A melt immersion probe, an on-line detection device and a detection method based on LIBS technology

Abstract

The present invention relates to a melt immersion probe, an on-line detection device and a detection method based on LIBS technology, which comprises a probe body. The probe body is in an inverted conical shape, with openings at its top end and bottom end respectively. An air inlet pipe and an air outlet pipe are respectively arranged on the side wall of the probe body, and air valves are respectively arranged on the air inlet pipe and the air outlet pipe. The periphery of the bottom opening of the probe body contracts towards the axis of the probe body to form a hemispherical shape, and a small hole is formed at the axis. With the above technical solution, the probe can extend into any depth and position of the molten liquid metal at any angle, reducing the steps of laser ranging and focusing adjustment, saving costs and time, truly realizing real-time on-line detection, and providing accurate detection, so as to accurately control the content of each element in the molten liquid metal, make real-time adjustments, ensure product performance and quality; eliminate potential safety hazards, reduce the labor intensity of workers, realize the automation and intelligence of the smelting process, and reduce energy waste and emissions.

Description

Technical Field

[0001] The present invention relates to the field of long-distance on-line monitoring of high-temperature liquid components, and particularly relates to a melt immersion probe, an on-line detection device and a detection method based on LIBS technology. Background Art

[0002] During the smelting process of steel and alloys, it is necessary to diagnose the chemical composition and temperature of molten liquid metal in real time to determine the end point of smelting, thereby controlling the properties of the finished metal material. The traditional smelting process adopts an off-line detection method of manual sampling and sample preparation. After a series of processes such as sampling, cooling, grinding, and polishing, this off-line detection method needs to be measured and analyzed on an analytical instrument. The whole process takes 4 minutes, accounting for 10% of the smelting time. It is difficult for the properties of the metallurgical finished materials produced to meet the expected standards, and at the same time, it causes energy waste.

[0003] In recent years, more and more equipment manufacturing has put forward strict requirements for the material properties and quality of key components (such as high-speed bearings and high-speed train wheels), resulting in an increasingly urgent demand for sensors and methods for on-line continuous and stable detection of the chemical composition and temperature of molten metal with ultra-high temperature resistance and high reliability in smelting production. On-line detection devices based on laser-induced breakdown spectroscopy (LIBS) have emerged. LIBS is a technology that uses a laser to excite a plasma and then uses the emission spectrum of the plasma for detection. The LIBS technology does not require sample pretreatment and is applicable to solids, liquids, and gases. Therefore, it shows significant application value in in-situ, on-line, real-time, and non-contact analysis.

[0004] Currently, there are two types of on-line molten metal detection devices based on LIBS technology. The first type mainly focuses on close-range and open optical path detection. There is an optical structure in the high-temperature resistant probe part, and the structure is complex. In the harsh environment of high temperature and soot, the air in the open space has strong absorption of ultraviolet and deep ultraviolet spectra. Some non-metallic elements, such as C, S, P and other elements, are the most important elements for quality control and determination of the smelting end point. Their plasma characteristic spectra are mainly distributed in the ultraviolet and deep ultraviolet regions. Therefore, effective detection of ultraviolet and deep ultraviolet spectra cannot be carried out. In addition, the probe cannot penetrate deep into the liquid metal, and the detection process will also be interfered by slag. The second type mainly focuses on in-situ and on-line detection probes for the composition of molten metal in metallurgy at a long distance. The high-temperature resistant probe at the front end is placed into the molten metal in metallurgy, forming a sealed space inside, filled with inert gas to achieve an optical path environment of inert gas. There are no optical elements inside; the high-temperature resistant probe includes an external refractory part and an inflation part, and its bottom is an open structure, but the problems are as follows: due to the open structure at the bottom, first, after the probe is placed, the liquid metal at the bottom will pour into the probe, and liquid metal laser ranging needs to be carried out, and then focusing adjustment is required, which takes a lot of time. The lag of the optical system focusing causes real-time disturbance to the plasma spectrum of the current molten metal obtained by the spectrometer, resulting in deviation of composition and temperature measurement, and real-time detection cannot be truly achieved; second, during the smelting process, the molten metal is in a boiling state, the metal liquid level will fluctuate, the plasma page is unstable, resulting in uncontrollable fluctuation of ion spectral lines, and bringing detection composition deviation; third, when the probe extends into the molten metal, the slag will also pour into the probe along with the molten metal, interfering with the detected composition and unable to accurately detect the true composition of the molten metal; in addition, due to the material of the probe itself, the probe cannot be immersed in the molten metal at more than 1700 degrees for too long a time. Otherwise, under the action of heat conduction, the complex optical path of excitation and collection is in a high temperature, and thermal radiation generates noise for the spectral collection at the rear end, so the detection time is also shortened accordingly. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a melt immersion probe based on LIBS technology that can be placed into the molten liquid metal to be measured in a metallurgical furnace at any angle and depth without adjusting laser ranging and focusing adjustment.

