System and method for regulating the speed of a steam turbine by controlling the turbine valve rack actuator

• US 5,295,783 A
• Filed: 04/19/1993
• Issued: 03/22/1994
• Est. Priority Date: 04/19/1993
• Status: Expired due to Term

• Current Assignee: Delaware Capital Formation Incorporated (Dover Corporation)
• Original Assignee: Conmec, Inc.
• Inventors: Parker, Charles A., Lesko, Frederick H.
• Primary Examiner(s): KWON, JOHN
• Application Number:
  US08/049,797
• Time in Patent Office: 337 Days
• Field of Search: 415/30, 415/36, 415/39, 415/40, 415/41, 415/42, 415/43, 415/1, 60/413
• US Class Current: 415/30
• CPC Class Codes: F01D 17/06 responsive to speed
• CPC Class Codes: F01D 17/26 fluid, e.g. hydraulic

Abstract

A system and method for regulating the speed of a steam turbine by operating a steam valve rack assembly to adjust the flow of steam to the turbine by controlling the position of the turbine valve rack actuator in response to high pressure oil fed, reacting to signals from a speed control system, through a proportional valve to the valve rack actuator. High pressure oil is fed to the proportional valve from a hydraulic oil accumulator, charged with an inert gas, in which high pressure oil is stored. A source of low pressure oil directed to a pressure intensifying device increases the oil pressure to a high pressure and circulates the high pressure oil to the hydraulic oil accumulator and the proportional valve to stroke the turbine valve rack actuator in response to signals from the speed control system. The system further includes an emergency stop valve system which operates to close the turbine valve rack assembly very rapidly in the event of a serious turbine condition.

Claims

1. A system for regulating the speed of a turbine by operating a steam valve rack assembly to adjust the flow of steam to the turbine by controlling the position of the turbine valve rack actuator in response to oil within a first pressure range fed, reacting to signals from a closed loop speed control system, through a proportional valve to the turbine valve rack actuator comprising:

(A) a source of oil within a second pressure range lower than said first pressure range;

(B) oil accumulator; and

(C) pressure intensifying means arranged to receive oil within the second pressure range from the oil source, increase the pressure thereof to within said first pressure range, and circulate the oil within the first pressure range to the oil accumulator and proportional valve;

whereby oil within said first pressure range released from the accumulator passes to and through the proportional valve to the valve rack actuator to close the valve rack assembly and reduce the flow of steam to said turbine when a signal from the closed loop speed control system calls for a reduction in the speed of said turbine and to open the valve rack assembly and increase the flow of steam to the turbine when a signal from the closed loop speed control system calls for an increase in the speed of the turbine.

2. The invention of claim 1 wherein oil within the first pressure range is between 600 psig and 2000 psig and oil within the second pressure range is between 20 psig and 200 psig.

3. The invention of claim 1 wherein the oil accumulator has a capacity of between 5 and 40 gallons and is pressurized by an inert gas.

4. The invention of claim 3 wherein the inert gas in the oil accumulator is pressurized to between 600 psig and 1400 psig.

5. The invention of claim 1 wherein the pressure intensifying means comprises:

(A) a hydraulic motor; and

(B) a hydraulic pump.

6. The invention of claim 5 wherein the pressure intensifying means hydraulic pump has a capacity of between 0.1 gallons per minute and 3.0 gallons per minute.

7. The invention of claim 5 wherein the pressure intensifying means hydraulic motor has an output capability about equal to the input torque requirements of the hydraulic pump such that the hydraulic motor stalls when the accumulator is fully charged.

8. The invention of claim 1 wherein a velocity fuse is positioned between the source of oil and the pressure intensifying means.

9. The invention of claim 8 wherein the velocity fuse flow rate does not exceed 20 gallons per minute.

10. A system for regulating the speed of a turbine by operating the steam valve rack assembly to adjust the flow of steam to the turbine by controlling the position of the turbine valve rack actuator in response to oil within a first pressure range fed, reacting to signals from a closed loop speed control system, through a proportional valve to the valve rack actuator, comprising:

(A) a source of oil within a second pressure range lower than the first pressure range;

(B) an oil accumulator; and

(C) pressure intensifying means arranged to receive oil within the second pressure range from the source, increase the pressure thereof to within the first pressure range, and circulate the oil within the first pressure range to the oil accumulator and the proportional valve;

(D) emergency stop valve system comprising

(1) a first emergency stop valve;

(2) a second emergency stop valve; and

(3) an emergency solenoid valve;

whereby in response to an external signal the emergency solenoid valve operates to dump oil within the first pressure range from the first and second emergency stop valves to an oil drain permitting the first and second emergency stop valves to open and allow oil within the first pressure range from the oil accumulator to flow through the first emergency stop valve to the first side of the turbine valve rack actuator and oil within the first pressure range to drain from the second side of the turbine valve rack actuator through the second emergency stop valve closing the turbine valve rack actuator and the steam valve rack assembly cutting off the supply of steam to the turbine.

11. The system of claim 10 wherein the pressure intensifying means comprises:

(A) a hydraulic motor; and

(B) a hydraulic pump.

12. A method for regulating the speed of a turbine by operating a steam valve rack assembly to adjust the flow of steam to the turbine by controlling the position of the turbine valve rack actuator in response to oil within a first pressure range fed, reacting to signals from a closed loop speed control system, through a proportional valve to the the turbine valve rack actuator, comprising the steps of:

(A) utilizing oil within a second pressure range from a source thereof to operate pressure intensifying means to increase the pressure thereof within the first pressure range;

(B) circulating oil within the first pressure range to the proportional valve and to an oil accumulator containing inert gas within a third pressure range;

(C) continuing the circulation of oil within the first pressure range to the oil accumulator for storage therein whereby the pressure of the inert gas therein is equalized to within the first pressure range;

(D) releasing and transferring on demand at least a portion of the oil stored in the oil accumulator within the first pressure range to the proportional valve and to the turbine valve rack actuator to adjust the position thereof to control the flow of steam to the turbine when a signal from the closed loop speed control system calls for a reduction in the speed of the turbine and to open the turbine valve rack assembly and increase the flow of steam to the turbine when a signal from the closed loop speed control system calls for an increase in the speed of the turbine.

13. The method of claim 12 wherein oil within the first pressure range is between 600 psig and 2000 psig and oil within the second pressure range is between 20 psig and 200 psig.

14. The method of claim 12 wherein the pressure intensifying means comprises:

(A) a hydraulic motor; and

(B) a hydraulic pump.

15. The method of claim 14 wherein the pressure intensifying means hydraulic pump has a capacity of between 0.1 gallons per minute and 3.0 gallons per minute.

16. The invention of claim 14 wherein a velocity fuse is positioned between the source of oil and the pressure intensifying means.

17. The invention of claim 16 wherein the velocity fuse flow rate does not exceed 20 gallons per minute.

18. The method of claim 12 wherein inert gas is first stored in the accumulator at a third pressure between 600 psig and 1400 psig.

19. The method of claim 12 wherein the oil accumulator has a capacity of between 5 and 40 gallons and is pressurized by an inert gas.

20. The method of claim 12 wherein the inert gas in the oil accumulator is first pressurized to between 600 psig and 1400 psi.