JP4247493B2 - Humidity measuring method and humidity measuring device - Google Patents

Description

  The present invention is a method and apparatus for measuring absolute humidity and relative humidity of a gas under all conditions concerning humidity measurement.

  Conventionally, absolute humidity measurement methods include a weighing method in which moisture is absorbed and absorbed in a hygroscopic material, a mass measurement method, a dew point measurement method in which the dew point is measured by optical measurement, etc., and an electric capacity by moisture adsorption There are methods such as a capacitance method, a resistance method, and a heat conduction method for measuring changes in electrical resistance and heat conduction. There is a moisture meter as a measuring device for relative humidity.

On the other hand, as a method for measuring the viscosity of a gas, there is no method for measuring only the viscosity, and there is only a method for measuring a change that the viscosity of the gas gives to the pressure. In general, in measuring the viscosity of a fluid, the viscosity is obtained by measuring a pressure difference, including an Ostwald viscometer, which is the most typical viscometer. In addition, in the case of a gas that does not flow in a certain direction, the viscosity is obtained by measuring the friction force generated by the collision of the gas with the surface of the gas. Is the easiest to use.
Edited by the Japan Society of Mechanical Engineers, "Humidity / moisture measurement and environmental monitoring", Gihodo Publishing, 1992 Humidity Measurement / Sensor Study Group, “Humidity Measurement / Sensor Manual” A Guide to the Measurement of Humidity, (The Institute of Measurement and Control, UK, 1996), (Japanese translation: Kotaro Kobayashi, “Guidelines for Humidity Measurement”, Techne Yoko, 1998)

  Of the above humidity measurement methods, the weighing method and dew point measurement method require sampling and cooling processes to complete the measurement, so the overall measurement time is very long and the state changes in seconds. In such a case, it is not possible to perform measurement following such environmental changes. Another problem with optical dew point measurement is the pressure loss in the piping and the large size of the equipment. In the method using moisture adsorption such as capacity type, resistance type, heat conduction type, etc., the time order of moisture adsorption / desorption is still long, so it cannot follow the change in seconds, and it occurs at the same time during moisture adsorption / desorption In addition to being affected by other impurities, the background has aged due to the influence of the history due to repeated adsorption and desorption, and thus has the disadvantage that the error becomes large. In addition, the moisture meter needs timely water replenishment maintenance.

  The present invention solves these conventional problems and enables high-time resolution measurement in units of seconds or less, and converts the absolute humidity value directly into the relative humidity by using the measured temperature and derives it. An object of the present invention is to provide a simple and compact, low-cost, maintenance-free humidity measuring method and apparatus.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means.
A method and apparatus for deriving absolute humidity by measuring the pressure of a system with a pressure gauge that is humidity calibrated and depending on physical property values, and comparing the pressure indication value with a separately prepared calibration curve.
A method and apparatus for deriving absolute humidity by measuring the system pressure with a quartz-vibration pressure gauge or spinning rotor gauge whose humidity is calibrated, and comparing the pressure indication value with a separately prepared calibration curve.
A method and apparatus for creating a calibration curve by comparison with absolute pressure measured simultaneously.
A method and apparatus for measuring absolute pressure simultaneously with measurement of a quartz vibration type pressure gauge or a spinning rotor gauge and deriving absolute humidity using a calibration curve prepared in advance.
A method and apparatus for determining relative humidity from the temperature measured simultaneously with the absolute humidity determined above.
The present invention has been made based on this finding.

That is, the present invention
(1) An absolute humidity measuring method for deriving absolute humidity by measuring the pressure of the system with a calibrated pressure gauge depending on the physical property value,
(2) The absolute humidity measurement method according to (1), wherein the physical property value is viscosity, and a quartz vibratory pressure gauge or a spinning rotor gauge is used as a pressure gauge depending on the physical property value,
(3) The absolute humidity measurement method according to (1), wherein the calibration is an absolute humidity calibration performed using absolute humidity calculated separately from temperature and relative humidity;
(4) The absolute humidity measuring method according to (1), wherein the calibration is humidity calibration performed by measuring an absolute pressure.
(5) A method of measuring the absolute humidity according to (4), wherein a diaphragm pressure gauge is used to measure the absolute pressure.
(6) Relative humidity measurement method for deriving relative humidity from the absolute humidity measured using the absolute humidity measurement method described in (1) and the temperature measured simultaneously,
(7) The relative humidity measuring method according to (6), wherein the physical property value is viscosity, and a quartz vibratory pressure gauge or a spinning rotor gauge is used as a pressure gauge depending on the physical property value,
(8) an absolute humidity measuring device having a calibrated pressure gauge depending on a physical property value for measuring the pressure of the system used for deriving the absolute humidity;
(9) The absolute humidity measuring device according to (8), wherein the physical property value is viscosity, and a quartz vibratory pressure gauge or a spinning rotor gauge is provided as a pressure gauge depending on the physical property value,
(10) An absolute humidity measuring device according to (8), further comprising a temperature measuring element for measuring a temperature for calculating absolute humidity and a relative humidity separately used for absolute humidity calibration,
(11) An absolute humidity measuring device according to item (8), comprising an absolute pressure gauge for measuring absolute pressure used for humidity calibration;
(12) The absolute pressure measuring element is a diaphragm pressure gauge, the absolute humidity measuring device according to (11), the absolute humidity measuring device according to (13) and (8), and the absolute measuring device And a relative humidity measuring device comprising a temperature probe for measuring the temperature at the same time as measuring the pressure of the system, and (14) a pressure depending on the physical property value, wherein the physical property value is viscosity. The relative humidity measuring device according to the item (13) is provided with a quartz vibration type pressure gauge or a spinning rotor gauge as a measuring element.

