JP2012237600A - Gas chromatograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas chromatograph apparatus capable of controlling the flow rate of a carrier gas and controlling the pressure in a sample introduction part without using an expensive differential pressure sensor.
A gas chromatograph apparatus 1 including a sample introduction unit 20, a carrier gas supply channel 10, a column 3, a split channel 40, and a control unit 50, wherein a flow disposed in the carrier gas supply channel 10 is provided. A path resistance 11; a control valve 14 provided on the upstream side of the flow path resistance 11; the first pressure detection unit 12 for detecting the pressure on the upstream side of the flow path resistance 11; A second pressure detector 13 for detecting the pressure on the downstream side, and a discharge valve 41 with an adjustable opening provided in the split flow path 40, and the controller 50 includes the first pressure detector 12 and the first pressure detector 12. An operation is performed based on a signal from the two-pressure detection unit 13, and the opening degree of the control valve 14 and the opening degree of the discharge valve 41 are controlled based on the calculation result.
[Selection] Figure 1

Description

  The present invention relates to a gas chromatograph device, and in particular, controls the flow rate of a carrier gas to an arbitrary set value by adjusting the opening of a control valve, and adjusts the pressure in a sample introduction unit by adjusting the opening of a discharge valve. The present invention relates to a gas chromatograph apparatus that controls an arbitrary set value.

  In the gas chromatograph apparatus, a liquid sample is injected into a sample vaporizing chamber, and the vaporized sample is placed on a carrier gas and introduced into a column. At this time, the flow rate of the carrier gas supplied to the sample introduction part needs to be precisely controlled in order to make the quantitative and qualitative analysis accurate. Therefore, by adjusting the opening of the control proportional valve (control valve) in the carrier gas supply channel while measuring the flow rate of the carrier gas in the carrier gas supply channel using the differential pressure sensor and the pressure sensor. (See, for example, Patent Document 1).

  FIG. 2 is a schematic configuration diagram illustrating an example of a conventional gas chromatograph apparatus. The gas chromatograph apparatus 101 includes a sample introduction chamber 20 for injecting a sample and vaporizing the sample, a carrier gas supply channel 110, a column 3, a detector 4, a split channel 40, a purge channel 30, and a control. Unit 150.

  A silicon rubber septum (not shown) is fitted into the head opening of the sample vaporizing chamber 20, and the inside of the sample vaporizing chamber 20 has a carrier gas supply channel 110 for introducing a carrier gas. An outlet end, an inlet end of a purge flow path 30 for discharging an undesired component generated by a silicone rubber septum (not shown), and an excess vaporized sample together with a carrier gas to the outside The split channel 40 is connected to the inlet end of the column 3 and the inlet end of the column 3. In such a sample vaporization chamber 20, when analyzing, an analyst may drop the liquid sample into the sample vaporization chamber 20 by inserting the needle of the microsyringe 5 containing the liquid sample into the septum. It can be done. Since the septum has elasticity, the hole opened when the needle is inserted is immediately closed when the needle is removed.

In the carrier gas supply channel 110, in order from the upstream side, the cylinder 2 in which the carrier gas is sealed, the laminar flow tube (channel resistance) 11 that causes an appropriate pressure drop in the carrier gas, and the flow rate of the carrier gas are set. A control proportional valve 114 capable of adjusting the opening for adjustment is disposed. Then, a differential pressure sensor 113 that detects a differential pressure ΔP between the pressure upstream of the laminar flow tube (channel resistance) 11 and the pressure downstream thereof, and the pressure P upstream of the laminar flow tube (channel resistance) 11 ₁ is provided.

Here, the flow rate F of the carrier gas flowing through the carrier gas supply channel 110 can be calculated by the following Naviestokes equation (1).
F = (P ₁ ² −P ₂ ² ) / R (1)
P ₁ is the pressure upstream of the channel resistance,
P ₂ is the pressure downstream of the channel resistance,
R is the channel resistance.

Further, the channel resistance is represented by the following formula (2).
R = ((256 × L) / (60π × d4)) × ((T × μ _T ) / (T0 / P0)) (2)
L is the length of the laminar flow tube,
d is the inner diameter of the laminar flow tube,
T is the fluid temperature (= temperature of the laminar flow tube),
μ _T is the viscosity coefficient of the fluid at temperature T,
T0 is the standard temperature (usually 298K),
P0 is a standard pressure (usually 101.35 kPa).

Further, when a liquid sample is injected into the sample vaporizing chamber 20 during analysis, the volume of the injected sample is rapidly expanded due to vaporization. Therefore, the pressure P ₃ of the sample vaporizing chamber 20 is rapidly increased. Therefore, the purge flow path 30 is provided with a pressure sensor 131 for detecting the pressure P ₃ of the purge flow path 30, and the split flow path 40 is provided with an openable / closable discharge valve 141. Thus, when the pressure P ₃ of the sample vaporizing chamber 20 abruptly increases, by opening the discharge valve 141, the carrier gas and sample a percentage of the sample vaporizing chamber 20 through the split flow channel 40 outside To escape.

