JP2000162187A - Hydrocarbon analyzing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrocarbon analyzing device having a simple and inexpensive structure and capable of effectively using a pretreated sample gas and preventing the sudden change of background value at the time of calibration. SOLUTION: This device comprises a hydrogen flame ionization detector 1; and a gas supplying passage 2 for alternatively supplying a sample gas S1 and an air-based calibration gas S2, a supplying passage 3 for fuel gas F, and a supplying passage 4 for supporting gas J having a zero gas purifying means 22, which are connected to the hydrogen ionization detector 1. The gas supplying passage 2 is provided with a gas switching unit 10 having a discharge part 9 for excessive gas, and the supplying passage 4 for supporting gas J is connected to the excessive gas discharge part 9 to supply the excessive gas to the hydrogen flame ionization detector 1 as the supporting gas J, and the supplying passage 4 for supporting gas J is provided with a moisture buffer means 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrocarbon analyzer for measuring the concentration of hydrocarbons contained in a sample gas such as air.

[0002]

2. Description of the Related Art For example, as one of devices for measuring the concentration of hydrocarbons (hereinafter referred to as HC) contained in the atmosphere, there is a device using a flame ionization detector (hereinafter referred to as FID). A hydrocarbon analyzer using this FID supplies a sample gas, a fuel gas, and an auxiliary gas purified to zero gas to an FID as an analysis unit, burns the sample gas inside the FID, and generates a flame at that time. The concentration of HC in the sample gas is analyzed by causing ionization with energy and measuring the current output in proportion to the amount of carbon contained in the sample gas by an appropriate method.

Meanwhile, a conventional hydrocarbon analyzer for atmospheric measurement has been configured as shown in FIG. That is, FIG.
, 1 is a FID, which has a gas supply passage 2 and supply passages 3 and 4 for fuel gas F and auxiliary combustion gas J.
Is connected.

[0004] The above gas supply flow path 2 uses the atmosphere as a sample gas S1 and the sample gas S1 and the calibration gas S2.
The filter 6, a gas flow path switching means 7 composed of, for example, a three-way solenoid valve, and a sample gas S 1 are provided downstream of the air intake (sample gas intake) 5. An electronic cooler 8 for dehumidifying and adjusting the humidity to a predetermined humidity, and a gas switching unit 10 provided with a discharge unit 9 for surplus sample gas S1 are provided in this order. 7,
An air-based combustible gas is used as a calibration gas S2, and a supply flow path 11 for the calibration gas S2 is connected.

[0005] Reference numeral 12 denotes a gas discharge flow path for discharging the surplus sample gas S1, 13 denotes a needle valve for adjusting the flow rate, 14 denotes a diaphragm type suction pump, and a downstream side of the suction pump 14 is a gas discharge portion (shown in the figure). Not connected). A drain pump 15 is connected to the electronic cooler 8, and the other end is connected to a drain discharge section (not shown).

The fuel gas supply passage 3 supplies, for example, hydrogen gas to the FID 1 as a fuel gas F.
The auxiliary gas supply passage 4 supplies air necessary for the combustion of the sample gas S1 and the fuel gas F as an auxiliary gas J. The auxiliary gas supply passage 4 includes:
A filter 17 and a humidifier 1 are provided after the air intake 16.
8, electronic cooler 19, diaphragm type suction pump 2
0, a pressure regulator 21, a zero gas purification means 22 for oxidizing and removing all the HC contained in the atmosphere, and a flow rate adjusting capillary 23 are provided in this order.

Here, the partial pressure of the oxygen concentration changes depending on the amount of water contained in the auxiliary gas J, which leads to a rapid change in the background value. And the electronic cooler 19, and after the auxiliary gas J is once humidified, the humidity is adjusted to a predetermined humidity by the electronic cooler 19, the moisture condition of the auxiliary gas J is kept constant, and the background value is reduced in the FID 1. I try to keep it stable.

[0008]

In the conventional hydrocarbon analyzer having the above-mentioned structure, foreign matter is removed from the atmosphere as the sample gas S1 by the filter 6, and the pretreatment for humidity control is performed by the electronic cooler 8. After being applied, it is supplied to the FID 1 through the gas switching unit 10.