In the present invention, only the pressure is actually measured when measuring the humidity. Therefore, it is possible to measure the humidity in real time in any atmosphere in any measurement environment, and to perform high-speed measurement in units of seconds or less. .
Moreover, since the change over time of the indicated value of the pressure gauge is small, it can be stably measured over a long period of time.
Furthermore, since the value obtained from the measurement with the pressure gauge indicates the absolute humidity as it is, its derivation and display are simple, so this value can be used to directly control the absolute humidity of the atmospheric gas at any temperature. Is also easy.

  The present invention is a method and apparatus for measuring absolute humidity and / or relative humidity that derives absolute humidity by measuring the pressure of the system with a calibrated pressure gauge that depends on physical property values. Specifically, for example, there are a method and an apparatus for determining absolute humidity and / or relative humidity by measuring viscosity, thermal conductivity, density, molecular weight, and physical property values of the system as a function thereof and separately calibrating them. The physical property value is preferably viscosity. In the present invention, “system” means an atmospheric gas containing water. Although the gas used as object is not limited, For example, air, nitrogen, argon, oxygen etc. are mentioned. “Calibration” is, for example, humidity calibration, preferably absolute humidity calibration. This calibration may be performed in advance or may be performed after pressure measurement, but is preferably performed in advance for speed of measurement.

In the present invention, more preferably, the pressure of the system is measured by using a pressure gauge that is sensitive to a physical property value such as viscosity and calibrated with absolute humidity as a pressure gauge depending on the physical property value, and the pressure indication value is obtained. It is a method of deriving absolute humidity by conversion. In the present invention, “sensitive to a physical property value” means that the pressure gauge indicated value changes depending on the physical property value of the substance.
As the method of absolute humidity calibration, for example, various absolute humidity states are created, the temperature and relative humidity are measured with an existing thermometer, a calibration curve is created, and the calibration curve is converted. Absolute humidity is obtained and the absolute humidity indicated by the pressure gauge sensitive to the physical properties at that time is assigned.
In addition, it is preferable to simultaneously measure absolute pressure using a pressure gauge that is sensitive to physical properties and a pressure gauge that does not depend on physical properties, and to correlate with physical properties such as viscosity by removing the influence of pressure. The absolute humidity is calibrated by obtaining the value.
Once the above absolute humidity calibration is performed, it is not necessary to perform the calibration thereafter, and the absolute humidity can be directly derived in real time corresponding to the environmental change in seconds or less by only measuring with a pressure gauge sensitive to physical properties.

Also, when the pressure change in the system is large, measure the absolute pressure with an absolute pressure gauge such as a diaphragm pressure gauge to eliminate the effect of pressure, and more accurately measure the quantity depending on the physical property value, and Can be obtained. For example, there is no method for measuring only the viscosity of a gas, and it is the easiest method to use a pressure gauge to measure the viscosity of a gas that does not flow in a fixed direction. Except for the effect, the amount dependent on viscosity can be measured more accurately and the absolute humidity can be determined.
In addition, if the temperature is measured at the same time using the pressure gauge sensitive to physical properties calibrated at the above absolute humidity, the relative humidity can be derived in real time according to environmental changes in seconds or less as well. .

