Thermal conductivity detector and gas chromatography provided with same

Abstract

The invention provides a thermal conductivity detector and a gas chromatograph provided with the same. The upstream portion of the flow path is housed in the tank body. A heating wire for detecting the thermal conductivity of the sample gas is housed in the upstream portion. The sample gas is guided to the downstream exhaust line through the flow path. The heat preservation part is used for preserving the heat of the flow path so as to prevent the temperature of the sample gas passing through the exhaust pipeline from being reduced to below the liquefaction temperature of the sample gas. Alternatively, 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.

Description

[0001] This application is a divisional application of the application filed on September 12, 2019, with application number 201910863960.3 and invention title "Thermal Conductivity Detector and Gas Chromatograph Equipped with the Thermal Conductivity Detector". Technical Field

[0002] This invention relates to a thermal conductivity detector for a gas chromatograph and a gas chromatograph equipped with the thermal conductivity detector. Background Technology

[0003] In a gas chromatograph, a thermal conductivity detector is used, for example, to analyze a sample. The thermal conductivity detector described in U.S. Patent No. 7,185,527 has a cavity equipped with a hot filament. With the hot filament heated to a fixed temperature, sample gas and reference gas are alternately introduced into the cavity.

[0004] At this point, the thermal conductivity of the introduced gas draws heat from the hot wire, causing a change in the resistance of the hot wire. Therefore, the thermal conductivity of the sample gas is determined by measuring how much the resistance of the hot wire changes when the sample gas flows through the cavity compared to the resistance of the hot wire when the reference gas flows through the cavity. The sample gas and reference gas, having passed through the cavity, are discharged to the outside of the thermal conductivity detector through a pipe connected to the cavity. Summary of the Invention

[0005] As described above, a pipe (hereinafter referred to as an exhaust pipe) is provided in the thermal conductivity detector for venting the sample gas introduced into the flow path equipped with the hot wire to the outside of the thermal conductivity detector.

[0006] In gas chromatographs, if the flow path of the thermal conductivity detector becomes clogged, the detector needs to be replaced with a new one. However, thermal conductivity detectors are expensive, making it difficult to reduce the operating costs of the gas chromatograph.

[0007] The purpose of this invention is to provide a thermal conductivity detector that can reduce the operating cost of a gas chromatograph and a gas chromatograph equipped with the thermal conductivity detector.

[0008] As mentioned above, blockage in the flow path of the thermal conductivity detector in gas chromatographs is well-known. However, this blockage has been identified as a phenomenon indicating the replacement period of the thermal conductivity detector, without considering the structure designed to prevent blockage.

[0009] To determine the cause of flow path blockage, the inventors conducted various experiments and investigations. The results showed that most blockages occurred in the downstream section of the flow path. This downstream section is located outside the casing and is exposed to the atmosphere, which is at a lower temperature than the sample gas. Therefore, it is believed that the blockage in the exhaust pipe is caused by the high-temperature sample gas, after vaporization, being cooled and condensed or solidified within the exhaust pipe.

[0010] Therefore, the inventors changed their thinking from the common technical knowledge of replacing thermal conductivity detectors due to blockage of the exhaust pipe, and studied the technology of continuing to use thermal conductivity detectors by preventing blockage of the flow path together with the above-mentioned issues, and proposed the invention shown below.

[0011] (1) A thermal conductivity detector of one aspect of the present invention is a thermal conductivity detector for a gas chromatograph, comprising: a flow path having a first portion and a second portion located downstream of the first portion for guiding a sample gas through the first portion and the second portion to an outlet of the second portion; a housing housing the first portion; a heating element housing in the first portion for detecting the thermal conductivity of the sample gas; and a heat preservation portion for heat preservation of the flow path to prevent the temperature of the sample gas passing through the second portion from dropping below the liquefaction temperature of the sample gas.

[0012] In this thermal conductivity detector, a first portion of the flow path is housed within a housing. Therefore, a second portion of the flow path, located downstream of the first portion, is located outside the housing. A heating element for detecting the thermal conductivity of the sample gas is housed within the first portion. The sample gas is guided through the first and second portions of the flow path to the outlet of the second portion. A heat-insulating section is used to maintain the flow path temperature to prevent the temperature of the sample gas passing through the second portion from dropping below its liquefaction temperature.

[0013] This structure prevents the high-temperature sample gas from being cooled and condensed or solidified in the downstream section of the flow path. Therefore, flow path blockage is prevented, eliminating the need to replace the thermal conductivity detector in the gas chromatograph. Consequently, the operating costs of the gas chromatograph are reduced.

