Driving method of axial flow turbine with discharge valve

摘要

PURPOSE:To make the proper control of increase in a total flow rate possible by branching a water course to provide a axial flow water turbine on its one branched passage and a discharge valbve on its other branched passage respectively, and controlling the discharge valve or the like so as to temporarily decrease a total opening area at quick load variation. CONSTITUTION:An axial flow water turbine with a discharge valve has branched water courses, and is provided with a water turbine branch pipe 1 and a discharge valve branch pipe 6 on its upstream side. The branch pipe 1 is provided with the axial flow water turbine having a guide vane 4 and a runner 5, and the branch pipe 6 is provided with the discharge valve 10 having a gate 7 and a cone 8 for changing the opening area of the pipe 6. The downstream pipes 2, 9 of the branch pipes 1, 6 are mutually joined on their downstream sides. In this case, at quick load variation such as load shutdown, the discharge valve 10 is opened for a fixed time immediately after the quick load variation so that increase in the opening area of the discharge valve 10 may become less than decrease in the opening area or the guide vane 4. Thus the mutual opening areas of both the branch pipes 1, 6 can be temporarily lessened than their total opening area before the quick load variation.