  Examples of pressure gauges sensitive to physical properties include known quartz vibration type pressure gauges (quartz friction vacuum gauges) and spinning rotor gauges that use viscosity (friction), thermocouple vacuum gauges and Pirani vacuum gauges that use heat conduction. In addition, a Knudsen vacuum gauge or the like can be appropriately selected and used. For example, a known hot cathode ionization vacuum gauge, cold cathode ionization vacuum gauge, radiation ionization vacuum gauge or the like using an ionization phenomenon can also be used. These probes can be used properly depending on the gas properties such as flammability and explosiveness, the concentration and pressure of the target mixed gas.

Examples of pressure gauges used for humidity calibration that do not depend on physical property values are sensitive only to the pressure of a known liquid column differential vacuum gauge, compression vacuum gauge, diaphragm vacuum gauge, Bourdon tube vacuum gauge, etc. It changes depending on the pressure and pressure, and the physical quantity such as the frictional force that the moving solid receives from the gas, the thermal conductivity change from the solid to the gas, and the heat generated by the decomposition when the gas reacts near the solid surface. Among them, a pressure gauge whose physical quantity changes can be mentioned.
Any thermometer can be used as a temperature gauge used for absolute humidity calibration and relative humidity derivation.

Preferred embodiments of the present invention will be described below with reference to the drawings.
In the drawings, the same symbols indicate the same items.

  FIG. 1 is an explanatory diagram for schematically explaining the main part of the absolute humidity measuring device of the present invention. As shown in FIG. 1, this apparatus includes a pressure measuring element (hereinafter referred to as “pressure / physical value measuring element” 1) 1 depending on a physical property value. In the method of the present invention using the apparatus of FIG. 1, the display pressure changes depending on the physical properties such as the viscosity of the gas, and the measurement is performed with the pressure / physical property measuring element 1 whose properties are known in advance, and the humidity calibration is performed in advance. Then, a conversion 11 is performed using a calibration curve (described later), and an absolute humidity 7 is derived as indicated by an arrow.

  FIG. 2 is an explanatory diagram schematically illustrating an embodiment in which a quartz vibration type pressure gauge 2 is used as the pressure / physical property value measuring element 1 in FIG. Also in the apparatus of FIG. 2, the measurement is performed by the quartz vibration type pressure gauge 2, the conversion 11 is performed using a calibration curve prepared in advance as indicated by the arrow, and the absolute humidity 7 is derived. In this case, a spinning rotor gauge or the like can be used as appropriate in place of the quartz vibration type pressure gauge 2 according to the range of the pressure to be measured.

The characteristics of this quartz vibration type pressure gauge 2 are shown in FIG. This is because, for example, as shown in Table 1, the molecular weight and the viscosity coefficient differ depending on the type of gas, so that in Ar, He, and H ₂ , the indication value of the crystal vibration type pressure gauge shows an apparently different pressure. It is shown. This is because the quartz vibratory pressure gauge has a frictional force with the gas received by the quartz crystal in contact with the gas, in the region where the pressure is a viscous flow, it is half the product of the molecular weight of the gas and the viscosity coefficient of the gas. It comes from being proportional. This quartz-vibration pressure gauge operates at room temperature and does not react with the gas to be measured, so that the gas to be measured is not consumed by the measurement, and the combustible gas can be detected and measured safely.

  FIG. 4 shows the pressure indication value of the crystal vibration type pressure gauge 2 when the absolute humidity is changed using the apparatus of FIG. As shown in FIG. 4, the pressure indication value (kPa) Y of the quartz vibration type pressure gauge 2 is linearly related to the absolute humidity (mass ratio per kg of dry air [kg / kg (DA)]) X ( R = 0.99616), and if this FIG. 4 is a calibration curve (Y = −78X + 102), as indicated by the arrow in FIG. Absolute humidity can be derived by converting to absolute humidity.

  When the change in absolute pressure of the measurement target is large, it is possible to offset the effect of pressure by measuring the absolute pressure with an absolute pressure gauge such as a diaphragm vacuum gauge, and increase the accuracy of the required physical property value. is there. FIG. 5 is an explanatory diagram schematically illustrating an apparatus for performing such measurement. The apparatus of FIG. 5 includes an absolute pressure gauge 3 and a pressure / physical value gauge 1, and each of the absolute pressure gauge 3 and the pressure / physical value gauge 1 measures the pressure. The ratio 12 is converted by a calibration curve 12 and the absolute humidity 7 is derived.

  FIG. 6 shows the apparatus of FIG. 5 in which a diaphragm vacuum gauge 4 is used as the absolute pressure gauge 3 and a quartz vibration type pressure gauge 2 is used as the pressure / physical property gauge 1. In the apparatus of FIG. 6, the pressure is measured by each of the diaphragm vacuum gauge 4 and the quartz-vibration pressure gauge 2, and the conversion 12 is performed by the calibration curve of the ratio between the two as indicated by the arrow to derive the absolute humidity 7. To do.

