JPS60243558A - Analyzing device of oxygen gas concentration - Google Patents

Abstract

PURPOSE:To attempt lower cost and higher precision, by fixing hermetically a perforated cover to a large surface provided with the reference electrode of solid electrolytic property formed principally in a flat plate. CONSTITUTION:In an O2 gas concentration analysis device 20 on the polarographical measuring principle, on one principal surface 38 of a solid electrolytic property formed principally in a flat plate is fixed with a measuring electrode 30 exposed to the gas specimen provided with an electron transmitting body and on the other principal surface 33 the reference electrode 31 contacting with the gas specimen through a hole 37 limiting gas dispersion is fixed respectively. These electrodes 30 and 31 are connected with a joint of a material 32 of electrolytic property. The principal surface 33 on the side of the electrode 31 is covered with a cover 35 perforated with a hole 37 for limiting gas dispersion. By this arrangement, an O2 gas concentration analysis device suited to a low cost mass production and capable in practice of measurement of O2 concentration in a high precision.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to an oxygen gas concentration analyzer.

[Background f of the Invention] Conventionally, zirconia oxygen concentration cells have been mainly used to measure oxygen concentration in gas. This concentration cell is made by forming electrode surfaces of platinum or other material on both sides of a zirconia plate, which is a solid electrolyte.When measuring oxygen concentration, one electrode is charged with the gas to be measured at a high temperature of 600 to 900 degrees Celsius. The oxygen concentration in the gas to be measured is measured by bringing the other electrode into contact with a reference gas containing oxygen of known concentration and measuring the electromotive force generated between the two electrodes. However, since this measuring device attempts to utilize the electromotive force determined by the oxygen partial pressure X and temperature of two oxygen systems (oxygen in the measured gas and oxygen in the reference gas), the If the oxygen partial pressure is close to the oxygen partial pressure in the reference gas, only a small electromotive force can be obtained, making measurement difficult and requiring a reference gas, which complicates the apparatus.

In addition to oxygen gas concentration analyzers based on such a potentiometric measurement principle, oxygen gas concentration analyzers based on a polarographic measurement principle are known. This measuring device is
It is equipped with a detection section consisting of a box having an oxygen ion permeable body and a diffusion hole, and both measurement and reference electrodes formed on both sides of the oxygen ion permeable body.
The gas is kept at a high temperature of 0° C. and placed in the gas to be measured, and the voltage applied between the reference and measurement electrodes is gradually increased. Initially, as the voltage increases, the current flowing between the electrodes also increases, but above a certain voltage, the current value is maintained at a constant value. This constant current value is a function of oxygen diffusing through the holes), and based on this, the oxygen concentration in the gas to be measured is measured by measuring the constant current value. According to this analyzer, since a voltage is applied between the electrodes and the current flowing between the two electrodes is used, it is easier to measure than the concentration battery that uses the electromotive force generated between the electrodes as described above. becomes easier. Furthermore, in this device, the fact that the oxygen concentration and the limiting current value are in a substantially proportional relationship makes measurement easy, and unlike concentration batteries, a reference gas is not required.

Conventionally, an oxygen gas analyzer that follows such a polarographic measurement principle, as shown in FIGS. A reference electrode 12 is formed in the shape of a shape, and a measurement electrode 13 is formed on the lower surface of the reference electrode 12 to face the reference electrode 12.
On the solid electrolyte 11 on the side, a cylindrical lid 14 with an inverted U-shaped cross section and a diffusion hole 15 for oxygen gas diffusion in the upper part is fixed so as to cover the reference electrode, thereby forming the box 10. As a heating means, a resistance heating wire such as nichrome wire or Kanthal wire is wound around the outer periphery of a ceramic tube in a male shape. For this reason, not only is the manufacturing method complicated and unsuitable for mass production, but it is also difficult to accurately control the temperature of the oxygen gas analyzer itself, making it impossible to measure oxygen concentration with high precision. was.

[Purpose of the invention]

An object of the present invention is to provide an oxygen gas concentration analyzer that can accurately measure oxygen concentration, is inexpensive, and is suitable for mass production.