[0006] A melt immersion probe based on LIBS technology of the present invention adopts the following technical solutions: it includes a probe body, the probe body is in an inverted conical shape, with openings at its top and bottom respectively, and an air inlet pipe and an air outlet pipe are respectively arranged on the side wall of the probe body, and air valves are respectively arranged on the air inlet pipe and the air outlet pipe; the periphery of the opening at the bottom of the probe body shrinks towards the axis of the probe body to form a hemispherical shape, and a small hole is formed at the axis.

[0007] Further, the diameter range of the small holes is 1 mm - 5 mm.

[0008] Further, the diameter of the small holes is 2 mm.

[0009] Further, the probe body, the intake pipe, and the exhaust pipe are all of double-layer structure, which includes an inner layer and an outer layer. The inner layer is formed of ceramic material, and the outer layer is formed of high-temperature resistant and heat-insulating carbon-carbon based ceramic material.

[0010] An on-line detection device for melt based on LIBS technology, which adopts the above-mentioned melt immersion probe based on LIBS technology, further includes a rear-end console and a sensing unit. The rear-end console is electrically connected to the sensing unit; the sensing unit includes a box body and an optical system arranged in the box body. The bottom of the box body is connected to the top end of the probe body. An opening corresponding to the opening at the top end of the probe body is provided at the bottom of the box body, and an optical window is provided at the connection between the opening at the bottom of the box body and the opening at the top end of the probe body.

[0011] Further, the box body is of double-layer structure, which includes an inner layer and an outer layer. The inner layer is formed of ceramic material, and the outer layer is formed of high-temperature resistant and heat-insulating carbon-based ceramic material.

[0012] Further, the optical system includes a laser generator, a beam expanding and focusing module, a remote signal collection module, a fiber optic coupling module, and a fiber optic spectrometer. The fiber optic spectrometer is electrically connected to the rear-end control platform. The laser generator emits a laser beam, which is focused by the beam expanding and focusing module and reaches the small holes at the bottom end of the probe body, ablating the molten liquid metal to be measured to generate plasma. The plasma cools and expands under the induction of the laser to emit signal light. The signal light of the plasma is transmitted to the remote signal collection module, and then coupled by the fiber optic coupling module and then introduced into the fiber optic spectrometer.

[0013] Further, the optical system further includes a first reflector and a second reflector. The axis direction of the laser beam emitted by the laser generating module is coaxially arranged with the remote beam expanding and focusing module; the first reflector is arranged on the optical axis in the emission direction of the remote beam expanding and focusing module, forming a 45-degree angle with its optical axis. The second reflector is arranged on the optical axis in the incident direction of the remote signal collection module, forming a 45-degree angle with its optical axis. The central connection line between the first reflector and the second reflector is perpendicular to the axes of the remote beam expanding and focusing module and the remote signal collection module; a fiber optic coupling module is arranged on the optical axis in the emission direction of the remote signal collection module. The fiber optic coupling module is connected to the fiber optic spectrometer through a fiber optic cable, and the fiber optic spectrometer is electrically connected to the rear-end control platform.

[0014] Furthermore, the optical system further includes a real-time imaging module and a beam splitter. The beam splitter is disposed between the remote signal collection module and the fiber optic coupling module and is on the optical axis in the outgoing direction of the remote signal collection module. The real-time imaging module is vertically disposed on the optical axis in the reflection direction of the beam splitter and is electrically connected to the backend control platform.

[0015] A detection method of a melt on-line detection device based on LIBS technology is applied to the above-mentioned melt on-line detection device based on LIBS technology, and it includes the following steps:

[0016] The melt immersion probe extends into the metallurgical furnace at any angle, and its bottom end passes through the slag layer on the surface of the molten liquid metal in the metallurgical furnace and immerses into the molten liquid metal to be measured. Inert gas is filled into the intake pipe, and the air in the probe body flows out from the exhaust pipe, so as to form a sealed inert gas environment in the probe body;

