Power generation system, and methods for starting and operating fuel cell in power generation system

Patent metadata

Field	Value
Publication number	US-9806358-B2
Application number	US-201314438235-A
Country	US
Kind code	B2
Filing date	Oct 28, 2013
Priority date	Oct 31, 2012
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

The present invention enables a fuel cell to be stably started by minimizing a lack of air in a gas turbine when starting the fuel cell. This fuel cell system comprises: a gas turbine ( 11 ) having a compressor ( 21 ) and a combustor ( 22 ); a first compressed air supply line ( 26 ) that supplies compressed air (A 1 ), which has been compressed by the compressor, to the combustor; a solid oxide fuel cell (SOFC) ( 13 ) having an air electrode and a fuel electrode; a second compressed air supply line ( 31 ) that supplies partially compressed air (A 2 ), which has been compressed by the compressor, to the air electrode; a blower ( 33 ) that is disposed on the second compressed air supply line, and raises the pressure of the compressed air (A 2 ); a circulation booster line ( 60 ) connecting the upstream side and downstream side of the blower in the second compressed air supply line; a control valve ( 61 ) disposed on the circulation booster line; a control valve ( 63 ) disposed between the circulation booster line in the second compressed air supply line and the SOFC; and a control device ( 62 ) that closes the control valves and opens the control valves to start the blower when starting the SOFC.

First claim

The invention claimed is:

1. A power generation power generation system comprising:
a gas turbine having a compressor and a combustor;
a first compressed air supply line supplying compressed air compressed by the compressor to the combustor;
a fuel cell having an air electrode and a fuel electrode;
a second compressed air supply line supplying a portion of the compressed air compressed by the compressor to the air electrode;
a booster provided in the second compressed air supply line, the booster boosting pressure of the compressed air;
a booster circulation line connected to an upstream side and to a downstream side of the booster in the second compressed air supply line;
a first control valve provided in the booster circulation line;
a second control valve provided between the booster circulation line and the fuel cell, in the second compressed air supply line; and
a controller, during starting of the fuel cell, closing the second control valve while opening the first control valve and activating the booster.

2. The power generation system according to claim 1 , further comprising a detector detecting at least one of a pressure and a flow rate of compressed air in the booster, wherein
the controller opens the second control valve while closing the first control valve upon at least one of the pressure and the flow rate detected by the detector reaching a predetermined value.

3. A method for starting a fuel cell in a power generation system, comprising the steps of:
upon the starting of the fuel cell, activating a booster provided before an air electrode of the fuel cell to boost a pressure of a portion of compressed air compressed by a compressor of a gas turbine as well as to circulate the portion of the compressed air from a downstream side to an upstream side of the booster; and
upon at least one of the pressure and a flow rate of the portion of the compressed air compressed by the compressor of the gas turbine reaching a predetermined value, supplying the portion of the compressed air to the air electrode of the fuel cell while boosting the pressure of the portion of the compressed air with the booster, wherein
the boosting of the pressure is performed while stopping supplying the portion of the compressed air to the fuel cell.

4. A power generation system comprising:
a gas turbine having a compressor, a combustor and a turbine;
a first compressed air supply line supplying a portion of compressed air compressed by the compressor to the combustor;
a fuel cell having an air electrode and a fuel electrode;
a second compressed air supply line supplying an other portion of the compressed air compressed by the compressor to the air electrode; a booster provided in the second compressed air supply line;
a pressure control valve provided in the second compressed air supply line;
a first detector provided on an upstream side of the pressure control valve in the second compressed air supply line, the first detector detecting a first pressure of the other portion of the compressed air supplied to the air electrode;
a second detector provided on a downstream side of the pressure control valve in the second compressed air supply line, the second detector detecting a second pressure of the other portion of the compressed air supplied to the air electrode;
a controller controlling an extent of opening of the pressure control valve in response to a fluctuation in the first pressure detected by the first detector and a fluctuation in the second pressure detected by the second detector,
such that a pressure of the other portion of the compressed air supplied to the air electrode is held constant, in a state where the portion of the compressed air compressed by the compressor is supplied to the combustor via the first compressed air supply line and the turbine starts rotating, and where the other portion of the compressed air is supplied to the air electrode via the second compressed air supply line.

5. The power generation system according to claim 4 , wherein the pressure control valve is constituted by a plurality of control valves being arranged in parallel.

6. A method for operating a fuel cell in a power generation system, comprising the steps of:
supplying a portion of a compressed air compressed by a gas turbine to a combustor of the gas turbine;
supplying an other portion of the compressed air compressed by a compressor of the gas turbine to an air electrode of a fuel cell via a pressure control valve; providing a booster in association with the other portion of the compressed air; and
upon (i) a first pressure, on an upstream side of the pressure control valve, of the other portion of the compressed air supplied to the fuel cell fluctuating, and (ii) a second pressure, on a downstream side of the pressure control valve, of the other portion of the compressed air fluctuating, adjusting a flow rate of the other portion of the compressed air such that a pressure of the other portion of the compressed air is held constant.

7. The power generation system according to claim 1 ,
wherein the second control valve is arranged between the fuel cell and a downstream connection where the second compressed air supply line connects to the booster circulation line.

8. A power generation system according to claim 4 ,
wherein
both the first detector and the second detector are provided in an upstream side of the booster.

Assignees

• Mitsubishi Hitachi Power Sys

Inventors

• Nakamoto Yukimasa
• Fujita Kazunori

Classifications

• Y02E60/50

  Fuel cells · CPC title

• H01M8/04111 Primary

  using a compressor turbine assembly · CPC title

• H01M8/0662 Primary

  Treatment of gaseous reactants or gaseous residues, e.g. cleaning · CPC title

• H01M8/04395

  of cathode reactants at the inlet or inside the fuel cell · CPC title

• H01M2008/1293

  Fuel cells with solid oxide electrolytes · CPC title