JPH01206255A - Method and apparatus for analyzing concentration of oxygen - Google Patents

Abstract

PURPOSE:To calibrate an oxygen concn. cell without using standard gas, by allowing a pump current to flow to the oxygen pump part of an oxygen sensor element and bringing the atmosphere above the gas electrode to be measured of the oxygen concn. cell of the oxygen sensor element to one having the same oxygen concn. as a calibration gas to perform calibration. CONSTITUTION:The measuring chamber 18 of an oxygen sensor element 10 set to predetermined temp. by a heater part 40 is filled with a calibration gas containing oxygen at every concn. and the reference generated power E0 of an oxygen concn. cell part B corresponding to the concn. O2 of oxygen in the calibration gas is calculated. Further, the chamber 18 is brought to the atmosphere of the open air to calculate a reference oxygen pump current IPC wherein the generated electromotive force of the cell part B corresponds to the power E0 by supplying a current to pump electrodes 12, 13. When the element 10 is calibrated, the current IPC is allowed to flow to an oxygen pump part P in such a state that the atmosphere is allowed to flow to the element 10 to bring the atmosphere of the chamber 18 to a prescribed oxygen concn. and the generated electromotive force of the cell part B generated corresponding thereto is calibrated to the voltage E0 through a buffer amplifier.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an oxygen concentration analysis method used in industrial oxygen analyzers, particularly small boilers, water heaters, factory furnaces, oxygen deficiency monitors, air-fuel ratio meters, etc. and its equipment.

(Prior art) Conventionally, as an oxygen analyzer based on the principle of an oxygen concentration battery, there is an oxygen analyzer that exposes the standard reference electrode of an oxygen concentration battery formed of a solid electrolyte to the atmosphere, and an oxygen analyzer based on the principle of an oxygen concentration battery.
As disclosed in the above publication, an oxygen analyzer is known in which the standard reference electrode of an oxygen concentration cell is brought into an atmosphere with a standard oxygen concentration using an oxygen pump.

In these oxygen analyzers, the solid electrolyte and electrodes change over time, so Japanese Industrial Standard B7983, KO
As described in 055, in order to accurately measure the oxygen concentration of the measurement gas, the electromotive force of the oxygen concentration cell was calibrated using a standard gas.

(Problem to be Solved by the Invention) However, in order to perform the above calibration, it is necessary to provide the oxygen concentration analyzer with a conduit for guiding the standard gas to the measurement electrode of the oxygen concentration battery. For this reason, the structure of the apparatus becomes complicated and the apparatus itself becomes large, and at the same time, it is complicated to prepare a standard gas having a predetermined oxygen concentration each time the calibration is performed.

The purpose of the present invention is to solve the above problems,
It is an object of the present invention to provide an oxygen concentration measuring method that can calibrate an oxygen concentration cell without using a standard gas, and an apparatus used therefor.

(Means for Solving the Problems) The first oxygen concentration analysis method of the present invention is an oxygen concentration analysis method using an oxygen concentration battery method using a solid electrolyte.
An oxygen concentration analysis characterized in that calibration is performed by applying a pump current to the oxygen pump section of the oxygen sensor element and creating an atmosphere with an oxygen concentration equivalent to that of the calibration gas over the measured gas electrode of the oxygen concentration cell of the oxygen sensor element. It's a method.

Furthermore, the second oxygen concentration analysis method of the present invention, in summary, calibrates an oxygen sensor element having an oxygen concentration battery and an oxygen pump section with an oxygen pump current, which has a reference electrode using the atmosphere as a standard reference gas. This is an oxygen concentration analysis method characterized by the following.

Further, in summary, the third oxygen concentration analysis method of the present invention includes an oxygen sensor element having two oxygen pump sections and an oxygen concentration battery that drives one of the oxygen pump sections and uses it as a reference gas. This is an oxygen concentration analysis method characterized by performing calibration using oxygen pump current.

The first oxygen concentration analyzer of the present invention includes (a) an oxygen sensor element that has a reference gas chamber communicating with the atmosphere and a measurement chamber communicating with the gas to be measured, and is equipped with an oxygen concentration battery and an oxygen pump section. , (b) Calibration gas oxygen concentration (O2), standard generated electromotive force (E0), and pump current (L
(c) Memorize the relationship between the pump current (1, c) that flows through the oxygen pump section when measuring the oxygen concentration of the sample gas, and the electromotive force (v5) of the oxygen concentration battery. The relationship is manually determined, and the reference generated electromotive force (B11) and electromotive force (VS) are calculated by referring to the relationship between the pump current (1, c) of the memory circuit and the reference generated electromotive force (E0).
and calculate the relationship between the measured electromotive force (VS) generated by the gas to be measured and the reference generated electromotive force (E0) and the electromotive force (
This oxygen concentration analyzer is characterized by comprising a calibration circuit that calculates the oxygen concentration (O2) corresponding to the measured electromotive force (VS) with reference to the relationship with the measured electromotive force (VS).

