초록 ▼

In a combined cycle plant, a process flow demand signal is applied to multiple sequentially operated boiler feedwater valves through a single manual/automatic (M/A) station. Each valve is positioned in accordance with its position/flow characterization so that the total feedwater flow to the boiler

In a combined cycle plant, a process flow demand signal is applied to multiple sequentially operated boiler feedwater valves through a single manual/automatic (M/A) station. Each valve is positioned in accordance with its position/flow characterization so that the total feedwater flow to the boiler satisfies the flow demand. To provide for bumpless manual to automatic transfer, valve position signals are characterized with the inverse of the respective valve characterizations in the flow region not covered by a lower order valve. The characterized outputs are set to zero in flow regions covered by a lower order valve. A high selection of the characterized outputs is performed and the selected signal corresponds to the process flow demand value which will enable a manual to automatic transfer without causing an upset in steam generator process flow or electric power generation.

대표청구항 ▼

A multiple sequential valve control for at least two parallel valves which regulate the flow through a single path comprising an automatic flow control which generates an automatic flow demand in response to predetermined process variables in the automatic mode, means for generating a manual flow de

A multiple sequential valve control for at least two parallel valves which regulate the flow through a single path comprising an automatic flow control which generates an automatic flow demand in response to predetermined process variables in the automatic mode, means for generating a manual flow demand, a manual/automatic station for selectively transmitting the automatic or manual flow demand, means for controlling the position of a first valve over a first range of the path flow in response to the applied Flow demand in accordance with a first flow/position characterization, means for controlling the position of a second valve over a second range of the path flow in response to the applied flow demand in accordance with a second flow/position characterization, means for sensing the position of each of said valves, means for generating an equivalent flow demand for said valves from outputs of said valve position sensing means, and means for coupling the equivalent flow demand to said automatic flow control in the manual mode to track the automatic flow control output to the manual demand and thereby enable bumpless manual/automatic transfer.