JP6281450B2 - Gas chromatograph and flow control device used therefor - Google Patents

Description

  The present invention relates to a gas chromatograph that performs analysis by supplying a carrier gas and a sample gas into a column from a sample introduction section, and a flow rate control device used therefor.

  In a gas chromatograph, a carrier gas and a sample gas are supplied into a column from a sample introduction part, and sample components are separated in the process of passing the carrier gas through the column. The carrier gas is supplied from the gas supply channel to the sample introduction unit by the flow rate control device, mixed with the sample gas in the sample introduction unit, and then introduced into the column from the column inlet.

  As an example of a method for introducing a carrier gas into a column from the column inlet, a split introduction method is known. When the carrier gas is introduced into the column from the column inlet using the split introduction method, a part of the sample gas is discharged to the outside together with the carrier gas through the split flow path communicating with the sample introduction unit. The split flow path is provided with a split valve, and the gas pressure (inlet pressure) at the column inlet can be controlled by adjusting the flow rate of the gas discharged from the split flow path using the split valve. it can.

  The inlet pressure at the column inlet is detected by an inlet pressure sensor. The flow rate of the carrier gas supplied from the gas supply channel to the sample introduction unit is controlled by a full flow valve provided in the gas supply channel based on the inlet pressure detected by the inlet pressure sensor. That is, the flow rate of the carrier gas is adjusted by the full flow valve so that the inlet pressure becomes a predetermined set pressure (see, for example, Patent Document 1 below).

Japanese Patent No. 3669402

  However, in the configuration in which the flow rate of the carrier gas is controlled based on the inlet pressure as described above, there is a problem that it is difficult to adjust the flow rate of the carrier gas when the set pressure of the inlet pressure is low. That is, when the full flow valve is opened at the time of startup, it is difficult to suppress the increase in the inlet pressure, and the inlet pressure increases to a relatively high pressure. Therefore, when the set pressure of the inlet pressure is low, the inlet pressure exceeds the set pressure, and so-called overshoot may occur. Also, if the carrier gas is supplied at an excessive flow rate at once, the filler such as glass wool provided in the sample introduction part moves, and the reproducibility of the analysis may be deteriorated.

  On the other hand, some gas chromatographs have a carrier gas saving function that can reduce the consumption of carrier gas. In this type of gas chromatograph, the consumption of the carrier gas can be reduced by suppressing the flow rate of the carrier gas discharged from the split flow path after the end of the analysis. After that, when the operation of the gas chromatograph is stopped, the carrier gas is discharged, so that the inside of the sample introduction section becomes atmospheric pressure. When the gas chromatograph is started next time, the carrier is placed inside the sample introduction section under atmospheric pressure. Gas is supplied, and the flow rate of the carrier gas is adjusted by the full flow valve so that the inlet pressure becomes a predetermined set pressure.

  At this time, if the carrier gas saving function is not released, the carrier gas is supplied into the sample introduction portion while the flow rate of the carrier gas discharged from the split flow path is small. When the flow rate of the carrier gas discharged from the split flow path is small, the flow rate of the carrier gas supplied into the sample introduction unit is also small. In this case, there is a problem that the start-up time until the inlet pressure reaches the threshold value becomes long because the flow rate of the carrier gas is small even though the set pressure of the inlet pressure is high.

  Thus, when the starting time of the gas chromatograph becomes long, there is a possibility that it is erroneously determined that a gas leak has occurred based on the slow increase rate of the inlet pressure. In order to avoid such a problem, the carrier gas must be supplied at a flow rate that is high enough to prevent erroneous determination, even though the carrier gas saving function is a function for reducing the consumption of carrier gas. Therefore, there is a problem that the consumption of the carrier gas cannot be reduced sufficiently.

  The present invention has been made in view of the above circumstances, and provides a gas chromatograph capable of preventing the carrier gas from being supplied into the sample introduction section at an excessive flow rate at the time of start-up, and a flow control device used therefor The purpose is to do. Moreover, an object of this invention is to provide the gas chromatograph which can shorten starting time, and the flow control apparatus used for this.

