JPH07294504A - Gas chromatograph and carrier gas flow rate control method thereof - Google Patents

Abstract

PURPOSE:To achieve the cost reduction of apparatus of a gas chromatograph by enabling the measurement and control of the flow rates of a plurality of carrier gas passages to be performed and making the number of carrier gas flowmeters installed one. CONSTITUTION:When the flow rate of the carrier gas in either one of carrier gas passages 10, 20 is controlled by either one of carrier gas flow rate controllers 11, 12, pressure fluctuations are generated in the controlled passage and the pressure value of carrier gas is inputted to a passage judging device 3 from a pressure sensor 12 or 22 and it is judged that which of the flow passages pressure fluctuations are generated in, that is, in which of the passages a flow rate is controlled, by a passage judging device 3 and the controlled carrier gas passage is automatically selected by a passage changeover device 1. The flow rate of the carrier gas of the selected passage is controlled while being measured by a carrier gas flowmeter 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph for detecting a component of a sample by separating it with a carrier gas, and more particularly to a gas chromatograph having a plurality of carrier gas channels and a method for adjusting the carrier gas flow rate thereof.

[0002]

2. Description of the Related Art In a gas chromatograph in which components of a sample in a column are separated by a carrier gas and detected, the flow rate of the carrier gas flowing in the column is a major factor affecting the separation condition of the components in the sample, and It is adjusted and set before using the device. Some gas chromatographs have a plurality of carrier gas flow paths in one device in order to improve analysis efficiency. In this case, in order to adjust the flow rate of each carrier gas, each flow rate is adjusted. Measurement is required. In a gas chromatograph equipped with a plurality of such carrier gas channels,
Conventionally, a carrier gas flow meter is provided for each carrier gas flow path, and each flow rate is adjusted while measuring each flow rate.

As another conventional technique relating to a gas chromatograph, as described in JP-A-55-96451, the supply of a plurality of sample gases is automatically switched according to a program registered in advance. There is one that analyzes the components of these multiple sample gases.

[0004]

Recently, it has become mainstream to use a digital type gas flow meter as the carrier gas flow meter, which can measure the gas flow rate with high accuracy.
However, since the price of one such carrier gas flow meter is about one-third as high as that of the gas chromatograph body, the gas chromatograph provided with a plurality of carrier gas flow paths as described above. In the Tograph, an expensive carrier gas flow meter is required for the number of flow paths, the cost of the device rises, and the price of the entire device becomes expensive. It is therefore desirable to reduce the cost of the device without making it impossible to measure and adjust multiple carrier gas flow rates.

On the other hand, the prior art disclosed in Japanese Patent Laid-Open No. 55-96451 only switches the supply of a plurality of sample gases in an appropriate order, and does not disclose the carrier gas flow path configuration. Therefore, it does not solve the above-mentioned problems related to the carrier gas flow rate measurement.

An object of the present invention is to provide a gas chromatograph capable of measuring the flow rate of a plurality of carrier gas flow paths and adjusting the flow rate, and reducing the cost of the apparatus by installing only one carrier gas flow meter. It is to provide a method for adjusting the carrier gas flow rate.

[0007]

To achieve the above object, according to the present invention, a column for separating the components of a sample by a carrier gas, and a detector for detecting the components of the sample separated by this column, In a gas chromatograph provided with a plurality of carrier gas flow paths including a flow rate controller that controls the flow rate of the carrier gas supplied to the column, and a pressure sensor that detects the pressure of the carrier gas,
One carrier gas flow meter for measuring the flow rate of any one of the carrier gas flow paths, and one of the carrier gas flow paths is selected to select the carrier gas flow path and the carrier gas flow rate. Flow path switching means for communicating with the meter, and flow path determination means for sending a command to the flow path switching means so that the carrier gas flow path in which the pressure fluctuation is detected by the pressure sensor is selected from among the carrier gas flow paths. There is provided a gas chromatograph having:

In order to achieve the above object, according to the present invention, the flow rate of the carrier gas in a gas chromatograph provided with a plurality of carrier gas channels for separating the components of the sample in the column by the carrier gas is adjusted. In the method for adjusting a carrier gas flow rate, the pressure of each of the carrier gases is detected, the carrier gas flow path in which the pressure fluctuation is detected is selected, and the carrier gas flow path is connected to one carrier gas flow meter. Also provided is a carrier gas flow rate adjusting method for a gas chromatograph, which comprises adjusting the flow rate of the carrier gas while measuring the flow rate of the carrier gas with the carrier gas flow meter.

