Active Drain System for Supercritical Fluid Chromatography Separators
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Solution Overview
Problem
Current gas-liquid separators in preparative supercritical fluid chromatography systems face challenges with deterministic drainage of variable volume and viscosity liquid fractions, leading to inefficiencies and contamination due to rapid pressure changes and varying modifier viscosities, especially during gradient separations.
Innovation Solution
The implementation of an active drain system using specialized pumps that isolate discrete flow volumes, allowing controlled liquid mass flow over a wide range of rates and viscosities while restricting gas mass flow, thereby improving drainage efficiency and reducing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If passive flow restrictors or pressure-based drainage is used, then the system is simpler, but drainage becomes non-deterministic and vapor entrainment increases
Solution Approach 1:
The patent replaces passive mechanical flow restrictors and pressure-based drainage systems with an active pump system. The pump uses a valveless mechanism with a moving boundary (such as a reciprocating piston or flexible diaphragm) to create positive displacement flow, providing deterministic drainage control independent of pressure gradients and vapor entrainment.
Solution Approach 2:
The patent introduces an intermediary valveless pump mechanism between the separator and collection system. This pump acts as a mediator that decouples the drainage flow rate from the pressure differential, using its internal moving boundary to meter flow deterministically while preventing vapor from being pumped along with the liquid.
2Productivity
If rapid pressure reduction is used to expand CO2, then separation efficiency improves, but liquid fraction drainage becomes unpredictable
Solution Approach 1:
The patent replaces pressure-based passive drainage with an active valveless pump system that uses positive displacement mechanics. The pump's moving boundary creates flow through volumetric displacement rather than pressure differential, making drainage reliable and predictable even after rapid CO2 expansion in the separator.
3Loss of substance
If conventional drainage methods are used, then vapor removal is achieved, but liquid fraction loss increases
Solution Approach 1:
The patent introduces a valveless pump as an intermediary device between the separator and collection system. The pump's valveless design with a moving boundary creates unidirectional flow that selectively pumps liquid while excluding vapor, preventing vapor entrainment in the liquid fraction and reducing substance loss.
Solution Approach 2:
The patent applies local quality by creating different flow conditions at different locations in the drainage system. The valveless pump creates a high-velocity liquid flow path through its moving boundary while the vapor phase follows a different path, separating the two phases locally and preventing vapor contamination of the liquid fraction.
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 solution enables deterministic drainage of liquid fractions with reduced vapor entrainment, enhancing the precision and efficiency of fraction collection, even under varying conditions, and allowing for more flexible operation with different modifier viscosities.
Implementation Method 1
The pump operates using positive displacement to move liquid from the separator at a controlled rate.
Implementation Method 2
This rapid pressure reduction causes an immediate expansion of the CO2 component to a gas
Implementation Method 3
the original mobile phase of the flow line carried away from the back pressure regulator becomes biphasic with a very cold mixture of CO2 and modifier vapor and liquid modifier containing the dissolved solutes
Data Source
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AI summary
An apparatus and process to effectively create an active drain for high and low pressure gas-liquid separator. The invention accomplishes a deterministic drainage rate of variable volume and viscosity liquid fractions from the separator. The mechanisms and methods thereof create a flow path from the separator that dramatically favors controlled liquid flow over a wide range of flow rates and viscosities while restricting gas flow. The invention is a superior method of drainage over conventional systems that employ pressure, vacuum, isolation valves and/or passive flow restrictors to achieve drainage of the separators. The embodiments are primarily directed to the fields of preparative supercritical fluid chromatography (SFC) and supercritical fluid extraction (SFE). An advantage of one embodiment allows the economical conversion of typical HPLC systems to state of-the-art supercritical fluid chromatography (SFC) systems with minimal modification to system components.