US4912732A
Expired / Lapsed
US
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Automatic steam generator control at low power
Assignee: Combustion Engineering Inc
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Filing: 1988-04-14
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Granted: 1990-03-27
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Expires: 2008-04-14
Abstract
Abstract The steam generator water level, the feed water temperature, and the reactor power are continuously measured and a level signal (76), a temperature signal (78), and a power signal (80) commensurate with these measurements are respectively generated. From the power signal and the temperature signal, a target flow signal (84) is generated corresponding to the feedwater flow rate that would produce a stable steam generator water level at the steady state condition of the power signal and the temperature signal. The level signal is compared to a level signal setpoint (54) and a resulting level error signal (86) is generated. The level error signal is adjusted by a gain factor (88) that is dependent on the temperature signal to produce an adjusted level error signal (90). The feedwater flow through the bypass valve is then controlled in response to the target flow signal (84') and the adjusted level error signal. In a preferred implementation of the invention, the transition between low power control using the bypass valve and high power control using the main feed water valve is accomplished by generating a main valve position signal (118), and generating an enable signal (124) when the power signal is within a desired transition power range. When the power is in the transition range, the feedwater flow through the bypass valve is ramped down or up in response to the target flow signal, the adjusted level error signal, and the main valve position signal, as the main feedwater flow increases or decreases.
Inventors
- 👤 Gurdip Singh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:00
CPC Classifications
F; F22; F22B; F22B35/00; F22B35/004; G; G21; G21D; G21D3/00; G21D3/08; G21D3/10; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
220 words
In a pressurized water nuclear reactor steam supply system having a circulating steam generator including a feedwater pump, a main feedwater valve and a bypass feedwater valve having a lower flow capacity than that of the mainfeed water valve, a method for controlling the water level in the steam generator during operation in a low power regime spanning the range of about 0 to 15% of full power and excluding controlling water level during refilling of the steam generator immediately following a reactor trip, comprising the steps of: generating a level signal commensurate with the water level in the steam generator; generating a temperature signal commensurate with the feedwater temperature; generating a power signal commensurate with the reactor power; from the power signal and the temperature signal, forming a target flow signal corresponding to the feedwater flow rate that would produce a stable steam generator water level for a steady state condition of said power signal and said temperature signal; comparing the level signal to a level signal setpoint and generating a level error signal; adjusting the level error signal by a gain factor that is dependent on the temperature signal, to produce an adjusted level error signal; and controlling the feedwater flow through the bypass valve in response to the target flow signal and the adjusted level error signal.
Claim 2
Dependent Claim
220 words
In a pressurized water nuclear reactor steam supply system having a circulating steam generator including a feedwater pump, a main feedwater valve and a bypass feedwater valve having a lower flow capacity than that of the mainfeed water valve, a method for controlling the water level in the steam generator during operation in a low power regime spanning the range of about 0 to 15% of full power and excluding controlling water level during refilling of the steam generator immediately following a reactor trip, comprising the steps of: generating a level signal commensurate with the water level in the steam generator; generating a temperature signal commensurate with the feedwater temperature; generating a power signal commensurate with the reactor power; from the power signal and the temperature signal, forming a target flow signal corresponding to the feedwater flow rate that would produce a stable steam generator water level for a steady state condition of said power signal and said temperature signal; comparing the level signal to a level signal setpoint and generating a level error signal; adjusting the level error signal by a gain factor that is dependent on the temperature signal, to produce an adjusted level error signal; and controlling the feedwater flow through the bypass valve in response to the target flow signal and the adjusted level error signal.
Claim 3
Dependent Claim
33 words
The method of claim 1 further including the step of limiting the target flow signal to a value corresponding to reactor power operation within twice the range of the low power operating regime.
Claim 4
Dependent Claim
38 words
The method of claim 1 wherein the step of adjusting the level error signal is preceded by the step of limiting the level error signal to a value corresponding to acceptable operation within the low power operating regime.
