JP2006058201A - Heat conduction type gas analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat conduction type gas analyzer capable of regulating automatically environments inside a reference gas seal chamber and a measuring gas chamber to be brought into the same, and capable of obtaining an accurate measured value without requiring an expensive correction device using a CPU or the like to be used. <P>SOLUTION: The environment inside the reference gas seal chamber is formed to correspond to the environment inside the measuring gas chamber. The reference gas seal chamber is formed to make a volume variable, and is formed to conform the inside environment thereof with the inside environment of the measuring gas chamber, by the volume variation. The reference gas seal chamber is formed to be communicated each other with the measuring gas chamber, and a movable partitioning wall formed using a diaphragm or the like is provided in a communication part to partition a reference gas seal chamber side from a measuring gas chamber side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to a heat conduction type gas analyzer.

  In general, heat conduction type gas analyzers include a type in which a reference gas is sealed in a reference gas chamber and a type in which a reference gas is circulated.

  In the heat conduction type gas analyzer of the type in which the reference gas is sealed in such a reference gas chamber, conventionally, a reference gas sealing chamber, a measurement gas chamber, a hot wire element installed in the reference gas chamber, It is configured to include a hot wire element installed in the measurement gas chamber and a resistance bridge circuit formed by incorporating the hot wire element so as to generate an unbalanced current or voltage (for example, non-patent document). 1).

  In such a conventional heat conduction type gas analyzer, the reference gas sealing chamber is sealed from the outside so that the reference gas can be sealed inside, while the measurement gas chamber is sealed from the outside. Instead, the measurement gas is always circulated and measured.

  In this case, the heat conduction type gas analyzer is conventionally formed by completely separating the reference gas sealing chamber and the measurement gas chamber.

  Since the reference gas enclosure is sealed from the external environment, the density of the enclosed reference gas is constant and does not change regardless of changes in temperature and pressure in the external environment. The value was always constant.

  On the other hand, since the measurement gas chamber is configured to circulate the measurement gas without being sealed from the outside as described above, the measurement gas is affected by the external environment such as temperature and pressure. . Therefore, since the temperature and pressure of the measurement gas in the measurement gas chamber change, these changes appear as density changes.

  In this case, since the reference gas sealing chamber is sealed and not affected by the external environment, the internal environment of the reference gas sealing chamber and the measurement gas chamber are not the same, and differences in temperature and pressure occur, resulting in measurement conditions. Therefore, there is a problem that accurate measurement values cannot be obtained.

  In order to solve such a problem, it is possible to correct by using a CPU or the like in order to eliminate an error in the measurement value, but if the correction device is provided, the equipment cost increases. was there.

Shotaro Oka, “Industrial Gas Analysis (Principle and Application of Continuous Analyzer)”, Kyoritsu Publishing Co., Ltd., November 1, 1966, P147-P164

  The present invention can automatically adjust the internal environment of the reference gas sealing chamber and the measurement gas chamber to be the same, and does not require the use of an expensive correction device using a CPU or the like, so that accurate measurement is possible. It is an object of the present invention to provide a heat conduction type gas analyzer capable of obtaining a value.

  In order to solve the above problems, a heat conduction type gas analyzer according to the present invention as claimed in claim 1 includes a reference gas sealing chamber in which a reference gas is sealed, and a measurement gas chamber in which the measurement gas is circulated. A hot wire element installed in the reference gas chamber, a hot wire element installed in the measurement gas chamber, and a resistance bridge circuit formed using the hot wire element, the heat of the reference gas and the measurement gas In a heat conduction type gas analyzer configured to analyze a composition of a measurement gas by measuring an unbalanced current or voltage generated in the resistance bridge circuit due to a resistance change of the heat ray element based on a difference in conductivity, The internal environment of the reference gas sealing chamber is formed so as to correspond to the internal environment of the measurement gas chamber.

