Gas analyzer and calibration gas supply method

Abstract

To ensure that a component of interest in a calibration gas is suppressed from being adsorbed to the inside of a piping and a calibration gas of accurate concentration is supplied to a measurement unit.SOLUTION: A gas analysis system (1) comprises a measurement unit (2), a calibration gas supply unit (4) that supplies a calibration gas to the measurement unit, and a control unit (76) The calibration gas supply unit includes a soured gas cylinder (44), a diluent gas cylinder (46), a confluence unit (74) by which a source gas supplied from the source gas cylinder and a diluent gas supplied from the diluent gas cylinder are jointed together, a regulator (48) for adjusting the supply pressure of the source gas cylinder, and a flow rate adjustment mechanism (70) for controlling the flow rate of the diluent gas supplied from the diluent gas cylinder. The flow rate of a source gas supplied from the source gas cylinder is adjusted by only the regulator. The control unit controls the concentration of a component of interest in the calibration gas to a target concentration by only the flow rate adjustment mechanism, on the basis of the source gas supply pressure that is fixed to prescribed pressure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas analyzer and a calibration gas supply method. [Background technology]

[0002] There are various devices for measuring the concentration of a specific component contained in a gas, but all of them require a calibration curve that shows the relationship between the detector signal and the concentration of the specific component. In order to create a calibration curve, it is necessary to calibrate the measurement value using a calibration gas whose concentration of the specific component is known (see Patent Document 1).

[0003] BTX (B: benzene, T: toluene, X: xylene) is a typical air pollutant, but the amount of BTX present in the atmosphere is extremely small. Therefore, in order to measure the concentration of BTX in the atmosphere, a calibration gas with an extremely low concentration of BTX must be used to calibrate the measurement value. Meanwhile, the minimum concentration of BTX source gas that can be filled into a cylinder is usually around 10 ppm. If a calibration gas with a lower concentration is required, the source gas must be diluted with a diluent gas such as N2 (nitrogen) gas to create a calibration gas of the required concentration. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-304213 Summary of the Invention [Problem to be solved by the invention]

[0005] Substances such as BTX have higher boiling points than other substances (for example, the boiling point of benzene is approximately 80°C, and that of xylene is approximately 140°C), and they tend to liquefy at room temperature and are easily adsorbed to the inner walls of piping. In particular, gas measurement devices that measure BTX and other substances in the atmosphere must use calibration gases that contain only low concentrations of target components such as BTX. However, if the target components are adsorbed in the piping leading to the measurement unit, the concentration of the target component in the calibration gas introduced into the measurement unit will be lower than the desired concentration, making accurate calibration impossible.

[0006] Therefore, the present invention aims to prevent the target components contained in the calibration gas from being adsorbed in the piping leading to the measurement unit, thereby ensuring that calibration gas of an accurate concentration is supplied to the measurement unit. [Means for solving the problem]

[0007] When preparing a low-concentration calibration gas by diluting a source gas containing a high-boiling-point substance such as BTX, it is common to use a flow controller (e.g., a mass flow controller) to control the flow rates of the source gas and the dilution gas so that the flow ratio of the source gas to the dilution gas corresponds to the desired dilution factor. The inventors of the present invention have found that the internal flow path configuration of a flow controller is complex, and that portions within the flow controller where the gas flow rate is extremely slow are likely to be formed, making it easy for the target component to adsorb to these portions. The inventors then came up with the idea of ​​simplifying the flow path configuration of the source gas flow path by eliminating the flow controller from the flow path of the source gas used to prepare the calibration gas, while enabling the preparation of a calibration gas of a desired concentration. The present invention is based on this idea. The outline of the present invention is as follows.

[0008] A gas analyzer according to the present invention includes a measurement unit for measuring the concentration of a target component in a gas, a calibration gas supply unit for supplying the measurement unit with a calibration gas used to calibrate the measurement value of the measurement unit, and a control unit for controlling the operation of the measurement unit and the calibration gas supply unit. The calibration gas supply unit includes a source gas cylinder for supplying a source gas containing the target component at a known concentration, a dilution gas cylinder for supplying a dilution gas for diluting the source gas, a junction unit for junctioning the source gas supplied from the source gas cylinder with the dilution gas supplied from the dilution gas cylinder to produce the calibration gas, a regulator provided between the source gas cylinder and the junction unit for adjusting the supply pressure of the source gas supplied from the source gas cylinder to the junction unit, and a flow rate adjustment mechanism provided between the dilution gas cylinder and the junction unit for controlling the flow rate of the dilution gas supplied from the dilution gas cylinder to the junction unit. The supply flow rate of the source gas from the source gas cylinder is regulated only by the regulator. The control unit is configured to, when supplying the calibration gas from the calibration gas supply unit to the measurement unit, adjust the concentration of the target component in the calibration gas to the target concentration using only the flow rate adjustment mechanism based on the supply pressure of the source gas fixed at the predetermined pressure, while the supply pressure of the source gas is fixed at the predetermined pressure by the regulator, and the gas analyzer is configured to extract only the flow rate required for analysis from the calibration gas adjusted to the target concentration at the junction and use it for measurement in the measurement unit.

