Seal structure for rotary machine

摘要

A seal structure partitions a high-pressure portion and a low-pressure portion including spring-back seal rings on the high-pressure side, including ACC seal rings and fins on the low-pressure side. The ACC seal rings have an adjustable movable seal ring which is a movable seal ring that is movable in a substantially radial direction at a portion thereof and which partitions a high-pressure side steam chamber and a medium-pressure side steam chamber with the fins and a circumferential surface, and including a pressure equalizing pipe that connects the low-pressure side of the adjustable movable seal ring to a high-pressure outlet portion, is provided with an adjusting pipe that connects, on the high-pressure side steam chamber side of the ACC seal rings, a high-pressure dummy to the same high-pressure outlet portion as the medium-pressure side steam chamber, and an open/close valve in the adjusting pipe.

主权项

1. A seal structure for partitioning a high-pressure portion and a low-pressure portion of a rotary machine, the seal structure comprising: at least one stage of high-pressure side seal rings disposed on a high-pressure side of the seal structure, the high-pressure side seal rings being held in a stationary portion, so as to oppose a circumferential surface of a rotating member; at least one stage of seal rings disposed on a low-pressure side of the seal structure, the seal rings being held in a stationary portion, so as to oppose the circumferential surface of the rotating member; and fins protruding in a ring manner, and being disposed in at least one of the seal rings and the rotating member, wherein each of the seal rings has an adjustable movable seal ring, which is movable in a substantially radial direction, and at least at a portion thereof in the circumferential direction, and which is biased outward in the radial direction by an elastic piece, and which is configured to partition the high-pressure portion and the low-pressure portion with the fins and an opposing surface opposing the fins, a holding member for holding the adjustable movable seal ring is arranged so as to dispose a gap between an inner circumferential surface of the holding member and an outer circumferential surface of the adjustable movable seal ring, and the adjustable movable seal ring includes a communication hole communicating between a high-pressure side of the adjustable movable seal ring and the gap, the seal structure further comprising a connecting flow path connected to a single pressure source, on a low-pressure side of the adjustable movable seal ring, the connecting flow path continuously communicating between the low-pressure side of the adjustable movable seal ring and the single pressure source;
an adjusting flow path connecting the high-pressure side of the adjustable movable seal ring to the single pressure source; and an open/close valve disposed in the adjusting flow path and being configured to open and close the adjusting flow path, the open/close valve being open during start-up operation of the rotary machine and being closed during rated operation of the rotary machine, the open/close valve continuously communicating between the high-pressure side of the adjustable movable seal ring and the single pressure source when the open/close valve is opened; and a controller configured to determine whether the rotating member and the stationary portion are in a thermally stable state and control opening and closing of the open/close valve depending on the result of the determination.