US 5,366,818 AGranted

Solid polymer fuel cell systems incorporating water removal at the anode

AssigneeBallard Power Systems Inc.

InventorsDavid P. Wilkinson, Henry H. Voss, David S. Watkins, Keith B. Prater

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Abstract

A solid polymer fuel cell electric power generation system removes a substantial portion of water accumulated at the cathode in the outlet fuel stream of the anode. The system permits the operation of a hydrogen/oxygen fuel cell in a dead-ended mode where substantially pure oxygen is employed as the oxidant supply or using low oxygen stoichiometry where a dilute oxidant source, such as oxygen-containing air, is employed as the oxidant supply. The system thereby eliminates the need for an oxygen recirculation pump in systems operating on substantially pure oxygen, and substantially reduces the parasitic load to pressurize the oxidant stream in systems operating on dilute oxidant streams.

Claims54

Dependent claims

An electric power generation system comprising:

(A) a hydrogen-containing inlet fuel stream;
(B) an oxygen-containing inlet oxidant stream;
(C) a fuel cell stack comprising at least one fuel cell comprising:
(1) an anode having an inlet for directing said inlet fuel stream to the catalytically active portion of said anode, said anode producing cations from said fuel stream and an outlet fuel stream;
(2) a cathode having an inlet for directing said inlet oxidant stream to the catalytically active portion of said cathode, said cathode producing anions from said oxidant stream, said anions reacting with said cations to form water at said cathode;
(3) a cation exchange membrane interposed between said anode and said cathode, said membrane facilitating the migration of cations from said anode to said cathode and isolating said inlet fuel stream from said inlet oxidant stream;
and
(4) an electrical path for conducting electric current between said anode to said cathode;
and
(5) means for maintaining the partial pressure of water vapor in said outlet fuel stream below the saturation pressure of water vapor contained therein;
(D) a water separator for removing water from said outlet fuel stream to produce a dehumidified fuel stream and a removed water stream;
whereby a substantial portion of water accumulated at said cathode is absorbed in said outlet fuel stream.

9 more elements

An electric power generation system comprising:

(A) a hydrogen-containing inlet fuel stream;
(B) an oxygen-containing inlet oxidant stream;
(C) an inlet coolant water stream;
(D) a humidification assembly comprising:
(1) at least one fuel humidification section comprising a fuel humidification water supply and means for imparting water vapor from said fuel humidification water supply to said inlet fuel stream to produce a humidified fuel stream;
(2) at least one oxidant humidification section comprising an oxidant humidification water supply and means for imparting water vapor from said oxidant humidification water supply to said inlet oxidant stream to produce a humidified oxidant stream;
(E) a fuel cell stack comprising:
(1) an electrochemically active section comprising at least one fuel cell, said fuel cell comprising:
(a) an anode having an inlet for directing said humidified fuel stream to the catalytically active portion of said anode, said anode producing cations from said humidified fuel stream and an outlet fuel stream;
(b) a cathode having an inlet for directing said humidified oxidant stream to the catalytically active portion of said cathode, said cathode producing anions from said humidified oxidant stream, said anions reacting with said cations to form water at said cathode;
(c) a cation exchange membrane interposed between said anode and said cathode, said membrane facilitating the migration of cations from said anode to said cathode and isolating said humidified fuel stream from said humidified oxidant stream;
and
(d) an electrical path for conducting electric current between said anode to said cathode, and
(e) means for maintaining the partial pressure of water vapor in said outlet fuel stream below the saturation pressure of water vapor contained therein;
(2) at least one coolant passage having an inlet for directing said inlet coolant water stream into thermal contact with said electrochemically active section to absorb heat generated within said active section and produce an outlet coolant water stream;
(F) a heat exchanger for removing heat from said outlet coolant water stream to produce a chilled coolant water stream;
(G) a water separator for removing water from said outlet fuel stream to produce a dehumidified fuel stream and a removed water stream;
(H) a reservoir for receiving said removed water stream from said water separator and said chilled coolant water stream from said heat exchanger;
wherein said inlet coolant water stream is drawn from said reservoir, and whereby a substantial portion of water accumulated at said cathode is absorbed in said outlet fuel stream.