[0009] A calibration gas supply method according to the present invention is a calibration gas supply method in which a source gas containing a target component at a known concentration and a dilution gas for diluting the source gas are merged at a junction to create a calibration gas, and the calibration gas is supplied to a measurement section for measuring the concentration of the target component in the gas. The method includes, in this order, a source gas supply step of supplying the source gas to the junction while fixing the supply pressure of the source gas from a source gas cylinder that supplies the source gas at a predetermined pressure using only a regulator; a flow rate calculation step of calculating a required flow rate of the dilution gas for adjusting the concentration of the target component in the calibration gas produced at the junction to a target concentration based on the supply pressure of the source gas from the source gas cylinder that is fixed at the predetermined pressure; a flow rate control step of controlling the supply flow rate of the dilution gas from the dilution gas cylinder using a flow rate adjustment mechanism so that the flow rate of the dilution gas supplied from the dilution gas cylinder to the junction becomes the required flow rate calculated in the flow rate calculation step; and a calibration gas extraction step of extracting a predetermined flow rate of the calibration gas in which the concentration of the target component has been adjusted to the target concentration at the junction, and using the extracted flow rate for measurement in the measurement unit. [Effects of the Invention]

[0010] In the gas analyzer according to the present invention, the concentration of a target component in the calibration gas supplied from the calibration gas supply unit to the measurement unit is adjusted to a target concentration by controlling the flow rate of the dilution gas while fixing the supply pressure of the source gas containing the target component. With this configuration, there is no flow controller in the source gas flow path, so that the target component is not adsorbed in the piping of the flow controller, and calibration gas of an accurate concentration can be supplied to the measurement unit.

[0011] In the calibration gas supply method according to the present invention, when supplying calibration gas to a measurement unit, the supply pressure of the source gas is fixed only by a regulator, and the flow rate of the dilution gas is controlled by a flow rate adjustment mechanism to adjust the concentration of the target component in the calibration gas to a target concentration. This eliminates the need to place a flow controller in the source gas flow path, prevents the target component from being adsorbed in the piping of the flow controller, and allows calibration gas of accurate concentration to be supplied to the measurement unit. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram showing an embodiment of a gas analysis system. [Figure 2] FIG. 10 is a diagram for explaining the flow of calibration gas when target components in a calibration gas prepared by dilution are collected in a collection tube in the same example. [Figure 3] FIG. 10 is a diagram for explaining the flow of calibration gas when target components in undiluted calibration gas are collected in a collection tube in the same embodiment. [Figure 4] FIG. 2 is a diagram for explaining the flow of calibration gas when target components in a sample gas are collected in a collection tube in the same embodiment. [Figure 5] FIG. 2 is a diagram for explaining the gas flow when measuring the target components collected in the collection tube in the same example. [Figure 6] 4 is a flowchart showing an example of a calibration gas preparation operation of the calibration gas supply unit in the embodiment. [Figure 7] 10 is a flowchart showing an example of an operation for calculating a flow rate (default flow rate) of a source gas when the supply pressure of a source gas cylinder of a calibration gas supply unit is set to a predetermined pressure. [Figure 8] 10 is a flowchart illustrating another example of the operation for calculating a default flow rate. [Figure 9] FIG. 10 is a flow path configuration diagram for explaining a modified example of the flow path configuration of the calibration gas supply unit of the gas analysis system. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of a gas analysis system and a calibration gas supply method according to the present invention will be described with reference to the drawings.

[0014] 1, the gas analysis system 1 includes a measurement unit 2, a calibration gas supply unit 4, a control unit 76, and a flow rate memory unit 78. In this embodiment, the measurement unit 2 is a gas chromatograph, and the target component to be measured is, for example, BTX contained in the air.

[0015] The measurement section 2 includes a branching section 10 , a multiport valve 12 , a collection tube 14 , a first separation column 16 , a second separation column 18 , a detector 20 , and a suction pump 22 .

[0016] The branching section 10 is connected to a sample gas flow path 6, a calibration gas flow path 8, an inlet flow path 24, and an outlet flow path 40. The sample gas flow path 6 is a flow path for supplying sample gas to the measurement section 2. The calibration gas flow path 8 is a flow path for supplying calibration gas from the calibration gas supply section 4 to the measurement section 2. The inlet flow path 24 is a flow path through which the sample gas supplied through the sample gas flow path 6 or the calibration gas supplied through the calibration gas flow path 8 flows, and is connected to one port a of the multiport valve 12. The outlet flow path 40 is a flow path for discharging a portion of the calibration gas supplied from the calibration gas supply section 4 to the outside. A stop valve 42 is provided on the outlet flow path 40. The branching section 10 may be a joint that connects multiple pipes to each other, or may be a switching mechanism such as a multiport valve.

[0017] The collection tube 14 is provided on the collection flow path 26 to collect target components contained in the sample gas and calibration gas introduced through the introduction flow path 24. One end of the collection flow path 26 is connected to port j, which is adjacent to port a of the multiport valve 12 and to which the introduction flow path 24 is connected, and the other end of the collection flow path 26 is connected to port b, which is adjacent to port c of the multiport valve 12 and to which the suction flow path 32 is connected. A suction pump 22 is provided on the suction flow path 32. In the multiport valve 12, port a, to which the introduction flow path 24 is connected, and port b, to which the suction flow path 32 is connected, are adjacent to each other.

[0018] The first separation column 16 and the second separation column 18 are used to individually separate target components in the sample gas and the calibration gas. The first separation column 16 is provided on a first separation flow path 28, and the second separation column 18 is provided on a second separation flow path 30. One end of the first separation flow path 28 is connected to port i of the multiport valve 12, and the other end of the first separation flow path 28 is connected to port e of the multiport valve 12.

