Fuel cell-based generator system and method of the same

• US 5,885,727 A
• Filed: 05/23/1997
• Issued: 03/23/1999
• Est. Priority Date: 05/30/1996
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kawatsu, Shigeyuki
• Primary Examiner(s): Nuzzolillo, Maria
• Assistant Examiner(s): Wills, Monique M.
• Application Number:
  US08/862,257
• Time in Patent Office: 669 Days
• Field of Search: 429/20, 429/24, 429/26, 429/17
• US Class Current: 429/411
• CPC Class Codes: H01M 2300/0008 Phosphoric acid-based
• CPC Class Codes: H01M 4/926 on carbon or graphite
• CPC Class Codes: H01M 8/0258 characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• CPC Class Codes: H01M 8/0267 having heating or cooling means, e.g. heaters or coolant flow channels
• CPC Class Codes: H01M 8/04022 Heating by combustion
• CPC Class Codes: H01M 8/04029 Heat exchange using liquids
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04156 with product water removal
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04228 during shut-down
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/04303 applied during shut-down
• CPC Class Codes: H01M 8/0606 with means for production of gaseous reactants
• CPC Class Codes: H01M 8/0662 Treatment of gaseous reactants or gaseous residues, e.g. cleaning
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: H01M 8/2457 with both reactants being gaseous or vaporised
• CPC Class Codes: H01M 8/2483 characterised by internal manifolds
• CPC Class Codes: Y02E 60/36 Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

The present invention provides a fuel cell-based generator system that prevents a catalyst in fuel cells from being poisoned and a potential on oxygen electrodes of the fuel cells from lowering, while improving the energy efficiency. While I₂ is fed from a halogen tank 41 to a preliminary reaction tank 30 via a first conduit 33, H₂ O is fed from a water tank 43 to the preliminary reaction tank 30 via a second conduit 34. The preliminary reaction tank 30 is heated by the heat transmitted from a stack of fuel cells FC, and the reaction expressed as H₂ O+I₂ →2HI+(1/2)O₂ occurs in the preliminary reaction tank 30. HI produced by the above reaction is dissolved in excess H₂ O and fed into a reaction tank 50 via a fourth conduit 36. The reaction tank 50 is heated by the heat transmitted from the stack of fuel cells FC, and the reaction expressed as 2HI→H₂ +I2 occurs in the reaction tank 50. The gaseous mixture of H₂ and I₂ is flown into a hydrogen purifier 60 via a sixth conduit 54. The hydrogen purifier 60 separates gaseous hydrogen H₂ from the gaseous mixture. The gaseous hydrogen H₂ is then fed into flows paths of gaseous hydrogen in the stack of fuel cells FC.

Claims

1. A fuel cell-based generator system comprising:

gas producing means comprising heating means for generating heat; and

a reaction tank for reserving a halohydric acid and a catalyst for accelerating decomposition of the halohydric acid, said reaction tank producing the hydrogen-containing reaction gas by thermal decomposition that occurs with the heat from said heating means;

a fuel cell comprising a pair of electrodes with a catalyst carried thereon, to which a supply of the hydrogen-containing reaction gas is fed, said fuel cell generating an electromotive force through an electrochemical reaction of the reaction gas; and

a reaction gas supply conduit for feeding the reaction gas produced by said gas producing means to said fuel cell.

2. A fuel cell-based generator system in accordance with claim 1, said fuel-cell-based generator system further comprising:

heat transmission means for transmitting heat generated by said fuel cell to said heating means.

3. A fuel cell-based generator system in accordance with claim 2, wherein said fuel cell is driven at a temperature higher than temperature of the thermal decomposition occurring in said reaction tank,

said fuel cell-based generator system further comprising:

a cooling water flow path arranged around said fuel cell, cooling water being passed through said cooling water flow path,

said heat transmission means comprising circulation means connected to said cooling water flow path for circulating the cooling water between said cooling water flow path and said heating means.

4. A fuel cell-based generator system in accordance with claim 2, wherein said fuel cell is driven at a temperature lower than temperature of the thermal decomposition occurring in said reaction tank,

said heat transmission means comprising temperature increasing means for increasing temperature of the heat generated by said fuel cell to be higher than the temperature of the thermal decomposition.