[0009]

In the present invention constructed as described above, first, the carrier gas is caused to flow through each of the plurality of carrier gas passages in order to perform the analysis. Then, when the flow rate of the carrier gas is adjusted by the flow rate controller of one of the carrier gas flow paths, the pressure of the carrier gas in the carrier gas flow path fluctuates, and this pressure fluctuation is provided in the carrier gas flow path. Detected by the pressure sensor. At this time, the pressure of the carrier gas fluctuates while the flow rate is adjusted by the flow rate controller, that is, until the carrier gas flow rate reaches a constant target flow rate from the flow rate up to that point.

The detection result of the pressure sensor is sent to the flow path determining means, where it is determined which flow path is the carrier gas flow path in which the pressure has changed, and the flow path is switched so as to select the carrier gas flow path. A command is issued to the means. The flow path switching means selects the carrier gas flow path in which the pressure fluctuation has occurred, and connects the flow path with only one carrier gas flow meter. Then, the flow rate of the carrier gas in the selected flow path is measured by the carrier gas flow meter, and based on the measured flow rate, the flow rate is adjusted by the flow rate controller until a constant target flow rate to be adjusted is reached.

After the carrier gas flow rate reaches the constant target flow rate, only the flow path selected at that time communicates with the carrier gas flow meter, and the other flow paths do not communicate with the carrier gas flow meter. However, at this time, there is no need to measure the flow rate because the flow rate in any of the flow paths remains unchanged and constant. However, if the flow rate of any of the flow paths is adjusted by the flow rate controller, the adjusted flow path is selected by the same operation as above, and the flow path communicates with the carrier gas flow meter, Flow rate measurement will be performed.

That is, every time the flow rate controller adjusts the flow rate of one of the carrier gas flow paths, the adjusted flow path is automatically selected and communicated with the carrier gas flow meter, and the carrier gas of the flow path is adjusted. The flow rate can be measured. Therefore, it becomes possible to measure and adjust the flow rate of a plurality of carrier gas flow paths with a single carrier gas flow meter.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A gas chromatograph and a carrier gas flow rate adjusting method therefor according to an embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the gas chromatograph of this embodiment is provided with two systems of carrier gas flow paths 10 and 20, to each of which carrier gas is supplied from a carrier gas inlet 30. . Carrier gas flow path 10,
Reference numeral 20 denotes carrier gas flow rate controllers 11 and 21 for adjusting the flow rate of the carrier gas, pressure sensors 12 and 22 for detecting the pressure of the carrier gas, and a column 13 for containing a sample and separating its components by the carrier gas. , 2
3, inlets 14 and 24 for injecting the carrier gas into the columns 13 and 23, and detectors 15 and 25 for detecting the components of the sample separated in the columns 13 and 23. The carrier gas flow paths 10 and 20 are connected to a flow path switch 1 which is a six-way valve, and the flow path switch 1 is connected to a carrier gas flow meter 2 for measuring the flow rate of carrier gas. There is. Further, the flow path determiner 3 is electrically connected to the pressure sensors 12 and 22, and the flow path determiner 3 is further connected.
And the flow path switching device 1 are electrically connected. However, as the pressure sensors 12 and 22, for example, ordinary pressure gauges are used, and a detection signal based on the pressure display value is sent to the flow path determination unit 3.

Further, as shown in FIG. 2, the flow path determiner 3 includes a CPU 3a for data comparison, a memory 3b, and a command unit 3c.
Equipped with. A signal based on the pressure value is input to the CPU 3a from the pressure sensors 12 and 22, and is stored in the memory 3b as the first pressure value. Then, after a predetermined time, a signal based on the next pressure value is again input from the pressure sensors 12 and 22 to the CPU 3a, and the CPU 3a compares the pressure value with the initial pressure value in the memory 3b. At this time, if any one of the pressure values from the pressure sensors 12 and 22 is different between the second value and the first value, the pressure is applied to the carrier gas passage having the different pressure value. It is determined that fluctuation has occurred, and the command unit 3c is instructed to select the flow path by the flow path switching unit 1. As a result, a command is issued from the command unit 3c to the flow path switching unit 1, and the flow path switching unit 1 selects the carrier gas flow path in which the pressure fluctuation is occurring, and selects the selected carrier gas flow path and the carrier gas flow path. It communicates with the gas flow meter 2.

On the other hand, when the second and first pressure values are the same in the CPU 3a, the CPU 3a determines that there is no pressure fluctuation in any carrier gas passage, and the command unit 3
No command is sent to c, the flow path switching unit 1 does not operate, and the original state is maintained.

From the pressure sensors 12 and 22 to the CPU 3a
The signal input based on the pressure value is performed every predetermined time, and the input pressure value and the previous pressure value stored in the memory 3b are compared each time, and the command unit is based on the comparison result. A command is sent to 3c. Further, the previous pressure value is discarded in the memory 3b, and the newly input pressure value is stored and used for the next comparison. However, pressure sensor 1
The above-mentioned predetermined time, which is the interval between signal inputs from 2 and 22, is set to a sufficiently short appropriate time in advance.