[0014] (2) Alternatively, the insulation section may include a first insulation section installed in the housing and a second insulation section installed in the second part. In this case, the entire flow path is insulated. This makes it easier to prevent flow path blockage.

[0015] (3) Alternatively, the insulation part can be installed in the housing to prevent the temperature of the sample gas passing through the second part from dropping below the liquefaction temperature of the sample gas. In this case, the flow path can be prevented from being blocked by not installing the insulation part in the second part.

[0016] (4) Alternatively, the length of the second part outside the housing can be set to prevent the temperature of the sample gas discharged from the second part from dropping below the liquefaction temperature. In this case, it is easier to prevent flow path blockage by not installing a heat insulation part on the second part.

[0017] (5) Alternatively, the insulation section may include a heat insulation component for insulating the sample gas from the outside of the housing. In this case, the flow path can be easily insulated to prevent the temperature of the sample gas passing through the second section from dropping below the liquefaction temperature of the sample gas.

[0018] (6) Alternatively, the insulation section may include a temperature adjustment section for adjusting the temperature of the sample gas. In this case, the flow path can be easily insulated to prevent the temperature of the sample gas passing through the second section from dropping below the liquefaction temperature of the sample gas.

[0019] Next, the inventors noticed that blockages in the flow path mostly occur in the downstream part of the flow path, and proposed the invention shown below.

[0020] (7) The thermal conductivity detector of other aspects of the present invention is a thermal conductivity detector for a gas chromatograph, comprising: a flow path having a first portion and a second portion located downstream of the first portion for guiding sample gas through the first portion and the second portion to an outlet of the second portion; a housing housing the first portion; and a heating element housing the first portion for detecting the thermal conductivity of the sample gas, wherein at least a portion of the second portion including the downstream end is configured to be detachable relative to other portions of the flow path.

[0021] In this thermal conductivity detector, a first portion of the flow path is housed within a housing. Therefore, a second portion of the flow path, downstream of the first portion, is located outside the housing. A heating element for detecting the thermal conductivity of the sample gas is housed within the first portion. The sample gas is guided through the first and second portions of the flow path to the outlet of the second portion. At least a portion of the second portion of the flow path, including its downstream end, is configured to be detachable relative to the other portions of the flow path.

[0022] According to this structure, even if blockage occurs in the downstream section of the flow path, the thermal conductivity detector can continue to be used by replacing at least a portion of the second part of the flow path, including the downstream end. Therefore, it is not necessary to replace the entire thermal conductivity detector. This reduces the operating cost of the gas chromatograph. Furthermore, it shortens the downtime of the gas chromatograph.

[0023] (8) A gas chromatograph of another aspect of the present invention comprises: a sample vaporization section that generates a sample gas by vaporizing a sample; a column for separating the components of the sample gas generated by the sample vaporization section; and a thermal conductivity detector of one or more aspects, wherein the thermal conductivity detector detects the thermal conductivity of the sample gas of each component separated by the column.

[0024] In this gas chromatograph, a sample gas is generated by vaporizing the sample in a sample vaporization section. The components of the sample gas generated by the sample vaporization section are separated using a column. The thermal conductivity of each component of the sample gas separated by the column is detected using the aforementioned thermal conductivity detector.

[0025] The thermal conductivity detector prevents flow path blockage, thus eliminating the need to replace the detector in the gas chromatograph. Alternatively, even if blockage occurs in the downstream section of the flow path, the thermal conductivity detector can continue to be used by replacing at least a portion of the second part of the flow path, including the downstream end. This reduces the operating costs of the gas chromatograph. Attached Figure Description

[0026] Figure 1 This is a block diagram showing the structure of the gas chromatograph according to the first embodiment.

[0027] Figures 2(a) and 2(b) are schematic diagrams showing a first modified example of the thermal conductivity detector.

[0028] Figure 3 This is a schematic diagram illustrating a second modified example of a thermal conductivity detector.

[0029] Figure 4 This is a block diagram showing the structure of a first modified example of a gas chromatograph.

[0030] Figure 5 This is a block diagram showing the structure of a second modified example of a gas chromatograph.

[0031] Figure 6 This is a block diagram illustrating the structure of the gas chromatograph according to the second embodiment.

[0032] Figure 7 This is a schematic diagram showing a first modified example of an exhaust pipe.

