JP2015049220A - Magnetic oxygen analysis method and magnetic oxygen analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic oxygen analyzer that is insensitive to flow fluctuation of an auxiliary gas or a measurement gas, while allowing reduction in device cost.SOLUTION: The magnetic oxygen analyzer comprises: a bypass flow passage 11 for communicating an auxiliary gas flow passage 9 on a first auxiliary gas flow inlet 6 side and an auxiliary gas flow passage 10 on a second auxiliary gas flow inlet 7 side; a buffer flow passage 24 provided by expanding an intermediate portion of the bypass flow passage; a first flow sensor 21 arranged on the bypass flow passage closer to the first auxiliary gas flow inlet side from the buffer flow passage; a second flow sensor 22 arranged on the bypass flow passage closer to the second auxiliary gas flow inlet side from the buffer flow passage. An oxygen concentration calculation unit 23 calculates an oxygen concentration SC contained in a measurement gas, based on a difference between a first flow SA of an auxiliary gas flowing from the first auxiliary gas flow inlet detected by the first flow sensor and a second flow SB of an auxiliary gas, detected by the second flow sensor, flowing through the buffer flow passage into the bypass flow passage on the second auxiliary gas flow inlet side.

Description

  The present invention relates to a magnetic oxygen analysis method and a magnetic oxygen analyzer.

The measurement principle of the magnetic oxygen analyzer will be described with reference to FIGS. 4A to 4C (see, for example, Patent Document 1).
FIG. 5A shows the relationship between oxygen molecules and a magnetic field when a means (magnet) for generating a magnetic field is arranged in a gas containing oxygen. As shown in FIG. 5B, a force that attracts oxygen acts on the magnetic field that is strong and changes in strength (the end of the magnetic pole that is a non-uniform magnetic field). The right force and the left force are pressed against each other and balanced, and oxygen molecules are attracted by the influence of the magnetic field and move into the magnetic field (magnet gap). As a result, as shown in FIG. 5C, the pressure (concentration) of the attracted oxygen is higher in the magnetic field than in the magnetic field.

An apparatus shown in FIG. 6 is known as a magnetic oxygen analyzer that employs the measurement principle described above. This magnetic oxygen analyzer detects a concentration of oxygen contained in a measurement gas using a signal from a sample cell 1 having a flow path for flowing the measurement gas and a flow sensor 12 installed in the sample cell 1. Circuit 2.
The sample cell 1 includes a sample channel 3 having a rectangular cross section, a measurement gas inlet 4 provided in communication with one end of the sample channel 3 in the axial direction, and the other end in the axial direction of the sample channel 3 A measurement gas outlet port 5 provided in communication with the sample gas passage and a sample channel 3 on the side of the measurement gas outlet port 5 and provided opposite to each other in a radial direction perpendicular to the axial direction of the sample channel 3. The auxiliary gas flowing into the first auxiliary gas inlet 6 and the second auxiliary gas inlet 7 and the auxiliary gas supply channel 8 is transferred from the first auxiliary gas inlet 6 and the second auxiliary gas inlet 7 to the sample channel 3. A pole piece that forms a region of the magnetic field Mf in the vicinity of the first auxiliary gas branch channel 9 and the second auxiliary gas branch channel 10 supplied at the same flow rate and the first auxiliary gas inlet 6 of the sample channel 3 communicate with each other. ((Not shown), the first auxiliary gas branch channel 9 and the second auxiliary gas component) A bypass passage 11 communicating with the passage 10, and a.