5. A fuel cell-based generator system in accordance with claim 4, said fuel cell-based generator system further comprising a cooling water flow path arranged around said fuel cell, cooling water being passed through said cooling water flow path,

wherein said heat transmission means further comprising:

a first flow path connected to said cooling water flow path for making the cooling water passed to said heating means via said temperature increasing means when said fuel cell is in operation;

a second flow path bypassing said temperature increasing means for making the cooling water passed through said cooling water flow path to said heating means;

detection means for detecting that said fuel cell is at a stop; and

control means for, when said detection means detects that said fuel cell is at a stop, deactivating said first flow path and activating said second flow path.

6. A fuel cell-based generator system in accordance with claim 2, wherein said fuel cell is driven at a temperature lower than temperature of the thermal decomposition occurring in said reaction tank,

said fuel cell-based generator system further comprising:

a cooling water flow path arranged around said fuel cell, cooling water being passed through said cooling water flow path;

detection means for determining that said fuel cell is at a stop; and

feed means for, when said detection means detects that said fuel cell is at a stop, feeding the cooling water through said cooling water flow path to said heating means.

7. A fuel cell-based generator system in accordance with claim 6, said fuel cell-based generator system further comprising:

a reserve tank for reserving a material, from which the halohydric acid reserved in said reaction tank is produced; and

means for feeding the cooling water through said cooling water flow path to a periphery of said reserve tank at a time of stopping said fuel cell.

8. A fuel cell-based generator system in accordance with claim 1, said fuel cell-based generator system further comprising:

a reaction gas discharge path for enabling the reaction gas fed to said first electrode of said fuel cell to be discharged from said fuel cell; and

closing means for closing said reaction gas discharge path.

9. A fuel cell-based generator system in accordance with claim 1, said fuel cell-based generator system further comprising:

water recovery means for condensing water vapor evolved from said fuel cell by the electrochemical reaction to recover water; and

water feed means for feeding the water recovered by said water recovery means as a material for producing the halohydric acid.

10. A fuel cell-based generator system in accordance with claim 1, said fuel cell-based generator system further comprising:

a halogen tank for reserving a halogen;

a water tank for reserving water; and

feed means for feeding the halogen and water from said halogen tank and said water tank to said reaction tank,

wherein said heating means is arranged in the vicinity of said reaction tank,

said gas producing means further comprising;

hydrogen purification means for separating gaseous hydrogen from the hydrogen-containing reaction gas produced by said reaction tank.

11. A fuel cell-based generator system in accordance with claim 10, said fuel cell-based generator system further comprising means for transmitting heat generated by said fuel cell to said halogen tank.

12. A fuel cell-based generator system in accordance with claim 10, said fuel cell-based generator system further comprising means for transmitting heat generated by said fuel cell to said water tank.

13. A fuel cell-based generator system in accordance with claim 10, wherein said gas producing means further comprises oxygen purification means for separating oxygen from the reaction gas produced by said reaction tank,

said fuel cell-based generator system further comprising an oxygen supply conduit for feeding the oxygen separated by said oxygen purification means to one of said pair of electrodes of said fuel cell, said second electrode being different from said first electrode that receives a supply of the reaction gas.

14. A fuel cell-based generator system in accordance with claim 13, said fuel cell-based generator system further comprising:

a reaction gas discharge path connected to said fuel cell that receives a supply of the reaction gas from said gas producing means via said reaction gas supply conduit, a remaining portion of the reaction gas consumed by said fuel cell being discharged through said reaction gas discharge path;

an oxygen discharge path connected to said fuel cell that receives a supply of oxygen from said gas producing means via said oxygen supply conduit, a remaining portion of the oxygen consumed by said fuel cell being discharged through said oxygen discharge path;

a first valve member for regulating a gas flow passing through said reaction gas discharge path;

a second valve member for regulating a gas flow passing through said oxygen discharge path;

a first pressure sensor for measuring a gas pressure in said reaction gas discharge path;

a second pressure sensor for measuring a gas pressure in said oxygen discharge path; and

control means for regulating valve positions of said first valve member and said second valve member, in order to control the pressure difference between the gas pressure measured by said first pressure sensor and the gas pressure measured by said second pressure sensor to a predetermined value.