  The gas chromatograph according to the present invention includes a sample introduction unit, a gas supply channel, a column, a split channel, a total flow rate detection unit, an inlet pressure detection unit, and a total flow rate control unit. The gas supply channel supplies a carrier gas to the sample introduction unit. A carrier gas and a sample gas are introduced into the column from the sample introduction section through a column inlet. The split channel discharges a part of the gas in the sample introduction part. The total flow rate detection unit detects the flow rate of the carrier gas in the gas supply channel. The inlet pressure detector detects an inlet pressure at the column inlet. The total flow rate control unit controls the flow rate of the carrier gas in the gas supply channel. The total flow control unit controls the flow rate of the carrier gas so that the flow rate of the carrier gas detected by the total flow rate detection unit becomes a predetermined temporarily set flow rate at the time of startup, and is detected by the inlet pressure detection unit After the inlet pressure reaches the threshold value, the carrier gas is controlled to the set flow rate while maintaining the inlet pressure at the set pressure.

  According to such a configuration, the carrier gas flow rate is determined based on the carrier gas flow rate detected by the total flow rate detection unit until the inlet pressure detected by the inlet pressure detection unit reaches a threshold value at startup. Control is performed so as to obtain a predetermined temporarily set flow rate. Therefore, if the temporarily set flow rate of the carrier gas is appropriately set, it is possible to prevent the carrier gas from being supplied into the sample introduction unit at an excessive flow rate at the time of startup.

  Thus, unlike the configuration in which the flow rate of the carrier gas is controlled based on the inlet pressure, it is possible to prevent overshoot even when the set pressure of the inlet pressure is low. In addition, since it is possible to prevent the carrier gas from being supplied at an excessive flow rate at one time, the packing material such as glass wool provided in the sample introduction portion does not move, and the reproducibility of the analysis deteriorates. Can be prevented.

  Furthermore, if the temporarily set flow rate of the carrier gas is appropriately set, it is possible to prevent the occurrence of a state where the flow rate of the carrier gas is low even though the set pressure of the inlet pressure is high. Thereby, the starting time until the inlet pressure reaches the threshold value can be shortened.

  The gas chromatograph may further include a temporarily set flow rate calculation unit that calculates the temporarily set flow rate based on the set pressure.

  According to such a configuration, an appropriate temporarily set flow rate of the carrier gas can be calculated based on the set pressure of the inlet pressure. Accordingly, it is possible to reliably prevent the carrier gas from being supplied into the sample introduction portion at an excessive flow rate at the time of startup, and to effectively shorten the time until the inlet pressure reaches the threshold value.

  The temporarily set flow rate calculation unit is configured such that at least the volume of a constant region downstream from the total flow rate valve including at least the internal space of the sample introduction unit and the inlet pressure detected by the inlet pressure detection unit from the start-up are the threshold values. The temporarily set flow rate may be calculated on the basis of the start-up time until it reaches.

  According to such a configuration, it is possible to calculate a more appropriate temporarily set flow rate by calculating the temporarily set flow rate of the carrier gas using not only the set pressure of the inlet pressure but also the volume and the starting time.

  The gas chromatograph may further include a volume setting receiving unit that receives the setting of the volume. In this case, the temporarily set flow rate calculation unit may calculate the temporarily set flow rate based on the set volume.

  According to such a configuration, it is possible to set an arbitrary volume and calculate an optimal carrier gas temporarily set flow rate in the volume. Therefore, the carrier gas can be supplied into the sample introduction unit at an optimum flow rate at the time of startup according to the type of the sample introduction unit to be used.

  The gas chromatograph may further include an activation time setting receiving unit that receives the setting of the activation time. In this case, the temporarily set flow rate calculation unit may calculate the temporarily set flow rate based on the set activation time.

  According to such a configuration, it is possible to set an arbitrary startup time and calculate an optimal temporarily set flow rate of the carrier gas at the startup time. Therefore, the carrier gas can be supplied into the sample introduction portion at an optimum flow rate at the time of start-up regardless of the length of the start-up time.

  The gas chromatograph further includes a volume calculator that calculates the volume based on a change in inlet pressure detected by the inlet pressure detector when the flow rate of the carrier gas is controlled by the total flow controller. Also good.

  According to such a configuration, it is possible to calculate the volume of a certain region downstream of the entire flow rate valve and calculate the temporarily set flow rate of the carrier gas using the volume. Therefore, even when the volume is unknown, the volume can be calculated to calculate an appropriate temporarily set flow rate of the carrier gas.

  The gas chromatograph may further include an atmospheric pressure sensor that detects atmospheric pressure. In this case, the temporarily set flow rate calculation unit may calculate the temporarily set flow rate based on the atmospheric pressure detected by the atmospheric pressure sensor.