Furthermore, the second oxygen concentration analyzer of the present invention comprises (a)
A reference gas chamber communicating with the gas to be measured, a first oxygen pump portion formed in one of the reference gas chambers, an oxygen concentration battery formed in the other side of the reference gas chamber, and communicating with the gas to be measured. an oxygen sensor element comprising a measurement chamber and the oxygen concentration battery formed in one of the measurement chambers and a second oxygen pump section in the other; (b) connected to the first oxygen pump section; The present invention is an oxygen concentration analyzer characterized by comprising: an oxygen pump section current generation source; (c) a memory circuit similar to the oxygen concentration analyzer described above; and (d) a calibration circuit.

(Function) The main point of the present invention is to obtain a one-to-one correspondence between a known standard oxygen concentration, a standard generated electromotive force, and a pump current by verifying with a calibration gas in advance, and to use the atmosphere as a standard reference gas. Place the oxygen sensor element in the atmosphere and apply a known standard oxygen pump current to create an atmosphere with an oxygen concentration equivalent to that of the calibration gas at the measurement electrode of the oxygen concentration battery, and calibrate the electromotive force output from the oxygen concentration battery in advance. This method and apparatus measure the oxygen concentration of the measured gas by calibrating it to a standard generated electromotive force and placing an oxygen sensor element in the measured gas.

(Example) The oxygen concentration analysis method and apparatus of the present invention will be described below with reference to the drawings.

Example 1 The first example is an oxygen concentration analyzer in which atmospheric air is used as a reference gas (oxygen concentration) in an oxygen concentration battery that calibrates an oxygen sensor element that is a detection section for a measurement gas.

As shown in FIG. 1, the oxygen sensor element 10 constituting the detection section has an integrated structure made up of a plurality of stacked layers, and includes, in order from the top, an oxygen pump section P1, an oxygen concentration battery section B, and a heater section H. It consists of

First, the upper oxygen pump section P has a solid electrolyte body 11, and an upper pump electrode 12 and a lower pump electrode 13 are formed on both upper and lower sides of the solid electrolyte body 11. The electrode wires of the pump electrodes 12 and 13 are connected to the solid electrolyte body 11, respectively.
The electrode terminal (not shown) is provided on the side surface of the electrode terminal. The oxygen pump part P is exposed to the measurement gas,
A gas introduction hole 14 through which the measurement gas is introduced is provided.

The intermediate oxygen concentration battery section B, like the oxygen pump section P, has a solid electrolyte body 15, and a measurement electrode 16 and a reference electrode 17 are formed on both the upper and lower sides of the solid electrolyte body 15. The reference electrode 17 and one electrode 13 of the oxygen pump section P are each grounded.

An insulating space member 19 having a predetermined thickness is interposed between the oxygen concentration battery section B and the oxygen pump section P to form a measurement chamber 18 which is a narrow space into which the measurement gas is introduced. Furthermore, the gas introduction hole 14 communicates with the central portion of the measurement chamber 18 . Furthermore, the measurement electrode 16 faces the measurement chamber 18 .

The lower heater section H is formed below the oxygen concentration battery section B via the solid electrolyte body 20, and is connected to the oxygen sensor element lO.
1. In particular, the oxygen concentration battery section B is heated to a predetermined temperature. The heater portion H is formed by covering the heater element 21 with a porous layer 22 made of alumina or the like having electrical insulation properties.

Note that a thermocouple T is attached to the lower part of the heater section H to measure the heating temperature, that is, the temperature of the oxygen sensor element 10, and the temperature can be controlled from this measured value.

Between the solid electrolyte body 20 and the oxygen concentration battery section B,
A space member 23 of a solid electrolyte body is interposed, and a reference gas chamber 24 is formed in a region where the reference electrode 17 is exposed. This reference gas chamber 24 communicates with the atmosphere.

Solid electrolyte body 1, 15.20 and space member 19
．． 23 are each constructed from stabilized or partially stabilized zirconia porcelain that exhibits oxygen ion conductivity at high temperatures.

The pump electrodes 12, 13, measurement electrode 16, and reference electrode 17 are each made of porous platinum or the like, and are layered with gas-permeable porous ceramics made of alumina or the like to protect these electrodes from high-temperature or corrosive measurement gases. Preferably, it is coated with.

