by a diaphragm, said electrodes and said diaphragm being constituted by coaxial cylinders;

each unitary cell is constituted by a cylindrical shell which is closed at both ends by two plugs;

each plug is constituted by two electrically insulated and coaxial cylindrical sleeves, the inner sleeve which is secured to the internal electrode being provided with a central nozzle which serves as a current supply terminal and the outer sleeve which is in contact with the external electrode being provided with a peripheral nozzle and a current output terminal, these two sleeves being fitted one inside the other by means of an insulating end component which carries the diaphragm and being held in position by means of a closure nut which is screwed on said cylindrical shell;

each unitary cell is supplied with electrolyte through the central and peripheral nozzles of one of the plugs aforesaid;

each unitary cell delivers two-phase mixtures through the central noule and the peripheral nozzle of the other plug aforesaid;

the unitary cells are supplied in parallel by a pump for the circulation of the electrolyte;

the fluid-circuit for the distribution of the electrolyte is provided with a cell for the filtration of the entire quantity of electrolyte delivered;

the spherical-head, constant-level separator is constituted by a cylindrical outer shell which is closed by means of a plug at the lower end thereof and joined at the upper portion thereof to a spherical head provided with a top collector and at least one lateral collector and by a cylindrical inner shell joined at the top portion thereof to a spherical head which is in turn joined at the top portion thereof to a cylindrical supporting shell which is rigidly fixed to the top collector;

the spherical-head separator is provided with two temperature-regulating coils carried by said plug, one coil being placed internally of said inner shell, the other coil being placed externally of said inner shell and internally of said outer shell;

the bottom plug of the spherical-head separator is fitted with a nozzle for the discharge of electrolyte;

the top collector of the spherical-head separator is constituted by a sleeve which supports the cylindrical supporting shell and by a filter and is fitted with two peripheral nozzles for the delivery of each of the gases produced and with a central nozzle which carries a calibrated valve at the inner extremity thereof and serves to supply one of the two-phase mixtures produced;

each lateral collector of the spherical-head separator is constituted by a sleeve provided with at least one nozzle which carries a calibrated valve at the inner extremity thereof and serves to supply the other two-phase mixture produced;

the sleeve of at least one of the lateral collectors is additionally provided with a water supply pipe;

the water supply to the spherical-head separator is controlled in dependence on the level of electrolyte as measured by a level detector.

Further secondary features will become apparent from the following description of one example of construction of the pressurized electrolyzer in accordance with the invention as adapted to the case of electrolysis of water by means of single-pole unitary cells, reference being made to the accompanying drawings, in which:

FIG. 1 is an axial sectional view of a unitary cell;

FIG. 2 is a sectional view taken along line AA of FIG. 1 and showing a unitary cell;

FIG. 3 is an axial sectional view of the separator with spherical head;

FIG. 4 is a plan view of the electrical connection of the unitary cells;

FIG. 5 is a top view of the electrical connection of the unitary cells.

In the description of this example, the practical arrangements adopted must be considered as forming part of the invention, it being clearly understood that any equivalent arrangements could equally well be employed without thereby departing from this invention.

There is shown in FIG. 1 the unitary cell constituted by a cylindrical shell 1 fitted with two end-pieces such as 2 which are welded to the shell 1 and on which are fixed the seal plugs.

Said plugs are themselves constituted by a first inner sleeve 3 which is rigidly fixed to the anode 4 by welding, by a second outer sleeve which is itself made-up of a cathode ring 5 rigidly fixed to the cathode 6 by welding and of a cap 7, these two sleeves being fitted one inside the other by means of an insulating end component 8, said component being secured to the diaphragm 9 and maintained in position by the nut 10 which is screwed into the end-piece 2.

The inner sleeve 3 is also rigidly fixed to the cap 7 of the outer sleeve by means of the packing-gland seal 11 and studs such as the stud 12.

Said inner sleeve 3 is also provided with a nozzle 13 which communicates with the anode compartment 14 and is employed either for the admission of anolyte or for the delivery of the two-phase mixture of anolyte and oxygen. This nozzle 13 also serves as a positive terminal.

The cap 7 of the outer sleeve is provided with a peripheral nozzle 15 which communicates with the cathode compartment 18 by means of an annular recess 16 which is machined in said cap and by means of cylindrical ducts such as 17 which are machined in the cathode ring 5. Said nozzle 15 is used either for the admission of the catholyte or for the delivery of the two-phase mixture of catholyte and of hydrogen. The nozzle 15 can also serve as negative terminal but for reasons of ease of connection, it is preferable to arrange a special terminal 19 on the cap 7.

FIG. 2 serves to show one of the forms adopted for the faces of the anode 4 and the cathode 6 which delimit with the diaphragm 9 the anode compartment 14 and cathode compartment 18.

There is shown in FIG. 3 the spherical-head separator constituted by the outer cylindrical shell 20 which is closed at the lower end by the plug 21 and joined at its upper portion to the spherical head 22. This head 22 is provided with a top collector and with two lateral collectors. The top collector is constituted by a base element 23 which is welded to the spherical head 22 and on which is screwed a supporting sleeve 24. This sleeve 24 is closed-off by means of a plug .25 which is screwed onto this latter.

The inner cylindrical shell 26 is joined at its top portion to the spherical head 27 and this latter is in turn joined at its top portion to the cylindrical supporting shell 28 which is welded to the sleeve 24. A splash-head filter 29 is welded to the top portion of the shell 28.

Two heat-

transfer coils

30 and 31 which are secured to the plug 21 by means of their tube ends as designated respectively by the

references

32, 33 and 34, 35 serve to regulate the temperature of the electrolyte within the two compartments of the separator and to homogenize the concentrations.