Claim 5
Dependent Claim
23 words
The method of claim 1 wherein the step of measuring the reactor power includes the step of measuring the nuclear reactor neutron flux.
Claim 6
Dependent Claim
24 words
The method of claim 1 wherein the step of adjusting the level error signal includes increasing the gain factor as the feedwater temperature increases.
Claim 7
Dependent Claim
88 words
The method of claim 1 further including the steps of: generating a main valve position signal indicative of the position of the main feedwater valve; generating an enable signal when the power signal is within a transition range that includes a portion of the low power regime and a portion of the higher power regime; and when the enable signal is generated, controlling the feedwater flow through the bypass valve in response to the target flow signal, the adjusted level error signal, and the main valve position signal.
Claim 8
Dependent Claim
30 words
The method of claim 2 wherein the step of limiting the target flow signal limits the signal to a value within the range of about 0-20% of the reactor power.
Claim 9
Dependent Claim
44 words
The method of claim 2 further including the step of passing the target flow signal through a first adaptive network after the step of limiting the target flow signal, the LaPlace transform co-efficients in said first adaptive network being functions of said power signal.
Claim 10
Dependent Claim
56 words
The method of claim 3 further including the step of passing the level signal through a second adaptive network and passing the level error signal through a third adaptive network, before the step of adjusting the error signal, wherein the LaPlace transform co-efficients in the second and third adaptive networks are functions of the level signal.
Claim 11
Dependent Claim
33 words
The method of claim 3 further including the step of limiting the target flow signal to a value corresponding to reactor power operation within twice the range of the low power operating regime.
Claim 12
Dependent Claim
28 words
The method of claim 6 wherein at a predetermined power level above the lower power regime, the step of controlling the feedwater flow includes closing the bypass valve.
Claim 13
Dependent Claim
44 words
The method of claim 10 further including the step of passing the target flow signal through a first adaptive network after the step of limiting the target flow signal, the LaPlace transform co-efficients in said first adaptive network being functions of the power signal.
Claim 14
Dependent Claim
56 words
The method of claim 12 further including the step of passing the level signal through a second adaptive network and passing the level error signal through a third adaptive network, before the step of adjusting the error signal, wherein the LaPlace transform co-efficients in the second and third adaptive networks are functions of the level signal.
Claim 15
Dependent Claim
24 words
The method of claim 10 wherein the step of adjusting the level error signal includes increasing the gain factor as the feedwater temperature increases.
Claim 16
Dependent Claim
30 words
The method of claim 14 wherein the step of limiting the target flow signal limits the signal to a value within the range of about 0-20 of the reactor power.
Claim 17
Dependent Claim
88 words
The method of claim 10 further including the steps of: generating a main valve position signal indicative of the position of the main feedwater valve; generating an enable signal when the power signal is within a transition range that includes a portion of the low power regime and a portion of the higher power regime; and when the enable signal is generated, controlling the feedwater flow through the bypass valve in response to the target flow signal, the adjusted level error signal, and the main valve position signal.
Claim 18
Dependent Claim
28 words
The method of claim 16 wherein at a predetermined power level above the lower power regime, the step of controlling the feedwater flow includes closing the bypass valve.
Claim 19
Dependent Claim
177 words
In a pressurized water nuclear reactor steam supply system having a circulating steam generator including a feedwater pump, a main feedwater valve and a bypass feedwater valve having a lower flow capacity than that of the main feedwater valve, a method for controlling the water level in the steam generator during operation in a low power regime spanning the range of about 0 to 15% of full power and excluding controlling water level during refilling of the steam generator immediately following a reactor trip, comprising the steps of: generating a level signal commensurate with water level in the steam generator; generating a temperature signal commensurate with the feedwater temperature; generating a power signal commensurate with the reactor power; comparing the level signal to a level signal setpoint and generating a level error signal; adjusting the level error signal by a gain factor that is dependent on the temperature signal, to produce an adjusted level error signal; and controlling the feedwater flow through the bypass valve in response to the power signal and the adjusted level error signal.