  According to such a configuration, it is possible to detect a different atmospheric pressure depending on the use environment of the apparatus by the atmospheric pressure sensor, and more appropriately calculate the temporarily set flow rate of the carrier gas using the atmospheric pressure. Thereby, regardless of the usage environment of the apparatus, the carrier gas can be supplied into the sample introduction section at an optimum flow rate at the time of startup.

  The volume calculation unit may calculate the volume based on an atmospheric pressure detected by the atmospheric pressure sensor.

  According to such a configuration, different atmospheric pressures are detected by the atmospheric pressure sensor depending on the use environment of the apparatus, and the volume of a certain region downstream of the entire flow rate valve is appropriately calculated using the atmospheric pressure. Can do. Thereby, the temporarily set flow rate of the carrier gas can be appropriately calculated using the calculated volume regardless of the use environment of the apparatus.

  A flow rate control device according to the present invention is a flow rate control device for controlling the flow rates of a carrier gas and a sample gas introduced into a column from a sample introduction unit via a column inlet, and includes a gas supply channel, a split flow A path, a total flow rate detection unit, an inlet pressure detection unit, and a total flow rate control unit. The gas supply channel supplies a carrier gas to the sample introduction unit. The split channel discharges a part of the gas in the sample introduction part. The total flow rate detection unit detects the flow rate of the carrier gas in the gas supply channel. The inlet pressure detector detects an inlet pressure at the column inlet. The total flow rate control unit controls the flow rate of the carrier gas in the gas supply channel. The total flow control unit controls the flow rate of the carrier gas so that the flow rate of the carrier gas detected by the total flow rate detection unit becomes a predetermined temporarily set flow rate at the time of startup, and is detected by the inlet pressure detection unit After the inlet pressure reaches the threshold value, the carrier gas is controlled to the set flow rate while the inlet pressure is maintained at a predetermined set pressure.

  According to the present invention, by appropriately setting the temporarily set flow rate of the carrier gas, it is possible to prevent the carrier gas from being supplied into the sample introduction unit at an excessive flow rate during startup. Further, according to the present invention, it is possible to prevent the occurrence of a state in which the flow rate of the carrier gas is low even though the set pressure of the inlet pressure is high, so that the inlet pressure reaches the threshold value. Can be shortened.

It is the schematic which showed the structural example of the gas chromatograph which concerns on one Embodiment of this invention. It is the block diagram which showed an example of the electrical constitution in the gas chromatograph of FIG. It is the flowchart which showed an example of the process by the control part at the time of starting. It is the figure which showed the time-dependent change of the inlet pressure detected by an inlet pressure sensor, and has shown the case where this invention is not applied. It is the figure which showed the time-dependent change of the inlet pressure detected by an inlet pressure sensor, and has shown an example in case this invention is applied. It is the figure which showed the time-dependent change of the inlet pressure detected by an inlet pressure sensor, and has shown another example in case this invention is applied. It is the figure which showed the time-dependent change of the inlet pressure detected by an inlet pressure sensor, and has shown another example in case this invention is applied.

  FIG. 1 is a schematic diagram showing a configuration example of a gas chromatograph according to an embodiment of the present invention. This gas chromatograph is for performing analysis by supplying a sample gas together with a carrier gas into the column 1. In addition to the column 1, a sample introduction unit 2, a gas supply channel 3, a split channel 4, A purge flow path 5 and a detector 6 are provided.

  The column 1 is composed of, for example, a capillary column, and is heated in a column oven during analysis. The carrier gas is introduced into the column 1 from the sample introduction unit 2 through the column inlet 11 together with the sample gas. Sample components contained in the sample gas are separated in the process of passing through the column 1 and detected by the detector 6. The detector 6 can be composed of various detectors such as a flame ionization detector (FID).

  The sample introduction unit 2 is for introducing a carrier gas and a sample gas into the column 1 from the column inlet 11, and its internal space constitutes a sample vaporization chamber 21. A liquid sample is injected into the sample vaporizing chamber 21, and the sample vaporized in the sample vaporizing chamber 21 is introduced into the column 1 from the column inlet 11 together with the carrier gas. A gas supply channel 3, a split channel 4 and a purge channel 5 communicate with the sample vaporizing chamber 21.

  The gas supply channel 3 is a channel for supplying a carrier gas into the sample vaporization chamber 21 of the sample introduction unit 2. The split flow path 4 allows a part of the gas (mixed gas of the carrier gas and the sample gas) in the sample vaporizing chamber 21 when the carrier gas and the sample gas are introduced into the column 1 from the column inlet 11 by the split introduction method. It is a flow path for discharging to the outside at a predetermined split ratio. The purge channel 5 is a channel for discharging an undesired component generated from a septum or the like to the outside.

