JP4790436B2 - Hydrogen flame ionization analyzer - Google Patents

Description

  The present invention relates to a flame ionization analyzer, and more particularly to a flame ionization analyzer suitable for measuring a volatile organic compound concentration.

As a measuring method of the volatile organic compound concentration, there are a method using a catalytic oxidation-non-dispersion type infrared analyzer (hereinafter referred to as “NDIR meter”) and a hydrogen flame ionization analyzer (hereinafter referred to as “FID meter”). ) Is known.
The flame ionization detector (hereinafter referred to as “FID detector”) of the FID meter detects the total amount of volatile organic compounds at one time, but is a gas chromatograph with a separation column arranged upstream of the FID detector. A graph apparatus is also known (Patent Document 1).
JP 2003-302376 A

Volatile organic compound concentrations stipulated in Article 15-2 and Article 15-3 No. 1 of the Air Pollution Control Law Enforcement Regulations that came into effect on April 1, 2006 are the Ministry of the Environment Notification No. 61 (hereinafter simply “Notification”). ")").
According to this notice, the volatile organic compound concentration is the concentration obtained by subtracting the concentration of the specified exempted substance from the organic compound concentration measured by the NDIR meter or FID meter, but the value does not exceed the regulation value. Is an organic compound concentration as measured with an NDIR meter or FID meter. Regarding excluded substances, gas chromatography using a FID detector (GC-FID), gas chromatography using an electron capture detector (GC-ECD), and gas chromatography using a mass spectrometer (GC-MS). It is determined to be measured by either.

In addition, according to the measurement method based on the notification, the sample gas to be measured must be collected in a collection bag. And it is prescribed | regulated that the flow rate adjustment valve which can control the flow volume of 0.5-5 L / min is prescribed | regulated to the sampling method based on notification, and the sampling time is 20 minutes or 1 process. .
Therefore, the amount of sample gas collected cannot exceed 100L. Usually, 20 L of sample gas is collected at a flow rate of 1 L / min, and 20 L of sample gas is collected in one collection bag.

When the measured value by the FID meter exceeds a certain value, it is necessary to measure the excluded substance with the same sample gas, so the sample gas in the collection bag is not used up for the measurement with the FID meter. It is desirable to leave as much as possible.
However, the amount of sample gas in the collection bag is limited as described above. On the other hand, the time until the measured value of the sample gas by the FID meter is stabilized is not always constant. For example, it is known that it takes time when a sample gas contains a large amount of easily adsorbed substances.
Therefore, if it is attempted to leave the sample gas necessary for the measurement of the excluded substance and stop the supply of the sample gas after a certain time has elapsed, the measurement is performed before the measurement value of the FID meter is stabilized. You may be censored. That is, there is a possibility that a correct measurement value of the sample gas cannot be obtained. In this case, a situation in which the measurement must be performed again from the FID meter is expected.

  The present invention has been made in view of the above circumstances, and while being able to reliably obtain the measurement value of the FID meter, leaving as much sample gas as possible in the collection bag, without performing another sampling, It is an object of the present invention to provide an FID meter that is highly likely to measure excluded substances.

In order to achieve the above object, the present invention employs the following configuration.
[1] A flame ionization detector, a sample gas supply path for supplying a sample gas to the flame ionization detector , a supply valve provided in the sample gas supply path, and a heater for heating the flame ionization detector , and a stability determination computing unit output value of the hydrogen flame ionization detector to determine whether it has stabilized, the output value of the hydrogen flame ionization detector after turning on the heater, the stability determination computing unit has stabilized Supply of sample gas or calibration gas to the flame ionization detector was started , and the stability determination calculator stabilized the output value of the flame ionization detector when the sample gas was being supplied. A hydrogen gas ionization analyzer characterized in that when it is determined, the sample gas supply path is shut off by the supply valve to stop the supply of the sample gas to the hydrogen flame ionization detector.