[0019] In the multiport valve 12, port i, to which one end of the first separation channel 28 is connected, is located between port j, to which one end of the collection channel 26 is connected, and port h, to which the drain channel 38 is connected, and port e, to which the other end of the first separation channel 28 is connected, is located between port d, to which the first carrier gas channel 34 is connected, and port f, to which the upstream end of the second separation channel 30 is connected. In the multiport valve 12, port g, which is located between port f, to which the upstream end of the second separation channel 30 is connected, and port h, to which the drain channel 38 is connected, is connected to a second carrier gas channel 36. The downstream end of the second separation channel 30 communicates with the detector 20. The first carrier gas channel 34 and the second carrier gas channel 36 are channels for supplying a carrier gas (e.g., nitrogen gas).

[0020] The multi-port valve 12 is a two-position valve that can be switched between either a first state (the state in FIG. 1) in which ports aj, bc, de, fg, and hi are connected, or a second state (the state in FIG. 4) in which ports ab, cd, ef, gh, and ij are connected.

[0021] The detector 20 outputs a signal corresponding to the concentration of the target component eluted from the first separation column 16 and the second separation column 18. The type of detector 20 is not particularly limited, but a flame ionization detector (FID) or a thermal conductivity detector (TCD) can be used as the detector 20.

[0022] The calibration gas supply unit 4 is configured to be able to supply a calibration gas containing a target component at a desired concentration to the measurement unit 2. The calibration gas supply unit 4 is provided with a source gas cylinder 44 that supplies a source gas containing a target component at a known concentration, and a dilution gas cylinder 46 that supplies a dilution gas (e.g., nitrogen gas) for diluting the source gas.

[0023] A regulator 48 for adjusting the supply pressure is provided at the outlet of the source gas cylinder 44, and a source gas flow path 50 is connected downstream of the regulator 48. The source gas flow path 50 branches into a dilution flow path 52, an undiluted flow path 54, and a purge flow path 64. A stop valve 56 and a resistance tube 58 are provided on the dilution flow path 52, a stop valve 60 and a resistance tube 62 are provided on the undiluted flow path 54, and a stop valve 66 is provided on the purge flow path 64. The dilution flow path 52, the undiluted flow path 54, and the purge flow path 64 are opened and closed by the stop valves 56, 60, and 66, respectively. The dilution flow path 52 is used when diluting the source gas from the source gas cylinder 44 with a dilution gas to produce a calibration gas, and the undiluted flow path 54 is used when producing the source gas from the source gas cylinder 44 as a calibration gas without dilution. The resistance tube 62 provided on the undiluted flow path 54 has a smaller flow path resistance than the resistance tube 58 provided on the dilution flow path 52. Therefore, when the source gas is used as the calibration gas without dilution, the source gas can be flowed at a higher flow rate than when the source gas is diluted to use as the calibration gas.

[0024] A regulator 68 for adjusting the supply pressure is provided at the outlet of the dilution gas cylinder 46, and a dilution gas flow path 69 is connected downstream of the regulator 68. A pressure controller 70 and a resistance tube 72 are provided on the dilution gas flow path 69 as a flow rate adjustment mechanism. The flow rate of the dilution gas flowing through the dilution gas flow path 69 is controlled by the pressure controller 70. Note that a flow controller such as a mass flow controller can be used instead of the pressure controller 70.

[0025] The dilution flow path 52 , the non-dilution flow path 54 , and the diluted gas flow path 69 join at a joining point 74 and are fluidly connected to the branching point 10 .

[0026] In the calibration gas supply unit 4, by opening the stop valve 66 of the purge flow path 64 after the supply of calibration gas has finished, the gas in the flow path from the source gas cylinder 44 to the stop valves 56 and 60 can be purged to the outside. In FIG. 1, the purge flow path 64 is provided so as to branch off from the non-dilution flow path 54, but the same function can be achieved even if the purge flow path 64 is provided in a different position. In the modification shown in FIG. 9, the purge flow path 64 is provided so as to branch off from the dilution flow path 52 at a position between the stop valve 56 and the resistance tube 58. Because the resistance tube 58 has a larger flow resistance than the resistance tube 62, a high pressure is maintained between the stop valve 56 and the resistance tube 58 even after the supply of source gas through the dilution flow path 52 has finished and the stop valve 56 is closed, which may cause the source gas to leak toward the branching section 10. 9, if the purge flow path 64 is provided so as to branch off from the dilution flow path 52 at a position between the stop valve 56 and the resistance tube 58, the residual pressure between the stop valve 56 and the resistance tube 58 can be removed by slightly opening the stop valve 66 after the supply of the source gas through the dilution flow path 52 has finished. Note that the source gas flow path 50 can be purged by simultaneously opening the stop valves 56 and 66.

[0027] Here, in order to suppress adsorption of target components in the source gas inside the resistance tubes 58 and 62 provided in the dilution flow path 52 and the non-dilution flow path 54, it is preferable that the resistance tubes 58 and 62 be heated to a certain temperature or higher (e.g., 80°C) by some kind of heater element. In this embodiment, the measurement unit 2 is a gas chromatograph and is equipped with a column oven (not shown) for heating the first separation column 16 and the second separation column 18 and controlling them to a constant temperature. Therefore, the resistance tubes 58 and 62 can be housed and heated together with the first separation column 16 and the second separation column 18 in the column oven. In other words, the column oven of the gas chromatograph 2 can be used as a heater element for heating the resistance tubes 58 and 62.

[0028] Next, the operation when measuring target components in the calibration gas and sample gas will be described with reference to FIGS.

