JPS5890151A - Direct emission spectrochemical analyzer for large size metal material - Google Patents

Abstract

PURPOSE:To perform a simple and rapid analysis of a metal material, by a method wherein an opening end of a cylinder tube having a plasma arc heater is brought into contact with a metal surface to evaporate it into a metallic fine particle, which, in turn, is conveyed by a gas carrier to an emission spectrochemical analyzer having a plasma exciting source. CONSTITUTION:A surface of a metal material 3 is fused by a plasma arc heater 4 of an enclosure type cylinder tube 2 for producing a fine particle whose opening end is brought into contact with a large size metal material 3, and a metallic fine particle is evaporated. A given quantity of the metallic fine particle is conveyed by a gas carrier through a conveyance gas distributor 12 to an emission spectrochemical analyzer 27 provided with a plasma exciting source to produce a plasma flame 18. This permits the simple and rapid analysis of a large size metal material without cutting of the material to a sample.

Description

[Detailed Description of the Invention] The present invention is most utilized in the metal manufacturing industry, and is an alternative to a solid-state emission spectrometer that targets sample pieces of a fixed shape. This invention relates to an optical emission spectrometer that directly analyzes large metal materials and the like.

In the metal manufacturing industry, analysis of the main components and trace components contained in metals and alloys is essential for quality control of metal and alloy manufacturing processes and products. For this analysis, a high voltage is generally applied between the metal sample piece and a counter electrode to cause a spray discharge or arc discharge, and the spectral line intensities of the excitation light based on the evaporated components are measured. Solid-state emission spectrometry, which determines the content of components, is most commonly used. However, this analytical method is subject to certain limitations on the shape of the sample due to the structure of the device that generates the discharge, etc., and it is usually necessary to prepare a sample piece with a flat surface of 15 mmφ or more. However, in the metal manufacturing process, if it takes a considerable amount of effort and time to cut out the sample pieces as described above, if you want to avoid collecting sample pieces for products as much as possible, or if you want to cut out sample pieces as much as possible, It is often difficult to collect samples when rapid analysis is required. For this reason, samples for analysis were not collected from the metal plate.

There has been a strong demand for the development of a new analytical device that can directly analyze square timbers, bars, etc. easily and quickly.

In view of this need, the present invention provides a new analysis method and device that can directly analyze large metal materials easily, quickly, and with high precision, based on the basic principles of plasma arc heating, evaporated particulate transport, and plasma excitation emission spectrometry. It is something to do.

The present invention will be explained in detail based on the embodiment of the present invention shown in FIG.

The apparatus of the present invention can be roughly divided into particulate generators: 1. Particulate transport pipe 6. It consists of a carrier gas distribution device 12 and an emission spectrometer 27 having a plasma excitation source. The particulate generator 1 is a part that irradiates the surface of a metal material with a plasma arc, heats and melts a part of the metal surface, and evaporates particulates representing the composition of the metal in the form of smoke. The cylindrical tube 2 for generating fine particles has an open bottom and a horizontal end surface, so that when it is set on the surface of the metal material 3, it becomes airtight.

The plasma arc heating device 4 is attached to the upper part of the cylindrical tube 2, and the plasma generating tube 5 is attached perpendicularly to the surface of the metal material 3, with a distance of usually about 5 to 10 cm between the two. The cylindrical tube 2 may be placed on the surface of the metal material to be analyzed from above, below, or lateral to the metal phase 3. The particle generator is small and portable. A portion of the surface of the metal material 3 is melted in a short time by the plasma flame generated from the plasma generation tube 5 of the plasma arc heating device 4, and the surface becomes overheated, evaporating fine particles representative of the composition of the metal material. Heating sources such as spark discharge, arc discharge, electron beam, or laser beam can be used instead of plasma arc, but plasma arc heating melts metals quickly, evaporates fine particles quickly, and Since the hot water temperature can be increased, components that are difficult to evaporate can also be easily evaporated, which is advantageous in improving analysis accuracy and shortening analysis time. The reason why the plasma flame generation port 5 is set at a position directly above the surface of the metal material 3 is to efficiently heat and evaporate the particles, and to provide a transport tube 6 for the evaporated particles.
The aim is to carry out transportation efficiently. If the plasma flame is irradiated with a certain angle of inclination to the surface of the metal 3, the evaporated particles will be spread along with the flow of the plasma flame when the plasma flame is reflected in the opposite direction from the metal surface. Transfer to the shunting transfer pipe 6 is hindered. The evaporated particulates are carried into a particulate transport pipe 6 which is installed as a concentric double pipe around the outer periphery of the plasma generation tube 5 with a narrow gap. The fine particles that evaporate in the form of smoke from the surface of the metal material 3 usually move upward from the metal surface due to convection caused by the high temperature of the plasma flame, and then some of them enter the plasma flame from above, and some of them evaporate from the surface of the metal material 3. spread to the surrounding area. In the present invention, which analyzes the amount of components in metal materials, unlike the case where fine particles are simply collected, the entire amount of evaporated fine particles or a constantly stable constant proportion is sent to the analyzer 27 (5) together with a carrier gas. Therefore, a more efficient particle transport technology is required. In the present invention, the fine particles that evaporate from the metal surface and rise directly above are prevented from dispersing to the surroundings, and are quickly carried on the flow of the carrier gas flowing above the multi-metal surface toward the entrance of the carrier pipe 6. I took a method to carry it away. That is, the fine particles rise from the metal surface that has been melted by the plasma arc, rise around the plasma flame, and return to the metal surface again, causing convection. On the other hand, the carrier gas introduced through the carrier gas inlet 9 attached to the top or side of the cylindrical tube 2 has only one outlet, the particulate carrier tube 6 provided around the plasma generation tube 5, so that the plasma flame is A gas flow is formed that enters the conveying pipe 6 from above the central metal material. Therefore, the fine particles that have evaporated and risen are drawn into the airflow of the carrier gas and are sent into the carrier pipe 6 at a constant dilution ratio. Therefore, as shown in FIG.
It is good to have a The outer diameter of the plasma generation tube 5 is usually 10
A small pipe of approximately wnφ is used, and therefore, the outer diameter of the conveying tube 6 is also small, 15 to 20 columns φ. Although it depends on the voltage and current of the plasma arc and the flow rate of gas such as Ar or He, by making the conveying tube 6 provided around the outer periphery of the plasma arc generating tube 5 a little shorter than the length of the plasma arc generating tube 5, Coarse particles caused by splashing are returned to the three metal surfaces, and only fine particles are transported.

