Steam Turbine Inner Casing Support Beam Design
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Solution Overview
Problem
Large low-pressure steam turbines face challenges in reducing steam leakage and improving installation efficiency due to deformation under vacuum loads, leading to increased gaps between rotating and stationary units, which affects turbine performance and prolongs the installation process.
Innovation Solution
The steam turbine design incorporates support beams with sliding connections and a height adjustment mechanism to isolate the inner casing from outer casing deformation, ensuring a consistent gap and reducing steam leakage, while allowing for on-site adjustments to minimize installation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the outer casing is supported by foot plates fixed to the foundation, then the outer casing can be stabilized, but the inner casing and rotor bearing are susceptible to deformation under vacuum loads
Solution Approach 1:
The support system is segmented into independent support paths: the outer casing is supported by foot plates fixed to the foundation, while the inner casing is supported by support beams that are slide-connected to the outer casing. This segmentation allows the inner casing to be isolated from deformation of the outer casing, maintaining stable supporting positions for the rotor bearing even when the outer casing deforms under vacuum loads.
2Reliability
If the inner casing is supported by support beams slide-connected to the outer casing, then deformation of the outer casing is isolated from the inner casing, but the installation process becomes more complex
Solution Approach 1:
The support beam acts as an intermediary element between the outer casing and the inner casing. It is slide-connected to the outer casing, allowing it to accommodate deformation of the outer casing while maintaining a stable supporting position for the inner casing. This intermediary connection isolates the inner casing from deformation without requiring complex adjustment mechanisms during installation.
3Loss of energy
If the gap between rotating and stationary units is made small to prevent steam leakage, then turbine performance is improved, but installation becomes more difficult due to deformation
Solution Approach 1:
The support beams are pre-installed and adjusted during the installation process to account for expected deformation of the outer casing under vacuum loads. By performing preliminary adjustment of the support beam positions, the gap between the rotating and stationary units can be maintained at the optimal small value to prevent steam leakage, while accommodating deformation without complicating the installation process.
Data Source
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AI summary
The steam turbine of an embodiment has: an outer casing; an inner casing housed in the outer casing; a turbine rotor penetrating the inner casing and the outer casing; and a support beam provided in the outer casing, extending in an axial direction of the turbine rotor, and supporting the inner casing, and is disposed on a foundation. The outer casing has outer casing support portions provided in both end portions of the outer casing in the axial direction of the turbine rotor and supported by the foundation. The support beam has beam end portions provided in both end portions in the axial direction of the turbine rotor. The outer casing support portion has a support surface supporting the beam end portion. Further, the outer casing includes a height adjustment mechanism capable of accessing the beam end portion from the outside of the outer casing.