LOW PRESSURE STEAM TURBINE SEAL ARRANGEMENT

摘要

A seal arrangement is installed between confronting co-planar portions of a low pressure steam turbine exhaust hood and a circular bulkhead that forms part of an exhaust duct structure of a steam turbine module. The seal arrangement forms a vacuum seal between the interior and exterior of the exhaust hood and comprises a flexible gasket in the form of an annular diaphragm. This diaphragm has a radially inner circumferential portion that seals with the bulkhead, a radially outer circumferential portion that seals with the exhaust hood, and a radially median resilient portion. Sealing is achieved by providing radially inner and outer clamping flanges operative to sealingly clamp inner and outer circumferential portions of the gasket to the bulkhead and the exhaust hood respectively. To enable quick access to the interior of the exhaust hood, the clamping flanges comprise upper and lower halves and the upper part of the gasket is sealed to the upper parts of the exhaust hood and the bulkhead by an arrangement of flanges and counter-flanges, the counter-flanges being releasably secured to outside surfaces of the exhaust hood and the bulkhead.