7 is an electrode rod with a pressing force such as a spring, and metal 3
0 is in contact with the surface. Normally, a negative potential is applied to the plasma arc heating device 4, and a positive potential is applied to the metal material 3. The cylindrical tube 2 is electrically insulating.

It is best to make it from a material with good thermal conductivity, and boron nitride, which has good machinability, was the most suitable material, but it may also be made of a refractory material such as alumina or magnesia. In addition, in order to prevent the diffusion of particles into two cylindrical tubes, a tube with as small a diameter as possible is used to reduce the internal volume.

The evaporation rate and particle size of fine particles are influenced by the pressure of the evaporating atmosphere, the heating temperature, the type of atmospheric gas, and the like. The particle size of fine particles is particularly important as it affects the quantitative accuracy in emission spectroscopic analysis that uses a plasma excitation source.
It is necessary to make the particle size as small as possible and to adjust the particle size distribution. The fine particles generated for steel by the present invention are electrolyzed.

When investigated by microscopic observation, the particle size was found to be extremely fine, approximately 0.1 μm or less, and the width of the particle size distribution was narrow, making it ideal for plasma emission spectroscopic analysis.0 The evaporated fine particles were carried on a carrier gas. The gas is conveyed through the pipe 6 to the carrier gas distribution device 12, but when analyzing fine particles as in the present invention, the most important issue is to prevent the fine particles from adhering to and remaining on the inner walls of this part. .

Since the inner wall of the cylindrical particle generating tube 2 is heated by high heat generated by plasma arc heating, particles are difficult to adhere to and there is no problem of sloshing, but the temperature of the conveying tube 6 decreases, making it easier for particles to remain attached. The residual adhesion of fine particles may cause fluctuations in the number of fine particles in the carrier gas, or may cause contamination when the next metal material is analyzed, making it impossible to obtain accurate analytical values. Evaporated fine particles tend to aggregate or remain attached to the wall surface due to transport by slow and quiet gas flow or a drop in temperature. Therefore, it is necessary to make the diameter of the transport pipe 7 as small as possible to increase the flow rate of the transport gas.
As shown in the figure, a heating device j1 is provided to keep heating at all times.
Alternatively, it is effective to process the inner surface of the conveying tube 6, such as by making the tube 6 into a turbulent line shape to create a turbulent flow of the conveying gas. In addition, when the conveyor pipe is long, such as several tens of meters,
It is likely that some fine particles will remain, but in this case, consider the transport conditions so that the proportion of fine particles remaining is constant, and be sure to remove them at the end of the analysis of one sample. Contamination of the next sample could be prevented. As a result of various experiments, it was found that fine particles adhering to the inner wall of the tube can be easily peeled off and removed by blowing carrier gas at high speed within a short period of time on the adhesion edge. A method of removing the gas by increasing the gas blowing flow rate was adopted. This flow rate control of the carrier gas was carried out by automatic switching operation (9) of the flow rate regulator 1o of the carrier gas supply device M8 connected to the blowing pipe 9 attached to the cylindrical pipe 2. The flow 1 adjustment of the carrier gas is, for example, 10 to 1511 at the time of setting the cylindrical tube to the metal material to be analyzed.
The inside of the cylindrical tube is replaced with an inert atmosphere by flowing at a constant flow rate of 3 to 5,717 m1n when plasma arc heating is performed. 10-207/m immediately after measurement
in a cylindrical tube 2. Conveying pipe 6. A method is adopted to remove floating particles and adhered trace particles that may remain inside the carrier gas distribution device 12 etc. and remove them from the system.The particle transfer pipe 6 is connected to the carrier gas distribution device 12. .