[0029] When supplying source gas diluted with dilution gas as calibration gas from the calibration gas supply unit 4 to the measurement unit 2, as shown in FIG. 2, the source gas is supplied to the junction 74 through the dilution flow path 52, and the dilution gas is supplied to the junction 74 through the dilution gas flow path 69. The source gas is diluted with the dilution gas at the junction 74 to become calibration gas, which is then supplied to the measurement unit 2 through the calibration gas flow path 8. In the measurement unit 2, the multiport valve 12 is set to a first state in which the introduction flow path 24, the collection flow path 26, and the suction flow path 32 are connected in series. At this time, the suction pump 22 is operated so that only a predetermined flow rate of the calibration gas supplied to the branch 10 is drawn into the collection flow path 26, and the target component in the calibration gas is collected in the collection tube 14. The portion of the calibration gas supplied to the branch 10 that is not drawn into the collection flow path 26 is discharged to the outside through the discharge flow path 40. The adjustment of the target component concentration in the calibration gas in the calibration gas supply unit 4 will be described later.

[0030] When the source gas is supplied from the calibration gas supply unit 4 to the measurement unit 2 as a calibration gas without dilution, only the source gas is supplied to the measurement unit 2 through the undiluted flow path 54 and the calibration gas flow path 8, as shown in Figure 3. In the measurement unit 2, the multiport valve 12 is set to a first state in which the introduction flow path 24, the collection flow path 26, and the suction flow path 32 are connected in series. At this time, the suction pump 22 is operated so that only a predetermined flow rate of the calibration gas supplied to the branch unit 10 is drawn into the collection flow path 26, and the target component in the calibration gas is collected in the collection tube 14. The portion of the calibration gas supplied to the branch unit 10 that is not drawn into the collection flow path 26 is discharged to the outside through the discharge flow path 40.

[0031] 4, the multiport valve 12 is set to the first state in which the introduction flow path 24, collection flow path 26, and suction flow path 32 are connected in series. At this time, the suction pump 22 is operated so that the sample gas is drawn into the collection flow path 26 at a predetermined flow rate, and the target components in the sample gas are collected in the collection tube 14.

[0032] 2 to 4, the target components in the calibration gas or the target components in the sample gas collected in the collection tube 14 by the operations in Figures 2 to 4 are measured by placing the multiport valve 12 in a second state in which the first carrier gas flow path 34, the collection flow path 26, the first separation flow path 28, and the second separation flow path 30 are connected in series, and supplying carrier gas from the first carrier gas flow path 34, as shown in Figure 5. The target components collected in the collection tube 14 are transported to the first separation column 16 and the second separation column 18 by the carrier gas supplied from the first carrier gas flow path 34, where they are separated over time into individual components and eluted, and then introduced into the detector 20, where signals based on their respective concentrations are obtained.

[0033] Next, the adjustment of the concentration of the target component in the calibration gas in the calibration gas supply unit 4 will be described with reference to the flowchart of FIG. 6 together with FIG.

[0034] When the calibration gas is supplied from the calibration gas supply unit 4 to the measurement unit 2, the control unit 76 sets a target concentration of the target component in the calibration gas (step 101). The regulator 48 provided at the outlet of the source gas cylinder 44 is adjusted so that the supply pressure of the source gas becomes a predetermined pressure (step 102). The adjustment of the regulator 48 may be performed automatically by the control unit 76 or manually by the user. The supply flow rate of the source gas when the supply pressure of the source gas cylinder 44 is adjusted to the predetermined pressure is stored as a default flow rate in the flow rate memory unit 78. The default flow rate stored in the flow rate memory unit 78 is calculated by a flow rate calculation operation that has been executed in advance. The flow rate calculation operation will be described later.

[0035] The control unit 76 calculates the required flow rate of the dilution gas for adjusting the concentration of the target component in the calibration gas prepared in the junction 74 to the target concentration (step 103), assuming that the flow rate of the source gas supplied from the source gas cylinder 44 to the junction 74 is the default flow rate stored in the flow rate memory unit 78. Then, the control unit 76 controls the flow rate of the dilution gas supplied to the junction 74 to the required flow rate obtained by calculation using the pressure controller 70 (step 104).

[0036] As described above, the control unit 76 controls the concentration of the target component in the calibration gas supplied from the calibration gas supply unit 4 to the measurement unit 2 to the target concentration by controlling only the flow rate of the dilution gas using the pressure controller 70 while keeping the supply pressure and supply flow rate from the source gas cylinder 44 constant.

[0037] Here, an example of a default flow rate calculation operation for calculating the flow rate (default flow rate V0) of the source gas when the supply pressure of the source gas cylinder 44 is adjusted to a predetermined pressure by the regulator 48 will be described using the flowchart of Figure 7 together with Figure 1.

[0038] The control unit 76 is configured to be able to execute a default flow rate calculation mode for calculating a default flow rate, and executes the following operations when the default flow rate calculation mode is executed.

[0039] (Source gas measurement) The supply pressure of the source gas cylinder 44 is adjusted to a predetermined pressure by the regulator 48. The control unit 76 sets the supply flow rate of the dilution gas from the dilution gas cylinder 46 to zero, and causes the undiluted source gas to flow through the collection flow path 26 at a predetermined flow rate for a certain period of time to collect the target components in the source gas in the collection tube 14. Thereafter, the collected target components are guided by the carrier gas to the detector 20, and the detector 20 obtains a measurement value A0 (step 201).