Then, the fuel gas F is supplied to the FID 1 through the fuel gas supply passage 3. The atmosphere introduced into the auxiliary gas supply passage 4 through the air intake 16 is
After the foreign matter is removed by the filter 17 and once humidified by the humidifier 18 and pre-treated for humidity control by the electronic cooler 19, the suction pump 20 and the pressure regulator 2
1, the gas reaches the zero gas purifying means 22 and becomes a so-called zero gas in which all the HC components contained in the air after the pretreatment are oxidized.
Is supplied to FID1.

On the other hand, when calibrating the hydrocarbon analyzer, the flow path switching means 7 is switched to the supply mode of the calibration gas S2 instead of the supply of the sample gas S1, and the air-based calibration gas S2 is supplied to the FID1. The calibration is performed in about 30 minutes.

As described above, in the conventional hydrocarbon analyzer, the calibration gas S2 is supplied to the FID 1 instead of the sample gas S1 at the time of calibration, and each gas supply passage is used at the time of measuring the concentration of hydrocarbons. After 2 to 4, the sample gas S1, the fuel gas F, and the auxiliary gas J are supplied to the FID 1, and desired combustion is performed inside the FID 1. However, there are the following problems.

That is, in the conventional hydrocarbon analyzer, the gas supply passage 2 and the auxiliary gas supply passage 4 are independent of each other, and the two gas supply passages 2 and 4 have filters 6 and 17 respectively. , Electronic coolers 8, 19 and suction pump 14,
Since the device 20 is provided, the number of components of the apparatus is increased, which requires a large installation space for the apparatus, complicates the configuration, and increases the cost.

On the other hand, the above-mentioned electronic cooler 8 has a cooling capacity several times the amount of the sample gas to be supplied, and in fact, about 5 times in order to stably supply the sample gas S1 to the FID 1. However, it is extremely wasteful to discard a large amount of the sample gas S1 which has been subjected to the pretreatment of the humidity control by the electronic cooler 8 as a surplus.

The present invention has been made in consideration of the above-mentioned matters, and has as its object to reduce the number of components, to have a simple and inexpensive structure, and to effectively use a pretreated sample gas without waste. In addition to being able to
An object of the present invention is to provide a hydrocarbon analyzer capable of preventing a sudden change in a background value.

[0015]

In order to achieve the above object, the present invention connects a gas supply flow path for selectively supplying a sample gas and an air-based calibration gas to a flame ionization detector. In addition, the hydrocarbon flame analyzer further comprising, in the flame ionization detector, a fuel gas supply flow path, and a combustion gas supply flow path provided with a hydrocarbon-free zero gas purifying means. A gas switching unit that discharges excess gas is provided in the gas supply channel, and a surplus gas discharge unit of the gas switching unit is connected to a supply channel of an auxiliary gas including the zero gas purification unit,
It is characterized in that the excess gas purified to zero gas is supplied to the hydrogen flame ionization detector as an auxiliary gas, while a moisture buffer means is provided in the supply channel of the auxiliary gas.

In the above-structured hydrocarbon analyzer,
Since it is used as a combustion support gas without discarding a large amount of surplus gas that has been pretreated for humidity control, unlike conventional hydrocarbon analyzers, filters, electronic coolers and suction pumps are duplicated. There is no need to provide it, and at this time, as an electronic cooler for the sample gas, the cooling capacity of the sample gas is originally large, so that the cooling capacity is not increased, or the excess gas is not required without a significant increase. Since it can be used as a combustion supporting gas, the configuration of the apparatus can be simplified, and the entire apparatus can be configured at low cost.

Here, when a surplus calibration gas is simply used as a combustion assisting gas at the time of calibration of the hydrocarbon analyzer, the calibration gas is a dry gas, which may cause inconvenience in calibration.

That is, referring to FIG. 1, if the sample gas S1 for combustion used for measuring the concentration of hydrocarbons is completely dried by the electronic cooler 8, the following inconvenience does not occur. However, in order to completely dry-process the sample gas S1, not only a large-sized electronic cooler 8 having a high cooling capacity is required but also the response is delayed, so that the electronic cooler 8 is generally cost-effective. As described above in consideration of the above, a sample having a cooling capacity of about 5 times the sample gas amount to be stably supplied to the FID 1 is installed, and the humidity of the sample gas S1 is adjusted as dry as possible. .

The surplus sample gas for assisting combustion used when measuring the concentration of hydrocarbons is a humidity control gas, whereas the gas used for calibration is an air-based dry gas. Since the moisture condition differs between the time and the calibration, and the partial pressure of the oxygen concentration of the auxiliary combustion gas supplied to the FID changes abruptly, there is a concern that the background value may change abruptly.