15. A fuel cell-based generator system in accordance with claim 10, wherein said hydrogen purification means comprises:

a filtration membrane for allowing selective permeation of hydrogen,

said fuel cell-based generator system further comprising;

a reaction gas discharge path connected to said fuel cell that receives a supply of the reaction gas from said gas producing means via said reaction gas supply conduit, a remaining portion of the reaction gas consumed by said fuel cell being discharged through said reaction gas discharge path;

regulating means for regulating a gas flow passing through said reaction gas discharge path;

pressure difference detection means for detecting a pressure difference before and after said filtration membrane; and

control means for controlling said regulating means, in order to keep the pressure difference detected by said pressure difference detection means within a predetermined range.

16. A fuel cell-based generator system in accordance with claim 13, said fuel cell-based generator system further comprising:

a reaction gas discharge path connected to said fuel cell that receives a supply of the reaction gas from said gas producing means via said reaction gas supply conduit, a remaining portion of the reaction gas consumed by said fuel cell being discharged through said reaction gas discharge path;

an oxygen discharge path connected to said fuel cell that receives a supply of oxygen from said gas producing means via said oxygen supply conduit, a remaining portion of the oxygen consumed by said fuel cell being discharged through said oxygen discharge path;

a first valve member for regulating a gas flow passing through said reaction gas discharge path;

a second valve member for regulating a gas flow passing through said oxygen discharge path;

a first sensor for measuring a gas flow in a flow path at an outlet of said hydrogen purification means;

a second sensor for measuring a gas flow in a flow path at an outlet of said oxygen purification means; and

control means for regulating valve positions of said first valve member and said second valve member, in order to enable a ratio of the gas flow measured by said first sensor to the gas flow measured by said second sensor to coincide with a ratio of hydrogen to oxygen consumed by said fuel cell.

17. A fuel cell-based generator system in accordance with claim 1, said fuel cell-based generator system further comprising:

a reaction gas discharge path connected to said fuel cell that receives a supply of the reaction gas from said gas producing means via said reaction gas supply conduit, a remaining portion of the reaction gas consumed by said fuel cell being discharged through said reaction gas discharge path,

wherein said heating means comprises means for combusting the reaction gas discharged through said reaction gas discharge path to generate heat.

18. A fuel cell-based generator system in accordance with claim 1, said fuel cell-based generator system further comprising:

reserve means for reserving the reaction gas produced by said gas producing means,

wherein said heating means comprises means for combusting the reaction gas reserved in said reserve means to generate heat.

19. A fuel cell-based generator system in accordance with claim 1, said fuel cell-based generator system further comprising:

reserve means for reserving the reaction gas produced by said gas producing means; and

starting-time reaction gas supply means for feeding the reaction gas reserved in said reserve means to said fuel cell through said reaction gas supply conduit at a time of starting operation of said fuel cell.

20. A fuel cell-based generator system in accordance with claim 1, said fuel cell-based generator system further comprising:

water producing means for producing water from a remaining portion of the reaction gas discharged from said fuel cell and an oxygen-containing gas supplied from outside; and

water feed means for feeding the water produced by said water producing means as a material for producing the halohydric acid.

21. A method of generating electricity with fuel cells, said method comprising the steps of:

(a) generating heat;

(b) reserving a halohydric acid produced by a reaction of a halogen with water as well as a catalyst for accelerating decomposition of the halohydric acid, and producing a gaseous mixture of hydrogen and another substance by thermal decomposition with the heat generated in said step (a); and

(c) feeding gaseous hydrogen included in said gaseous mixture as a reaction gas to an electrode with a catalyst carried thereon, and generating an electromotive force through an electrochemical reaction of the reaction gas.

22. A method in accordance with claim 21, wherein said step (b) is carried out by using heat generated by the electrochemical reaction in said step (c).