[0033] Figure 8 This is a schematic diagram showing a second modified example of the exhaust pipe. Detailed Implementation

[0034] The following description, with reference to the accompanying drawings, illustrates an embodiment of the present invention involving a thermal conductivity detector and a gas chromatograph equipped with the thermal conductivity detector.

[0035] [1] First implementation method

[0036] (1) Overview of the structure and basic operation of a gas chromatograph

[0037] Figure 1 This is a block diagram illustrating the structure of the gas chromatograph according to the first embodiment. Figure 1 As shown, the gas chromatograph 100 involved in this embodiment mainly includes a gas tank 10, a flow adjustment unit 20, a sample vaporization unit 30, a column 40, a flow adjustment unit 50, a switching valve 60, a thermal conductivity detector 70, and a control unit 80.

[0038] The gas tank 10 stores a carrier gas for guiding the sample gas (described later) to the column 40 and the thermal conductivity detector 70. For example, an inert gas such as helium is used as the carrier gas.

[0039] Gas tank 10 supplies carrier gas to two flow adjustment units 20 and 50 via branch pipelines. One flow adjustment unit 20 supplies a specified flow rate of carrier gas to the sample vaporization unit 30 based on the control of the control unit 80.

[0040] The sample vaporization section 30 includes an injector and a vaporization chamber. A sample is injected into the vaporization chamber of the sample vaporization section 30 via the injector. The internal atmosphere of the vaporization chamber is maintained in a state of sample vaporization. Thus, the sample injected into the vaporization chamber is vaporized inside the chamber. The sample vaporization section 30 supplies the vaporized sample to the column 40 while mixing it with carrier gas supplied from the flow rate adjustment section 20. In the following description, the gas containing components of the sample vaporized in the sample vaporization section 30 is collectively referred to as sample gas.

[0041] Column 40 is housed within a column furnace (not shown). In column 40, the components of the sample gas supplied from the sample vaporization section 30 are separated. Column 40 supplies the sample gas separated for each component to the sample inlet line 76 of the thermal conductivity detector 70 (described later).

[0042] The flow adjustment unit 50, under the control of the control unit 80, supplies a specified flow rate of carrier gas to the switching valve 60. The switching valve 60, for example, is a three-way solenoid valve, connected to the flow adjustment unit 50 and to the two carrier inlet lines 75a and 75b of the thermal conductivity detector 70 (described later). The flow adjustment unit 50, under the control of the control unit 80, supplies carrier gas from the gas tank 10 to one of the carrier inlet lines 75a and 75b.

[0043] Furthermore, as a structure for supplying carrier gas passing through the flow regulating unit 50 to one of the two carrier inlet pipes 75a and 75b, a switching mechanism including multiple control valves and branch pipes can be used instead of the switching valve 60. For example, the main pipe is connected to the flow regulating unit 50, and two branch pipes are connected to the carrier inlet pipes 75a and 75b respectively. In addition, two control valves are provided on each of the two branch pipes. In this case, by controlling the opening and closing states of the two control valves, the carrier gas supplied from the flow regulating unit 50 can be selectively supplied to one of the two carrier inlet pipes 75a and 75b of the thermal conductivity detector 70.

[0044] The thermal conductivity detector 70 according to this embodiment includes a first conduit 71, a second conduit 72, a third conduit 73, a fourth conduit 74, a carrier introduction conduit 75a, 75b, a sample introduction conduit 76, and an exhaust conduit 77, all extending in a straight line. The first conduit 71, the second conduit 72, the third conduit 73, the fourth conduit 74, the carrier introduction conduit 75a, 75b, the sample introduction conduit 76, and the exhaust conduit 77 are examples of flow paths. The first conduit 71 and the exhaust conduit 77 are examples of the first and second parts of the flow path, respectively.

[0045] These multiple conduits are formed, for example, by metal piping. Furthermore, the first to fourth conduits 71 to 74 of the thermal conductivity detector 70, together with the heating device 70H, are housed within a cell block 78. The cell block 78 is an example of a housing. The cell block 78 is manufactured by machining and joining multiple plate-like metal members.

[0046] The first conduit 71 and the second conduit 72 are formed to extend towards each other and parallel to each other. The third conduit 73 is formed to connect one end of the first conduit 71 to one end of the second conduit 72, and the fourth conduit 74 is formed to connect the other end of the first conduit 71 to the other end of the second conduit 72. A heating filament F is housed inside the first conduit 71. On the other hand, no heating filament F is housed inside the second conduit 72. The heating filament F is an example of a heating element.

