SYSTEM FOR ELECTROLYSING WATER (SOEC) OR FUEL-CELL STACK (SOFC) OPERATING UNDER PRESSURE, THE REGULATION OF WHICH IS IMPROVED

Abstract

A system regulating pressure of a reactor for hightemperature electrolysis or co-electrolysis (HTE) or to an SOFC fuel-cell stack operating under pressure. The operation of the system includes: regulating upstream of one of the chambers, a flow rate of moisture-containing gas DH to guarantee electrochemical stability of a preset operating point; and controlling pressure by virtue of valves arranged downstream of the stack, for regulating gases including the moisture-containing gas, and which are generally hot.

Claims

1-11. (canceled)

12. A system comprising: at least one first chamber in which a first gas, which is a potentially wet gas, is suitable for circulating; at least one first feed line configured to feed potentially wet gas to an inlet of the first chamber up to a maximum operating pressure P.sub.max, the first feed line comprising a first flow rate regulator configured to regulate a flow rate of the first gas D.sub.H between a zero value and a maximum value D.sub.H,max: at least one second chamber in which a second gas is suitable for circulating; at least one second feed line configured to feed the second gas to an inlet of the second chamber, the second feed line comprising a second flow rate regulator configured to regulate the flow rate of the second gas D.sub.O between a zero value and a maximum value D.sub.O,max; an enclosure in which the first and second chambers are housed, in which enclosure a third gas, as an equalizing gas, is suitable for circulating, the enclosure configured to operate under pressure of the equalizing gas up to the maximum operating pressure P.sub.max; a third feed line configured to feed an inside of the enclosure with equalizing gas, the third feed line comprising a third flow rate regulator configured to regulate a flow rate of the equalizing gas D.sub.air between a zero value and a maximum value D.sub.air,max; sensors for pressure configured to measure pressure in each of the first and second chambers and in the enclosure, between atmospheric pressure and the maximum pressure value P.sub.max; at least three regulating valves, arranged outside the enclosure and on an outlet line of the first chamber or chambers, of the second chamber or chambers, and of the enclosure, respectively, each valve configured to operate at a temperature greater than condensation temperature of the wet gas at the maximum pressure P.sub.max considered, each valve configured to be opened from 0% to 100% and having a capacity K.sub.v suited to the maximum pressure P.sub.max and to the average flow rate of the gas considered on each of the three outlet lines; means for heating the lines containing the wet gas to a temperature greater than the condensation temperature of the wet gas at the maximum pressure P.sub.max considered; command and automatic control means for commanding and automatically controlling the regulating valves as a function of differences in pressure values measured by the pressure sensors to obtain a minimum difference in pressure between the first chamber or chambers, the second chamber or chambers, and the enclosure; wherein, by including volume of the lines for circulating gas upstream and downstream of the enclosure and of the chambers, Vol.sub.H being volume of the first chamber or chambers, Vol.sub.O volume of the second chamber or chambers, and Vol.sub.air volume of the enclosure, the flow rate regulators are dimensioned to comply with the ratio: $\begin{array}{c}{\mathrm{Vol}}_H\\ D_{H,\max }\end{array}=\begin{array}{c}{\mathrm{Vol}}_O\\ D_{O,\max }\end{array}=\begin{array}{c}{\mathrm{Vol}}_{\mathrm{air}}\\ D_{\mathrm{air},\max }\end{array}.$

13. The system as claimed in claim 12, further comprising a condenser for the wet gas arranged downstream of the regulating valve on the outlet line of the first chamber or chambers.

14. The system as claimed in claim 12, wherein the command and automatic control means is further configured to command and automatically control the flow rate regulators for the second gas and for the equalizing gas as a function of an opening state of the regulating valves for the second gas and for the equalizing gas, to prevent complete opening or closing states of the valves for the second gas and for the equalizing gas.

15. The system as claimed in claim 12, further comprising a high-temperature electrolysis or co-electrolysis (HTE) reactor comprising a stack of solid oxide elementary (co-)electrolysis cells each comprising an anode, a cathode, and an electrolyte inserted between the anode and the cathode, the cells being electrically connected in series, the stack comprising two electric terminals for feeding current to the cells and defining chambers for circulating steam and hydrogen or steam, hydrogen and carbon dioxide (CO.sub.2) on the cathodes as first chambers, and chambers for circulating air or nitrogen or oxygen or a gas mixture containing oxygen on the anodes as second chambers.