[0040] (First calibration gas measurement) With the supply pressure of the source gas cylinder 44 adjusted to a predetermined pressure, the control unit 76 controls the supply flow rate of the dilution gas to V1 using the flow controller 70 to prepare a first calibration gas having a first target component concentration. Then, the control unit 76 causes the prepared first calibration gas to flow through the collection flow path 26 at a predetermined flow rate for a certain period of time to collect the target component in the first calibration gas in the collection tube 14, and then guides the collected target component to the detector 20 using the carrier gas, and the detector 20 obtains a measurement value A1 (step 202).

[0041] The control unit 76 calculates the flow rate V0 (predetermined flow rate) of the source gas when the supply pressure of the source gas cylinder 44 is adjusted to a predetermined pressure by substituting the supply flow rate V1 of the dilution gas in the first calibration gas measurement and the respective measurement values ​​A0 and A1 of the source gas measurement and the first calibration gas measurement into the following equation (1) (step 203). V0=V1(A1 / (A0-A1)) (1) The control unit 76 stores the value of the predetermined flow rate V0 calculated using the above formula (1) in the flow rate storage unit 78.

[0042] Here, the above formula (1) is derived from the following formula (2) which theoretically holds between the measured values ​​A0 and A1, the predetermined flow rate V0, and the supply flow rate V1. A1=A0·(V0 / (V0+V1)) (2)

[0043] FIG. 8 is a flowchart showing another example of the default flow rate calculation operation.

[0044] In this example, the default flow rate calculation operation involves performing a second calibration gas measurement (described later) instead of the source gas measurement. That is, the first calibration gas measurement (step 301) described above and a second calibration gas measurement (step 302) described later are performed, and the default flow rate V0 is calculated using the measurements obtained in these measurements (step 303).

[0045] (2nd calibration gas measurement) After the first calibration gas measurement (step 301) is completed, the control unit 76 controls the supply flow rate of the dilution gas to V2 using the pressure controller 70 while the supply pressure of the source gas cylinder 44 is adjusted to a predetermined pressure, to prepare a second calibration gas having a second target component concentration. Then, the control unit 76 flows the prepared second calibration gas through the collection flow path 26 at a predetermined flow rate for a certain period of time to collect the target component in the second calibration gas in the collection tube 14, and then guides the collected target component to the detector 20 using the carrier gas, and the detector 20 obtains a measurement value A2 (step 302).

[0046] The control unit 76 calculates the flow rate V0 (predetermined flow rate) of the source gas when the supply pressure of the source gas cylinder 44 is adjusted to a predetermined pressure by substituting the supply flow rates V1, V2 of the dilution gas in the first calibration gas measurement and the second calibration gas measurement and the measurement values ​​A1, A2 of each measurement into the following equation (3) (step 303). V0=(A1V1-A2V2) / (A2-A1) (3) The control unit 76 stores the value of the predetermined flow rate V0 calculated using the above formula (3) in the flow rate storage unit 78.

[0047] Here, the above formula (3) is derived as follows.

[0048] If the measurement value obtained by supplying only the source gas to the measurement unit 2 is A0, the measurement value A1 obtained in the above-mentioned first calibration gas measurement can be expressed as the following equation (2) using A0, the predetermined flow rate V0, and the supply flow rate V1. A1=A0·(V0 / (V0+V1)) (4) This equation (4) is the same as the equation (2) above. Similarly, the measured value A2 obtained in the above-mentioned second calibration gas measurement can be expressed as the following equation (5) using A0, the predetermined flow rate V0, and the supply flow rate V2. A2=A0·(V0 / (V0+V2)) (5)

[0049] If V0 is rearranged to eliminate A0 from the above equations (4) and (5), the above equation (3) is obtained. That is, the flow rate V0 of the source gas when the supply pressure of the source gas cylinder 44 is adjusted to a predetermined pressure can be obtained by calculation using the supply flow rates V1 and V2 of the dilution gas in the two measurements of the first calibration gas measurement and the second calibration gas measurement, and the measured values ​​A1 and A2.

[0050] The embodiment described above is merely one example of the gas analysis system and calibration gas supply method according to the present invention. The gas analysis system and calibration gas supply method according to the present invention are embodied as follows.

[0051] In one embodiment of the gas analysis system according to the present invention, a measuring unit for measuring the concentration of a target component in a gas; a calibration gas supply unit for supplying a calibration gas used to calibrate the measurement value of the measurement unit to the measurement unit; a control unit that controls operations of the measurement unit and the calibration gas supply unit, The calibration gas supply unit a source gas cylinder for supplying a source gas containing the target component at a known concentration; a dilution gas cylinder for supplying a dilution gas for diluting the source gas; a confluence unit that combines the source gas supplied from the source gas cylinder and the dilution gas supplied from the dilution gas cylinder to create the calibration gas; a regulator provided between the source gas cylinder and the junction for adjusting the supply pressure of the source gas supplied from the source gas cylinder to the junction; a flow rate adjusting mechanism provided between the dilution gas cylinder and the junction for controlling a flow rate of the dilution gas supplied from the dilution gas cylinder to the junction, wherein the supply flow rate of the source gas from the source gas cylinder is adjusted only by the regulator; the control unit is configured, when supplying the calibration gas from the calibration gas supply unit to the measurement unit, to adjust the concentration of the target component in the calibration gas to the target concentration only by the flow rate adjustment mechanism based on the supply pressure of the source gas fixed at the predetermined pressure, while the supply pressure of the source gas is fixed at the predetermined pressure by the regulator, the predetermined pressure being unrelated to the target concentration of the target component in the calibration gas; The gas analyzer is configured to extract only the flow rate necessary for analysis from the calibration gas adjusted to the target concentration at the confluence section and use it for measurement in the measurement section.

