JP5845966B2 - Gas chromatograph - Google Patents

Description

  The present invention relates to a gas chromatograph apparatus, and more particularly to a gas chromatograph apparatus that uses a combustible gas such as hydrogen gas as a make-up gas that flows into a carrier gas or a detector supplied to a column.

In the gas chromatograph, the sample gas is pushed by the carrier gas and introduced into the column from the inlet end of the column. Thus, each measurement substance contained in the sample gas is separated in the time axis direction while passing through the column, and reaches the outlet end of the column. At this time, in order to pass the sample gas through the column at a predetermined temperature, a column oven is used in which the column is accommodated and the temperature of the column is adjusted.
FIG. 2 is a schematic configuration diagram of an example of a conventional gas chromatograph apparatus. The gas chromatograph apparatus 101 supplies a column oven 2, a sample vaporization chamber 70 into which a sample is introduced, a carrier gas controller (carrier gas supply unit) 151 that supplies a carrier gas, a detector 60, and makeup gas. A makeup gas controller (makeup gas supply unit) 82, a column oven 2, a carrier gas controller 151, and a computer 120 that controls the makeup gas controller 82 are provided.

The column oven 2 includes a cubic housing 10 surrounded by four walls 12 on the top, bottom, left, and right, a back wall 16, and a front door 15 serving as a front wall. A passing column 11, a radial fan 14 for circulating air, and a heater 13 for heating air are accommodated.
The front door 15 is formed to be openable and closable with the left end as an axis. When the front door 15 is opened by an analyst, the column 11 accommodated in the housing 10 can be exchanged with another column. It can be done.
In addition, an exhaust port (not shown) is provided in the upper portion of the back wall 16, and an exhaust door can be opened and closed at the exhaust port. As a result, when the exhaust door is opened, the internal air can be discharged to the outside through the exhaust port. On the other hand, an intake port 33 is provided in the middle of the back wall 16, and an intake door 37 is formed in the intake port 33 so as to be openable and closable. As a result, when the intake door 37 is opened, external air can be introduced into the interior through the intake port 33.

Next, the sample vaporization chamber 70 and the carrier gas controller 151 will be described. FIG. 3 is an enlarged cross-sectional view of the sample vaporizing chamber 70 and the carrier gas controller 151.
The sample vaporizing chamber 70 includes a cylindrical metal casing 71 and a heater 78 that heats the outer peripheral surface of the casing 71.
The casing 71 can be divided into an upper casing 71b and a lower casing 71a. By dividing the casing 71, a cylindrical glass insert 77a can be arranged inside. .

The upper housing 71b is formed on the upper surface and has a sample introduction port 72 into which the sample S is introduced.
The lower casing 71a is formed on the left side wall, and is formed on the lower surface, the carrier gas introduction port 73 into which the carrier gas is introduced, the purge port 74 formed on the right side wall from which the carrier gas is discharged, and the inlet of the column 11 It has a column connection port 75 connected to the end, and a split port 76 formed on the right side wall for discharging a part of the sample gas injected into the housing 71 together with the carrier gas.

  A substantially cylindrical silicon rubber septum 72a is disposed in the sample introduction port 72, and the septum 72a is fixed to the upper casing 71b by being pressed downward by a septum nut 72b. In such a septum 72a, when an analyst performs an analysis, the sample S can be dropped into the housing 71 by piercing the septum 72a with the needle 91 of the microsyringe 90 in which the sample S is accommodated. It is like that. Since the septum 72a has elasticity, the hole opened when the needle 91 is inserted is immediately closed when the needle 91 is removed.

  Inside the lower housing 71a, a glass insert 77a is supported and disposed by an annular seal ring 77b. In such a glass insert 77a, when analyzing, the analyst places the needle 91 of the microsyringe 90 on the upper part of the internal space formed in the glass insert 77a, so that the sample S is placed in the internal space of the glass insert 77a. It will vaporize while passing from the upper side to the lower side.

The upper casing 71b is fixed to the upper casing 71b by being pressed downward by a seal nut 77c.
The column connection port 75 is connected to the inlet end of the column 11 and is fixed by a column nut 75a.

