MAIN SHAFT WATER SEALING APPARATUS

PROBLEM TO BE SOLVED: To provide a main shaft water sealing apparatus capable of restraining a water leakage from a runner back pressure chamber with a simple structure not only during the operation of a water turbine but at the start and stop and during a test run. SOLUTION: The main shaft water sealing apparatus includes a plurality of seal parts 4 installed at a space in the axial direction of a main shaft 2 at a portion where the main shaft 2 penetrates an upper cover 3; an injection port 21 provided facing the main shaft between the plurality of seal parts; a water intake 19 opened to the runner back pressure chamber 5 where water pressure rises with the rotation of a runner; a water supply pipe 7 connecting the water intake to the injection port; and a water supply tank 9 installed at an intermediate part of the water supply pipe. The water intake is installed in a position where pressure that can pump up water in the runner back pressure chamber during the operation of the water turbine is generated in the runner back pressure chamber, and the water supply tank is installed in a position not lower than the height required to inject, from the injection port by gravity, water of minimum pressure required for sealing the seal part during the operation of the water turbine. COPYRIGHT: (C)2011,JPO&INPIT