  That is, a heat conduction type gas analyzer according to the present invention as set forth in claim 1 includes a reference gas sealing chamber in which a reference gas is sealed, a measurement gas chamber in which the measurement gas is circulated, and the reference gas chamber. A hot wire element installed in the measurement gas chamber, a resistance bridge circuit formed using the hot wire element, and based on a difference in thermal conductivity between the reference gas and the measurement gas An improved heat conduction gas analyzer configured to analyze the composition of a measurement gas by measuring an unbalanced current or voltage generated in the resistance bridge circuit due to a resistance change of the heat ray element, The difference from the conventional heat conduction type gas analyzer is that the internal environment of the reference gas sealing chamber is formed so as to correspond to the internal environment of the measurement gas chamber.

  According to a second aspect of the present invention, there is provided the heat conduction type gas analyzer according to the present invention, wherein the reference gas sealing chamber is formed so that the volume thereof is variable, and the internal environment of the measurement gas chamber is changed by the volume change. It is formed so as to be able to match the internal environment.

  That is, in the heat conduction type gas analyzer according to the second aspect of the present invention, the volume of the reference gas sealing chamber is not constant, and the temperature and pressure of the internal environment are changed by changing the volume. It is configured to match the internal environment of the measurement gas chamber.

  According to a third aspect of the present invention, there is provided the heat conduction type gas analyzer according to the present invention, wherein the reference gas sealing chamber and the measurement gas chamber are formed so as to communicate with each other, and the reference gas sealing chamber side is formed in the communicating portion. A movable partition wall that partitions the measurement gas chamber side is provided.

  That is, in the heat conduction type gas analyzer according to the third aspect of the present invention, the reference gas sealing chamber and the measurement gas chamber are not formed separately from each other, but the reference gas sealing The chamber and the measurement gas chamber are formed so as to communicate with each other via the movable partition wall, and the volume of the reference gas sealed chamber is determined by pressure deformation of the movable partition wall due to the pressure fluctuation of the gas in the measurement gas chamber. Is formed to change.

  According to a fourth aspect of the present invention, there is provided the heat conduction gas analyzer according to the present invention, wherein the movable partition wall can be automatically displaced so that the pressures in the measurement gas chamber and the reference gas sealed chamber are in an equilibrium state. It is characterized by being formed.

  That is, in the heat conduction type gas analyzer according to the present invention as set forth in claim 4, the movable partition wall automatically responds to the pressure change in the measurement gas chamber without any operation or control. By displacing, the pressure in the measurement gas chamber and the reference gas sealed chamber is brought into an equilibrium state.

  According to a fifth aspect of the present invention, there is provided the heat conduction type gas analyzer, wherein the movable partition is formed by using a mechanical displacement mechanism.

  That is, in the heat conduction type gas analyzer according to the present invention described in claim 5, when the internal environment in the measurement gas chamber changes, the movable partition wall is mechanically displaced, whereby the measurement gas is measured. The pressure in the chamber and the reference gas sealed chamber is balanced.

  According to a sixth aspect of the present invention, there is provided the heat conduction type gas analyzer, wherein the mechanical displacement mechanism is formed using a diaphragm.

  That is, in the heat conduction type gas analyzer according to the sixth aspect of the present invention, the movable partition is formed by a diaphragm.

  According to a seventh aspect of the present invention, there is provided the heat conduction type gas analyzer, wherein the mechanical displacement mechanism is formed using a piston.

  That is, in the heat conduction type gas analyzer according to the seventh aspect of the present invention, the movable partition wall is formed by a piston.

  In the heat conduction type gas analyzer according to the present invention described in claim 8, the mechanical displacement mechanism is formed using a bellows.

  That is, in the heat conduction type gas analyzer according to the eighth aspect of the present invention, the movable partition wall is formed of a bellows.