A carrier gas is sealed in the gas supply source 52. The gas supply source 52 is connected to one end of a gas introduction pipe, and the other end of the gas introduction pipe is connected to a carrier gas introduction port 73 via a flow meter 51a and a control valve 51b.
Flowmeter 51a is set a flow rate _{H 1} of the carrier gas time interval Delta] t ₁ (e.g., 6,18,240,360 milliseconds intervals) is to measure in.
With this configuration, by controlling the measurement while controlling valve 51b to flow H ₁ of the carrier gas at a set time interval Delta] t ₁ a flowmeter 51a, the carrier gas supplied to the carrier gas inlet 73 flow rate H ₁ Can be adjusted.

One end of a gas discharge pipe is connected to the split port 76, and a control valve 51f and a split vent 51g are arranged in the gas discharge pipe. Therefore, the control when the valve 51f is open, carrier gas of a certain percentage of the flow rate H ₄ is adapted to be discharged through the split opening 76.
One end of a gas discharge pipe is connected to the purge port 74, and a pressure gauge 51c and a control valve 51d for detecting the pressure inside the casing 71 are further arranged in the gas discharge pipe. Therefore, when the control valve 51d is open, the carrier gas of a certain percentage of the flow rate H ₃ is adapted to be discharged through the purge port 74.

Detector 60, for example, FID (flame ionization detector), FPD (flame photometric detector), a TCD (thermal conductivity detector), etc., released or is burned make-up gas flow rate H ₅ It is intended to be used.
A makeup gas is sealed in the gas supply source 81. The gas supply source 81 is connected to one end of a gas introduction pipe, and the other end of the gas introduction pipe is connected to the detector 60 via a control valve 82a, a pressure sensor 82b, and a resistance pipe 82c. Yes.
The pressure sensor 82b measures the pressure in the gas introduction pipe at a set time interval Δt ₁ (for example, intervals of 6, 18, 240, 360 milliseconds).
With this configuration, by controlling the control valve 82a while measuring the flow rate of H ₂ Make-up gas at set time intervals Delta] t ₁ between the pressure sensor 82b and the resistor tube 82c, makeup applied to the detector 60 thereby making it possible to adjust the flow rate of H ₂ gas.

  The computer 120 includes a CPU (control unit) 121 and a memory (storage unit) 122, and further includes an input device 23 having a keyboard, a mouse, and the like, and a display device 24. Further, the functions processed by the CPU 121 will be described as a block. The temperature control unit 121a for controlling the heater 13 and the like, the fan control unit 121b for controlling the radial fan 14, the carrier gas controller 151 and the makeup gas controller 82 are controlled. A flow control unit 121c that performs the analysis, and an analysis control unit 121d that receives a signal from the detector 60.

The flow rate controller 121 c receives the flow rate H measured by the flow meter 51 a at the set time interval Δt ₁ when the input device 23 inputs the flow rate of the carrier gas to “flow rate F” at “constant linear velocity”. _The control valve 51b, the control valve 51f, and the control valve 51d are controlled so that the “flow rate F” is obtained when “ ₁ is constant” by acquiring _1, and the flow rate of the carrier gas is “fixed pressure” by the input device 23. In order to obtain “pressure P” at “constant pressure” by obtaining the pressure measured by the pressure gauge 51c at the set time interval Δt ₁ 51b, control valve 51f, and control valve 51d are controlled.
“Constant linear velocity” means that the volume of the carrier gas passing through the cross-sectional area of the column 11 per unit time is controlled to be constant. Further, “constant pressure” means that the pressure detected by the pressure gauge 51c is controlled to be constant.