[0047] On the third pipeline 73, a first gas inlet 73a, a second gas inlet 73b, and a third gas inlet 73c are arranged side by side in sequence. Among the first gas inlet 73a to the third gas inlet 73c, the first gas inlet 73a is closest to the first pipeline 71, and the third gas inlet 73c is closest to the second pipeline 72.

[0048] The carrier introduction conduit 75a is formed to extend from the first gas introduction section 73a to the outside of the pool body 78. The sample introduction conduit 76 is formed to extend from the second gas introduction section 73b to the outside of the pool body 78. The carrier introduction conduit 75b is formed to extend from the third gas introduction section 73c to the outside of the pool body 78.

[0049] A gas outlet 74a is provided on the fourth pipe 74. An exhaust pipe 77 is formed to extend from the gas outlet 74a to the outside of the pool body 78. A through hole is formed in the gas outlet 74a. Thus, the internal space of the fourth pipe 74 is connected to the internal space of the exhaust pipe 77. The exhaust pipe 77 has an outlet 77e on the outside of the pool body 78.

[0050] The heating device 70H is controlled by the control unit 80 to maintain the space inside the pool 78 at a temperature similar to that in the vaporization chamber of the sample vaporization section 30 or in the column furnace used to house the column 40. For example, a cartridge heater is used as the heating device 70H. The pool 78 is surrounded by insulation 79. The insulation 79 can be, for example, glass wool or other components.

[0051] The control unit 80, for example, is composed of a CPU (central processing unit) and memory, or a microcomputer, and controls the operation of each component of the gas chromatograph 100 as described above. In addition, the control unit 80 in this example also includes a drive circuit for driving the hot filament F and a detection circuit for detecting changes in the resistance of the hot filament F.

[0052] The aforementioned switching valve 60 is used to switch between a first state and a second state, wherein the first state is a state in which carrier gas is supplied to one carrier inlet pipe 75a at a predetermined period (e.g., about 100 msec), and the second state is a state in which carrier gas is supplied to the other carrier inlet pipe 75b at a predetermined period.

[0053] In this case, inside the third conduit 73 of the thermal conductivity detector 70, when the switching valve 60 is in the first state, the pressure in the space on the side of the first gas inlet 73a is higher than the pressure in the space on the side of the second gas inlet 73b. Therefore, the sample gas supplied to the sample inlet conduit 76 flows through the second conduit 72 together with a portion of the carrier gas introduced from the first gas inlet 73a. Furthermore, the remaining portion of the carrier gas introduced from the first gas inlet 73a flows through the first conduit 71 as a reference gas.

[0054] On the other hand, inside the third conduit 73 of the thermal conductivity detector 70, when the switching valve 60 is in the second state, the pressure in the space on the side of the third gas inlet 73c is higher than the pressure in the space on the side of the second gas inlet 73b. Therefore, the sample gas supplied to the sample inlet conduit 76 flows through the first conduit 71 together with a portion of the carrier gas introduced from the third gas inlet 73c. ​​The remaining portion of the carrier gas introduced from the third gas inlet 73c flows through the second conduit 72.

[0055] Therefore, in the control unit 80, the thermal conductivity of the sample gas is measured based on the change between the resistance value of the hot wire F when the reference gas passes around the hot wire F and the resistance value of the hot wire F when the sample gas passes around the hot wire F.

[0056] (2) Insulation section

[0057] As described above, in the thermal conductivity detector 70, the space inside the cell 78 is maintained at a temperature similar to the vaporization temperature of the sample using a heating device 70H. In contrast, most of the exhaust pipe 77, which extends from the inside of the cell 78 to the outside, is exposed to ambient air (e.g., around 25°C). Therefore, the sample gas passing through the exhaust pipe 77 is cooled and condensed or solidified at its downstream end. Consequently, when the sample gas is analyzed multiple times, condensed or solidified sample accumulates at the downstream end of the exhaust pipe 77, causing blockage. This problem becomes more pronounced when the sample's liquefaction temperature is high or its concentration is high.

[0058] Therefore, in this embodiment, a heat insulation member 1 is installed on the portion of the exhaust pipe 77 leading from the tank 78 to serve as a heat insulation part to prevent the temperature of the discharged sample gas from dropping below its liquefaction temperature. The heat insulation member 1 can be formed from the same component as the heat insulation member 79, or it can be formed from other components. Figure 1 In the structure, the heat insulation part is composed of heat insulation components 1 and 79. Heat insulation component 79 and heat insulation component 1 are examples of the first heat insulation part and the second heat insulation part, respectively.

