| 摘要 |
PURPOSE:To take a proper protective action against any trouble of a low pressure turbine bypass system by detecting the actual flow rate of cooling water and computing the allowable quantity of steam which is flown into the bypass system of a low pressure turbine on the basis of the detection so as to control the actual quantity of inflow steam according to the computed value. CONSTITUTION:In case cooling spray water is fully fed to a steam temperature reduction device via a spray control valve 12, a flow detector 20 generates a signal of a high value, which goes into a low value priority circuit 28 as a large value via a function generator 23-2, a divider 27 and a function generator 23-3. As a result, the signal from a proportional integral controller 25-1 is selected in said circuit so that the quantity of bypass steam measured by a flow detector 22 is controlled by a bypass valve 8 as to be kept at the pressure value of reheated steam set by a pressure detector 18. In case the insufficient spray water may be supplied on account of a sticking trouble or so of a control valve 12, the output signal of the flow detector 20 becomes low. The low value priority circuit 28 is thereby selected to the function generator 23-3 side so that the quantity of bypass steam is restrained to the quantity which is allowed by the quantity of actually supplied spray water. The system may be thus protected properly. |
