JPH08201238A - Moisture meter - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Accurate measurement of water content is possible even when the sample gas contains a substance that interferes with the sensitivity of the moisture sensor and is adsorbed by the desiccant. Provide a moisture meter. [Structure] The sample gas supplied from the sample supply port ET is distributed to the pipelines A and B, the sample gas supplied to the pipeline A directly reaches the solenoid valve 2, and the sample gas supplied to the pipeline B is The solenoid valve 3 is reached via the moisture absorber 4. Here, in the moisture absorber 4, the sample gas is the permeation tube 4a.
When passing through the inside, only the contained water selectively permeates the tube 4a and flows out to the outer periphery thereof, and is absorbed by the filled desiccant 4b, so that only the water in the sample gas is removed. Dry gas is produced. And the solenoid valve 2,
3 shows the line B when the line A is connected to the moisture sensor 1.
To the bypass outlet BEX, and the conduit A is the bypass outlet B.
The conduit B is alternately switched to the moisture sensor 1 when connected to the EX.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture meter for measuring moisture in gas in various industrial processes.

[0002]

2. Description of the Related Art Generally, a moisture meter for continuously measuring moisture in a gas in various industrial processes is used in, for example, gas production industry, semiconductor industry, metal heat treatment industry, petrochemical industry, ceramic industry, biochemistry, etc. In the field, it is used to control the water content of process gases.

[0003] In such a moisture meter, at present, there is no substance that is sensitive only to moisture and is not sensitive to other coexisting parts. Therefore, in fact, coexisting components other than moisture, especially halides, are not present. A substance that is sensitive but has a selectively superior sensitivity to moisture is used.

Therefore, in the conventional moisture meter, in order to remove the influence of such coexisting components, the sample gas and the dry gas from which the moisture has been removed are alternately supplied to the moisture sensor, and the difference in their outputs is used. What measures the water content in gas is used.

That is, FIG. 4 is a schematic view of such a conventional moisture meter. The sample gas supplied from the sample supply port ET is distributed to the pipeline A and the pipeline B, the sample gas supplied to the pipeline A reaches the solenoid valve 12 as it is, and the sample gas supplied to the pipeline B is molecular. A desiccant 14b such as sieves or phosphorus pentoxide passes through the moisture absorber 14 filled inside to become a dry gas and reaches the solenoid valve 13. Then, by alternately switching the solenoid valves 12 and 13, the moisture sensor 1
The sample gas and the dry gas are alternately supplied to 1, and the output difference of the moisture sensor 11 is calculated by a calculation means (not shown) or the like to measure the amount of moisture in the gas.

As a result, when the sensitivity of the moisture sensor 11 is interfered with by substances other than moisture contained in the sample gas, for example, the moisture sensor 11 is of a crystal oscillator type which measures a change in oscillation frequency, and crystal vibration Even when the sample gas contains a substance that is adsorbed by the moisture-sensitive film on the child, the interference by the substance is canceled out, and the amount of moisture can be accurately measured.

[0007]

However, in the moisture absorber 14 used in the conventional moisture meter, the sample gas directly passes through the desiccant 14b such as molecular sieves or phosphorus pentoxide filled in the moisture absorber 14. Therefore, the desiccant 14 such as molecular sieves or phosphorus pentoxide
In some cases, the sample gas was brought into direct contact with b, and not only water but also substances in the sample gas that interfere with the water sensor 11 were adsorbed. In this case, the amount of the substance interfering with the moisture sensor 11 differs between the sample gas passing through the flow channel A and the sample gas passing through the flow channel B by the amount adsorbed by the desiccant 14b, and thus the above-mentioned offsetting effect is obtained. Does not work, and there is a problem that the amount of water cannot be measured accurately.

Therefore, the present invention was devised to solve the above-mentioned problems, and is a case where the sample gas contains a substance that interferes with the sensitivity of the moisture sensor and is adsorbed by the desiccant. Also aims to provide a moisture meter capable of more accurately measuring the moisture content.