[0059] exist Figure 1 In the example, the heat insulation element 1 is installed such that it covers the entire outer peripheral surface of the exhaust pipe 77 extending from the pool body 78, but the invention is not limited thereto. Figures 2(a) and 2(b) are schematic diagrams showing a first modified example of the thermal conductivity detector 70. As shown in Figure 2(a), the heat insulation element 1 may also be installed such that it covers the outer peripheral surface of the downstream portion of the exhaust pipe 77. Alternatively, as shown in Figure 2(b), the heat insulation element 1 may be installed such that it covers the outer peripheral surface of the exhaust pipe 77 excluding the downstream portion.

[0060] Thus, the heat insulation component 1 can be installed in such a way that it only covers a portion of the outer periphery of the exhaust pipe 77 extending from the pool body 78. In addition, the heat insulation component 79 installed on the pool body 78 functions as a heat insulation part. If the protruding length of the exhaust pipe 77 extending from the pool body 78 is set short to avoid the temperature of the sample gas discharged from the exhaust pipe 77 dropping below the liquefaction temperature, the thermal conductivity detector 70 may not include the heat insulation component 1.

[0061] exist Figure 1 In the examples of Figures 2(a) and 2(b), the heat insulation part is heat insulation component 1 or heat insulation component 79, but the present invention is not limited to this. Figure 3 This is a schematic diagram showing a second modified example of the thermal conductivity detector 70. (As shown) Figure 3 As shown, the thermal conductivity detector 70 includes a temperature adjustment unit 2 instead of the heat insulation element 1.

[0062] The temperature regulating unit 2 is, for example, an electric heater, but it can also be a Peltier element or other components such as a heating medium. The temperature regulating unit 2 is mounted to the exhaust pipe 77 via a block-shaped mounting member 3 to generate heat to prevent the temperature of the sample gas discharged from the exhaust pipe 77 from dropping below its liquefaction temperature. The heat generated by the temperature regulating unit 2 can also be... Figure 1 The control unit 80 controls.

[0063] Mounting member 3, for example, is formed of a component with high thermal conductivity such as aluminum or copper, and is used to hold the temperature adjustment unit 2 and transfer the heat generated by the temperature adjustment unit 2 to the exhaust pipe 77. Mounting member 3 may cover the entire outer circumference of the exhaust pipe 77 extending from the pool body 78, or it may only cover a portion of the outer circumference of the exhaust pipe 77. Furthermore, if the temperature adjustment unit 2 can be directly mounted to the exhaust pipe 77, the thermal conductivity detector 70 may not require mounting member 3. Figure 3 In the structure, the heat insulation part is composed of heat insulation component 79 and temperature adjustment part 2. The heat insulation component 79 and temperature adjustment part 2 are examples of the first heat insulation part and the second heat insulation part, respectively.

[0064] Furthermore, the same temperature adjustment unit as the temperature adjustment unit 2 can be installed on the pool body 78 instead of the heat insulation component 79. Here, the temperature adjustment unit installed on the pool body 78 functions as a heat preservation unit. If the protruding length of the exhaust pipe 77 protruding from the pool body 78 is set short to avoid the temperature of the sample gas discharged from the exhaust pipe 77 dropping below the liquefaction temperature, the temperature adjustment unit 2 may not need to be installed on the exhaust pipe 77.

[0065] (3) First variant of gas chromatograph

[0066] Figure 4This is a block diagram showing the structure of a first modified example of a gas chromatograph 100. Regarding the gas chromatograph 100 according to the first modified example, a description will be given... Figure 1 The gas chromatograph has 100 different points.

[0067] like Figure 4 As shown, in the gas chromatograph 100 involved in the first modified example, the thermal conductivity detector 70 is basically composed of two carrier introduction lines 75a and 75b, a sample introduction line 76, two hot wires F1 and F2, and a cell 78.

[0068] The carrier inlet pipes 75a and 75b are arranged to pass through the pool body 78. Both ends of each carrier inlet pipe 75a and 75b are led out to the outside of the pool body 78. The carrier inlet pipe 75a has an outlet 75d at one of its two ends. The carrier inlet pipe 75b has an outlet 75e at one of its two ends.

[0069] A hot wire F1 is housed inside one of the carrier inlet pipes 75a on the inside of the pool body 78, and a hot wire F2 is housed inside the other of the carrier inlet pipes 75b on the inside of the pool body 78.

