JPH0961352A - Gas introducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas introducing device in which the moisture concentrations of a reference gas and a sample gas are equilibrated, and the responsiveness of a soluble gas (SO2 , NO2 or the like) can be significantly improved without generation of condensed water or drain. SOLUTION: This gas introducing device is formed out of a tubular moisture permeable film 3 for introducing a sample gas from a sample gas outflow line 7 to an analyzer 10, an outside case 2 covering the moisture permeable film 3 so as to form a fixed space with it and having a reference gas inlet port and a reference gas outflow port, a reference gas circulating line 9 having a reference gas introducing valve 6, a reference gas outflow valve 9, a circulating pump 11 and a flowmeter 12 arranged therein, and connected to the outside case 2, and a reference gas outflow line 15 connected to the reference gas outflow port to introduce the reference gas to the analyzer 10. A sample gas circulating line may be provided in both end parts of the moisture permeable film 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas analyzer according to a comparison method used in, for example, an infrared gas analyzer, a cross-modulation type gas analyzer, etc. The present invention relates to a gas introduction device capable of approximating the concentrations and reducing the influence of moisture interference and increasing the response speed.

[0002]

2. Description of the Related Art In the case of analyzing combustion exhaust gas such as flue gas, an infrared gas analyzer such as a comparison method or a cross modulation method is used. In such a gas analyzer, a two-series electronic cooler is often used as a means for reducing the interference effect due to moisture and for balancing the moisture concentration. That is, as shown in FIG.
Then, the two lines of the sample gas flow path 23 are passed through the two-line electronic cooler 20, and the comparison gas and the sample gas are introduced toward the analyzer through the distributor (switching valve) 22. In the electronic cooler 20, the water in the reference gas and the water in the sample gas are both condensed and dropped in the trap 24. In this case, the water concentration of both the comparison gas and the sample gas is determined by the dehumidifying dew point temperature of the electronic cooler 20.

[0003]

Conventionally, when the inlet dew point temperature of each line of the comparative gas flow path 21 or the sample gas flow path 23 is equal to or lower than the set temperature of the dehumidifying dew point of the two-series electronic cooler 20, It was necessary to humidify in the previous stage. Further, condensed water is generated in the cooling section of the two-series electronic cooler 20, and particularly when measuring a water-soluble gas such as sulfurous acid gas (SO ₂ ), a large response delay occurs due to gas dissolution, and span gas calibration is performed. There were drawbacks such as long time or low indication value. Further, since the electronic cooler generally has a dew point temperature of about 5 ° C, there is a limit in removing water in the sample gas. That is, if the dehumidifying dew point temperature is below 0 ° C., it becomes difficult for gas to flow when the moisture freezes, so the dehumidifying dew point temperature is at least about 5 ° C. There was a limit to dehumidification with an electronic cooler.

The present invention has been made by paying attention to the above-mentioned problems, and even at temperatures below the freezing point, the water concentrations of the gas on the comparison side and the gas on the sample side are balanced so that condensed water and drainage are not generated and solubility is improved. An object of the present invention is to provide a gas introduction device capable of greatly improving the response of gas (SO ₂ , NO _2, etc.).

[0005]

That is, in order to solve the above problems, the present invention provides a gas introducing device in which a constant space is formed between a moisture permeable membrane portion and the moisture permeable membrane portion. As described above, in the moisture permeable membrane portion of the membrane type dehumidifier composed of an outer case which covers the moisture permeable membrane portion and is provided with a purge gas inlet and a purge gas outlet, a sample gas introduction pipe line and A sample gas outflow line for introducing the sample gas into the analyzer is connected, and a comparative gas introduction valve and a comparative gas outflow valve are provided on the way to the page gas inlet and the page gas outlet of the outer case. And a circulation gas passage for arranging circulation means, and a comparison gas outlet pipe for introducing the comparison gas into the analyzer is connected to the comparison gas outlet.