The control unit 150 is embodied by a personal computer, includes a CPU 151 and a memory 54, and further includes an input device 52 having a keyboard, a mouse, and the like, and setting contents (desired flow rate F _SET , desired column linear velocity, desired sample, etc. A display device 53 for displaying the vaporization chamber pressure _{P3SET and the} like and the analysis result is connected. The operation of the control proportional valve 114 and the signal P from the pressure sensor 131 are determined by the CPU 151 on the basis of the setting content input by the input device 52, the signal ΔP from the differential pressure sensor 113 and the signal P ₁ from the pressure sensor 112. ₃ , the operation of the discharge valve 141 is comprehensively controlled. The memory 54 stores the formula (1).

According to such a gas chromatograph apparatus 101, an analyst inputs a desired flow rate F _SET or the like to the CPU 151 using the input device 52 before analysis. The CPU 151 always obtains the differential pressure ΔP _SET corresponding to the desired flow rate F _SET by substituting the signal P ₁ from the pressure sensor 112 into the equation (1) when analyzing, and obtains the differential pressure ΔP _SET from the differential pressure sensor 113. A control signal for adjusting the opening of the control proportional valve 114 is sent to the control proportional valve 114 so that the signal ΔP becomes the differential pressure ΔP _SET . As a result, the carrier gas whose flow rate F is adjusted by the CPU 151 is introduced into the column 3 and then reaches the detector 4. At this time, if a liquid sample is injected into the sample vaporization chamber 20, the vaporized sample is placed on the carrier gas and introduced into the column 3.

Japanese Patent Laid-Open No. 10-300737

However, in the gas chromatograph apparatus 101 as described above, the differential pressure sensor 113 that detects the differential pressure ΔP between the upstream pressure and the downstream pressure of the laminar flow tube (flow path resistance) 11, and the laminar flow tube (flow) A pressure sensor 112 for detecting the pressure P ₁ upstream of the path resistance) 11 and a pressure sensor 131 for detecting the pressure P ₃ in the sample vaporizing chamber 20 are provided. Since each sensor is a differential pressure sensor, it is very expensive.
Therefore, an object of the present invention is to provide a gas chromatograph apparatus that can control the flow rate of the carrier gas and the pressure in the sample introduction part without using an expensive differential pressure sensor.

  In order to solve the above problems, the gas chromatograph of the present invention includes a sample introduction part for injecting a sample and vaporizing the sample, a carrier gas supply channel connected to the sample introduction part, and the sample introduction part A column connected to the sample introduction unit, a split channel connected to the sample introduction unit, a flow rate of the carrier gas flowing through the column from the carrier gas supply channel through the sample introduction unit, and the inside of the sample introduction unit A gas chromatograph apparatus comprising a control unit for controlling pressure, wherein the flow resistance is arranged in the carrier gas supply flow path, and the control valve capable of adjusting the opening provided on the upstream side of the flow resistance. A first pressure detection unit that detects a pressure upstream of the flow path resistance, a second pressure detection unit that detects a pressure downstream of the flow path resistance, and the split flow path A discharge valve capable of adjusting the degree, and the control unit performs a calculation based on signals from the first pressure detection unit and the second pressure detection unit, and based on a calculation result, the opening degree of the control valve and the discharge The valve opening is controlled.

According to the gas chromatograph apparatus of the present invention, the flow path resistance is provided on the downstream side of the control valve. Although the arrangement is interchanged with that of the conventional gas chromatograph apparatus, the control valve and the flow path resistance are connected in series and the same carrier gas flows, so that the formula (1) is established. In addition, a first pressure detection unit that detects a pressure upstream of the channel resistance and a second pressure detection unit that detects a pressure downstream of the channel resistance are provided. Thus, the control unit can always obtain the pressure P _1SET corresponding to the desired flow rate F _SET by substituting the signal P ₂ from the second pressure detection unit into the equation (1) when analyzing. . As a result, the flow rate of the carrier gas can be controlled to an arbitrary set value F _SET by adjusting the opening of the control valve so that the signal P ₁ from the first pressure detection unit becomes the pressure P _{1 SET.} .

Further, the downstream side of the channel resistance is directly connected to the sample introduction part. That is, since there is no element that causes a pressure drop between the flow path resistance and the sample introduction part, the pressure P ₂ on the downstream side of the flow path resistance becomes equal to the pressure in the sample introduction part. Therefore, the control unit is always in analyzing, by obtaining a signal P ₂ from the second pressure detecting unit, by adjusting the degree of opening of the discharge valve, the pressure in the sample inlet of any set value P _2SET can be controlled.

  As described above, according to the gas chromatograph apparatus of the present invention, the flow rate F of the carrier gas can be controlled and the pressure P in the sample introduction part can be controlled without using an expensive differential pressure sensor.

The schematic block diagram which shows an example of the gas chromatograph apparatus which concerns on this invention. The schematic block diagram which shows an example of the conventional gas chromatograph apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and it goes without saying that various aspects are included without departing from the spirit of the present invention.