[0070] Two carrier inlet pipes 75a and 75b are connected to the flow adjustment unit 50 via branch pipes. Thus, in the thermal conductivity detector 70, carrier gas is supplied from the flow adjustment unit 50 to the carrier inlet pipes 75a and 75b.

[0071] A gas inlet 75c is provided upstream of the specific heat filament F2 in the carrier inlet pipe 75b. The sample inlet pipe 76 is formed to extend from the gas inlet 75c to the outside of the pool body 78. A through hole is formed in the gas inlet 75c. Thus, the internal space of the carrier inlet pipe 75b is in communication with the internal space of the sample inlet pipe 76.

[0072] In this gas chromatograph 100, with carrier gas supplied from the flow adjustment unit 50 to the carrier inlet lines 75a and 75b respectively, sample gas is supplied from the column 40 to the sample inlet line 76. Thus, in the carrier inlet line 75a, the carrier gas, as a reference gas, passes around the hot filament F1. On the other hand, in the carrier inlet line 75b, the sample gas supplied from the sample inlet line 76 passes around the hot filament F2 together with the carrier gas.

[0073] Therefore, in the control unit 80, the thermal conductivity of the sample gas is measured based on the resistance value of the hot wire F1 when the reference gas passes around the hot wire F1 and the resistance value of the hot wire F2 when the sample gas passes around the hot wire F2.

[0074] In this example, the downstream end of the carrier inlet pipe 75b, which extends from the tank body 78, becomes the exhaust pipe 77. The carrier inlet pipe 75b and the sample inlet pipe 76 are examples of flow paths. The portion of the carrier inlet pipe 75b, excluding the exhaust pipe 77, is an example of the first part of the flow path, and the exhaust pipe 77 is an example of the second part of the flow path. The hot filament F2 is an example of a heating element.

[0075] Similarly, in this example, the exhaust pipe 77 is led out to the outside of the tank 78, therefore blockage due to sample gas is possible in the exhaust pipe 77. Therefore, in this example, an insulation component is installed in the exhaust pipe 77 to prevent the temperature of the discharged sample gas from dropping below its liquefaction temperature. Figure 4 In the structure, the heat insulation part is composed of heat insulation components 1 and 79. Heat insulation component 79 and heat insulation component 1 are examples of the first heat insulation part and the second heat insulation part, respectively.

[0076] The heat insulation element 1 can also be installed in a manner that covers only a portion of the outer periphery of the exhaust pipe 77, as in the examples of Figures 2(a) and 2(b). The heat insulation element 79, installed in the tank body 78, functions as a heat insulation component. The thermal conductivity detector 70 may not include the heat insulation element 1 if the exhaust pipe 77 is made short enough to prevent the temperature of the sample gas discharged from the exhaust pipe 77 from dropping below its liquefaction temperature. Alternatively, the heat insulation element 1 or heat insulation elements 1 and 79 may be replaced by... Figure 3 The temperature adjustment unit 2 is installed as a heat insulation unit in the exhaust pipe 77. The same applies in the second modification of the gas chromatograph 100 described later.

[0077] Furthermore, in this example, the downstream end of the carrier introduction pipe 75a, which extends from the tank body 78, also functions as an exhaust pipe. However, no sample gas is supplied to the carrier introduction pipe 75a, thus preventing blockage caused by the sample gas inside the carrier introduction pipe 75a. Therefore, no insulation is installed on the exhaust pipe corresponding to the carrier introduction pipe 75a.

[0078] (4) Second variation of gas chromatograph

[0079] Figure 5 This is a block diagram showing the structure of a second modified example of the gas chromatograph 100. Regarding the gas chromatograph 100 according to the second modified example, a description will be provided. Figure 1 The gas chromatograph has 100 different points.

[0080] like Figure 5 As shown, in the gas chromatograph 100 involved in the second modification, the thermal conductivity detector 70 is basically composed of a sample introduction line 76, a carrier introduction line 91, a gas flow line 92, two hot wires F1 and F2, and a cell 78.

[0081] The carrier inlet pipe 91 has an upstream end 91u and a downstream end 91d, and the gas flow pipe 92 has an upstream end 92u and a downstream end 92d. The gas flow pipe 92 has an outlet 92e at its downstream end 92d.