Alternatively, the gas introducing device covers the moisture permeable membrane so that a certain space is formed between the moisture permeable membrane and the moisture permeable membrane, and the purge gas introducing port and the purge gas are provided. An outer case provided with an outflow port, and a sample gas introduction pipe line and a sample gas outflow pipe line for introducing a sample gas into an analyzer are connected to the moisture permeable membrane portion of the membrane type dehumidifier, The sample gas inflow conduit connected to both ends of the moisture permeable membrane and the three-way valve arranged in the sample gas outflow conduit are connected to both ends of the sample gas circulation conduit in which a circulation means is arranged, and the outer case of the outer case is connected. A comparative gas inlet and a comparative gas outlet are connected to a comparative gas inlet valve, a comparative gas outflow valve, and a purge gas circulation pipe line in which a circulation means is arranged, and further to the comparative gas outlet. The comparative gas outflow line that introduces the comparative gas into the analyzer Characterized by comprising connection to.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a first embodiment of a gas introduction device of the present invention. In this figure, reference numeral 1 is a membrane-type vapor dehumidifier, and a constant space 4 is formed between it and a tube-shaped moisture permeable membrane (polymer membrane) 3 arranged in the center. The moisture permeable membrane 3 is attached to the outer case.
It is manufactured so that it is covered with a sleeve 2. The internal space 3a of the moisture permeable membrane 3 is connected to the sample gas introduction pipe line 5 and the introduced sample gas is introduced into the analyzer 10 through the sample gas outflow pipe line 7.

A comparative gas inlet 2a is provided in the outer case 2.
A reference gas outlet 2b is provided, and a reference gas circulation pipe 9 is connected to the reference gas inlet 2a and the reference gas outlet 2b. Further, a comparative gas introduction valve 6 and a comparative gas outflow valve 8 are arranged in the middle of the comparative gas circulation pipe line 9, and a comparative gas circulation pump 11 and a flow meter 12 are arranged. There is. Further, the comparative gas introduction valve 13 is connected to the comparative gas introduction valve 6, and the comparative gas outflow conduit 15 is connected to the comparative gas outflow valve 8.
The comparative gas (flow rate q _R ) is introduced into the analyzer 10 through the comparative gas outflow line 15. In this way, the comparative gas has a space 4 formed between the moisture permeable membrane 3 and the outer case 2.
And the comparative gas circulation pipe line 9. As the comparison gas, a dry gas containing no water and having removed water, such as air or nitrogen gas, is used. A space (hereinafter referred to as a page side space) 4 formed between the moisture permeable membrane 3 and the outer case 2 with respect to the sample gas flow rate (q _S ) in the membrane vapor dehumidifier 1.
Reference gas flow rate (Q _C) ratio (Q _C / q _S) is preferably set to about 3 to 10 times.

In the gas introducing device of the present invention having the above structure, the moisture vapor pressure of the sample gas introduced into the moisture permeable membrane 3 is P _WS (mmHg), and the moisture of the comparison gas circulating in the comparison gas circulation conduit 9 is Set the vapor pressure to P _WR (mmHg), and
If P _WS > P _WR , the vapor phase equilibrium in which the water vapor pressures in these two flow paths become almost equal near the outlet of the membrane vapor phase dehumidifier 1 as the sample gas and the comparative gas pass through the water permeable membrane 3. And the moisture vapor pressure near the outlet of the membrane vapor dehumidifier 1 is P _WS ′ (mmHg) and the moisture vapor pressure of the comparative gas is P _WR ′ (mmHg), then P _WS ′ =
It becomes P _WR '.

The membrane type vapor phase dehumidifier 1 comprises a moisture permeable membrane 3
Difference in water vapor partial pressure between inside and outside of ΔP _W (ΔP _W = P _WS −P _WR )
Is large, the membrane area of the moisture permeable membrane 3 is large,
If the flow rate (flow rate on the page side) of the comparative gas flowing through the comparative gas circulation path 9 is satisfied, the water molecule permeation efficiency is improved. Since dry gas is used as the reference gas, it is natural that P _WS > P _WR , and the difference ΔP _{W in} water vapor partial pressure is large, so that the permeation efficiency of water molecules is good.

