Adjustable Movable Seal Ring for Rotary Machine Steam Turbine
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing seal structures for rotary machines, such as those in steam turbines, face challenges in maintaining consistent sealing performance due to thermal expansion and vibration, leading to potential contact between fins and the opposing surface, which results in abrasion and reduced sealing efficiency. The actuation timing of movable seal rings is not reliably controlled, especially during load drops or sudden steam-temperature changes, causing hysteresis and increased risk of contact.
Innovation Solution
A seal structure with an adjustable movable seal ring that utilizes an open/close valve to connect the high-pressure and low-pressure sides to the same pressure source, allowing for active control of the seal ring's position through fluid pressure, ensuring a consistent gap between the fins and the opposing surface, thereby enhancing sealing performance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gap between fins and the opposing surface is reduced to enhance sealing performance, then sealing performance is improved, but the risk of contact and abrasion increases due to thermal expansion and vibration
Solution Approach 1:
The seal ring is designed to be movable in the radial direction, allowing it to dynamically adjust its position based on operating conditions. The seal ring can move inward during rated operation to reduce the gap for better sealing, and move outward during start-up/shut-down to prevent contact, thus resolving the contradiction between sealing performance and contact prevention
Solution Approach 2:
The gap between fins and the opposing surface is made variable rather than fixed. By changing the radial position of the seal ring, the gap parameter can be optimized for different operating states: small during rated operation for sealing, and large during transient states to prevent contact
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution ensures reliable actuation of the movable seal ring, preventing contact between the fins and the opposing surface, maintaining optimal sealing performance during rated operation and reducing the risk of damage, while also enhancing the reliability of the seal structure by controlling the gap effectively.
Implementation Method 1
a movable seal ring which is movable in a substantially radial direction at least at a portion thereof in the circumferential direction and is biased outward by an elastic piece
Implementation Method 2
an inner circumferential surface of the movable seal ring receives outward pressure from the passing working fluid. This pressure gradually decreases toward a low-pressure portion side
Implementation Method 3
the rotating shaft and the stationary portion thermally expand due to the high-temperature steam introduced after start-up
Implementation Method 4
when the movable seal ring radially moves, a friction force acts between this side surface on the low-pressure portion side and the stationary portion
Data Source
AI summary
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.