16. The system as claimed in claim 12, further comprising a high-temperature fuel-cell (SOFC) stack comprising a stack of solid oxide elementary electrochemical cells each comprising an anode, a cathode, and an electrolyte inserted between the anode and the cathode, the cells being electrically connected in series, the stack comprising two electric terminals for cell current recovery and defining chambers for circulating dihydrogen or another fuel gas or a mixture containing a fuel gas on the anodes as first chambers and chambers for circulating air or nitrogen or oxygen or a gas mixture containing oxygen on the cathodes as second chambers.

17. The system as claimed in claim 12, comprising at least three sensors for absolute pressure configured to each measure pressure in each of the first chambers, in each of the second chambers, and in the enclosure, respectively.

18. The system as claimed in claim 12, comprising at least one sensor for absolute pressure P.sub.H, configured to each measure pressure in each of the first chambers, and comprising at least two differential sensors for pressure configured to measure the difference in pressure between the second chamber or chambers and the first chamber or chambers P.sub.O=(P.sub.OP.sub.H) and between the enclosure and the first chamber or chambers P.sub.air=(P.sub.airP.sub.H), respectively.

19. The system as claimed in claim 12, further comprising bypass valves each arranged in parallel with the regulating valves, respectively.

20. An operating method for the system as claimed in claim 12, comprising: a) defining following operating setpoints: a1) defining a flow rate D.sub.H that corresponds to quantity of potentially wet gas necessary for a predetermined electrochemical operating point; a2) defining a flow rate D.sub.O that corresponds to quantity of second gas necessary for a predetermined electrochemical operating point; a3) defining a flow rate D.sub.air that corresponds to quantity of second gas necessary for detection and safety with regard to the leaks and for preventing formation of an explosive atmosphere in the enclosure; a4) defining a pressure P.sub.setpoint for the predetermined operating point; a5) defining the differential pressure P.sub.O,setpoint corresponding to the deviation in pressures between that prevailing in the second chamber or chambers and that in the first chamber or chambers; a6) defining the differential pressure P.sub.air,setpoint corresponding to the deviation in pressures between that in the enclosure and that prevailing in the first chamber or chambers; b) using the following regulations: b1) actuating the wet gas flow rate regulator(s) to regulate the flow rate D.sub.H of the wet gas; b2) actuating the second-gas flow rate regulator(s) to regulate the flow rate D.sub.O entering the second chamber or chambers; b3) actuating the equalizing gas flow rate regulator(s) to regulate the flow rate D.sub.air entering the enclosure; b4) actuating the regulating valve V.sub.H for the wet gas to regulate the actual pressure P.sub.H of the first chamber or chambers to the setpoint value P.sub.setpoint; b5) actuating the valve V.sub.O for the second gas such that the actual differential pressure between the second chamber or chambers and the first chamber or chambers P.sub.O=(P.sub.OP.sub.H) is regulated as a function of the error measured with respect to the setpoint (P.sub.O,setpointP.sub.O), such that the pressure P.sub.O of the second gas follows that P.sub.H of the first chamber or chambers with the setpoint differential pressure P.sub.O,setpoint; b6) actuating the valve V.sub.air for the equalizing gas such that the actual differential pressure between the enclosure and the first chamber or chambers P.sub.air=(P.sub.airP.sub.H) is regulated as a function of the error measured with respect to the setpoint (P.sub.air,setpointP.sub.air), such that the pressure P.sub.air of the equalizing gas of the enclosure that P.sub.H of the first chamber or chambers with the setpoint differential pressure P.sub.air,setpoint.

21. The operating method as claimed in claim 20, further comprising a flow rate increasing for the second gas D.sub.O and for the equalizing gas D.sub.Air if the regulating valves for the second gas V.sub.O and for the equalizing gas V.sub.Air, respectively, are close to a complete closing state.

