Method and apparatus for eliminating thermal bowing using brush seals in the diaphragm packing area of steam turbines

摘要

In a steam turbine, a combined brush and labyrinth seal is provided between a diaphragm web and a sealing surface on a rotatable component radially outwardly of the rotor surface. The contact between the brush seal and sealing surface lies along an axially upstream projecting flange of an annular platform such that heat generated by frictional contact between the bristles and the sealing surface has minimal effect on the rotor surface and hence rotor dynamics. A backup labyrinth seal is provided between the web and platform. Additionally, axially upstream projecting flanges are provided on the downstream buckets and which flanges are spaced radially outwardly of the rotor surface and lie in registration with the diaphragm web. Labyrinth teeth seal between the diaphragm web and the bucket flanges serving as a backup seal.