Therefore, in the present invention, a moisture buffer means is provided in the supply channel of the auxiliary gas, and when the concentration of hydrocarbons is measured, that is, except for the calibration performed in a short time, the moisture buffer means is supplied from the humidified sample gas. So that the moisture is always held in the moisture buffer means, and at the time of calibration, the moisture is added to the dry calibration gas by the moisture buffer means. A sudden change in the amount of water is suppressed, and this makes the water condition of the auxiliary combustion gas almost constant, thereby preventing a sudden change in the background value. Calibration has become stable.

For example, 1 ppm for 5 ppm of CH ₄
In the case of the output of 200 mV, as shown in Table 1, the conventional hydrocarbon analyzer having no water buffer means, when a wet gas (saturated at 5 ° C.) and a dry gas are alternately flown as auxiliary combustion gases, While the ground value fluctuated by 20 mV, the background value did not fluctuate at all under the same conditions in the hydrocarbon analyzer according to the present invention provided with the moisture buffer means.

[0022]

[Table 1]

The present invention is particularly useful in a hydrocarbon analyzer for atmospheric measurement.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows one embodiment of a hydrocarbon analyzer according to the present invention. Among the reference numerals assigned to this figure, the same reference numerals as those in FIG. 2 are the same, and the description thereof will be omitted.

The major difference between the hydrocarbon analyzer of this embodiment and that shown in FIG. 2 is that the hydrocarbon analyzer is provided on the downstream side of the gas discharge passage 12 connected to the surplus gas discharge section 9 of the gas switching unit 10. The supply channel 4 of the auxiliary gas J provided with the zero gas purifying means 22 containing no hydrogen is connected, and the surplus gas passing through the zero gas purifying means 22 is used as the auxiliary gas J as a FID (hydrogen flame ionization detector) 1. The filter 17, the humidifier 18, the electronic cooler 19, and the suction pump 20 in the conventional hydrocarbon analyzer shown in FIG. 2 are omitted. Hereinafter, the hydrocarbon analyzer according to the present invention will be described in detail with reference to FIG.

That is, in FIG.
In addition, a needle valve 13 for adjusting a flow rate, a diaphragm-type suction pump 14, a buffer tank 24, a pressure regulator 21, a zero gas purification unit 22, and a moisture buffer unit 2
5 and the capillary 23 are connected in this order, so that the surplus gas purified to zero gas is supplied to the FID 1.

The buffer tank 24 prevents the pulsation of the gas flow caused by the suction operation of the suction pump 14 from being transmitted to the auxiliary combustion gas supply flow path 4, and 26 is connected to the buffer tank 24. Check valve.

The water buffer means 25 is provided with a moisture absorbent such as activated alumina, silica gel or zeolite.
A line which is filled so as to have air permeability in a case constituting a flow path and in which the gas flow rate and the pressure condition are almost constant, that is, disposed between the pressure regulator 21 and the zero gas purification means 22 However, the placement site is not specified.

The operation of the above-structured hydrocarbon analyzer will be described. First, regarding the concentration measurement of hydrocarbons, the atmosphere as the sample gas S1 introduced into the sample gas inlet 5 is
Foreign matter is removed by the filter 6, reaches the electronic cooler 8 via the gas flow switching means 7, and is subjected to a humidity control process for making it as dry as possible.

The humidified sample gas S1 reaches the gas switching unit 10 and a part of the sample gas S1 is supplied to the FID 1. On the other hand, the excess sample gas S1 is drawn by the suction pump 14 and discharged to the gas discharge passage 12. Is done.

Then, the sample gas S1 discharged into the gas discharge channel 12 reaches the water buffer means 25 from the buffer tank 24 via the pressure regulator 21, and the water contained in the sample gas S1 becomes saturated until the water contained therein becomes saturated. Suctioned by the buffer means 25, and then to the zero gas purification means 22,
Here, the HC component is oxidized and purified to a zero gas containing no HC component, and this zero gas is passed through the capillary 23 to the F gas.
It is introduced into ID1 as auxiliary combustion gas J.

At this time, the auxiliary combustion gas J is supplied to the check valve 2
6. The flow rate is adjusted by the pressure regulator 21 and the capillary 23, and is introduced into the FID 1 at a predetermined flow rate.