22. The operating method as claimed in claim 20, further comprising a flow rate reducing for the second gas D.sub.O and for the equalizing gas D.sub.Air if the regulating valves for the second gas V.sub.O and for the equalizing gas V.sub.Air, respectively, are close to a complete opening state.

Description

DETAILED DESCRIPTION

[0101] Other advantages and features of the invention will emerge more clearly upon reading the detailed description of examples for implementing the invention given by way of illustration and in a nonlimiting manner with reference to the following figures wherein:

[0102] FIG. 1 is a schematic view of an elementary electrochemical cell of a HTSE electrolyzer;

[0103] FIG. 2 is a schematic view of a stack of cells according to FIG. 1;

[0104] FIG. 3 is a schematic view of an electrochemical cell of an SOFC stack;

[0105] FIG. 4 is a schematic view of a system according to the invention comprising a HTE electrolyzer, the figures showing the sensors and flow rate regulators necessary for the regulation of pressure in the chambers for circulating the steam and hydrogen, the oxygen and in the enclosure under pressure which houses the chambers;

[0106] FIG. 5 is a schematic view of the sensors and flow rate regulators with the representation of the automatic control loops of the system according to FIG. 4;

[0107] FIG. 6 is a computer flow diagram of the pressure regulations according to the embodiment of FIG. 4;

[0108] FIG. 7 is a computer flow diagram of the regulation in accordance with the invention of the flow rate D.sub.O of the chambers for circulating oxygen as a function of the opening percentage of the valve V.sub.O in a high-temperature electrolysis module according to FIGS. 9-18;

[0109] FIG. 8 is a computer flow diagram of the regulation in accordance with the invention of the flow rate D.sub.air of the enclosure under pressure as a function of the opening percentage of the valve V.sub.air in a high-temperature electrolysis module according to FIGS. 9-18;

[0110] FIG. 9 is an exploded view of an embodiment of a HTE module according to the patent application filed in France on Dec. 18, 2014 under the no. 14 62699 and used as part of a system according to the invention;

[0111] FIG. 10 is a sectional view of the module assembled according to FIG. 9, the section being produced in the plane for circulating the equalizing gas, respectively;

[0112] FIG. 11 is a detail view of FIG. 10, showing the passage of the equalizing gas into the housing recesses for the device for insulation and sealing between the inside and outside of the module;

[0113] FIGS. 12 and 13 are sectional views of a module assembled according to FIG. 9, the section being produced in the plane for circulating the carried steam and the produced hydrogen, and in the plane for circulating the carried air and the produced oxygen, respectively;

[0114] FIG. 14 is an exploded view of an embodiment of a HTE reactor having a stack of two modules according to the patent application filed in France on Dec. 18, 2014 under the no. 14 62699 and used as part of a system according to the invention;

[0115] FIGS. 15, 16 and 17 are sectional views of a module assembled according to FIG. 14, the section being produced in the plane for circulating the carried air and the produced oxygen, in the plane for circulating the carried steam and the produced hydrogen, and finally in the plane for circulating the equalizing gas, respectively;

[0116] FIG. 18 is a view of the bottom of an electrolysis reactor according to FIGS. 14-17.

[0117] FIGS. 1-3 relating to the prior art have already been commented upon in the preamble. Therefore, they are not detailed hereafter.

[0118] For the sake of clarity, the same elements of a HTE reactor according to the prior art and of a HTE reactor which is used as part of a system according to the invention are designated by the same reference numbers.

[0119] It is specified in this case in the entirety of the present application that the terms lower, upper, top, bottom, inside, outside, internal, external are to be understood with reference to an interconnect according to the invention in a cross-sectional view along the symmetry axis X.

[0120] It is also specified that the terms upstream, downstream, inlet, outlet are to be considered with respect to the direction of circulation of the gases.

[0121] It is also specified that the modules of electrolyzers or of fuel-cell stacks described are of solid oxide type (SOEC meaning Solid Oxide Electrolyte Cell or SOFC, meaning Solid Oxide Fuel Cell) operating at high temperature.

[0122] Thus, all of the constituents (anode/electrolyte/cathode) of a cell for electrolysis or fuel-cell stack are ceramics. The operating high temperature of an electrolyzer (electrolysis reactor) or of a fuel-cell stack is typically between 600 C. and 950 C.

