Thermal Conductivity Detector Coating for Gas Chromatograph Exhaust
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Solution Overview
Problem
The high cost of replacing thermal conductivity detectors in gas chromatographs due to clogged exhaust pipes, which is caused by condensation or solidification of vaporized sample gases, and the potential corrosion of these pipes during cleaning.
Innovation Solution
A thermal conductivity detector with a flow path and heating element, where a first coating resistant to cleaning fluids is applied on the inner surfaces to prevent corrosion and a second coating with higher resistance than the materials used is applied on the heating element to protect it from cleaning fluids, allowing for the reuse of the detector by dissolving adhered substances without damaging the pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If cleaning fluid is used to remove adhered substance from the exhaust pipe, then the clogging is removed and the detector can be reused, but the inner surface of the exhaust pipe may be corroded
Solution Approach 1:
A coating layer is applied to the inner surface of the exhaust pipe to serve as an intermediary between the cleaning fluid and the pipe material. This coating resists corrosion from the cleaning fluid while allowing the cleaning fluid to effectively remove adhered substances, thus protecting the pipe integrity during the cleaning process
Solution Approach 2:
The exhaust pipe is constructed with a composite structure consisting of the base pipe material and a protective coating layer. The coating layer has specific properties that make it resistant to cleaning fluids while maintaining the overall structural integrity and functionality of the exhaust pipe
2Reliability
If thermal conductivity detector is replaced when exhaust pipe is clogged, then the detector functionality is restored, but the running cost of gas chromatograph increases
Solution Approach 1:
Instead of discarding the entire thermal conductivity detector when the exhaust pipe becomes clogged, the invention enables recovery and reuse of the detector by providing a cleaning mechanism. The exhaust pipe can be cleaned in place using cleaning fluid that flows through the pipe, removing adhered substances and restoring functionality without requiring detector replacement
Solution Approach 2:
The exhaust pipe is designed to be self-cleaning through a built-in cleaning fluid supply system. Cleaning fluid can be introduced through the exhaust pipe to remove adhered substances, allowing the detector to service itself and eliminate the need for costly replacements
3Measurement precision
If high temperature sample gas is introduced into the thermal conductivity detector, then the thermal conductivity detection is enabled, but condensation or solidification occurs in the exhaust pipe causing clogging
Solution Approach 1:
The temperature parameter of the exhaust pipe is modified by introducing cleaning fluid that maintains a temperature preventing condensation and solidification of sample gas components. This parameter change prevents the formation of adhered substances in the exhaust pipe while allowing high temperature sample gas to pass through for detection
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 solution enables the reuse of thermal conductivity detectors, reducing the need for frequent replacements and lowering the operational costs of gas chromatographs by preventing corrosion and effectively removing adhered substances from the exhaust pipes.
Implementation Method 1
the heat of the filament is drawn according to the thermal conduction of the introduced gas, which causes a change in the resistance value of the filament. Therefore, the thermal conductivity of the sample gas can be measured by measuring how much the resistance value of the filament when the sample gas flows through the cavity has changed
Implementation Method 2
a heat retention unit configured to keep the first portion warm
Implementation Method 3
a first coating having resistance to a cleaning fluid for removing an adhered substance due to the sample gas is formed on an inner surface of the second portion of the flow path
Data Source
AI summary
A thermal conductivity detector includes a first pipe passage and an exhaust pipe passage. The first pipe passage is accommodated in a cell block together with a heating device. The exhaust pipe passage has an outlet port at the downstream end, and most of the exhaust pipe passage including the downstream end is drawn out of the cell block. The heating device maintains the space in the cell block at a temperature capable of vaporizing the sample. A filament is accommodated in the first pipe passage. The gas passing through the first pipe passage is discharged out of the thermal conductivity detector through the exhaust pipe passage outlet port. On the inner surface of the exhaust pipe passage, a coating having resistance to a cleaning fluid for removing the adhered substance due to the sample gas is formed.