For example, the heater element 21 may be arranged by printing a paste containing alumina powder and platinum powder as main components, or
Alternatively, it may be formed by a method such as arranging a cermet-like film. Further, the thermocouple T can be formed by printing and laminating a combination of thin metal wires, pastes, or cermets made of different metals.

The detection circuit of the oxygen sensor element of the detection section having the above structure will be explained based on the block diagram of FIG. 2.

Terminals of the upper pump electrode 12 of the oxygen pump section P in FIG.
a) is connected to the output terminal of the oxygen pump current generation source 31, and the storage circuit 3 is connected to the input terminal of the oxygen pump current generation source 31.
3 is connected to the output end of a control device 32 having a built-in controller.

The control device 3 based on the data stored in the storage circuit 33
2 controls the output current value of the oxygen pump current generation source 31. An external human input device 34 is connected to the control device 32 to enable manual input of the data necessary for the calibration of the oxygen sensor element IO.

In addition, the terminal (b) of the reference electrode 17 of the oxygen concentration battery section B in FIG. The electromotive force generated in the battery section is converted into a reference electromotive force value. The output end of the calibration circuit 36 is connected to the input end of an open number converter 37, where it is converted into a numerical value suitable for oxygen concentration display, and the converted numerical signals are sent to the display device 38 and output converter 39, respectively. is transferred. In the output converter 39, the manually input signal is further converted into a desired signal form and output as an output signal.

Furthermore, the terminal (C) of the heater element 21 of the heater section H in FIG.
The voltage obtained at the terminal (d), buffer amplifier 4
1. The voltage is supplied through the cold junction 42'J6 and the amplifier 43, after being compared with the voltage of the reference temperature setting circuit 44. The heater temperature controller 40 controls the power supplied to the heater section H based on the detected voltage corresponding to the temperature of the thermocouple T.

A method of calibrating the oxygen sensor element 10 of the oxygen concentration analyzer configured as described above will be described below with reference to FIGS. 1 to 4.

(A) Verification of oxygen sensor element (1) The heater temperature controller 40 measures the temperature of the oxygen sensor element 10 with a thermocouple T and controls the heater section H to bring it to a predetermined temperature (for example, 800° C.).

(2) The measurement chamber 1B of the oxygen sensor element 10 is filled with calibration gas containing various oxygen concentrations, and the reference generated electromotive force ([E0 ). An example of the relationship between the standard generated electromotive force (E0) and the oxygen concentration (O□) obtained in this way is shown in FIGS. 4(a) and 5(a). The temperature of the oxygen sensor element 10 is preferably within the measurement gas temperature range.

(3) Next, the oxygen sensor element 10 is placed in the atmosphere or the measurement chamber 8 of the oxygen sensor element 10 is made into an atmospheric atmosphere by some means, and the oxygen pump current is gradually applied to the oxygen pump section P by the oxygen pump current generation source 31. The reference oxygen pump current (
1, find c).

An example of the relationship between the reference generated electromotive force (Eo) obtained in this manner and the reference oxygen pump current (I, c) is shown in FIGS. 4(b) and 5, etc.).

O: Verified standard oxygen pump current (Ip) △: Verified standard generated electromotive force (E0) B: Oxygen concentration in the measurement chamber 18 (O2) equivalent to the oxygen concentration of the calibration gas X: Verified in atmospheric atmosphere reference oxygen pump current (I
The generated electromotive force (VS) is generated in the oxygen concentration battery part (B) by flowing p) into the oxygen pump part (P). The standardized reference oxygen pump current (lpc) obtained by the above operation is The oxygen sensor element 1 is
The oxygen concentration in the measurement chamber 18 at 0 is equivalent to that of the calibration gas.

The oxygen concentration of the calibration gas obtained from the oxygen sensor element verification (
The relationship between the reference generated electromotive force (B0) and the reference oxygen pump current (IPC) is input to the storage circuit 33 by the external input device 34.

It is preferable that the oxygen sensor element be verified before the oxygen sensor element is assembled into an oxygen concentration analyzer.

The reason for this is that the testing method is easy.

(B) Calibration of the oxygen sensor element This operation is performed as described in (A) when measuring the concentration of the sample gas using an oxygen concentration analyzer incorporating an oxygen sensor element.
This is to calibrate the difference between the measured value and the certified value of the oxygen sensor element.

