JPS6029724Y2 - Emission spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical emission spectrometer, and particularly to an optical emission spectrometer that is most suitable for a vacuum spectrometer using a vacuum pump.

A vacuum spectrometer is used to quantitatively analyze elements such as carbon, phosphorus, and sulfur in metal samples such as steel and pig iron.

FIG. 1 shows an example of such a spectroscopic analyzer.

The light emitting section causes the surface of the sample to emit light by, for example, spark discharge, and the sample excitation light from this emitted light is sent to the condenser lens 2.
As a result, the light is focused by the diffraction grating 31 in the spectrometer 3, and the light is diffracted by the diffraction grating 31.

At this time, when analyzing an element having a spectral line in the ultraviolet region, the spectral line will be absorbed by the air and measurement will be impossible. Make a vacuum.

Note that the spectrum is measured by a detector 33 composed of a photomultiplier tube or the like, and is further output to a display device via a data processing circuit (not shown).

Further, an entrance slit 34 is provided on the entrance side of the diffraction grating 31, and an exit slit 35 is provided on the straight line between the diffraction grating 31 and the detector 33 and near the detector 33.

Incidentally, in the apparatus shown in FIG. 1, a vacuum pump is essential in its construction, but oil is used in the lubrication system of the pump, which causes heat generation in the pump body and internal pressure of the spectrometer 3. Due to an imbalance with the internal pressure of the pump 32, the oil evaporates and diffuses into the spectrometer 3.

Although the spectroscope 3 is always kept at a temperature of 30±1° C., the periphery of the condenser lens 2 is connected to the light emitting unit 10 and is therefore in contact with the outside air.

Therefore, the oil vapor diffused inside the spectrometer 3 is absorbed by the outside air (22±1
Dew condensation occurs on the two surfaces of the condenser lens due to the difference in temperature (°C).

In addition, burn-in occurs due to discharge light during analysis, and light in the measurement spectrum line (1,600A to 4.200A) is absorbed, resulting in a decrease in emission intensity.

In particular, absorption of light at short wavelengths (2,000 A or less) appears prominently, which is a significant factor in reducing analysis accuracy.

An object of the present invention is to provide a spectroscopic analyzer that prevents condensation and burn-in of lubricating oil vapor from a pump on a condensing lens.

This invention focuses on the fact that condensation and burning of oil vapor on the condensing lens is caused by temperature differences in the atmosphere, and that oil vapor intrudes into the condensing glass, and heats the condensing lens. At the same time, an adsorption member for adsorbing oil vapor is provided at the entrance of the condensing lens section.

FIG. 2 is a block diagram showing an embodiment of the present invention.

Heaters 11a and llb such as nichrome wire are installed in the condensing lens part.
is installed and controlled by the heating control circuit 12.

The heating control circuit 12 is controlled to a constant temperature (for example, 35° C.) by a temperature detector (thermistor) 13 attached to the condenser lens.

On the other hand, a cylindrical absorber 36 is attached to the wall surface of the spectrometer 3 on the inside of the connection surface with the condensing lens 2 of the spectrometer 3.
The output light beam of the condensing lens 2 is made to pass through the interior of the adsorber 36.

As shown in FIGS. 3 and 4, the adsorber 36 is a two-layer cylindrical body with a fine wire mesh 361 (approximately 60 mesh) lined inside and an outer casing 362 provided at a predetermined interval. ,
A protrusion 364 (having a wire mesh 365 on the upper part)
An adsorbent 363 (for example, Molecular Sieve (trade name: 2TrrI)) is provided to adsorb oil vapor inside these layers.
nφ×5Trr! Fill with IL pellets).

With the above configuration, the oil vapor absorber 36 of the pump lubricating oil
Although only a small amount of oil vapor enters the interior, this small amount of oil vapor that enters is also absorbed by the adsorbent 363.

Furthermore, even if the oil vapor that was not absorbed by the absorber 36 reaches the condensing lens 2, the condensing lens 2 is heated and there is no temperature difference with the temperature inside the spectrometer 3, so the oil vapor condenses. There is no need to worry.

Note that the protrusion 363 provided on the adsorber 36 has the width of the slit 34 (20 μ x 10 m) when the vacuum pump 32 is in operation.
This is to avoid the time it takes to create a vacuum inside the suction device 36 because m) is small, and the wire mesh 3 of this protrusion 364
It is rapidly evacuated through the 65 plane.

The degree of contamination of the condenser lens is evaluated by the α value calculated by the following formula.

1\C sappo (xx, -xJ However, XIo: The upper standard value is a preset standard value on the high content range side.

The standard value for the lower part of Xjo2 is a preset standard value for the low content area.

Xl: Upper measurement value is an analysis value measured after an arbitrary period of time of the sample for which the upper standard value was determined.

X, The second lower measurement value is an analysis value measured after an arbitrary period of time of the sample from which the upper standard value was determined.

In other words, for example, in the case of C analysis of steel, C of a certain steel type
If the content ranges from 0.1 to 1%, the upper standard is the spectral intensity XIO when a sample with 1% C content is analyzed with an uncontaminated analyzer, and the lower standard value is This is the spectral intensity XJo when analyzing a sample with a C content of 0.1%, and these upper and lower standard values change from XIO to X and from Xjo to Xj, respectively, as the analyzer becomes contaminated over time. Spectral intensity decreases.

This is illustrated in FIG. 5, where the degree of contamination α can be expressed as the slope ratio of a straight line connecting the upper and lower standard values to a straight line connecting the upper and lower measured values.

When this α value is compared with the results of implementation according to the present invention, conventionally it took only about 10 hours to reach α = 1.0 to 1.3, but according to the present invention, it took about 500 hours. It has been confirmed that it can be extended.

As described in detail above, according to the present invention, dew condensation and burn-in on the condenser lens can be prevented, and the following effects can be specifically obtained.

(1) The durability time of the condenser lens increases.

(2) Analysis can be performed for a long time under the same conditions.

(3) Since there is no decrease in emission intensity, analysis accuracy can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional spectroscopic analyzer, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a side partial cross-sectional view of an adsorber according to the present invention, and Fig. 4 is a block diagram showing the adsorption device according to the present invention. FIG. 5 is a cross-sectional view taken along the IV-IV plane of the vessel, and FIG. 5 is a diagram showing the relationship between spectral intensity and element content. 2...Condensing lens, 3...Spectroscope, 1
0... Light emitting part, lla, llb... Heater,
12... Heating control circuit, 13... Temperature detector, 31... Spectrometer, 32... Vacuum pump, 34, 35...・Slit, 36...
...Adsorption device.

Claims (1)

[Scope of utility model registration request] The spectral lines of the sample from the light emitter are guided through a condensing lens to a diffraction grating in a vacuum spectrometer, where the diffraction grating separates them into measurement spectral lines, and when the spectra are measured, the elements of the sample are detected. In the optical emission spectrometer for analyzing the spectrometer, a heater is provided to maintain the condensing lens part at least at a temperature within the spectrometer, and a heater is provided inside the spectrometer at a connection surface with the condensing lens, and the inside of the condenser is An optical emission spectrometer characterized by comprising an adsorber that is provided so that the optical output of the optical lens can pass therethrough, and that adsorbs oil vapor present inside the optical lens.