[0052] In a first aspect of one embodiment of the gas analysis system according to the present invention, the gas analysis system further includes a flow rate storage unit that stores, as a predetermined flow rate V0, a ​​supply flow rate of the source gas to the junction when a supply pressure of the source gas from the source gas cylinder is the predetermined pressure, The control unit is configured to calculate, when supplying the calibration gas from the calibration gas supply unit to the measurement unit, the supply flow rate of the dilution gas required to adjust the concentration of the target component in the calibration gas to the target concentration based on the predetermined flow rate V0 stored in the flow rate memory unit, and to supply the dilution gas at the calculated flow rate using the flow rate adjustment mechanism.

[0053] In a second aspect of the embodiment of the gas analysis system according to the present invention, when a preset flow rate calculation mode for calculating the preset flow rate V0 is executed, the control unit: a source gas measuring step of setting the supply flow rate of the dilution gas from the dilution gas cylinder to the junction part to 0 while the supply pressure of the source gas is fixed at the predetermined pressure, and acquiring a measurement value A0 of the measurement part when the source gas is supplied to the measurement part at the predetermined flow rate; a first calibration gas measurement step of adjusting the supply flow rate of the dilution gas from the dilution gas cylinder to the junction to a first flow rate V1 while the supply pressure of the source gas is fixed at the predetermined pressure, to prepare a first calibration gas, and acquiring a measurement value A1 of the measurement unit when the first calibration gas is supplied to the measurement unit at the predetermined flow rate; After the source gas measurement step and the first calibration gas measurement step are completed, the predetermined flow rate V0 is set as follows: V0=V1(A1 / (A0-A1)) and a calculation step of calculating using The flow rate storage unit is configured to store the predetermined flow rate V0 calculated in the calculation step. Note that this second aspect can be combined with the above-described first aspect.

[0054] In a third aspect of the embodiment of the gas analysis system according to the present invention, when a preset flow rate calculation mode for calculating the preset flow rate V0 is executed, the control unit: a first calibration gas measurement step of adjusting the supply flow rate of the dilution gas from the dilution gas cylinder to the junction to a first flow rate V1 while the supply pressure of the source gas is fixed at the predetermined pressure, to prepare a first calibration gas, and acquiring a measurement value A1 of the measurement unit when the first calibration gas is supplied to the measurement unit at the predetermined flow rate; a second calibration gas measurement step of adjusting the supply flow rate of the dilution gas from the dilution gas cylinder to the junction to a second flow rate V2 while the supply pressure of the source gas is fixed at the predetermined pressure, to prepare a second calibration gas, and acquiring a measurement value A2 of the measurement unit when the second calibration gas is supplied to the measurement unit at the predetermined flow rate; After the first calibration gas measurement step and the second calibration gas measurement step are completed, the predetermined flow rate V0 is set as follows: V0 = (A1V1-A2V2) / (A2-A1) and a calculation step of calculating using The flow rate storage unit is configured to store the predetermined flow rate V0 calculated in the calculation step. This third aspect can be combined with the first aspect.

[0055] In a fourth aspect of an embodiment of the gas analysis system according to the present invention, the calibration gas supply unit includes a resistance tube provided downstream of the regulator, and the gas analysis system includes a heater element for heating the resistance tube, thereby suppressing adsorption of the target component in the source gas within the resistance tube. This third aspect can be combined with the first aspect and / or any of the second and third aspects.

[0056] In the fourth aspect, when the measurement unit is a gas chromatograph equipped with a separation column for separating a measurement target component in a gas from other components and a column oven for accommodating the separation column and controlling the temperature of the separation column at a predetermined temperature, the resistance tube of the calibration gas supply unit can be accommodated in the column oven as the heater element. This allows the column oven constituting the gas chromatograph to function as a heater element for heating the resistance tube, eliminating the need to provide a new heater element.

[0057] One embodiment of a calibration gas supply method according to the present invention is a calibration gas supply method comprising: generating a calibration gas by joining a source gas containing a target component at a known concentration and a dilution gas for diluting the source gas at a joining section; and supplying the calibration gas to a measurement section for measuring the concentration of the target component in the gas, the method comprising: a source gas supply step of supplying the source gas to the confluence part while fixing the supply pressure of the source gas from a source gas cylinder that supplies the source gas at a predetermined pressure only by a regulator; a flow rate determining step of determining a required flow rate of the dilution gas for adjusting the concentration of the target component in the calibration gas produced at the junction to a target concentration based on the supply pressure of the source gas from the source gas cylinder fixed to the predetermined pressure; a flow rate control step of controlling the supply flow rate of the dilution gas from the dilution gas cylinder by a flow rate adjustment mechanism so that the flow rate of the dilution gas supplied from the dilution gas cylinder to the junction becomes the required flow rate calculated in the flow rate calculation step; and a calibration gas extraction step of extracting a predetermined flow rate of the calibration gas in which the concentration of the target component has been adjusted to the target concentration at the confluence section and using the gas for measurement in the measurement section.

[0058] In a first aspect of one embodiment of the calibration gas supply method according to the present invention, the calibration gas supply method includes, before the source gas supply step, a predetermined flow rate calculation step of calculating a supply flow rate of the source gas to the junction as a predetermined flow rate V0 when the supply pressure of the source gas from the source gas cylinder is the predetermined pressure; a flow rate storage step of storing the predetermined flow rate calculated in the predetermined flow rate calculation step, In the flow rate determining step, the required flow rate is determined using the predetermined flow rate V0.