As explained in the test (A) above, the reference oxygen pump current (IPC) is
By flowing the oxygen into the oxygen pump section P, the atmosphere in the measurement chamber 18 is brought to a specified oxygen concentration, and correspondingly, the generated electromotive force (VS) of the oxygen concentration battery section B is generated. can be calibrated to the reference generated electromotive force (B0) by adding/subtracting the bias and increasing/decreasing the gain of the buffer amplifier 35, or by changing a predetermined temperature, or by setting the generated electromotive force (VS) to Calibration is performed using several sets of broken line approximation calibration functions, with the electromotive force (E0) as Y.

This calibration is performed by a calibration circuit 36.

As shown in FIG. 5(C), the relationship between the generated electromotive force (VS) and the reference generated electromotive force (E0) is stored in the storage circuit 33.

(C) Measurement chamber 18 of oxygen sensor element 10 exposed to measurement gas
The measurement gas enters due to diffusion, a difference in oxygen concentration occurs between the measurement chamber 18 and the reference gas chamber 24, and an electromotive force (VS) is generated between the measurement electrode 16 and the reference electrode 170. The electromotive force (VS) is input to the calibration circuit via the buffer amplifier 35. The electromotive force (VS) is, as shown in FIG. 5(C),
3, the reference generated electromotive force (B0) is converted to a standard generated electromotive force (B0) by polygonal line interpolation, and this is converted to an appropriate value for oxygen concentration via the open number converter 37 and displayed on the display device 38.
It is displayed as an output signal through an output converter 39 that converts the range into a required range.

Next, hardware based on the block diagram of FIG. 2 of the present invention will be briefly explained with reference to FIG. 3.

The output from the oxygen concentration battery section B is passed through a low pass filter 350.
a and amplifier 351a to multiplexer 352. Similarly, the output from thermocouple T is passed through low pass filter 350b and cold junction 42 and amplifier 35.
1b to multiplexer 352. The output from the oxygen concentration battery section B further passes through an amplifier 353 to A/
After being sent to a D converter 360 where it is converted into a digital signal, the reference clock generation circuit 36 having a crystal oscillator is
1, and is calculated and stored in response to a command from a central control unit (CPU) 362 operating under the same system.

A timer counter 363 and a parallel input/output port 364 are connected to the A/D converter 360, and the CPU 362
A ROM 320 and a RAM 321 are connected to the ROM 320 and RAM 321.

The signal converted into a desired numerical value under the control of the CPU 362 is output via the D/A converter 390 and the output converter 391 on the one hand, and the D/A converter 322 on the other hand.
It is calibrated so that a predetermined current can be supplied to the bias oxygen pump section P via the bias setting device 323 when the switch 324 is opened. Furthermore, the parallel input/output port 381 has an indicator 380 for displaying oxygen concentration.
It is also connected to a heater temperature controller 400 for controlling the heater temperature, and to relays 401 and 402 for switching an external device, such as an alarm device or an emergency stop device.

An example of use of the oxygen concentration analyzer described above will be explained with reference to FIG.

The oxygen sensor element 1 is installed in a metal protection tube 3 via a disk-shaped support 2 made of alumina. The measurement gas concentration detection section S of the oxygen sensor element 1 removes dust from the measurement gas (
It is in contact with the measurement gas through a filter 4.

The metal protection tube 3 is attached via a flange 6 to a partition wall 5 between the measuring gas and the atmosphere, for example, to the wall of a flue of a combustion furnace.

The input and output of the electrode terminal and heater terminal of the oxygen sensor element 1 are connected to an external measurement and control circuit (not shown) by a lead wire 7 for use.

Example 2 The second example uses an atmosphere introduced by the oxygen pump part of the oxygen sensor element itself as a reference gas (oxygen concentration) for an oxygen concentration battery that calibrates the oxygen sensor element, which is the detection part of the measurement gas. This is a method and device for measuring oxygen concentration when using.

The structure of the oxygen sensor element constituting the detection section will be explained in detail with reference to FIG. 7. In the figures, components that are substantially the same as those described in the first embodiment are designated by the same reference numerals.

As shown in FIG. 7, the oxygen sensor element 1o mainly includes:
It consists of, in order from the top, an oxygen pump section P1 for calibration, an oxygen concentration battery section B'J3, and an oxygen pump section P2 for bias.

The differences from the oxygen sensor element of Example 1 will be explained below.

