JPS62147355A - Method and apparatus for calibrating gas of oxygen detector - Google Patents

Abstract

PURPOSE:To enable the reduction in the use amount of calibration gas, by performing calibration by sending not only reference gas to the side of an external electrode but also calibration gas to the side of an internal electrode. CONSTITUTION:To a protective pipe body 1, a reference gas introducing hole 51 for introducing reference gas into the gap between said pipe body 1 and a solid electrolyte 4 from the outside is provided. Further, a gas introducing pipe 52 connected to both of reference gas flow pipes 40, 41 and a calibration gas flow pipe 42 to introduce the gas from both flow pipes is provided to the hollow part of the electrolyte 4. At the time of the detection of oxygen concn., the inflow of reference gas from the introducing port 51 is prevented and only the reference gas is made to flow in the introducing pipe 52 from the flow pipes 40, 41. At the same time, an inflow gas control apparatus, wherein the reference gas is made to flow in from the introducing port 51 at the time of calibration and only calibration gas is made to flow in the introducing pipe 52 from the flow pipe 42, is provided. Further, a calibration circuit performing the calibration of the detection output of an oxygen detector on the basis of the electrical output generated between external and internal electrodes 2, 3 at the time of calibration is provided. By this method, it is sufficient to fill the space in the side of the electrode 3 reduced in a volume with calibration gas and the use amount of the calibration gas can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas calibration method and device for an oxygen detector that detects the oxygen concentration in dusty gas inside a furnace or an exhaust gas treatment device.

(Prior Art) Conventionally, an oxygen detector capable of gas calibration has been proposed, for example, as shown in Japanese Patent Application Laid-Open No. 57-51898.

The schematic configuration of the oxygen detector shown in the above publication is the fourth
It is as shown in the figure.

A bottomed cylindrical oxygen ion conductive solid electrolyte (hereinafter simply referred to as “
An external electrode 2 and an internal electrode 3 are fixed to the inner and outer surfaces of the closed end of a solid electrolyte (hereinafter referred to as "solid electrolyte") 4, and the solid electrolyte 4 is housed inside a metal protective tube body 1.

A 59 gas introduction pipe 18 for introducing a reference gas is inserted into the hollow portion of the solid electrolyte 4.

14 is the connecting pipe.

Further, a screen plate 22 having a large number of small holes is provided inside the protective tube body 1 at a position a little distance from the tip of the solid electrolyte 4, and the screen plate 22 allows the inside of the protective tube body 1 to be are partitioned to form a gas chamber 21.

When detecting the oxygen concentration, the internal electrode 3 is exposed to the reference gas by feeding the reference gas into the reference gas introduction pipe 18, and the external electrode 2 is inserted into the gas chamber 21 through the screen plate 22.
exposed to the gas to be measured (exhaust gas, etc.) flowing into the chamber. In this state, the lead wire 1 is electrically connected to the external electrode 2 and the internal electrode 3.
The oxygen concentration in the gas to be measured is detected by measuring the electrical output output through the 0.11.

On the other hand, when calibrating the detection output of the oxygen detector, a calibration gas (gas adjusted to a predetermined concentration) is supplied from the calibration gas supply pipe 23 provided between the holding fitting 12 and the mounting seat 7. and fills the gas chamber 21. A reference gas is supplied to the internal electrode 3 in advance.

In this state, the detection output is measured and calibrated.

Further, in order to eliminate clogging of the screen plate 22 and dust adhering to the outer surface of the solid electrolyte 4, the dust is blown away by an air flow (air purge). This air purge is performed by sucking air through the suction hole 8 formed in the mounting seat 7 through the gas condenser 24 and the motor valve 17.

That is, by opening the motor valve 17 while the inside of the furnace where the oxygen detector is attached is under negative pressure, air is sucked in and flows vigorously through the gas chamber 21.

Note that the partition plate 22 is provided to allow the calibration gas to easily accumulate in the gas chamber 21 during calibration.

(Problems to be Solved by the Invention) However, the above conventional calibration method for oxygen detectors has the following problems.

■ Because the pressure inside the furnace is low when an oxygen detector is installed,
A large amount of the calibration gas sent into the gas chamber 21 is sucked into the furnace, and in order to fill the gas chamber 21 with the calibration gas, it is necessary to flow a large amount of the calibration gas.

(2) The screen plate 22 provided to form the gas chamber 21 becomes clogged with dust in the furnace in a short period of time, so air purging is often performed.

Therefore, a gas condenser is required to store a large amount of air.

■ When performing an air purge, room temperature air is blown onto the outer surface of the heated solid electrolyte, so there is a risk of damage to the solid electrolyte due to thermal shock or moisture contained in the air. It is not recommended to do so.