FIG. 1 is a schematic configuration diagram showing an example of a gas chromatograph apparatus according to the present invention. In addition, the same code | symbol is attached | subjected about the thing similar to the conventional gas chromatograph apparatus 101 mentioned above.
The gas chromatograph apparatus 1 includes a sample introduction chamber 20 for injecting a sample and vaporizing the sample, a carrier gas supply channel 10, a column 3, a detector 4, a split channel 40, a purge channel 30, and a control. Part 50.

The carrier gas supply flow path 10 includes, in order from the upstream side, a cylinder 2 filled with a carrier gas, a control proportional valve (control valve) 14 with an adjustable opening for adjusting the flow rate of the carrier gas, and a carrier gas. And a laminar flow tube (flow path resistance) 11 that generates an appropriate pressure drop. The first pressure sensor 12 detects the pressure P ₁ upstream of the laminar flow tube (channel resistance) 11 and the second pressure detects the pressure P ₂ downstream of the laminar flow tube (channel resistance) 11. A sensor 13 is provided.

The split flow path 40 is provided with a discharge proportional valve (discharge valve) 41 whose opening degree can be adjusted. Thus, when the pressure P ₂ in the sample vaporization chamber 20 is rapidly increased, by adjusting the degree of opening of the exhaust proportional valve 41, a split flow channel 40 a percentage carrier gas and the sample of the sample vaporizing chamber 20 It is possible to escape to the outside through.
Incidentally, the purge flow path 30 of the gas chromatograph apparatus 1 is not provided with a pressure sensor for detecting the pressure P ₃ of the purge flow path 30.

The control unit 50 is embodied by a personal computer, includes a CPU 51 and a memory 54, and further includes an input device 52 having a keyboard, a mouse, and the like, and setting contents (desired flow rate F _SET , desired column linear velocity, desired sample, etc. A display device 53 for displaying the vaporization chamber pressure _{P2SET and the} like and displaying the analysis result is connected. The CPU 51, based on the signal P ₁ from setting a first pressure sensor 12 that is input by the input device 52 and the signal P ₂ from the second pressure sensor 13, the operation and the discharge proportional valve 41 control the proportional valve 14 Are controlled in an integrated manner. The memory 54 stores the formula (1).

According to such a gas chromatograph apparatus 1, the analyst inputs a desired flow rate F _SET or the like to the CPU 51 using the input device 52 before analysis. The CPU 51 always _obtains the pressure P _1SET corresponding to the desired flow rate F _SET by substituting the signal P ₂ from the second pressure sensor 13 into the equation (1) when analyzing, and from the first pressure sensor 12. The control signal for adjusting the opening degree of the control proportional valve 14 is sent to the control proportional valve 14 so that the signal P ₁ becomes the pressure P _1SET . As a result, the carrier gas whose flow rate F is adjusted by the CPU 51 is introduced into the column 3 and then reaches the detector 4. At this time, if a liquid sample is injected into the sample vaporization chamber 20, the vaporized sample is placed on the carrier gas and introduced into the column 3.

Further, CPU 51 is always in analyzing, by obtaining a signal _{P 2} from the second pressure sensor 13, so that the signal _{P 2} from the second pressure sensor 13 is a pressure _{P 2SET,} exhaust proportional valve 41 A control signal for adjusting the degree of opening is sent to the discharge proportional valve 41. Thus, when the pressure P ₂ in the sample vaporization chamber 20 abruptly increases, or can be released to the outside through the split flow channel 40 a carrier gas and sample a percentage of the sample vaporizing chamber 20, a sample vaporizing when the pressure P ₂ in the chamber 20 is low, the carrier gas and sample in the sample vaporizing chamber 20 or can reduce the amount released to the outside through the split flow channel 40.

  As described above, according to the gas chromatograph apparatus 1 of the present invention, the flow rate F of the carrier gas can be controlled and the pressure P in the sample introduction chamber 20 can be controlled without using an expensive differential pressure sensor.

  The present invention can be used for a gas chromatograph apparatus.

1: Gas chromatograph device 3: Column 10: Carrier gas supply channel 11: Laminar flow tube (channel resistance)
12: First pressure sensor (first pressure detector)
13: Second pressure sensor (second pressure detector)
14: Control proportional valve (control valve)
20: Sample introduction chamber 40: Split flow path 41: Discharge proportional valve (discharge valve)
50: Control unit

Claims (1)

A sample introduction part for injecting a sample and vaporizing the sample;
A carrier gas supply channel connected to the sample introduction unit;
A column connected to the sample introduction part;
A split channel connected to the sample introduction part;
A gas chromatograph apparatus comprising a control unit for controlling the flow rate of the carrier gas flowing through the column from the carrier gas supply channel through the sample introduction unit, and for controlling the pressure in the sample introduction unit,
A channel resistance disposed in the carrier gas supply channel;
A control valve having an adjustable opening provided on the upstream side of the flow path resistance;
A first pressure detector that detects a pressure upstream of the flow path resistance;
A second pressure detector for detecting the pressure downstream of the flow path resistance;
A discharge valve with adjustable opening, provided in the split flow path,
The control unit performs a calculation based on signals from the first pressure detection unit and the second pressure detection unit, and controls the opening of the control valve and the opening of the discharge valve according to a calculation result. Gas chromatograph device.

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