  FIG. 7 shows the ratio between the pressure indication value of the quartz vibration type pressure gauge 2 and the indication value of the diaphragm pressure gauge 4 when the absolute humidity is changed using the apparatus of FIG. As shown in FIG. 7, the value X of the ratio between the quartz vibration type pressure gauge 2 and the indication value of the diaphragm pressure gauge 4 is absolute humidity (mass ratio per kg of dry air [kg / kg (DA)]) Y 7 is a calibration curve (Y = −0.78X + 1.03) and measured with the diaphragm pressure gauge 4 and the quartz-vibration pressure gauge 2, and the crystal The absolute humidity 7 can be derived by converting 12 the value of the ratio between the vibration pressure gauge indication value and the diaphragm pressure gauge indication value using a calibration curve.

FIG. 8 shows another embodiment of the present invention, in which the spinning rotor gauge 5 is further connected to the apparatus of the embodiment shown in FIG. 6, and the apparatus configuration of the absolute humidity measuring apparatus constituted by three types of vacuum gauges. An example is shown. As described above, the diaphragm pressure gauge 4 measures the absolute pressure regardless of the type of gas, and the quartz-vibration pressure gauge 2 is sensitive to both the viscosity and molecular weight physical properties and pressure of the gas, and the working pressure range is 10 ^{−. From 2} pa to 10 ⁻⁵ pa, the spinning rotor gauge 5 is sensitive to both the viscosity and molecular weight physical properties and pressure of the gas as in the quartz vibration type pressure gauge 2, and the operating pressure range is from 10 ⁻⁵ Pa. 1 Pa. As described above, the absolute humidity 7 can be obtained by converting 12 the ratio of the indication values of the quartz vibration type pressure gauge 2 and the spinning rotor gauge 5 to the indication value of the diaphragm pressure gauge using a calibration curve.

FIG. 9 shows an example of the characteristics of the spinning rotor gauge 5. The measuring element can measure a region having a higher degree of vacuum than the quartz vibration type pressure gauge 2. Here, the relationship between the indicated pressure and true pressure of air, water (H ₂ O), Ar, Kr, Xe, Ne, He, H ₂ , Freon (trade name), CO ₂ is shown. As seen in the figure, in the pressure region above atmospheric pressure, the indication value in the spinning rotor 5 has a significant difference between air and water, and can be converted to absolute humidity.
Therefore, in FIG. 8, the indicated value of the spinning rotor gauge 5 is used in the region where the degree of vacuum is high, and the indicated value of the crystal vibration type pressure gauge 2 is used in the low region, and both values are used in the effective range of both values. The absolute humidity of the gas atmosphere can be obtained by removing the influence of the pressure by arithmetic processing.

  FIG. 10 is a schematic explanatory view of an apparatus for performing measurement using the pressure / physical property measuring element 1 and the temperature measuring element 6 and performing a measurement method for deriving the relative humidity 8 by performing conversion 13 from the values obtained by both. is there.

  In the embodiment of FIG. 11, the pressure / physical property measuring element 1 in FIG. 10 uses the indicated value of the spinning rotor gauge 5 in the high vacuum region, and uses the quartz vibration pressure gauge 2 in the low region, The absolute humidity 8 of the gas atmosphere can be obtained by measuring 13 using the probe 6 and converting 13 from both values.

  FIG. 12 is a diagram showing still another example of the apparatus configuration of the apparatus shown in FIG. 10. As shown in this figure, the diaphragm pressure gauge 4 for measuring the absolute pressure is replaced by a quartz vibration type pressure gauge 2, a spinning rotor gauge 5, Even if the fluctuation of the absolute pressure is large by connecting the temperature measuring element 6 and performing the conversion 13 from the values of the spinning rotor gauge 5 and the temperature measuring element 6 and the diaphragm pressure gauge 4 and the temperature measuring element 6 respectively. It is possible to measure the relative humidity 8 with good.

  An example of the time response characteristic of humidity measurement common to all the above embodiments is shown in FIG. The time until the indicated value of the quartz vibration type pressure gauge indicated by a circle with respect to the absolute humidity change indicated by the solid line reaches 90% of the saturation indicated value is about 600 ms at the time of rising shown in FIG. Since it is about 900 ms at the time of falling shown in FIG. 13 (b), the humidity measurement method and apparatus according to the present invention can perform high time resolution humidity measurement in units of seconds or less.

