SEALING APPARATUS AND METHOD FOR STEAM TURBINES

摘要

The present invention provides a labyrinth seal apparatus and a method for reducing steam swirl in a steam turbine having an annular-shaped stationary portion (12) through which extends a rotating portion (14) rotatable about an axis (16). The proposed seal (10, 50, 100, 150) comprises a plurality of circumferentially adjacent arc-shaped seal carrier segments (20) adapted to be attached to the stationary portion (12), to form a seal ring (21). A plurality of arc-shaped sealing elements (24, 24A-H) are disposed axially spaced apart upon an inner face (22) of each seal carrier segment (22), wherein each of said plurality of sealing elements (24, 24A-H) extends radially inwardly toward said rotating portion (12). The proposed seal further includes a flow dam comprising an axially extending brush seal element (30, 30A, 30B) disposed upon said inner face (22) of each seal carrier segment (20). The flow dam brush seal element (30, 30A, 30B) is disposed between and perpendicular to a pair of axially adjacently spaced apart sealing elements (24A, 24B, 24D-H). Each said axially extending flow dam brush seal element (30, 30A, 30B) further extends radially inwardly toward said rotating portion (12) and is adapted to restrict a circumferential component of steam flow about said rotating portion (14).