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US4474012A
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Steam turbine pressure rate limiter
Assignee: General Electric Co
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Filing: 1983-07-13
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Granted: 1984-10-02
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Expires: 2003-07-13
Abstract
Abstract A steam pressure rate limiter for a steam turbine system reduces the setting of a steam control valve when a rate of decrease in steam pressure is detected which exceeds a threshold value of rate of decrease. A floor on control of the steam control valve is enforced in order to maintain a predetermined amount of steam flow to the turbine thereby to provide for cooling of the turbine.
Inventors
- 👤 Harvey H. Chamberlain
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 05:07
CPC Classifications
F; F01; F01K; F01K13/00; F01K13/02
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
176 words
Apparatus for limiting a maximum rate of pressure decrease in a steam turbine system of the type having a boiler, a steam control valve and a turbine comprising: a digital integrator including a clock effective to produce a clock signal having a predetermined frequency, an up-down counter, and gating means, said gating means being effective to feed said predetermined frequency to said up-down counter in a first sense to produce one of counting up and counting down when said output of said integrator exceeds a signal related to said steam pressure and being further effective to feed said predetermined frequency to said up-down counter in a second sense to produce the other of counting up and counting down when said output of said integrator is less than said signal related to said steam pressure whereby a count is stored in said up-down counter; and means for reducing a setting of said steam control valve in proportion to an amount by which said count in said up-down counter differs from said signal related to said steam pressure.
Claim 2
Dependent Claim
176 words
Apparatus for limiting a maximum rate of pressure decrease in a steam turbine system of the type having a boiler, a steam control valve and a turbine comprising: a digital integrator including a clock effective to produce a clock signal having a predetermined frequency, an up-down counter, and gating means, said gating means being effective to feed said predetermined frequency to said up-down counter in a first sense to produce one of counting up and counting down when said output of said integrator exceeds a signal related to said steam pressure and being further effective to feed said predetermined frequency to said up-down counter in a second sense to produce the other of counting up and counting down when said output of said integrator is less than said signal related to said steam pressure whereby a count is stored in said up-down counter; and means for reducing a setting of said steam control valve in proportion to an amount by which said count in said up-down counter differs from said signal related to said steam pressure.
Claim 3
Dependent Claim
45 words
Apparatus for limiting a maximum rate of pressure decrease in a steam turbine system according to claim 1 wherein said predetermined clock frequency is effective to establish a maximum integration rate, said maximum integration rate being effective to establish said maximum rate of pressure decrease.
Claim 4
Dependent Claim
78 words
Apparatus for limiting a maximum rate of pressure decrease in a steam turbine system according to claim 2 wherein said gating means includes means for differencing an output of said integrator and a signal related to said steam pressure, an output of said means for differencing being substantially zero when said rate is less than a predetermined value and related to the amount by which said rate exceeds said predetermined rate when said rate exceeds said predetermined rate.
Claim 5
Dependent Claim
53 words
Apparatus for limiting a maximum rate of pressure decrease in a steam turbine system according to claim 3 wherein said means for reducing a setting includes means for preventing setting said steam control valve to a completely cutoff condition whereby at least a minimum flow of steam to said steam turbine is maintained.
Claim 6
Dependent Claim
60 words
Apparatus for limiting a maximum rate of pressure decrease in a steam turbine system according to claim 3 wherein said means for preventing includes means for generating a floor signal related to at least a desired minimum position of said steam control valve and means for limiting an output of said means for reducing in response to said floor signal.
Claim 7
Dependent Claim
40 words
Apparatus for limiting a maximum rate of pressure decrease in a steam turbine system according to claim 5 wherein said means for generating a floor signal is further responsive to a valve position command signal for producing said floor signal.
Claim 8
Dependent Claim
47 words
Apparatus for limiting a maximum rate of pressure decrease in a steam turbine system according to claim 1 wherein said means for reducing a setting includes means for differencing a valve position command signal and a signal from said digital integrator to produce a desired valve position.
Claim 9
Independent Claim
119 words
A method for limiting a maximum rate of pressure decrease in a steam turbine system of the type having a boiler, a steam control valve and a turbine comprising: counting pulses of a clock at a predetermined frequency in an up-down counter in a first direction when said pressure exceeds a count in said up-down counter and in a second direction when said pressure is less than said count; differencing said count and said pressure to produce a pressure rate signal, said predetermined frequency providing a threshold value of rate of steam pressure change which must exist to produce said pressure rate signal; and reducing a setting of said steam control valve in response to said pressure rate signal.
Claim 10
Independent Claim
119 words
A method for limiting a maximum rate of pressure decrease in a steam turbine system of the type having a boiler, a steam control valve and a turbine comprising: counting pulses of a clock at a predetermined frequency in an up-down counter in a first direction when said pressure exceeds a count in said up-down counter and in a second direction when said pressure is less than said count; differencing said count and said pressure to produce a pressure rate signal, said predetermined frequency providing a threshold value of rate of steam pressure change which must exist to produce said pressure rate signal; and reducing a setting of said steam control valve in response to said pressure rate signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-02 | 1988-04-02 | 1988-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-02 | 1992-04-02 | 1992-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-02 | 1996-04-02 | 1996-10-02 | $7700.00 | Window Closed / Lapsed |