  In the gas supply flow path 3, for example, a supply pressure sensor 31, a differential pressure sensor 32, and a total flow valve 33 are provided. The supply pressure sensor 31 detects the pressure in the gas supply flow path 3 on the upstream side of the total flow valve 33. The differential pressure sensor 32 is a total flow rate detection unit that detects the flow rate of the carrier gas in the gas supply channel 3 based on the differential pressure upstream and downstream of the differential pressure sensor 32. The total flow valve 33 opens and closes the gas supply channel 3 to open a state between the open state in which the carrier gas is supplied from the gas supply channel 3 to the sample introduction unit 2 and the closed state in which the supply of the carrier gas is stopped. Thus, the flow rate of the carrier gas in the gas supply channel 3 can be arbitrarily adjusted.

  For example, a split valve 41 is provided in the split flow path 4. The split valve 41 is opened and closed by opening and closing the split flow path 4 and closed when gas discharge from the sample introduction section 2 is stopped via the split flow path 4. Between them, the flow rate of the gas in the split flow path 4 can be arbitrarily adjusted. In the present embodiment, not only can the analysis be performed in the split mode by opening the split valve 41, but also the analysis can be performed in the splitless mode by closing the split valve 41.

  In the purge flow path 5, for example, an inlet pressure sensor 51, a purge valve 52, and a purge pressure sensor 53 are provided. The inlet pressure sensor 51 is provided on the upstream side (the sample introduction part 2 side) of the purge valve 52, and detects the pressure of the gas in the sample vaporizing chamber 21, that is, the pressure of the gas at the column inlet 11 (inlet pressure). It is a detection unit. The purge valve 52 opens and closes the purge flow path 5 to open the gas from the sample introduction section 2 through the purge flow path 5, and the closed state in which the gas discharge from the sample introduction section 2 is stopped. Between them, the flow rate of the gas in the purge flow path 5 can be arbitrarily adjusted. The purge pressure sensor 53 detects the pressure in the purge flow path 5 on the downstream side of the purge valve 52.

  Since the purge flow path 5 has a small gas flow rate and gas flows at a substantially constant flow rate, pressure loss is unlikely to occur. Therefore, by providing an inlet pressure sensor 51 in the purge flow path 5, the inlet pressure can be further increased. It can be detected accurately. However, the inlet pressure sensor 51 is not limited to the purge flow path 5, and may be provided in any other portion (for example, the split flow path 4) communicating with the column inlet 11.

  FIG. 2 is a block diagram showing an example of an electrical configuration in the gas chromatograph of FIG. The operation of this gas chromatograph is controlled by a control unit 7 including, for example, a CPU (Central Processing Unit). In addition to the control unit 7, the gas supply flow path 3, the split flow path 4, the purge flow path 5, the supply pressure sensor 31, the differential pressure sensor 32, the total flow valve 33, the split valve 41, the inlet pressure sensor 51, the purge valve 52, and The purge pressure sensor 53 and the like constitute a flow rate control device for controlling the flow rates of the carrier gas and the sample gas introduced from the sample introduction unit 2 through the column inlet 11 into the column 1.

  When the CPU executes the program, the control unit 7 includes a total flow control unit 71, a split flow control unit 72, a purge flow control unit 73, an inlet pressure setting reception unit 74, a volume setting reception unit 75, and an activation time setting reception unit. 76, functions as a temporarily set flow rate calculation unit 77, a volume calculation unit 78, and the like.

  The total flow control unit 71 controls the flow rate of the carrier gas in the gas supply flow path 3 by adjusting the opening of the total flow valve 33. The total flow control unit 71 can control the carrier gas to a predetermined set flow rate so that the inlet pressure becomes a predetermined set pressure with reference to the inlet pressure at the column inlet 11 detected by the inlet pressure sensor 51. Instead, when the gas chromatograph or the flow control device is started (for example, when a control start command is received), the flow rate becomes a predetermined temporarily set flow rate with reference to the flow rate of the carrier gas detected by the differential pressure sensor 32. It can also be controlled. The set flow rate is the total flow rate set as the analysis condition, and the temporary set flow rate is the total flow rate for increasing the rate of increase of the inlet pressure.

  The split flow rate control unit 72 controls the flow rate of the gas in the split flow path 4 so that the split ratio becomes a preset value by adjusting the opening of the split valve 41. Further, the purge flow rate control unit 73 controls the flow rate of the gas in the purge flow path 5 to be a preset flow rate by adjusting the opening of the purge valve 52.