When P _WS > P _WR , the water molecules that permeate through the moisture permeable membrane 3 in the membrane gas phase dehumidifier 1 are water molecules in the sample gas that adhere to the membrane surface and permeate through the polymer membrane. It reaches the surface of the water permeable membrane in the space 4 on the page side. The water molecules that have reached the surface of the water permeable membrane 3 diffuse into the gas atmosphere of the page side space 4 and increase the water vapor pressure of the page side space 4. The moving speed of the water molecules passing through the water permeable membrane 3 is P _WS > P _WR.
It becomes larger as the comparative gas flow rate of the purge side space 4 becomes larger than the sample gas flow rate therein.

As described above, in the gas introducing apparatus of the present invention, the small space-type gas phase dehumidifier 1 is used and the space 4 on the page side is used.
By increasing the flow rate of the reference gas of
The water content of the sample gas near the outlet is increased by increasing the flow rate of the reference gas on the surface (that is, increasing the contact amount of the reference gas), preventing the adsorption of water molecules that have permeated from the sample gas line, and increasing the diffusion rate. Vapor pressure P
It is an approximation of _WS 'and the moisture vapor pressure P _WR ' on the page side. In this case, the temperature of the sample gas is the atmospheric temperature and the temperature of the reference gas is about 40 ° C to 30 ° C below the freezing point, but the temperature near the outlet of the membrane vapor phase dehumidifier 1 is about 20 ° C below the freezing point. Can be vapor-phase equilibrated with. When the moisture vapor pressures of the sample gas and the comparative gas become substantially equal by the above-described actions, the sample gas (flow rate q _S ) and the comparative gas (flow rate q _S ) are respectively supplied from the sample gas outflow conduit 7 and the comparative gas outflow conduit 15. _R ) is made to flow out and introduced into the analyzer 10 for measurement.

FIG. 2 is a block diagram of the second embodiment of the gas introducing device of the present invention. Also in this embodiment, the membrane-type vapor phase dehumidifier 1 is constructed such that the page side space 4 is provided around the moisture permeable membrane (polymer membrane) 3 arranged in the central portion and is covered with the outer case 2. used. The internal space 3a of the moisture permeable membrane 3 is connected to the sample gas introduction pipe line 5 and the introduced sample gas is introduced into the analyzer 10 through the sample gas outflow pipe line 7.

Further, in this embodiment, the sample gas inflow conduit 5 and the sample gas outflow conduit 7 at both ends of the water permeable membrane 3 are further provided.
The three-way valves 14 and 16 are respectively arranged in the pipes to pipe a sample gas circulation pipe line 17, and the pump line 1 is connected to the pipe line 17.
9 and a flow meter 18 are arranged. That is, in this embodiment, a circulation line is also formed in the sample gas flow passage.

A comparative gas inlet 2a is provided in the outer case 2.
A reference gas outlet 2b is provided, and a reference gas circulation pipe 9 is connected to the reference gas inlet 2a and the reference gas outlet 2b. Further, a comparative gas introduction valve 6 and a comparative gas outflow valve 8 are arranged in the middle of the comparative gas circulation pipe line 9, and a comparative gas circulation pump 11 and a flow meter 12 are arranged. There is. Further, the comparative gas introduction valve 13 is connected to the comparative gas introduction valve 6, and the comparative gas outflow conduit 15 is connected to the comparative gas outflow valve 8.
The comparative gas (flow rate q _R ) is introduced into the analyzer 10 through the comparative gas outflow line 15. In this way, the comparative gas circulates between the page side space 4 formed between the moisture permeable membrane 3 and the outer case 2 and the comparative gas circulation conduit 9. It should be noted that the circulation means also includes means using a valve for adjusting the flow rate, a pressure regulator or the like on either the outlet side or the inlet side of the pump.