Next, the operation of adjusting the flow rate of the carrier gas in the above-mentioned gas chromatograph will be described. First,
The carrier gas is supplied from the carrier gas inlet 30, and the carrier gas flows through the carrier gas passage 10 and the carrier gas passage 20. The carrier gas on the carrier gas flow path 10 side passes through the carrier gas flow rate controller 11 and the pressure sensor 1
After entering the port 1a of the flow path switcher 1 via 2, the flow path of the solid line in the flow path switcher 1 passes through the port 1b, and then the carrier gas flowmeter 2. The carrier gas passing through the carrier gas flow meter 2 enters the port 1e of the flow path switching device 1, passes through the flow path indicated by the solid line, and exits from the port 1f.
3 and is led to the detector 15. On the other hand, the carrier gas on the side of the carrier gas flow path 20 passes through the carrier gas flow rate controller 21, the pressure sensor 22, and enters the port 1c of the flow path switch 1, and passes through the solid line flow path in the flow path switch 1. From the port 1d, enters the column 23 from the inlet 24, and is guided to the detector 25. As described above, in the flow path switching device 1, the flow path indicated by the solid line in the figure, that is, the flow path in which the carrier gas flow path 10 communicates with the carrier gas flow meter 2 is selected first. At this time, the carrier gas flow rate of the carrier gas flow path 10 is displayed by the carrier gas flow meter 2. Further, in this embodiment, one type of carrier gas is used as the carrier gas inlet 30.
Are supplied to the carrier gas flow paths 10 and 20 from the above, but two different types of carrier gas may be supplied to the carrier gas flow paths.

When the flow rates of the carrier gas flow channels 10 and 20 are constant and stable, the indications of the pressure sensors 12 and 22 are also constant, and the flow channel determination unit 3 does not issue a command to the flow channel switching unit 1 and the carrier gas flow rate is changed. The above state in which the passage 10 communicates with the carrier gas flow meter 2 continues. In addition, as described above, the pressure value at that time is stored in the memory 3b of the flow path determiner 3. If the carrier gas flow rate controller 11 on the carrier gas flow path 10 side is adjusted to change the flow rate in this state,
Since a pressure fluctuation occurs in the carrier gas flow channel 10 and the pressure value is input from the pressure sensor 12 to the flow channel determination device 3,
The flow path determination unit 3 sends an instruction to the flow path switching unit 1 to select the carrier gas flow path 10. However, since the carrier gas flow path 10 is already selected in the flow path switcher 1 as described above, the flow path switcher 1 is maintained in the same state, and the carrier gas flowmeter 2 controls the carrier gas flow path 10. The flow rate can be monitored (measured). Then, while measuring the flow rate with the carrier gas flow meter 2, the flow rate is adjusted by the carrier gas flow rate controller 11 until a constant target flow rate to be adjusted is reached.

If the carrier gas flow rate controller 21 on the side of the carrier gas flow path 20 is adjusted to change the flow rate, a pressure fluctuation occurs in the carrier gas flow path 20, and the pressure value is changed from the pressure sensor 22 to the flow path determiner. 3, the flow path determiner 3 sends an instruction to the flow path switch 1 to select the carrier gas flow path 20. As a result, the flow path switching unit 1 operates and switches to the flow path indicated by the broken line in the figure. As a result,
The carrier gas on the side of the carrier gas flow path 20 comes from the port 1c of the flow path switch 1 through the flow path of the broken line in the flow path switch 1 and out of the port 1b, and passes through the carrier gas flow meter 2. The flow rate of the carrier gas channel 20 can be monitored (measured). The carrier gas that has passed through the carrier gas flow meter 2 enters the port 1e of the flow path switching device 1, passes through the flow path indicated by the broken line, exits from the port 1d, enters the column 23 through the injection port 24, and is guided to the detector 25. On the other hand, the carrier gas on the side of the carrier gas flow path 10 passes from the port 1a of the flow path switching device 1 through the flow path indicated by the broken line to the port 1f, enters the column 13 from the injection port 14 and is guided to the detector 15. Do not pass through the carrier gas flow meter 2.

In the above state, if the carrier gas flow rate controller 21 on the carrier gas flow channel 20 side is continuously adjusted to change the flow rate, pressure fluctuations continuously occur in the carrier gas flow channel 20, so the flow channel determination unit 3 Is the carrier gas flow path 2
An instruction is sent to the channel switching unit 1 to select 0 as it is, and the channel switching unit 1 maintains the state in which the carrier gas channel 20 is selected as it is. And the carrier gas flow meter 2
The flow rate is adjusted by the carrier gas flow rate regulator 21 until the constant target flow rate to be adjusted is reached while measuring the flow rate.

