JPH0450979B2 - - Google Patents

Description

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

[Prior Art] Recently, a new type of oxygen analyzer has been developed that can measure the amount of oxygen contained in metals, alloys, their compounds, or metalloids such as selenium and tellurium with high precision and in absolute value. Developed (Shinya Otsuka, Zensaku Kozuka, Transaction of the Japan
Institute of Metals.Vol−25, No.9639-648,
(Published September 1984).

This oxygen analyzer has an electrochemical oxygen pump using a solid electrolyte interposed in a closed gas flow path that circulates carrier gas, and by applying a constant DC voltage to the oxygen pump, By discharging oxygen, the oxygen partial pressure within the closed gas flow path can be maintained at a sufficiently low constant value. Before measurement, the oxygen in the carrier gas is exhausted, the inside of the closed gas flow path is maintained at a sufficiently low constant oxygen analysis pressure, and the sample is introduced into the closed gas flow path in this state. The introduced sample is heated and melted in a sample melting furnace, and oxygen is released from the sample. The oxygen released from the sample is carried by the carrier gas to the oxygen pump, and is discharged from the closed gas flow path by the oxygen pump, so that the inside of the closed gas flow path is again maintained at a constant low oxygen partial pressure. By measuring the amount of electricity required by the oxygen pump to discharge this oxygen, the amount of oxygen in the sample can be measured as an absolute value quickly and with high precision.

In the enzyme analyzer described above, the structure from the sample introducing means to the closed gas flow path to the sample melting furnace has conventionally been constructed as shown in FIG. In the figure, 31 indicates a closed gas flow path in which an oxygen pump 32 is interposed, and along the carrier gas circulation direction A, an introduction means 34 for a sample 33 is provided on the upstream side;
A sample melting furnace 35 is connected to the downstream side thereof.
This sample melting furnace 35 includes a U-shaped sample melting tube 36 made of a heat-resistant material such as silica, and a heating device 3.
It consists of 7. Further, a cooling means 38 is provided downstream of the sample melting tube 36 to condense metal vapor and return it to the sample melting furnace 35 side in order to suppress the vapor of the melted sample from flowing downstream. .

[Problems to be Solved by the Invention] However, in the oxygen analyzer configured as described above, since the sample dissolving tube 36 is composed of a U-shaped tube, the width of the sample dissolving tube 36 portion becomes large. However, it is difficult to downsize the sample melting furnace 35 as a whole. If the sample melting tube 36 and sample melting furnace 35 are large,
There is a problem that the heat capacity becomes large and the heating efficiency becomes poor.

In addition, since it has to be bent into a U-shaped tube, it may be difficult to manufacture depending on the material, and the inner structure of the sample melting section at the bottom of the U-shaped tube and the heating device 37 installed around it is complicated. There is also the issue of becoming.

Furthermore, since the cooling section in which the cooling means 38 is provided has a simple tube structure, there is a problem in that it is difficult to efficiently cool the gas or sample vapor flowing through the center of the tube. If the tube diameter is increased to increase the cooling surface area in order to increase the cooling efficiency in the cooling section, the volume of the sample dissolution tube 36 will become unnecessarily large, leading to inconveniences such as not being able to obtain the desired flow rate of the carrier gas. Providing fins or the like on the outer surface of the tube causes the problem that the entire sample melting furnace 35 and the cooling means 38 become larger.

The present invention focuses on these problems, and allows the structure of the sample dissolution tube and its surroundings to be simplified and downsized at the same time.
An object of the present invention is to provide an oxygen analyzer that can increase thermal efficiency in a cooling section.

[Means for Solving the Problems] The oxygen analyzer of the present invention that meets this objective includes a sample introduction means for introducing a sample into a closed gas flow path in which a carrier gas is circulated, and a sample introduction means for introducing a sample into the closed gas flow path; A sample melting furnace that melts the sample introduced from the introducing means and an electrochemical oxygen pump using a solid electrolyte that discharges oxygen in the closed gas flow path to the outside of the closed gas flow path are connected in series with each other. In the installed oxygen analyzer, a sample melting tube is installed upright in the sample melting furnace,
The sample dissolving tube includes an inner tube that guides the sample from the sample introducing means to a sample dissolving section provided at the bottom of the sample dissolving tube, and an inner tube that conducts gas from the sample dissolved in the sample dissolving tube section. It has a double pipe structure with an outer pipe leading to the oxygen pump side through the space between the outer pipe and the outer pipe.

[Function] In the oxygen analyzer configured as described above, the inside of the inner tube with a double tube structure serves as a passage for introducing the sample into the sample dissolving section, and the passage having an annular cross section between the inner tube and the outer tube serves as a passage for introducing the sample into the sample dissolving section. , used as a gas flow path from the dissolved sample.