[2] is et al, includes a zero gas supply path for supplying the zero gas to the hydrogen flame ionization detector, the output value of the hydrogen flame ionization detector when the zero gas is supplied, determines the stability determination calculator is stable Then, the supply of the sample gas or the calibration gas to the flame ionization detector is started, and the flame ionization analyzer according to [1 ] .
[3] The flame ionization analyzer according to [1] or [2] , wherein the measurement target is a volatile organic compound concentration.

According to the invention of [1], since the supply of the sample gas is shut off after confirming that the output value of the flame ionization detector is stable, the measured value of the FID meter can be obtained with certainty. Moreover, since supply of the sample gas is shut off when it is confirmed that the output value of the flame ionization detector is stable, it is possible to leave as much sample gas as possible in the collection bag. Therefore, there is a high possibility that the excluded substances can be measured by GC-FID or the like without performing sampling again.
In addition, since supply of sample gas or calibration gas is started after confirming that the output value of the flame ionization detector has been stabilized by warm-up operation, the output value when sample gas or calibration gas is supplied becomes early. It is stable and the amount of these gases used can be minimized. Further, when it is confirmed that the output value of the hydrogen flame ionization detector is stable, the warm-up operation is terminated and the supply of the sample gas or the like is started, so that the warm-up operation can be completed in a necessary and sufficient time. .
According to the invention of [ 2 ], since the supply of the sample gas or the calibration gas is started after the gas in the FID meter is sufficiently purged with the zero gas, the output value when the sample gas or the calibration gas is supplied becomes early. It is stable and the amount of these gases used can be minimized. Further, when it is confirmed that the output value of the flame ionization detector is stable, the purge is finished and the supply of the sample gas or the like is started, so that the purge can be finished in a necessary and sufficient time.
According to the invention of [ 3 ], the volatile organic compound concentration can be measured appropriately and efficiently in accordance with the notification of the Ministry of the Environment.

An FID meter according to an embodiment of the present invention will be described with reference to FIG.
Each valve shown in FIG. 1 is a solenoid valve, and the ports indicated by white triangles in the figure are normally open ports that are opened only when they are off, and the ports indicated by black triangles in the figure are on. A normally closed port that is open only when the port is indicated by a white and black triangle in the figure is a common port that is open regardless of whether it is on or off.

  The FID meter of the present embodiment includes a sample gas supply path 10 from the sample gas inlet 10a to the outlet 10b. In the sample gas supply path 10, a pump P1, a three-way valve SV1, a three-way valve SV2 (supply valve), a capillary CP1, and an FID detector 1 are sequentially provided from the sample gas inlet 10a side.

The three-way valve SV1 is provided in the sample gas supply path 10 by using a common port and a normally open port, and the three-way valve SV2 is provided by using a common port and a normally closed port.
A calibration gas introduction path 20 whose upstream end is a calibration gas inlet 20a is connected to the normally closed port of the three-way valve SV1. The calibration gas supply path 20 and the sample gas supply path 10 on the downstream side from the point where the calibration gas introduction path 20 merges are calibration gas supply paths.
A zero gas introduction path 31 is connected to the normally open port of the three-way valve SV2. The zero gas introduction path 31 is connected to the downstream side of the air introduction path 30 whose upstream end is the air introduction port 30a. The zero gas introduction path 31 and the sample gas supply path 10 downstream from the point where the zero gas introduction path 31 merges are the zero gas supply path of the present invention.
Further, an auxiliary combustion gas introduction path 32 is connected to the FID detector 1, and a capillary CP 2 is provided in the auxiliary combustion gas introduction path 32. This auxiliary combustion gas introduction path 32 is also connected to the downstream side of the air introduction path 30.

  The air introduction path 30 is provided with a pump P2 and a combustion furnace 33 for removing organic substances in the air. Further, the hydrogen gas introduction path 40 whose upstream end is the hydrogen gas inlet 40 a is connected to the downstream side of the three-way valve SV 2 of the sample gas supply path 10 and to the upstream side of the FID detector 1. The hydrogen gas introduction path 40 is provided with a two-way valve SV3 and a capillary CP3 which are normally closed valves.