It is explanatory drawing which illustrates the principal part of the apparatus of this invention typically. It is explanatory drawing which illustrates typically one embodiment of the apparatus of this invention. It is a graph which shows the characteristic of an example of the crystal vibration type pressure gauge used with the apparatus shown in FIG. It is a figure (calibration curve) showing the relationship between the pressure instruction | indication value of an example of the crystal vibration type pressure gauge used with the apparatus shown in FIG. 2, and absolute humidity. It is explanatory drawing which illustrates typically the apparatus of another embodiment of this invention. It is a schematic diagram which shows an example of a measurement apparatus structure of the apparatus in FIG. FIG. 7 is a diagram (calibration curve) showing an example of a relationship between a ratio of a pressure indication value of a crystal vibration type pressure gauge to a pressure indication value of a diaphragm pressure gauge and absolute humidity used in the example shown in FIG. 6 of the present invention. It is a schematic diagram which shows an example of the measuring equipment structure of another embodiment of this invention. It is a characteristic view of an example of the spinning rotor gauge used in the example shown in FIG. 8 of the present invention. It is explanatory drawing which illustrates typically the apparatus of another embodiment of this invention. It is a schematic diagram which shows an example of the measuring equipment structure of the apparatus in FIG. It is a schematic diagram which shows another example of the measurement apparatus structure of the apparatus in FIG. It is a figure showing an example of the response time with respect to an absolute humidity change in the embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure / physical property measuring element 2 Crystal vibration type pressure gauge 3 Absolute pressure measuring element 4 Diaphragm vacuum gauge 5 Spinning rotor gauge 6 Temperature measuring element 7 Absolute humidity 8 Relative humidity 11 Conversion by calibration curve (derivation)
12 Conversion of both ratios using a calibration curve 13 Conversion from both values

Claims (6)

A calibration curve between the absolute humidity calculated from the measurement or the absolute humidity calculated from the temperature and relative humidity and the measurement indication value of the pressure gauge at the absolute humidity is prepared in advance, and the system targeted by the pressure gauge In an absolute humidity measurement method for measuring the pressure of the system, converting the measured value with the calibration curve, and deriving the absolute humidity of the system,
The pressure gauge is a pressure gauge whose pressure gauge indication value changes depending on the physical property value, and uses a quartz vibration type pressure gauge or a spinning rotor gauge, and the physical property value is molecular weight and viscosity. absolute humidity measurement method to be. A calibration curve is prepared in advance between the absolute humidity calculated by measurement or the absolute humidity calculated from the temperature and relative humidity, and the ratio of the measurement indication value of the pressure gauge at the absolute humidity to the absolute pressure, and the pressure gauge And an absolute humidity measuring method for measuring the pressure of the target system with an absolute pressure gauge, converting the ratio of the measurement indication value of the pressure gauge to the absolute pressure with the calibration curve, and deriving the absolute humidity of the system In
The pressure gauge is a pressure gauge whose pressure gauge indication value changes depending on the physical property value, using a quartz vibration type pressure gauge or a spinning rotor gauge, the physical property value is molecular weight and viscosity,
The absolute pressure is measured by using a diaphragm pressure gauge which is an absolute pressure gauge . A relative humidity measuring method, wherein the relative humidity is derived from the absolute humidity measured using the absolute humidity measuring method according to claim 1 and the temperature measured simultaneously . The measurement value obtained by measuring the pressure of the target system with a pressure gauge, the absolute humidity calculated from the absolute humidity or temperature and relative humidity obtained by measurement, and the pressure at the absolute humidity In the absolute humidity measuring device that derives the absolute humidity of the system by converting based on the calibration curve with the measurement instruction value of the probe,
The pressure gauge is a gauge whose pressure gauge indication value changes depending on the physical property value, and is a quartz vibration type pressure gauge or a spinning rotor gauge, and the physical property value is molecular weight and viscosity. Absolute humidity measuring device. The measurement value obtained by measuring the pressure of the target system with a pressure gauge, the absolute humidity calculated from the absolute humidity or temperature and relative humidity obtained by measurement, and the pressure at the absolute humidity In an absolute humidity measuring device that derives the absolute humidity of the system by converting based on a calibration curve with the ratio of the measurement indication value of the measuring element to the absolute pressure,
The pressure gauge is a pressure gauge in which an indication value of the pressure gauge changes depending on a physical property value, and is a quartz vibration type pressure gauge or a spinning rotor gauge, and the physical property value is a molecular weight and a viscosity,
The absolute pressure is measured using a diaphragm pressure gauge which is an absolute pressure gauge. 6. A relative humidity measuring device capable of deriving a relative humidity from an absolute humidity measured using the absolute humidity measuring device according to claim 4 and a temperature measured at the same time.

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