| 摘要 |
<p>A method and apparatus for controlling the operation of a normally open bypass valve in a steam turbine air inleakage exhaust vent pipe. The valve is used to bypass a flowmeter connected in a bypass pipe parallel with the valve. The flowmeter provides signals indicative of bypassed flow. The method and apparatus compares the signals from the flowmeter to a reference signal corresponding to a first predetermined flow rate and generates a valve closure signal if the flow through the flowmeter is less than the predetermined flow rate. If the valve is closed, the signals from the flowmeter are used to display the actual air inleakage exhaust rate. If the flow exceeds a second predetermined value, a signal is generated to open the valve for bypassing the exhaust through the valve around the flowmeter. During the second mode of operation, the flowmeter indicates only approximate inleakage exhaust flow rate. If the flow drops below the first predetermined value, the valve is again closed and the flow rate is measured by the flowmeter.</p> |