Further, a flow rate sensor 12 is disposed at an intermediate position of the bypass flow path 11, and the detection circuit 2 is connected to the flow rate sensor 12. The detection circuit 2 detects the oxygen concentration contained in the measurement gas by receiving and amplifying the signal from the flow sensor 12.
In the magnetic oxygen analyzer having the above configuration, the measurement gas introduced from the measurement gas inlet 4 of the sample cell 1 flows toward the measurement gas outlet 5. In addition, the auxiliary gas supplied from the auxiliary gas supply flow path 8 is divided into the first auxiliary gas branch flow path 9 and the second auxiliary gas branch flow path 10, and the first auxiliary gas inlet 6 and the second auxiliary gas flow. It flows into the sample channel 3 from the inlet 7, merges with the measurement gas, and flows to the measurement gas outlet 5. Further, a part of the auxiliary gas that is branched from the auxiliary gas supply flow path 8 to the first auxiliary gas branch flow path 9 and the second auxiliary gas branch flow path 10 is a bypass flow path that is connected to the first auxiliary gas branch flow path 9. 11 flows from the bypass flow path 11 connected to the second auxiliary gas branch flow path 10 toward the flow sensor 12.

  And when oxygen molecules are not contained in the measurement gas, even if the magnetic field Mf is applied in the vicinity of the first auxiliary gas inlet 6 of the sample flow path 3, oxygen molecules are not attracted, The pressure does not increase. Thereby, the fluid resistance when the auxiliary gas flows out from each of the first auxiliary gas branch flow path 9 and the second auxiliary gas branch flow path 10 to the sample flow path 3 becomes the same, and the first auxiliary gas branch flow path 9 The flow rate of the auxiliary gas passing through the flow rate sensor 12 in the bypass flow path 11 is the same as the flow rate of the auxiliary gas passing through the flow rate sensor 12 in the bypass flow path 11 from the second auxiliary gas branch flow path 10. Thereby, the signal of the flow sensor 12 is not obtained, and the detection circuit 2 does not detect the oxygen concentration.

  On the other hand, when oxygen molecules are contained in the measurement gas, when the magnetic field Mf is applied in the vicinity of the first auxiliary gas inlet 6 of the sample flow path 3, the oxygen molecules are attracted to that portion (see FIG. 5 (C)), the pressure increases due to the cohesive pressure of oxygen. Therefore, the fluid resistance when the auxiliary gas flows out from the first auxiliary gas branch flow path 9 to the sample flow path 3 increases, and the outflow amount decreases. On the contrary, in the vicinity of the second auxiliary gas inlet 7 of the sample flow path 3, the magnetic resistance Mf is not applied since the magnetic field Mf is not applied, so that the fluid resistance does not increase. Outflow increases.

  Thereby, the auxiliary gas is the first auxiliary gas at the point P0 (hereinafter referred to as the branch point P0) where the auxiliary gas supply flow path 8 branches to the first auxiliary gas branch flow path 9 and the second auxiliary gas branch flow path 10. The diversion ratio at the time of branching to the branch channel 9 and the second auxiliary gas branch channel 10 changes, and the flow rate of the auxiliary gas from the first auxiliary gas branch channel 9 via the flow sensor 12 in the bypass channel 11 A difference occurs in the flow rate of the auxiliary gas passing through the flow rate sensor 12 in the bypass flow channel 11 from the second auxiliary gas branch flow channel 10, and the flow rate sensor 12 obtains a signal of change in the flow rate of the auxiliary gas. Detects the oxygen concentration of the measurement gas.

FIG. 3 of JP 2004-325098 A

By the way, the conventional magnetic oxygen analyzer described above cannot accurately measure the oxygen concentration in the measurement gas when the flow rate of the auxiliary gas or the measurement gas fluctuates due to vibrations received from surrounding plants. There is.
That is, when oxygen molecules are contained in the measurement gas, the pressure increased by the coagulation pressure of oxygen passes from the first auxiliary gas branch channel 9 and the bypass channel 11 to the flow rate sensor 12, and the flow rate sensor 12 It converts into an electric signal according to the pressure. Here, when a flow rate fluctuation occurs in the auxiliary gas supplied from the auxiliary gas supply flow path 8, a pulsating flow due to the flow fluctuation of the auxiliary gas is generated in the bypass flow path 11, and this pulsating flow is superimposed on the electrical signal of the flow sensor. This becomes a noise component, and the oxygen concentration in the measurement gas cannot be measured accurately.

Similarly to the flow rate variation of the auxiliary gas, when the flow rate of the measurement gas supplied from the measurement gas introduction port 4 varies, a pulsating flow due to the flow rate variation of the measurement gas occurs in the bypass channel 11, and the pulse The flow becomes a noise component in a form superimposed on the electric signal of the flow sensor.
Therefore, in order to keep the flow rate of auxiliary gas or measurement gas constant, a precise pressure control valve is connected to the supply side of auxiliary gas and measurement gas, or to avoid temperature fluctuations of the pressure control valve and each flow path. Measures to reduce fluctuations in the flow rates of the auxiliary gas and measurement gas, such as placing necessary equipment in a thermostatic bath, can be considered, but such measures are problematic in terms of increasing mechanisms and parts and increasing costs. There is.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a magnetic oxygen analyzer and a magnetic oxygen analyzer that are resistant to fluctuations in the flow rate of auxiliary gas or measurement gas while reducing the cost of the apparatus. It is said.

  In order to achieve the above object, a magnetic oxygen analysis method according to an aspect of the present invention includes a sample channel, a measurement gas inlet and a measurement gas outlet formed at both ends of the sample channel, and the measurement gas outlet. A first auxiliary gas inlet and a second auxiliary gas inlet provided opposite to each other on the side of the sample flow path, and an auxiliary gas flow path connected to the first and second auxiliary gas inlets. And detecting a change in the flow rate of the auxiliary gas channel caused by supplying the auxiliary gas from an intermediate position of the auxiliary gas channel and applying a magnetic field to the sample channel near the first auxiliary gas inlet. Thus, in the magnetic oxygen analysis method for calculating the oxygen concentration contained in the measurement gas, the auxiliary gas flow path on the first auxiliary gas inlet side and the auxiliary gas flow on the second auxiliary gas inlet side The road and the A buffer flow path that is enlarged in flow path is provided at an intermediate position of the bypass flow path, and the auxiliary gas flowing from the buffer flow path to the bypass flow path on the first auxiliary gas inlet side is provided. The first flow rate is detected, the second flow rate of the auxiliary gas that passes through the buffer flow channel and flows into the bypass flow channel on the second auxiliary gas inlet side is detected, and the detected first flow rate and the second flow rate are detected. Based on the difference in flow rate, the oxygen concentration contained in the measurement gas was calculated.

  According to the magnetic oxygen analysis method according to one aspect of the present invention, even if the flow rate fluctuation occurs in the measurement gas or auxiliary gas, the flow rate fluctuation occurs in the measurement gas or auxiliary gas and the measurement gas or auxiliary gas. Since the concentration of the measurement gas is calculated based on the difference between the second flow rate, which is a correction value obtained by adding the noise component due to the pulsating flow and the flow rate associated with the pressure change, the flow rate of the measurement gas or auxiliary gas It is possible to measure the oxygen concentration of the measurement gas with high accuracy by removing the influence of fluctuation.

In the magnetic oxygen analysis method according to one aspect of the invention, the position where the first flow rate and the second flow rate are detected is the bypass flow channel that is equidistant from the buffer flow channel.
According to the magnetic oxygen analysis method according to one aspect of the present invention, it is possible to prevent the influence of the pipe viscosity and temperature distribution of the bypass flow path from being biased.
The magnetic oxygen analysis method according to one aspect of the invention uses a two-wire thermal flow meter for detection of the first flow rate and the second flow rate.
According to the magnetic oxygen analysis method according to one aspect of the present invention, the measurement value and the correction value can be detected with high accuracy without being affected by the ambient temperature fluctuation.
In the magnetic oxygen analysis method according to one aspect of the invention, the auxiliary gas is supplied simultaneously to an intermediate position of the auxiliary gas channel and the buffer channel.
According to the magnetic oxygen analysis method according to one aspect of the present invention, the start time of the measurement gas oxygen analysis can be greatly shortened.

  The magnetic oxygen analyzer according to one aspect of the invention includes a sample flow path, a measurement gas inlet and a measurement gas outlet formed at both ends of the sample flow path, and the sample flow path on the measurement gas outlet side. A first auxiliary gas inlet and a second auxiliary gas inlet provided opposite to each other; and an auxiliary gas channel connected to the first and second auxiliary gas inlets, the auxiliary gas channel The auxiliary gas is supplied from an intermediate position of the first auxiliary gas channel, and a change in the flow rate of the auxiliary gas channel caused by applying a magnetic field to the sample channel near the first auxiliary gas inlet is detected. In the magnetic oxygen analyzer for calculating the concentration of oxygen contained therein, a bypass flow path communicating the auxiliary gas flow path on the first auxiliary gas inlet side and the auxiliary gas flow path on the second auxiliary gas inlet side; , This bipa A buffer channel provided by enlarging the channel at an intermediate position of the channel, a first flow rate sensor disposed in the bypass channel on the first auxiliary gas inlet side from the buffer channel, and the buffer channel A second flow rate sensor disposed in a bypass flow path on the second auxiliary gas inlet side, a first flow rate of auxiliary gas flowing from the first auxiliary gas inlet detected by the first flow rate sensor, Based on the difference between the second flow rate of the auxiliary gas passing through the buffer flow path detected by the second flow rate sensor and flowing into the bypass flow path on the second auxiliary gas inflow side, the oxygen concentration contained in the measurement gas is determined. An oxygen concentration calculation unit for calculating.

  According to the magnetic oxygen analyzer according to one aspect of the present invention, it is possible to provide an apparatus for measuring the oxygen concentration of the measurement gas with high accuracy by removing the influence of the flow rate fluctuation of the measurement gas or the auxiliary gas. In addition, no mechanism or device for keeping the flow rate of the measurement gas or auxiliary gas constant (suppressing flow rate fluctuations) is used, and the device cost can be reduced.

In the magnetic oxygen analyzer according to one aspect of the invention, the first flow rate sensor and the second flow rate sensor are disposed in the bypass flow path at a position equidistant from the buffer flow path.
According to the magnetic oxygen analyzer according to one aspect of the present invention, it is possible to prevent the influence of the pipe viscosity, temperature distribution, and the like of the bypass flow path from being biased.
In the magnetic oxygen analyzer according to one aspect of the invention, the first flow sensor and the second flow sensor are two-wire thermal flow meters.
According to the magnetic oxygen analyzer according to one aspect of the present invention, the measurement value and the correction value can be detected with high accuracy with little influence by the ambient temperature fluctuation.
The magnetic oxygen analyzer according to an aspect of the invention includes an auxiliary gas supply unit that supplies the auxiliary gas to the intermediate position of the auxiliary gas channel and the buffer channel at the same time.
According to the magnetic oxygen analyzer according to one aspect of the present invention, the time from the start of the apparatus to the start of the measurement gas oxygen analysis can be greatly shortened.

According to the magnetic oxygen analysis method of the present invention, even when the flow fluctuation occurs in the measurement gas or the auxiliary gas, the flow fluctuation occurs in the first flow rate as the measurement value and the measurement gas or the auxiliary gas. The concentration of the measurement gas is calculated based on the difference between the second flow rate, which is a correction value that combines the noise component due to the pulsating flow and the flow rate associated with the pressure change. The influence can be removed and the oxygen concentration of the measurement gas can be measured with high accuracy.
In addition, according to the magnetic oxygen analyzer of the present invention, it is possible to measure the oxygen concentration of the measurement gas with high accuracy by removing the influence of the flow rate variation of the measurement gas or auxiliary gas, and to measure the measurement gas or auxiliary gas. The mechanism and the device for suppressing the flow rate fluctuations are not used, and the device cost can be reduced.

1 is a schematic configuration diagram showing a magnetic oxygen analyzer according to a first embodiment of the present invention. It is a flowchart which shows operation | movement of the oxygen concentration calculating part which comprises the magnetic type oxygen analyzer of 1st Embodiment which concerns on this invention. It is a figure for demonstrating the method for which the magnetic oxygen analyzer of 1st Embodiment which concerns on this invention analyzes the oxygen concentration of the measurement gas which flow volume fluctuation | variation generate | occur | produced and the oxygen molecule is contained. It is a schematic block diagram which shows the magnetic-type oxygen analyzer of 2nd Embodiment which concerns on this invention. It is a figure which shows the measurement principle of a magnetic oxygen analyzer. It is a figure which shows the conventional magnetic oxygen analyzer.

DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. The same components as those of the magnetic oxygen analyzer shown in FIG.
FIG. 1 shows a magnetic oxygen analyzer according to a first embodiment of the present invention. A sample cell 20 and a first flow sensor 21 and a second flow sensor 22 installed in the sample cell 20 are shown in FIG. It comprises a detection circuit 23 for detecting the oxygen concentration contained in the measurement gas by a signal.

  The sample cell 20 includes a sample channel 3 having a rectangular cross section, a measurement gas inlet 4 provided in communication with one end of the sample channel 3 in the axial direction, and the other end in the axial direction of the sample channel 3 A measurement gas outlet port 5 provided in communication with the sample gas passage and a sample channel 3 on the side of the measurement gas outlet port 5 and provided opposite to each other in a radial direction perpendicular to the axial direction of the sample channel 3. The auxiliary gas flowing into the first auxiliary gas inlet 6 and the second auxiliary gas inlet 7 and the auxiliary gas supply channel 8 is transferred from the first auxiliary gas inlet 6 and the second auxiliary gas inlet 7 to the sample channel 3. A pole piece that forms a region of the magnetic field Mf in the vicinity of the first auxiliary gas branch channel 9 and the second auxiliary gas branch channel 10 supplied at the same flow rate and the first auxiliary gas inlet 6 of the sample channel 3 communicate with each other. ((Not shown), the first auxiliary gas branch channel 9 and the second auxiliary gas A bypass passage 11 communicating with the 岐流 path 10, and a.

In the sample cell 20 of the present embodiment, a buffer flow path 24 in which the flow path is enlarged is formed at an intermediate position of the bypass flow path 11. A first flow rate sensor 21 is disposed in the bypass flow path 11 on the first auxiliary gas branch flow path 9 side from the buffer flow path 24, and the bypass flow path 11 on the second auxiliary gas branch flow path 10 side from the buffer flow path 24. The second flow rate sensor 22 is disposed, and the first flow rate sensor 21 and the second flow rate sensor 22 are disposed at a position equidistant from the buffer flow path 24.
The first flow sensor 21 and the second flow sensor 22 are two-wire thermal flow meters, and are connected to the detection circuit 23.

The detection circuit 23 includes a first detection circuit 23a connected to the first flow rate sensor 21, a second detection circuit 23b connected to the second flow rate sensor 22, and the first detection circuit 23a and the second detection circuit 23b. And a differential amplifier 23c connected to the.
FIG. 2 shows a flowchart of a method for calculating the measurement gas concentration performed by the detection circuit 23. In step ST1, the measurement signal SA detected by the first flow sensor 21 is obtained by the first detection circuit 23a. Next, in step ST2, the correction signal SB detected by the second flow sensor 22 by the second detection circuit 23b is obtained. Next, in step ST3, the differential amplifier 23c calculates the difference between the measurement signal SA and the correction signal SB to obtain the concentration signal SC of the measurement gas.

  In the magnetic oxygen analyzer having the above configuration, the measurement gas introduced from the measurement gas inlet 4 of the sample cell 20 flows toward the measurement gas outlet 5. In addition, the auxiliary gas supplied from the auxiliary gas supply flow path 8 is divided into the first auxiliary gas branch flow path 9 and the second auxiliary gas branch flow path 10, and the first auxiliary gas inlet 6 and the second auxiliary gas flow. It flows into the sample channel 3 from the inlet 7, merges with the measurement gas, and flows to the measurement gas outlet 5. Further, a part of the auxiliary gas that is branched from the auxiliary gas supply flow path 8 to the first auxiliary gas branch flow path 9 and the second auxiliary gas branch flow path 10 is a bypass flow path that is connected to the first auxiliary gas branch flow path 9. 11 flows toward the first flow rate sensor 21 and flows from the bypass flow path 11 connected to the second auxiliary gas branch flow path 10 toward the second flow rate sensor 22.

