JPS5975145A - Method for measuring moisture in gaseous sample - Google Patents

Abstract

PURPOSE:To enable exact measurement irrespectively of the change in the sensitivity of a moisture concn. detector by supplying standard gas in sample gas in the preceding stage of the detector in such a way that the output signal of the detector is kept always constant and determining the moisture in the sample gas from the amt. of the standard gas to be supplied. CONSTITUTION:A solenoid valve 7 is closed and a solenoid valve 16 is opened to introduce the dry air which is quantatively humidified by a control pump 14 for supplying humidifying moisture as standard gas having a moisture concn. A into a detector 9 in the case of performing automatic one-point calibration at one point slightly higher than the fluctuating width of the moisture in the sample gas. The output of the detector in this stage is defined as E1. The valve 7 is opened and the valve 16 is closed to introduce sample gas into the detector 9. The pump 14 is controlled with a controller 13 according to the output signal from the detector 9 to supply the standard gas to the sample gas so that the output of the detector attains E1. The moisture concn. corresponding to the moisture in the supplied standard gas is subtracted from the known concn. A, whereby the moisture concn. in the sample gas is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring moisture concentration in a sample gas.

Conventionally, as a method of measuring the water concentration in a sample gas, there is a method of measuring the water content by measuring capacitance as shown in FIG. This method uses two Enoki 1 electric boards (1) (
1) as detection electrodes to form a capacitor, and sample gas (3) is filled between the plates of this capacitor, and the i? This is a method of measuring water content from I-sensitivity, but in order to obtain sufficient detection sensitivity, a water adsorbent (2,., for example, activated alumina) is filled between the electrode plates. Since the amount of water adsorbed in the ladle (2) corresponds to the water concentration in the food waste,
Ji board (1) (by measuring the total capacity between 1
The water concentration in the sample gas is determined. When continuously measuring the water concentration in a sample gas using such a detector, the correspondence between the water concentration and the capacitance of the condenser, that is, the precipitator output, must be determined in advance, as shown in Figure 2 (a). This is possible by setting it as a detection line. That is, a calibration curve (4) (solid line) is set by passing a standard gas with a known moisture concentration through the condenser of the detector and measuring the corresponding output of the detector while changing the moisture concentration. Using this set calibration curve (4), the water concentration of the sample gas can be estimated from the output when the sample gas is passed through the detector.

However, with this measurement method, if the sensitivity of the detector changes, the detector output will change for the reference gas of the same concentration, and the initially set calibration curve will also change, so this must be calibrated periodically. There must be. For example, in Figure 2 (a), the detector output of the reference gas with water content + x A was El according to the initially set calibration curve (4), but the sensitivity of the detector changes and the calibration curve (4) is the inspection N line (5) (dashed line)
Suppose that it becomes E2 because of the change to . If E2 is raised to El by automatic one-point sensitivity calibration, the detection wave: line (5
) Kesugi! e(6) (dotted chain line), which becomes the detector output of E2 when the water concentration C is measured. Then, assuming that the initial setting detection line (4) has been automatically calibrated, when the moisture concentration for the detector output E2 is read, it shows the value of moisture concentration B, which causes an error of "B-0". In this way, in a calibration curve that shows the relationship between water concentration and detector output, it is extremely difficult to correct the calibration curve due to changes in detector sensitivity unless the rate of change of each moisture concentration and detector output always has a constant relationship. Have difficulty.

Therefore, the present invention takes into consideration the above-mentioned conventional drawbacks and improves this. Regardless of the shape of the calibration curve, the water content and detector output can be adjusted at one point that is slightly different from the fluctuation range of the water content in the sample gas. The relationship is based on the standard waste with a known moisture content.
Once the point is calibrated, a measurement method is provided in which the thickness of the water core in the sample gas can be accurately determined regardless of changes in the sensitivity of the detector.

That is, the present invention is designed to measure the moisture concentration in a sample gas so that the output signal from the detector, which shows an output change depending on the moisture concentration, is always constant. In order to ensure that the amount of moisture in the gas in the tatami body gas in the moisture concentration detector is always constant, a standard gas is supplied into the sample gas before the moisture concentration detector, and the amount of moisture in the sample gas is This is a method for measuring moisture in sample waste whose special purpose is to determine the amount.

The present invention will be explained below according to embodiments shown in the drawings. Third
FIG. 6(a) and FIG. 6(b) are diagrams showing basic flow sheets of the measuring device, and the configuration thereof differs depending on the amount of water contained in the standard gas.