  A heat conduction type gas analyzer according to the present invention as set forth in claim 1 is installed in a reference gas sealing chamber in which a reference gas is sealed, a measurement gas chamber in which the measurement gas is circulated, and the reference gas chamber. A heat bridge element formed in the measurement gas chamber, and a resistance bridge circuit formed using the heat line element, and the heat ray based on a difference in thermal conductivity between the reference gas and the measurement gas. In a heat conduction type gas analyzer configured to analyze a composition of a measurement gas by measuring an unbalanced current or voltage generated in the resistance bridge circuit due to a resistance change of an element, an internal environment of the reference gas sealing chamber Is formed so as to correspond to the internal environment of the measurement gas chamber, so that the internal environment of the reference gas sealing chamber and the measurement gas chamber, that is, the temperature and pressure are the same, and the unbalanced electric energy or voltage The It can be constant. As a result, the stability and accuracy of measurement can be improved to obtain an accurate measurement value, and it is not necessary to use an expensive correction device using a CPU or the like, thereby reducing the equipment cost.

  According to a second aspect of the present invention, there is provided the heat conduction type gas analyzer according to the present invention, wherein the reference gas sealing chamber is formed so that the volume thereof is variable, and the internal environment of the measurement gas chamber is changed by the volume change. Since it is formed so as to match the internal environment, the internal environment of the reference gas sealing chamber and the measurement gas chamber can be easily equalized by changing the volume of the reference gas sealing chamber. Thereby, for example, in order to equalize the pressure, a correction device that pressurizes or depressurizes the reference gas sealed chamber is unnecessary, and a situation in which the equipment cost increases can be avoided.

  According to a third aspect of the present invention, there is provided the heat conduction type gas analyzer according to the present invention, wherein the reference gas sealing chamber and the measurement gas chamber are formed so as to communicate with each other, and the reference gas sealing chamber side is formed in the communicating portion. Since the movable partition wall separating the measurement gas chamber side is provided, it is possible to easily change the volume of the reference gas sealing chamber only by displacing only the movable partition wall in the communication portion. Therefore, the structure of the reference gas sealing chamber can be prevented from becoming complicated, and the manufacturing cost of the reference gas sealing chamber can be kept low.

  According to a fourth aspect of the present invention, there is provided the heat conduction gas analyzer according to the present invention, wherein the movable partition wall can be automatically displaced so that the pressures in the measurement gas chamber and the reference gas sealed chamber are in an equilibrium state. Therefore, an apparatus or operation for displacing the movable partition is not required. Therefore, the equipment cost can be reduced while avoiding the complexity of the equipment.

  Further, in the heat conduction type gas analyzer according to the present invention described in claim 5, since the movable partition is formed using a mechanical displacement mechanism, the structure is not complicated, and a commercially available part is used. Since it can manufacture, manufacturing cost can be reduced.

  Further, in the heat conduction type gas analyzer according to the present invention described in claim 6, since the mechanical displacement mechanism is formed by using a diaphragm, the structure is not complicated and the manufacturing cost can be reduced. it can.

  Further, in the heat conduction type gas analyzer according to the seventh aspect of the present invention, since the mechanical displacement mechanism is formed using a piston, the structure is not complicated and the manufacturing cost can be reduced. it can.

  Further, in the heat conduction type gas analyzer according to the present invention described in claim 8, since the mechanical displacement mechanism is formed using a bellows, the structure is not complicated and the manufacturing cost can be reduced. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the heat conduction type gas analyzer 11 according to the present embodiment includes a reference gas sealing chamber 12 in which a reference gas is sealed and a measurement gas chamber accommodated in a state in which the measurement gas flows. 13, a hot wire element 14 installed in the reference gas chamber 12, a hot wire element 15 installed in the measurement gas chamber 13, and a resistance bridge circuit 16 formed using the hot wire elements 14, 15. And measuring the composition of the measurement gas by measuring the unbalanced current or voltage generated in the resistance bridge circuit 16 due to the resistance change of the hot wire elements 14 and 15 based on the difference in thermal conductivity between the reference gas and the measurement gas. In the heat conduction type gas analyzer 11 configured to analyze, the internal environment of the reference gas sealing chamber 12 can be adapted to the internal environment of the measurement gas chamber 13.
As shown in FIG. 1, the reference gas sealing chamber 12 is formed such that its volume is variable, and the internal environment can be matched with the internal environment of the measurement gas chamber 13 by the volume change. Is formed.
As shown in FIG. 1, the reference gas sealing chamber 12 and the measurement gas chamber 13 are formed so as to communicate with each other, and the reference gas sealing chamber 12 side and the measurement gas chamber 13 side are connected to the communication portion 17. A movable partition wall 18 is provided for partitioning.
As shown in FIG. 1, the movable partition wall 18 is formed so that it can be automatically displaced so that the pressures in the measurement gas chamber 13 and the reference gas sealing chamber 12 are in an equilibrium state. .
The movable partition 18 is formed using a mechanical displacement mechanism as shown in FIG.
The mechanical displacement mechanism is formed using a diaphragm 19 as shown in FIG.
An embodiment using a piston as the mechanical displacement mechanism and an embodiment using a bellows as the mechanical displacement mechanism are also possible.

