CN-122017099-A - Thermal conductivity detector and gas chromatograph provided with same

Abstract

The invention provides a thermal conductivity detector and a gas chromatograph provided with the thermal conductivity detector. The upstream portion of the flow path is accommodated in the cell body. A hot wire for detecting the thermal conductivity of the sample gas is housed in the upstream portion. The sample gas is guided to the exhaust line in the downstream portion through the flow path. The flow path is insulated by the insulation part to avoid the temperature of the sample gas passing through the exhaust pipeline from decreasing below the liquefaction temperature of the sample gas. Or at least a portion of the exhaust line including the downstream end is provided so as to be attachable to and detachable from the other portion of the flow path.

Inventors

• NAKAMA YUJI

Assignees

• 株式会社岛津制作所

Dates

Publication Date

20260512

Application Date

20190912

Priority Date

20180913

Claims (5)

1. 1. A thermal conductivity detector for a gas chromatograph, comprising: a flow path having a first portion and a second portion downstream of the first portion for directing sample gas through the first portion and the second portion to a discharge port of the second portion; A housing accommodating the first portion; A heating device accommodated in the housing; A heating element accommodated in the first portion for detecting the thermal conductivity of the sample gas, and A heat-retaining portion for retaining heat in the flow path so as to prevent the temperature of the sample gas passing through the second portion from decreasing to a temperature equal to or lower than the liquefaction temperature of the sample gas, The shell is provided with a heat insulation part, at least one part of the second part is positioned outside the heat insulation part, and the heat preservation part is arranged at the part outside the heat insulation part of the second part.
2. 2. A thermal conductivity detector according to claim 1, wherein, The heat retaining portion is mounted to the second portion to prevent the temperature of the sample gas passing through the second portion from decreasing below the liquefaction temperature of the sample gas.
3. 3. A thermal conductivity detector according to claim 2, wherein, The length of the second portion outside the heat insulator is set to a length that prevents the temperature of the sample gas discharged from the second portion from decreasing below the liquefaction temperature.
4. 4. A thermal conductivity detector according to any one of claims 1 to 3, The heat-retaining portion includes a temperature adjusting portion for adjusting the temperature of the sample gas.
5. 5. A gas chromatograph is provided with: a sample vaporizing section that generates a sample gas by vaporizing a sample; a column for separating components of the sample gas generated by the sample vaporizing section, and A thermal conductivity detector according to any one of claims 1 to 3, Wherein the thermal conductivity detector detects thermal conductivity of the sample gas of each component separated by the column.

Description

Thermal conductivity detector and gas chromatograph provided with same The present application is a divisional application of application number 201910863960.3, entitled "thermal conductivity detector and gas chromatograph equipped with the thermal conductivity detector", having application date 2019, 9, 12. Technical Field The present invention relates to a thermal conductivity detector for a gas chromatograph and a gas chromatograph provided with the thermal conductivity detector. Background In gas chromatographs, for example, a thermal conductivity detector is used for analyzing a sample. The thermal conductivity detector described in us patent 7185527 has a cavity configured with a hot wire (filament). The sample gas and the reference gas are alternately introduced into the cavity while the hot wire is heated to a fixed temperature. At this time, the heat of the filament is extracted by the heat conduction of the introduced gas, and the resistance value of the filament changes. Therefore, the thermal conductivity of the sample gas is measured by measuring how much the resistance value of the hot wire changes when the sample gas flows through the cavity relative to the resistance value of the hot wire when the reference gas flows through the cavity. The sample gas and the reference gas having passed through the cavity are discharged to the outside of the thermal conductivity detector through a pipe connected to the cavity. Disclosure of Invention As described above, the thermal conductivity detector is provided with a pipe (hereinafter referred to as an exhaust pipe) for discharging the sample gas introduced into the flow path in which the hot wire is disposed to the outside of the thermal conductivity detector. In the gas chromatograph, when a flow path of the thermal conductivity detector is clogged, the thermal conductivity detector needs to be replaced with a new thermal conductivity detector. However, thermal conductivity detectors are expensive. Therefore, it is difficult to reduce the running cost of the gas chromatograph. The invention aims to provide a thermal conductivity detector capable of reducing the operation cost of a gas chromatograph and the gas chromatograph with the thermal conductivity detector. As described above, it is known in the prior art that a gas chromatograph is clogged in a flow path of a thermal conductivity detector. However, the clogging of the flow path is recognized as a phenomenon indicating the replacement period of the thermal conductivity detector, and a structure for preventing the clogging of the flow path is not considered. The present inventors have repeatedly conducted various experiments and examinations to identify the cause of the flow path blockage, and as a result, have paid attention to that the blockage of the flow path occurs in a downstream portion of the flow path in many cases. The downstream portion of the flow path is located outside the housing and is exposed to the atmosphere having a temperature lower than that of the sample gas. Therefore, it is considered that the cause of the exhaust pipe clogging is that the sample gas at a high temperature after gasification is cooled and condensed or solidified in the exhaust pipe. Accordingly, the present inventors have changed the idea from the common knowledge of replacing the thermal conductivity detector due to the clogging of the exhaust pipe, studied the technique of continuously using the thermal conductivity detector by preventing the clogging of the flow path together with the above-described problems, and proposed the invention shown below. (1) The thermal conductivity detector according to one aspect of the present invention is a thermal conductivity detector for a gas chromatograph, and includes a flow path having a first portion and a second portion located downstream of the first portion, a discharge port for guiding a sample gas to the second portion through the first portion and the second portion, a case accommodating the first portion, a heating element accommodated in the first portion for detecting thermal conductivity of the sample gas, and a heat retaining portion for retaining heat in the flow path so as to prevent a temperature of the sample gas passing through the second portion from decreasing to a temperature equal to or lower than a liquefaction temperature of the sample gas. In the thermal conductivity detector, a first portion of the flow path is accommodated in the housing. Thus, a second portion of the flow path downstream of the first portion is external to the housing. A heating element for detecting the thermal conductivity of the sample gas is housed in the first portion. The sample gas is guided to the discharge port of the second portion through the first portion and the second portion of the flow path. The flow path is insulated by the insulation part to avoid the temperature of the sample gas passing through the second part from decreasing below the liquefaction te