[0082] Regarding the carrier inlet pipe 91, its upstream end 91u is led out to the outside of the tank body 78, while the rest is housed inside the tank body 78. Similarly, regarding the gas flow pipe 92, its downstream end 92d is led out to the outside of the tank body 78, while the rest is housed inside the tank body 78. The upstream end 92u of the gas flow pipe 92 is connected to the downstream end 91d of the carrier inlet pipe 91, and is also connected to one end of the sample inlet pipe 76. The other end of the sample inlet pipe 76 is led out to the outside of the tank body 78. A hot wire F1 is housed inside the carrier inlet pipe 91, and a hot wire F2 is housed inside the gas flow pipe 92. Carrier gas is supplied from the flow adjustment unit 50 to the upstream end 91u of the carrier inlet pipe 91.

[0083] In this gas chromatograph 100, with carrier gas supplied from the flow adjustment unit 50 to the carrier inlet line 91, sample gas is supplied from the column 40 to the sample inlet line 76. Thus, in the carrier inlet line 91, the carrier gas, as a reference gas, passes around the hot filament F1. Meanwhile, in the gas flow line 92, the sample gas supplied from the sample inlet line 76 and the carrier gas supplied from the carrier inlet line 91 pass together around the hot filament F2.

[0084] Therefore, in the control unit 80, the thermal conductivity of the sample gas is measured based on the resistance value of the hot wire F1 when the reference gas passes around the hot wire F1 and the resistance value of the hot wire F2 when the sample gas passes around the hot wire F2.

[0085] In this example, the downstream end 92d of the gas flow pipe 92, extending from the tank body 78, becomes the exhaust pipe 77. The sample inlet pipe 76 and the carrier inlet pipe 91 are examples of flow paths. The portion of the carrier inlet pipe 91, excluding the exhaust pipe 77, is an example of the first part of the flow path, and the exhaust pipe 77 is an example of the second part of the flow path. Hot wires F1 and F2 are examples of heating elements.

[0086] Similarly, in this example, the exhaust pipe 77 is led out to the outside of the tank 78, therefore blockage due to sample gas is possible in the exhaust pipe 77. Therefore, in this example, an insulation component is installed in the exhaust pipe 77 to prevent the temperature of the discharged sample gas from dropping below its liquefaction temperature. Figure 5 In the structure, the heat insulation part is composed of heat insulation components 1 and 79. Heat insulation component 79 and heat insulation component 1 are examples of the first heat insulation part and the second heat insulation part, respectively.

[0087] (5) Effect

[0088] In the thermal conductivity detector 70 of this embodiment, the upstream portion of the flow path is housed in a cell 78, and the exhaust pipe 77 of the downstream portion of the flow path is located outside the cell 78. Hot wires F, F1, and F2, used to detect the thermal conductivity of the sample gas, are housed in the upstream portion of the flow path. The sample gas is guided through the flow path to the exhaust pipe 77. The flow path is insulated using heat-insulating components such as the heat insulation member 1, the temperature adjustment unit 2, or the heat insulation member 79 to prevent the temperature of the sample gas passing through the exhaust pipe 77 from dropping below its liquefaction temperature.

[0089] This structure prevents the high-temperature sample gas from being cooled and condensed or solidified in the exhaust pipe 77. Therefore, flow path blockage is prevented, eliminating the need to replace the thermal conductivity detector 70 in the gas chromatograph 100. Consequently, the operating cost of the gas chromatograph 100 is reduced.

[0090] [2] Second implementation method

[0091] (1) Overview of the structure of a gas chromatograph

[0092] Regarding the gas chromatograph according to the second embodiment, the differences from the gas chromatograph 100 according to the first embodiment will be explained. Figure 6 This is a block diagram illustrating the structure of the gas chromatograph according to the second embodiment. Figure 6 As shown, the thermal conductivity detector 70 in this embodiment does not include the heat insulation member 1. Furthermore, the exhaust pipe 77 of the thermal conductivity detector 70 includes a fixing part 77a and a mounting part 77b.

[0093] Furthermore, regarding the gas chromatograph 100 involved in this embodiment, the thermal conductivity detector 70 does not include the heat insulation component 1, and the exhaust pipe 77 includes a fixing part 77a and a mounting part 77b. Apart from these, it may have components similar to... Figure 4 or Figure 5 It has the same structure as the gas chromatograph 100.