[0123] Typically, the characteristics of an SOEC elementary electrolysis cell suitable for the invention, of the cathode supported type (CSC), may be those indicated as follows in the table below.

TABLE-US-00001 TABLE Electrolysis cell Unit Value Cathode 2 Constituent material NiYSZ Thickness m 315 Thermal conductivity W m.sup.1 K.sup.1 13.1 Electrical conductivity .sup.1 m.sup.1 10.sup.5.sup. Porosity 0.37 Permeability m.sup.2 10.sup.13.sup. Tortuosity 4 Current density A .Math. m.sup.2 5300 Anode 4 Constituent material LSM Thickness m 20 Thermal conductivity W m.sup.1 K.sup.1 9.6 Electrical conductivity .sup.1 m.sup.1 1 10.sup.4.sup. Porosity 0.37 Permeability m.sup.2 10.sup.13.sup. Tortuosity 4 Current density A .Math. m.sup.2 2000 Electrolyte 3 Constituent material YSZ Thickness m Resistivity m 0.42

[0124] Referring to FIG. 4, the system according to the invention is pressure-regulated from the atmospheric pressure to a pressure chosen to be approximately 30 bar.

[0125] The system firstly comprises a high-temperature electrolysis or co-electrolysis (HTE) reactor comprising a stack 20 of solid oxide elementary (co-)electrolysis cells each comprising an anode, a cathode, and an electrolyte inserted between the anode and cathode, the cells being electrically connected in series, the stack comprising two electric terminals for feeding current to the cells and defining chambers 21 for circulating steam and hydrogen or steam, hydrogen and carbon dioxide (CO.sub.2) on the cathodes, and chambers 23 for circulating air or nitrogen or oxygen or a gas mixture containing oxygen on the anodes.

[0126] The system further comprises: [0127] a feed line that is suitable to feed steam to the inlet of the chambers 21 up to a maximum operating pressure P.sub.max, on which a flow rate regulator is arranged, which flow rate regulator is suitable for regulating the flow rate of the steam and of the produced hydrogen D.sub.H between a zero value and a maximum value D.sub.H,max; [0128] a feed line that is suitable to feed oxygen to the inlet of the chambers 23, on which a flow rate regulator is arranged, which flow rate regulator is suitable for regulating the flow rate of oxygen D.sub.O between a zero value and a maximum value D.sub.O,max; [0129] an enclosure 40 in which the stack 20 with the chambers 21, 23 thereof is housed, in which enclosure air as equalizing gas is suitable for circulating, the enclosure being suitable for operating under pressure up to the maximum operating pressure P.sub.max; [0130] a feed line suitable for feeding the inside of the enclosure with air, and on which a flow rate regulator is arranged, which flow rate regulator is suitable for regulating the flow rate of air D.sub.air between a zero value and a maximum value D.sub.air,max; [0131] sensors for pressure P.sub.H, P.sub.O, P.sub.air, which are suitable for measuring the pressure in the chambers 21, 23 and in the enclosure 40, between the atmospheric pressure and the maximum pressure value P.sub.max; [0132] at least three regulating valves V.sub.H, V.sub.O, V.sub.air, arranged outside the enclosure 40 and on the outlet line of the chambers 21, of the chambers 23 and of the enclosure 40, respectively, each valve being suitable for each operating at a temperature greater than the condensation temperature of the wet gas at the maximum pressure P.sub.max considered, each valve being suitable to be opened from 0% to 100% and having a capacity K.sub.v suited to the maximum pressure P.sub.max and to the average flow rate of the gas considered on each of the three outlet lines; [0133] means for heating the lines of the steam and of the produced hydrogen to a temperature greater than the condensation temperature of this wet gas at the maximum pressure P.sub.max considered; [0134] a condenser 50, arranged downstream of the regulating valve V.sub.H on the outlet line of the chambers 21; [0135] command and automatic control means for commanding and automatically controlling the regulating valves (V.sub.H, V.sub.O, V.sub.air) as a function of the differences in pressure values measured by the pressure sensors such as to obtain a minimum difference in pressure between the chambers 21, 23 and the enclosure 40.