Claim 20
Dependent Claim
177 words
In a pressurized water nuclear reactor steam supply system having a circulating steam generator including a feedwater pump, a main feedwater valve and a bypass feedwater valve having a lower flow capacity than that of the main feedwater valve, a method for controlling the water level in the steam generator during operation in a low power regime spanning the range of about 0 to 15% of full power and excluding controlling water level during refilling of the steam generator immediately following a reactor trip, comprising the steps of: generating a level signal commensurate with water level in the steam generator; generating a temperature signal commensurate with the feedwater temperature; generating a power signal commensurate with the reactor power; comparing the level signal to a level signal setpoint and generating a level error signal; adjusting the level error signal by a gain factor that is dependent on the temperature signal, to produce an adjusted level error signal; and controlling the feedwater flow through the bypass valve in response to the power signal and the adjusted level error signal.
Claim 21
Dependent Claim
32 words
The method of claim 18 further including the step of limiting the power signal to a value corresponding to reactor power operation within twice the range of the low power operating regime.
Claim 22
Dependent Claim
29 words
The method of claim 19 wherein the step of limiting the power signal limits the signal to a value within the range of about 0-20% of the reactor power.
Claim 23
Dependent Claim
69 words
The method of claim 18 further including the step of forming a target flow signal from the power signal, the target flow signal being commensurate with the long term feedwater flow rate requirements corresponding to a steady state condition of the measured reactor power, and wherein the step of controlling the feedwater flow includes controlling the flow in response to the target signal and the adjusted level error signal.
Claim 24
Dependent Claim
38 words
The method of claim 21, wherein the step of adjusting the level error signal is preceded by the step of limiting the level error signal to a value corresponding to acceptable operation within the low power operating regime.
Claim 25
Dependent Claim
56 words
The method of claim 22 further including the step of passing the level signal through a second adaptive network and passing the level error signal through a third adaptive network, before the step of adjusting the error signal, wherein the LaPlace transform co-efficients in the second and third adaptive networks are functions of the level signal.
Claim 26
Dependent Claim
33 words
The method of claim 22, further including the step of limiting the target flow signal to a value corresponding to reactor power operation within twice the range of the low power operating regime.
Claim 27
Dependent Claim
44 words
The method of claim 24, further including the step of passing the target flow signal through a first adaptive network after the step of limiting the target flow signal, the LaPlace transform co-efficients in said first adaptive network being functions of the power signal.
Claim 28
Dependent Claim
56 words
The method of claim 25, further including the step of passing the level signal through a second adaptive network and passing the level error signal through a third adaptive network, before the step of adjusting the error signal, wherein the LaPlace transform co-efficients in the second and third adaptive networks are functions of the level signal.
Claim 29
Dependent Claim
24 words
The method of claim 24, wherein the step of adjusting the level error signal includes increasing the gain factor as the feedwater temperature increases.
Claim 30
Dependent Claim
30 words
The method of claim 27, wherein the step of limiting the target flow signal limits the signal to a value within the range of about 0-20% of the reactor power.
Claim 31
Dependent Claim
88 words
The method of claim 21, further including the steps of: generating a main valve position signal indicative of the position of the main feedwater valve; generating an enable signal when the power signal is within a transition range that includes a portion of the low power regime and a portion of the higher power regime; and when the enable signal is generated, controlling the feedwater flow through the bypass valve in response to the target flow signal, the adjusted level error signal, and the main valve position signal.
Claim 32
Dependent Claim
28 words
The method of claim 29, wherein at a predetermined power level above the lower power regime, the step of controlling the feedwater flow includes closing the bypass valve.
Claim 33
Dependent Claim
24 words
Tee method of claim 21, wherein the step of adjusting the level error signal includes increasing the gain factor as the feedwater temperature increases.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-26 | 1993-09-25 | 1994-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-26 | 1997-09-25 | 1998-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-26 | 2001-09-25 | 2002-03-27 | $7700.00 | Window Closed / Lapsed |