Turbine Annular Gap Insert Ring for Erosion-Resistant Sealing
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Solution Overview
Problem
Existing turbine sealing methods, particularly in annular gaps, face challenges with erosion and corrosion, leading to inefficient sealing and difficulty in restoring the original seal when damage occurs, especially with non-erosion-corrosion-resistant steel and increased steam moisture.
Innovation Solution
A method involving an insert ring with a conical sealing section and axial fixation, which is inserted into a recess produced by a material-removing process, ensuring a reliable and efficient seal by minimizing interruptions in the inner surface and using fastening elements that are protected from the flow, allowing for easy insertion and secure clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing bands are secured by caulking wires in sealing band grooves, then the annular gap can be sealed, but the sealing bands can become detached due to erosion and corrosion
Solution Approach 1:
The invention extracts the sealing function from the original casing structure by inserting a separate insert ring into a recess. This insert ring carries the sealing bands and is made of erosion-corrosion-resistant material, separating the sealing function from the main turbine casing which is subject to erosion and corrosion.
Solution Approach 2:
The insert ring is made of erosion-corrosion-resistant material (such as stainless steel or nickel-based alloy) while the main casing can be made of less expensive material. This composite material approach provides localized protection where it is most needed - in the sealing area exposed to erosion and corrosion.
2Ease of repair
If sealing band grooves are eroded, then the original seal cannot be restored, but producing a new recess and inserting an insert ring restores the sealing function
Solution Approach 1:
The sealing system is segmented into a removable insert ring that can be independently replaced. When erosion or corrosion damages the sealing area, only the insert ring needs to be removed and replaced, not the entire turbine casing. This modular approach simplifies repair while ensuring reliable sealing restoration.
Solution Approach 2:
The insert ring is pre-formed with the correct geometry and sealing surfaces before insertion. This preliminary preparation ensures that when the ring is inserted into the recess, it immediately provides the correct sealing geometry without requiring complex in-situ machining or shaping operations.
3Ease of manufacture
If an insert ring is inserted axially into a recess, then insertion is simplified, but fastening elements must be protected from the flow
Solution Approach 1:
The fastening elements are arranged in the axial dimension (parallel to the insertion direction) rather than in the radial or circumferential directions. This dimensional arrangement allows the fastening elements to be protected from the flow while maintaining simple axial insertion, as the fastening features can be positioned on the axial faces of the insert ring.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for sealing an annular gap (11) in a turbine with a housing (1) and a rotor (2), which is arranged in the housing (1), is mounted to rotate about its central longitudinal axis, and is equipped with a plurality of stages of rotor blades (3), in which method a) an annular recess (16), which is arranged coaxially with respect to the rotor (2) and opposite the tips (9) of the rotor blades (3) of a stage, is provided in the housing (1) or in at least one element (31) attached to the housing, b) a more particularly subdivided insert ring (17), which is formed such that it can be inserted into the recess (16) in a form-fitting manner with play, is provided, c) the insert ring (17) is inserted into the recess (16), more particularly in that the insert ring (17) is pushed into the recess (16) at least substantially in the axial direction, and d) the insert ring (17) is fixed using securing elements (19) in such a way that an at least substantially axially directed clamping force is applied by means of the securing elements. The invention also relates to a turbine.