Method and system for eliminating reverse current decay in fuel cells

Patent metadata

Field	Value
Publication number	US-2017200959-A1
Application number	US-201515320824-A
Country	US
Kind code	A1
Filing date	Jun 29, 2015
Priority date	Jun 30, 2014
Publication date	Jul 13, 2017
Grant date	—

Abstract

The invention relates to a system and a method for eliminating reverse current decay in the fuel cells. According to the invention, the system comprises
a fuel cell having an anode and a cathode; a fuel feed system for supplying the anode of the fuel cell with fuel and forming an anode system; a bypass line fitted in parallel and in flow connection with said anode system and capable of circulating fuel past the anode; an oxygen reduction unit; and a pressure unit for circulating gas in at least part of said anode system and said bypass line.

The bypass line is adapted to receive and circulate a flow of hydrogen during a fuel cell shutdown in order to mix the hydrogen with any oxygen present in the anode system, and to remove the oxygen from the anode system in said oxygen reduction unit by catalytic conversion. A control unit for receiving sensing signals representative of the state of the oxygen reduction process and controlling the amount of hydrogen passing through the system in response to said sensor is also described.

First claim

1 . A system for eliminating reverse current decay in the fuel cells, comprising:
a fuel cell having an anode and a cathode; a fuel feed system for supplying the anode of the fuel cell with fuel and forming an anode system; a bypass line fitted in parallel and in flow connection with said anode system and capable of circulating fuel past the anode; an oxygen reduction unit; and a pressure unit for circulating gas in at least part of said anode system and said bypass line;
wherein the bypass line is adapted to receive and circulate a flow of hydrogen during a fuel cell shutdown in order to mix the hydrogen with any oxygen present in the anode system, and to remove the oxygen from the anode system in said oxygen reduction unit by catalytic conversion.

2 . The system according to claim 1 , wherein the oxygen reduction unit is disposed in said bypass line.

3 . The system according to claim 1 , wherein the oxygen reduction unit in said bypass line is combined with a slipstream filter for removing impurities from the gas flow.

4 . The system according to claim 1 , wherein the bypass line is fitted between the main anode fuel feed line and the fuel return line in a loop.

5 . The system according to claim 1 , wherein said fuel feed line is branched from the main fuel line for the fuel cell and provided with a valve for feeding an appropriate amount of hydrogen to the oxygen reduction unit in order to catalytically convert the oxygen present in the anode system into water.

6 . The system according to claim 5 , wherein the system further comprises a control unit for receiving sensing signals representative of the state of the oxygen reduction process in said oxygen reduction unit from at least one sensor, and wherein the control unit in response to said sensor signals controls the amount of hydrogen passing through said valve.

7 . A method for minimizing the amount of oxygen present in an anode system of a fuel cell during shutdown, comprising the steps of:
providing a fuel cell with a cathode and an anode and a fuel feed system for the anode forming an anode system; providing a bypass line fitted in parallel and in flow connection with said anode system capable of circulating fuel past the anode; feeding during a fuel cell shutdown condition a flow of hydrogen into said bypass line in order to mix the hydrogen with any oxygen present in the anode system: circulating the gas flow in at least part of said anode system and said bypass line to an oxygen reduction unit; and reducing in said oxygen reduction unit any oxygen present in the anode system by catalytic conversion.

8 . The method according to claim 7 , further comprising the additional step of filtering the gas in said bypass line in order to remove any impurities from the gas flow.

9 . The method according to claim 7 , wherein gas in said bypass line is circulated in a loop including the main anode fuel feed line and the fuel return line.

10 . The method according to claim 7 , wherein an appropriate amount of hydrogen is fed to the oxygen reduction unit in order to catalytically convert the oxygen present in the anode system into water.

11 . The method according to claim 10 , further comprising the step of receiving sensing signals representative of the state of the oxygen reduction process in said oxygen reduction unit from at least one sensor, and controlling in response to said sensor signals the amount of hydrogen fed to the oxygen reduction unit.

Assignees

• Teknologian Tutkimuskeskus Vtt Oy

Inventors

• Ihonen Jari

Classifications

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/04228

  during shut-down · CPC title

• H01M8/04776

  at auxiliary devices, e.g. reformer, compressor, burner · CPC title

• H01M8/0687

  Reactant purification by the use of membranes or filters · CPC title

• H01M8/04097 Primary

  with recycling of the reactants (H01M8/04119, H01M8/04104 take precedence) · CPC title