Isolation Valve Liquid Purging to Prevent Contamination and Cavitation
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Solution Overview
Problem
Existing purging methods using gases like steam and nitrogen in isolation valves can lead to contamination, changes in process fluid chemistry and density, and cavitation in slurry pumps, which can damage equipment.
Innovation Solution
The use of hydrocarbons distilled in a fractionation tower as a liquid purge medium in isolation valves, maintained at a positive pressure greater than the process media, to prevent contamination and cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas purge media (steam or nitrogen) is used in isolation valves, then the process fluid can be prevented from leaving the line, but the purge media may leak into the process and cause contamination, change chemistry and density, and lead to cavitation in slurry pumps
Solution Approach 1:
The patent changes the physical state of the purge media from gas to liquid. Liquid purge media is used instead of gas purge media (steam or nitrogen) to prevent the harmful effects of gas leakage into the process fluid. The liquid purge media is maintained at a temperature below the dew point to ensure it remains in liquid phase and does not cause cavitation or contamination issues associated with gas purge media.
Solution Approach 2:
The patent introduces liquid purge media as an intermediary substance between the process fluid and the valve body. This liquid purge media acts as a barrier that prevents process fluid from leaving the line while avoiding the contamination and cavitation problems caused by gas purge media. The liquid purge media is selected to be compatible with the process fluid and not cause harmful chemical reactions.
2Reliability
If gas purge media is used in isolation valves, then the process fluid can be prevented from leaving the line, but the density and chemistry of the process fluids may change
Solution Approach 1:
The patent changes the physical state of the purge media from gas to liquid to prevent chemical reactions and density changes in the process fluid. Liquid purge media does not cause the same chemistry changes and density variations that occur when gas purge media mixes with process fluids.
3Reliability
If gas purge media is used in isolation valves, then the process fluid can be prevented from leaving the line, but cavitation may occur in slurry pumps
Solution Approach 1:
The patent changes the physical state of the purge media from gas to liquid to prevent cavitation in slurry pumps. Liquid purge media maintained below the dew point temperature does not vaporize and form bubbles that could cause cavitation when entering the slurry pump system, thereby eliminating this harmful effect while maintaining isolation valve sealing reliability.
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
This approach effectively prevents contamination and cavitation, maintaining the integrity of the process fluid and reducing the risk of equipment damage, while also being environmentally friendly by utilizing a recycled purge media.
Implementation Method 1
a liquid purge medium under a positive pressure ensures the process fluid does not leave the line
Implementation Method 2
hydrocarbons distilled in a fractionation tower as a liquid purge media
Data Source
AI summary
A system and method for purging an isolation valve using a liquid purge medium.