Loading patent…
AssigneesWestinghouse Electric Corp., Foster Wheeler Energy Corporation
InventorsMorton H. Binstock, Robert L. Criswell
Estimating the term…
A steam blending control is provided for two or more boilers in an electric power plant. To blend an oncoming boiler with an on-line boiler, the oncoming boiler is fired to a pressure ramp setpoint and outlet steam is isolated from the plant turbine and directed through position controlled bypass valve means. When steam temperature and pressure conditions are matched, the oncoming boiler isolation valve is opened and the bypass flow then existing is stored in a memory. The oncoming boiler bypass flow is cut back with total oncoming boiler steam flow controlled to the memorized flow valve as a setpoint. Flow from the on-line boiler is cut back under load control as the oncoming boiler flow to the plant turbine is increased. Deblending is implemented in a similar manner.
An electric power plant control system for controlling the blending of steam from the output of at least one oncoming boiler with the steam from the output of an on-line boiler, each boiler having a high pressure turbine bypass valve and an isolation valve, said system comprising means for controlling the fuel supply to the on-line boiler to satisfy steam pressure demand under varying plant load conditions, means for generating a pressure ramp setpoint for the oncoming boiler, means for controlling the fuel supply to the oncoming boiler to satisfy steam pressure demand from said pressure ramp generating means, means for sensing actual bypass steam flow and turbine steam flow from the oncoming boiler, means for controlling the oncoming boiler bypass valve position to control bypass steam flow as a function of the pressure ramp setpoint, means for sensing and comparing the outlet boiler pressures, memory means for recording the outlet steam flow from the oncoming boiler when boiler outlet pressures are matched and the oncoming boiler isolation valve is opened for blending of the boiler outlet steam flows, means responsive to said memory means and said oncoming boiler flow sensing means for controlling said oncoming boiler fuel supply controlling means to hold the outlet steam flow from the oncoming boiler substantially constant, and means for progressively operating said oncoming boiler bypass valve controlling means after the oncoming boiler isolation valve is opened to close the oncoming boiler bypass valve and smoothly blend the oncoming boiler steam flow with the on-line boiler steam flow as said on-line boiler fuel supply controlling means cuts back on on-line boiler fuel to satisfy steam pressure demand with reduced outlet steam flow from the on-line boiler.
Dependencies are inferred from the claim text.