[0136] By including the volume of the lines for circulating gas upstream and downstream of the enclosure and of the chambers, i.e. Vol.sub.H being the volume of the first chamber or chambers, Vol.sub.O the volume of the second chamber or chambers and Vol.sub.air the volume of the enclosure, the gas flowmeters (flow rate regulators) are preferably dimensioned to comply with the ratio:

[00003]$\frac{{\mathrm{Vol}}_H}{D_{H,\max }}=\frac{{\mathrm{Vol}}_O}{D_{O,\max }}=\frac{{\mathrm{Vol}}_{\mathrm{air}}}{D_{\mathrm{air},\max }}$

[0137] The command and automatic control means particularly comprise a microprocessor and PID (Proportional Integral Derivative) controllers.

[0138] The means for heating the various wet gas lines are particularly temperature-regulated heater cables.

[0139] Reference is now made to FIG. 5 which explains an example of regulating loops implemented automatically by a system according to the invention.

[0140] Beforehand, an operator responsible for the operation of the system defines operating setpoints.

[0141] The regulating loops according to the invention successively consist in: [0142] regulating, upstream of the stack 20, the flow rate of gas made up of a mixture of steam and hydrogen D.sub.H defined by the operator such as to ensure the stability of the operating point of the solid oxide cells; [0143] regulating, upstream of the stack 20, the flow rate of air D.sub.O defined by the operator such as to ensure the stability of the operating point of the solid oxide cells; [0144] regulating, upstream of the enclosure 40, the flow rate of air D.sub.air defined by the operator such as to ensure the safety of the system; [0145] regulating, to an operator setpoint P.sub.setpoint, the pressure of the hydrogen chambers 21 thanks to the regulating valve V.sub.H downstream of the stack 20; [0146] regulating, to an operator setpoint P.sub.O,setpoint, the deviation in pressure between oxygen and hydrogen chambers 23 and 21, P.sub.O=(P.sub.OP.sub.H) thanks to the regulating valve V.sub.O placed downstream of the stack 20; [0147] regulating, to an operator setpoint P.sub.air,setpoint, the deviation in pressure between the enclosure 40 and the hydrogen chambers 21, P.sub.air=(P.sub.airP.sub.H) thanks to the regulating valve V.sub.air at the outlet of the enclosure 40; [0148] periodically adjusting, by a step of 10%, the flow rate of oxygen D.sub.O if the valve V.sub.O closes at less than 5% or opens at more than 80%; [0149] periodically adjusting, by a step of 10%, the flow rate of air D.sub.air if the valve V.sub.air closes at less than 5% or opens at more than 80%.

[0150] For example, the setpoints defined by the operator may be as follows: [0151] flow rate of steam/hydrogen D.sub.H in the range from 0 to 10 l/h; [0152] flow rate of air D.sub.O in the range from 0 to 10 l/h; [0153] flow rate of air D.sub.air in the range from 0 to 100 l/h; [0154] P.sub.setpoint in the range from the atmospheric pressure to 30 bar; [0155] P.sub.O,setpoint in the range from 100 to 100 mbar, preferably 50 mbar; [0156] P.sub.air,setpoint in the range from 100 to +100 mbar, preferably 50 mbar in order to prevent the leakage of hydrogen in the enclosure 40 under pressure.

[0157] FIG. 6 gives the order and the detail of the regulations of the valves V.sub.O, V.sub.H implemented by PID modules: [0158] automatically controlling the regulating valve V.sub.H with respect to the deviation (P.sub.setpointP.sub.H); [0159] calculating the differential pressure P.sub.O=(P.sub.OP.sub.H); [0160] automatically controlling the regulating valve V.sub.O with respect to the deviation (P.sub.OP.sub.O,setpoint); [0161] calculating the differential pressure P.sub.air=(P.sub.airP.sub.H); [0162] automatically controlling the regulating valve V.sub.O with respect to the deviation (P.sub.OP.sub.O,setpoint).

[0163] The inventors have implemented the invention in an electrolysis reactor in accordance with the patent application filed in France on Dec. 18, 2014 under the no. 14 62699.