[0017] The backend control platform controls the laser generation module to emit a laser beam, which is focused through the remote beam expander and focusing module and reaches the small hole at the bottom end of the probe body through the optical window, ablating the molten liquid metal to be measured to generate plasma. The plasma cools and expands under the induction of the laser to emit signal light. The signal light of the plasma is transmitted to the remote signal collection module through the inert gas environment in the probe body, and then transmitted to the fiber optic coupling module for coupling and then imported into the fiber optic spectrometer for optical signal acquisition and photoelectric conversion, and fed back to the backend control platform to complete the acquisition of the plasma signal light.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. The outer periphery of the opening at the bottom end of the probe body shrinks towards the axis of the probe body into a hemispherical shape, and a small hole is formed at the axis. Utilizing the internal surface tension of the molten liquid metal, the molten liquid metal and the slag will not backflow into the probe body, and the fluctuations of the boiling molten liquid metal will not affect it either. The molten liquid metal always adheres to the small hole at the bottom of the probe. Therefore, the probe can extend into any depth and position of the molten liquid metal at any angle, as long as the laser beam remains focused on the small hole at the bottom end of the body, providing a stable quasi-plasma point light source with a certain object distance. Therefore, it also reduces the laser ranging and focusing debugging steps, saves cost and time, truly realizes real-time on-line detection, and provides accurate detection, so as to accurately control the content of each element in the molten liquid metal, make real-time adjustments, ensure product performance and quality; eliminate potential safety hazards, reduce the labor intensity of workers, make the smelting process automated and intelligent, and reduce energy waste and emissions;

[0020] 2. A probe and a box body with a double-layer structure are adopted. The inner layer of the probe and the box body is formed of a ceramic material, and the outer layer is wrapped with a heat-resistant carbon-carbon-based ceramic material capable of withstanding a temperature of 2300 °C. The outer layer has the functions of heat insulation and heat resistance, preventing the influence of heat conduction on the double optical path and optical elements, so as to generate noise in spectrum collection; prolonging the continuous detection time without the need for an additional temperature adjustment module. Description of the Drawings

[0021] The drawings described herein are used to provide a further understanding of the present application. In the drawings:

[0022] Figure 1 It is a schematic structural diagram of an embodiment of the present invention. Detailed Embodiments

[0023] See Figure 1 As shown, a melt immersion probe based on LIBS technology in an embodiment includes a probe body 3. The probe body 3 is in an inverted conical shape, with openings at its top and bottom respectively. An air inlet pipe 31 and an air outlet pipe 32 are respectively provided on the side wall of the probe body 3, and air valves 33 are respectively provided on the air inlet pipe 31 and the air outlet pipe 32; the outer periphery of the bottom opening of the probe body 3 contracts towards the axis direction of the probe body 3 to form a hemispherical shape, and a small hole 34 is formed at the axis.

[0024] Further, the diameter range of the small hole 34 is 1 mm - 5 mm.

[0025] Further, the diameter of the small hole 34 is 2 mm.

[0026] Further, the probe body 3, the air inlet pipe 31, and the air outlet pipe 32 are all of a double-layer structure, which includes an inner layer 6 and an outer layer 5. The inner layer 6 is formed of a ceramic material, and the outer layer 5 is formed of a heat-resistant carbon-carbon-based ceramic material.

[0027] A melt on-line detection device based on LIBS technology adopts the above-mentioned melt immersion probe based on LIBS technology. It further includes a rear-end console 1 and a sensing unit. The rear-end control platform 1 is electrically connected to the sensing unit; the sensing unit includes a box body 2 and an optical system provided in the box body. The bottom of the box body 2 is connected to the top of the probe body 3. An opening corresponding to the top opening of the probe body 3 is provided at the bottom of the box body 2, and an optical window 25 is provided at the connection between the opening at the bottom of the box body 2 and the top opening of the probe body 3.

[0028] Further, the box body 2 is of a double-layer structure, which includes an inner layer 6 and an outer layer 5. The inner layer 6 is formed of a ceramic material, and the outer layer 5 is formed of a heat-resistant carbon-carbon-based ceramic material. The box body 2 and the probe body 3 can be integrally formed or separately formed. Of course, separately forming is more conducive to later maintenance and replacement of components, or applying each component to experiments in other fields.

[0029] There can be various optical systems, and it only needs to meet the requirement of generating plasma by laser-exciting and ablating the molten liquid metal to be measured, and then detecting and measuring the composition of the molten liquid metal to be measured by using the emission spectrum of the plasma.

