US-12618161-B2 - High temperature electrolyser system optimized by increasing the pressure at the electrolyser output

US12618161B2US 12618161 B2US12618161 B2US 12618161B2US-12618161-B2

Abstract

A system including a high temperature electrolyser, a first supply line of the electrolyser configured to supply steam, a first discharge line of the electrolyser configured to discharge dihydrogen, a second discharge line of the electrolyser configured to discharge dioxygen, a first heat exchange module configured to provide heat exchange between the first supply line and the first discharge line, and a steam generator arranged on the first supply line and configured to produce steam from liquid water. The system also includes a module for recovering thermal energy from the dihydrogen at the output of the module for the benefit of the first steam supply line, the module having a compressor arranged in the first discharge line and configured to compress the dihydrogen, and a first heat exchanger arranged between the first supply line and the first discharge line to transmit thermal energy of the compressed dihydrogen to liquid water.

Inventors

Pierre Dumoulin
Nicolas Tauveron
GUILLAUME MONTZIEUX
Vincent Lacroix
Brigitte GONZALEZ
Jean-Baptiste LOPEZ-VELASCO

Assignees

COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

Dates

Publication Date: 20260505
Application Date: 20211025
Priority Date: 20201030

Claims (18)

1 . A system comprising: a high temperature electrolyser, a first supply line of the electrolyser configured to supply steam to the electrolyser, a first electrolyser discharge line configured to discharge dihydrogen from the electrolyser, a second electrolyser discharge line configured to discharge dioxygen from the electrolyser, a first heat exchange module configured to provide heat exchange between the first supply line and the first electrolyser discharge line, a steam generator arranged on the first supply line upstream of the first heat exchange module and configured to produce steam from liquid water, and an energy recovery module for recovering thermal energy from the dihydrogen at an output of the first heat exchange module for benefit of the first supply line, the energy recovery module comprising: a compressor arranged on the first electrolyser discharge line downstream of the first heat exchange module and configured to compress the dihydrogen, and a first heat exchanger arranged on the first supply line to receive liquid water, upstream of the steam generator, and on the first electrolyser discharge line, downstream of the compressor, so as to transmit thermal energy of the compressed dihydrogen to the liquid water, wherein the system comprises a second electrolyser supply line configured to supply air to the electrolyser and a third heat exchanger arranged on the first electrolyser discharge line, downstream of the first heat exchanger of the energy recovery module, to heat only air entering the second electrolyser supply line using heat only from the dihydrogen in the first electrolyser discharge line.
2 . The system according to claim 1 , comprising a second heat exchanger arranged between the second electrolyser discharge line and the first supply line, upstream of the steam generator, to transmit the thermal energy of the dioxygen to the liquid water upstream of the steam generator.
3 . The system according to claim 2 , wherein the second heat exchanger is arranged downstream of the first heat exchanger on the first supply line.
4 . The system according to claim 2 , wherein the second heat exchanger and the first heat exchanger arranged on the first supply line, upstream of the steam generator, are associated in a three-fluid heat exchanger.
5 . The system according to claim 1 , comprising a second heat exchange module configured to provide heat exchange between the second electrolyser supply line and the second electrolyser discharge line.
6 . The system according to claim 1 , comprising a compressor arranged on the second electrolyser supply line and configured to compress air.
7 . The system according to claim 1 , wherein the first heat exchange module comprises fourth and fifth heat exchangers designed to operate at different temperatures.
8 . The system according to claim 7 , wherein the fourth heat exchanger is located upstream of the fifth heat exchanger on the first electrolyser discharge line and operates at a temperature higher than a temperature of operation of the fifth heat exchanger.
9 . The system according to claim 7 , wherein the first heat exchange module is designed to operate at a temperature of dihydrogen exiting the electrolyser.
10 . The system according to claim 1 , comprising a liquid/gas separator arranged downstream of the third heat exchanger configured to condense water from the dihydrogen.
11 . The system according to claim 1 , comprising: a first liquid/gas separator arranged downstream of the third heat exchanger on the first electrolyser discharge line configured to condense water from the dihydrogen; a second compressor arranged downstream of the first liquid/gas separator configured to compress the dihydrogen from the first liquid/gas separator; and a second liquid/gas separator configured to condense water from the dihydrogen compressed by the second compressor.
12 . The system according to claim 11 , comprising a water feed line arranged to supply the water condensed by the second liquid/gas separator to the first heat exchanger.
13 . The system according to claim 11 , wherein the compressor is configured to heat the compressed dihydrogen and transfer the heated, compressed dihydrogen to the first heat exchanger.
14 . The system according to claim 5 , wherein the second heat exchange module comprises sixth and seventh heat exchangers designed to operate at different temperatures.