  The operator can arbitrarily input various parameters such as a set value (set pressure) of the inlet pressure, a system volume, and a startup time by operating the operation unit 8. These various parameters may be input as arbitrary values, or may be arbitrarily selected from a plurality of values. The operation unit 8 can be configured with, for example, operation keys, a keyboard, or a mouse. The various parameters that are input are stored in the storage unit 9 including, for example, a RAM (Random Access Memory) or a hard disk.

  The inlet pressure setting receiving unit 74 receives the setting of the inlet pressure input by the operator using the operation unit 8 and stores the set pressure in the storage unit 9. The volume setting receiving unit 75 receives the setting of the system volume input by the operator using the operation unit 8 and stores the volume in the storage unit 9. The activation time setting accepting unit 76 accepts the activation time setting input by the operator using the operation unit 8 and stores the activation time in the storage unit 9.

  Here, the volume of the system is the volume of a certain region downstream of at least the total flow rate valve 33 including the sample vaporizing chamber 21, for example, not only the volume of the sample vaporizing chamber 21 but also the total volume in the gas supply flow path 3. The concept includes a volume downstream of the flow rate valve 33, a volume upstream of the split valve 41 in the split flow path 4, and a volume upstream of the purge valve 52 in the purge flow path 5. Further, the activation time is, for example, the time from the activation of the gas chromatograph or the flow rate control device to the arrival of a predetermined threshold, for example, about 5 to 10 seconds. preferable.

  In the present embodiment, the total flow rate control unit 71 controls the flow rate of the carrier gas so that the flow rate of the carrier gas detected by the differential pressure sensor 32 becomes a predetermined temporarily set flow rate different from the analysis conditions at the time of activation. At this time, the split valve 41 and the purge valve 52 are closed. Then, after the inlet pressure detected by the inlet pressure sensor 51 reaches the threshold value, the total flow control unit 71 keeps the inlet pressure at a predetermined set pressure so that the flow rate of the carrier gas becomes the set flow rate. Control. In this state, the split valve 41 and the purge valve 52 are opened, and control is performed according to preset analysis conditions.

  The control by the total flow control unit 71 as described above is preferably performed, for example, when the gas chromatograph or the flow control device is started in a state where the carrier gas saving function is not released. Here, the carrier gas saving function is a function for reducing the consumption amount of the carrier gas, and the flow rate of the carrier gas discharged from the split flow path 4 by reducing the opening of the split valve 41 after the analysis is finished. By suppressing, the consumption amount of carrier gas can be reduced.

  The set pressure is an inlet pressure set as an analysis condition, and is stored in advance in the storage unit 9 by the operator's setting operation as described above. The threshold value is, for example, a value or range based on the set pressure, and may be the same value as the set pressure or a different value or range. The temporarily set flow rate is calculated by the temporarily set flow rate calculation unit 77 based on the set pressure of the inlet pressure. However, the temporary set flow rate may be configured by the operator operating the operation unit 8.

The calculation method of the temporarily set flow rate by the temporarily set flow rate calculation unit 77 will be specifically described. For example, the temporarily set flow rate is calculated based on the set pressure of the inlet pressure, the system volume, and the startup time stored in the storage unit 9. be able to. Here, assuming that the volume of the system is V [mL], the startup time is T [min], and the set pressure of the inlet pressure is p [kPa], the temporarily set flow rate f [mL / min] of the carrier gas at startup is For example, it can be represented by the following formula (1).
f = p / 101.325 × V / T (1)

  In the above formula (1), the value “101.325” indicates atmospheric pressure [kPa]. The value of the atmospheric pressure is not limited to the configuration in which the fixed value as described above is used. For example, as shown in FIG. 2, the temporarily set flow rate calculation unit is based on the atmospheric pressure detected by the atmospheric pressure sensor 10. 77 may calculate the temporarily set flow rate f. In this case, in the above formula (1), the value of the atmospheric pressure detected by the atmospheric pressure sensor 10 may be used instead of the constant “101.325”.

In addition, since the inlet pressure does not always decrease to the atmospheric pressure at the time of startup, the inlet pressure is measured using the inlet pressure sensor 51 at the time of startup, and the carrier gas is temporarily measured using the actual measured value p _act of the inlet pressure. The set flow rate f may be calculated. In this case, the calculation may be performed by replacing p in the above formula (1) with (p-p _act ).