As described above, in the second embodiment of the gas introducing apparatus of the present invention, the comparative gas line is a circulation line and the sample gas line is also a circulation line. In this way, by increasing the permeation rate of water molecules in the sample gas line through the moisture permeable membrane 3, the gas phase equilibrium between the sample gas and the reference gas at the outlet of the membrane gas phase dehumidifier 1 is realized and its efficiency is increased. be able to.
However, in this case, it is inevitable that the response speed becomes slower as the internal volume of the sample gas circulation line becomes larger. The object of the present invention can be achieved even if only the sample gas flow path is used as the circulation line. In any case, the efficiency becomes irrelevant in the flow direction of the circulation line, whether it is the forward direction or the reverse direction with respect to the flow direction of the sample gas, as the circulation flow rate of the reference gas increases.

[0017]

As described in detail above, according to the gas introduction apparatus of the present invention, even if there is a difference in water concentration between the two series gas lines of the reference gas and the sample gas in the gas analysis,
Since the reference gas in the purge gas line is circulated at a high flow rate, it is possible to increase the permeation and diffusion rate of water molecules on the surface of the water permeable membrane so that gas phase equilibrium is introduced into the analyzer. In particular, according to this gas introduction device, since the membrane type gas phase dehumidifier is used, there is no generation of condensed water or drain, and the response speed when analyzing soluble gas (SO ₂ , NO _2, etc.) is greatly increased. Can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of a gas introduction device of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the gas introduction device of the present invention.

FIG. 3 is a diagram showing a configuration example of a conventional gas introduction device.

[Explanation of symbols]

 1 Membrane Type Gas Dehumidifier 2 Outer Case 2a Reference Gas Inlet 2b Reference Gas Outlet 3 Moisture Permeation Membrane 3a Moisture Permeation Membrane Internal Space 4 Page Space 5 Sample Gas Inlet Pipeline 7 Sample Gas Outlet Pipe Line 6 Comparative gas introduction valve 8 Comparative gas outflow valve 9 Comparative gas circulation line 10 Analyzer 11, 17 Pump 12, 18 Flow meter 13 Comparative gas introduction line 15 Comparative gas outflow line 14, 16 Three-way valve 17 Sample gas circulation line

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiko Fujiwara 2 Higashi-cho, Kichijoin-gu, Minami-ku, Kyoto, Kyoto Inside Horiba, Ltd.

Claims (2)

[Claims] 1. A moisture permeable membrane part, which covers the moisture permeable membrane part so that a constant space is formed between the moisture permeable membrane part and a purge gas inlet and a purge gas outlet. A sample gas introduction conduit and a sample gas outflow conduit for introducing the sample gas into the analyzer are connected to the moisture permeable membrane part of the membrane type dehumidifier consisting of the outer case provided, and the outer case is connected. The purging gas inlet and the purging gas outlet are connected to a purging gas circulation pipe in which a comparative gas introducing valve, a comparative gas outflow valve, and a circulation means are disposed on the way, and further, the comparative gas A gas introducing device, characterized in that a comparative gas outflow conduit for introducing a comparative gas to the analyzer is connected to the outlet. 2. A moisture gas permeable membrane portion and a purge gas inlet and a purge gas outlet are provided to cover the moisture moisture permeable film so that a constant space is formed between the moisture moisture permeable film portion and the moisture moisture permeable film portion. The outer case and the moisture permeable membrane of the membrane dehumidifier are connected to a sample gas introduction line and a sample gas outflow line for introducing the sample gas into the analyzer, and both ends of the moisture permeable membrane are connected. To the three-way valve arranged in the sample gas inflow line and the sample gas outflow line connected to the both ends of the sample gas circulation line in which the circulation means is arranged, and the reference gas introduction port of the outer case. The comparative gas outlet is connected to a purge gas circulation pipe in which a comparative gas introduction valve, a comparative gas outflow valve, and a circulation means are arranged on the way, and the comparative gas is connected to the analyzer at the comparative gas outlet. It is characterized in that a comparative gas outflow line for introducing Gas introduction device.