First, the upper calibration oxygen pump section P1 includes a solid electrolyte body 11a, an upper pump electrode 12a and a lower pump 13a arranged on both upper and lower sides of the solid electrolyte body 11a.
A heating section is formed around the upper pump electrode 12a by force with the former heater element 21a. Oxygen concentration battery part B
A sealing layer 50 made of a high-temperature airtight adhesive such as alumina cement is interposed at one end between the oxygen pump section P1 and the oxygen pump section P1, and the other end has an opening and communicates with the measurement gas. That is, the measurement chamber 18a is formed by the oxygen concentration battery section B, the oxygen pump section P1, and the sealing layer 5o.

Similarly to the oxygen pump section P1 for calibration, the lower bias oxygen pump section P2 includes a solid electrolyte body 11b1, an upper pump electrode 12b and a lower pump electrode 13b1 on both sides of the solid electrolyte body 11b1, and a heater element 21b around the lower pump electrode 13b. It consists of a heating section (2) having a heating section (2).

A sealing layer 50 is interposed at one end between the oxygen concentration battery section B and the oxygen pump section P2, and a reference gas chamber 24a is formed.

The measurement principle of the second oxygen concentration analyzer configured as described above will be explained below.

A bias oxygen pump current (1, 1
Difference in oxygen concentration (O2(B)) injected from the oxygen pump part P2 to the reference gas chamber 24a on the reference side when 1) is flowed
is kl・Ipn=D −A/I!・(O2(9'
−02(s))=D−A/I2・Δ0□”)(1) (where, kl: proportionality constant, Ipa: bias oxygen pump current, D: diffusion constant, A: diffusion cross section, l: diffusion Distance, 02 (9): Standard reference gas oxygen concentration, 0° (S) Oxygen concentration of the measurement gas, Δ0□ (E): Injected oxygen concentration), and from this equation (1), 0□ ( 9)=0□(S)+Δ02(B)(2), and the apparent difference in oxygen concentration by ΔQ2(B) has been injected into the reference gas chamber.Therefore, the electromotive force generated at the detection part is E,=RT/nFio,((O2(s)+0.(B)1
02(s)) (3), exp(nF/RT −Eis)=(Oz”'+02
”') 10□(s) > 1 (4) is obtained. From this, [1, (S) , ΔQ, (B) barexp(nF/RT
−80)−1)=k2・Ipa/(exp(nP/R
T-Es)-1) (5) (However, K2・Kl/D
-1! /A) is obtained. Based on this calculation formula (5),
For example, by a calculation means such as a computer, the oxygen concentration (O□(S)) in the gas to be measured can be determined from the generated electromotive force ε.

To summarize the above measurement principle, a constant oxygen pump current IPB is caused to flow through the bias oxygen pump section P2, and a constant amount that is known in advance from the oxygen concentration of the gas to be measured flows inside the reference gas chamber 24a on the reference side. The measurement is performed at a high oxygen concentration difference Δ02(B), that is, at a constant concentration difference. That is, accurate measurement of the measurement gas can be performed without using a reference gas.

Next, the detection circuit of the oxygen sensor element IO based on the above measurement principle will be explained with reference to the block diagram of FIG.

The upper pump electrode 12a of the oxygen pump part P1 for calibration is (
(indicated by a in the figure), oxygen pump current generation source 31a
, and the lower pump electrode 13a is grounded. The output end of the control device 32 is connected to the input end of the oxygen pump current generation source 31a. This control device 32
has a built-in storage device 33, and based on the data input to the storage device 33, the control device 32 controls the output current of the oxygen pump current generation source 31a to a predetermined value. Similarly, the lower electrode 13 of the bias oxygen pump section P2
b is connected to the output end of the oxygen pump current generating source 31b, and the upper electrode 12b is grounded. The input end of this oxygen pump current generating source 31b is also connected to the output end of the control device 32 (connected by symbol e in the figure). Furthermore, an external input device 34 is connected to the control device 32 so that data necessary for calibrating the oxygen sensor element 10 and other data can be entered manually.

The reference electrode 17 (indicated by the symbol in the figure) of the oxygen concentration battery section B is connected to the input terminal of the temperature correction circuit 520 via the digital filter 51. In this circuit, the output of the thermocouple T is passed through the digital filter 55, the temperature linearizer 56, and the absolute temperature converter 53 so that the apparent oxygen concentration due to the temperature change of the oxygen sensor element 10 corresponds to the above temperature change. The obtained signal regarding the absolute temperature Tk is sent to the temperature correction circuit 5.
2, where temperature correction is performed by multiplying the electromotive force generated by the oxygen concentration battery by 1000/Tk.

The output terminal of the temperature correction circuit 52 is connected to the input terminal of the calibration circuit 36. In the calibration circuit 36, the generated electromotive force corresponding to the measurement gas is converted into a reference electromotive force.