[0164] The detailed description of such a reactor having one or more modules M1, M2 is taken up again later with reference to FIGS. 9-18.

[0165] FIGS. 7 and 8 provide numerical values corresponding to the implementation of the invention in such a reactor.

[0166] More precisely, FIG. 7 gives the detail of the loop for regulating the flow rate of oxygen D.sub.O as a function of the opening state of the regulating valve V.sub.O: [0167] if V.sub.O<5% for 5 seconds, then D.sub.O is increased by 10%; [0168] if V.sub.O<3% for 2 seconds, then D.sub.O is increased by 10%; [0169] if V.sub.O>80% for 5 seconds, then D.sub.O is reduced by 10%; [0170] if V.sub.O>90% for 2 seconds, then D.sub.O is reduced by 10%.

[0171] FIG. 8 provides the detail of the loop for regulations of the flow rate D.sub.air as a function of the opening state of the valve V.sub.air: [0172] if V.sub.air<5% for 5 seconds, then D.sub.air is increased by 10%; [0173] if V.sub.air<3% for 2 seconds, then D.sub.air is increased by 10%; [0174] if V.sub.air>80% for 5 seconds, then D.sub.air is reduced by 10%; [0175] if V.sub.air>90% for 2 seconds, then D.sub.air is reduced by 10%.

[0176] The module M1 of the electrolysis reactor includes an elementary electrochemical cell (C1) having a shape axisymmetric about a central axis X, the cell being formed from a cathode, an anode, and an electrolyte inserted between the cathode and the anode, with two electric and fluid interconnects 5.1, 5.2 on either side of the cell.

[0177] The two interconnects 5.1, 5.2 are each produced from a single metal piece, preferably from ferritic steel having approximately 20% chromium, preferably from CROFER 22APU or F18TNb, or based on Inconel 600 or Haynes type nickel.

[0178] The upper interconnect 5.1 has, bored therethrough, a conduit 50 for carrying the steam, opening along the central axis onto the cell on the cathode side. As explained hereafter, there is provided a radial distribution of the carried steam and of the produced hydrogen up to a conduit 59 for covering the produced hydrogen, opening parallel to the central axis at the periphery of the cell on the cathode side.

[0179] The lower interconnect 5.2 has, bored therethrough, a conduit 51 for carrying draining gas, such as air, opening along the central axis onto the cell on the anode side. As explained hereafter, there is provided a radial distribution of the carried air and of the produced oxygen up to a conduit 54 for recovering the produced oxygen, opening parallel to the central axis at the periphery of the cell on the anode side.

[0180] A first sealing joint 61, having a shape axisymmetric about the central axis X, is arranged at the periphery of the elementary cell C1 and bearing at the same time against each of the two interconnects. This joint is provided to produce the seal around the cathode compartment.

[0181] A second sealing joint 63, having a shape axisymmetric about the central axis, is arranged at the periphery of the anode of the elementary cell and bearing at the same time against the lower interconnect and against the electrolyte. This joint is provided in order to produce the seal around the anode compartment. The sealing joints 61 and 63 are glass and/or vitroceramic-based, as is detailed later.

[0182] An electrical insulating and sealing device 8 having a shape axisymmetric about the central axis X is arranged at the periphery of the first sealing joint around the cathode compartment.

[0183] The device 8 is made up of an electrically insulating washer 80 forming a wedge, clamped by third and fourth metal sealing joints 81, 82 without contact therebetween. Each of these third and fourth joints 81, 82 is metal and bears against the upper and lower interconnect, respectively.

[0184] The lower interconnect 5.2 has, bored therethrough, at least one carrying conduit 58 for a gas, called an equalizing gas, and at least one recovering conduit 58 for this equalizing gas opening onto the annular space E defined between the joint 61 and the device 8 such as to produce an annular distribution of the equalizing gas in order to equalize the pressures on either side of the first sealing joint 61 during operation.