  Further, when the analysis temperature and the analysis time are input by the input device 23, the temperature control unit 121a supplies the heater 13 with energization power to heat the air, and the fan control unit 121b supplies the motor with the energization power. By rotating the radial fan 14 by circulating the heated air, the inside of the housing 10 can be brought to a uniform analysis temperature. At this time, when the temperature inside the housing 10 is lower than the analysis temperature, the temperature control unit 121a heats the air by closing the exhaust door and the intake door 37 and increasing the energization power to the heater 13. It will follow. On the other hand, when the temperature inside the housing 10 becomes higher than the temperature for analysis, the energized power to the heater 13 is reduced, and the exhaust door and the intake door 37 are opened so that the air at the outside room temperature is drawn into the intake port 33. And a part of the heated air is discharged to the outside through the exhaust port.

By the way, helium is often used as the carrier gas sealed in the gas supply source 52 or the makeup gas sealed in the gas supply source 82. This is because helium is superior or stable to other gases such as nitrogen and argon in terms of the performance of the column 11 called the number of theoretical plates, that is, the distribution efficiency. However, helium gas is concerned about resource depletion, and its price tends to rise.
For this reason, hydrogen gas is also superior to helium in terms of the number of theoretical plates, so that there is a strong demand to use hydrogen gas as a carrier gas and makeup gas from the viewpoint of running cost of analysis.

  However, in the gas chromatograph apparatus 101, daily maintenance such as replacement of the septum 72a and the glass insert 77a of the sample vaporizing chamber 70 and replacement of the column 11 of the column oven 2 is indispensable. Therefore, there is a case where the connection portion such as the septum 72a, the glass insert 77a, the column 11 or the like is loosened or the seal is insufficient after the replacement. May leak. For this reason, when the carrier gas is hydrogen gas, the use of hydrogen gas is avoided because the risk of explosion is high if the explosion limit concentration is exceeded inside the housing 10 at a high temperature. The explosion limit concentration of hydrogen gas is said to be about 4%.

  Therefore, a gas chromatograph apparatus is disclosed in which measures are taken when hydrogen gas leaks when hydrogen gas is used as the carrier gas (see, for example, Patent Document 1). In such a gas chromatograph apparatus, hydrogen contained in gas recovered from the inside of the column oven is detected by a hydrogen gas sensor, and when a hydrogen gas leak is detected, the hydrogen generator that supplies hydrogen as a carrier gas is stopped. I have to.

JP-A-5-346424

  However, in the gas chromatograph apparatus as described above, it is necessary to specially install a hydrogen gas sensor.

  In order to solve the above problems, the present inventors need to specially install a combustible gas sensor for detecting combustible gas when hydrogen gas or other combustible gas is used as carrier gas or makeup gas. We examined a method that can improve safety without any problems. Therefore, by setting the flow rate of the combustible gas supplied to the column 11 to be equal to or less than the flow rate α of the gas discharged from the inside of the housing 10 of the column oven 2, the combustible gas is explosive limit inside the housing 10. It has been found that the concentration can be prevented from exceeding.

That is, the gas chromatograph apparatus of the present invention supplies a sample to a column oven having a housing, a column disposed inside the housing, a heater for heating air inside the housing, and an inlet end of the column. A sample gasification chamber, a carrier gas supply to the sample vaporization chamber, a carrier gas supply unit having a first flow meter for measuring the flow rate of the carrier gas at a set time interval, and an outlet end of the column. And a controller for controlling the heater and the carrier gas supply unit, wherein the carrier gas is a flammable gas and has an explosion limit concentration in the housing. for determining the presence of the carrier gas is diffused and released from the inside to the outside of the column oven housing A storage unit for storing the flow rate threshold value is the amount, wherein, when the flow rate of the flammable gas supplied to the column is greater than or equal to the flow rate threshold, stops the power supply to the heater, the sample The supply of combustible gas to the vaporization chamber is stopped.

Here, the “set time interval” is an arbitrary time interval, for example, a time interval determined in advance by the detection speed of the flow meter.
According to the gas chromatograph apparatus of the present invention, when the flow rate of the combustible gas supplied to the column is equal to or higher than the flow rate threshold value, the control unit is assumed that the combustible gas having an explosion limit concentration is present in the housing. judge. When recognizing that the explosive limit concentration of combustible gas is present inside the housing, the control unit immediately stops the power supply to the heater and stops supplying the combustible gas. Accordingly, the temperature inside the column oven is lowered, and the combustible gas existing inside the housing is discharged to the outside, so that the risk of ignition can be avoided.