In other words, when performing automatic one-point calibration at a point that is slightly higher than the variation range of the moisture content in the sample gas, moisture is supplied into the sample gas before the moisture concentration detector, so that the sample gas at the moisture concentration detector is If the water concentration in the inside is raised to the calibration point γ
It is desirable to do so. Therefore, the supplied standard gas is a gas containing a large amount of water i, and the measuring device has the configuration shown in FIG. 6(a). Conversely, when performing automatic one-point calibration at a point that is slightly lower than the fluctuation range of the moisture content in the sample gas, dry gas is supplied into the sample gas before the moisture concentration detector.
It is desirable that the moisture concentration in the sample gas fed to the moisture concentration detector be reduced to the calibration point. Therefore, the supplied standard gas is a gas with a low moisture content, and the measuring device has the configuration shown in FIG. 6(b).

The present invention will be described below with respect to two different embodiments. That is, in the apparatus shown in FIG. 6(a), (7) is a solenoid valve, and by opening this valve, the sample gas is introduced into the water concentration detector (9). (8
) is a manifold, and 00) is a dehumidifier, which dehydrates the sample gas after measurement. After the measurement and dehydration, the sample gas is discharged by the suction pump (11) through the flow (b).H is a moisture supply control pump for humidifying the sample gas, Before step 9), water for the standard gas is supplied from the sample gas tank. river"
During automatic calibration, open the solenoid valve (16) and close the solenoid valve (7).
By closing the dryer 07), dry air is humidified as a standard gas by the humidifying moisture supply control pump (4) and introduced into the moisture concentration detector (9).

The amount of moisture supplied for this standard gas is determined by the moisture concentration detector (9).
It is controlled by a controller θ3) based on the output signal from the controller θ3).

In addition, in Fig. 6 (b>), the sample gas is introduced, measured, dehydrated and discharged through a filtration process, that is, (7) (s) (
91(io) (The configuration of 1υ(b) is the same as the device shown in FIG. 3(a), but the standard gas supply section has a different configuration.

That is, (1st cell is a metered water supply device, and the amount of water supplied is constant, but the drying gas introduced into the sample gas from the dryer (17) must pass through the drying gas supply amount control section (18). From this, the supply amount is controlled.The dry gas supply amount is determined according to the output signal from the moisture concentration detector (9).
The standard gas in the device shown in FIG. 6(a), which is controlled by a controller (13), is a constant amount of dry gas, and a moisture supply whose amount is controlled by a pump (14) on the humidification moisture supply side. The standard gas in the device shown in FIG. 6(b) is a constant amount of supplied moisture, which is dehumidified by drying gas whose supply amount is controlled by the drying gas supply control section (18). be.

Next, the operation of each embodiment of the present invention based on the above configuration will be explained.
When performing automatic one-point calibration, the device shown in Figure 6(a) (
At this point, the electromagnetic valve (7) is closed, the electromagnetic valve (06) is opened, and the humidifying moisture supply control pump (14) is activated. If the gas is introduced into the detector (9), the detector output is El.
Suppose that it becomes Then, in order to measure the moisture in the sample gas, the solenoid valve (γ) is turned on, and when the solenoid valve (16) is turned on and the sample gas is sent to the detector (9), the detector υ) of E2 Suppose you have gained power. At this time, the humidifying moisture supply control pump (controlled by the controller (13j) controls the sample gas so that the detector output becomes El according to the output signal from the controller (9). Quantitative supply.

Then, by subtracting the moisture concentration in the sample gas from the known concentration A, the moisture concentration in the original sample gas can be found. If the relationship between the water concentration A and the detector output El is maintained at only one point by point calibration, the water concentration in the sample gas can be determined without the need for a calibration curve. Automatic one-point calibration is performed at a point slightly higher than the moisture content variation range II to prevent E2 from reaching El.

When performing automatic one-point calibration at a point slightly lower than the variation range of the water content in the sample gas, in the device M shown in Fig. 6(b), close the solenoid valve (7) and connect the metered water supply device to the dryer. Assume that when dry air quantitatively humidified by the gas supply amount control unit 08) is introduced into the detector (9) as a known reference gas of moisture concentration A, the detector output becomes El. and,
To measure the moisture in the sample gas, open the solenoid valve (a), close the drying gas supply amount control section (e) and constant water supply device (river), and introduce the sample gas to all detectors (9). , 112 detector outputs are obtained.At this time, the controller (dry gas supply amount control unit (e) controlled by the first report) controls the detector output according to the output signal from the detector (9). is El
Dry sludge as a standard gas is supplied to the sample gas in a fixed manner so that Then, by adding the water concentration diluted by this supplied dry gas immersion to the known measurement A, the original water content 1y in the sample gas is determined. In other words, by automatic one-point calibration, the moisture concentration A and the detector output El are 1
If the point-only flash condition is maintained, the water concentration in the sample gas can be determined without requiring calibration i. At this time, automatic one-point calibration is performed at a point slightly lower than the fluctuation range of the water content in the sample gas to prevent El from exceeding E2.