[0059] In the first aspect, The predetermined flow rate calculation step includes: a source gas measuring step of setting the supply flow rate of the dilution gas from the dilution gas cylinder to the junction part to 0 while fixing the supply pressure of the source gas at the predetermined pressure, and acquiring a measurement value A0 of the measurement part when the source gas is supplied to the measurement part at the predetermined flow rate; a first calibration gas measurement step of adjusting the supply flow rate of the dilution gas from the dilution gas cylinder to the junction to a first flow rate V1 while fixing the supply pressure of the source gas at the predetermined pressure, to prepare a first calibration gas, and acquiring a measurement value A1 of the measurement unit when the first calibration gas is supplied to the measurement unit at the predetermined flow rate; After the source gas measurement step and the first calibration gas measurement step are completed, the predetermined flow rate V0 is set as follows: V0=V1(A1 / (A0-A1)) and a calculation step of calculating using:

[0060] In addition, in the first aspect, The predetermined flow rate calculation step includes: a first calibration gas measurement step of adjusting the supply flow rate of the dilution gas from the dilution gas cylinder to the junction to a first flow rate V1 while fixing the supply pressure of the source gas at the predetermined pressure, to prepare a first calibration gas, and acquiring a measurement value A1 of the measurement unit when the first calibration gas is supplied to the measurement unit at the predetermined flow rate; a second calibration gas measurement step of adjusting the supply flow rate of the dilution gas from the dilution gas cylinder to the junction to a second flow rate V2 while fixing the supply pressure of the source gas at the predetermined pressure, to prepare a second calibration gas, and acquiring a measurement value A2 of the measurement unit when the second calibration gas is supplied to the measurement unit at the predetermined flow rate; After the first calibration gas measurement step and the second calibration gas measurement step are completed, the predetermined flow rate V0 is set as follows: V0 = (A1V1-A2V2) / (A2-A1) and a calculation step of calculating using: [Explanation of symbols]

[0061] 1 Gas analysis system 2 Measuring part 4. Calibration gas supply unit 6. Sample gas flow path 8 Calibration gas flow path 10 Branch 12 Multiport valve 14 Collection tube 16 First separation column 18 Second Separation Column 20 detectors 22 Suction pump 24 Inlet channel 26 Collection channel 28 First separation channel 30 Second separation channel 32 Suction channel 34 First carrier gas flow path 36 Second carrier gas flow path 38 Drain channel 40 Discharge flow path 42, 56, 60, 66 Stop valve 44 Source gas cylinder 46 Dilution gas cylinder 48,68 Regulator 50 source gas flow path 52 Dilution channel 54 Non-dilution flow path 58,62,72 resistance tube 64 Purge channel 69 Dilution gas flow path 70 Pressure Controller 74 Junction 76 Control Unit 78 Flow rate storage section

Claims

1. a measuring unit for measuring the concentration of a target component in a gas; a calibration gas supply unit for supplying a calibration gas used to calibrate the measurement value of the measurement unit to the measurement unit; a control unit that controls operations of the measurement unit and the calibration gas supply unit, The calibration gas supply unit a source gas cylinder for supplying a source gas containing the target component at a known concentration; a dilution gas cylinder for supplying a dilution gas for diluting the source gas; a confluence unit that combines the source gas supplied from the source gas cylinder and the dilution gas supplied from the dilution gas cylinder to create the calibration gas; a regulator provided between the source gas cylinder and the junction for adjusting the supply pressure of the source gas supplied from the source gas cylinder to the junction; a flow rate adjusting mechanism provided between the dilution gas cylinder and the junction for controlling a flow rate of the dilution gas supplied from the dilution gas cylinder to the junction, wherein the supply flow rate of the source gas from the source gas cylinder is adjusted only by the regulator; the control unit is configured, when supplying the calibration gas from the calibration gas supply unit to the measurement unit, to adjust the concentration of the target component in the calibration gas to the target concentration only by the flow rate adjustment mechanism based on the supply pressure of the source gas fixed at the predetermined pressure, while the supply pressure of the source gas is fixed at the predetermined pressure by the regulator, the predetermined pressure being unrelated to the target concentration of the target component in the calibration gas; The gas analyzer is configured to extract only the flow rate necessary for analysis from the calibration gas adjusted to the target concentration at the confluence section and use it for measurement in the measurement section.

2. The supply flow rate of the source gas to the confluence when the supply pressure of the source gas from the source gas cylinder is the predetermined pressure is defined as a predetermined flow rate V ０ a flow rate storage unit for storing the flow rate as The control unit calculates the supply flow rate of the dilution gas necessary to make the concentration of the target component in the calibration gas the target concentration when the calibration gas is supplied from the calibration gas supply unit to the measurement unit by the predetermined flow rate V stored in the flow rate memory unit. ０ 2. The gas analyzer according to claim 1, wherein the flow rate of the dilution gas is calculated based on the calculated flow rate by the flow rate adjusting mechanism.

