Seal Gas Liquid Detection for Non-Contacting Gas Seals
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Solution Overview
Problem
Current gas seal systems for non-contacting gas seals in compressors and rotating equipment face failures due to liquid contamination in the seal gas, which is not effectively detected or prevented, leading to operational losses and delays, especially in high-pressure applications where initial gas composition analysis is unreliable and changes with time.
Innovation Solution
A monitoring and control system that includes an evanescent wave sensor to detect liquid contaminants in the seal gas supply conduit, combined with pressure and temperature sensors, and a programmable logic device to provide warnings or initiate corrective actions, ensuring the seal gas remains clean and dry by comparing sensed data against stored phase information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional leakage monitoring is used to evaluate seal health, then the system is simple to operate, but it is insufficient to detect liquid contamination and prevent seal failures
Solution Approach 1:
The system performs preliminary detection of liquid contaminants in the seal gas supply before the liquid can reach and damage the seal faces. By detecting liquids upstream and providing advance warning, the system prevents seal failures before they occur, rather than merely monitoring seal performance after damage has begun
Solution Approach 2:
The evanescent wave sensor acts as an intermediary detection device that indirectly senses liquid contaminants in the gas stream without requiring direct contact with the seal mechanism. This intermediary approach enables reliable liquid detection while maintaining system simplicity through non-intrusive monitoring
2Loss of information
If initial gas composition analysis is performed, then some information about gas makeup is obtained, but the analysis is unreliable and changes with time, leading to liquid condensation
Solution Approach 1:
The system uses the process gas itself as the monitoring medium. The evanescent wave sensor detects liquid contaminants directly in the flowing seal gas, utilizing the gas stream's own properties for self-diagnosis rather than relying on external composition analysis that may be outdated or inaccurate
Solution Approach 2:
The system provides continuous real-time feedback on liquid contaminant presence in the seal gas supply. This ongoing monitoring allows the control system to respond to changing gas composition and liquid condensation risks dynamically, rather than relying on static initial analysis
3Device complexity
If no liquid detection system is installed, then the system remains simple, but liquid condensate reaches the seal chambers causing seal failures and operational losses
Solution Approach 1:
The system replaces complex mechanical liquid separation devices with an optical evanescent wave sensing system. This substitution detects liquid contaminants non-intrusively through optical means, avoiding the need for complex mechanical knock-out drums, separators, or other heavy liquid removal equipment
Solution Approach 2:
The evanescent wave sensor detects liquid contaminants through changes in optical properties of the gas stream. When liquid is present, it alters the evanescent wave characteristics, providing a detectable signal change that indicates liquid contamination without requiring visual inspection or complex analysis
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
The system effectively prevents liquid condensate from reaching the seal chambers, providing advanced warnings and corrective actions to maintain seal integrity, especially in high-pressure applications, thus reducing operational losses and improving reliability.
Implementation Method 1
an evanescent wave sensor in the conduit to sense the presence of liquid in the seal gas
Data Source
AI summary
A monitoring and control system for a seal gas supply system for a non-contacting gas seal. The supply includes several gas conditioning elements or units. The monitoring and control system includes an evanescent wave sensor to sense the presence of liquid in the seal gas. Multiple sensors to sense the temperature and pressure of the treated seal gas are disposed at the outlet of the conditioning elements. A programmable logic device is provided with information regarding the phase of the gas at various pressures and temperatures and compares the sensed data to the baseline data. Recognition of liquid concentrate results in an output signal.