METHOD AND SYSTEM FOR CONTROLLING AN EXHAUST GAS RECIRCULATION SYSTEM

• US 20090145126A1
• Filed: 12/10/2007
• Published: 06/11/2009
• Est. Priority Date: 12/10/2007
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Maly, Peter Martin, Taylor, Robert W., Chillar, Rahul J., Fuller, Jason D.
• Granted Patent: US 8,046,986 B2
• Time in Patent Office: Days
• US Class Current: 60/605.200
• CPC Class Codes: F01D 25/30 Exhaust heads, chambers, or the like
• CPC Class Codes: F02C 3/34 with recycling of part of the working fluid, i.e. semi-closed cycles with combustion products in the closed part of the cycle
• CPC Class Codes: F02C 6/16 for storing compressed air
• CPC Class Codes: F05D 2220/74 a gas turbine
• CPC Class Codes: F05D 2270/08 to produce clean exhaust gases
• CPC Class Codes: F05D 2270/0831 indirectly, at the exhaust
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
• CPC Class Codes: Y02E 60/16 Mechanical energy storage, e.g. flywheels or pressurised fluids

Abstract

A method and system for controlling an exhaust gas recirculation (EGR) system is provided. The method and system may incorporate a device or devices that continuously monitors an exhaust stream for harmful constituents. The method and system may control components of the EGR system based on the concentration of harmful constituents within the exhaust.

Claims

1. A method of reducing constituents within an exhaust stream, wherein the exhaust stream is generated by a turbomachine;

the method comprising;

providing at least one exhaust gas recirculation (EGR) system comprising;

at least one EGR flow conditioning device, a constituent reduction system, at least one flow control device;

wherein the EGR system reduces constituents within the exhaust stream from a first concentration to a second concentration and recirculates the exhaust stream to an inlet section of the turbomachine;

modulating the at least one flow control device;

utilizing the constituent reduction system to reduce the constituents within the exhaust stream;

determining whether constituents within the exhaust stream are within a constituent range; and

if constituents are within the constituent range, then modulating the at least one flow control device to allow for the exhaust stream to enter the inlet section.

2. The method of claim 1, wherein the constituents comprise at least one of:

SOx, NOx, CO₂, water, chloride ions, acids, aldehydes, hydrocarbons, or combinations thereof.

3. The method of claim 1, further comprising determining whether at least one initialization permissive is satisfied.

4. The method of claim 3, wherein the at least one initialization permissive comprises at least one of:

preheating status of the EGR system;

operational readiness of the EGR system components;

status of at least one fault condition of the EGR system; and

combinations thereof.

5. The method of claim 1, further comprising determining whether at least one operational permissive is satisfied.

6. The method of claim 5, wherein the at least one operational permissive comprises at least one of:

an EGR fraction;

a concentration range of at least one constituent;

the constituent reduction system is operating within an operational range;

a status of at least one fault condition of the EGR system;

a combustion dynamics margin;

a compressor stall margin; and

combinations thereof.

7. The method of claim 1, wherein the method allows for aborting the operation of the EGR system.

8. The method of claim 1, wherein the step of utilizing the constituent reduction system to reduce the constituents further comprises reducing the temperature of the exhaust stream to a range from about 35 degrees Fahrenheit to about 100 degrees Fahrenheit.

9. The method of claim 1, wherein the step of utilizing the constituent reduction system to reduce the constituents further comprises removing up to about 90 percent of SOx constituents within the exhaust stream.

10. The method of claim 9, further comprising receiving a measurement of a SOx concentration within the exhaust stream, wherein the measurement is used to adjust the operation of the constituent reduction system.

11. The method of claim 9, further comprising receiving a pH range of a cooling fluid used with the constituent reduction system, wherein the pH range is used to determine the SOx concentration within the exhaust stream;

and wherein the pH range is used to adjust the operation of the constituent reduction system.

12. The method of claim 1, wherein the step of modulating the at least one flow control device to an open position allowing for diverting up to about 35 percent of the total exhaust flow to the exhaust stream.

13. The method of claim 1, wherein the constituent reduction system comprises at least one of:

a heat exchanger, a scrubber, a de-mister, a reagent injector, a spray tower, an absorber vessel, an evaporative gas conditioning tower, a wet electrostatic precipitator;

mixing station, or combinations thereof.

14. The method of claim 1, wherein the step of utilizing the constituent reduction system comprises utilizing at least one constituent feedback device;

wherein the at least one constituent feedback device provides data on the at least one constituent within the exhaust stream.

15. The method of claim 1, wherein the step of utilizing the constituent reduction system further comprises determining an injection rate of a fluid utilized in the constituent reduction system, wherein the injection rate is determined by a concentration of constituents within the exhaust stream.

16. A system for reducing constituents within an exhaust stream, wherein the exhaust stream is generated by a turbomachine;

the system comprising;

at least one exhaust gas recirculation (EGR) system comprising;

at least one EGR flow conditioning device, a constituent reduction system, at least one flow control device;

wherein the EGR system reduces constituents within the exhaust stream from a first concentration to a second concentration and recirculates the exhaust stream to an inlet section of the turbomachine;

wherein the constituents comprise at least one of;

SOx, NOx. CO₂, water, chloride ions, acids, aldehydes, hydrocarbons, or combinations thereof; and

a control system, wherein the control system;

determines whether at least one initialization permissive is met;

modulates the at least one flow control device;

utilizes the EGR flow conditioning device;

utilizes the constituent reduction system;

determines whether constituents within the exhaust stream are within a constituent range;

if constituents are within the constituent range, then the control system modulates the at least one flow control device; and

determines whether at least one operational permissive is met.

17. The system of claim 16, wherein the constituent reduction system reduces up to about 90 percent of SOx constituents within the exhaust stream;

and wherein a direct measurement of a SOx concentration is used to adjust the operation of the constituent reduction system.

18. The system of claim 16, wherein the constituent reduction system comprises at least one constituent feedback device;

wherein the at least one constituent feedback device provides data on at least one constituent within the exhaust stream.

19. The system of claim 16, wherein the constituent reduction system determines an injection rate of a fluid utilized in the constituent reduction system, wherein the injection rate is determined by a concentration of at least one constituent within the exliaust stream.

20. The system of claim 16, wherein the control system receives a measurement of a SOx concentration within the exhaust stream and uses the measurement to adjust the operation of the constituent reduction system.

21. The method of claim 20, wherein the control system receives a pH range of a cooling fluid used with the constituent reduction system, wherein the pH range is used to determine the SOx concentration within the exhaust stream;

and the control system uses the pH range to adjust the operation of the constituent reduction system.