3. The control unit determines the predetermined flow rate V ０ When the default flow calculation mode for finding A measured value A of the measurement unit when the supply pressure of the source gas is fixed at the predetermined pressure, the supply flow rate of the dilution gas from the dilution gas cylinder to the confluence unit is set to 0, and the source gas is supplied to the measurement unit at a predetermined flow rate. ０ a source gas measurement step for obtaining a With the supply pressure of the source gas fixed at the predetermined pressure, the supply flow rate of the dilution gas from the dilution gas cylinder to the junction is set to a first flow rate V １ and a first calibration gas is prepared by adjusting the flow rate of the first calibration gas to the measurement unit. １ a first calibration gas measurement step for obtaining a After the source gas measurement step and the first calibration gas measurement step are completed, the predetermined flow rate V ０ of, V ０ =V １ (A) １ / (A ０ -A １ )) and a calculation step of calculating using The flow rate storage unit stores the predetermined flow rate V calculated in the calculation step. ０ 3. The gas analyzer of claim 2, configured to store:

4. The control unit determines the predetermined flow rate V ０ When the default flow calculation mode for finding With the supply pressure of the source gas fixed at the predetermined pressure, the supply flow rate of the dilution gas from the dilution gas cylinder to the junction is set to a first flow rate V １ and a first calibration gas is prepared by adjusting the flow rate of the first calibration gas to a predetermined value. １ a first calibration gas measurement step for obtaining a With the supply pressure of the source gas fixed at the predetermined pressure, the supply flow rate of the dilution gas from the dilution gas cylinder to the junction is set to a second flow rate V ２ and a second calibration gas is prepared by adjusting the flow rate of the second calibration gas to the measurement unit. ２ a second calibration gas measurement step for obtaining a second calibration gas; After the first calibration gas measurement step and the second calibration gas measurement step are completed, the predetermined flow rate V ０ of, V ０ =(A １ V １ -A ２ V ２ ) / (A ２ -A １ ) and a calculation step of calculating using The flow rate storage unit stores the predetermined flow rate V calculated in the calculation step. ０ 3. The gas analyzer of claim 2, configured to store:

5. the calibration gas supply unit includes a resistance tube provided downstream of the regulator; The gas analyzer according to claim 1 , further comprising a heater element for heating the resistance tube.

6. the measurement unit is a gas chromatograph including a separation column for separating a measurement target component in a gas from other components, and a column oven for accommodating the separation column therein and controlling the temperature of the separation column to a predetermined temperature; 6. The gas analyzer according to claim 5, wherein the resistance tube of the calibration gas supply unit is housed in the column oven serving as the heater element.

7. 1. A calibration gas supply method comprising: preparing a calibration gas by combining a source gas containing a target component at a known concentration and a dilution gas for diluting the source gas at a confluence portion; and supplying the calibration gas to a measurement portion for measuring the concentration of the target component in the gas, a source gas supply step of supplying the source gas to the confluence part while fixing the supply pressure of the source gas from a source gas cylinder that supplies the source gas at a predetermined pressure only by a regulator; a flow rate determining step of determining a required flow rate of the dilution gas for adjusting the concentration of the target component in the calibration gas produced at the junction to a target concentration based on the supply pressure of the source gas from the source gas cylinder fixed to the predetermined pressure; a flow rate control step of controlling the supply flow rate of the dilution gas from the dilution gas cylinder by a flow rate adjustment mechanism so that the flow rate of the dilution gas supplied from the dilution gas cylinder to the junction becomes the required flow rate calculated in the flow rate calculation step; a calibration gas extraction step of extracting a predetermined flow rate of the calibration gas in which the concentration of the target component has been adjusted to the target concentration at the confluence part and using the extracted flow rate for measurement in the measurement part.

8. Before the source gas supply step, the supply flow rate of the source gas to the confluence when the supply pressure of the source gas from the source gas cylinder is the predetermined pressure is set to a predetermined flow rate V ０ A default flow rate calculation step: a flow rate storage step of storing the predetermined flow rate calculated in the predetermined flow rate calculation step, In the flow rate determining step, the predetermined flow rate V ０ 8. The calibration gas supply method of claim 7, wherein the required flow rate is determined using:

9. The predetermined flow rate calculation step includes: A measured value A of the measurement unit when the supply pressure of the source gas is fixed at the predetermined pressure, the supply flow rate of the dilution gas from the dilution gas cylinder to the confluence unit is set to 0, and the source gas is supplied to the measurement unit at the predetermined flow rate. ０ a source gas measurement step for obtaining a With the supply pressure of the source gas fixed at the predetermined pressure, the supply flow rate of the dilution gas from the dilution gas cylinder to the junction is set to a first flow rate V １ and a first calibration gas is prepared by adjusting the flow rate of the first calibration gas to the measurement unit. １ a first calibration gas measurement step for obtaining a After the source gas measurement step and the first calibration gas measurement step are completed, the predetermined flow rate V ０ of, V ０ =V １ (A) １ / (A ０ -A １ )) 9. The calibration gas supply method according to claim 8, further comprising a calculation step of calculating using:

10. The predetermined flow rate calculation step includes: With the supply pressure of the source gas fixed at the predetermined pressure, the supply flow rate of the dilution gas from the dilution gas cylinder to the junction is set to a first flow rate V １ and a first calibration gas is prepared by adjusting the flow rate of the first calibration gas to the measurement unit. １ a first calibration gas measurement step for obtaining a With the supply pressure of the source gas fixed at the predetermined pressure, the supply flow rate of the dilution gas from the dilution gas cylinder to the junction is set to a second flow rate V ２ and a second calibration gas is prepared by adjusting the flow rate of the second calibration gas to the measurement unit. ２ a second calibration gas measurement step for obtaining a second calibration gas; After the first calibration gas measurement step and the second calibration gas measurement step are completed, the predetermined flow rate V ０ of, V ０ =(A １ V １ -A ２ V ２ ) / (A ２ -A １ ) 9. The calibration gas supply method according to claim 8, further comprising a calculation step of calculating using:

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