JPH0584853U - Zirconia gas analyzer - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a zirconia gas analyzer which prevents the internal electrode from being cooled during calibration and has no error between calibration and measurement. [Structure] In a zirconia gas analyzer for determining the concentration in a measurement gas from an electromotive force of a zirconia sensor composed of a zirconia solid electrolyte composed of an oxygen ion conductor, a tube inserted into a zirconia tube 1 constituting the zirconia sensor. Body 20 and gas introduction pipe 7 for introducing a calibration gas into the space formed by the outer circumference of this tube and the inner circumference of the zirconia tube
The calibration gas is introduced into the space between the zirconia tube 1 and the tube body 20 on the measurement gas inlet side of the zirconia tube 1, and the internal electrode 1 is arranged at the bottom of the zirconia tube.
It is configured to be discharged into the measurement gas by hitting 6a, and a gas flow velocity delay means is provided in the space.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

The present invention relates to a zirconia gas analyzer for measuring the concentration of O ₂ gas, and relates to a zirconia gas analyzer which prevents a measurement error caused by a temperature difference between calibration time and measurement time.

[0002]

[Prior Art]

 FIG. 2 is a sectional view showing a general structure of a zirconia gas analyzer and a calibration means. In the figure, 1 is a test tube type zirconia tube composed of a zirconia solid electrolyte made of an oxygen ion conductor, 2 is a ring-shaped positive side contact to be connected to an electrode lead of an external electrode 16b described later, and 3 is an internal section described later. A ring-shaped negative contact connected to the electrode lead of the electrode 16a, 4 is a cover plate, 5 is an O-ring, 6 is a probe pipe, and 7 and 7'are non-catalytic quartz tubes or other glass tubes. Introducing pipe, 8 is a comparative gas introducing pipe, 9 is a thermocouple, 10 is a heater for heating the zirconia pipe 1, 11 is a partition plate, 12 is a wall of a flue through which the measurement gas MG such as combustion exhaust gas flows. A flange for fixing the device to a device (not shown), 13 is a terminal box, 14 is a packing, 15 is a calibration gas inlet, and 16a is a multi-porous platinum attached to the bottom of the zirconia tube 1. Internal electrodes that, 16b is an outer electrode made of a loaded porous platinum on the surface (outer surface) of the zirconia tube 1 is in contact with a reference gas RG.

In the zirconia gas analyzer having the above structure, MG is guided inside the zirconia tube 1 and supplied to the inner electrode 16a. Further, the comparative gas RG introduced from the comparative gas introduction pipe 8 is supplied to the outside of the zirconia pipe. In such a state, when the zirconia tube 1 is heated by the heater 10 to a temperature at which it becomes an oxygen ion dielectric (usually about 750 ° C.), the measurement gas MG comes into contact with the internal electrode 16a and has an oxygen concentration Causes battery action. As a result, different electromotive force is generated between the outer electrode 16b of the zirconia sensor and the negative contact 3 depending on the oxygen partial pressure. The oxygen concentration in the measured gas can be measured by processing the detection signal corresponding to this electromotive force with a signal processor (not shown).

[0004]

[Problems to be solved by the device]

 By the way, in the above-mentioned conventional example, the calibration gas is directly blown into the zirconia pipe 1 through the calibration gas inlet 15 and the calibration gas inlet pipes 7 and 7'during calibration, so that the measurement gas and the calibration gas in the sensor can be reliably discharged. Can be replaced. However, since the calibration gas directly hits the inner electrode, the inner electrode 16a is cooled. Therefore, there is a problem that a measurement error occurs because the electrode temperature is different from that at the time of measurement. Further, when drain-in is mixed in the measurement gas line, its drain is directly blown onto the electrode, so that the electrode 16a is rapidly cooled and damaged. There was a problem such as. FIG. 3 is a sectional view of an essential part showing an improved example of FIG.

In FIG. 3, the same parts as those in FIG. 2 are denoted by the same reference numerals and the duplicated description is omitted, but 17 is a filter attached to the tip of the probe pipe, for example, silicone which is a non-catalytic member. It is composed of a sintered material of carbide. The filter 17 also functions as a protector for dust contained in the measurement gas.

In this case, the calibration gas is discharged into the filter 17, diffuses into the zirconia tube 1 and reaches the internal electrode. In this conventional example, since the calibration gas does not directly face the internal electrode, the calibration gas does not cool the internal electrode 16a, and the error during measurement can be reduced.

However, in this case, a large amount of calibration gas is required, the gas in the zirconia tube 1 is difficult to be replaced, and the measurement gas is difficult to be taken into the zirconia tube 1. The present invention was made in order to solve the above-mentioned problems of the prior art. The calibration gas is sufficiently heated and then guided to the internal electrodes to prevent cooling of the internal electrodes during the calibration, thereby performing measurement during calibration. The aim is to provide a zirconia gas analyzer with no time error.