The carrier gas distribution device 12 operates at a certain level in order to obtain an optimal flow rate of the carrier gas introduced into the plasma section 20, which once diffuses the fine particles sent together with the carrier gas from the carrier pipe 6 in the space and further agglomerates them. Particle sizing for discharging the part out of the system and distributing the carrier gas, or for sending only fine particles to the plasma section 20 by eliminating particles that have become particularly coarse due to agglomeration progressing while being transported out of the system. This is the part that performs the following functions. The distribution device 12 is heated on the outer periphery (10).The particle transport tube 6 is inserted from the side wall of a small diameter cylindrical tube to which the heating device 11 is attached, with the tube bed end facing upward, and the particle introduction tube 15 is inserted into the upper part of the cylindrical tube. The discharge pipe 13 equipped with a flow rate regulator 14 is installed at the bottom of the cylindrical pipe, and is installed vertically at a constant interval so as to face the end of the conveying pipe. These three pipes are all thin pipes with a diameter of about 10 mm, and coarse particles and distributed fine particles are removed from the bottom discharge pipe along with excess carrier gas.
3 and the remaining fine particles are introduced into the introduction pipe 15 together with a constant flow rate of the carrier gas. The flow rate regulator] 4 is interlocked with the operation of the flow rate regulator 10 of the carrier gas supply device 8 described above.

[Particle introduction tube] 5 is a plasma excitation emission spectrometer 27
connected to. The introduced fine particles are transferred to the introduction pipe 15 as shown in the figure. A high-temperature plasma portion 20 is carried into a triple-pipe plasma torch 18 consisting of a plasma gas supply pipe 16° and a cooling gas supply 17, and is generated by a high-frequency generator 19.
When it reaches this point, it is excited and emits light. In the example, the plasma gas contained 1 to 1.517 ml of Ar, the cooling gas contained 10 to 1.51 ml of Ar, and the particle transport gas contained 0 Ar.
It was carried out at a flow rate of 5 to 1 l/min. The emission spectrum of the excited particles is collected by a condensing lens 21, separated by a spectroscope 22 consisting of a slit, a reflecting mirror 232, and a diffraction grating 24, and a detector 25 consisting of a photomultiplier tube calculates the component content. The intensity of each spectral line is measured by the device 26, and the content of each component in the analysis sample can be quickly determined. Although a high-frequency inductively coupled emission spectrometer was most suitable for the analyzer 27 that excites fine particles to emit light, other types of arc discharge can be used.

A plasma excitation emission spectrometer such as a glow discharge or an atomic absorption spectrometer can be used.

According to the present invention, the time required for analysis from setting the particle generation cylindrical tube 2 to the surface of the metal material to be analyzed, generating particles, and determining the content of each component in the sample is about 5 minutes or less. It can be easily analyzed in time and with almost no human effort. In terms of quantitative accuracy, good results were obtained that were comparable to the method of cutting out a sample piece and analyzing it by emission spectrometry. As explained above, the present invention has made it possible to perform direct emission spectroscopic analysis, which can easily and quickly analyze multiple components at the same time, without having to collect sample pieces, for large metal materials, which has been difficult to analyze directly. became. The present invention is applicable to component segregation analysis for quality control of steel slabs, direct analysis for detecting the joint position of slabs in continuous casting of different steel types, direct analysis for determining the steel type of product steel plates, and semi-finished products in a red-hot state. It can be applied to direct analysis to check the composition of metals or online direct analysis of hot metal or molten steel.

The present invention provides a new analytical device that can easily and quickly analyze the amount of each component in metal materials by omitting operations such as cutting out sample pieces, and has made a significant contribution to this field. It is something.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an apparatus according to an embodiment of the present invention. 1... Particulate generator 2... Cylindrical tube for particulate generation 3... Metal material 4... Plasma arc heating device 6... Particulate transport tube 7... Counter electrode 8... Carrier gas supply Device 12...Carrier gas distribution device 15...Particle introduction pipe 18...Plasma torch (13) 22...Spectrometer 27...Emission spectrometer having a plasma excitation source (
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Claims (1)

[Scope of Claims] A blowing pipe connected to a gas supply device for transporting particulates whose flow rate can be freely adjusted at the top or side, and one end of which is provided in a concentric circle with a narrow gap around the outer periphery of the plasma emission tube, and the other end is used to transport the particles. A particulate transport pipe connected to a gas distribution device is attached, and a plasma discharge tube connected to a plasma arc heating device is attached perpendicular to the metal surface at the top, and the bottom is set in contact with the surface of the metal material to be analyzed. A particulate generator having an open opening with a horizontal end surface as shown in FIG. A carrier gas distribution device is equipped with a discharge pipe, and the distribution device is connected to the particle introduction pipe by a particle introduction pipe. Plasma light emitting device with plasma excitation source such as high-frequency inductively coupled plasma 1 Plasma light emission spectrometer consisting of a spectrometer, a detector, a component content calculation device, a counter electrode of a plasma arc heating device in contact with a metal material, etc. A direct emission spectroscopic analysis device for large metal materials characterized by being mainly configured.