Pervaporation Control Shield for Liquid Degassing Systems
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Solution Overview
Problem
In liquid chromatography systems, solvent pervaporation through membranes can alter the relative concentrations of mobile phase solvents, affecting analytical accuracy, especially in low-throughput systems or those with incomplete flushing, leading to changes in solvent concentrations during analyte transportation.
Innovation Solution
A liquid degassing apparatus is designed to minimize pervaporation by creating a pervaporation control space between the membrane and a shield member, and attenuating pressure oscillations using pneumatic filtration in the evacuation line, thereby limiting solvent vapor exchange and maintaining consistent solvent concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vacuum pumps are programmed to maintain relatively low absolute pressures on the permeate side of the membrane to maximize degassing performance, then degassing efficiency is improved, but pervaporation of solvent components occurs leading to changes in mobile phase concentration
Solution Approach 1:
A shield member is introduced as an intermediary component between the membrane and the vacuum pump. This shield member defines a pervaporation control space that acts as a buffer zone, preventing direct interaction between the vacuum pump and the membrane permeate side, thereby reducing solvent vapor removal while maintaining degassing efficiency
Solution Approach 2:
The invention changes the pressure parameter distribution by creating a controlled pressure gradient in the pervaporation control space. The shield member allows pressure to be maintained at different levels in different zones, enabling optimization of both degassing performance and solvent concentration stability
2Reliability
If the permeate side of the degassing chamber is maintained at low pressure conditions to drive target gas transfer through the membrane, then gas degassing is enhanced, but pervaporative effects cause concentration changes in the mobile phase
Solution Approach 1:
The degassing chamber is segmented into functional zones by the shield member. The pervaporation control space is created as a distinct segment between the membrane and vacuum pump, allowing independent control of conditions in each zone to optimize both degassing and analytical accuracy
3Duration of action of stationary object
If mobile phase has relatively high residence time within the degassing chamber, then complete degassing is achieved, but pervaporation effects are amplified causing significant concentration changes
Solution Approach 1:
The shield member acts as a mediator that decouples the relationship between residence time and pervaporation extent. By introducing the pervaporation control space, the shield member allows mobile phase to remain in the chamber for complete degassing while preventing proportional increase in solvent loss
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 apparatus effectively limits pervaporation, maintains accurate solvent blends, and reduces cross-contamination between degassing chambers, ensuring reliable chromatographic analysis by controlling the permeate side environment and stabilizing pressures.
Implementation Method 1
a gas-permeable, liquid-impermeable membrane disposed in the chamber to separate the chamber into a permeate side and a retentate side
Implementation Method 2
vacuum pumps are typically programmed to maintain relatively low absolute pressures on the permeate side of the membrane
Implementation Method 3
A liquid degassing apparatus is arranged to limit pervaporation through a membrane, in one aspect, by establishing a pervaporation control space at a permeate side of the membrane
Data Source
AI summary
A liquid degassing apparatus is arranged to limit pervaporation through a membrane by attenuating pressure oscillations developed by a vacuum pump. The attenuation is obtained through a combination of one or more flow restrictors and added volume chambers fluidly interposed between the degassing chamber and the vacuum pump. The pressure oscillation attenuation may further inhibit cross-contamination of pervaporated solvents among a plurality of distinct degassing chambers.