  An upper limit value is preferably set for the system volume V, and a lower limit value is preferably set for the startup time T. In addition, when the total flow rate target value during the execution of the carrier gas saving function is set to 0 [mL / min], it can be determined that there is no intention to use gas, so it is set in advance from the time of startup. It is preferable that the control is performed according to the analysis conditions.

  In the present embodiment, at the time of startup, until the inlet pressure detected by the inlet pressure sensor 51 reaches a threshold value, the carrier gas flow rate is set to a predetermined temporary value based on the carrier gas flow rate detected by the differential pressure sensor 32. The flow rate is controlled to be a set flow rate f. Therefore, if the temporarily set flow rate f of the carrier gas is appropriately set, it is possible to prevent the carrier gas from being supplied into the sample introduction unit 2 at an excessive flow rate at the time of startup.

  Thus, unlike the configuration in which the flow rate of the carrier gas is controlled based on the inlet pressure, it is possible to prevent overshoot even when the set pressure p of the inlet pressure is low. Further, since it is possible to prevent the carrier gas from being supplied at an excessive flow rate at a time, the packing material such as glass wool provided in the sample introduction unit 2 does not move, and the reproducibility of the analysis is improved. Deterioration can be prevented.

  Furthermore, if the temporarily set flow rate f of the carrier gas is appropriately set, it is possible to prevent the occurrence of a state where the flow rate of the carrier gas is low even though the set pressure p of the inlet pressure is high. . Thereby, the starting time T until the inlet pressure reaches the threshold value can be shortened. Therefore, it is possible to prevent erroneous determination that a gas leak has occurred based on the slow rise rate of the inlet pressure, so the flow rate of the carrier gas when the carrier gas save function is being executed is reduced. It can be set low, and the consumption of carrier gas can be sufficiently reduced. Moreover, since the start-up time T is shortened, it also becomes a motivation to actively use the carrier gas saving function.

  In particular, in the present embodiment, for example, by using the above formula (1), an appropriate temporary set flow rate f of the carrier gas can be calculated based on the set pressure p of the inlet pressure. When the above equation (1) is used, a more appropriate provisional flow rate f is calculated by calculating the provisional set flow rate f of the carrier gas using not only the set pressure p of the inlet pressure but also the system volume V and the startup time T. The set flow rate f can be calculated. Therefore, it is possible to reliably prevent the carrier gas from being supplied into the sample introduction unit 2 at an excessive flow rate at the time of starting, and to effectively shorten the starting time T until the inlet pressure reaches the threshold value. Can do.

  In the present embodiment, the temporarily set flow rate calculation unit 77 calculates the temporarily set flow rate f of the carrier gas based on the preset system volume V and the startup time T. As a result, an arbitrary volume V and start-up time T can be set, and an optimal carrier gas temporary set flow rate f can be calculated at the volume V and start-up time T. Therefore, regardless of the length of the startup time T, the carrier gas can be supplied into the sample introduction unit 2 at an optimum flow rate at the start-up according to the type of the sample introduction unit 2 to be used.

  Further, if the temporary flow rate f is calculated based on the atmospheric pressure detected by the atmospheric pressure sensor 10 as described above, the atmospheric pressure sensor 10 detects different atmospheric pressures depending on the use environment of the apparatus. Then, the temporarily set flow rate f of the carrier gas can be calculated more appropriately using the atmospheric pressure. Thereby, regardless of the use environment of the apparatus, the carrier gas can be supplied into the sample introduction unit 2 at an optimum flow rate at the time of startup.

  When the system volume V is known in advance, the temporary set flow rate f of the carrier gas can be calculated using the system volume V set by the operator as described above. However, since the volume V of the system may be unknown, in this embodiment, the volume V of the system can be calculated by the volume calculation unit 78. Specifically, when the operator gives an instruction to start volume measurement by operating the operation unit 8 when the analysis is not in progress, the split valve 41 and the purge valve 52 are closed. The carrier gas is supplied into the sample introduction unit 2 at a constant total flow rate F [mL / min].

At this time, if the time from the start of volume measurement until the inlet pressure increases by dp [kPa] is dt [min], the volume V of the system is expressed by the following equation (2). Therefore, the volume calculation unit 78 is based on the change in the inlet pressure detected by the inlet pressure sensor 51 when the flow rate of the carrier gas is controlled by the total flow rate control unit 71 by using the following formula (2), for example. The volume V of the system can be calculated.
V = F × 101.325 / dp × dt (2)

  In the above formula (2), the value “101.325” indicates atmospheric pressure [kPa]. The value of the atmospheric pressure is not limited to the configuration in which the fixed value as described above is used. For example, as shown in FIG. 2, the volume calculation unit 78 is based on the atmospheric pressure detected by the atmospheric pressure sensor 10. The system may be configured to calculate the volume V of the system. In this case, in the above equation (2), the value of the atmospheric pressure detected by the atmospheric pressure sensor 10 may be used instead of the constant “101.325”.

