JPS6148100B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid sample aerosol generator for emission spectrometry. Generally, a vaporization method using arc discharge or spark discharge is used to generate an aerosol from a solid sample. The generated aerosol is then excited and analyzed by a light source such as a chemical flame, DC arc plasma, or inductively coupled plasma (ICP). In this analysis method, the evaporation process and excitation process of the sample are performed separately, so it is used as an effective method for elucidating the causes of various interferences that occur in ordinary emission spectroscopy, or as a means for detecting foreign materials in the metal industry. has been researched and developed. However, conventional devices exhibit several drawbacks when used as practical analytical devices. I'll give you that next.

(1) The sample evaporated by the discharge aggregates in the discharge chamber and the transport tube, and has a particle size distribution ranging from 0 to several hundred microns by the time it is transported to the light source. It is thought that the particles with larger diameters are not completely atomized within the light emitting source. If large-diameter particles with an order of magnitude greater number of atoms than completely atomized particles remain in the transport path or move unstable during the atomization process, the photometric intensity will decrease even if the ratio of the number of particles is small. This can cause instability. In conventional devices, all of these coarse particles were introduced into the luminescent source, resulting in unstable analysis results and poor analysis accuracy.

(2) Conventional devices used a single flow path in which particles were transported by gas flowing into the discharge chamber to vaporize the sample, and introduced directly into the luminescent source. The flow rate could not be determined independently. In addition, when increasing the flow rate for each analysis to release particles that have adhered to the discharge chamber or the transport tube, the increase in flow rate is limited by the conditions of the luminescent source, and the particles cannot be completely expelled, resulting in the influence of the previous sample. There was a strong possibility that he would remain.

The present invention solves the above-mentioned problems by providing an aerosol treatment section at the end of the aerosol transport tube, that is, immediately before the light emitting source, and providing a corresponding gas control system. Above (1)
As a countermeasure for this, since agglomeration of particles cannot be avoided, it was decided to take out only the fine particles after transportation, and a centrifugal separator (cyclone) was used. Regarding (2) above, a mixing section and a flow dividing section were created at the inlet and outlet sections of the cyclone section, respectively, so that arbitrary gas flow rates could be selected for the discharge section and the light emitting source section, respectively. The present invention will be explained below with reference to Examples.

FIG. 1 shows an embodiment of the invention. S is a discharge section, where the aerosol of the sample m generated by spark discharge is conveyed through a stainless steel tube P, and flows into the central tube Pm of the mixing section M, which has a coaxial double structure to prevent stagnation points. Then, it is mixed with the dilution gas flowing in from the outer pipe Pb of the mixing section, and becomes a gas flow having the required inflow velocity in the cyclone C. When this aerosol flows tangentially between the outer cylinder Cb and the inner cylinder Ci of the cyclone C, the sample particles descend downward while rotating. At that time, the particles drift toward the outer wall due to centrifugal force and Stokes resistance. This drift speed is proportional to the particle size, so the larger the particle, the shorter the time it takes for it to reach the wall. Particles that reach the wall fall into the dust hole, and only the fine particles that do not reach the wall move up the inner cylinder. The upper part of the inner cylinder is a flow dividing part, and the particles that have risen are introduced into the light emitting light source part L through a center tube Cm coaxially inserted into the inner cylinder to prevent the formation of stagnation points.
The aerosol taken out from the outer cylinder Cb is discharged through the control valve Ve. By adjusting this valve Ve, the amount of aerosol introduced into the light emitting source section L is adjusted. Inside the discharge section S and the transport pipe P for each analysis.
When cleaning the inside, the gas that was flowing into the mixing section M as a diluting gas is flowed into the discharge section S. This is several times the amount of gas during analysis, and the attached particles are flushed out to the extent that they do not pose a practical problem.
In this case as well, the amount of gas flowing into the light emitting source section L does not change and there is no adverse effect.

FIG. 2 shows a cross-sectional view of the cyclone section that was actually produced. 1 is a dust hole where captured coarse particles accumulate, 2 is a cyclone outer cylinder, and 3 is a cyclone inner cylinder. 4 is a mixing section, and 5 is a dividing section.

In this device, the aerosol particle size after treatment is
The calculated value was less than 10μ.

As described in detail above, by using a cyclone, we succeeded in creating an aerosol containing only fine particles from an aerosol with a wide particle size distribution that was conventionally introduced directly into the light emitting light source. In addition, by providing a mixing section and a dividing section, the gas flow rate in the discharge chamber and the light emitting source section can be determined independently, making it possible to select the optimum conditions for analysis, and making it possible to purge with a large flow rate of gas. Ta. Therefore, the drawbacks of conventional aerosol generators can be solved and practical analysis has become possible.

[Brief explanation of the drawing]

FIG. 1 is a piping diagram showing the entire apparatus of an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the cyclone particle separation section. S...Discharge section for sample vaporization, P...Transport tube, M...
...mixing section, C...cyclone, L...sample atomization light source.

Claims (1)

[Claims] 1 Consisting of a part that vaporizes the solid sample and a cyclone-type particle separator, the sample vapor generated in the part that vaporizes the solid sample is transferred to the cyclone-type particle separator using a carrier gas, A pipe for transporting the gas is inserted into and opened in the working gas supply pipe of the cyclone-type particle separator, and the gas pipe to bleed air from above the center of the cyclone-type particle separator is guided to the sample atomization section, and the bleed gas pipe is An exhaust pipe of the particle separator is provided on the outer periphery, and the flow rate of gas for conveying the sample vapor from the solid sample vaporizer to the particle separator, the amount of working gas supplied to the particle separator, and the amount of exhaust gas can be adjusted individually. A solid aerosol generator characterized by: