JPS6271841A - Oxygen analyzing method - Google Patents

Abstract

PURPOSE:To measure the amount of oxygen accurately even when a base current is not balanced by calculating previously an approximate current curve which connects smoothly two base currents to a time base before and after sample oxygen is introduced and discharged. CONSTITUTION:A constant DC voltage is applied to the solid-state electrolyte 20 in an oxygen pump 8 and the oxygen in carrier gas is discharged from a flow passage; and then oxygen from the sample is discharged similarly and the amount of the oxygen in the sample is measured from the quantity of electricity required for the discharging. The curve i3 which connect a current i1 which flows in an electrolyte 20 in the balanced state before the sample gas is introduced and a balanced base current i2 after the oxygen is discharged is calculated previously from the currents i1, a current i0 during sample gas analysis, and the balanced base current i2. Therefore, even when the base current is not balanced before and after the measurement of sample oxygen, an integral current value P is calculated from the approximate curve to measure the amount of oxygen accurately, thereby shortening the measurement time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in an oxygen analysis method using an oxygen analyzer using an electrochemical oxygen pump.

[Prior Art] Recently, the amount of oxygen contained in metals, alloys, combinations thereof, or half metals such as Hiren and Deluru has been reduced to 1.
Is it possible to measure absolute values with high precision? Ii L
/ type of oxygen analyzer has been developed (Shinya Otsuka, Zensaku Kozuka, -[ransacLion or[11
0J apan I n5titutc of
M eLals.

Vol-25, No, 9.639 pages ~ 648 Ci, 1
Lr issued September 984).

This M prefecture analysis'! A is -1-YariX? Circulate gas at 1℃
Surge:! An electrochemical oxygen pump using a solid electrolyte is interposed in one gas flow path, and by applying a constant DC voltage to the oxygen pump, 1 NOF of oxygen is discharged from the closed gas flow path to create a closed gas flow. This system is designed to maintain the oxygen partial pressure in the passage at a sufficiently low constant value.

Using this oxygen partial pressure state, oxygen analysis of the sample is performed as follows. First of all, alli t? Ki17s1 in front
[ in the agas is discharged by an oxygen pump, and the inside of the closed gas flow path is maintained at a low oxygen partial pressure per minute. At this time, in the oxygen pump J3, the amount of oxygen discharged to the outside of the closed gas flow path via the solid electrolyte and the amount of oxygen leaking from outside the thread have reached a nearly equilibrium state, and as shown in FIG. In the pump (2), a substantially constant base current 31 flows.

In state A, JFl is introduced into the closed gas flow path. The acid R released from the introduced sample (in the case of high-core samples, oxygen is rapidly released by dissolution) is carried by the carrier gas to the oxygen pump, where it is transferred to the closed gas stream. Ejected onto the street. At this time, the /A output acid resistance N:iJl output old fLj current 32, which is the phase of the current required for IJI output of the released oxygen from the test r1 and the base current, flows through the oxygen pump.

When +Jl of released oxygen is finished, the inside of the closed gas flow path is again maintained at a sufficiently low oxygen partial pressure state, and a substantially constant base current 33 flows through the oxygen pump again.

Then, from the discharge current 32 of released acid i, the base current 31
．． By subtracting the value of 33, and by finding the area of the shaded area 1ft34 in Figure 9, the amount of electricity of the Pa element pump required to produce one discharged oxygen can be found, and based on this amount of electricity, , the amount of oxygen in the sample is measured in absolute value quickly and at high viscosity.

[Problems to be Solved by the Invention] In the above measurement method, in order to analyze oxygen at high viscosity, the current required for exhausting the released oxygen from Test 21, that is, the current The shaded area 34 in the figure cannot be accurately calculated (J), but for that purpose, the base current 31
It is preferable that the base current 33 is a constant value current.

However, in order to make the oxygen supply price by the oxygen pump and the leakage of oxygen into the closed gas flow path almost perfectly balanced, and to make the base current 31.33 a nearly perfect constant current, it takes a lot of effort. II. There is a problem in that it has to last for 1 hour, which wastes time on the surveyor.

In addition, if there is air leakage into the closed gas flow path, the amount of H2O, etc. in the atmosphere may change gradually over time, so the amount of oxygen leaking into the closed gas flow path may change slowly over time. is likely to change. Then, the values of the base current 31 and the base current 33 in the region where the iJl output M tree suspension and the leaked oxygen are in a parallel state will be different, and the value of g in Fig. 9 will be different.
The measurement accuracy differs depending on how the l-ray region 34 is determined3. Among these, the vane chisel flow 31 and the base current 33 are averaged, and the (direct) is subtracted from the output current 32 of the released oxygen 111. ), there is a high possibility that the base city J≧ of the released oxygen is not required (Wa), and this may adversely affect the accuracy of determining the oxygen FAA in the sample.

The present invention makes it possible to measure high viscosity even when the surface angle Qk: L1 as described above does not reach a certain value at the base of the oxygen pump. End of measurement 1: The base current of l+ is different, and the objective is to accurately determine the electric motor required for exhausting the released oxygen from test n.1゜[To solve the problem] f stage] The oxygen analysis method of the present invention in accordance with this purpose circulates the V gas in a closed gas flow path in which an electrochemical oxygen pump using a solid electrolyte is interposed, and supplies a constant direct current to the oxygen pump. A voltage is applied 11 to keep the oxygen partial pressure at the interface between the 17 gas and the solid lightning 114 constant at all times, and first the oxygen 4 in the carrier 87 gas is closed using the acid water pump. The oxygen in the sample is discharged to the outside of the flow path to bring the oxygen partial pressure inside the closed gas flow path to a sufficiently low level. The released oxygen from the sample carried by the gas is discharged to the outside of the closed gas flow path by the oxygen pump to bring the inside of the closed gas flow path to a sufficiently low oxygen partial pressure again. By subtracting the base current flowing to the Pa element pump when the oxygen partial pressure is sufficiently low from the discharge oxygen current flowing to the oxygen pump during discharge to the outside of the wood empty gas flow path, In an oxygen analysis method in which the amount of electricity required to output oxygen outside the closed gas flow path (↑) and the amount of arousal in the sample from the electrical equipment is determined, the base current is calculated by r, η before introducing the sample. This method consists of obtaining an approximate current curve that smoothly connects the current curve with respect to the time axis of and the sentiment curve with respect to the time axis of the above-mentioned released oxygen +!1 exit/end port).

A smooth approximate current curve that connects base currents before and after the released oxygen current curve is approximated by, for example, a curve represented by -ALB. Here, i:
Current flowing through the oxygen pump t: time Δ, B: constant determined so that the He-Sumi flow connects smoothly.

[Effect]

In such an oxygen analysis method, the curve connecting the base currents before and after the emission of P&&IIL, which does not actually appear as an upstream waveform, is plotted at 51ξ as a smooth approximation curve using It will be done. This δ
;The smooth curve shows the lli! if the oxygen released from the sample is not exhausted during this period. 2 elements 78
It is obtained as a curve representing one transition state of the base current. Even if the base current before analysis of the released acid system from sample r1 is completely flat (P, equilibrium state), and the base current before analysis is completely flat (z1'), 1jl
Even if the characteristics of the curve have not reached I, the two characteristic curves are smoothly connected by a curve, so 1) the base current of J5 during the release of oxygen IJF! ! The Hiiragi state is approximated almost exactly.

For this accurately approximated base current of 1 h, the emission that actually appears as a waveform! Since the current is integrated into the 111 elemental discharge 1, the integral value can be accurately determined as the electric component required to discharge the released oxygen.

Therefore, even if you start measuring the amount of M water in a test film when the base current has not yet fully reached equilibrium, a sufficiently accurate measurement can be obtained.

Furthermore, even if the base current values before measurement and at the end of measurement 11.1 are different, the base current transition state between them is accurately approximated, so that the measured viscosity is improved.

(Embodiments) Preferred embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an oxygen analyzer for carrying out the method according to the invention.

FIG. 1 shows the overall configuration of the oxygen analyzer, and each directional control valve shows the state at the time of sample re-analysis.

In FIG. 1, the tIl path indicated by a thick line indicates the closed gas flow path 1 through which the gas A7 is circulated during the sample r1 solubility analysis. Each directional control valve 2.3.4 consists of a four-way valve in the wooden example, and for the acid system t6 analysis of Test H, the carrier gas in the closed gas flow path 1 is connected to the thick line as shown in the figure. Arrow A
Flowing in the direction of, the first 1 of the year! When replacing the gas in the gas flow path 1 with the carrier A70,000, it flows in the direction of the solid line arrow B, and when replacing the sample, the gas flows in the direction of the broken line arrow rDC.

The closed gas flow path 1 has a carrier gas circulation direction Δ during measurement.
As shown in Figure 5, the circulation pump 5 avoids circulating the gas.
, metals, alloys, or their compounds.

A sample introducing means 7 for introducing a sample 16 made of Y metal such as Aroha selenium and Deluru into the closed gas flow path 1, and a sample 671t.
An oxygen pump 8 is interposed in series to discharge the oxygen released from the gas and carried by the gas to the outside of the gas flow path 1.

On the upstream side of the circulation pump 5, a flow rate: i]9 is provided that can set the diversion (flow rate) of the ↑V clear gas circulated by the circulation pump 5. Also, acidhobonbu 8
and the circulation pump 5 (Oh, you're a demon! I'm going to put Bacchus in the empty gas flow path 1 ↑ Auction 11 swords) 9 people 10 hours <
Continuing to cough, 3 TeJ, 11 filters, 2 direction switches
The carry towing 7 gas is cammed through the
Ru. This closure connects flow path 1 to 1-・sui! When replacing with gas, the directional control valve 2.3.4 is switched as shown by arrow 3, and the vacuum suction port 12 is connected to the end of the path 113 to supply carrier gas. The gas in the closed gas flow path 1 that has been expelled by the pump is discharged to the outside of the system via the filter 13 and the suction pump 14.

The sample introduction means 7 is formed in the shape of a container that can be sealed tightly, and the sample 6 is placed in the device and rotated for one trial.
Fi (sample receptacle 15 is installed to avoid dropping 3 downward)
I'm bored. A sample melting furnace 16 is provided below the sample introduction means 7. The sample melting furnace 16 has a sample receiving [
The sample 6 dropped from the pipe 15 is melted by heating with a heating device 7, and the oxygen is released from the sample C, which is placed on the flow of xeryl gas.

However, in the case of materials such as gallium, which have a melting point close to room temperature, the measurement may fail even without heating. 1711 Heat necking 17 and sample interrogator means 7.

In addition to suppressing heat transfer from the heating device 17 side to the sample introduction means 7, there is also a device between the heating device 17 side and the sample introduction device 7, which condenses metal vapor etc. from the sample melting furnace 16 and prevents it from flowing downstream. 111 cooling means 18 are provided. Cooling means 18: Depending on the shell cooling requirement, use a cooling fan as shown in the figure or water cooling. ,) Ji1? Grooves are used as a means of natural heat dissipation through jackets and fins.

The oxygen pump 8 is equipped with a heating furnace 19 and a cylindrical solid electrolyte 120 housed in the heating furnace 19 as shown in FIG. (j,
Since zirconia is solid-dissolved with oxides such as calcia, magnesia, oxide, and T as a stabilizer, it has acid-based oxides. Oxides of the two types of oxides, motos and molasses, may be dissolved in solid solution.

It is also possible to use a solid electrolyte formed by dissolving itria in thoria. A rectifying tube 21 made of a heat-resistant material such as silica and formed into a capsule shape with a reduced pressure inside is placed inside the solid state solution 20.

Porous electrodes 22 are provided on both the inner and outer surfaces of the solid "lIf solute 20.
．． 23 are provided. A portion of the inner electrode 22 extends toward both ends of the solid electrolyte 20 in the longitudinal direction, and further extends to a portion of the outer surface of the solid electrolyte t'x 20 by folding back its end. These porous electrodes 22 and 23 are made by applying platinum paste or the like to the surface of the solid electrolyte 20.
It is formed by burning.

Lead wires 24 and 25 are connected to the electric wire 22, and lead wires 26 and 27 are connected to the electrode 23, respectively. 1 set of glue part I! ! Between 24 and 26 is a variable free current power supply (
f) (not shown) is connected, and an ammeter (not shown) is connected in series with the variable DC power supply. On the other hand, a voltmeter (shown in the figure) is connected between the lead wires 25 and 27.

The function of this oxygen pump 8 is roughly as follows. When a constant DC voltage is applied to both sides of the solid electrolyte 20 via the lead wires 24 and 26, an electrochemical bodency is generated in the solid 441Ui electrolyte 20 from one side to the other. (!1 From inside gas flow path 1)
The li thread is discharged. By applying a constant DC voltage to the measurement surface, oxygen is discharged from the gas 17 to the outside of the closed gas flow path 1, but eventually due to oxygen leaking from the outside and acid released from the solid electrolyte 20 itself. When the equilibrium state is near <<K, the current i flowing through the lead wires 24 and 26 has a sufficiently low base current value. In this state, the sample F16 is introduced, and e-element released from the sample 6 is carried to the oxygen pump E3 and discharged to the outside of the closed gas flow path 1. At this time, the current iG rises by 7, and once the oxygen has been output 1), it returns to the base current again.

By detecting this current change using the current at and determining the 1 u of electricity required to discharge oxygen, it is possible to determine the amount of oxygen in the sample 6 in relation to its quality. In addition, lead wire 2
The voltmeter connected to 5.27 is designed to constantly read the electromotive force of the oxygen pump 8.

J3, -V-described test II
``Inert gas such as argon gas is used as the electric/rear gas, and it contains a certain amount of hydrogen as a reducing gas.
It is desirable to use X7 gas. By containing hydrogen in this manner, the oxygen in the sample reacts with hydrogen and is released as a stable HzO gas. This 1)2
The 0 gas is carried to the oxygen pump 8 and is electrochemically decomposed on the inner surface of the solid electrolyte 2Q to become hydrogen again, and the oxygen generated at that time is transferred to the outside of the closed gas flow path 1 by the function of the oxygen pump 8 mentioned above. be discharged.

[The method of the present invention is carried out as follows using an apparatus having the configuration as described above.

First, the sample 6 is placed in the closed gas flow path 1 or in the sample melting furnace 16.
Before installing the oxygen pump 8, as shown in Figure 3,
The data of the base current 11 flowing through the 11.1 axis is collected for a period of 11.1, and the characteristic curve of the base current 11 with respect to the 115 axis [1! ! It is input in the i position.

The sample 6 is introduced into the second data collection trench through the sample melting furnace 16, and oxygen is released from the sample 6bs into the closed gas flow path 1. The released oxygen is carried by the gas to the oxygen pump 8, and is discharged out of the closed gas flow path 1 by the oxygen pump 8. During this discharge, the current 1 rises as shown in FIG. 4, reaches a peak as shown in FIG. 5, and then gradually falls to a current waveform i0. and,
This released oxygen exhaust current 10 eventually becomes a current 12 close to an equilibrium state. Released oxygen IJ from current 11 to 12
The I output current iG is collected as waveform data.

Next, the activation curve of the base current 12 during released oxygen υ[output r is collected for a certain period of time.

Then, as shown in FIG. 6, a lightning current curve i3 is obtained by clearly connecting the characteristic curve of the base current 11 and the characteristic curve of the base current I2.

This 13 is! For example, 1=to[B is calculated by the formula, constant Δ, B is 1.1tijl, and the current curve i3 is! 1. It is determined so that it smoothly connects with the characteristic curve of i2. Here, if E3=1, the approximate current curve i31 is determined as a straight line.

This approximate rh current curve 3 is actually a current waveform of −C
This is required as an imaginary characteristic curve that does not appear, but if i 1. This is obtained as a transition special curve of the base current that would have been obtained if the iJI output of released oxygen had not occurred between i and 2. In other words, it is determined as a current component that does not contribute to the emission from the sample 6.

With respect to the approximate current curve 1 obtained in this manner, the discharged oxygen current 10 is integrated, and the area of the shaded region P shown in FIG. 5 is obtained. This area does not represent the amount of electricity required for iJI of released oxygen from the sample 6. The amount of oxygen in the sample 5 is analyzed from this amount of electricity.

