Column oven and gas chromatograph

Abstract

The present invention relates to a column oven and a gas chromatograph. The column oven (2) comprises: an inner shell (10) having an inner space (11) formed therein, the inner space being used to accommodate a separation column (4) for the gas chromatograph and to regulate the temperature of the separation column (4); a temperature regulating device (12) disposed in the inner space (11) for regulating the temperature of the inner space (11); and a heat insulating material layer (14) surrounding the outer peripheral surface of the inner shell (10) and being composed of a fibrous raw material, the heat insulating material layer (14) comprising: a first layer (18) having a first volume density (ρ1); and a second layer (20) surrounding the outer side of the first layer (18) and having a second volume density (ρ2) lower than the first volume density (ρ1).

Description

Technical Field

[0001] The present invention relates to a column oven and a gas chromatograph equipped with the column oven. Background Art

[0002] In a gas chromatograph, the separation column used to separate the components in a sample gas is typically housed in a column oven. The temperature of the separation column is controlled to a set temperature by increasing or decreasing the temperature within the column oven. The column oven houses the separation column, and the interior space is surrounded by a heat-insulating material, insulating the interior space from the outside (see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-162972 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] To precisely control the temperature within a column oven, it is important to improve the thermal insulation of the interior space. Generally speaking, increasing the volume of insulating material improves insulation performance. Therefore, increasing the volume of insulating material surrounding the interior space of a column oven can improve the insulation. However, this also increases the thermal capacity of the insulating material, which increases the time required for the insulating material to cool naturally when the temperature within the column oven is desired to be lowered.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to improve the cooling efficiency of the internal space of a column oven while ensuring the thermal insulation of the internal space.

[0009] Solutions for solving problems

[0010] The thermal conductivity λ [W / (m·K)] of a thermal insulation material can be approximated using the thermal conductivity of a solid, the thermal conductivity contributed by radiation, and the thermal conductivity of a gas (see Takahiro Omura et al., Kyushu University Institute for Functional Materials Science, Vol. 16, pp. 13-17, 2002, for a study on the effective thermal conductivity of fibrous thermal insulation materials). Specifically, the thermal conductivity λ of a thermal insulation material can be expressed using the following equation (1).

[0011] λ=Aρ+(B / ρ)T 3 +C (1)

[0012] Here, A, B, and C are coefficients obtained experimentally, and ρ is the bulk density of the thermal insulation material [kg / m 3], T is the absolute temperature [K]. The first term on the right side of this formula is the thermal conductivity of the solid, the second term is the thermal conductivity contributed by radiation, and the third term is the thermal conductivity of the gas. According to the above formula (1), in high temperature areas (for example, above 300°C), radiation contributes more to heat conduction, and the greater the volume density of the thermal insulation material, the smaller the thermal conductivity generated by radiation. In other words, the greater the volume density of the thermal insulation material, the higher the thermal insulation performance in the high temperature area. Conversely, in the low temperature area, the volume density ρ contributes more to the thermal conductivity.

[0013] In addition, according to the law of conservation of heat, the amount of heat Q[J] stored in an object can be expressed by the following formula (2).

[0014] Q=ρVcΔT (2)

[0015] V is the volume of the insulation material [m 3 ], c is the specific heat [J / kg·K]. According to this formula (2), when comparing thermal insulation materials of the same volume, the lower the bulk density of the thermal insulation material, the smaller the amount of stored heat, that is, the smaller the heat capacity.

[0016] The present invention utilizes the aforementioned features to improve the thermal insulation performance and cooling efficiency within the column oven. Specifically, the column oven of the present invention comprises: an inner housing having an internal space formed therein for accommodating a separation column for a gas chromatograph and regulating the temperature of the separation column; a temperature control device disposed within the internal space for regulating the temperature of the internal space; and a heat-insulating material layer surrounding the outer circumference of the inner housing and composed of a fibrous raw material. The heat-insulating material layer includes: a first layer having a first bulk density; and a second layer surrounding the outer side of the first layer and having a second bulk density lower than the first bulk density.

[0017] The gas chromatograph of the present invention comprises: a sample vaporization section having a sample injection port for vaporizing the sample injected from the sample injection port to generate a sample gas; a separation column for separating the components in the sample gas generated in the sample vaporization section from each other, having an inlet and an outlet, the inlet being fluidically connected to the sample vaporization section; a detector connected to the outlet of the separation column for detecting the components separated from each other in the separation column; and a column oven of the present invention having an internal space for accommodating the separation column and adjusting the temperature of the separation column.

