Thermal Conductivity Detector Flow Path Heating

Solution Overview

Problem

The flow path of thermal conductivity detectors in gas chromatographs often becomes clogged due to condensation of high-temperature sample gases, leading to increased maintenance costs and downtime, as conventional solutions focus on replacing the detectors rather than preventing clogging.

Innovation Solution

A thermal conductivity detector design that includes a flow path with a warm retention system, where the upstream portion is housed within a casing and the downstream portion is kept warm using temperature retainers or insulators to prevent sample gas cooling and condensation, allowing continuous use without replacing the entire detector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thermal conductivity detector is used to analyze sample gas, then the thermal conductivity measurement function is achieved, but the flow path becomes clogged due to condensation of high-temperature sample gas

Engineering Contradiction:

Improveflow path畅通性VSAvoidsample gas condensation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The exhaust pipe is heated in advance before the sample gas arrives, preventing condensation from occurring. The heating element raises the pipe temperature above the dew point of the sample gas, so when the hot sample gas flows through, it remains in gaseous state and does not condense on the pipe walls.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The temperature parameter of the exhaust pipe is changed from ambient temperature to elevated temperature. By controlling the pipe temperature to be higher than the dew point of the sample gas, the physical state of the sample gas is maintained as gas phase, preventing condensation and clogging.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the flow path becomes clogged, then the thermal conductivity detector must be replaced, but this increases running cost

Engineering Contradiction:

Improvedetector continuous operationVSAvoiddetector replacement cost

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The exhaust pipe is heated in advance before the sample gas arrives, preventing condensation from occurring. The heating element raises the pipe temperature above the dew point of the sample gas, so when the hot sample gas flows through, it remains in gaseous state and does not condense on the pipe walls.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The high temperature of the sample gas, which was previously causing condensation harm, is converted into a benefit by using it to maintain the exhaust pipe temperature. The sample gas itself serves as a heating source for the pipe, preventing condensation without requiring additional energy input.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the exhaust pipe is heated to prevent condensation, then energy consumption increases, but flow path clogging is prevented

Engineering Contradiction:

Improveflow path畅通性VSAvoidexhaust pipe heating energy

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The high temperature of the sample gas, which was previously causing condensation harm, is converted into a benefit by using it to maintain the exhaust pipe temperature. The sample gas itself serves as a heating source for the pipe, preventing condensation without requiring additional energy input.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The exhaust pipe heating system uses the sample gas itself as the heat source. The hot sample gas flowing through the pipe provides the necessary thermal energy to maintain the pipe temperature above the dew point, making the system self-sufficient and eliminating the need for external heating energy input.

Inventive Principle:

Principle #25Self-service

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 effectively prevents clogging of the flow path, reducing the need for frequent detector replacements and lowering the operational costs of gas chromatographs by maintaining the sample gas temperature above its liquefaction point.

Implementation Method 1

a temperature retainer that keeps the flow path warm such that a temperature of the sample gas that passes through the second portion does not decrease to a temperature equal to or lower than a liquefaction temperature of the sample gas

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

the filament loses heat due to the thermal conduction of the led gas, and a resistance value of the filament changes

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11428676B2Thermal conductivity detector and gas chromatograph including same

Publication Date: 2022.08.30 SHIMADZU CORP

AI summary

An upstream portion of a flow path is stored in a cell block. A filament for detecting thermal conductivity of a sample gas is stored in the upstream portion. The sample gas is led to a downstream portion of an exhaust pipe path through the flow path. The flow path is kept warm by a temperature retainer such that the temperature of the sample gas that passes through the exhaust pipe path does not decrease to a temperature equal to or lower than a liquefaction temperature of the sample gas. Alternatively, at least one portion including a downstream end of the exhaust pipe path is provided to be attachable to and detachable from another portion of the flow path.