[0185] The device 8 is suitable for resisting a large differential in pressures between the pressure of the equalizing gas, that is carried thanks to the regulation according to the invention to the closest possible value to the operating pressure of the HTE reactor, typically from 10 to 30 bar, and the pressure outside the module, typically 1 bar. The insulating washer 80 makes it possible to prevent any short circuit between the lower interconnect 5.2 and the upper interconnect 5.1. Finally, the metal joints are suitable for having expansions compatible with the materials of the interconnects, particularly ferritic stainless steel-based interconnects.

[0186] In addition to what has already been described, the upper interconnect 5.1 has, bored therethrough, a carrying lateral conduit 52 opening into the carrying central conduit 50, as may be seen in FIG. 12. The upper interconnect also comprises an annular recess 53 for receiving the upper metal joint 81 and the insulating wedge 80 (FIGS. 10 and 11).

[0187] The lower interconnect 5.2 includes a bearing area on which both the second joint 63 and the elementary cell are positioned. From the immediate periphery of the cell outward, the lower interconnect 5.2 comprises an annular recess 54 for the radial flow of the mixture H.sub.2O/H.sub.2, a planar surface and another annular recess 55 concentric with that around the cell in order to receive the sealing device 8. The planar surface has, bored therethrough, a carrying lateral conduit intended to connect with the carrying central conduit 51 of the upper interconnect 5.1, as may be seen in FIG. 13.

[0188] As may be seen in FIG. 14, the planar surface of the lower interconnect is used as a support for the joint 61 and around the carrying lateral conduit 56. The joint 61 is made up of a mica ring 610 between two vitroceramic washers or rings 613, 614 each moreover bearing on the first 5.1 and the second 5.2 interconnects.

[0189] As may be seen in FIGS. 10 and 11, the lower interconnect has, bored therethrough, an annular recess 55 opening into the carrying 58 and recovering 58 conduits for the equalizing gas.

[0190] Each of the carrying 58 and recovering 58 conduits for the equalizing gas opens into the housing recess 55 for the sealing device 8 (FIGS. 10 and 11). According to the invention, there is provided a lateral mounting clearance for the sealing device 8 in the recesses 53, 55 of the upper 5.1 and lower 5.2 interconnect, respectively which is sufficient to allow the passage of the equalizing gas into the annular space (E) defined in this manner between device 8 and the inside of the recesses 53, 55. As may be seen in detail in FIG. 11, it is the passage produced at the end of boring the carrying conduit 58 inside the sealing device 8 which allows for the arrival of the equalizing gas in the annular space (E) and thus for the annular distribution of the latter. In a way, this annular distribution of the equalizing gas forms a peripheral curtain of gas around the reactive gas compartments, which makes it possible to equalize the pressures.

[0191] Thanks to the presence of the recesses 54, 57 for distributing the reactive gases on the lower interconnect 5.2, the module according to the invention with the two interconnects and the cell with geometry that is axisymmetric about the axis X allows the cell to be homogenously and radially fed with reactive gases regardless of the pressure level.

[0192] As illustrated in FIG. 9, an electrolysis module M1 may advantageously include electrical contact grids 9, 10 which may particularly have the effect of compensating for unevenness in order to obtain a better electrical contact between, firstly, the upper interconnect and the cathode and, secondly, between the lower interconnect and the anode.

[0193] Advantageously, as may be seen in FIG. 9, the module M1 may comprise, at the periphery of the insulating and sealing device 8, an electrically insulating ring 13, of the mica type, the ring 13 bearing on all of the areas where the two peripheral surfaces of the interconnects 5.1 and 5.2 face one another.

[0194] FIGS. 14-18 show a HTE reactor including two modules M1, M2 each produced like the module described above, which are stacked one upon the another.

[0195] In this reactor, the lower interconnect 5.2 of the upper module M1 and the upper interconnect 5.2 of the lower module M2 are produced from the same metal alloy component.

[0196] As may be seen in FIGS. 15 and 16, the various vertical and horizontal bores through the superposed interconnects 5.1-5.3 make it possible to produce, at the periphery then along the central axis X, the carrying conduits for air 51 (FIG. 15) and for steam 56, 50 (FIG. 16), respectively, and at the periphery for the recovering conduits, 54, for the produced oxygen and, 59, for the hydrogen, respectively, for each electrolysis cell C1, C2.