Next, the operation of the magnetic oxygen analyzer of this embodiment will be described.
In the case where oxygen molecules are not contained in the measurement gas supplied from the measurement gas inlet 4, even if the magnetic field Mf is applied in the vicinity of the first auxiliary gas inlet 6 of the sample flow path 3, the oxygen molecules are not generated. It is not attracted and the pressure in that part does not increase. Thereby, the fluid resistance when the auxiliary gas flows out from each of the first auxiliary gas branch flow path 9 and the second auxiliary gas branch flow path 10 to the sample flow path 3 becomes the same, and the first auxiliary gas branch flow path 9 From the second auxiliary gas branch flow path 10 to the bypass flow path 11 becomes the same amount. In this case, the detection circuit 23 obtains the measurement signal SA detected by the first flow sensor 21 by the first detection circuit 23a (step ST1 in FIG. 2), and is detected by the second flow sensor 22 by the second detection circuit 23b. A correction signal SB (SA = SB) is obtained (step ST2 in FIG. 2). Then, the differential amplifier 23c calculates the difference between the measurement signal SA and the correction signal SB to obtain a measurement gas concentration signal SC (step ST3 in FIG. 2). In this case, a calculation result is obtained in which the concentration signal SC of the measurement gas is zero (0).

Next, a case where the measurement gas is supplied from the measurement gas inlet 4 while generating a flow rate variation and oxygen molecules are contained in the measurement gas will be described with reference to FIG.
When the magnetic field Mf is applied in the vicinity of the first auxiliary gas inlet 6 of the sample channel 3 communicating, oxygen molecules are attracted to that portion (see FIG. 5C), and the pressure rises due to the aggregation pressure of oxygen. To do. Therefore, the fluid resistance when the auxiliary gas flows out from the first auxiliary gas branch flow path 9 to the sample flow path 3 increases, the outflow amount decreases, and the pressure of the auxiliary gas in the first auxiliary gas branch flow path 9 becomes P. To rise.

  Since the flow rate variation occurs in the measurement gas, a pulsating flow due to the flow rate variation of the measurement gas occurs in the bypass channel 11, and the first flow rate sensor 21 detects the noise component Sn due to the pulsating flow as the measurement signal SA. Further, the first flow sensor 21 detects the flow rate Qp associated with the pressure P and the flow rate Qf associated with the pressure change of the flow rate variation of the measurement gas as a measurement signal SA in addition to the noise component Sn1 (SA = Sn + Qp + Qf: FIG. Step ST1 of 2).

Then, the auxiliary gas that has passed through the first flow rate sensor 21 passes through the buffer flow path 24, whereby the flow rate Qp associated with the pressure P is attenuated, and the second flow rate sensor 22 has a noise component Sn due to pulsation, The flow rate Qf accompanying the pressure change of the flow rate fluctuation of the measurement gas is detected as the correction signal SB (SB = Sn + Qf: step ST2 in FIG. 2). Then, the differential amplifier 23c calculates a difference between the measurement signal SA and the correction signal SB, and obtains a measurement gas concentration signal SC represented by the following equation (1) (step ST3 in FIG. 2).
SC = SA-AB = (Sn1 + Qp + Qf)-(Sn1 + Qf) = QP (1)
As is clear from the equation (1), the magnetic oxygen analyzer of the present embodiment has the noise component Sn due to the pulsation of the flow rate fluctuation of the measurement gas and the flow rate fluctuation even if the flow rate fluctuation occurs in the measurement gas. A concentration signal SC of the measurement gas excluding the flow rate Qf accompanying the pressure change is calculated.