The output end of the calibration circuit 36 passes through an open logarithm conversion circuit 37, an oxygen concentration converter 54, and an output converter 39, undergoes range conversion, is converted into a predetermined value, and is then supplied to an output means such as a display unit. .

For example, when a thermocouple T is used in the temperature detection section, it is connected to a temperature linearizer 56 via a digital filter 55 in order to change the non-linear temperature-voltage characteristic to a linear temperature-voltage characteristic, and then the polygonal line is Perform interpolation correction. The output terminal of the temperature linear live 56 is connected to the input terminal of the absolute temperature converter 53 as described above, and also to the temperature setting circuit 5.
7 is connected to the temperature control calculator 59.
It is also connected to the input terminal of First, in the temperature setting circuit 57,
It is equipped with a soft start that increases the set voltage as the temperature rises, and outputs a constant temperature set value at a desired temperature, and this output voltage is subtracted from the output voltage from the temperature linear drive 56 in a subtracter 58. Ru. In the temperature control calculator 59, for example, in a temperature range from room temperature to about 1400°C, if the operating temperature of oxygen pump parts P1 and P2 and oxygen concentration battery part B is below (for example, about 600°C), these parts are It calculates and outputs a predetermined current to the heater section 112 via the output converter 60 connected at the subsequent stage so that the temperature is maintained at a predetermined temperature.

In addition, if the oxygen pump parts Pi, P2 and oxygen concentration battery part B exceed the operating range due to the gas to be measured, the heating part old and H2 may continue to be heated, or the temperature linearizer 56 may It is also possible to cut off the heater current using a switch in the temperature control calculator 59 when the voltage exceeds a predetermined value. In either case, temperature is detected and temperature correction calculations are always performed, so there is an advantage that accurate oxygen concentration can always be measured regardless of temperature.

Next, operations for performing calibration according to the present invention will be explained.

This embodiment differs from the first embodiment in that it includes a second oxygen pump section P2 and allows a bias oxygen pump current to flow therethrough.

First, the pump bias current IP of the bias oxygen pump section P2! 1 is predetermined based on the temperature range to be measured based on the above-mentioned equation (1).

Next, while the bias current IPB is flowing through the bias oxygen pump section P2, the calibration operation (A
) to (C).

FIG. 9 is a hardware diagram specifically showing the block diagram of FIG. 8. Since this is also a circuit similar to the hardware configuration diagram shown in FIG. 3 as a specific example of the first embodiment, the same parts are denoted by the same reference numerals.

The difference here is that the input device 62 is connected to the parallel input/output port 364, and the plurality of parallel input/output ports 3
65-369 is CPt1362 (7) Lord Hasni [1
The point is that an output signal is output from each. Such a circuit can be implemented either using a multi-chip CPU or using a single chip.

In the oxygen concentration analyzer of the second embodiment explained above, the first
As shown in Figure 0, an oxygen sensor element 10 as a detection section
is fixed to the metal protection tube 3 at its closed side C using a high-temperature insulating adhesive such as alumina cement so that its open side 0 is exposed to the gas to be measured. Inside the metal protection tube 3, a 10-sized alumina pipe 8, for example, is provided so as to lead the lead wire 7 from the oxygen sensor element 10 in an insulated state.
are inserted, and lead wires 7 from each electrode or heater wire are inserted into each hole. The base side of the metal protection tube 3 is attached to a flange 6.6', for example through an opening formed in the furnace wall of the flue of the combustion furnace. Attachment 7 The flange 6.6' are attached to each other via packings 127 and fixed to the furnace wall. A cap 9 is inserted into these flanges 6,6'. Further, during installation, the gap between the flange 6, 6' and the metal protection tube 3 is sealed with water glass or the like. Furthermore, outer electrode terminals 61 are provided inside the cap 9 and spaced apart by silicon packing or the like, and these electrode terminals 61 include
The lead wire 7 from the oxygen sensor element 10 passing through the alumina vibe 8 is connected via a crimp terminal to an external device (
(not shown).

Furthermore, for calibration during on-site use, periodically expose the detection section to internal air during use, and use the oxygen pump section P for calibration.
It is preferable to flow a pump current through the sensor 2 and calibrate the electromotive force generated in response to the pump current to correct the amount of change in drift of the detection section. This correction is processed by the calibration circuit 36.

By doing this, in addition to making it possible to calibrate with the oxygen pump part P1 during on-site use, the oxygen pump part P2 for bias eliminates the need to use a standard reference gas, so first, the detection part Since the air passage can be omitted, the detection section can be completely sealed, and there is no need to worry about moisture entering from the outside, making it possible to use it outdoors.