Examples of the present invention will be described below.
As shown in FIG. 1, the heat conduction type gas analyzer 11 according to the present embodiment includes a reference gas sealing chamber 12 in which a reference gas is sealed and a measurement gas chamber 13 in which the measurement gas is circulated. Have.

As shown in FIG. 1, the reference gas sealing chamber 12 is sealed so that gas does not flow in from the outside or gas does not flow out to the outside, and the reference gas is sealed in the inside thereof.
Therefore, the composition of the reference gas is constant and does not change.
In this embodiment, air is used as the reference gas, but argon, nitrogen, or the like can also be used.

On the other hand, as shown in FIG. 1, the measurement gas chamber 13 is not sealed, and a gas introduction port 20 through which the measurement gas flows from the outside and a gas discharge port 21 through which the measurement gas flows out are opened. Yes.
There are three types of measurement gas chambers, diffusion type, convection type, and flow type, depending on how the measurement gas is introduced. The diffusion type represented by the casa-meter is conventionally used, and the measurement gas is filled with glass wool. The convection type is configured so that the measurement gas flowing in from the gas inlet is naturally convected and flows out from the gas outlet when heated by the hot wire element. The flow type is configured to flow the measurement gas from below to above. The measurement gas chamber 13 according to the present embodiment employs the convection type.

  In addition, the measurement gas in the present embodiment is intended for hydrogen included with nitrogen, air, and argon, or helium included with nitrogen, air, and argon.

As shown in FIG. 1, a hot wire element 14 is installed in the reference gas chamber 12.
Similarly, as shown in FIG. 1, a hot wire element 15 is also installed in the measurement gas chamber 13. These heat ray elements 14 and 15 are formed in a coil shape.

  The hot wire element 14 installed in the reference gas chamber 12 and the hot wire element 15 installed in the measurement gas chamber 13 exhibit the same resistance value under the same environment.

  As shown in FIG. 2, a resistance bridge circuit 16 is configured using the hot wire element 14 installed in the reference gas chamber 12 and the hot wire element 15 installed in the measurement gas chamber 13. Yes.

Platinum is used as a material for the heat ray elements 14 and 15.
In addition to platinum, metals such as gold, nickel and tungsten can be used as the material for the heat ray elements 14 and 15.
Further, since a metal such as platinum may cause a chemical reaction with the measurement gas, it is coated with a glass or silicon thin film to prevent this.
It is also possible to use a thermistor or the like as the detection element instead of the metal resistance wire.

As shown in FIG. 2, the resistance bridge circuit 16 further includes two resistance elements 22 and 23 in addition to the heat ray element 14. The resistance elements 22 and 23 are in the same environment. Then, it forms so that the same resistance value as said heat ray element 14 and 15 may be shown.

The resistance bridge circuit 16 measures the resistance change of the heat ray elements 14 and 15.
In this case, the measurement method includes direct measurement of the unbalanced current or voltage of the bridge circuit, and an unbalanced signal is supplied to the servo amplifier, and the sliding resistance is automatically adjusted to automatically balance the bridge circuit. The resistive bridge circuit 16 according to the present embodiment employs a method of directly measuring the former unbalanced current or unbalanced voltage.

The resistance bridge circuit has three types of coupling methods of series type, parallel type and cross type depending on the arrangement of the reference gas chamber 12 and the measurement gas chamber 13 with respect to the power source. The circuit 16 employs a parallel type as shown in FIG.
Of course, a series type or a cross type can be adopted as the resistance bridge circuit.

