JP2000155117A - Combustion oxidizing type element analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an inert gas such as nitrogen gas as a carrier gas for the combustion oxidizing type element analyzer. SOLUTION: An oxygen inlet unit 16, which is constituted by making the partition wall of a solid electrolyte cylindrical and providing platinum electrodes on its internal and external surfaces and takes oxygen in, making a current flow by connecting a DC power source between both the electrodes and migrating oxygen ions is arranged in a TC furnace 9, and an inert gas is passed through the oxygen inlet unit 16. Consequently, oxygen merges with the inert gas to obtain the carrier gas which improves combustion and is usable for the combustion oxidizing type element analyzer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion oxidation element analyzer for use in investigating and managing pollution such as organic pollution in water and soil and managing water quality of tap water and ultrapure water.

[0002]

2. Description of the Related Art A combustion oxidation type elemental analyzer burns a sample in an oxygen atmosphere using a carrier gas to generate an oxidized compound, and measures the oxidized compound by a suitable detection means to thereby determine the carbon content in the sample. , Which measures the amount of elements such as nitrogen.
Oxygen or an oxygen-containing mixed gas (for example, purified air) has been used. FIG. 5 shows a conventional schematic configuration example of a total organic carbon meter which is one of the combustion oxidation type elemental analyzers. As shown in the figure, the sample 5 is added with an acid such as hydrochloric acid 24 in an inorganic carbon removing unit 25 and is bubbled with high-purity air 21 used as a carrier gas, and the inorganic carbon (IC) in the sample is converted into CO _2. Volatilize. Then, the sample 5 is kept at 900 to 950 ° C. in the electric furnace 28,
High-purity air 2 in a catalytic combustion tube 26 filled with an oxidation catalyst
It is burned or decomposed under the oxygen of 1 to be converted to carbon dioxide. This carbon dioxide is dehumidified by the dehumidifier 27,
The measurement is performed by the infrared analyzer 29 and the measurement result is recorded in the recorder 30. Sample 5, hydrochloric acid 24 and high-purity air 2
A flow controller is required for a pump for sending 1 and a flow path of the high-purity air 21 to the inorganic carbon removing unit 25 and the catalytic combustion tube 26, but they are omitted in FIG.

[0003]

The conventional combustion oxidation element analyzer is constructed as described above. However, oxygen-containing mixed gas such as oxygen or high-purity air used as a carrier gas is installed in the analyzer. The problem is that it is not always available on the site. In particular, when the analyzer is used continuously online, the carrier gas must be supplied without interruption. On the other hand, for example, when performing water quality control of ultrapure water used in a semiconductor factory, an inert gas such as high-purity nitrogen gas can often be used abundantly, and if this can be used as a carrier gas for an analyzer, it will be large. Benefits can be obtained.

[0004] The present invention has been made in view of such circumstances, and has as its object to provide a combustion oxidation type elemental analyzer which can use an inert gas such as nitrogen gas as a carrier gas. I do.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, a sample is oxidized and decomposed by heat under a carrier gas, and a detection gas suitable for a generated gas of an oxidized compound is obtained. In a combustion oxidation type elemental analyzer for measuring the amount of elements contained in a sample by measuring by means, an oxygen introduction mechanism is provided in the analyzer, and the inert gas is passed through the oxygen introduction mechanism to improve the combustion support. Characterized in that the carrier gas can be used as a carrier gas. According to a second aspect of the present invention, there is provided the combustion oxidation type elemental analyzer according to the first aspect, further comprising an oxygen introduction mechanism using a solid electrolyte. FIG. 1 is a schematic explanatory view for explaining the structure and function of the oxygen permeable wall 18 constituting the oxygen introducing mechanism used in the present invention. The oxygen permeable wall 18 is formed of a solid electrolyte 18a such as stabilized zirconia, and porous platinum electrodes 18b and 18c having small holes 18d of a size such that oxygen molecules can pass therethrough are fixed on both sides thereof by coating or the like. ing. The DC power supply 17 is connected so that the outer platinum electrode 18b is (-) and the inner platinum electrode 18c is (+). In this state,
When current flows in the direction of the arrow, the (−) and (+) platinum electrodes 18
At b and 18c, a reaction according to the reaction formula shown in the figure occurs, and on the (−) electrode side, oxygen O ₂ and an electron combine to become oxygen ions and move in the oxygen permeable wall in the direction of the arrow,
At the (+) electrode side, oxygen ions emit electrons and oxygen O ₂ is collected. By mixing the oxygen thus collected with the inert gas, the inert gas can be converted into a carrier gas having a combustion supporting property.