[Summary of the invention]

That is, in the oxygen gas concentration analyzer of the present invention, a solid electrolyte capable of conducting oxygen ions is brought into contact with the gas to be measured through a measurement electrode that has electronic conductivity and is exposed to the gas to be measured, and a hole that restricts gas diffusion. A reference electrode is fixed to each
In an oxygen gas concentration analyzer in which the measuring electrode and the reference electrode are respectively connected to the connection part of the solid electrolyte through conductor paths, the measuring electrode and the other main A reference electrode is fixed to each surface, the main surface on the reference electrode side is covered with a lid body having holes for restricting the gas diffusion, and the lid body is equipped with a heating means. It is something.

The oxygen gas concentration analyzer of the present invention is suitable for mass production at a low cost, and has the great advantage of being able to accurately measure oxygen concentration in terms of use.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In this example, in an oxygen gas concentration analyzer 20 that operates according to the polarographic measurement principle, a measurement electrode that has an electron conductor on the whole surface 38 of a solid electrolyte 32 mainly composed of a flat plate and is exposed to a gas to be measured. 30, a reference electrode 31 is fixed to each of the other living surfaces 66, which contacts the gas to be measured through a hole 67 for restricting gas diffusion. The measuring electrode 0 and the reference electrode 31 are each connected to a connecting portion of the solid electrolyte 32 via a conductor path. The main surface 33 on the side of the reference electrode 61 is covered with a lid 35 having holes 37 for restricting the gas diffusion, and the lid 35 is equipped with heating means 39 .

This makes it possible to obtain an oxygen scum concentration analyzer that is suitable for mass production at a low price and that can accurately measure oxygen concentration in terms of use.

The reference electrode 31 is made of, for example, porous platinum or the like, and has a thickness of 5 to 50%.
A 10 μm thick film is then fixed to the main surface 33 by a known method such as printing. The lid body 35 is made of a gas-impermeable material such as ceramic such as zirconium oxide, and is fixed and integrated with the solid t% material 32 by sintering, for example, to form a closed space 36 with the reference electrode 31. There is.

The measurement electrode 60 is made of a film of porous platinum, for example, and is fixed to the main surface 38 by a known method such as a printing method. The surface of the measuring electrode 30 opposite the main surface 68 is preferably covered by a porous protective layer (not shown). This protective layer consists, for example, of magnesium spinel and serves as protection against the calorimetric gas.

The heating means 39 is a heating element made of a metal such as PI or P, -ah alloy, preferably has a meandering shape, and preferably has a thickness of 10 μm. Let me explain in detail.

As shown in FIG. 5(a) to (k), three sheets of 6 mol% Y,
Solid electrolyte green sheet such as 0-2rα (58X
am
A platinum paste is printed on one side and dried at 160°C for 10 minutes to form an unfired reference electrode 42, and a platinum paste is printed on the other side opposite to the reference electrode 42 as shown in FIG. Platinum paste was printed so that the platinum paste was arranged as shown in FIG.
As shown in (d), print the organic binder at 130°C
A space forming body 44 was formed by drying for 10 minutes and removing it again during sintering.

As shown in FIG. 5(f), alumina paste is printed on the other green sheet 51 and dried at 130° C. for 10 minutes to form an unfired insulating layer 52m. As shown in (g), a platinum paste was printed and dried at 130° C. for 10 minutes to form a meandering heater 56 in an unfired state. The alumina paste was printed on this as shown in FIG. 5(h) and dried at 130° C. for 10 minutes to form a heater layer covered with an insulating layer 52b in an unfired state on the green sheet.

Then these green seas) 41.51, 61
After stacking them and applying pressure bonding of 110Icβ at 100° C. for 10 minutes to form a laminated structure as shown in FIG. The whole was fired at 1 boooC for 1 hour. Furthermore, a porous protective layer is formed by plasma spraying magnesium spinel powder, and the oxygen gas concentration analyzer 70 is also formed.

If the oxygen gas concentration analyzer that operates according to the polarognographic measurement principle is constructed in this way, the detector 7
Since 0 can be directly heated, the analyzer can be heated with less electric power.