15 . The system according to claim 14 , wherein the sixth heat exchanger is located upstream of the seventh heat exchanger on the first electrolyser discharge line and operates at a temperature higher than a temperature of operation of the seventh heat exchanger.
16 . The system according to claim 2 , comprising a second heat exchange module configured to provide heat exchange between the second electrolyser supply line and the second electrolyser discharge line, wherein the second heat exchanger is configured to receive the dioxygen discharged from the second heat exchange module on the second electrolyser discharge line.
17 . The system according to claim 2 , wherein: the first heat exchanger is connected directly to the second heat exchanger via the first supply line, and the second heat exchanger is connected directly to the steam generator via the first supply line.
18 . The system according to claim 1 , wherein a temperature of the dihydrogen exiting the first heat exchanger is the same as a temperature of the dihydrogen exiting the first heat exchange module.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to the field of High Temperature water Electrolysis (HTE) or High Temperature Steam Electrolysis (HTSE), also with Solid Oxide Electrolyte Cells (SOEC) and Solid Oxide Fuel Cells (SOFC). It is particularly useful for optimising the energy consumption of an SOEC electrolyser system. PRIOR ART The electrolysis of water is an electrolytic reaction which breaks down water into dioxygen and dihydrogen gas by using an electric current according to the reaction: H2O→H2+½O2. For the electrolysis of water, it is advantageous to perform it at a high temperature of typically between 600 and 950° C., as some of the energy needed for the reaction can be provided by heat which is cheaper than electricity and the activation of the reaction is more effective at a high temperature and does not require a catalyst. A solid oxide electrolyte cell (SOEC) comprises in particular:—a first porous conductive electrode, or “cathode”, intended to be supplied with steam for the production of dihydrogen, —a second porous conductive electrode, or “anode”, through which the dioxygen produced by the electrolysis of the water injected onto the cathode escapes, and—a solid oxide membrane (dense electrolyte) sandwiched between the cathode and the anode, the membrane being anionically conductive at high temperatures, usually temperatures above 600° C. By heating the cell to at least this temperature and by injecting an electric current I between the cathode and the anode, there is a reduction of water at the cathode, which generates dihydrogen (H2) at the cathode and dioxygen at the anode. To perform high temperature steam electrolysis HTSE, steam H2O is injected into the cathodic compartment. From the effect of the current applied to the cell, the dissociation of water molecules in vapour form occurs at the interface between the hydrogen electrode (cathode) and the electrolyte; this dissociation produces dihydrogen gas H2 and oxygen ions. The dihydrogen is collected and discharged at the output of the hydrogen compartment. The oxygen ions migrate through the electrolyte and recombine into dioxygen O2 at the interface between the electrolyte and the oxygen electrode (anode). For the effective implementation of stack electrolysis, the stack is heated to a temperature above 600° C., usually a temperature of between 600° C. and 950° C., the gas supply is switched on at a constant flow rate, and an electrical power source is connected between two terminals of the stack in order to make the current I circulate there. The efficiency of the electricity to hydrogen conversion is a key point, in order to ensure the competitiveness of the technology. Most of the electricity consumption takes place during the electrolysis reaction itself, but about 30% of the electrolyser's consumption comes from the thermal/hydraulic fluid management system. This relates to the external architecture of the electrolyser and the management of fluids and thermal energy within this architecture. The evaporation of the water used in the electrolyser causes the highest energy consumption in this thermal/hydraulic management system. Typically, this function is performed by an electric steam generator which consumes 20% of the total consumption of the electrolyser. Furthermore, generally a significant amount of energy is released into the surrounding environment. For example, during the drying phase of the hydrogen and its compression, it is necessary to cool down this mixture strongly to allow the condensation of the water present in the water/hydrogen mixture. This condensation mostly takes place at a temperature lower than the evaporation temperature of the water at the inlet to the electrolyser, which means that very little of this condensation energy can be used. It is therefore necessary to minimise this consumption by optimising the architecture and the fluid management of the electrolyser system. It is therefore an object of the present invention to provide an optimised high temperature electrolyser system. Further objects, features and advantages of the present invention will become apparent from the following description and the accompanying drawings. It is understood that other advantages may be included. SUMMARY OF THE INVENTION To achieve this objective, according to one embodiment, the invention provides a system comprising a high temperature electrolyser (HTE), a first electrolyser supply line configured to supply steam to the electrolyser, a first electrolyser discharge line configured to discharge dihydrogen from the electrolyser, a second electrolyser discharge line configured to discharge dioxygen from the electrolyser, a first heat exchange module configured to provide a thermal exchange between the first steam supply line and the first dihydrogen discharge line, a steam generator arranged in the first steam supply line, upstream of the first heat exchange module, and configured to produce stea