  The volume measurement as described above is preferably performed in a state where the column 1 is removed from the sample introduction unit 2. However, it is also possible to measure the volume with the column 1 attached to the sample introduction unit 2, and in this case, a virtual volume V including the volume of the gas flowing out from the column 1 must be obtained. It becomes.

  Thus, in the present embodiment, the volume V of the system on the downstream side of the total flow rate valve 33 can be calculated, and the temporarily set flow rate f of the carrier gas can be calculated using the volume V. Therefore, even if the volume V of the system is unknown, the volume V can be calculated and an appropriate temporarily set flow rate f of the carrier gas can be calculated.

  Further, if the system volume V is calculated based on the atmospheric pressure detected by the atmospheric pressure sensor 10 as described above, the atmospheric pressure sensor 10 detects different atmospheric pressures depending on the use environment of the apparatus. Then, the volume V of the system can be appropriately calculated using the atmospheric pressure. Thereby, the temporarily set flow rate f of the carrier gas can be appropriately calculated using the calculated volume V regardless of the use environment of the apparatus.

  FIG. 3 is a flowchart showing an example of processing by the control unit 7 at the time of activation. When the gas chromatograph is activated, first, the temporarily set flow rate f of the carrier gas is calculated in the manner as described above (step S101), and the total flow rate of the carrier gas is controlled to be the temporarily set flow rate f (step S101). S102). When the inlet pressure detected by the inlet pressure sensor 51 reaches a predetermined threshold value based on the set pressure p (Yes in step S103), the carrier gas is maintained while maintaining the inlet pressure at the set pressure p. Control is performed so that the total flow rate becomes the set flow rate (step S104). That is, the carrier gas total flow rate target value is switched from the temporarily set flow rate f to the set flow rate set as the analysis condition.

  4 and FIGS. 5A to 5C are diagrams showing the change over time in the inlet pressure detected by the inlet pressure sensor 51. FIG. FIG. 4 shows a case where the present invention is not applied, and FIGS. 5A to 5C show a case where the present invention is applied. In these drawings, the change in the inlet pressure with time is shown by a solid line, and the flow rate of the carrier gas is shown by a broken line in association with this.

  The example of FIG. 4 shows a case where the gas chromatograph is started in a state where the set pressure p of the inlet pressure is set to 200 [kPa] and the carrier gas saving function is not released. In this case, although the set pressure p of the inlet pressure is high, the start-up time T until the inlet pressure reaches the threshold value is long because the flow rate of the carrier gas is small.

  In the example of FIG. 5A, the set pressure p of the inlet pressure is set to 200 [kPa] as in the case of FIG. 4, but the temporary flow rate calculation unit 77 calculates the carrier gas flow rate at startup. By controlling the flow rate to be the set flow rate f, the carrier gas is supplied at a flow rate higher than the total flow rate target value during execution of the carrier gas saving function. As a result, the startup time T until the inlet pressure reaches the threshold is shorter than in the case of FIG.

  In the example of FIG. 5B, the set pressure p of the inlet pressure is set lower than in the case of FIG. 5A. On the other hand, in the example of FIG. 5C, the set pressure p of the inlet pressure is set higher than in the case of FIG. 5A. In either case of FIG. 5B and FIG. 5C, the inlet pressure reaches the threshold value by controlling the flow rate of the carrier gas to the temporarily set flow rate f calculated by the temporarily set flow rate calculation unit 77 at the time of startup. The activation time T until this time is the same as in FIG. 5A, and the activation time T is shorter than in the case of FIG.

  In the above embodiment, the configuration in which the liquid sample is vaporized in the sample introduction unit 2 (sample vaporization chamber 21) has been described. However, the present invention is not limited to this configuration, and the sample gas that has already been vaporized is used as the sample introduction unit. 2 may be supplied. In this case, the configuration may not be such that the sample vaporizing chamber 21 is formed inside the sample introduction unit 2.