[0018] Effects of the Invention

[0019] In the column oven of the present invention, a first layer having a higher volume density (first volume density) is used in the high-temperature region near the inner shell to effectively block heat generated by radiation from the inner shell. Simultaneously, a second layer having a lower volume density (second volume density) is placed in the lower-temperature region outside the first layer. This ensures the volume of the insulation layer, ensuring high thermal insulation performance and suppressing the increase in heat capacity. This ensures that the thermal insulation of the interior space of the column oven is maintained while improving the cooling efficiency of the interior space.

[0020] In the gas chromatograph of the present invention, since the column oven of the present invention is used, the time required for heating and cooling the separation column can be shortened, thereby improving the analysis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a cross-sectional view schematically showing the structure of an embodiment of a gas chromatograph.

[0022] Figure 2 It is a cross-sectional view for explaining the structure of the heat insulating layer of the column oven of this embodiment.

[0023] Description of Reference Numerals

[0024] 1. Gas chromatograph; 2. Column oven; 4. Separation column; 6. Sample vaporization unit; 8. Detector; 10. Inner shell; 12. Temperature control device; 14. Insulation material layer; 16. Outer shell; 18. First layer; 20. Second layer. DETAILED DESCRIPTION

[0025] An embodiment of the column oven and the gas chromatograph of the present invention will be described below with reference to the accompanying drawings.

[0026] exist Figure 1 Schematically shows the structure of the gas chromatograph 1.

[0027] The gas chromatograph 1 includes a column oven 2, a separation column 4, a sample vaporization unit 6, and a detector 8. The separation column 4 is housed in an internal space 11 of the column oven 2. A temperature control device 12 is provided in the internal space 11 of the column oven 2 for regulating the temperature of the internal space 11. The temperature control device 12 includes, for example, a heater, a Peltier element, a fan, and the like.

[0028] The sample vaporizer 6 and detector 8 are mounted on top of the column oven 2. The separation column 4 has an inlet at one end and an outlet at the other. The inlet is connected to the sample vaporizer 6, and the outlet is connected to the detector 8. The sample vaporizer 6 has a sample injection port 7 at its top, which vaporizes the sample injected through the sample injection port 7 to generate sample gas. The sample gas generated in the sample vaporizer 6 is introduced into the separation column 4, where the components in the sample gas are separated. The detector 8 detects the components separated in the separation column 4.

[0029] The column oven 2 includes an inner housing 10 having an inner space 11 formed therein, a heat insulating layer 14 surrounding the outer peripheral surface of the inner housing 10, and an outer housing 16 further surrounding the outer side of the heat insulating layer 14. In other words, the wall surface of the column oven 2 is composed of the inner housing 10, the heat insulating layer 14, and the outer housing 16 from the inner side (see FIG. Figure 2 The top wall of the column oven 2 is provided with through holes for the sample vaporizer 6 and the detector 8 to pass through. The sample vaporizer 6 and the detector 8 are fixed to the outer housing 16 in a state of passing through the top of the column oven 2 .

[0030] The thermal insulation layer 14 between the inner shell 10 and the outer shell 16 of the column oven 2 is formed from a fibrous material such as glass wool or rock wool. The thermal insulation layer 14 includes a first layer 18 and a second layer 20. The first layer 18 covers the outer circumference of the inner shell 10, and the second layer 20 covers the outer circumference of the first layer 18.

[0031] exist Figure 2 The inner cross section of the wall of the column oven 2 is shown in FIG.

[0032] The first layer 18 of the thermal insulating material layer 14 is located in a region close to the inner shell 10. This region reaches a high temperature when the temperature of the separation column 4 is raised to a high temperature (e.g., 300°C or higher). Meanwhile, the second layer 20 of the thermal insulating material layer 14 is located in a region farther from the inner shell 10. This region is kept cooler than the region where the first layer 18 is located, due to the presence of the first layer 18 between the second layer 20 and the inner shell 10.

[0033] The first layer 18 and the second layer 20 have different volume densities ρ1 and ρ2, respectively. The volume density ρ1 of the first layer 18 is higher than the volume density ρ2 of the second layer 20. As an example, the volume density ρ1 of the first layer is at least twice the volume density ρ2 of the second layer 20. In addition, the thickness L2 of the second layer 20 is greater than the thickness L1 of the first layer. As an example, the thickness L2 of the second layer 20 is at least twice the thickness L1 of the first layer.

[0034] As mentioned above, radiation contributes significantly to heat conduction in high-temperature regions (e.g., above 300°C), and the greater the bulk density of the insulation material, the lower the thermal conductivity due to radiation. Therefore, if the sole objective is to improve the thermal insulation performance of interior space 11, it is sufficient to cover the outer circumference of inner shell 10 with a thicker layer of insulation material having a higher bulk density. In other words, forming insulation layer 14 solely from first layer 18 having a higher bulk density is sufficient. However, this increases the heat capacity of insulation layer 14, requiring a longer time to cool interior space 11.