The reference gas sealing chamber 12 is formed so as to communicate with the measurement gas chamber 13 as shown in FIG.
That is, a communication portion in which a pipe 24 protruding from the reference gas sealing chamber and a pipe 25 protruding from the measuring gas chamber 13 are connected between the reference gas sealing chamber 12 and the measurement gas chamber 13. 17 is arranged.

  As shown in FIG. 1, the communication portion 17 is provided with a movable partition wall 18 that partitions the reference gas sealing chamber 12 side and the measurement gas chamber 13 side.

  The movable partition wall 18 is formed using a diaphragm 19 as shown in FIG. The movable partition wall 18 can be formed using a piston or a bellows although not shown.

  As shown in FIG. 1, the reference gas sealing chamber 12 is configured to include a part of the communication portion 17 partitioned by the conduit 24 and the movable partition wall 18. No. 12 is formed so that the volume thereof is changed by the pressure deformation of the diaphragm 19.

  That is, when the internal environment such as the temperature and pressure of the measurement gas chamber 13 changes, the diaphragm 19 is adjusted so that the pressures in the measurement gas chamber 13 and the reference gas sealing chamber 12 are balanced. The pressure is automatically deformed, and the volume of the reference gas sealing chamber 12 changes. As a result, the internal environments of the measurement gas chamber 13 and the reference gas sealing chamber 12 are matched.

  In addition, although the illustration is abbreviate | omitted so that the said reference gas enclosure chamber 12 may become the same temperature as the said measurement gas chamber 13, it is provided in one apparatus.

The heat conduction type gas analyzer 11 has a required power supply of 110 V (AC) and an output signal of 4
-20 mA (0-20 mA), required gas flow rate 10-500 cc / min, allowable ambient temperature is normal air temperature, and measurement accuracy is ± 1%.

Hereinafter, the operation of this embodiment will be described.
In the heat conduction type gas analyzer 11 according to the present embodiment, when a constant current is supplied to the heat ray elements 14 and 15 to generate heat, the surrounding gas components are constant and there is no significant fluctuation. As long as the heat of the hot wire elements 14 and 15 escapes to the outside through heat conduction in the surrounding gas.
Immediately after starting to energize the heat ray elements 14 and 15, the temperature of the heat ray elements 14 and 15 gradually increases, but eventually, the amount of heat generated by the current and the amount of heat to escape reach an equilibrium state, and the heat ray elements 14 and 15 The temperature becomes constant.
The amount of heat that escapes depends on the thermal conductivity of the surrounding gas, and increases in the case of a gas having a high thermal conductivity, so that the temperature drop also increases. On the other hand, in the case of a gas having a low thermal conductivity, the amount of heat that escapes is small, so the temperature drop is also small.
The resistance values of the heat ray elements 14 and 15 vary depending on the temperature.
Therefore, if the change in resistance of the hot wire elements 14 and 15 that has reached a thermal equilibrium state is measured under a certain condition, the change in temperature of the hot wire elements 14 and 15 can be measured.
And if the temperature change of the said hot wire elements 14 and 15 can be known, the change of the thermal conductivity of the gas which exists around the said hot wire elements 14 and 15 can be known.
Since the thermal conductivity of the mixed gas changes depending on the gas mixing ratio, if the relationship between the gas mixing ratio and the thermal conductivity is obtained in advance, the change in the thermal conductivity is measured and the analysis of the gas component ratio is performed. It becomes possible.
In order to utilize such a principle, the heat conduction type gas analyzer 11 according to the present invention forms the resistance bridge circuit 16 as described above and performs gas analysis by performing comparative measurement.

When a constant current is passed through the resistance bridge circuit 16 shown in FIG. 2, the resistance value of the hot wire element 14 installed in the reference gas sealing chamber 12 and the resistance value of the hot wire element 15 installed in the measurement gas chamber 13. Since the values are different, an unbalanced current flows between the detection terminals A and B in the resistance bridge circuit 16 shown in FIG.
Therefore, the composition of the measurement gas can be analyzed by measuring this unbalanced current or unbalanced voltage and comparing it with a measured value of a known mixed gas measured in advance.