The FID detector 1 is housed in an oven (not shown) whose interior is heated by a heater, and is heated to a predetermined temperature (usually 60 ° C. ± 1 ° C.). The capillaries CP1 to CP3 are also housed in the same oven and heated to a certain temperature.
The FID meter detects the electric current that flows when carbon of the organic compound in the sample gas is ionized by supplying the FID detector 1 with sample gas, hydrogen gas, and auxiliary combustion gas at a constant rate and burning them. Therefore, in order to obtain a stable measurement value, it is necessary to always supply a constant amount and a constant ratio of sample gas, hydrogen gas, and auxiliary combustion gas to the FID detector 1. On the other hand, the gas flow rate varies greatly under the influence of temperature. Therefore, the capillaries CP1 to CP3 and the FID detector 1 for determining the flow rate must be kept at a constant temperature.

  The ignition of the FID detector 1, the oven heater, the three-way valve SV1, the three-way valve SV2, the two-way valve SV3, and the pumps P1, P2 are controlled by the sequence drive circuit C1. The signal of the FID detector 1 is supplied to the stability determination calculator C2, and the stability determination calculator C2 can determine whether it is stable. The discrimination result of the stability discrimination calculator C2 is given to the sequence drive circuit C1.

The FID meter of the present embodiment includes a warm-up step for performing a warm-up operation, a calibration step using a calibration gas, a measurement step for measuring a sample gas, a purge step performed before and after the measurement step, an end step after the completion of the sample gas measurement, and the like. A series of operations are automatically performed. The FID meter according to the present embodiment determines the end point of each step based on the result of stability determination by the stability determination computing unit C2.
Hereinafter, after describing the stability determination, each step will be described in detail.

[Stable determination]
For example, the determination of whether or not it is stable (stability determination) is performed as follows. First, the output value _{D 0} at time _{T 0,} the difference ΔD between the output value _{D x} at time _{T x} has elapsed determination time _{T a} from the time _{T 0} is, if within a predetermined permissible range _{D a} stable If it does not fit, it is determined that it is not stable.
The stability determination can also be performed as follows. First, n output values D _{1 to} D _n are acquired from time T ₁ to time T _y when the determination time T _b has elapsed, and the maximum output value D _max and the minimum output value D _min between them are acquired. the difference [Delta] D 'is determined stable if within a predetermined permissible range D _b, is determined not to be stable if not fall.
Note that the output value used for the stability determination calculation may be the current value itself, which is the output value from the FID detector 1, or a value obtained by converting this into a voltage value, organic compound concentration, or the like.
When it is determined that the output value is not stable, the stability determination computing unit C2 repeats the above stability determination. When it is determined that the output value is stable, the stability determination calculation unit C2 ends the stability determination and sends a stability signal to the sequence driving circuit C1.

[Warming step]
First, the sample gas inlet 10a is connected to a collection bag for collecting the sample gas or an autosampler in which the collection bag is arranged, and the power button is pressed.
When the power button is pressed, warm-up operation is started. That is, the heater is turned on by the sequence driving circuit C1, and heating in the oven is started. The temperature in the oven is controlled to be kept at a set temperature (60 ° C. ± 1 ° C.). Further, the two-way valve SV3 and the pump P2 are turned on while the three-way valve SV1 and the three-way valve SV2 and the pump P1 are turned off. Then, the FID detector 1 is ignited.
Thus, zero gas flows into the FID detector 1 and hydrogen gas and auxiliary combustion gas are supplied, and an output value corresponding to zero organic compound concentration is obtained. The stability determination calculator C2 sequentially acquires output values from the FID detector 1 and determines whether or not the output values are stable.
When the stability determination computing unit C2 determines that the output value is stable and sends a stability signal to the sequence drive circuit C1, the sequence drive circuit C1 that has received the stability signal shifts to the calibration step.
Since the heater ON state, the FID detector 1 ignition state, and the two-way valve SV3 and the pump P2 ON state are continued unless the process proceeds to the end step, these steps in the calibration step, the measurement step, and the purge step are continued. A description of the state is omitted.