[0094] One end of the fixing part 77a is connected to the gas outlet 74a. In this example, the fixing part 77a is fixed relative to the gas outlet 74a and cannot be installed or removed. The other end of the fixing part 77a extends to the outside of the pool body 78. In this example, the other end of the fixing part 77a does not protrude outward from the heat insulation member 79. The loading and unloading part 77b is connected to the other end of the fixing part 77a in a manner that allows it to be installed or unloaded relative to the fixing part 77a. The sample gas whose thermal conductivity is measured in the thermal conductivity detector 70 is discharged to the outside of the thermal conductivity detector 70 in sequence through the fixing part 77a and the loading and unloading part 77b.

[0095] (2) Example of exhaust pipe deformation

[0096] exist Figure 6In the example, the other end of the fixing part 77a does not protrude from the heat insulation member 79 to the outside, but the present invention is not limited thereto. Figure 7 This is a schematic diagram showing a first modified example of the exhaust pipe 77. (As shown) Figure 7 As shown, the other end of the fixing part 77a may also protrude slightly outward from the heat insulation member 79. Here, the length of the portion of the fixing part 77a protruding from the heat insulation member 79 is limited to a length that prevents the temperature of the sample gas discharged from the fixing part 77a from dropping below the liquefaction temperature. In this case, the sample gas passing through the fixing part 77a will not liquefy but will be guided to the loading and unloading part 77b, and after passing through the loading and unloading part 77b, it will be discharged to the outside of the thermal conductivity detector 70.

[0097] exist Figure 6 and Figure 7 In the example, the exhaust pipe 77 includes a fixing part 77a, but the present invention is not limited thereto. Figure 8 This is a schematic diagram showing a second modified example of the exhaust pipe 77. (As shown...) Figure 8 As shown, the exhaust pipe 77 does not include the fixing part 77a, but only the loading and unloading part 77b. The loading and unloading part 77b is connected to the gas outlet part 74a in a detachable manner. The sample gas whose thermal conductivity is measured in the thermal conductivity detector 70 is discharged to the outside of the thermal conductivity detector 70 through the loading and unloading part 77b.

[0098] (3) Effect

[0099] In the thermal conductivity detector 70 of this embodiment, the upstream portion of the flow path is housed in a cell 78, and the exhaust pipe 77 of the downstream portion of the flow path is located outside the cell 78. Hot wires F, F1, and F2 used to detect the thermal conductivity of the sample gas are housed in the upstream portion of the flow path. The sample gas is guided to the exhaust pipe 77 through the flow path. At least a portion of the exhaust pipe 77, including its downstream end, includes a loading / unloading section 77b, which is configured to be loadable and unloadable relative to other portions of the flow path, such as the fixed section 77a or the fourth pipe 74.

[0100] According to this structure, even if the downstream portion of the exhaust pipe 77 becomes blocked, the thermal conductivity detector 70 can continue to be used by replacing at least the loading / unloading portion 77b, including the downstream end, in the exhaust pipe 77. Therefore, it is not necessary to replace the entire thermal conductivity detector 70. This reduces the operating cost of the gas chromatograph 100. In addition, it shortens the downtime of the gas chromatograph 100.

Claims

1. A thermal conductivity detector, used in a gas chromatograph, comprising: A flow path having a first portion and a second portion located downstream of the first portion for guiding sample gas through the first portion and the second portion to the outlet of the second portion; A housing that contains the first part; A heating device is housed within the housing; A heating element, which is housed in the first part, is used to detect the thermal conductivity of the sample gas; as well as The insulation section keeps the flow path warm to prevent the temperature of the sample gas passing through the second section from dropping below its liquefaction temperature. The housing is provided with a heat insulation component, at least a portion of the second part is located outside the heat insulation component, and the heat insulation part is provided on the portion of the second part outside the heat insulation component.

2. The thermal conductivity detector according to claim 1, characterized in that, The heat insulation section is installed on the second part to prevent the temperature of the sample gas passing through the second part from dropping below the liquefaction temperature of the sample gas.

3. The thermal conductivity detector according to claim 2, characterized in that, The length of the second portion outside the insulation is set to prevent the temperature of the sample gas discharged from the second portion from dropping below the liquefaction temperature.

4. The thermal conductivity detector according to any one of claims 1 to 3, characterized in that, The insulation section includes a temperature adjustment section for adjusting the temperature of the sample gas.

5. A gas chromatograph, comprising: The sample vaporization section generates sample gas by vaporizing the sample. A column, used to separate the components of the sample gas generated by the sample vaporization section; and The thermal conductivity detector according to any one of claims 1 to 3, in, The thermal conductivity detector measures the thermal conductivity of the sample gas separated from each component using the column.

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