16 more elements

An electric power generation system comprising:

(A) a hydrogen-containing inlet fuel stream;
(B) an oxygen-containing inlet oxidant stream;
(C) a humidification assembly comprising:
(1) at least one fuel humidification section comprising a fuel humidification water supply and means for imparting water vapor from said fuel humidification water supply to said inlet fuel stream to produce a humidified fuel stream;
(2) at least one oxidant humidification section comprising an oxidant humidification water supply and means for imparting water vapor from said oxidant humidification water supply to said inlet oxidant stream to produce a humidified oxidant stream;
(D) a fuel cell stack comprising:
(1) an electrochemically active section comprising at least one fuel cell, said fuel cell comprising:
(a) an anode having an inlet for directing said humidified fuel stream to the catalytically active portion of said anode, said anode producing cations from said humidified fuel stream and an outlet fuel stream;
(b) a cathode having an inlet for directing said humidified oxidant stream to the catalytically active portion of said cathode, said cathode producing anions from said humidified oxidant stream, said anions reacting with said cations to form water at said cathode;
(c) a cation exchange membrane interposed between said anode and said cathode, said membrane facilitating the migration of cations from said anode to said cathode and isolating said humidified fuel stream from said humidified oxidant stream;
and
(d) an electrical path for conducting electric current between said anode to said cathode, and
(e) means for maintaining the partial pressure of water vapor in said outlet fuel stream below the saturation pressure of water vapor contained therein;
(E) a water separator for removing water from said outlet fuel stream to produce a dehumidified fuel stream and a removed water stream;
(F) a reservoir for receiving said removed water stream from said water separator;
wherein at least one of said fuel humidification water supply and said oxidant humidification water supply is drawn from said reservoir, and whereby a substantial portion of water accumulated at said cathode is absorbed in said outlet fuel stream.

13 more elements

An electric power generation system comprising:

(A) a hydrogen-containing inlet fuel stream;
(B) an oxygen-containing inlet oxidant stream;
(C) an inlet coolant water stream;
(D) a fuel cell stack comprising:
(1) an electrochemically active section comprising at least one fuel cell, said fuel cell comprising:
(a) an anode having an inlet for directing said inlet fuel stream to the catalytically active portion of said anode, said anode producing cations from said inlet fuel stream and an outlet fuel stream;
(b) a cathode having an inlet for directing said inlet oxidant stream to the catalytically active portion of said cathode, said cathode producing anions from said inlet oxidant stream, said anions reacting with said cations to form water at said cathode;
(c) a cation exchange membrane interposed between said anode and said cathode, said membrane facilitating the migration of cations from said anode to said cathode and isolating said inlet fuel stream from said inlet oxidant stream;
and
(d) an electrical path for conducting electric current between said anode to said cathode, and
(e) means for maintaining the partial pressure of water vapor in said outlet fuel stream below the saturation pressure of water vapor contained therein;
(2) at least one coolant passage having an inlet for directing said inlet coolant water stream into thermal contact with said electrochemically active section to absorb heat generated within said active section and produce an outlet coolant water stream;
(E) a heat exchanger for removing heat from said outlet coolant water stream to produce a chilled coolant water stream;
(F) a water separator for removing water from said outlet fuel stream to produce a dehumidified fuel stream and a removed water stream;
(G) a reservoir for receiving said removed water stream from said water separator and said chilled coolant water stream from said heat exchanger;
wherein said inlet coolant water stream is drawn from said reservoir, and whereby a substantial portion of water accumulated at said cathode is absorbed in said outlet fuel stream.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/970,614Filed 3 Nov 1992 · continuation in part
Priority: 15 Jan 1991
Granted: 22 Nov 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

H01M 8/04156
With simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying: with product water removal
H01M 8/04029
Related to heat exchange: heat exchange using liquids
H01M 8/1007
Fuel cells with solid electrolytes: with both reactants being gaseous or vaporised
H01M 8/04097
Of gaseous reactants: with recycling of the reactants