[0035] In this embodiment, the first layer 18 having a higher volume density ρ1 is arranged only in the region where high temperatures are reached, and the second layer 20 having a lower volume density ρ2 is arranged in the lower temperature region outside it. In the low temperature region, radiation contributes less to heat conduction than in the high temperature region. Therefore, even if the volume density ρ2 of the heat insulating material layer (second layer 20) arranged in the low temperature region is lower than the volume density ρ1 of the heat insulating material layer (first layer 18) arranged in the high temperature region, a sufficient heat insulating effect can be obtained by ensuring a certain thickness L2 of the second layer 20 (for example, more than twice L1). In addition, the second layer 20 has a smaller heat capacity due to its lower volume density ρ2, and thus the heat capacity of the entire heat insulating material layer 14 can be reduced. In particular, by designing the second layer 20 to occupy a majority of the volume of the heat insulating material layer 14 (for example, more than 60%), a heat insulating material layer 14 with high heat insulating performance and low heat capacity can be achieved.

[0036] Furthermore, the heat insulating material layer 14 does not necessarily need to completely cover the outer peripheral surface of the inner shell 10, and a portion of the outer peripheral surface of the inner shell 10 may not be covered by the heat insulating material layer 14. Furthermore, cloth, foil, or the like may be interposed between the outer peripheral surface of the inner shell 10 and the first layer 18, between the first layer 18 and the second layer 20, and between the second layer 20 and the outer shell 16.

[0037] The embodiment described above is merely one example of the embodiment of the column oven and gas chromatograph of the present invention. One embodiment of the column oven and gas chromatograph of the present invention is as follows.

[0038] In one embodiment of the column oven of the present invention, the column oven comprises: an inner shell having an internal space formed on its inner side, the internal space being used to accommodate a separation column for a gas chromatograph and to regulate the temperature of the separation column; a temperature regulating device being arranged in the internal space and being used to regulate the temperature of the internal space; and a heat-insulating material layer surrounding the outer peripheral surface of the inner shell and being composed of a fibrous raw material, the heat-insulating material layer comprising: a first layer having a first volume density; and a second layer surrounding the outer side of the first layer and having a second volume density lower than the first volume density.

[0039] In one of the aforementioned embodiments, the second layer of the thermal insulation material layer may be thicker than the first layer. Since the second layer is positioned in a lower temperature region than the first layer, ensuring a certain thickness of the second layer can achieve a sufficient thermal insulation effect. While increasing the thickness of the second layer increases the overall volume of the thermal insulation material layer, the lower volume density of the second layer compared to the first layer suppresses the increase in the overall heat capacity of the thermal insulation material layer, thereby shortening the time required to cool the interior of the column oven.

[0040] In one embodiment of the gas chromatograph of the present invention, the gas chromatograph comprises: a sample vaporization section having a sample injection port for vaporizing the sample injected from the sample injection port to generate a sample gas; a separation column for separating the components in the sample gas generated in the sample vaporization section from each other, having an inlet and an outlet, the inlet being fluidically connected to the sample vaporization section; a detector connected to the outlet of the separation column for detecting the components separated from each other in the separation column; and the above-mentioned column oven having an internal space for accommodating the separation column and adjusting the temperature of the separation column.

Claims

1. A column oven, wherein: The column oven has: An inner shell having an inner space formed therein for accommodating a separation column for a gas chromatograph and regulating the temperature of the separation column; a temperature regulating device, which is provided in the internal space and is used to regulate the temperature of the internal space; as well as a heat-insulating material layer surrounding the outer peripheral surface of the inner shell and made of a fibrous raw material, The thermal insulation material layer includes: a first layer having a first volume density; and a second layer surrounding the outer side of the first layer and having a second volume density lower than the first volume density.

2. The column oven according to claim 1, wherein The second layer of the heat-insulating material layer has a thickness greater than that of the first layer.

3. A gas chromatograph, wherein: The gas chromatograph has: a sample vaporizing portion having a sample injection port and vaporizing a sample injected from the sample injection port to generate a sample gas; a separation column for separating components in the sample gas generated in the sample vaporization section from each other, the separation column having an inlet and an outlet, the inlet being fluidically connected to the sample vaporization section; a detector connected to the outlet of the separation column and configured to detect components separated from each other in the separation column; as well as The column oven according to claim 1 or 2, comprising an internal space for accommodating the separation column and regulating the temperature of the separation column.

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