[0009]

A moisture meter according to the present invention is provided with gas switching means for alternately switching and supplying a sample gas and a dry gas generated by a moisture absorber that absorbs moisture from the sample gas. In a moisture meter provided with a moisture sensor arranged in a gas flow path, the moisture absorber is a permeation tube through which the sample gas passes, and the permeation tube permeates the permeation tube and flows out to the outer periphery thereof. It is characterized by having a desiccant or a dry gas that absorbs water.

[0010]

The operation of the present invention will be described with reference to FIG. The sample gas supplied from the sample supply port ET is distributed to the pipelines A and B, and the sample gas supplied to the pipeline A is directly connected to the solenoid valve 2
And reaches the solenoid valve 3 via the moisture absorber 4. Here, in the water absorber 4,
When the sample gas passes through the permeation tube 4a, only the water contained therein selectively permeates the tube 4a and flows out to the outer periphery thereof to fill the desiccant 4b.
As a result, the dry gas in which only the water content in the sample gas is removed is generated. Then, the solenoid valves 2 and 3 (gas switching means) connect the pipeline B to the bypass discharge port BEX when the pipeline A is connected to the moisture sensor 1, and the pipeline A to the bypass discharge port BEX. By alternately switching the pipe line B to the moisture sensor 1 at the time, the sample gas and the dry gas in which only moisture is completely removed from the sample gas are alternately guided to the moisture sensor 1, An accurate water content is measured from the output difference of the water content sensor 1.

[0011]

EXAMPLE An example of a moisture meter according to the present invention is shown in FIGS.
It will be described based on.

FIG. 1 is a schematic diagram of a moisture meter according to the present invention, in which a sample supply port ET is connected to a gas flow path or the like in various industrial processes and the like, and a sample gas whose moisture content is to be measured is fed to the moisture meter. Supply. The supplied sample gas is distributed to the conduit A directly connected to the solenoid valve 2 and the conduit B connected to the solenoid valve 3 via the moisture absorber 4.

The moisture absorber 4 absorbs moisture from a sample gas and produces a dry gas, and is a permeation tube 4a (for example, NAFLON manufactured by Permapure Co., Ltd.) composed of a permeation film that selectively permeates only moisture. Tube) and a desiccant 4b such as molecular sieves or phosphorus pentoxide. FIG. 2 is a schematic view showing an example of the moisture absorber 4, in which a permeation tube 4a is spirally arranged in a container 4c in which a sample inlet 4d to which a sample gas is supplied and a sample outlet 4e from which a sample gas is discharged are formed. The tube 4a in the container 4c is filled with a desiccant 4b such as molecular sieves or phosphorus pentoxide around the outer periphery of the tube 4a. As a result, in the sample gas that has passed through the permeation tube 4a, only the contained water selectively permeates from the permeation film, flows out to the outer periphery thereof, and is absorbed by the filled desiccant 4b. Only water can be removed from the sample gas.

By thus arranging the permeation tube 4a in a spiral shape, the outer peripheral area of the permeation tube 4a can be increased, so that efficient removal of water from the sample gas is possible. Becomes

The solenoid valves 2 and 3 connected to the pipelines A and B are
The pipelines A and B are connected to the moisture sensor 1 and the bypass outlet B, respectively.
The switch is connected to the EX, and the sample gas or the dry gas is supplied to the moisture sensor 1 or discharged from the bypass discharge port BEX depending on each connection position.

The moisture sensor 1 is, for example, of a quartz oscillation type in which a film sensitive to moisture is formed on the surface of the quartz oscillator, and measures the frequency of the quartz oscillator which changes according to the amount of attached moisture. It is possible to measure the amount of water in the sample gas that has passed through.