In addition, although FIG. 3 demonstrated the case where flow volume fluctuation | variation generate | occur | produced in measurement gas, when flow volume fluctuation | variation has generate | occur | produced in the auxiliary gas supplied from the auxiliary gas supply path 8, the flow fluctuation of auxiliary gas is also demonstrated. The concentration signal SC of the measurement gas is calculated by removing the noise component due to the pulsating flow and the flow rate accompanying the pressure change of the auxiliary gas flow rate variation.
Here, the measurement gas inlet according to the present invention corresponds to the measurement gas inlet 4, the measurement gas outlet according to the present invention corresponds to the measurement gas outlet 5, and the auxiliary gas flow path according to the present invention is the first auxiliary gas. Corresponding to the branch flow path 9 and the second auxiliary gas branch flow path 10, the first flow rate according to the present invention corresponds to the flow rate detected by the first flow rate sensor 21, and the second flow rate according to the present invention is the second flow rate. Corresponding to the flow rate detected by the flow sensor 22, the oxygen concentration calculation unit according to the present invention corresponds to the detection circuit 23.

Next, the effect of this embodiment is demonstrated.
According to this embodiment, even when the flow rate of the measurement gas or the auxiliary gas is varied, the first auxiliary gas branching channel 9 side is closer to the buffer channel 24 provided at the intermediate position of the bypass channel 11. 1 The flow rate sensor 21 measures the flow rate (referred to as measurement value) of the auxiliary gas, and the second flow rate sensor 22 changes the flow rate of the measurement gas or auxiliary gas on the second auxiliary gas branch flow channel 10 side from the buffer flow channel 24. The noise component due to the generation of pulsating flow and the flow rate (hereinafter referred to as a correction value) accompanying the pressure change are measured, and the detection circuit 23 calculates the concentration of the measurement gas based on the difference between the correction value and the correction value. Therefore, it is possible to measure the oxygen concentration of the measurement gas with high accuracy by removing the influence of the flow rate variation of the measurement gas or auxiliary gas.

In addition, according to the magnetic oxygen analysis method of the present embodiment, the measured value and the correction value are measured in the bypass channel 11 at a position equidistant from the buffer channel 24. Therefore, the pipe viscosity and temperature distribution of the bypass channel are measured. It is possible to measure the oxygen concentration of the measurement gas with higher accuracy.
Further, since the first flow sensor 21 and the second flow sensor 22 use a two-wire thermal flow meter, there is little influence due to ambient temperature fluctuations, and the measurement value and the correction value can be detected with high accuracy.
Further, the magnetic oxygen analyzer of the present embodiment does not use a mechanism or device for keeping the flow rate of the measurement gas or the auxiliary gas constant (suppressing the flow rate fluctuation), and also reduces the device cost. be able to.

Next, what is shown in FIG. 4 shows a magnetic oxygen analyzer according to a second embodiment of the present invention.
In the magnetic oxygen analyzer of the second embodiment, a buffer dedicated channel 25 is provided between the auxiliary gas supply channel 8 and the buffer channel 24, and the auxiliary gas supplied from the auxiliary gas supply channel 8. However, it flows directly into the buffer flow path 24 without bypassing the other flow paths.
In this embodiment, when the apparatus is activated, the supply of the auxiliary gas from the auxiliary gas supply channel 8 is started, and at the same time, the auxiliary gas flows from the buffer dedicated channel 25 into the buffer channel 24. Thereby, the atmosphere in the buffer channel 24 is replaced with the auxiliary gas in a short time.

The auxiliary gas supply unit according to the present invention corresponds to the auxiliary gas supply channel 8 and the buffer dedicated channel 25.
According to the present embodiment, the auxiliary gas flows from the buffer dedicated flow channel 25 into the buffer flow channel 24 simultaneously with the supply of the auxiliary gas from the auxiliary gas supply flow channel 8, and the first auxiliary gas branch flow channel 9 and the second auxiliary gas branch flow. Since the bypass flow path 11 including the flow path 10 and the buffer flow path 24 is replaced with the auxiliary gas in a short time, the time from the start of the apparatus to the start of the measurement gas oxygen analysis can be greatly shortened.

