JPH0426706B2 - - 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.

[Conventional technology]

Recently, a new type of oxygen analyzer has been developed that can measure the amount of oxygen contained in metals, alloys, their compounds, and metalloids such as selenium and tellurium with high precision and absolute values (Otsuka Written by Shinya and Zensaku Kozuka, Transaction of the Japan
Institute of Metals, Vol-25, No.9639-648
Page, 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 partial 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.

[Problem that the invention seeks to solve]

In the oxygen analyzer configured as described above, in order to accurately measure the amount of oxygen in the sample, the sample must be solid in the sample introduction means and introduced into the sample melting furnace from the sample introduction port. It is desired that the sample be dissolved for the first time, and that the oxygen in the sample be released into the closed gas flow path through dissolution. Furthermore, it is desirable that the melting temperature be set to a temperature that corresponds to the purpose of measuring the sample, for example, the purpose of using the metal sample.

However, when measuring a low melting point sample (such as Ga [melting point 29°C]) using an oxygen analyzer like the one mentioned above, the temperature of the sample introduction means increases considerably due to heat transfer from the sample melting furnace. Because
The sample may already be vaporized or liquid at the sample inlet. Furthermore, even if heat transfer from the sample melting furnace side is suppressed, there is a risk that a sample such as Ga, which has a melting point close to room temperature, may become liquid before being introduced into the sample melting furnace.

If the sample vaporizes or becomes liquid in this way, it becomes difficult to introduce the sample into the sample melting furnace, and it also becomes difficult to determine the starting point of the oxygen discharge from the sample by the oxygen pump, making it difficult to measure the sample. There is a problem that an error may occur.
In addition, as mentioned above, depending on the purpose of measurement, it may be necessary to set the melting temperature of the sample to a predetermined temperature and measure the amount of released oxygen at that temperature. If the dissolution proceeds, there is a risk that oxygen release at the target dissolution temperature may not be achieved accurately.

In view of the above-mentioned problems, the present invention makes it possible to reliably maintain a solid state even with a low melting point sample before introducing it into a sample melting furnace, and to maintain the sample at a predetermined temperature in the sample melting furnace. The purpose is to achieve the targeted release of oxygen from the sample in the sample melting furnace.

[Means for solving problems]

The oxygen analyzer of the present invention that meets this objective includes a sample introduction means for introducing a sample into the closed gas flow path in which a carrier gas is circulated, and a sample introduction means for dissolving the sample introduced from the sample introduction means. In an oxygen analyzer in which a sample melting furnace 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 arranged in series, the sample is introduced. The sample inlet of the means is provided with a cooling device capable of cooling the sample introduced into the closed gas flow path.

[Effect]

In the oxygen analyzer configured in this way, the sample inlet of the sample introducing means is cooled to an appropriate temperature by the cooling device, so that the sample held in the sample inlet before being put into the sample melting furnace is It is kept at a low temperature, preventing it from vaporizing or turning into a liquid, thus keeping it in a solid state. At the beginning of the measurement, the sample kept in a solid state is introduced into the sample melting furnace.
There, the sample is dissolved at a predetermined temperature, and the oxygen in the sample is released into the closed gas flow path. Therefore, the sample is reliably melted only in the sample melting furnace, oxygen in the sample is released accurately from the start of measurement, and the amount of oxygen in the sample at a predetermined melting temperature is accurately measured.

〔Example〕

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

The figure shows the overall configuration of an oxygen analyzer according to an embodiment of the present invention.

In the figure, 1 indicates a closed gas flow path 1 through which a carrier gas consisting of argon gas containing, for example, 0.01 to 10% hydrogen is circulated. Closed gas flow path 1
includes a sample introducing means 3 for introducing the sample 2 into the closed gas flow path 1, and a sample 2 introduced from the sample introducing means 3.
A sample melting furnace 4 is used to melt the gas, and a solid electrolyte made of zirconia with a stabilizer such as ittria, calcia, or magnesia dissolved therein is used to discharge oxygen in the closed gas flow path 1 to the outside of the closed gas flow path 1. The electrochemical oxygen pumps 5 used are arranged in series with each other.

In this embodiment, the sample introduction means 3 includes a sample introduction port 6 connected to the closed gas flow path 1 in a T-shape, a rubber stopper 7 that blocks the sample introduction port 6 from the atmosphere, and a rubber stopper 7.
The sample 2 in the sample introduction port 6 is passed through the sample melting furnace 4.
It consists of an injection rod 8 that is dropped to the side.