■ In addition, some conventional oxygen detectors do not have the screen plate 22, and in this case, not only do they require a large amount of calibration gas during calibration, but in some cases, calibration may not be possible correctly. be.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a gas calibration method for an oxygen detector in which a reference gas is sent to the external electrode side to expose the external electrode to the reference gas. , calibration gas is sent to the inner electrode side, and calibration is performed with the internal electrodes exposed to the calibration gas.

Further, as an apparatus for implementing the above method, a reference gas introduction hole for introducing a reference gas from the outside between the protective tube body and the oxygen ion conductive solid electrolyte is provided in the protective tube body of the oxygen detector, and the A gas introduction pipe is provided in the hollow part of the oxygen ion conductive solid electrolyte, and is connected to both the reference gas delivery pipe and the calibration gas delivery pipe to introduce gas from these delivery pipes. At the time of concentration detection, the reference gas is prevented from flowing through the reference gas introduction hole, and only the reference gas from the reference gas transmission pipe is allowed to flow into the gas introduction pipe, and
an inflow gas control device that allows a reference gas to flow in from the reference gas introduction hole during calibration, and allows only the calibration gas from the calibration gas delivery pipe to flow into the gas introduction pipe; and a calibration circuit that calibrates the detection output of the oxygen detector based on the electrical output generated by the oxygen detector.

(Function) According to the method and apparatus of the present invention, the reference gas is sent to the external electrode side of the oxygen detector, and the calibration gas is sent to the internal electrode side to perform calibration, thereby reducing the space on the internal electrode side, which has a small volume. It is sufficient to fill the chamber with calibration gas, and the amount of calibration gas used can be significantly reduced compared to the conventional method.

In addition, since the reference gas only needs to flow into the external electrode side during calibration, air purge can be performed at the same time using the reference gas, and gas retention is not required as much as with conventional calibration gas. , it is also possible to eliminate the screen plate. Therefore, if this screen plate is eliminated, there is no need to worry about clogging.

(Example) Calibration according to an example of the present invention is shown in FIG. In the figure, the same reference numerals are given to the same components as those of the conventional example shown in FIG. 4.

The oxygen detector 100 used in this embodiment has a solid electrolyte 4 housed in a protective tube body 1, similar to the conventional oxygen detector shown in FIG.

Further, the present embodiment does not have the calibration gas feed pipe 23, which was present in the conventional example. Further, the portion that was the suction hole 8 in the conventional example has become the reference gas introduction hole 5I, and the portion that was the reference gas introduction pipe 18 has become the gas introduction pipe 52.

Furthermore, the present embodiment does not have the screen plate 22 that was present in the conventional example, and spiral blades 6 are provided between the outer surface of the solid electrolyte 4 and the inner surface of the protective tube body 1. The blades 6 are formed on the outer periphery of the fixed tube 5 and are press-fitted onto the outer periphery of the solid electrolyte 4 to be fixed therein.

FIG. 2 shows a cross-sectional view of the oxygen detector 100. In this embodiment, four blades 6A, 6[1, 6C, 6
D are arranged at 90° intervals, and these blades are spirally wound. However, the number of blades 6 is not limited to four.

The reference gas introduction hole 51 is provided with a reference gas passage pipe 40.
A reference gas passage pipe 41 and a calibration gas passage pipe 42 are connected to the gas introduction pipe 52 via a connecting pipe 14 and a connecting pipe 16 that branches into two.

The reference gas delivery pipes 40, 41 are adapted to receive air as a reference gas, and are either open to the atmosphere or connected to an air pump. Further, the calibration gas passage pipe 42 is connected to a reference gas cylinder.

A motor valve 17 is provided in the pipe line of the reference gas transmission pipe 40.
, and electromagnetic valves 25 and 26 are provided in the reference gas communication pipe 41 and the calibration gas communication pipe 42 . These motor valve 17 and electromagnetic valve 2
5 and 26, the opening and closing operations are controlled by the valve controller 31 using electric signals 5t-52, S:l.

The measuring device 32 receives the detection outputs S and S6 of the oxygen detector IQQ output from the leads Ig10 and Ig11, and measures the oxygen concentration and calibrates the detection output. It also provides a valve switching command signal S4 to the valve controller 31.

In the oxygen detector 100, the mounting seat 7 is preferably in the shape of a flange, and the four base gas holes 51 may be provided not only at one location but at multiple locations. In addition, the right end portion of the fixed tube 5 in the figure is fixed to the holding fitting 12,
The green leads 10 and 11 are configured to protrude from the end of the fixed tube 5. The holding fitting 12 and the fixing fitting 13 are
It is housed in a metal box 9 separate from the protective tube body 1, and the box 9 is closed with a lid 15.