  Moreover, in the above embodiment, about the structure by which the flow rate control apparatus for controlling the flow volume of the carrier gas and sample gas which are introduce | transduced into the column 1 via the column inlet 11 from the sample introduction part 2 was integrated in the gas chromatograph. Although described, it is also possible to provide the flow control device separately from the gas chromatograph.

DESCRIPTION OF SYMBOLS 1 Column 2 Sample introduction part 3 Gas supply flow path 4 Split flow path 5 Purge flow path 6 Detector 7 Control part 8 Operation part 9 Memory | storage part 10 Atmospheric pressure sensor 11 Column inlet 21 Sample vaporization chamber 31 Supply pressure sensor 32 Differential pressure sensor 33 Total flow valve 41 Split valve 51 Inlet pressure sensor 52 Purge valve 53 Purge pressure sensor 71 Total flow control unit 72 Split flow control unit 73 Purge flow control unit 74 Inlet pressure setting reception unit 75 Volume setting reception unit 76 Start time setting reception unit 77 Temporary setting flow rate calculation unit 78 Volume calculation unit

Claims (9)

A sample introduction unit;
A gas supply channel for supplying a carrier gas to the sample introduction unit;
A column into which a carrier gas and a sample gas are introduced from the sample introduction section via a column inlet;
A split flow path for discharging part of the gas in the sample introduction section;
A total flow rate detection unit for detecting the flow rate of the carrier gas in the gas supply channel;
An inlet pressure detector for detecting an inlet pressure at the column inlet;
A total flow rate controller for controlling the flow rate of the carrier gas in the gas supply flow path,
The total flow control unit controls the flow rate of the carrier gas so that the flow rate of the carrier gas detected by the total flow rate detection unit becomes a predetermined temporarily set flow rate at the time of startup, and is detected by the inlet pressure detection unit A gas chromatograph, characterized in that, after the inlet pressure reaches a threshold value, the carrier gas is controlled to a set flow rate while the inlet pressure is maintained at a predetermined set pressure.   The gas chromatograph according to claim 1, further comprising a temporarily set flow rate calculation unit that calculates the temporarily set flow rate based on the set pressure. A total flow valve provided in the gas supply flow path for adjusting the flow rate of the carrier gas in the gas supply flow path;
The temporarily set flow rate calculation unit is configured such that at least the volume of a constant region downstream from the total flow rate valve including at least the internal space of the sample introduction unit and the inlet pressure detected by the inlet pressure detection unit from the start-up are the threshold values. The gas chromatograph according to claim 2, wherein the temporarily set flow rate is calculated based on a start-up time until it reaches. A volume setting receiving unit for receiving the volume setting;
The gas chromatograph according to claim 3, wherein the temporarily set flow rate calculation unit calculates the temporarily set flow rate based on the set volume. A boot time setting receiving unit for receiving the boot time setting;
The gas chromatograph according to claim 3 or 4, wherein the temporarily set flow rate calculation unit calculates the temporarily set flow rate based on the set startup time.   The apparatus further comprises a volume calculation unit that calculates the volume based on a change in the inlet pressure detected by the inlet pressure detection unit when the flow rate of the carrier gas is controlled by the total flow rate control unit. Item 6. A gas chromatograph according to any one of Items 3 to 5. It further includes an atmospheric pressure sensor that detects atmospheric pressure,
The gas chromatograph according to any one of claims 2 to 6, wherein the temporarily set flow rate calculation unit calculates the temporarily set flow rate based on an atmospheric pressure detected by the atmospheric pressure sensor. It further includes an atmospheric pressure sensor that detects atmospheric pressure,
The gas chromatograph according to claim 6, wherein the volume calculation unit calculates the volume based on an atmospheric pressure detected by the atmospheric pressure sensor. A flow rate control device for controlling the flow rate of a carrier gas and a sample gas introduced into a column from a sample introduction unit via a column inlet,
A gas supply channel for supplying a carrier gas to the sample introduction unit;
A split flow path for discharging part of the gas in the sample introduction section;
A total flow rate detection unit for detecting the flow rate of the carrier gas in the gas supply channel;
An inlet pressure detector that detects an inlet pressure at the column inlet; and a total flow controller that controls the flow rate of the carrier gas in the gas supply channel,
The total flow control unit controls the flow rate of the carrier gas so that the flow rate of the carrier gas detected by the total flow rate detection unit becomes a predetermined temporarily set flow rate at the time of startup, and is detected by the inlet pressure detection unit After the inlet pressure reaches a threshold value, the carrier gas is controlled to a set flow rate in a state where the inlet pressure is maintained at a predetermined set pressure.

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