External Thermal Modulator for GC Temperature Control

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Solution Overview

Problem

Existing chromatography systems face limitations in achieving precise temperature control and efficient sample modulation, particularly in two-dimensional gas chromatography, which affects the resolution and separation of volatile compounds.

Innovation Solution

A chromatography system incorporating a thermal modulator with a secondary oven and a heat pipe or thermosiphon system, positioned outside the chromatograph, allows for advanced temperature control and efficient heat removal, enabling narrower reinjection bands and faster modulation with standard capillary columns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the modulator is positioned inside the chromatograph, then the system structure is simpler, but the temperature control precision and heat removal efficiency deteriorate

Engineering Contradiction:

Improvesystem structureVSAvoidtemperature control precision

Core Design Contradiction:

Device complexityVSTemperature

Solution Approach 1:

The modulator is extracted from the interior of the chromatograph and positioned externally, connected via a transfer line. This extraction allows the modulator to have dedicated cooling mechanisms (heat pipe, thermosiphon system, or cooler disposed on the modulator) that can efficiently remove heat without interfering with the chromatograph's internal temperature zones, thereby improving temperature control precision.

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of operation

If conventional chromatography systems are used, then the system is easier to operate, but the resolution and separation of volatile compounds deteriorate

Engineering Contradiction:

Improveoperation simplicityVSAvoidresolution and separation

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The chromatography system is segmented into distinct functional zones: the chromatograph for initial separation, the transfer line for sample transport, and the external modulator with secondary oven for focused temperature control and reinjection. This segmentation allows each component to be optimized independently, with the modulator providing precise temperature management that enhances resolution and separation of volatile compounds without complicating overall operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The transfer line acts as an intermediary between the chromatograph and the external modulator, enabling the modulator to exert precise temperature control over the sample without requiring direct integration with the chromatograph's internal systems. This intermediary connection allows advanced temperature management techniques to be applied while maintaining ease of operation through modular design.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If standard capillary columns are used without advanced modulation, then the system is simpler, but the modulation speed and reinjection band width deteriorate

Engineering Contradiction:

Improvemodulation system complexityVSAvoidmodulation speed

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The external modulator with its dedicated heating and cooling mechanisms performs preliminary action by precisely controlling the temperature of the sample before reinjection into the secondary oven and subsequent analysis. The heat pipe or thermosiphon system pre-cools the modulator, and the heating elements can rapidly increase temperature when needed, achieving fast modulation speeds and narrow reinjection bands without requiring complex internal modifications to the chromatograph or special capillary columns.

Inventive Principle:

Principle #10Preliminary action

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 configuration enhances the resolution and separation of volatile compounds by achieving better temperature control and faster modulation, allowing for successful trapping at higher temperatures and reducing peak tailing, thereby improving the overall performance of two-dimensional gas chromatography.

Implementation Method 1

the gas chromatography system includes a heat pipe or a thermosiphon system that connects the modulator with the cooler. The heat pipe or the thermosiphon system is configured to remove heat from the modulator

Methodology Applied

Scientific EffectHeat pipe: Heat Pipe

Implementation Method 2

Methodology Applied

Scientific EffectThermosiphon: Thermosyphon

Implementation Method 3

The modulator includes a heater and a capillary column defining a void. The capillary column arranged in the void of the heater

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 4

The cooler is connected to the modulator and the modulator is arranged outside of the chromatograph

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentUS11609212B2Chromatography system

Publication Date: 2023.03.21 LECO CORP

AI summary

A method for applying a heating sequence for a modulator includes, during a first period of time, heating a first heating zone disposed along a length of the modulator without heating a second heating zone to cause a sample trapped from a first transfer line at an entrance of the modulator to move from the first heating zone to the second heating zone. The method also includes, during a second time period, withdrawing the heating of the first heating zone to prevent the sample from entering the modulator from the first transfer line. During a third time period, the method includes heating the second heating zone without heating the first heating zone to reinject the sample into a second transfer line.