Since the fuel gas F is introduced into the FID 1 in addition to the sample gas S1 and the auxiliary gas J, the sample gas S1 is generated in the FID 1 in the presence of the fuel gas F and the auxiliary gas J. Predetermined combustion is performed.

As described above, in the hydrocarbon analyzer according to the present invention, the surplus humidified sample gas S1 discharged from the gas switching unit 10 is not wastefully discarded and the auxiliary gas supply passage 4 And a zero gas treatment is performed by a zero gas purifying means 22 provided in the supply flow path 4.
Since it is supplied to ID1, unlike the conventional hydrocarbon analyzer, the filter 17, the humidifier 18, the electronic cooler 1
9. There is no need to provide a suction pump 20 or the like,
In addition to the simplification of the auxiliary combustion gas supply passage 4, the number of parts of the entire apparatus is reduced, so that the apparatus can be configured at low cost.

On the other hand, when the hydrocarbon analyzer is calibrated, the flow path switching means 7 is switched to the supply mode of the calibration gas S2 instead of the supply of the sample gas S1, and the dry calibration gas S2 of the air base is changed to the supply mode. The gas reaches the gas switching unit 10 through the electronic cooler 8, a part of the dry calibration gas S 2 is supplied to the FID 1, and the surplus gas S 2 is discharged to the gas discharge passage 12 as the auxiliary combustion gas J.

The dry gas for auxiliary combustion discharged into the gas discharge passage 12 is supplied from the buffer tank 24 to the pressure regulator 2.
1 to the moisture buffer means 25, where the moisture held by the moisture buffer means 25 is sucked into the auxiliary gas J, whereby the auxiliary gas J is wetted and then passed through the zero gas purification means 22. Is purified into a zero gas, and this zero gas is introduced into the FID 1 as the auxiliary combustion gas J.

Since the auxiliary combustion gas J contains moisture, the rapid change in the amount of water of the auxiliary combustion gas J introduced into the FID 1 can be suppressed. Since the calibration gas S2 burns under almost the same moisture conditions as when measuring the hydrocarbon concentration, the calibration of the hydrocarbon analyzer is stably performed in a state in which the background value is not rapidly changed. Will be.

Here, if the HC in the sample gas S1 changes suddenly, the load on the zero gas purifying means 22 is increased. However, the activated alumina or the like provided in the water buffer means 25 has an ability to adsorb HC. Therefore, the moisture buffer means 25 has a function of placing the sample gas S1 and the auxiliary combustion gas J under substantially the same moisture conditions, and also has a function of buffering the load on the zero gas purification means 22. .

It should be noted that the above-mentioned hydrocarbon analyzer uses H
Needless to say, it can be used for other than the measurement of the C concentration, but particularly, the configuration shown in FIG. 1 has an excellent effect in a measurement method in which the atmosphere is sucked and used as the sample gas S1.

[0040]

As described above, according to the present invention,
A hydrocarbon analyzer that is simple and inexpensive with few components, can use the excess humidity control gas effectively as a combustion support gas, and prevents sudden changes in background value during calibration. Is provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an example of the configuration of a hydrocarbon analyzer.

FIG. 2 is a configuration diagram schematically showing a configuration of a conventional hydrocarbon analyzer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hydrogen flame ionization detector (FID), 2 ... gas supply channel, 3 ... fuel gas supply channel, 4 ... auxiliary gas supply channel, 9
... Excess gas discharge unit, 10 ... Gas switching unit, 21
... Zero gas purification means, 26 ... Moisture buffer means, F ... Fuel gas, J ... Combustion gas, S1 ... Sample gas, S2 ... Calibration gas.

Claims (2)

[Claims] A gas supply flow path for selectively supplying a sample gas and an air-based calibration gas is connected to a flame ionization detector, and further, a fuel gas flow is supplied to the flame ionization detector. A gas switching unit for discharging a surplus gas to the gas supply channel in a hydrocarbon analyzer configured by connecting a supply channel and a supply channel of a combustion assisting gas provided with a purifying means for zero gas containing no hydrocarbon. Is provided, and a surplus gas discharge section of the gas switching unit is connected to a supply flow path of an auxiliary gas provided with the zero gas purification means,
A hydrocarbon analyzer characterized in that excess gas purified into zero gas is supplied to a hydrogen flame ionization detector as auxiliary gas, and a moisture buffer means is provided in a supply channel of the auxiliary gas. 2. The hydrocarbon analyzer according to claim 1, wherein the sample gas is air.