JPS604125Y2 - oxygen concentration detector - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an oxygen concentration detector that detects the oxygen concentration in exhaust gas by using a solid electrolyte made of zirconia, doria, etc. and utilizing the principle of an oxygen concentration battery.

Conventionally, electrodes such as platinum were provided on the inner and outer surfaces of a solid electrolyte tube made of zirconia, doria, etc., and the solid electrolyte tube was placed in an electric furnace, and the outer electrode was connected to a reference gas, such as air, flowing in the electric furnace, and the inner electrode was connected to the inner surface of the tube. Oxygen concentration detectors are often used that measure the oxygen concentration in the gas to be measured by bringing the oxygen concentration into contact with the gas to be measured using the principle of an oxygen concentration cell.

Among these oxygen concentration detectors, relatively small ones are generally housed in a storage case for convenient portability.

When the oxygen concentration detector is housed in such a storage case, it is necessary to prevent the temperature inside the storage case from rising due to the heating of the electric furnace, and to facilitate the circulation of air as a reference gas. The case is usually equipped with a ventilation fan.

However, in such an oxygen concentration detector that has a storage case equipped with a ventilation fan, the flow of the reference gas flowing through the electric furnace is not uniform and may cause turbulence, which may cause the temperature of the electric furnace to change. Fluctuations are often seen.

That is, temperature fluctuations in the reference gas affect the values obtained from the solid electrolyte.

For example, 02501) pITI, when the electric furnace temperature is 850°C, if this temperature is slightly lowered by 0.5°C, o, o
The electromotive force becomes lower by hv.

Therefore, for example, if the oxygen concentration is in the range of 50 ppm to 60 ppm, 0. When trying to measure with lppm accuracy,
The permissible variation value of the electromotive force mentioned above must be 0.94 mV or less.

Therefore, with a temperature change of 0.5°C, that is, the degree of influence o, ohv on the electromotive force value, it is naturally 0.5°C. lppm
There was a problem in that it was not possible to measure oxygen concentration with an accuracy of .

In addition, if the air contains flammable dust and it enters the electric furnace, it will naturally burn and consume oxygen, so the oxygen concentration in the air as a reference gas will fluctuate.
As shown in Figure A, there are problems such as large fluctuations in electromotive force, which affects measurement accuracy.In particular, small oxygen concentration detectors that are housed in a storage case and equipped with a ventilation fan are It is important to minimize temperature fluctuations and to avoid contamination with flammable dust.

The oxygen concentration detector of the present invention was developed to solve these conventional drawbacks, and has extremely low temperature fluctuations in the reference gas and contamination of flammable dust.
Electrodes are provided on the inner and outer surfaces of the solid electrolyte, and it is placed in an electric furnace, and the outer electrode is connected to a reference gas flowing in the electric furnace.
In an oxygen concentration detector that measures the oxygen concentration in a gas to be measured using the principle of an oxygen concentration battery by bringing each inner electrode into contact with the gas to be measured, an electric furnace for the reference gas that is in contact with the outer electrode of the solid electrolyte is used. This is an oxygen concentration detector that has a rectifying layer in the inward flow path.

The detailed structure of the present invention will be explained with reference to FIG. 1 showing a specific example. An inner electrode 2 and an outer electrode 3 are provided corresponding to the inner and outer surfaces of a solid electrolyte made of zirconia, thoria, etc. The oxygen detection element 1 is installed in an electric furnace 4.

The electric furnace 4 includes a heater 5 and the like, and is maintained at a constant temperature by an external temperature control circuit (not shown).

A rectifying layer 7 is provided in the flow path 6 of the electric furnace 4 through which a reference gas such as air flows into the electric furnace 4 .

The rectifying layer 7 is preferably formed of rock wool such as alumina fiber or silica fiber or fire-resistant porous porcelain, and has an aperture ratio of about 30 to 60% and a maximum aperture diameter of about 5 μ to 500 μ. Best.

Furthermore, one end of the oxygen detection element 1 is connected to a flow meter 8 and a gas inlet conduit 9, and the other end is connected to a gas outlet conduit 10.

All of these items are stored together in a storage case 11 for convenient portability.

The storage case 11 includes a ventilation fan 12 for preventing a temperature rise inside the storage case 11 and a reference gas inflow hole 1.
3 is provided.

The oxygen concentration detector of the present invention has the above-described configuration, and in particular, a reference gas such as air in contact with the outer electrode 3 of the oxygen detection element 1 made of a solid electrolyte is connected to a rectifier provided in the flow path 6. Since the reference gas flows into the electric furnace 4 through the layer 7, there is almost no turbulence in the flow of the reference gas, and the flow rate etc. are also adjusted to be almost constant.

Therefore, since the reference gas flows in a substantially constant state, there is almost no temperature fluctuation.

In addition, since the rectifying layer also has the effect of a filter, it can prevent combustible dust contained in the air from flowing into the electric furnace 4, and it can prevent fluctuations in electromotive force due to dust combustion. It is.

Next, a specific example using the oxygen concentration detector of the present invention will be explained with reference to FIG.

FIG. 3 shows concentration fluctuations when a gas to be measured with an oxygen concentration of 50 ppm was continuously measured by flowing it through the oxygen concentration detector of the present invention.

As is clear from comparing this with the measurement results using the conventional oxygen concentration detector shown in FIG. 2 above, the detector of the present invention has less measurement variation.

As is clear from the above explanation, the oxygen concentration detector of the present invention prevents the influence of temperature fluctuations caused by turbulent flow of air as a reference gas, the influence of combustion of dust in the air, etc., and generates an electromotive force as described above. As a result, it is an oxygen concentration detector that can detect even minute changes in oxygen concentration, making it especially portable and ideal for detecting oxygen concentration in gases where fluctuations in oxygen concentration are relatively small. This is a small-sized oxygen concentration detector that is extremely useful industrially.

[Brief explanation of drawings]

Fig. 1 is a schematic illustration of a specific example of the oxygen concentration detector of the present invention, Fig. 2 is a specific illustration of measurement results by a conventional oxygen concentration detector, and Fig. 3 is an illustration of the oxygen concentration of the present invention. FIG. 3 is a specific explanatory diagram of measurement results by a detector. 1...Oxygen detection element, 2...Inner surface electrode, 3...Outer surface electrode, 4...Electric furnace, 5
...Heater, 6...Flow path, 7...
... Rectifying layer, Flow meter, 9...
Gas inlet conduit, 10...Gas outlet conduit, 11.
... Storage case, 12 ... Ventilation fan, 13
...Inflow hole.

Claims (1)

[Scope of utility model registration request] Electrodes are provided on the inner and outer surfaces of the solid electrolyte, and it is placed in an electric furnace, and the outer electrode is connected to a reference gas flowing in the electric furnace.
In an oxygen concentration detector that measures the oxygen concentration of the gas to be measured by bringing the inner electrode into contact with the gas to be measured using the principle of an oxygen concentration battery, the reference gas in the electric furnace is in contact with the outer electrode of the solid electrolyte. An oxygen concentration detector characterized in that a rectifying layer is provided in the flow path to the oxygen concentration sensor.