In this double-tube, the inner tube and outer tube each have a simple tube structure, so the sample dissolution tube as a whole can have a simple structure, and the gas released from the sample introduced from the inner tube of,
Since the oxygen can be sent from between the inner tube and the outer tube to the oxygen pump side, it is possible to
The outer diameter of the double tube can be made much smaller than the width of the double tube. Therefore, the sample melting section provided at the bottom of the double tube has a simple structure and is miniaturized, and the heat capacity is also minimized, so that the thermal efficiency is increased compared to the conventional structure.

In addition, since the gas released from the sample flows through the annular passage between the inner tube and the outer tube, the entire flow passes near the inner peripheral surface of the outer tube, which is the cooling surface. Efficient cooling is achieved without particularly increasing the surface area.

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

1 to 3 show an oxygen analyzer according to an embodiment of the present invention. Figure 1 shows the overall configuration of the oxygen analyzer, and each directional valve is
This shows the state at the time of oxygen content analysis of the sample.

In FIG. 1, the path indicated by the thick line indicates a closed gas flow path 1 through which a carrier gas such as argas gas containing 0.01 to 10% hydrogen is circulated during oxygen content analysis of a sample. Each direction switching valve 2,
3 and 4 are four-way valves in this embodiment, which cause the carrier gas in the closed gas flow path 1 to flow in the direction of arrow A as shown in the figure when analyzing the oxygen content of a sample.

The closed gas flow path 1 includes a circulation pump 5 for circulating carrier gas along the carrier gas circulation direction A during measurement, and a sample 6 made of a metal, an alloy, a compound thereof, or a semimetal such as selenium or tellurium. A sample introduction means 7 is introduced into the closed gas flow path 1, a sample melting furnace 8 is used to melt the sample 6 from the sample introduction means 7 and release oxygen in the sample, and a sample melting furnace 8 is used to dissolve the sample 6 from the sample introduction means 7 and release oxygen from the sample 6, which is carried by the carrier gas. An electrochemical oxygen pump 9 using a solid electrolyte made of, for example, zirconia in which a stabilizer such as yttria, magnesia, or calcia is dissolved, is interposed in series to discharge the oxygen to the outside of the closed gas flow path 1. There is.

A flow meter 10 that can measure the flow rate (flow velocity) of the carrier gas circulated by the circulation pump 5 is provided upstream of the circulation pump 5 . Further, a carrier gas inlet 11 for introducing carrier gas into the closed gas flow path 1 is connected between the oxygen pump 9 and the circulation pump 5, and the carrier gas is introduced through the filter 12 and the directional control valve 2. It is becoming more and more like this.

Note that when replacing this closed gas flow path 1 with carrier gas, the directional control valves 2, 3, and 4 are switched as shown by arrow B, but the reduced pressure suction port 13 is connected to the end of the path. The gas in the closed gas flow path 1 that has been expelled by the carrier gas supply is discharged to the outside of the system via the filter 14 and the suction pump 15.

The sample introducing means 7 is configured in the shape of a container that can be sealed against the atmosphere, and is provided with a sample receiver 16 on which the sample 6 is placed and allows the sample 6 to fall downward by rotation or the like.

A sample melting furnace 8 is provided below the sample introduction means 7. The sample melting furnace 8 includes a sample introducing means 7.
While guiding the sample 6 from the sample to the sample dissolving section 17,
a sample dissolving tube 18 that guides the released gas from the sample 6 dissolved in the sample dissolving section 17 to the oxygen pump 9 side;
A heating device 19 for heating the sample melting section 17 is provided.

The sample dissolving tube 18 has a double tube structure including an inner tube 20 and an outer tube 21, and an internal passage 22 of the inner tube 20 serves as a sample introduction path to the sample dissolving section 17. A passage 23 between the oxygen pump 21 and the oxygen pump side passage 21 is configured as a discharge gas exhaust passage communicating with the oxygen pump side passage 24. The inner tube 20 and the outer tube 21 are made of heat-resistant tubes made of alumina, quartz, etc., and the connection part with the frame of the sample introduction means 7 at the upper end is connected with the O-ring 2.
5 and 26, respectively.

The lower end of the outer tube 21 has a sealed tube structure, and this portion constitutes the sample dissolving section 17. In this embodiment, the sample dissolving section 17 includes an outer tube 2.
A crucible 27 made of a heat-resistant material separate from crucible 1 is inserted, and the sample 6 is melted within the crucible 27.

The upper part of the sample melting tube 18 is provided with a structure that suppresses heat transfer from the heating device 19 side to the sample introducing means 7 side, and condenses sample vapor etc. from the sample melting section 17 to suppress its outflow to the downstream side. Cooling means 28 are provided. Although the cooling means 28 is constituted by a cooling fan in this embodiment, it may be any other means such as a water cooling jacket, a jacket using another refrigerant, or the like.

The operation of the embodiment device configured as described above will be explained.

First, the oxygen pump 9 is operated to exhaust oxygen in the carrier gas, and the inside of the closed gas flow path 1 is maintained at a sufficiently low constant oxygen partial pressure.