  When the measurement is performed, the gas flowing through the measurement gas chamber is affected by the outside air temperature and the external atmospheric pressure, so that the temperature and pressure of the gas are appropriately changed. If the internal environment of the measurement gas chamber is different, the zero point may not be stable, the measurement value may not be stable, and the accuracy may be reduced. However, the heat conduction type gas analyzer 11 according to the present embodiment may be used. In this case, the reference gas sealing chamber 12 and the measurement gas chamber 13 are communicated with each other, and the movable partition 18 is provided in the communication portion 17, so that the temperature and pressure of the measurement gas chamber 13 are provided. Since the movable partition wall 18 is displaced or deformed in accordance with the environmental change such as the internal environment of the reference gas chamber 12 according to the change in the internal environment of the measurement gas chamber 13, the zero point or Obtained stability of measured values Rutotomoni measurement accuracy can be improved.

  The present invention includes a reference gas sealing chamber in which a reference gas is sealed, a measurement gas chamber that is stored in a state in which the measurement gas flows, a hot wire element that is installed in the reference gas chamber, and a measurement gas chamber that is installed in the measurement gas chamber. And a resistance bridge circuit formed using the hot wire element, and a resistance bridge circuit formed by resistance change of the hot wire element based on a difference in thermal conductivity between the reference gas and the measurement gas. The present invention is applicable to a heat conduction type gas analyzer configured to analyze a composition of a measurement gas by measuring an equilibrium current or voltage.

It is a conceptual diagram which shows the structure of the detection part in the heat conductive gas analyzer which concerns on the Example of this invention. It is a conceptual diagram of the resistance bridge circuit in the heat conduction type gas analyzer which concerns on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Heat conduction type gas analyzer 12 Reference gas enclosure 13 Measurement gas chamber 14 Heat wire element 15 Heat wire element 16 Resistance bridge circuit 17 Communication part 18 Movable partition 19 Diaphragm 20 Gas inlet 21 Gas exhaust 22 Resistance element 23 Resistance element 24 Tube Route 25 pipeline

Claims (8)

  A reference gas sealing chamber in which a reference gas is sealed; a measurement gas chamber that is stored in a state in which the measurement gas flows; a hot wire element installed in the reference gas chamber; and a hot wire element installed in the measurement gas chamber; An unbalanced current or voltage generated in the resistive bridge circuit due to a resistance change of the hot wire element based on a difference in thermal conductivity between the reference gas and the measurement gas. In the heat conduction type gas analyzer configured to analyze the composition of the measurement gas by measuring the internal gas, the internal environment of the reference gas sealed chamber is formed so as to correspond to the internal environment of the measurement gas chamber A heat conduction type gas analyzer characterized by that.   2. The reference gas sealing chamber is formed so that the volume thereof is variable, and the internal environment can be matched with the internal environment of the measurement gas chamber by changing the volume. The heat conduction type gas analyzer as described.   The reference gas sealing chamber and the measurement gas chamber are formed so as to communicate with each other, and a movable partition wall that partitions the reference gas sealing chamber side and the measurement gas chamber side is provided at the communication portion. Item 3. The heat conduction type gas analyzer according to Item 2.   4. The heat conduction type gas analysis according to claim 3, wherein the movable partition wall is formed so as to be automatically displaceable so that pressures in the measurement gas chamber and the reference gas sealed chamber are in an equilibrium state. vessel.   5. The heat conduction type gas analyzer according to claim 4, wherein the movable partition wall is formed using a mechanical displacement mechanism.   6. The heat conduction type gas analyzer according to claim 5, wherein the mechanical displacement mechanism is formed by using a diaphragm.   6. The heat conduction type gas analyzer according to claim 5, wherein the mechanical displacement mechanism is formed using a piston. 6. The heat conduction type gas analyzer according to claim 5, wherein the mechanical displacement mechanism is formed using a bellows.

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