Sealing Assembly for Turbo-Compressor Thermal Distortion

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Solution Overview

Problem

Process gas turbine compressors used in nitric acid production experience gas leaks due to thermal distortions at the compressor housing parting lines, leading to the escape of harmful NO-containing gases over time.

Innovation Solution

A sealing arrangement with multiple grooves and seals, including a third groove charged with inert gas, and an outer groove for reduced pressure, effectively prevents gas leakage by using PTFE seals that can flow into thermal distortions and an outer groove for gas suction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a simple sealing arrangement is used at the compressor parting line, then the device complexity is low, but gas leaks occur due to thermal distortions

Engineering Contradiction:
Improvesealing reliabilityVSAvoidsealing arrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing arrangement is divided into multiple functional segments: a first seal for primary sealing, a second seal for secondary sealing, and a third groove for thermal compensation. This segmentation allows each component to address specific aspects of the sealing problem, improving overall reliability while keeping individual components relatively simple

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The third groove acts as an intermediary element between the two seals, filled with inert gas to provide thermal compensation. This intermediary component absorbs thermal expansions and distortions, preventing them from compromising the sealing interface between the two housing parts

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple seals and grooves are added to prevent gas leakage, then sealing reliability improves, but device complexity increases

Engineering Contradiction:
Improvesealing reliabilityVSAvoidsealing arrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Different regions of the sealing arrangement have specialized functions: the first groove contains a seal for primary sealing, the second groove contains a seal for secondary sealing, and the third groove provides thermal compensation. Each local region is optimized for its specific function, improving overall sealing reliability without requiring every component to be complex

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The third groove is filled with inert gas to create an inert environment that compensates for thermal distortions. This inert atmosphere prevents harmful gas contamination while the thermal compensation maintains seal effectiveness, improving reliability without adding mechanical complexity

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

3Temperature

If the sealing arrangement is subjected to high thermal load, then the compressor can operate at required temperatures, but thermal distortions cause gap enlargements and leaks

Engineering Contradiction:
Improveoperating temperatureVSAvoidsealing reliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The third groove is specifically designed to accommodate thermal expansion of the housing materials. By providing a compliant space filled with inert gas, the arrangement absorbs dimensional changes caused by thermal loading, preventing gap enlargements at the sealing interface while maintaining the required operating temperature

Inventive Principle:
Principle #37Thermal expansion

Solution Approach 2:

The sealing arrangement incorporates cushioning elements (the two seals in the first and second grooves) that are positioned beforehand to compensate for anticipated thermal distortions. These seals provide a buffer that maintains sealing contact even when thermal expansion creates gaps, ensuring reliability under high temperature operation

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Significantly reduces or prevents the escape of NO-containing gases, allowing multiple start-up cycles without leaks, and maintains a tight seal against the compressor parting joint arrangement.

Implementation Method 1

the high thermal load leads to thermal distortions at the parting lines of the compressor housing

Methodology Applied
Scientific EffectThermal distortion: Thermal Expansion

Implementation Method 2

PTFE seals that can flow into thermal distortions

Methodology Applied
Scientific EffectPTFE flow: Plasticity

Implementation Method 3

a third groove located between the first and second grooves which can be charged with a gas component via at least one opening

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Implementation Method 4

an outer groove, which can be brought to a pressure that is reduced compared to the ambient pressure via one or more openings

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Implementation Method 5

an outer groove for gas suction

Methodology Applied
Scientific EffectGas suction: Suction

Data Source

PatentEP2516047B1Sealing assembly for a process gas turbo-compressor
Publication Date: 2015.10.07 BASF SE
  • EP2516047B1 patent drawingFigure 1~2
  • EP2516047B1 patent drawingFigure 3

AI summary

A sealing assembly for a process gas turbo-compressor, which is used for example in the production of nitric acid for compressing highly corrosive gases, comprising a first partial joint, which can be brought into sealing contact with a second partial joint in order to prevent gas from passing through between the partial joints and escaping from the interior of the tank, a first seal in one of the partial joints in a first groove, which extends over the length of the partial joint and transversely in relation to the direction of a possible gas leakage between the partial joints, a second seal in one of the partial joints in a second groove, which extends over the length of the partial joint and transversely in relation to the direction of a possible gas leakage between the partial joints, and a third groove, which is arranged between the first and second grooves and to which a gas component can be applied via one or more openings.