Next, the results of measuring gases to be measured having various oxygen concentrations using the above device will be shown. In this measurement, the gas to be measured was sent to the detector while controlling the electric power applied to the heater to maintain the temperature at 800°C. At this time, in the detector,
Detector 70 through diffusion hole 71 by diffusion of oxygen gas
Oxygen gas flows into the space 44 . The oxygen gas that has flowed in this way is transferred to the reference electrode 42. Due to the voltage applied to the measurement electrode 43 , it is reduced at the reference electrode 42 to become oxygen ions, moves through the solid electrolyte to the measurement electrode 43 , where it is oxidized to become oxygen gas, and is discharged to the outside of the detector 70 . . In this way, while supplying the gas to be measured, the reference electrode 42. changing the voltage applied between the measurement electrodes 430;
The current value at each voltage was measured. This measurement was carried out for each of the gases to be measured having different oxygen concentrations.As a result, the relationship (mA) between oxygen concentration (correlation) and limiting current characteristics as shown in FIG. 6 was obtained. In an oxygen gas concentration analyzer that utilizes this limiting current characteristic, the limiting current with respect to oxygen concentration changes significantly depending on the detected gas temperature at the time of measurement. However, with such a structure, since the detector and the heater are integrated, the temperature of the detector can be controlled with high precision, and measurement accuracy does not deteriorate due to the detected gas temperature.

As described above, the oxygen gas concentration analyzer of the present invention can easily form a closed space in contact with the reference electrode, so it is suitable for mass production, is inexpensive, and can be attached to a lid. Since the heater is provided, it is easy to control the temperature of the analyzer and highly accurate oxygen concentration analysis can be achieved, which is an extremely practical and important advantage.

It should be noted that, as a matter of course, the present invention is not limited to this example.

〔Effect of the invention〕

According to the invention, the solid electrolyte is mainly a flat plate)
By tightly fixing a lid having holes on a large surface having a reference electrode of the solid electrolyte to the solid electrolyte, the lid can be closed between the solid electrolyte plate provided with the reference electrode and the lid in an industrially advantageous method. It has the advantage that it can be manufactured by a manufacturing method that is suitable for mass production because it can form a space with a large space.

Since the heater is formed in the case and the lid, the heater and the oxygen gas concentration analyzer are integrated, and the temperature of the analyzer can be controlled with high precision, so the temperature of the gas to be measured can be adjusted from low to low. The oxygen concentration in the measurement gas can be detected with high accuracy no matter how the temperature changes. Moreover, the analyzer can be efficiently and uniformly heated with less electric power.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional oxygen gas concentration analyzer, showing a cross-sectional view of the sensor and a circuit diagram of the device, FIG. 2 is a perspective view of the sensor, with some parts missing, and FIG. 3 is an illustration of a conventional oxygen gas concentration analyzer according to the present invention. FIG. 4 is an exploded perspective view of the oxygen gas concentration analyzer shown in FIG. 3, and FIG. 5 is a diagram showing the manufacturing of the oxygen gas concentration analyzer according to an embodiment of the present invention. FIG. 6, which is an explanatory drawing showing the process, is a diagram showing the relationship between the oxygen concentration and the limiting current value in the example. 11 solid electrolyte, 12 reference electrode, 13 measurement electrode, 10 box, 15 diffusion hole, 20... oxygen gas concentration analyzer, 60 measurement electrode, 31... reference electrode, 32... solid electrolyte, 35... - Lid, 66... Space, 37... Gas diffusion hole, 39... Heating element, 40... Air insulation layer, 41, 51
, 61 - Solid electrolyte green sheet, 42 - Reference electrode, 43 - Measurement electrode, 44 - Cavity forming body, 52 Insulating layer, 56 Meandering heater, 7 Gas diffusion hole. Tsumugi 1 Prisoner Taku 21 /4

Claims (1)

[Claims] A measurement electrode that has electron conductivity and is exposed to the gas to be measured and a reference electrode that contacts the gas to be measured through holes that limit gas diffusion are fixed to a solid electrolyte that can conduct oxygen ions, and these measurement electrodes and In an oxygen gas concentration analyzer in which reference electrodes are each connected to a solid electrolyte connection (ζ) via a conductor path, a measurement electrode is placed on one main surface of the solid electrolyte, which is mainly composed of a flat plate, and a measurement electrode is placed on the other main surface. Oxygen gas, characterized in that the reference electrodes are fixed to each other, the main surface on the reference electrode side is covered with a lid body having holes for restricting the gas diffusion, and the lid body is equipped with heating means. Concentration analyzer.