[Calibration step]
In the calibration step, the three-way valve SV1 and the three-way valve SV2 are turned on by the sequence drive circuit C1.
As a result, the calibration gas flows into the FID detector 1 and the hydrogen gas and the auxiliary combustion gas are supplied, and an output value corresponding to the concentration of the organic compound in the calibration gas is obtained. The stability determination calculator C2 sequentially acquires output values from the FID detector 1 and determines whether or not the output values are stable.
When the stability determination computing unit C2 determines that the output value is stable and ends the stability determination, calibration calculation processing is performed based on the output value at the end of the stability determination. Here, the calibration calculation processing is a current value that is an output value from the FID detector 1 or a value obtained by converting this into a voltage value and an organic compound so that the output from the FID detector 1 can be converted into an organic compound concentration. A process for obtaining and storing the relationship with the density.
Further, when the stability determination computing unit C2 determines that the output value is stable and sends a stability signal to the sequence drive circuit C1, the sequence drive circuit C1 that has received the stability signal shifts to the purge step and performs calibration. The gas supply path is blocked by the three-way valve SV2 in the sample gas supply path 10 downstream from the point where the calibration gas introduction path 20 joins, and the flow of the calibration gas to the FID detector 1 is stopped.
Although not shown, the calibration step can also be started by pressing a calibration start button.

[Purge step]
In the purge step, the three-way valve SV1 and the three-way valve SV2 are turned off by the sequence drive circuit C1. The off state of the pump P1 continues as it is.
As a result, the calibration gas in the sample gas supply path 10 downstream from the point where the zero gas introduction path 31 joins is purged with the zero gas (in the purge step after the measurement step described later). As the purge proceeds, the output from the FID detector 1 gradually decreases, and when the purge is sufficiently performed, an output value corresponding to zero organic compound concentration can be obtained. The stability determination calculator C2 sequentially acquires output values from the FID detector 1 and determines whether or not the output values are stable.
When the stability determination computing unit C2 determines that the output value is stable and sends a stability signal to the sequence drive circuit C1, the sequence drive circuit C1 that has received the stability signal shifts to the next measurement step.
Although not shown, the purge step can also be started by pressing a purge start button.

[Measurement step]
In the measurement step, the three-way valve SV1 is turned off and the three-way valve SV2 and the pump P1 are turned on by the sequence drive circuit C1.
Thereby, the sample gas flows into the FID detector 1 and the hydrogen gas and the auxiliary combustion gas are supplied, and an output value corresponding to the concentration of the organic compound in the sample gas is obtained. The stability determination calculator C2 sequentially acquires output values from the FID detector 1 and determines whether or not the output values are stable.
When the stability determination computing unit C2 determines that the output value is stable and ends the stability determination, the organic compound concentration is obtained based on the output value at the end of the stability determination.
When the stability determination calculator C2 determines that the output value is stable and sends a stability signal to the sequence drive circuit C1, the sequence drive circuit C1 that has received the stability signal makes a transition to the purge step or the end step. The sample gas supply path 10 is shut off by the three-way valve SV2, and the flow of the sample gas into the FID detector 1 is stopped.
Here, after the measurement step, when the measurement step is further performed, the process proceeds to the purge step. When the operation of the FID meter is completely finished, the process proceeds to an end step.
Although not shown, the measurement step can also be started by pressing a measurement start button.

  When the measurement step is further performed after the measurement step is completed, the sample gas is switched during the purge step performed in the meantime. When an autosampler is connected to the sample gas inlet 10a, the autosampler switches the collection bag each time during the purge step. In this case, when the measurement step for the final collection bag is completed, the sequence drive circuit C1 shifts to the end step. The end of the measurement step for the final collection bag means that the number of collection bags is stored in advance in the stability determination computing unit C2 or is input from the operation unit of the FID meter, or a new collection bag. This can be determined by, for example, receiving a measurement end signal from the autosampler that has detected the absence of the stability determination operation unit C2.