Further, it is preferable that the blade 6 be wound around the fixed tube 5 five or more times. And this feather 6 is
It is not necessary to have a spiral shape. For example, as shown in FIG. 3, a plurality of disks 34 are attached to the fixed tube 5, and through holes 35 are formed in these disks 34 so that the opening positions are alternated. However, blades with a structure that prevents the flowing gas from going straight are also effective.

Further, the number of the blades is preferably set to a number necessary for heating the inflowing gas to about 150° C. before it reaches the vicinity of the external electrode 2, for example. That is, the number of blades is set in consideration of the heating temperature of the inflow gas depending on the temperature of the gas to be measured.

The fixed tube 5 is airtightly attached to a holding fitting 12, and this holding fitting 12 is further airtightly attached to the box 9. By attaching the holding fitting 12 to the box 9 in this manner, the solid electrolyte 4 is housed within the protective tube body 1.

The gas introduction pipe 52 is fixed by the fixing fitting 13, inserted into the hollow interior of the bottomed cylindrical solid electrolyte 4, and held therein. The open end of this gas introduction pipe 52 is located near the internal electrode 3.

The operation of the apparatus of this embodiment configured as above will be explained below.

First, when measuring the oxygen concentration in the furnace to which the oxygen detector 100 is attached, the measuring device 32 is instructed to perform a measuring operation by operating an external switch.

As a result, from the measuring device 32 to the valve controller 3
1, a command signal S4 is issued, and the valve controller 3
1 outputs signals 31 to S3 to close the motor valve 17 and the electromagnetic valve 26 and open the electromagnetic valve 25.

Therefore, around the external electrode 2 of the oxygen detector 100;
Gas to be measured (gas in the furnace) flows in through the opening of the protective tube body 1 , and reference gas is supplied to the internal electrode 3 via the gas introduction pipe 52 .

In this state, the detection output S1. The calculation device 32 manually measures the oxygen concentration.

On the other hand, during calibration, by instructing the measuring device 32 to perform a calibration operation, a command signal S4 is sent to the valve controller 31, and the valve controller 31
7 and outputs signals 31 to S3 to open the electromagnetic valve 26 and close the electromagnetic valve 25.

Therefore, the reference gas is sucked by the negative pressure in the furnace and flows into the external electrode 2 side of the oxygen detection 2B100 from the reference gas introduction hole 51. Further, a calibration gas is supplied to the internal electrode 3 via a gas introduction pipe 52.

The gas, that is, the air that flows in from the basic gas introduction hole 51 flows around the solid electrolyte 4 by one blade 6, and by the time it reaches the vicinity of the external electrode 2, it passes through the blade 6 and the protective tube body. Since the solid electrolyte 4 is warmed by the heat of the solid electrolyte 4, no thermal shock is applied to the solid electrolyte 4.

Furthermore, since the amount and speed of the air flowing in from the reference gas introduction hole 51 is large and high-speed, the reference gas is used as an air purge gas to prevent dust adhering to the solid electrolyte 4, external electrode 2, etc. from being blown away. gas flow is available.

Then, when the reference gas is in sufficient contact with the external electrode 2 and the calibration gas is supplied to the internal electrode 3, the detection output S-
, , Sb are measured by the measuring device 32 and calibrated.

At this time, the polarities of the input detection outputs S and S6 are opposite to the polarities of the detection outputs S and S when measuring the oxygen concentration. Change the polarity to the oxygen concentration 4tj by exchanging the input paths of SS and S6, or by using calculations or inverting circuits in the calculator.
l Correct the condition to be the same as the scheduled time.

With this calibration method, the calibration gas only needs to flow into the hollow part of the solid electrolyte 4, so the amount used can be significantly reduced compared to the conventional case where it flows into the external electrode 2 side. can be reduced. To give a specific example, conventionally, a large amount of calibration gas of 1 ON/min or more was required, but with the above example device, approximately 50 cc of calibration gas is required.
/mi,n, and the amount is about 1/200.

Moreover, as a result, the time required for gas exchange between calibration and oxygen concentration measurement can be significantly shortened in the above embodiment. That is, since the time required for calibration is short, it is possible to perform calibration frequently during oxygen concentration measurement, and detection accuracy can be improved.

In addition, since the oxygen detector 100 used in the above embodiment does not have a screen plate, as in the conventional example shown in FIG.
The screen plate 22 will not be clogged.

Furthermore, if the reference gas introduced during the calibration is sucked in by the negative pressure inside the furnace, there is no need for a gas condenser or piping equipment for compressed air as in the prior art.