[0008]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention is a zirconia gas analyzer for determining the concentration in a measurement gas from the electromotive force of a zirconia sensor composed of a zirconia solid electrolyte made of an oxygen ion conductor. It consists of a tube inserted into the tube and a gas introduction tube that introduces a calibration gas into the space formed by the outer circumference of this tube and the inner circumference of the zirconia tube. It is configured so that it is introduced into the space of the tube body and the zirconia tube on the mouth side, hits the internal electrode located at the bottom of the zirconia tube, and is discharged into the measurement gas. At the same time, a gas flow velocity delay means is provided in the space. It is characterized by that.

[0009]

[Action]

 The calibration gas is introduced into the space formed by the outer circumference of the tube and the inner circumference of the zirconia tube, and strikes the internal electrode located at the bottom of the zirconia tube and is discharged into the measurement gas. The calibration gas is sufficiently heated while passing through the gas flow velocity delay means provided in the space.

[0010]

【Example】

 FIG. 1 is a cross-sectional view of an essential part showing an embodiment of a zirconia gas analyzer according to the present invention. In the figure, the same parts as those in FIG. 2 are denoted by the same reference numerals and the duplicated description is omitted, but reference numeral 20 denotes a tubular body having a folded portion 20a and a cylindrical portion 20c having a threaded portion 20b formed on the outer periphery thereof. ing. Reference numeral 4a is a first cover plate fixed to the tip of the probe pipe 6 by welding, and the outer periphery of the folded portion 20a of the tubular body 20 is airtightly fixed near the center of the cover plate. Reference numeral 4b is a second cover plate screwed to the first cover plate. In this fixed state, the bottom of the zirconia tube 1 and the tip of the tubular body 20c face each other with a slight gap a left therebetween. The inner circumference of the folded portion 20a and the outer circumference of the zirconia tube 1 are airtightly fixed.

In the above configuration, the calibration gas is supplied from outside the furnace as shown in FIG. 2 and is preheated by the heater 10 while passing through the calibration gas introduction pipes 7 and 7 ′. Next, the calibration gas is introduced into the space between the zirconia tube 1 and the cylindrical portion 20c. Then, the calibration gas flows while rotating in a gap formed by the screw portion 20b and the cylindrical body 20c, is sufficiently heated by the heater 10 during this time, and is vaporized when there is a drain. The heated gas is ejected from the bottom of the zirconia tube 1 and the tip of the cylindrical body 20c, comes into contact with the internal electrode, and then flows out to the measurement gas side. Then, the measurement gas filled in the zirconia tube is removed.

Although the screw-shaped space is formed as the gas flow velocity delay means in the above embodiment, the invention is not limited to this example. For example, a convex ring is formed on the outer periphery of the cylinder at a predetermined distance, and a notch is provided in each part of the ring to delay the speed at which the calibration gas travels to the tip of the cylinder 20c. The point is that the shape is such that the calibration gas exiting the inlet tube 7 ′ reaches the tip via a long path.

[0013]

[Effect of the device]

 According to the present invention, as described in detail in connection with the above embodiments, the gas flow velocity delay means is provided while the calibration gas travels between the zirconia tube and the cylindrical portion 20c, so that the calibration gas is sufficiently heated. can do. Therefore, even if the calibration gas is brought into contact with the electrode, the electrode is not cooled. Therefore, since there is no temperature difference between the electrodes during calibration and measurement, a zirconia gas analyzer with no error can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of the essential parts of a zirconia gas analyzer showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a zirconia gas analyzer showing a conventional example.

FIG. 3 is a cross-sectional view of the essential parts of a zirconia gas analyzer showing another conventional example.

[Explanation of symbols]

 1 zirconia tube 4a, 4b cover plate 6 prober pipe 7, 7'calibration gas introduction tube 10 heater 16a internal electrode 16b external electrode 20 tube body

Claims (1)

[Scope of utility model registration request] 1. A zirconia gas analyzer for determining the concentration in a measurement gas from the electromotive force of a zirconia sensor composed of a zirconia solid electrolyte composed of an oxygen ion conductor,
The zirconia sensor is composed of a tube body inserted into a zirconia tube and a gas introduction tube for introducing a calibration gas into a space formed by the outer circumference of the zirconia tube and the inner circumference of the zirconia tube. The gas is introduced into the space between the zirconia tube and the zirconia tube on the side of the measurement gas inlet of the zirconia tube, hits an internal electrode arranged at the bottom of the zirconia tube, and is discharged into the measurement gas. A zirconia gas analyzer characterized in that a flow velocity delay means is provided.