Next, the operation of the moisture meter constructed as above will be described. The sample gas supplied from the sample supply port ET is distributed to the pipelines A and B, and the sample gas supplied to the pipeline B passes through the moisture absorber 4. Here, the water absorber 4
Then, when the sample gas passes through the permeation tube 4a, only the contained water is selectively contained in this tube 4a.
The desiccant 4 that permeates a and flows out to the outside and is filled
Since it is absorbed by b, only moisture is completely removed from the sample gas that has passed through the moisture absorber 4 to become a dry gas. And
The solenoid valves 2 and 3 are manually or by a control means (not shown),
When the conduit A is connected to the moisture sensor 1, the conduit B is connected to the bypass outlet BEX, and the conduit A is connected to the bypass outlet B.
When it is connected to the EX, the line B is alternately switched so as to be connected to the moisture sensor 1, and the sample gas and the dry gas in which only moisture is completely removed from the sample gas are alternately guided to the moisture sensor 1. Then, the sample is discharged from the sample discharge port EX. It should be noted that although this switching cycle depends on the characteristics of the moisture sensor 1, if it is performed at intervals of, for example, 30 seconds, stable measurement becomes possible. Then, an arithmetic means (not shown) or the like calculates an accurate amount of water in the sample gas from the difference between the measured values of the sample gas and the dry gas in the water sensor 1.

As described above, according to the present invention, since it is possible to produce a dry gas in which only water is accurately removed from the sample gas, it interferes with the sensitivity of the water sensor and is adsorbed by the desiccant. Even when the substance is contained in the sample gas, it is possible to measure the water content of the sample gas in an extremely accurate manner.

The moisture absorber 4 according to the present invention is not limited to the structure shown in FIG. 2 in which the outer periphery of the permeation tube 4a is filled with the desiccant 4b. For example, the moisture is extracted from the sample gas and the sample gas. A moisture meter provided with gas switching means for alternately switching and supplying the dry gas generated by the absorbing moisture absorber, and a moisture sensor arranged in the flow path of the supplied gas, wherein the moisture absorber Is a permeation tube through which a sample gas passes, and the container is provided with a gas supply port and a gas exhaust port connected to a space formed by the outer periphery of the permeation tube and the inner surface of the container. Alternatively, the dry barge gas may be supplied from the gas supply port and discharged from the gas discharge port through the space.

That is, FIG. 3 is a schematic view of such a modification of the present invention, in which a container 4c is provided with a sample inlet 4d for supplying a sample gas and a sample gas passing through a permeation tube 4a '. Sample outlet 4e,
And the outer periphery of the permeation tube 4a 'and the container 4c
A gas supply port 4f and a gas discharge port 4g connected to a space 4h formed by the inner surface are formed. Then, the dry purge gas PG is supplied from the gas supply port 4f,
After passing through the space 4h, the gas is discharged from the gas discharge port 4g.

With the above structure, the sample gas that has passed through the permeation tube 4a 'is penetrated only by the moisture in the sample gas from the permeation film and flows out to the outer circumference of the tube 4a', and faces the outer circumference. Since the purge gas PG flowing through the space 4h is absorbed and discharged, it is possible to effectively remove the water, and the work such as the replacement of the desiccant becomes unnecessary, and the maintenance becomes very easy.

[0022]

According to the present invention, since the dry gas from which only water is accurately removed can be generated from the sample gas, the substance that interferes with the sensitivity of the water sensor and is adsorbed by the desiccant is the sample gas. Even if the water content is included in, it is possible to measure the water content extremely accurately.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a moisture meter according to the present invention.

FIG. 2 is a schematic view showing an example of a moisture absorber according to the present invention.

FIG. 3 is a schematic view showing an example of a moisture absorber according to the present invention.

FIG. 4 is a schematic view of a conventional moisture meter.

Claims (1)

[Claims] 1. A gas switching means for alternately switching and supplying a sample gas and a dry gas generated by a moisture absorber that absorbs moisture from the sample gas, and a moisture sensor arranged in a flow path of the gas to be fed. In the moisture meter, the moisture absorber has a permeation tube through which the sample gas passes, and a desiccant or a dry gas that permeates the permeation tube and absorbs the moisture flowing out to the outer periphery thereof. Moisture meter characterized by.