Also, during automatic one-point calibration, there are two methods: introducing a known reference gas with a water concentration A and electrically raising the sensitivity to make the detector output El; and another method changing the known water concentration so that the output is always El. There is. That is, in the latter case, if the temperature of the detector (9) changes and the detector output for a known reference gas of water concentration A does not become El, the detector is electrically adjusted so that the detector output becomes El. Without increasing the sensitivity of (9),
The detector output is set to El by changing the water concentration of the reference gas. If the relationship between the water concentration and the detector output is maintained at this one point, the water concentration in the sample gas can be determined in the same manner as the latter.

Furthermore, in order to make the relationship with conventional measurement methods easier to understand,
The above measurement method will be explained using a calibration curve as follows. In other words, 1 is slightly higher than the fluctuation range of the water content in the sample gas.
Self at the point! In the case of 1iI 11-point calibration, it is assumed that the relationship between the known water concentration A and the detector output E1 at only one point in FIG. 2(a) is maintained by automatic one-point calibration. Then, when the moisture concentration C is fixed in the first set calibration curve (4), if the detector output of E3 is obtained, ]l[i3 is E
Moisture equivalent to "A-0" is supplied as standard gas so that the amount of water becomes 1. This means that if the sensor output of Ell can be obtained when the moisture level is constant in the detection fi fJ (6) corrected to point A according to the sensitivity change of the small instrument, E2 can be changed to El. This is the same result as the amount of moisture supplied by the powder rate gas for "A-○" to achieve the following. That is, the water concentration in the sample gas can be determined by always maintaining the amount of water reduced from A to A, regardless of changes in the calibration curve.

Then, the change in the amount of water in the sample gas i! When automatic one-point calibration is performed at one point slightly lower than the I1 width, it is assumed that the relationship between the known water concentration A and the detector output El at only one point is maintained by the automatic one-point calibration in FIG. 2(b). Then, when the moisture concentration was measured in the first setting check (4), E
If a detector output of 3' is obtained, dry gas as a standard gas is supplied so that E3' becomes El, that is, the moisture content is reduced by "σ-A". This means that the calibration curve corrected to point A (
6) When the moisture concentration σ is measured by &, the output of E2' is obtained. This is the result of the amount of dry gas supplied and its rotation so as to decrease.

That is, irrespective of changes in the calibration curve, the water concentration in the sample gas can be determined by always maintaining the increase in water content from A to A&.

As explained and explained above, in the present invention, the relationship between the moisture concentration and the output of the moisture concentration detector is automatically calibrated at only one point using a reference gas with a known moisture concentration, and the sample gas can be accurately calibrated regardless of changes in the sensitivity of the detector. Since the moisture concentration of the instep was determined,
This eliminates the need for a calibration curve, which was necessary in the conventional measurement method that directly determines the water concentration in the sample gas. Following,
It also eliminates the need for complicated calibration curve corrections due to changes in detector sensitivity, and the water concentration in the sample gas can be determined more accurately than before. Furthermore, since a calibration curve is not required, the effort required for measurement is also reduced.

[Brief explanation of the drawing]

Figure 1 is a side cross-sectional view of a condenser for detecting moisture concentration in a device for measuring moisture concentration in sample gas, and Figure 2 (a) and 2.
FIG. 6(b) is a calibration curve showing the relationship between water concentration and the output of the water concentration detector, and FIGS. 6(a) and 6(b) are block diagrams of basic flow sheets of an embodiment of the measuring device. (9)...Moisture concentration detector, (13)...Controller,
(14)...Moisture supply control pump for humidification, 04...
Quantitative water supply device, ni)... water tank, (16)... solenoid valve,
(17)...Dryer, (2))...Drying gas supply amount control unit. Patent Applicant Xiadu Electronics Industry Co., Ltd. Agent Jiangyuan Province Joint Pressure Hara Hideki 1 Diagram 2 Diagram

Claims (1)

[Claims] (1.1 In a sample gas moisture concentration measurement device, the output signal from the detector, which shows an output change for each water molecule Jh j+, is always kept constant. In order to ensure that the amount of water in the sample gas detected by the moisture concentration detector is always constant even if the concentration changes, a standard gas is supplied into the sample gas before the moisture concentration detector, and the amount of supplied standard gas is A method for measuring moisture in a sample gas, characterized by determining the amount of moisture in the sample gas.