When a collection bag is directly connected to the sample gas inlet 10a, the operator can manually replace the connected collection bag and repeat the measurement in the same manner. In this case, the collection bag must be exchanged by the time the next measurement step starts, so a message prompting the exchange of the bag is displayed, voice (including buzzer, etc.), communication (mobile) It is desirable to notify the operator by telephone or mobile mail, etc., and not enter the measurement step as the state of the idling step described later until the input that the collection bag has been exchanged is entered. .
If there is no particular designation, it may be assumed that all measurements have been completed when one measurement is completed, and the process proceeds to an end step.

[End step]
In the end step, the sequence drive circuit C1 turns off the three-way valve SV1, the three-way valve SV2, and the pump P1 as in the purge step. Then, the heater of the oven is turned off while the two-way valve SV3 and the pump P2 are kept on.
Thereby, the measurement gas in the sample gas supply path 10 downstream from the point where the zero gas introduction path 31 joins is purged with the zero gas. In addition, the temperature in the oven gradually decreases. As purge and temperature decrease proceed, the output from the FID detector 1 gradually decreases, and when purge and temperature decrease proceed sufficiently, the output value generally approaches zero. The stability determination calculator C2 sequentially acquires output values from the FID detector 1 and determines whether or not the output values are stable.
When the stability determination computing unit C2 determines that the output value is stable and sends a stability signal to the sequence drive circuit C1, the sequence drive circuit C1 that receives the stability signal turns off the power supply of the entire apparatus. Alternatively, the power is turned off after a preset time has elapsed.
Thereby, the two-way valve SV3 and the pump P2 are also turned off, and the FID detector 1 is extinguished by shutting off all the supply of zero gas, hydrogen gas, and auxiliary combustion gas.
The end step can also be started by pressing an end button (not shown).

[Idling step]
Moreover, in this embodiment, it can transfer to an idling step instead of an end step. Although not shown, it can be selected in advance with an operation key whether to move to the end step or the idling step when all the measurements are completed.
In the idling step, the sequence driving circuit C1 turns off the three-way valve SV1, the three-way valve SV2, and the pump P1 as in the purge step. Then, the ON state of the two-way valve SV3 and the pump P2 and the ON state of the oven heater are continued.
Thereby, the inside of the sample gas supply path 10 downstream from the point where the zero gas introduction path 31 joins is purged with the zero gas. Thereafter, the state in which the zero gas, the hydrogen gas, and the auxiliary combustion gas are supplied to the FID detector 1 in the ignition state continues while the temperature in the oven is maintained at the predetermined temperature.
By shifting to the idling step instead of the end step, it becomes possible to immediately shift to the measurement step or the calibration step.

When the collection bag is directly connected to the sample gas inlet 10a and the operator manually replaces the connected collection bag, it is preferable to shift to the idling step when the purge step is completed. And if it is made not to transfer to a measurement step until a measurement start button is pushed, the situation which transfers to a measurement step in the state where exchange of a collection bag is not in time can be avoided.
In addition, even when an autosampler is connected to the sample gas inlet 10a, a collection bag other than the collection bag set in the autosampler can be used if a collection bag is newly set in the autosampler and measurement is to be continued. When it is desired to perform measurement by directly connecting to the sample gas inlet 10a, it is preferable to shift to the idling step when the purge step is completed. Then, as soon as necessary preparations such as resetting the collection bag are made, the measurement can be resumed by immediately proceeding to the measurement step by pressing the measurement start button.
The idling step can also be started by pressing an idling start button (not shown).