  As described above, according to the gas chromatograph apparatus of the present invention, when hydrogen gas or other flammable gas is used as a carrier gas or makeup gas, it is not necessary to install a flammable gas sensor and safety is improved. Can be increased. Further, it is possible to prevent the column from being deteriorated by being exposed to a high temperature in a state where the carrier gas is blocked.

(Means and effects for solving other problems)
In the above invention, the sample vaporizing chamber has a supply flow path for supplying a combustible gas to the inlet end of the column and a discharge flow path for discharging the combustible gas to the outside, and the carrier gas supply The unit has a second flow meter that measures the flow rate of the combustible gas flowing through the discharge flow path at a set time interval, and the control unit determines the second flow rate from the flow rate measured by the first flow meter. When the flow rate obtained by subtracting the flow rate measured by the meter is equal to or higher than the flow rate threshold value, the supply of electric power to the heater may be stopped and the supply of combustible gas to the inlet end of the column may be stopped.

In the above invention, the makeup gas is supplied to the detector and includes a makeup gas supply unit having a third flow meter for measuring the flow rate of the makeup gas at a set time interval. Is a flammable gas, and the control unit measures the flow rate measured by the second flow meter from the total flow rate of the flow rate measured by the first flow meter and the flow rate measured by the third flow meter. When the flow rate obtained by subtracting the flow rate used by the detector is equal to or greater than the flow rate threshold value, the power supply to the heater is stopped and the supply of combustible gas to the inlet end of the column is stopped. May be.
Here, the “third flow meter” only needs to be able to measure the flow rate of the makeup gas at set time intervals, and may be substituted with a combination of a pressure gauge and a resistance tube.

Furthermore, in the above invention, the control unit stops power supply to the heater based on a flow rate that is longer than the set time interval, and supplies flammable gas to the inlet end of the column. May be stopped.

The schematic block diagram of an example of the gas chromatograph apparatus which concerns on this invention. The schematic block diagram of an example of the conventional gas chromatograph apparatus. The expanded sectional view of a sample vaporization chamber and a carrier gas controller.

  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 is needless to say that various aspects are included without departing from the gist of the present invention.

FIG. 1 is a schematic configuration diagram of 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 gas chromatograph apparatus 101 mentioned above.
The gas chromatograph apparatus 1 supplies a column oven 2, a sample vaporization chamber 70 into which a sample is introduced, a carrier gas controller (carrier gas supply unit) 51 that supplies a carrier gas, a detector 60, and a makeup gas. A makeup gas controller (makeup gas supply unit) 82, a column oven 2, a carrier gas controller 51, and a computer 20 that controls the makeup gas controller 82 are provided.
And the hydrogen gas is enclosed with the gas supply sources 52 and 81 which concern on this invention.

One end of a gas discharge pipe is connected to the split port 76, and a control valve 51f, a split vent 51g, and a second flow meter 51i are arranged in the gas discharge pipe. Therefore, the control when the valve 51f is open, carrier gas of a certain percentage of the flow rate H ₄ is adapted to be discharged through the split opening 76. Incidentally, the second flowmeter 51i is set the flow rate _{H 4} of the carrier gas time interval Delta] t ₁ (e.g., 6,18,240,360 milliseconds intervals) is to measure in.
The second flow meters 51i and 51h can be virtual flow meters by calculating the flow rate from the pressure of the pressure gauge 51c, the flow path resistance of the control valves 51f and 51d, and the valve opening / closing speed.

One end of a gas discharge pipe is connected to the purge port 74, and a pressure gauge 51c, a control valve 51d, and a second flow meter 51h for detecting the pressure inside the housing 71 are further arranged in the gas discharge pipe. ing. Therefore, when the control valve 51d is open, the carrier gas of a certain percentage of the flow rate H ₃ is adapted to be discharged through the purge port 74. Incidentally, the second flowmeter 51h is set the flow rate _{H 3} of the carrier gas time interval Delta] t ₁ (e.g., 6,18,240,360 milliseconds intervals) is to measure in.