[0197] As may be seen in FIG. 17, the various vertical bores through the superposed interconnects 5.1-5.3 make it possible to produce, at the periphery, the carrying and recovering conduits 58 for the equalizing gas around each electrolysis cell C1, C2.

[0198] According to an advantageous embodiment, the module or the reactor according to the invention incorporates a bolt 11 mounted to pass through housings produced in the interconnects. As may be seen in FIGS. 10 and 17, the head 110 of the through-bolt 11 rests in a housing of an end interconnect 5.2 or 5.3 and a nut 111 screwed onto the through-bolt projects on the other end interconnect 5.1, the nut 111 indirectly bearing via a washer 112 on an electric insulating sleeve 12 mounted in the housing of the upper interconnect 5.2 or 5.1. The bolt 11 prevents the untimely opening of each module during the operation under pressure, which provides operating safety but not the compressive clamping of each cell between the interconnects. The clamping, which ensures the sealing and the electrical contact, is moreover produced by applying a well-suited compressive effort from one interconnect onto the other. The chains of dimensions of all of the components of the modules are determined in order to ensure squashing of the sealing joints 81, 82 at the periphery, and the possible squashing of the electric contact grids 9, 10. Typically, the squashing produced by clamping is a few dozen microns. Of course, it is ensured that the compressive clamping effort is adjusted when the pressure rises inside the module according to the invention.

[0199] Finally, several pipes are connected to the various gas carrying and recovering conduits produced in the interconnects in the following manner: [0200] a lateral-carrying pipe 14 for the equalizing gas is connected to the lateral-carrying conduit 58 of the lower interconnect 5.2 or 5.3, whereas a recovering pipe 15 for the equalizing gas is connected to the lateral-recovering conduit 58 of the lower interconnect (FIGS. 10, 17 and 18); [0201] an air central-carrying pipe 16 is connected to the carrying central pipe of the lower interconnect 5.2 or 5.3 (FIGS. 12, 13, 15 and 18), whereas a recovering pipe 19 for the produced oxygen is connected to the annular recess 57 of the lower interconnect 5.2 or 5.3 (FIGS. 12, 13, 15 and 18); [0202] a steam central-carrying pipe 17 is connected to the carrying lateral conduit of the lower interconnect 5.2 or 5.3 itself opening onto that of the upper interconnect 5.1 (FIGS. 13, 16 and 18), whereas a recovering pipe 18 for the produced hydrogen is connected to the lateral-recovering conduit 59 of the lower interconnect (FIGS. 13, 16 and 18).

[0203] The operation of a HTE reactor is now described, which reactor comprises several modules according to the invention which have just been described, the modules being stacked upon one another, like that shown in FIGS. 14-18.

[0204] Steam is fed to the pipe 17 and therefore the steam carrying conduits 56, 52 and 50 and simultaneously equalizing gas to the pipe 14 and therefore the carrying conduit 58 and the annular space E, the pressure of the carried steam being substantially equal to that of the equalizing gas.

[0205] Also simultaneously, the pipe 16 is fed with air, as draining gas, as is therefore the carrying conduit 51, the pressure of the carried air being substantially equal to that of the equalizing gas.

[0206] The steam distributed radially from the carrying conduit 50 and the hydrogen produced by the electrolysis of the steam circulates in the annular recess 54 and then is recovered radially in the recovering conduit 59 and therefore by the recovering pipe 18 (FIGS. 12 and 16).

[0207] The equalizing gas circulates in the annular space E and is recovered in the recovering conduit 58 and therefore by the recovering pipe 15 (FIGS. 10 and 17).

[0208] The air distributed radially from the carrying conduit 51 and the oxygen produced by the electrolysis of the steam circulates radially in the annular recess 57 and then is recovered by the recovering pipe 19 (FIGS. 13 and 15).

[0209] In the module M1 or the reactor with a stack of modules M1, M2 according to the invention, no feed current passes through all of the pipes 14-19.

[0210] Other alternatives and advantages of the invention may be carried out without necessarily departing from the scope of the invention.

[0211] The invention is not limited to the examples which have just been described; in particular it is possible to combine, with one another, features of the illustrated examples within non-illustrated alternatives.

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