According to this embodiment, since the sample gas and the calibration gas are supplied to the FID detector 1 until it is determined that the output value is stable, the measurement and the calibration can be reliably performed. Further, since the supply of the sample gas and the calibration gas to the FID detector is stopped immediately after the stability determination is finished, these gases are not used more than necessary.
In particular, it is possible to leave as much sample gas as possible in the collection bag that can be collected only in a limited amount (up to 20 L) in the collection bag. Therefore, when the organic compound concentration by the FID meter exceeds the regulation value, there is a high possibility that the excluded substances can be measured by GC-FID or the like using the remaining sample gas.

  In this embodiment, the three-way valve SV2 is used as the supply valve. However, the supply valve is particularly limited as long as it can shut off the sample gas supply path so as to stop the supply of the sample gas to the flame ionization detector. For example, a two-way valve or a six-way valve may be used. When a two-way valve is used as a supply valve instead of the three-way valve SV2, the zero gas introduction path 31 is joined to the sample gas supply path on the downstream side of the supply valve, and a two-way valve is also provided in the zero gas introduction path 31. It is preferable that only one of the sample gas and zero gas is supplied to the FID detector.

In the present embodiment, the zero gas introduction path 31 and the auxiliary combustion gas introduction path 32 are both connected to the downstream side of the air introduction path 30, but only the auxiliary combustion gas introduction path 32 is provided on the downstream side of the air introduction path 30. The zero gas introduction path 31 may be connected to supply zero gas from a zero gas cylinder.
Of course, a filter, a dehumidifier, and the like may be additionally provided in the air introduction path 30 as appropriate.

  In the present embodiment, the FID detector 1 and the capillaries CP1 to CP3 are calibrated so as to be accommodated in the oven. However, the portion where the temperature change may affect the output of the FID detector 1 is as much as possible. It is preferable to accommodate in.

  Further, in this embodiment, a warm-up step for determining stability by flowing zero gas into the FID detector 1 after pressing the power button is provided, but immediately after pressing the power button, the process proceeds to the calibration step. Also good. Similarly to the above, when the stability determination computing unit C2 determines that the output value is stable and ends the stability determination, calibration calculation processing is performed based on the output value at the end of the stability determination. In this case, the warm-up is performed while the calibration gas is allowed to flow into the FID detector 1, and the calibration calculation process can be performed and the completion of the warm-up can be confirmed by the stability of the output of the FID detector 1.

It is a schematic block diagram of the FID meter which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... FID detector, 10 ... Sample gas supply path, 20 ... Calibration gas introduction path,
30 ... Air introduction path, 31 ... Zero gas introduction path, 32 ... Auxiliary combustion gas introduction path, 33 ... Combustion furnace,
40 ... Hydrogen gas introduction path,
SV1 ... three-way valve, SV2 ... three-way valve, SV3 ... two-way valve, P1 ... pump, P2 ... pump,
CP1 ... capillary, CP2 ... capillary, CP3 ... capillary C1 ... sequence drive circuit, C2 ... stability discrimination calculator

Claims (3)

A hydrogen flame ionization detector; a sample gas supply passage for supplying a sample gas to the hydrogen flame ionization detector ; a supply valve provided in the sample gas supply passage; a heater for heating the hydrogen flame ionization detector; A stability determination computing unit that determines whether or not the output value of the ionization detector is stable,
For the output value of the flame ionization detector after turning on the heater, when the stability determination computing unit determines that it is stable, start supplying the sample gas or calibration gas to the flame ionization detector,
When the stability determination computing unit determines that the output value of the flame ionization detector when the sample gas is being supplied is stable, the supply valve shuts off the sample gas supply path and supplies the flame ionization detector to the flame ionization detector. A flame ionization analyzer characterized by stopping the supply of sample gas. Furthermore, a zero gas supply path for supplying zero gas to the flame ionization detector is provided, and when the stability determination computing unit determines that the output value of the flame ionization detector when the zero gas is supplied is stable, 2. The hydrogen flame ionization analyzer according to claim 1, wherein the supply of the sample gas or the calibration gas to the flame ionization detector is started. The hydrogen flame ionization analyzer according to claim 1 or 2 , wherein the measurement target is a volatile organic compound concentration.

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