Adaptive Turbine Stage With Undercut Neck For High Pressure Drops
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Solution Overview
Problem
Steam turbines face challenges in handling large pressure drops across a limited number of stages, requiring adaptive stages that can manage pressure differences up to 25bar effectively while withstanding high temperatures.
Innovation Solution
An adaptive stage design featuring a fixed ring and a slide ring with a gland, inner and outer axial bearings, and a radial bearing, where the fixed ring has a neck with a circumferential undercut, allowing the slide ring to rotate relative to the fixed ring, and utilizing high-temperature steel materials like X22CrMoV12-1 for durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a conventional adaptive stage design is used, then the structure is simpler, but it cannot handle pressure differences above 16 bar
Solution Approach 1:
The fixed ring is segmented into functionally distinct regions: a main body for structural support and a protruding neck region for bearing support. This segmentation allows the neck to be optimized specifically for withstanding high pressure forces while the main body maintains overall structural integrity, enabling the stage to handle pressure differences up to 25 bar.
Solution Approach 2:
The circumferential undercut is positioned specifically at the base of the neck where bearing loads are concentrated. This localized structural feature provides enhanced load-bearing capacity precisely where needed, allowing the design to withstand high pressure forces without requiring increased complexity throughout the entire structure.
2Adaptability or versatility
If the pressure difference handling capability is increased to 25 bar, then the operational range is improved, but the structural complexity increases due to the neck and undercut design
Solution Approach 1:
The neck structure serves multiple functions simultaneously: it provides a mounting surface for the inner axial bearing, creates the circumferential undercut for load distribution, and maintains the structural connection between the rotating and fixed components. This multi-functionality allows the design to achieve 25 bar pressure handling capability without adding separate components, thus avoiding increased complexity.
3Temperature
If high-temperature materials like X22CrMoV12-1 are used, then the temperature resistance is improved, but the manufacturing difficulty increases
Solution Approach 1:
The material specification is changed to X22CrMoV12-1 steel, which has superior high-temperature properties. This parameter change in material composition enables the adaptive stage to operate at temperatures up to 505°C while maintaining mechanical strength and structural integrity, despite the increased manufacturing challenges associated with this high-performance alloy.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Adaptive stage (1) for high pressure drops in a turbine, in particular in a steam turbine, comprising a fixed ring (10) and a slide ring (20), a gland (30), an inner axial bearing (40) and an outer axial bearing (50), a radial bearing (60), a radial insert (70) and an axial insert (80), whereby the rolls (41) of the inner axial bearing (40) contact a first area (15) of the fixed ring (10) and a first area (25) of the slide ring (20), the rolls (42) of the outer axial bearing (50) contact a second area (16) of the fixed ring (10) and a first area (85) of the axial insert (80) and the rolls (61) of the radial bearing (60) contact the outer side (32) of the gland (30) and the inner side (21) of the slide ring (20), and wherein the fixed ring (10) comprises at that side which is arranged next to the slide ring (20) a neck (2) with a circumferential undercut (6).