Thereafter, similarly to the above, when the carrier gas flow rate controller 11 on the carrier gas flow channel 10 side is adjusted to change the flow rate, the flow channel determination unit 3 sends a command to the flow channel switching unit 1 to send the carrier gas flow. Channel 10 is selected and carrier gas channel 20 is selected.
When the carrier gas flow rate controller 21 on the side is adjusted to change the flow rate, the flow channel determination unit 3 sends a command to the flow channel switching unit 1 to select the carrier gas flow channel 20. Then, the selected carrier gas flow path communicates with the carrier gas flow meter 2 to measure the flow rate, and the flow rate is adjusted until a constant target flow rate is reached. That is, each time the flow rate is adjusted by one of the carrier gas flow rate adjusters 11 and 21, the flow path determiner 3 determines which flow rate of the carrier gas flow path has been adjusted, and the carrier gas flow path of the adjusted carrier gas flow path is determined. Is automatically selected by the flow path switcher 1, and the flow rate can be adjusted while the carrier gas flow meter 2 measures the flow rate of the carrier gas in the flow path.

According to the present embodiment as described above, every time the flow rate is adjusted by one of the carrier gas flow rate controllers 11 and 21, the adjusted flow path is determined to be the flow path determining device 3 and the flow path switching device 1. The carrier gas flow rate of the selected flow path can be measured by one carrier gas flow meter 2 because it is automatically selected by. Therefore, even with one carrier gas flow meter 2, it is possible to perform flow rate measurement and flow rate adjustment of carrier gas flow paths of a plurality of systems (two systems in the case of this embodiment).

As a result, according to this embodiment, one carrier gas flowmeter 2 is used for the two carrier gas flow paths 10.
Since the carrier gas flow rates of 20 and 20 can be measured, the cost of the carrier gas flow meter can be greatly reduced to half that of the conventional one, and the space required for the carrier gas flow meter can be reduced, and the device can be downsized. Further, since the carrier gas flow passage whose flow rate is to be adjusted can be automatically selected and the flow rate can be measured, the operation is simplified and the reliability is greatly improved without causing an erroneous operation.

The present invention can also be applied to a gas chromatograph equipped with three or more carrier gas channels by replacing the switching valves of the above-described embodiments with corresponding ones.

[0026]

According to the present invention, each time the flow rate of one of the carrier gas flow paths is adjusted, the adjusted flow path is automatically selected. It can be measured with a carrier gas flow meter. Therefore,
Even one carrier gas flow meter can measure and adjust the flow rate of a plurality of carrier gas flow paths, which can significantly reduce the cost and downsize the device. In addition, the operation is simplified and the reliability is greatly improved without causing an erroneous operation.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a gas chromatograph according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a flow path determination device of the gas chromatograph shown in FIG.

[Explanation of symbols]

 1 flow path switching device 2 carrier gas flow meter 3 flow path determination device 3a CPU 3b memory 3c command section 10 carrier gas flow path 11 carrier gas flow rate controller 12 pressure sensor 13 column 15 detector 20 carrier gas flow path 21 carrier gas flow rate Regulator 22 Pressure sensor 23 Column 25 Detector

Claims (2)

[Claims] 1. A column for separating components of a sample by a carrier gas, a detector for detecting components of the sample separated by the column, and a flow rate controller for adjusting a flow rate of the carrier gas supplied to the column. And a gas chromatograph having a plurality of carrier gas flow paths including a pressure sensor for detecting the pressure of the carrier gas, wherein one carrier gas flow meter for measuring the flow rate of any one of the carrier gas flow paths, A channel switching means for selecting one of the carrier gas channels and connecting the carrier gas channel with the carrier gas flow meter; and a pressure sensor in the carrier gas channel. And a flow path determining means for sending a command to the flow path switching means so that the carrier gas flow path in which the pressure fluctuation is detected is selected. Gas chromatograph according to. 2. A carrier gas flow rate adjusting method for adjusting a flow rate of the carrier gas of a gas chromatograph provided with a plurality of carrier gas flow paths for separating components of a sample in a column by a carrier gas, wherein each of the carrier gas is adjusted. Detect the pressure, select the carrier gas flow path where the pressure fluctuation is detected, connect the carrier gas flow path to one carrier gas flow meter, and measure the flow rate of the selected carrier gas with the carrier gas flow meter. A method for adjusting a carrier gas flow rate of a gas chromatograph, characterized in that the flow rate is adjusted while controlling the flow rate.