Since the approximate current curve 13 is determined so as to smoothly connect with the characteristic curves 11 and 12, the transition of the base current from 11 to 12 can be grasped in an accurate state close to the actual transition. Therefore, as shown in FIGS. 7 and 8, for example, the base current phase 1 immediately before S when measuring released oxygen is
Even if 1 has not yet reached a sufficient equilibrium state,
Alternatively, if the values of the base currents i + and i 2 before and after the measurement are considerably different, the transition state of the base current between them is approximately accurately approximated by the approximate curve 13, and the shaded area P a , ! ] The amount of acid released from b (i, IJ+, t, ω, required for release) can be accurately determined.

[Effects of the Invention] As explained above, according to the oxygen analysis method of the present invention, the base current in the oxygen pump during exhaustion of released oxygen from the sample, and the current curves before and after the measurement;
Accurately approximate the approximate current curve connected to this approximate current! Since the amount of electricity required to output the released oxygen IJI was determined from the difference between line III and the current waveform during actual discharge of released oxygen, the base current of the oxygen pump before and after the measurement was sufficient to ensure that the IL equilibrium was open. Accurate measurement can be performed even when the measurement time is not available, and the measurement time can be significantly shortened.

In addition, leakage into the closed gas flow path may cause changes in the properties of the atmosphere.
? Therefore, even if there is a difference between the upstream level of the base before and after the measurement, it is possible to accurately determine the electricity t required to discharge the PIi elements released from the sample, and it is possible to improve measurement accuracy. The effect is also 1! I get caught.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a one-time chemical analyzer for carrying out a method according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the oxygen pump section of the device shown in FIG. 1, and FIG. Figure 4 shows the current characteristics of the oxygen pump before the sample is introduced. Figure 4 shows the current characteristics of the oxygen pump immediately after the oxygen released from the sample. 2
Figures 7 and 83 are the base, and the measuring state of the lifting platform where the current has not reached the equilibrium state. Figure 9 shows the measurement state when the base current has sufficiently reached an equilibrium state, and is a current characteristic diagram of 1 oxygen 1 gun. It is. 1...Closed gas flow path 2, J゛1.4...Directional switching valve 5...Circulation pump 6...-Sample 7... Sample introduction stage 1 8...Cargo pump 9...Flow h1 Total 10...Kisseri A7 Gas inlet 12...
・Reduced It suction l" 16... Sample melting furnace 19... Heating furnace 20... Solid 7iH solution v1 21... Rectifier tube 22.23... ... Electrode 24.25.26.27 ... Lead wire 1 ...
...Oxygen pump current il, i2... Base current 10... Current when ejecting M element i3... Approximate current curve Fig. 2 Fig. 9 Fig. 7 Figure 8

Claims (1)

[Claims] (1) A carrier gas is circulated in a closed gas flow path in which an electrochemical oxygen pump using a solid electrolyte is interposed, and a constant DC voltage is applied to the oxygen pump to form an interface between the carrier gas and the solid electrolyte. The oxygen partial pressure in the carrier gas is kept constant at all times, and the oxygen in the carrier gas is first discharged to the outside of the closed gas flow path by the oxygen pump to bring the inside of the closed gas flow path to a sufficiently low oxygen partial pressure, and then the oxygen partial pressure in the closed gas flow path is A sample is introduced into the closed gas flow path to release the oxygen in the sample into the closed gas flow path, and the released oxygen from the sample carried by the carrier gas is discharged to the outside of the closed gas flow path by the oxygen pump to create a closed gas flow path. From the current flowing through the oxygen pump during discharge of the released oxygen to the outside of the closed gas flow path,
By subtracting the base current flowing through the oxygen pump when the oxygen partial pressure is sufficiently low, the amount of electricity required to discharge the released oxygen to the outside of the closed gas flow path is determined, and from this amount of electricity, the amount of oxygen in the sample is calculated. In the method for oxygen analysis, the base current is determined as an approximate current curve that smoothly connects a current curve with respect to the time axis before the introduction of the sample and a current curve with respect to the time axis at the end of the released oxygen discharge. Oxygen analysis method.