(Effects of the Invention) As is clear from the above description, the oxygen concentration analysis method and device according to the present invention have the following effects.

(1) Since the atmosphere can be used to calibrate the oxygen sensor element or the detection section, it can be easily carried out at the measurement site.

(2) Since the oxygen concentration for calibration can be obtained by the oxygen pump section for calibration, there is no need to prepare a special calibration gas.

(3) A conduit for calibration gas is not required, and the device can be made smaller.

(4) Since the history of changes in the standard generated electromotive force of the oxygen sensor element can be easily obtained, the lifespan of the oxygen concentration analyzer can be known.

Therefore, the method and apparatus of the present invention have great industrial applicability.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an oxygen sensor element according to an embodiment of the present invention, Fig. 2 is a block diagram of a detection section connected to the oxygen sensor element of Fig. 1, and Fig. 3 is a hardware configuration of Fig. 2. Fig. 4 is a schematic diagram for explaining the method for verifying the oxygen sensor element of the detection section, Fig. 5 is a schematic diagram for explaining the calibration method for the detection section, and Fig. 6 is a schematic diagram for explaining the method for calibrating the oxygen sensor element of the detection section. 7 is a sectional view of an oxygen sensor element according to an embodiment of the present invention; FIG. 8 is a block diagram of a detection section connected to the oxygen sensor element of FIG. 7; FIG. 9 is a block diagram of a detection section connected to the oxygen sensor element of FIG. FIG. 8 is a hardware configuration diagram, and FIG. 10 is a sectional view of an embodiment of the apparatus of the present invention. S...Detection section B...Oxygen concentration battery section P
, PI, P2...oxygen pump section 11, Hl,
H2...Heater part 0□, 0□(B), Δ0□(B)...Oxygen concentration 6°・
...Reference generated electromotive force Es, V, ...Generated electromotive force Ipct IPB...Oxygen pump current 1, 10...
Oxygen sensor elements 18, 18a...Measurement chambers 24, 24a...Reference gas chamber

Claims (1)

