Provided are a method and system for improving control of a steam generator level for preventing oscillation of the steam generator level in a nuclear power plant. In order to prevent oscillation of a steam generator level and resultant shutdown of a nuclear reactor, which may be caused when a high-level priority control function is frequently and repeatedly turned on/off as the steam generator level is excessively increased, by improving a feedwater control system in the nuclear power plant, a proportional integral control value may be controlled to be reduced, and thus, output while a certain condition is met after a high-level priority mode is deactivated or a signal instructing to enter the high-level priority control mode may be controlled not to be output.

A system includes the HRSG having an economizer disposed along a fluid flow path, and a drum disposed along the fluid flow path downstream of the economizer. The HRSG also includes a drum level control module configured to modulate an amount of the fluid provided to the drum along the fluid flow path and a supplemental control module configured to control an amount of the fluid in a different manner than the drum level control module. The heat recovery steam generator also includes a drum level event controller configured to monitor a rate of change of a level of the fluid in the drum. If the rate of change is over a threshold value, a signal goes to the supplemental control. If the rate of change is less than or equal to the threshold value, the signal goes to the drum level control module.

A system includes the HRSG having an economizer disposed along a fluid flow path, and a drum disposed along the fluid flow path downstream of the economizer. The HRSG also includes a drum level control module configured to modulate an amount of the fluid provided to the drum along the fluid flow path and a supplemental control module configured to control an amount of the fluid in a different manner than the drum level control module. The heat recovery steam generator also includes a drum level event controller configured to monitor a rate of change of a level of the fluid in the drum. If the rate of change is over a threshold value, a signal goes to the supplemental control. If the rate of change is less than or equal to the threshold value, the signal goes to the drum level control module.

Aqueous working fluid (WF) steam generation system including: pressure vessel containing heat exchanger; enclosed combustion air (CA) chamber; burner; another heat exchanger outside pressure vessel; and WF conduit. Heat exchanger includes first: enclosed WF chamber having WF input and output apertures (IOA); and enclosed CA passageway communicating with CAIOA and passing through enclosed WF chamber. Enclosed CA chamber includes second: enclosed WF chamber having WFIOA; and enclosed CA passageway communicating with CAIOA. Burner is connected to second CA input aperture. Another heat exchanger includes third: enclosed WF chamber having WFIOA; and enclosed CA passageway communicating with CAIOA. WF conduit connects third WF output aperture to second WF input aperture. Second WF output aperture is connected to first WF input aperture; and second CA output aperture is connected to first CA input aperture; and first CA output aperture is connected to third CA input aperture.

Aqueous working fluid (WF) steam generation system including: pressure vessel containing heat exchanger; enclosed combustion air (CA) chamber; burner; another heat exchanger outside pressure vessel; and WF conduit. Heat exchanger includes first: enclosed WF chamber having WF input and output apertures (IOA); and enclosed CA passageway communicating with CAIOA and passing through enclosed WF chamber. Enclosed CA chamber includes second: enclosed WF chamber having WFIOA; and enclosed CA passageway communicating with CAIOA. Burner is connected to second CA input aperture. Another heat exchanger includes third: enclosed WF chamber having WFIOA; and enclosed CA passageway communicating with CAIOA. WF conduit connects third WF output aperture to second WF input aperture. Second WF output aperture is connected to first WF input aperture; and second CA output aperture is connected to first CA input aperture; and first CA output aperture is connected to third CA input aperture.

A low water sensor testing device having an initial piping unit connected to a hot water boiler and also connected to a first three way purge valve unit, which valve unit is, in turn, connected to a T-shaped piping unit and affixed within the stem portion of which there is a low water level sensor unit with the T-shaped piping unit being further connected to a second three way purge valve unit, wholly equivalent to the first valve unit, with the second valve unit being connected to an adapter unit, in turn, also connected to outflow piping carrying boiler heated water via outflow piping to the heating system of a residential or commercial structure.

A low water cutoff (LWCO) device having a probe features a signal processor or processing module configured to receive signaling containing information about a difference in conductance between samples of a foam/unstable fluid line for a predetermined foam difference count that are measured on at least one test channel and sensed by the probe arranged inside a boiler, including a steam or hot water boiler or burner; and provide corresponding signaling containing information to turn OFF the boiler, based upon the signaling received.

A low water cutoff (LWCO) device having a probe features a signal processor or processing module configured to receive signaling containing information about a difference in conductance between samples of a foam/unstable fluid line for a predetermined foam difference count that are measured on at least one test channel and sensed by the probe arranged inside a boiler, including a steam or hot water boiler or burner; and provide corresponding signaling containing information to turn OFF the boiler, based upon the signaling received.