The plug 21 is also fitted with a nozzle 36 for the discharge of electrolyte.

The sleeve 24 is fitted with a nozzle 37 for the delivery of dry hydrogen gas. The plug 25 is fitted with a peripheral nozzle 38 for the delivery of dry oxygen gas and with a central nozzle 39. This nozzle 39 is joined at one of its extremities by means of a series of ducts such as 40 and pipes such as 41 (corresponding in number to the unitary cells) to the nozzles such as 13 of the unitary cells which supply said nozzle 39 with a two-phase mixture of anolyte and oxygen. The other extremity of the nozzle 39 is fitted with a calibrated valve 42 constituted by a nozzle outlet seating 43 and a cone-point member 44 by a nozzle outlet by means of a calibrated restoring spring. The form of the components of said calibrated valve 42 also permits this latter to perform the function of mechanical-separator for the two-phase mixture. The cone-point member 44 is also provided with a rod 45 which performs the function of a sliding guide rod for a level detector 46.

Each lateral collector is constituted by a body 47 which is welded to the spherical head 22 and a cap .48 which is secured to the body 47 by means of studs (not shown). There are fixed on each cap 48 pipes such as 49 which open into ducts such as 50 (the number of pipes such as 49 multiplied by the number of lateral collectors being equal to the number of unitary cells). Each pipes such as 49 is connected to a nozzle 15 of a unitary cell which supplies said pipe with a two-phase mixture of catholyte and hydrogen. The body 47 is fitted with a nozzle 51 to which is fixed a calibrated valve such as the valve 42. At least one of the lateral collectors is provided with a cap 48 on which is fixed a pipe 52 which, by means of a duct 53, permits the introduction of feed water as regulated by the level detector 46.

Each pipe such as 41 or 49 is fitted with an isolating valve 54 for isolating a unitary cell in order to permit any useful intervention.

The connector-pipe 36 for the supply of electrolyte to the unitary cells is connected to a filtration system followed by a distributing pump for delivery into a dis tributor from which the electrolyte is brought to the

nozzles

13 and 15 for supplying the unitary cells by means of a corresponding number of pipes fitted with isolating valves. These elements which are in any case conventional have not been illustrated in the drawings.

FIG. 3 also shows a type of grouping of unitary cells around a spherical-head separator.

FIGS. 4 and 5 show the electrical connection in series of unitary cells by means of strips such as 55 which connect the anode 13 of one cell to the cathode 19 of the following cell.

By Way of example, an electrolyzer of this type, in which twenty-eight unitary cells are grouped together and the electrolyte employed is a 28% potassium solution maintained at C. and which operates at a pressure of 60 'bars with a rate of circulation of electrolyte within the cells of 10 cm./sec. and a current density of 10,000 a./m. makes it possible to obtain hydrogen and oxygen of 99.8% purity.

The electrolyzer in accordance with the invention has the following advantages:

It operates with a very high current density per unit surface area of diaphragm, which makes its overall size smaller than that of an electrolyzer of the filter-press p It is not technologically limited in pressure since use is made of solutions which, in other fields, are known to be reliable under several hundreds of bars;

It is highly reliable but, in the event of damage sustained by one cell, the electrolyzer remains operational as a result of easy isolation and ready replacemennt of the damaged cell;

It withstands substantial changes of trim without any difficulty (angles greater than 60) and accelerations of several G having various orientations.

What we claim is:

1. A pressurized electrolyzer essentially constituted by a plurality of cylindrical unitary cells which are independent, leak-tight and withstand the rated pressure, said unitary cells being connected electrically in series, means for supplying said cells in parallel with an electrolyte, a spherical-head, constant-level separator and means for connecting said cells and said separator and for bringing two-phase mixtures in parallel from said cells to said separator, wherein the spherical-head, constant-level separator is constituted by a cylindrical outer shell which is closed by means of a plug at the lower end thereof and joined at the upper portion thereof to a spherical head provided with a top collector and at least one lateral collector and by a cylindrical inner shell joined at the top portion thereof to a spherical head which is in turn joined at the top portion thereof to a cylindrical supporting shell rigidly fixed to the top collector; and two temperature-regulating coils carried by said plug, one coil being placed internally of said inner shell, the other coil being placed externally of said inner shell and internally of said outer shell, said plug being additionally fitted with a connector-pipe for the discharge of electroylte.

2. A pressurized electrolyzer according to claim 1, wherein the top collector is constituted by a sleeve which supports the cylindrical supporting shell and by a filter and is fitted with two peripheral nozzles for the delivery of each of the gases produced and with a central nozzle which carries a calibrated valve at the inner extremity thereof and serves to supply one of the two-phase mixtures produced.

3. A pressurized electrolyzer according to claim 1, wherein each lateral collector is constituted by a sleeve provided with at least one nozzle which carries a calibrated valve at the inner extremity thereof and serves to supply the other two-phase mixture produced.

4. A pressurized electrolyzer according to claim 1, wherein at least one of the lateral collectors is provided with a water supply pipe.

5. A pressurized electrolyzer according to claim 4, wherein the water supply is controlled in dependence on the level of electrolyte as measured by a level detector.

References Cited UNITED STATES PATENTS 3,379,634 4/1968 Rutkowski 204-258 3,330,755 7/1967 Mahany 204--258 2,695,874 11/1954 Zdansky 204-258 3,255,574 6/1966 Glasgow 174 1,416,632 5/1922 Fothergill 55-52 W. I. SOLOMON, Assistant Examiner JOHN H. MACK, Primary Examiner U.S. Cl. X.'R.