System for regulating the temperature and pressure of a high-temperature electrolyser (SOEC) reversibly operating as a fuel cell stack (SOFC)
The invention relates to a system able to operate reversibly as an SOFC fuel-cell stack or as an SOEC electrolyser. According to the invention, a bypass line or circuit is provided in order to divert if needs be some of the hot gases issued from the chambers referred to as oxygen chambers (anodic chambers in SOEC mode, cathodic chambers in SOFC-stack mode) as this will cool the heat exchanger provided in the circuit through which the oxygen flows.
1. A system, comprising:
a high-temperature electrolysis or co-electrolysis reactor comprising a stack of individual solid oxide (co-)electrolysis cells each comprising a cathode, an anode, and an electrolyte inserted between the anode and the cathode, the cells being electrically connected in series, the stack comprising two electrical terminals for supplying current to the cells and defining, on the cathodes, first flow chambers and, on the anodes, second flow chambers;
at least one first supply line, capable of supplying the inlet of the first chambers with a mixture of steam and hydrogen or with a mixture of steam, hydrogen and carbon dioxide (CO 2 ), at a flow rate D H ;
at least one second supply line, capable of supplying the inlet of the second chambers with air or with oxygen or with a mixture of oxygen-containing gases, at a flow rate D o ;
at least one first discharge line, capable of discharging hydrogen produced at an outlet of the first chambers;
at least one second discharge line, capable of discharging oxygen produced at an outlet of the second chambers;
a first heat exchanger, arranged between the second supply line and the second discharge line, so as to recover heat from gases leaving the second chambers and transfer the heat to gases entering these same chambers in order to preheat said gases;
a bypass line of the second discharge line, arranged between the inlet and the outlet of the exchanger, so as to divert all or some of the gases from the outlet of the second chambers, the portion or all of the gases diverted not then flowing through the exchanger; and
a flow control valve, capable of allowing through a flow rate of from 0 to 100%, arranged on the bypass line.
2. The system as claimed in claim 1 , which operates reversibly in electrolysis mode, and in fuel cell mode, optionally with internal methane reforming.
3. The system as claimed in claim 1 , further comprising
a second heat exchanger, arranged between the first supply line and the first discharge line, so as to recover heat from the gases leaving the first chambers and transfer the heat to the gases entering these same chambers in order to preheat said gases.
4. The system as claimed in claim 3 , further comprising
a second flow control valve, capable of controlling a flow rate of from 0 to 100%, arranged on the first discharge line downstream of the outlet of the second heat exchanger.
5. The system claim 4 , further comprising
a condenser arranged upstream of the second valve and sized in order to remove steam from a gas mixture flowing in the first discharge line of the first chambers, and to enable operation of the second valve at a cooled temperature.
6. The system as claimed in claim 1 , further comprising
a third flow control valve, capable of controlling a flow rate of from 0 to 100%, arranged on the second discharge line downstream of the outlet of the first heat exchanger.
7. The system as claimed in claim 6 , further comprising
a cooler arranged between the bypass line and the second discharge line of the second chambers, and upstream of the first and third valve, the cooler being sized so as to cool the gas mixture flowing both in the bypass line and in the second discharge line and to enable operation of said first and third valves at a cooled temperature.
8. The system as claimed in claim 7 , wherein the cooler is a condenser comprising a device for purging condensed liquid water.
9. The system as claimed in claim 1 , further comprising
a first external heat source arranged on the first supply line at the inlet of the first chambers, optionally downstream of the second heat exchanger, to provide additional heat, in order to supplement the heating of the gases on said first supply line.
10. The system as claimed in claim 1 , further comprising
a second external heat source arranged on the second supply line at the inlet of the second chambers, and downstream of the first heat exchanger, to provide additional heat, in order to supplement the heating of the gases on said second supply line.
11. A system, comprising:
a high-temperature fuel cell comprising a stack of individual solid oxide 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 electrical terminals for recovering current from the cells and defining, on the anodes, first flow chambers and, on the cathodes, second flow chambers;
at least one first supply line, capable of supplying the inlet of the first chambers with dihydrogen or with another fuel gas or a mixture containing a fuel gas, at a flow rate D H;
at least one second supply line, capable of supplying the inlet of the second chambers with air or with oxygen or with a mixture of oxygen-containing gases, at a flow rate D o ;
at least one first discharge line, capable of discharging excess dihydrogen or other fuel at an outlet of the first chambers;
at least one second discharge line, capable of discharging excess air or oxygen or mixture of oxygen-containing gases at an outlet of the second chambers;
a first heat exchanger, arranged between the second supply line and the second discharge line, so as to recover heat from the gases leaving the second chambers and transfer the heat to the gases entering these same chambers in order to preheat said gases;
a bypass line of the second discharge line, arranged between the inlet and the outlet of the exchanger, so as to divert all or some of the gases from the outlet of the second chambers, the portion or all of the gases diverted not then flowing through the exchanger; and
a first flow control valve, capable of controlling a flow rate of from 0 to 100%, arranged on the bypass line.
12. The system as claimed in claim 11 , further comprising
a second heat exchanger, arranged between the first supply line and the first discharge line, so as to recover heat from the gases leaving the first chambers and transfer the heat to the gases entering these same chambers in order to preheat said gases.
13. The system as claimed in claim 11 , further comprising
a first external heat source arranged on the first supply line at the inlet of the first chambers, optionally downstream of the second heat exchanger, to provide additional heat, in order to supplement the heating of the gases on said first supply line.
14. The system as claimed in claim 11 , further comprising
a second external heat source arranged on the second supply line at the inlet of the second chambers, and downstream of the first heat exchanger, to provide additional heat, in order to supplement the heating of the gases on said second supply line.