Note that the above embodiment shows an example in which the reference gas is supplied to the external electrode 2 side and the calibration gas is supplied to the internal electrode 3 side during calibration. It is better to perform calibration by supplying the calibration gas to the external electrode 2 side and the reference gas to the internal electrode 3 side only when performing the above, and use the same method as in the above example for subsequent calibrations. Can be calibrated.

Further, in the above embodiment, the screen plate 22 is used as an oxygen detector.
Although we have shown an example using one without and with blades 6,
The present invention is not limited to this, but includes a screen plate 22,
Alternatively, it is also applicable even if there is no blade 6.

Furthermore, in the above embodiment, the selection of the supply gas was automatically performed using the valve controller 31, but in the present invention, the selection of the supply gas is performed manually by opening and closing valves and cocks. It may also be a method of making a selection.

Further, although the present invention has shown an example in which an oxygen detector having a bottomed cylindrical solid electrolyte 4 as a base is used,
For example, JP-A-59-1
An oxygen detector using an elongated plate-shaped solid electrolyte as a base as shown in No. 31158 may also be used.

(Effects of the Invention) As explained in detail above, according to the method and apparatus of the present invention, calibration can be performed by sending a reference gas to the external electrode side of an oxygen detector and sending a calibration gas to the internal electrode side. It is sufficient to allow the calibration gas to flow into the space on the internal electrode side, which has a small volume, and the amount of calibration gas used can be significantly reduced compared to the conventional method.

In addition, since it is only necessary to flow 14 gases into the external electrode side during calibration, air purge can be performed at the same time using fit3J gas, and gas retention is not required as much as with conventional calibration gases. Therefore, it is also possible to eliminate the screen plate. Therefore, if you eliminate this screen board,
You no longer have to worry about guessing.

Therefore, the present invention can be widely used in oxygen concentration meters and the like that measure the oxygen concentration in dusty gas inside a furnace or an exhaust gas treatment device.

Furthermore, by providing the blades in the oxygen detector as in the above embodiment, the thermal shock of the reference gas flowing into the external electrode side can be used during calibration, and damage to the solid electrolyte can be prevented.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an embodiment of the device according to the present invention, Fig. 2 is a cross-sectional view of the oxygen detector shown in Fig. 1, and Fig. 3 shows another example of the blade provided in the oxygen detector. The vertical sectional view shown in FIG. 4 is a configuration diagram of a conventional example. ■... Protection tube body 2... External electrode 3... Internal electrode 4... Solid electrolyte 6... Feather Jl
17...Motor valve 25, 26...Solenoid valve 31...Valve controller 32...Measuring device

Claims (1)

[Claims] 1. Oxygen detection comprising an external electrode exposed to a gas to be measured during oxygen concentration detection and an internal electrode exposed to a reference gas on the inner and outer surfaces of a base made of an oxygen ion conductive solid electrolyte. In a gas calibration method for an oxygen detector in which the detection output of the sensor is calibrated using a calibration gas, at the time of calibration, a reference gas is sent to the external electrode side, the external electrode is exposed to the reference gas, and the calibration gas is applied to the internal electrode side. A method for gas calibration of an oxygen detector, characterized in that calibration is performed with internal electrodes exposed to calibration gas. 2. At the closed end of a hollow oxygen ion conductive solid electrolyte with one end closed, an external electrode that is exposed to the gas to be measured when oxygen concentration is detected is provided on the outer surface, and an internal electrode is provided on the inner surface of the closed end of the oxygen ion conductive solid electrolyte. In a gas calibration device for an oxygen detector that calibrates the detection output of an oxygen detector whose outer peripheral surface is surrounded by a protective tube, the protective tube and the oxygen ion conductivity are connected to the protective tube of the oxygen detector. A reference gas introduction hole for introducing a reference gas from the outside is provided between the solid electrolyte and the hollow part of the oxygen ion conductive solid electrolyte is connected to both a reference gas communication pipe and a calibration gas communication pipe. , a gas introduction pipe for introducing gas from these communication pipes is provided, and when oxygen concentration is detected, the reference gas is prevented from flowing through the reference gas introduction hole, and the reference gas delivery pipe is connected to the gas introduction pipe. an inflow gas control device that allows only a reference gas to flow in from the calibration gas passage pipe, and that, during calibration, flows the reference gas from the reference gas introduction hole and flows only the calibration gas from the calibration gas transmission pipe into the gas introduction pipe; A gas calibration device for an oxygen detector, comprising a calibration circuit that sometimes calibrates a detection output of the oxygen detector based on an electrical output generated between the external electrode and the internal electrode.