  The computer 20 includes a CPU (control unit) 21 and a memory (storage unit) 22, and an input device 23 having a keyboard, a mouse, and the like, and a display device 24 are connected to each other. Further, the functions processed by the CPU 21 will be described as a block. The temperature control unit 21a for controlling the heater 13 and the like, the fan control unit 21b for controlling the radial fan 14, the carrier gas controller 51 and the makeup gas controller 82 are controlled. And a flow rate control unit 21c that receives the signal from the detector 60.

The memory 22 stores in advance a flow rate threshold value α ₁ (for example, 500 mL / min) for determining the presence of hydrogen gas having an explosion limit concentration (for example, 4%) inside the housing 10. The flow rate threshold value α ₁ is the flow rate of the gas discharged from the inside of the housing 10 of the column oven 2 to the outside. The flow rate threshold value α ₁ is determined in advance from the structure (size of the gap) of the housing 10 by a designer or the like and stored in the memory 22. Will be.

The flow rate control unit 21c was measured by the first flow meter 51a at the set time interval Δt ₁ by inputting the carrier gas flow rate to “flow rate F” at “linear velocity constant” by the input device 23. as the "flow F" in "constant linear velocity" by obtaining the flow rate H _1, and controls the control valve 51b and control valve 51d and the control valve 51f, the flow rate of the carrier gas by the input device 23 is "pressure By being input so as to become “pressure P” at “constant”, the pressure measured by the pressure gauge 51c at the set time interval Δt ₁ is acquired so that “pressure P” becomes “pressure P” at “constant pressure”. The control valve 51b, the control valve 51d, and the control valve 51f are controlled.

The flow rate control section 21c, settings during the analysis time interval Delta] t _1, the flow rate H ₁ measured at the first flowmeter 51a, a flow rate H ₃ measured by the second flowmeter 51h, the second flowmeter a flow rate _{H 4} measured at 51i, by acquiring the pressure measured by the pressure sensor 82b, as shown in the following formula (1), and the flow rate _{H 1,} the pressure sensor 82b and the resistance tube 82c (third The flow rate obtained by subtracting the flow rate H ₃ , the flow rate H _4, and the flow rate H ₅ used by the detector 60 from the total flow rate (H ₁ + H ₂ ) with the flow rate H ₂ calculated by the flow meter) is a flow rate threshold α _1. Whether or not the above has been reached is determined by the set time interval Δt ₁ . Then, when it is determined that it is the flow threshold alpha ₁ or more, in the detector 60. and the inlet end of the column 11 immediately controls the control valve 51b and control valve 82a to stop the supply of hydrogen gas, immediately heater A signal is output to the temperature control unit 21a so as to stop the power supply to 13. At this time, in order to promote the discharge of hydrogen gas accumulated in the housing 10, the rotational speed of the radial fan 14 may be increased to increase the air volume.
(H ₁ + H ₂ ) − (H ₃ + H ₄ + H ₅ ) ≧ α ₁ (1)

  As described above, according to the gas chromatograph apparatus 1 of the present invention, when hydrogen gas is used as a carrier gas or makeup gas, it is not necessary to install a hydrogen gas sensor specially, and safety can be improved. Further, it is possible to prevent the column 11 from being deteriorated by being exposed to a high temperature in a state where the hydrogen gas is blocked.