[0006] The combustion oxidation type elemental analyzer of the present invention is configured as described above, and by using this, an inert gas can be used as a carrier gas.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The combustion oxidation type elemental analyzer of the present invention will be described below in detail with reference to examples. FIG. 2 shows an embodiment of the present combustion oxidation type elemental analyzer. In addition,
Components having functions similar to those of the conventional example shown in FIG. 5 are denoted by the same reference numerals. In this embodiment, a total organic carbon meter using a high-purity nitrogen gas as a carrier gas will be described, but the present invention can be similarly applied to other combustion oxidation element analyzers.

The total organic carbon meter according to the present invention comprises a high-purity nitrogen gas 1 having a constant flow of a sparge gas 3 and a carrier gas 4.
Flow rate control unit 2 that divides the sample into a liquid sample 5 and slide type TC sample injection unit 7 and slide type IC sample injection unit 1
4 port valve 6a and syringe 6b for supplying 0
A sample injecting unit 6 composed of a gas generator, an oxygen introducer 16 for introducing oxygen into the carrier gas 4 and a DC power supply 17, and a TC combustion tube 8 for burning the sample 5 under the carrier gas 4a to convert it into carbon dioxide. A TC furnace 9 for maintaining the TC combustion tube 8 and the oxygen introducer 16 at a constant high temperature, and an IC for converting inorganic carbon (IC) in the sample into carbon dioxide.
It comprises an IC reactor 12 containing a reaction solution 11, a dehumidifying gas processing unit 13 for dehumidifying carbon dioxide, an infrared gas analyzing unit 14 for measuring carbon dioxide, and a data processing unit 15.

FIG. 3 is a schematic perspective view showing an embodiment of the oxygen introducing device 16. As shown in the figure, a cylindrical body 16a having a circular cross section, porous platinum electrodes (hereinafter abbreviated as electrodes) 16b and 16c provided on the outer and inner surfaces thereof, and an electrode 16b
(-) And the DC power supply 17 connected with the electrode 16c on the (+) side. By changing the voltage value of the DC power supply 17, the amount of oxygen moving from the outer surface toward the inner surface can be adjusted, and the oxygen concentration at the inner surface can be changed.

The cylindrical body 16a of this embodiment is made of a material having an outer shape of 8 mm, an inner diameter of 6 mm, a length of 250 mm, and a material of stabilized zirconia. Main oxygen introducer 16
Is held at the high temperature of the TC furnace 8, for example,
When a DC current of 1 A flows, the amount of oxygen passing through the partition wall of the cylindrical body 16a becomes about 3.5 (ml / min). Assuming that the high-purity nitrogen gas flowing into the cylinder 16a is 150 (ml / min), the oxygen volume ratio in the synthesized carrier gas is about 2.
3%.

As the voltage value increases, the current also increases, and the oxygen partial pressure ratio (P ₀₂ / P ₀₁ ) where the external oxygen partial pressure is P ₀₁ and the internal oxygen partial pressure is P ₀₂ also increases. Above this value, there is a critical current determined by the cylindrical structure, the gas diffusion resistance at the porous layer / electrode interface and the conductivity of the solid electrolyte, and the oxygen introduction rate is also limited.

FIG. 4 is a front sectional view (a) and a side view (b) showing the structure of another embodiment of the oxygen introducing device. The oxygen introducer shown in the figure uses a plurality of oxygen introducers 20 each having a rectangular cross section, and both ends of the oxygen introducer 20 are each provided with a carrier gas inlet 22.
And a carrier gas outlet 23, and a DC power supply (not shown) is connected to each oxygen introducer 20. When the carrier gas flows from arrow A,
It is divided into the oxygen introducers 20 along the arrows, merges with the oxygen introduced from the outside as shown by the arrow, and is taken out from the arrow B.

