Abstract: Circumferentially extending sealing segments (45) are disposed about a rotary component (16) and have seal face (34) carrying a plurality of labyrinth seal teeth (36) and a brush seal (37). The segments are movable between large and small clearance positions relative to the rotor at start-up and steady-state operating conditions, respectively. In one form, springs (31) bias the segments radially outwardly at start-up and steam pressure displaces the segments to the small clearance positions at steady-state operations. In a further embodiment, springs bias the segment for movement to the small clearance position, the extent of movement being determined by thermal expansion of centering rings mounting the segments to the stationary components.

Abstract: A segmented seal ring and spring system for very low pressure drop zones in steam turbines for minimizing leakage between rotating and stationary components, and preventing damage and wear thereto, including a segmented seal ring, with first springs biased against the seal segments to urge the segments radially inwardly toward a small clearance position of the seal ring with respect to the turbine shaft secondary springs to counter the weight of the segments; with the combination of said springs gently urging the seal segments into the small clearance position while allowing clearance enlargement with small resulting forces on the shaft during periods of misalignment and rubbing.

Abstract: A variable clearance packing ring includes a plurality of circumferentially extending segments disposed in a generally dovetail-shaped slot in the stationary component of a machine having a rotor rotatable about an axis, the packing ring including an arcuate seal face in opposition to the rotor and axially extending flanges within the dovetail slot. Pins project axially from opposite sides of the stationary component for location between the flanges and sealing faces of the segments. A centering ring is mounted on the pins for each segment and has a coefficient of thermal expansion greater than the coefficient of thermal expansion of the segment.

Abstract: A rotary machine has a stationary component with circumferential grooves and a rotatable component, as well as annular sealing segments movable toward and away from the rotating component. To prevent circumferential displacement of the lower side annular segments by gravity forces and enable the lowermost segment in the lower housing to be moved radially inwardly, the side segments of the lower housing are supported adjacent the casing midline in a manner preventing downward movement and enabling radial inward and outward movement. Generally Z-shaped clips are disposed in the dovetail groove of the stationary component with the tab at the upper end of the clip engaging a stop on the stationary component and the radially inwardly directed tab on the lower end of the clip engaging in a recess of the segment. Consequently, the segment, upon radial inward movement, pivots the clip about an axis adjacent the casing midline, enabling radial inward and outward movement and preventing circumferential displacement.