Active draft control for combined cycle power plant shutdown

Patent metadata

Field	Value
Publication number	US-2018347407-A1
Application number	US-201715611832-A
Country	US
Kind code	A1
Filing date	Jun 2, 2017
Priority date	Jun 2, 2017
Publication date	Dec 6, 2018
Grant date	—

Abstract

A system and method for active draft control through a combined cycle power plant (CCPP) can initiate a CCPP shutdown, activate the recirculated exhaust gas (REG) system for the turbomachine; measure a HRSG airflow through the HRSG; communicate the HRSG airflow to a controller configured to condition a control signal; and adjust a recirculated exhaust gas volume in accordance with the control signal.

First claim

What is claimed is:

1 . A method for active draft control through a combined cycle power plant (CCPP), comprising the steps of:
initiating a CCPP shutdown, the CCPP comprising a turbomachine and a heat recovery steam generator (HRSG); measuring an HRSG airflow through the HRSG; communicating the HRSG airflow to a controller configured to condition a control signal; and adjusting a recirculated exhaust gas volume through a REG system in accordance with the control signal.

2 . The method of claim 1 , wherein the recirculated exhaust gas (REG) system further comprises a minimum purge airflow.

3 . The method of claim 1 , wherein the HRSG airflow is measured by a differential pressure gage, hot-wire anemometer, and combinations thereof.

4 . The method of claim 1 , wherein the recirculated exhaust gas (REG) system further comprises a bypass fan.

5 . The method of claim 4 , further comprising the steps of:
establishing a control setpoint for at least one of the differential pressure gage, the hot-wire anemometer, and combinations thereof; energizing the bypass fan; and adjusting the speed of the bypass fan to control the recirculated exhaust gas volume in accordance with the control signal.

6 . The method of claim 5 , wherein the control setpoint for the differential pressure gage is in the range of 0 to 0.01 psig.

7 . The method of claim 4 , wherein the recirculated exhaust gas (REG) system further comprises at least one control damper.

8 . The method of claim 7 , further comprising the steps of:
establishing a control setpoint for at least one of the differential pressure gage, the hot-wire anemometer, and combinations thereof; energizing the bypass fan; and adjusting the position of the at least one control damper to control the recirculated exhaust gas volume in accordance with the control signal.

9 . The method of claim 8 , wherein the control setpoint for the differential pressure gage is in the range of 0 to 0.01 psig.

10 . The method of claim 1 , further comprising the step of:
supplying the recirculated exhaust gas volume to an inlet section, at least one turbomachine casing opening, an ambient REG exhaust, and combinations thereof.

11 . The method of claim 2 , wherein the recirculated exhaust gas (REG) system further communicates with a CCPP internal control system configured to adjust a control setpoint for the recirculated exhaust gas volume above the minimum purge airflow.

12 . A system for actively controlling draft through a combined cycle power plant (CCPP), comprising:
a turbomachine, a heat recovery steam generator (HRSG) comprising a HRSG exhaust stack, a bypass exhaust stack, and a recirculated exhaust gas (REG) system configured to;
activate when a CCPP shutdown is initiated,
measure an HRSG airflow through the HRSG;
communicate the HRSG airflow to a controller configured to condition a control signal; and
adjust a recirculated exhaust gas volume through a REG system in accordance with the control signal.

13 . The system of claim 12 , wherein the recirculated exhaust gas (REG) system further comprises a minimum purge airflow.

14 . The system of claim 12 , wherein the HRSG airflow is measured by a differential pressure gage, hot-wire anemometer, and combinations thereof.

15 . The system of claim 12 , wherein the recirculated exhaust gas (REG) system further comprises a bypass fan.

16 . The system of claim 15 , wherein the REG system is further configured to:
establish a control setpoint for at least one of the differential pressure gage, the hot-wire anemometer, and combinations thereof; energize the bypass fan; and adjust the speed of the bypass fan to control the recirculated exhaust gas volume in accordance with the control signal.

17 . The system of claim 16 , wherein the control setpoint for the differential pressure gage is in the range of 0 to 0.01 psig.

18 . The system of claim 15 , wherein the recirculated exhaust gas (REG) system further comprises at least one control damper.

19 . The system of claim 16 , wherein the REG system is further configured to:
establish a control setpoint for at least one of the differential pressure gage, the hot-wire anemometer, and combinations thereof; energize the bypass fan; and adjust the position of the at least one control damper in accordance with the control signal.

20 . The system of claim 12 , wherein the REG system is further configured to:
supply the recirculated exhaust gas volume to an inlet section, at least one turbomachine casing opening, an ambient REG exhaust, and combinations thereof.

Assignees

• Gen Electric

Inventors

• Mohr Wolfgang Franz Dietrich
• Rechsteiner Kurt
• Johnson David Martin
• Black Kenneth Damon

Classifications

• F01K23/06

  combustion heat from one cycle heating the fluid in another cycle · CPC title

• F01K13/02 Primary

  Controlling, e.g. stopping or starting · CPC title

• F01K13/003

  Arrangements for measuring or testing (in general G01) · CPC title

• F01K23/00

  Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids · CPC title

• F01D11/20

  Actively adjusting tip-clearance · CPC title