Geared Compressor Rotor Composite Design for Cryogenic Strength

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Solution Overview

Problem

Turbo compressors face challenges in low-temperature operations due to the risk of brittle fracture, as existing designs are not adequately protected against cold embrittlement, and there is a need for materials that can maintain mechanical strength and durability in cryogenic applications.

Innovation Solution

A geared compressor rotor design where the sealing segment and impeller hub form a common, integrally connected area using a low-temperature-resistant material, while the toothed segment is made of a harder, high-strength material, with a Hirth connection ensuring rotational fixity and minimizing thermal imbalance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the pinion shaft and impeller are made from different materials to meet high mechanical requirements, then the strength and durability are improved, but the complexity of manufacturing and assembly increases

Engineering Contradiction:
Improvemechanical strengthVSAvoidmanufacturing and assembly complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The rotor shaft is constructed as a composite structure with a pinion shaft made of steel for high mechanical strength and an impeller made of cold-tough material for low-temperature resistance. This composite design allows each component to be optimized for its specific functional requirements while being manufactured and assembled as an integrated unit, reducing overall complexity.

Inventive Principle:
Principle #40Composite materials

2Reliability

If the entire rotor is made from cold-tough material to protect against brittle fracture, then the resistance to cold embrittlement is improved, but the mechanical strength and gear dimensions increase leading to higher costs and mechanical losses

Engineering Contradiction:
Improveresistance to cold embrittlementVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

Different materials are applied to different regions of the rotor shaft based on local requirements: the pinion shaft region uses steel for high mechanical strength where gears operate at higher temperatures, while the impeller region uses cold-tough material for low-temperature resistance where cryogenic gases are present. This local differentiation optimizes both strength and cold embrittlement resistance while minimizing overall material usage and costs.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2414684B1Geared compressor rotor for cold gas applications
Publication Date: 2013.01.23 SIEMENS AG
  • EP2414684B1 patent drawingFigure 1

AI summary

The invention relates to a geared compressor rotor (2) for cold gas applications having a pinion shaft (16) having a gear tooth segment (18) having gear teeth (14), at least one wheel (6) having a wheel hub (8) and a sealing segment (10) arranged between the gear tooth segment (14) and the wheel hub (8) that bears a seal (12). Said geared compressor rotor (2) also has high strength even in low temperature applications when the wheel hub (8) and the sealing segment (10) form a common, one-piece, connected region (4) made of a first material and the gear tooth segment (18) is produced from a second material.