In this embodiment, the sample melting furnace 4 disposed downstream of the sample introduction means 3 includes a U-shaped sample melting tube 9 for melting the sample 2 that has been dropped therein, and a sample melting tube 9 for dissolving the sample 2 therein. and a heating device 10 for heating the melting tube 9.

A suitable cooling means 1 is provided downstream of the sample melting furnace 4.
1 is provided to condense the sample vapor etc. from the sample melting furnace 4 and prevent it from flowing into the downstream side.

Note that 12 is a filter that removes foreign substances and increases the degree of diffusion of the released oxygen from the sample 2 sent to the oxygen pump 5 in the carrier gas. Further, 13 is a circulation pump that circulates the carrier gas within the closed gas flow path 1. Reference numeral 14 is a supply port for supplying carrier gas to the closed gas flow path 1, and also serves as a vacuum suction port when the gas in the closed gas flow path 1 is initially discharged and replaced with carrier gas. 15 is a valve.

The sample introduction port 6 of the sample introduction means 3 described above is provided with a cooling device 16 capable of cooling the sample 2 within the sample introduction port 6 to a predetermined temperature. Cooling device 16
In this embodiment, it is configured to circulate a refrigerant (for example, cooling water), and a jacket 17 for refrigerant circulation is provided around the sample introduction port 6. The refrigerant circulation is performed by a pump 18, and a cooler 19 cools the refrigerant to a predetermined temperature in the circulation circuit.
is mediated. Control to a predetermined temperature is performed via thermosensor 20.

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

The sample introduction port 6 is cooled to a predetermined temperature through the jacket 17 by the circulation of the coolant by the cooling device 16. A sample 2 for oxygen content measurement is held in the sample inlet 6, and the sample 2 is also cooled to a predetermined temperature through cooling of the sample inlet 6.
For example, if the sample 2 is a low melting point sample such as Ga as described above, the temperature of the sample 2 is controlled to be lower than its melting point.

Therefore, even if some heat is transferred from the sample melting furnace 4 side, partial melting of the sample 2 in the sample inlet 6 is completely prevented, and the sample 2 is kept in a solid state. Further, even if the sample 2 has a low melting point close to room temperature, it is kept in a solid state by being cooled to a temperature below that temperature.

In this state, and in a state where the carrier gas in the closed gas flow path 1 is brought to a sufficiently low constant oxygen partial pressure by the oxygen pump 5 discharging oxygen, the measurement is started. A solid sample 2 is dropped by an injection rod 8 and sent to a sample dissolution tube 9. The introduced sample 2 is melted by heating to a predetermined temperature by the heating device 10, and oxygen in the sample 2 is released into the closed gas flow path 1. The released oxygen is carried by the carrier gas to the oxygen pump 5 and discharged outside the closed gas flow path 1 via the solid electrolyte. quantity is required.

Since the sample 2 is kept in a completely solid state in the sample introduction port 6, it is easily dropped by the injection rod 8 at the start of the measurement. In addition, since the sample 2 is not dissolved and releases oxygen while being held in the sample inlet 6, it is ensured that the sample 2 is dissolved only in the sample dissolution tube 9, and that oxygen is reliably dissolved during the predetermined measurement time. emit. Therefore, the measurement start point is clear, and the amount of electricity required for exhausting the released oxygen in the oxygen pump 5 can also be easily measured.

〔Effect of the invention〕

As explained above, when using the oxygen analyzer of the present invention, a cooling device is provided at the sample introduction port, so that even a low melting point sample can be kept in a completely solid state before being introduced into the sample melting furnace. So,
In addition to making it easier to introduce the sample into the sample melting furnace, it also prevents oxygen from being released from the sample before the measurement begins, and allows oxygen to be released accurately at the specified measurement time to improve measurement accuracy. You can get the effect that you can.

In addition, the release of oxygen from the sample into the closed gas flow path is
Since the measurement can be carried out only in the sample melting furnace at a predetermined temperature, it is also possible to accurately measure the amount of oxygen in the sample depending on the measurement purpose.

[Brief explanation of drawings]

The figure is an overall configuration diagram of an oxygen analyzer according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Closed gas flow path, 2... Sample, 3... Sample introduction means, 4... Sample melting furnace, 5... Oxygen pump,
6...Sample introduction port, 8...Injection rod, 9...Sample dissolution tube, 10...Heating device, 13...Circulation pump,
16... Cooling device, 17... Jacket, 18...
...Pump, 19...Cooler, 20...Thermosensor.

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. An oxygen analyzer arranged in series, characterized in that a cooling device capable of cooling a sample introduced into the closed gas flow path is provided at the sample introduction port of the sample introduction means.