<Other embodiments>
<1> In the gas chromatograph apparatus 1 described above, the configuration in which the supply of hydrogen gas is stopped at the inlet end of the column 11 and the detector 60 is shown. However, when the detector 60 is not FID, FPD, or TCD, hydrogen gas is supplied. Therefore, the supply of hydrogen gas to the inlet end of the column 11 may be stopped based on the following formula (2).
H ₁ − (H ₃ + H ₄ ) ≧ α ₁ (2)

<2> In the gas chromatograph apparatus 1 described above, the configuration in which the supply of hydrogen gas to the inlet end of the column 11 and the detector 60 is stopped based on the formula (1) is shown. 11 may be configured to stop the supply of hydrogen gas to the inlet end of 11 and the detector 60. At this time, it is not necessary to install the second flow meter 51h and the second flow meter 51i.
(H ₁ + H ₂ ) −H ₅ ≧ α ₁ (3)

<3> In the gas chromatograph apparatus 1 described above, the configuration in which the supply of hydrogen gas to the inlet end of the column 11 and the detector 60 is stopped based on the formula (1) is shown. 11 may be configured to stop the supply of hydrogen gas to the inlet end of 11 and the detector 60.
(H ₁ × Δt ₂ + H ₂ × Δt ₂ ) − (H ₃ × Δt ₂ + H ₄ × Δt ₂ + H ₅ × Δt ₂ ) ≧ α ₁ × Δt ₂ (4)
However, (Δt ₂ / Δt ₁ ) = n, and n is a positive integer.
Incidentally, at this time, may determine whether or not it is the flow rate threshold value alpha ₁ or more at set time intervals Delta] t _1, it may be determined at set time intervals Delta] t _2.
According to such a gas chromatographic apparatus, even by passing a short time if it exceeds the alpha ₁ mL / min gas, by limiting the amount of gas before and after the following alpha ₁ mL / min, the housing 10 By utilizing the fact that the concentration of hydrogen gas inside does not reach the explosion limit concentration, the flow rate can be increased for a short time.

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

DESCRIPTION OF SYMBOLS 1 Gas chromatograph apparatus 2 Column oven 10 Housing 11 Column 13 Heater 21 Control part 22 Memory (memory | storage part)
51 Carrier gas controller (carrier gas supply unit)
51a First flow meter 60 Detector 70 Sample vaporization chamber

Claims (4)

A column oven comprising a housing, a column disposed inside the housing, and a heater for heating air inside the housing;
A sample vaporization chamber for supplying a sample to the inlet end of the column;
A carrier gas supply unit having a first flow meter for supplying a carrier gas to the sample vaporizing chamber and measuring a flow rate of the carrier gas at set time intervals;
A detector connected to the outlet end of the column;
A gas chromatograph apparatus comprising a control unit for controlling the heater and the carrier gas supply unit,
The carrier gas is a combustible gas,
In order to determine the presence of an explosive limit concentration of flammable gas inside the housing, the storage unit stores a flow rate threshold value that is a flow rate of the carrier gas diffused / released from the inside of the housing of the column oven ,
When the flow rate of the combustible gas supplied to the column is equal to or higher than a flow rate threshold, the control unit stops the power supply to the heater and stops the supply of the combustible gas to the sample vaporizing chamber. A gas chromatograph apparatus characterized by the above. The sample vaporization chamber has a supply flow path for supplying a combustible gas to the inlet end of the column, and a discharge flow path for discharging the combustible gas to the outside.
The carrier gas supply unit has a second flow meter that measures the flow rate of the combustible gas flowing through the discharge passage at set time intervals,
When the flow rate obtained by subtracting the flow rate measured by the second flow meter from the flow rate measured by the first flow meter is equal to or higher than a flow rate threshold, the control unit stops power supply to the heater, and The gas chromatograph according to claim 1, wherein the supply of the combustible gas to the inlet end of the column is stopped. A makeup gas supply unit having a third flow meter for supplying makeup gas to the detector and measuring a flow rate of the makeup gas at set time intervals,
The makeup gas is a combustible gas,
The control unit was used in the flow rate measured by the second flow meter and the detector from the total flow rate of the flow rate measured by the first flow meter and the flow rate measured by the third flow meter. The power supply to the heater is stopped and the supply of combustible gas to the inlet end of the column is stopped when the flow rate obtained by subtracting the flow rate is equal to or higher than a flow rate threshold value. Gas chromatograph equipment. The control unit stops power supply to the heater based on a flow rate that is longer than the set time interval, and stops supply of combustible gas to the inlet end of the column. The gas chromatograph apparatus according to any one of claims 1 to 3.

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