[Claims] 1. In an oxygen concentration analysis method using an oxygen concentration battery method using a solid electrolyte, a pump current is passed through the oxygen pump section of the oxygen sensor element, and a pump current is applied to the gas electrode to be measured of the oxygen concentration battery of the oxygen sensor element. An oxygen concentration analysis method characterized by performing calibration in an atmosphere with an oxygen concentration equivalent to that of the calibration gas. 2. In an oxygen concentration analysis method using an oxygen concentration battery method using an oxygen sensor element including an oxygen pump section and an oxygen concentration battery having a reference electrode using the atmosphere as a standard reference gas, (1) Detection of the oxygen sensor element A predetermined oxygen concentration (O_
2) Supply the calibration gas and measure the standard generated electromotive force (E_0) of the oxygen concentration cell to find the relationship between the oxygen concentration and the standard generated electromotive force. (2) Then, place the oxygen sensor element in the atmosphere. (3) Find the relationship between the pump current (I_P_C) and the standard generated electromotive force (E_0) by flowing a current (I_P_C) through the oxygen pump section of the oxygen sensor element until the reference generated electromotive force (E_0) is generated. Next, when measuring the oxygen concentration of the measurement gas, the oxygen sensor element is placed in the atmosphere, and a predetermined pump current (I_P_C) is passed through the oxygen pump section, so that the electrode of the measurement gas of the oxygen concentration cell is equal to the calibration gas. An atmosphere with an oxygen concentration of
After finding the relationship between C) and the electromotive force (V_S), use the above (2)
), the electromotive force (V
The oxygen sensor element is calibrated by finding the relationship between the electromotive force (E_0) and the electromotive force (E_0) generated in the oxygen concentration cell. (4) Next, the oxygen sensor element is placed in the gas to be measured, and the electromotive force ( V_m) and the electromotive force (V_m) as described in (3) above.
Through the calibration performed in (1) above, the reference generated electromotive force (E_0) and oxygen concentration (O
_2) An oxygen concentration analysis method characterized by measuring the oxygen concentration of a gas to be measured based on the relationship with _2). 3. Oxygen concentration analysis using an oxygen concentration battery method using an oxygen sensor element equipped with two oxygen pump units and an oxygen concentration battery, and using a predetermined pump current to flow through one oxygen pump unit as a reference gas for the oxygen concentration battery. In the method, (1) a predetermined oxygen concentration (O_
2) Supply the calibration gas and measure the standard generated electromotive force (E_0) of the oxygen concentration cell to find the relationship between the oxygen concentration (O_2) and the standard generated electromotive force (E_0). is placed in the atmosphere, and the pump current (I_P_C) is caused to flow through the other oxygen pump section until the reference generated electromotive force (E_0) is generated.
_P_C) and the standard generated electromotive force (E_0), (3) Then, when measuring the oxygen concentration of the measurement gas, place the oxygen sensor element in the atmosphere, and place the oxygen sensor element in the other oxygen pump part of the oxygen sensor element. A pump current (I_P_C) is applied to bring the oxygen concentration on the measured gas electrode of the oxygen concentration battery to the same level as that of the calibration gas, the electromotive force (V_S) generated in the oxygen concentration battery is determined, and the pump current (I_P_C) is calculated.
After finding the relationship between I_P_C) and electromotive force (V_S),
Calibrate the oxygen sensor element by determining the relationship between the electromotive force (V_S) and the reference generated electromotive force (E_0) based on the relationship in (2) above, (4) then place the oxygen sensor element in the gas to be measured,
Measure the electromotive force (V_m) generated in the oxygen concentration battery, and calculate the electromotive force (V_m) as described in (3) above.
Through calibration based on the relationship between the electromotive force (V_S) and the reference electromotive force (E_0), the oxygen concentration (O_2
) and a reference generated electromotive force (E_0) to measure the oxygen concentration of a gas to be measured. 4. An oxygen concentration analyzer using a solid electrolyte and an oxygen concentration battery system, (a) has a reference gas chamber communicating with the atmosphere and a measurement chamber communicating with the gas to be measured, and a reference electrode and a reference electrode on the side of the reference gas chamber. an oxygen sensor element comprising an oxygen concentration battery having a measurement electrode on the measurement chamber side; and an oxygen pump section facing the measurement electrode and having electrodes on the measurement chamber side and the measurement gas side; (b) a calibration gas; The relationship between the standard generated electromotive force (E_0) corresponding to the oxygen concentration (O_2) and the standard generated electromotive force (E_0
); and (c) an electromotive force of the oxygen concentration battery corresponding to the pump current (I_P_C) flowing through the oxygen pump section when measuring the oxygen concentration of the measurement gas. (V_S), the pump current (I_P_C) stored in the storage circuit and the reference generated electromotive force (E_0
), calculate the relationship between the standard generated electromotive force (E_0) and the electromotive force (V_S), and calculate the standard generated electromotive force (E_0) from the measured electromotive force (V_m) generated by the gas to be measured.
An oxygen concentration analyzer comprising: a calibration circuit that calculates an oxygen concentration (O_2) corresponding to a measured electromotive force (V_m) with reference to the relationship between the electromotive force (V_S) and the electromotive force (V_S). 5. An oxygen concentration analyzer using a solid electrolyte and an oxygen concentration battery system, which includes: (a) a first oxygen pump section, an oxygen concentration battery, and a second oxygen pump section; A reference gas chamber communicating with the gas to be measured is formed between the oxygen concentration cells, a measurement chamber communicating with the gas to be measured space is formed between the oxygen concentration cells and the second oxygen pump section, and the first oxygen The pump part introduces the gas to be measured as a reference gas into the reference gas chamber by a pumping action, and the second oxygen pump part introduces the gas to be measured into the measurement chamber by a pumping action, thereby filling the reference gas chamber and the measurement chamber. An oxygen sensor that generates an electromotive force between a reference electrode installed in the reference gas chamber side of an oxygen concentration battery and a measurement electrode installed in the measurement chamber side by applying a predetermined oxygen concentration difference between them. (b) the oxygen pump current generation source connected to the first oxygen pump section; and (c) the relationship between the reference generated electromotive force (E_0) corresponding to the oxygen concentration (O_2) of the calibration gas and the reference generation. Electromotive force (E_0)
The pump current (I_P_
(d) the electromotive force (V_S) of the oxygen concentration battery corresponding to the pump current (I_P_C) flowing through the second oxygen pump section when measuring the oxygen concentration of the measurement gas; The relationship is input, and from this relationship, the reference generated electromotive force (E_0) is determined by referring to the relationship between the pump current (I_P_C) and the reference generated electromotive force (E_0) stored in the storage circuit.
_0) and the electromotive force (V_S), and calculate the measured electromotive force (V_m) generated by the gas to be measured by dividing the reference generated electromotive force (E_0) and the electromotive force (
1. An oxygen concentration analyzer comprising: a calibration circuit that calculates an oxygen concentration (O_2) corresponding to a measured electromotive force (V_m) with reference to a relationship with V_S).