Solid oxide fuel cell system and method of controlling the same

Patent metadata

Field	Value
Publication number	US-2018375127-A1
Application number	US-201616064760-A
Country	US
Kind code	A1
Filing date	Dec 8, 2016
Priority date	Dec 25, 2015
Publication date	Dec 27, 2018
Grant date	—

Abstract

A solid oxide fuel cell system includes a solid oxide fuel cell, a combustor disposed in a cathode gas supply line of the fuel cell, a fuel supply unit configured to supply a fuel to the combustor, and a cathode gas supply unit configured to supply a cathode gas to the cathode gas supply line. The system further includes a stop control unit configured to perform a stop control of the fuel cell, which includes a control that sets a cathode gas supply amount from the cathode gas supply unit to a predetermined amount and a control that supplies the fuel from the fuel supply unit in a supply amount corresponding to the cathode gas supply amount.

First claim

1 .- 17 . (canceled)

18 . A solid oxide fuel cell system comprising:
a solid oxide fuel cell; a combustor disposed in a cathode gas supply line of the fuel cell; a fuel supply unit configured to supply a fuel to the combustor; a cathode gas supply unit configured to supply a cathode gas to the cathode gas supply line; and a stop control unit configured to perform a stop control, in response to stop of the fuel cell, including a control that sets a cathode gas supply amount from the cathode gas supply unit to a predetermined amount and a control that supplies the fuel from the fuel supply unit in a supply amount corresponding to the cathode gas supply amount.

19 . The solid oxide fuel cell system according to claim 18 , further comprising a voltage detection unit configured to detect a voltage of the fuel cell,
wherein the stop control unit performs the stop control when the voltage of the fuel cell is equal to or higher than a discharge request voltage.

20 . The solid oxide fuel cell system according to claim 19 , further comprising:
an air supply cut-off valve installed in the cathode gas supply line; and an exhaust cut-off valve installed in an exhaust line through which an exhaust gas from the fuel cell is discharged, wherein the stop control unit stops the fuel supply unit and the cathode gas supply unit, and closes the air supply cut-off valve and the exhaust cut-off valve, when the voltage of the fuel cell decreases to a predetermined target voltage lower than the discharge request voltage.

21 . The solid oxide fuel cell system according to claim 18 , further comprising a temperature detection unit configured to estimate or detect a temperature of the fuel cell,
wherein the stop control unit reduces the cathode gas supply amount and the fuel supply amount when the temperature of the fuel cell increases to or above a predetermined temperature.

22 . The solid oxide fuel cell system according to claim 21 , wherein the predetermined temperature is set to a heat-resisting temperature of the fuel cell.

23 . The solid oxide fuel cell system according to claim 18 , further comprising:
a temperature detection unit configured to estimate or detect a temperature of the fuel cell; and an ambient temperature detection unit configured to detect an ambient temperature of the fuel cell, wherein the stop control unit controls the fuel supply amount on the basis of a heat radiation amount of the fuel cell calculated from the temperature of the fuel cell and the ambient temperature.

24 . The solid oxide fuel cell system according to claim 18 , wherein the stop control unit maximizes the cathode gas supply amount from the cathode gas supply unit.

25 . The solid oxide fuel cell system according to claim 24 , further comprising a temperature detection unit configured to estimate or detect a temperature of the fuel cell,
wherein the stop control unit controls the fuel supply amount on the basis of an excess air factor λ 1 corresponding to the temperature of the fuel cell.

26 . The solid oxide fuel cell system according to claim 25 , wherein the excess air factor λ 1 is set such that an oxygen partial pressure of a combustion gas generated from the combustor and supplied to the fuel cell becomes equal to or higher than a lower limit partial pressure at which starvation of a cathode electrode of the fuel cell is avoidable.

27 . The solid oxide fuel cell system according to claim 26 , wherein the excess air factor λ 1 is set such that an oxygen partial pressure of a combustion gas generated from the combustor and supplied to the fuel cell becomes an oxygen partial pressure at which the voltage of the fuel cell is lower than a discharge request voltage.

28 . The solid oxide fuel cell system according to claim 18 , further comprising an air supply unit configured to supply a reformation air supplied to an anode of the fuel cell,
wherein the stop control unit maximizes a reformation air supply amount of the air supply unit.

29 . The solid oxide fuel cell system according to claim 28 , further comprising:
a reformation fuel supply unit configured to supply a reformation fuel to the anode of the fuel cell; and a temperature detection unit configured to estimate or detect a temperature of the fuel cell, wherein the stop control unit controls a reformation fuel supply amount on the basis of an excess air factor λ 2 corresponding to the temperature of the fuel cell.

30 . The solid oxide fuel cell system according to claim 29 , wherein the excess air factor λ 2 is set such that an oxygen partial pressure of the anode becomes equal to or lower than an upper limit of the oxygen partial pressure at which deterioration of the anode electrode of the fuel cell is avoidable.

31 . The solid oxide fuel cell system according to claim 28 , further comprising:
an air supply cut-off valve installed in the cathode gas supply line; and an exhaust cut-off valve installed in an exhaust line through which an exhaust gas from the fuel cell is discharged, wherein the stop control unit stops the fuel supply unit, the cathode gas supply unit and the air supply unit, and closes the air supply cut-off valve and the exhaust cut-off valve, when a voltage of the fuel cell reaches a target voltage lower than a discharge request voltage.

32 . A method of controlling a solid oxide fuel cell system, the method performing a stop control, in response to stop of a solid oxide fuel cell, including the steps of:
generating a combustion gas by supplying a fuel and a cathode gas to a combustor disposed in a cathode gas supply line of the fuel cell; and supplying the combustion gas to the fuel cell, wherein, in the generating the combustion gas, a cathode gas supply amount is set to a predetermined amount, and the fuel is supplied to the combustor in a supply amount corresponding to the cathode gas supply amount.

33 . The method according to claim 32 , wherein the stop control is performed when a voltage of the fuel cell is equal to or higher than a discharge request voltage.

34 . The method according to claim 33 , further comprising, when the voltage of the fuel cell decreases to a predetermined target voltage lower than the discharge request voltage, stopping the supply of the fuel and the cathode gas, and closing an air supply cut-off valve and an exhaust cut-off valve, the air supply cut-off valve being installed in the cathode gas supply line and the exhaust cut-off valve being installed in an exhaust line through which an exhaust gas from the fuel cell is discharged.

Assignees

• Nissan Motor

Inventors

• Yamazaki Tetsushi
• Yaguchi Tatsuya
• Shiomi Takeshi

Classifications

• H01M8/04365

  of other components of a fuel cell or fuel cell stacks · CPC title

• H01M8/04303

  applied during shut-down · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title

• H01M8/04559

  of fuel cell stacks · CPC title

• H01M8/04228 Primary

  during shut-down · CPC title