This oxygen introducer has a larger surface area and a larger amount of oxygen to be introduced than the oxygen introducer 17 shown in FIG. By changing the shape and the current value, the amount of oxygen necessary for the type of sample can be easily obtained.

The analysis of a sample with the total organic carbon meter using the oxygen introducers 16 and 20 as described above is performed as follows. The sample 5 from which the dissolved carbon dioxide has been removed by the sparge gas 3 is sucked into the syringe 6b, and then is supplied to the slide TC sample injection unit 7 via the 4-port valve 6a together with the auxiliary carrier gas 4a that has passed through the oxygen introducer 16. Injected and burned in the TC combustion tube 8, the total carbon (TC) in the sample
Is decomposed and converted to carbon dioxide. This carbon dioxide is I
IC reaction liquid 11 and dehumidification gas processing unit 1 in C reactor 12
The measurement is performed by the infrared gas analyzer 14 via 3 and the measurement result is sent to the data processor 15. On the other hand, the sample 5 is injected into the IC reactor 12 via the sample injection section 6 and the slide type IC sample injection section 10 and reacted with the IC reaction solution 11 to convert inorganic carbon (IC) in the sample into carbon dioxide. After the conversion and passing through the dehumidifying gas processing unit 13, measurement is performed by the infrared gas analyzing unit 14 and the measurement result is sent to the data processing unit 15.
The total organic carbon (TOC) can be obtained by subtracting the inorganic carbon amount (IC) from the total carbon amount (TC).

As described above, by providing the oxygen analyzer in the combustion oxidation type elemental analyzer, it can be used even in an installation place where only an inert gas can be obtained. In addition, the current supply to the oxygen introducer is switched. In this case, the carrier gas can be selectively used depending on the presence or absence of oxygen in the carrier gas.

[0016] Incidentally, as the material of the oxygen introducer, in the present embodiment uses stabilized zirconia _{(Z r O 2 -Y 2 O} 3), is not limited to this, other solid electrolytes ( For example, ThO ₂ , Bi ₂ O ₃ ), stabilizers (eg, CaO, MgO) and the like can be used. Further, a mixed conductor (for example, La _0.5 Sr _0.5 MnO ₃ ) can be used, and in this case, oxygen can be introduced without applying a direct current from the outside.

[0017]

The combustion oxidation type elemental analyzer of the present invention is configured as described above, and uses an oxygen introducer made of a solid electrolyte to measure the amount of oxygen corresponding to the current value flowing between the inner and outer electrodes in the carrier gas. In this case, an inert gas such as a nitrogen gas can be used as a carrier gas, so that oxygen gas, purified air, and the like are not required.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the function of an oxygen permeable wall used in the present invention.

FIG. 2 is a configuration diagram showing an embodiment of a combustion oxidation type elemental analyzer of the present invention.

FIG. 3 is a schematic perspective view of the oxygen introducer of the present invention.

FIG. 4 is a front sectional view (a) and a side view (b) of another oxygen introducing device of the present invention.

FIG. 5 is a configuration diagram showing an embodiment of a conventional combustion oxidation element analyzer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... High-purity nitrogen gas 2 ... Gas flow control part 3 ... Sparge gas 4, 4a ... Carrier gas 5 ... Sample 6 ... Sample injection part 6a ... 4-port valve 6b ..Syringe 7 ... Slide type TC sample injection part 8 ... TC combustion tube 9 ... TC furnace 10 ... Slide type IC sample injection part 11 ... IC reaction liquid 12 ... IC reactor 13 ... dehumidification gas processing unit 14 ... infrared gas analysis unit 15 ... data processing unit 16 ... oxygen introducer

Claims (2)

[Claims] A combustion oxidizing element for measuring the amount of elements contained in a sample by oxidizing and decomposing the sample by heat under a carrier gas and measuring the resulting gas of an oxidized compound by a suitable detecting means. In the analyzer, an oxygen introducing mechanism is provided in the analyzer, and an inert gas is passed through the oxygen introducing mechanism so that the oxygen introducing mechanism can be used as a carrier gas having a combustion supporting property. Total. 2. The combustion oxidation element analyzer according to claim 1, further comprising an oxygen introduction mechanism using a solid electrolyte.