The sample 6 is dropped from the sample receiver 16 and placed in the inner tube 2.
0 through the sample introduction path 22, the sample dissolving section 17,
In other words, it is guided into the crucible 27. Crucible 27 is
The sample 6 is heated to a predetermined temperature by the heating device 19, and the sample 6 is melted. Oxygen is released from the dissolved sample 6, and the released oxygen is guided along the flow of the carrier gas to the released gas exhaust passage 23 between the inner tube 20 and the outer tube 21, and is closed via the passage 24. The gas is carried through the gas flow path 1 to the oxygen pump 9 and discharged to the outside of the closed gas flow path 1 by the oxygen pump 9. The amount of oxygen in the sample 6 is determined from the amount of electricity required by the oxygen pump 9 for this discharge.

The sample dissolving tube 18 has a double tube structure consisting of an inner tube 20 and an outer tube 21, and the bottom of the outer tube is configured as the sample dissolving section 17, so there is no need for a conventional U-shaped tube structure. The sample 6 can be guided to the sample dissolving section 17 along the carrier gas flow direction of the closed gas flow path 1, and the gas released from the sample 6 dissolved in the sample dissolving section 17 can be guided to the oxygen pump 9 side. In particular, the released gas exhaust path 23 is constructed around the sample introduction path 22, and the entire sample dissolution tube 18 is significantly reduced in size compared to the conventional U-shaped tube structure. In addition, inner pipe 2
0. Since the outer tube 21 has a simple circular tube structure, the structure is simplified, and in particular, the outer surface structure of the bottom portion of the outer tube, which is the sample dissolving section 17, is simplified. Due to the miniaturization, the heat capacity of the sample melting section 17 may be the minimum required for melting the sample 6, and the capacity of the heating device 19 is also miniaturized. Moreover, since the outer surface structure of the bottom of the outer tube 21 is simple, the heating efficiency from the heating device 19 is increased, and the structure of the heating device 19 itself is simplified.

Further, the released gas from the dissolved sample 6 is guided to the oxygen pump 9 side from the released gas exhaust path 23, which is an annular passage between the inner tube 20 and the outer tube 21, together with the carrier gas. Since it is an annular passage, there is no flow in the center of the tube as in the conventional case, and the entire amount of gas flows near the inner circumferential surface of the outer tube 21. Since the upper part of the outer tube 21 is cooled by the cooling means 28, the gas flowing inside is efficiently cooled in this part, and the steam etc. from the sample 6 is efficiently condensed and returned to the sample melting section 17 side. . Since efficient cooling is performed, there is no need to increase the cooling surface area by increasing the tube diameter, and the sample dissolution tube 18 can be downsized while simultaneously improving cooling efficiency.

[Effects of the Invention] As explained above, when using the oxygen analyzer of the present invention, the sample dissolution tube has a double tube structure, the sample is efficiently dissolved at the bottom of the outer tube, and the inner tube and outer tube are separated. By making it possible to efficiently cool the gas flow in the annular passage between the tubes, it is possible to simplify and downsize the structure of the sample dissolution tube and the heating device, cooling means, etc. installed around it. In the melting section, it is possible to improve heat transfer efficiency by simplifying the structure and improve energy efficiency by making it smaller, and in the cooling section, it is possible to improve cooling efficiency by using an annular passage structure while maintaining a small device. Effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an oxygen analyzer according to an embodiment of the present invention, FIG. 2 is an enlarged longitudinal cross-sectional view of the sample dissolution tube and surroundings of the device shown in FIG. FIG. 4 is a partially enlarged longitudinal cross-sectional view, and is a schematic overall configuration diagram of a conventionally known oxygen analyzer. 1... Closed gas flow path, 2, 3, 4... Directional switching valve, 5... Circulation pump, 6... Sample, 7... Sample introduction means, 8... Sample melting furnace, 9... Oxygen pump, 16... Sample receiver, 17... Sample dissolving section, 1
8... Sample dissolution tube, 19... Heating device, 20...
Inner tube, 21... Outer tube, 22... Sample introduction path, 23...
...released gas exhaust path, 27...crucible, 28...cooling means.

Claims (1)

[Claims] 1. Sample introduction means for introducing a sample into a closed gas flow path in which a carrier gas is circulated;
A sample melting furnace that melts the sample introduced from the sample introduction means and an electrochemical oxygen pump using a solid electrolyte that discharges oxygen in the closed gas flow path to the outside of the closed gas flow path are connected to each other. In the oxygen analyzer arranged in series, a sample melting tube is installed upright in the sample melting furnace, and the sample melting tube is transferred from the sample introduction means to a sample melting section provided at the bottom of the sample melting tube. An oxygen analyzer characterized in that it has a double-tube structure including an inner tube that guides the gas from the sample dissolved in the sample dissolving section and an outer tube that guides gas from the sample dissolved in the sample dissolving section to the oxygen pump side through the space between the inner tube and the oxygen pump. .