Turbine Annular Gap Sealing With an Axially Clamped Insert Ring
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Solution Overview
Problem
In turbines, especially those with non-erosion and non-corrosion resistant steel blades, annular gaps between rotor blades and the casing can lead to erosion and detachment of sealing strips, making it difficult to restore the original sealing due to missing material in eroded grooves.
Innovation Solution
A method involving the creation of an annular depression in the casing for inserting a split, erosion-resistant insert ring, which is axially tensioned using fastening elements to ensure reliable sealing and prevent leakage, allowing for easy restoration of the original sealing without interrupting the inner cylindrical surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sealing strips are fastened using caulking wires in sealing grooves, then the sealing structure is simple and easy to manufacture, but the sealing strips become detached due to erosion and corrosion in high moisture environments
Solution Approach 1:
The sealing system is segmented into modular components: sealing strips, retaining clips, and support rings that can be independently replaced. This allows the sealing strips to be easily removed and replaced without damaging the grooves, solving the detachment problem while maintaining ease of manufacture.
Solution Approach 2:
Retaining clips and support rings are introduced as intermediary elements between the sealing strips and the casing grooves. These intermediaries provide reliable mechanical retention and distribute loads, preventing direct erosion and corrosion of the sealing strips while maintaining a simple overall structure.
2Reliability
If new sealing strips are installed in eroded sealing grooves, then the original sealing can be restored, but it is difficult to do so because material is missing from the eroded grooves
Solution Approach 1:
The damaged sealing grooves are completely removed (taken out) from the system. Instead of attempting to repair or refill the eroded grooves, the invention extracts the problematic regions and replaces them with new modular sealing components that fit into freshly created recesses.
Solution Approach 2:
The sealing grooves are pre-prepared by removing eroded material before installing new sealing strips. Support rings are also pre-installed to provide a stable foundation, ensuring that new sealing strips can be properly seated without encountering eroded surfaces.
3Reliability
If the inner cylindrical surface is interrupted to fasten sealing strips, then the sealing strips can be secured, but the sealing effectiveness is reduced and material is wasted
Solution Approach 1:
The fastening mechanism is moved from the radial dimension (interrupting the inner cylindrical surface) to the axial dimension. Retaining clips and support rings fasten sealing strips axially, leaving the inner cylindrical surface continuous and intact, thus preventing material loss while maintaining secure fastening.
Data Source
AI summary
Provided is a method for sealing an annular gap in a turbine with a housing and a rotor, in which method a) an annular recess, which is arranged coaxially with respect to the rotor and opposite the tips of the rotor blades of a stage, is provided in the housing or in at least one element attached to the housing, b) a subdivided insert ring, which is formed such that it can be inserted into the recess in a form-fitting manner with play, is provided, c) the insert ring is inserted into the recess, more particularly in that the insert ring is pushed into the recess at least substantially in the axial direction, and d) the insert ring is fixed using securing elements in such a way that an at least substantially axially directed clamping force is applied by means of the securing elements. A turbine is also provided.