  DESCRIPTION OF SYMBOLS 3 ... Sample flow path, 4 ... Measurement gas inlet, 5 ... Measurement gas outlet, 6 ... 1st auxiliary gas inflow port, 7 ... 2nd auxiliary gas inflow port, 8 ... Auxiliary gas supply flow path, 9 ... 1st Auxiliary gas branch channel, 10 ... second auxiliary gas branch channel, 11 ... bypass channel, 20 ... sample cell, 21 ... first flow sensor, 22 ... second flow sensor, 23 ... detection circuit, 23a ... first Detection circuit, 23b ... second detection circuit, 23c ... differential amplifier, 24 ... buffer channel, 25 ... buffer channel

Claims (8)

A sample flow path, a measurement gas inlet and a measurement gas outlet formed at both ends of the sample flow path, and a first auxiliary gas flow inlet and a first gas flow path provided opposite to the sample flow path on the measurement gas outlet side Two auxiliary gas inlets, and auxiliary gas passages connected to the first and second auxiliary gas inlets, supplying the auxiliary gas from an intermediate position of the auxiliary gas passages, and In the magnetic oxygen analysis method for calculating the oxygen concentration contained in the measurement gas by detecting a change in the flow rate of the auxiliary gas channel caused by applying a magnetic field to the sample channel near the gas inlet,
The auxiliary gas channel on the first auxiliary gas inlet side and the auxiliary gas channel on the second auxiliary gas inlet side communicate with each other by a bypass channel,
In the middle position of this bypass channel, a buffer channel that expands the channel is provided,
While detecting the first flow rate of the auxiliary gas flowing from the buffer channel to the bypass channel on the first auxiliary gas inlet side,
Detecting a second flow rate of the auxiliary gas passing through the buffer flow path and flowing into the bypass flow path on the second auxiliary gas inlet side;
A magnetic oxygen analysis method, wherein an oxygen concentration contained in the measurement gas is calculated based on the detected difference between the first flow rate and the second flow rate.   The magnetic oxygen analysis method according to claim 1, wherein a position where the first flow rate and the second flow rate are detected is the bypass flow channel that is equidistant from the buffer flow channel.   The magnetic oxygen analysis method according to claim 1 or 2, wherein a two-wire thermal flow meter is used to detect the first flow rate and the second flow rate.   4. The magnetic oxygen analysis method according to claim 1, wherein the auxiliary gas is supplied simultaneously to an intermediate position of the auxiliary gas channel and the buffer channel. 5. A sample flow path, a measurement gas inlet and a measurement gas outlet formed at both ends of the sample flow path, and a first auxiliary gas flow inlet and a first gas flow path provided opposite to the sample flow path on the measurement gas outlet side Two auxiliary gas inlets, and auxiliary gas passages connected to the first and second auxiliary gas inlets, supplying the auxiliary gas from an intermediate position of the auxiliary gas passages, and In a magnetic oxygen analyzer that calculates the oxygen concentration contained in the measurement gas by detecting a change in the flow rate of the auxiliary gas flow path caused by applying a magnetic field to the sample flow path near the gas inlet,
A bypass passage communicating the auxiliary gas passage on the first auxiliary gas inlet side and the auxiliary gas passage on the second auxiliary gas inlet side;
A buffer channel provided by enlarging the channel at an intermediate position of the bypass channel;
A first flow rate sensor disposed in the bypass flow path on the first auxiliary gas inlet side from the buffer flow path;
A second flow rate sensor disposed in a bypass flow path on the second auxiliary gas inlet side from the buffer flow path;
The first auxiliary gas flowing from the first auxiliary gas inlet detected by the first flow sensor and the second auxiliary gas inflow side passing through the buffer flow path detected by the second flow sensor. An oxygen concentration calculation unit that calculates an oxygen concentration contained in the measurement gas based on a difference from the second flow rate of the auxiliary gas flowing in the bypass flow path of the magnetic oxygen analyzer .   6. The magnetic oxygen analyzer according to claim 5, wherein the first flow sensor and the second flow sensor are arranged in the bypass flow path at a position equidistant from the buffer flow path.   The magnetic oxygen analyzer according to claim 5 or 6, wherein the first flow sensor and the second flow sensor are two-wire thermal flow meters.   8. The magnetic oxygen analyzer according to claim 5, further comprising an auxiliary gas supply unit that supplies the auxiliary gas to an intermediate position of the auxiliary gas channel and the buffer channel at the same time. .

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