Process for monitoring, protection and safety shut-down of an electrolyser system

Patent metadata

Field	Value
Publication number	US-10053788-B2
Application number	US-201314763226-A
Country	US
Kind code	B2
Filing date	Jan 25, 2013
Priority date	Jan 25, 2013
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

The invention concerns a process for monitoring failure situations related to feed and/or purge flow in electrolyzer cells, stacks or systems, said monitoring process being combined with appropriate actions to be taken in case of such failure situations, wherein (a) the current and/or the voltage are monitored and controlled over a single cell, over all the cells or over one or more selected cells in a stack or a system of stacks, (b) in case the current, the voltage or the ratio between voltage and current crosses its pre-defined threshold value, a failure mode is detected and communicated to the control system, and c) the voltage levels of the system are adjusted to be within safe limits (safe-mode limits).

First claim

The invention claimed is:

1. A process for monitoring failure situations in electrolyser cells, stacks or systems and taking preventive action, comprising
(a) monitoring and controlling current and/or voltage over a single stack, over all stacks, or over one or more selected stacks in an electrolyser system, with a control system also adapted to:
(1) monitor at least one of feed gas and purge gas flow in the single stack, in all the stacks or in a selected stack in the electrolyser system, and
(2) take preventive action comprising flushing potentially oxidized electrodes with oxygen-free gases, gradually cooling electrolyser cells, stacks or systems by flush gases or by passive heat loss, or maintaining the electrolysis voltage per cell over the cells and stacks, at least until cell temperatures are below the oxidation threshold of the electrolyser cell electrodes,

(b) monitoring or controlling the current and the voltage, and, when a ratio between voltage and current crosses a pre-defined threshold value, detecting and communicating a failure mode to the control system,
c) adjusting the voltage levels to be within safe limits (safe-mode limits) by applying a protective voltage of between 600 mV and 1500 mV per cell across each cell in the stack, and optionally taking at least one of the following preventive actions:
(1) flushing potentially oxidizing electrodes with oxygen-free gases,
(2) gradually cooling electrolyser cells, stacks or systems, either by flush gases or by passive heat loss from the system, and
(3) maintaining the electrolysis voltage per cell over the cells and stacks, at least until cell temperatures are below the oxidation threshold of the electrolyser cell electrodes.

2. A process according to claim 1 , wherein the electrolyser is a solid oxide electrolyser cell (SOEC).

3. A process according to claim 1 , wherein the protective voltage is applied until the temperature of the electrolyser cells, stacks or system is below 500° C.

4. A process according to claim 1 , comprising operating said electrolyser within an applied voltage range between 600 mV and 1500 mV per cell, in which case no changes in the applied voltage are necessary in case of failure.

5. A process according to claim 1 , further comprising monitoring both current and voltage to detect failures and to apply protective voltage levels in case of failure through the use of a common power supply unit.

6. A process according to claim 1 , wherein the preventive action includes a reduction of the flow rate of oxygen-containing gases to the cells, stacks or system.

7. A process according to claim 1 , wherein the preventive action includes flushing with a protective gas over one of or both electrodes of the electrolyser for a period of time to protect them from excessive product concentrations or to flush out oxygen.

8. A process according to claim 1 , wherein current through the cells is limited to below 0.1 A/cm 2 .

9. A process according to claim 1 , wherein the preventive action includes flushing with a protective gas around the cells, stacks or system until the temperature of the cells, stacks or system is below 500° C.

10. A process according to claim 9 , wherein the protective gas is a non-oxygen-containing inert gas, comprising N 2 .

11. A process according to claim 9 , wherein a feed side, oxygen side and surroundings of the stack are all flushed with an oxygen-free inert gas until the temperature of the stack is below 500° C.

12. A process according to claim 11 , wherein an inert gas is applied to the feed side at a pressure higher than that on the oxygen side and/or that on the external interfaces.

Assignees

• Haldor Topsoe As
• Haldor Topsoe As

Inventors

• Pedersen Claus Friis
• Bech Lone
• Heiredal-Clausen Thomas
• Jakobsson Niklas Bengt

Classifications

• C25B1/10

  Chemistry & Metallurgy · mapped topic

• C25B15/02 Primary

  Process control or regulation · CPC title

• C25B1/04

  by electrolysis of water · CPC title

• C25B9/73

  of the filter-press type · CPC title

• Y02E60/36

  Hydrogen production from non-carbon containing sources, e.g. by water electrolysis · CPC title