[0030] Furthermore, the optical system includes a laser generator, a beam expanding and focusing module, a remote signal collection module, a fiber optic coupling module, and a fiber optic spectrometer. The fiber optic spectrometer is electrically connected to the backend control platform. The laser generator emits a laser beam, which is focused by the beam expanding and focusing module and reaches the small hole at the bottom end of the probe body, ablating the molten liquid metal to be measured to generate plasma. The plasma cools and expands under the induction of the laser to emit signal light. The signal light of the plasma is transmitted to the remote signal collection module, and then coupled by the fiber optic coupling module and imported into the fiber optic spectrometer. When in use, the melt immersion probe extends into the metallurgical furnace 4 at any angle, and its bottom end passes through the slag layer 41 on the surface of the molten liquid metal in the metallurgical furnace 4 and immerses into the molten liquid metal 42 to be measured. Inert gas is filled into the air inlet pipe 32, and the air in the probe body 3 flows out from the air outlet pipe 31, so as to form a sealed inert gas environment in the probe body 3. The backend control platform 1 controls the laser generating module 21 to emit a laser beam, which is focused by the remote beam expanding and focusing module 22 and then reaches the small hole 34 at the bottom end of the probe body 3 through the optical window 25, ablating the molten liquid metal 42 to be measured to generate plasma. The plasma cools and expands under the induction of the laser to emit signal light. The signal light of the plasma is transmitted to the remote signal collection module 26 through the inert gas environment in the probe body 3, and then transmitted to the fiber optic coupling module 28 for coupling and then imported into the fiber optic spectrometer 29 for optical signal acquisition and optoelectronic conversion, and fed back to the backend control platform 1 to complete the acquisition of the plasma signal light.

[0031] Further, the optical system further includes a first mirror 23 and a second mirror 24. The axis direction of the laser beam emitted by the laser generation module 21 is coaxially arranged with the remote beam expander and focusing module 22. The first mirror 23 is arranged on the optical axis in the emission direction of the remote beam expander and focusing module 22, forming a 45-degree angle with its optical axis. The second mirror 24 is arranged on the optical axis in the incident direction of the remote signal collection module 26, forming a 45-degree angle with its optical axis. The central connection line between the first mirror 23 and the second mirror 24 is perpendicular to the optical axes of the remote beam expander and focusing module 22 and the remote signal collection module 26. A fiber optic coupling module 28 is arranged on the optical axis in the emission direction of the remote signal collection module 26. The fiber optic coupling module 28 is connected to a fiber optic spectrometer 29 through an optical fiber, and the fiber optic spectrometer 29 is electrically connected to the backend control platform 1. During use, the melt immersion probe extends into the metallurgical furnace 4 at any angle, and its bottom end passes through the slag layer 41 on the surface of the molten liquid metal in the metallurgical furnace 4 and immerses into the molten liquid metal 42 to be measured. Inert gas is filled into the intake pipe 32, and the air in the probe body 3 flows out from the exhaust pipe 31, so as to form a sealed inert gas environment in the probe body 3. The backend control platform 1 controls the laser generation module 21 to emit a laser beam, which is focused by the remote beam expander and focusing module 22 and then irradiated onto the first mirror 23. The reflected laser beam passes through the second mirror 24, and then reaches the small hole 34 at the bottom end of the probe body 3 after passing through the optical window 25, ablating the molten liquid metal 42 to be measured to generate plasma. The plasma cools and expands under the induction of the laser to emit signal light. The signal light of the plasma is transmitted to the remote signal collection module 26 through the inert gas environment in the probe body 3, and then transmitted to the fiber optic coupling module 28 for coupling and then introduced into the fiber optic spectrometer 29 for optical signal acquisition and optoelectronic conversion, and fed back to the backend control platform 1 to complete the acquisition of the plasma signal light.

[0032] Further, the optical system further includes a real-time imaging module 20 and a beam splitter 27. The beam splitter 27 is arranged between the remote signal collection module 26 and the fiber optic coupling module 28 and is on the optical axis in the emission direction of the remote signal collection module 26. The real-time imaging module 20 is vertically arranged on the optical axis in the reflection direction of the beam splitter 27 and is electrically connected to the backend control platform 1. The real-time imaging module 20 receives a part of the signal light and the scene background light reflected by the beam splitter 27 and feeds back to the backend control platform 1 to display the state of the molten liquid metal 42 at the small hole 34 of the melt immersion probe and the stability of the plasma formation in real time.

[0033] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A melt immersion probe based on LIBS technology, which comprises a probe body. The probe body is in an inverted conical shape, with openings at its top and bottom respectively. An intake pipe and an exhaust pipe are respectively arranged on the side wall of the probe body, and air valves are respectively arranged on the intake pipe and the exhaust pipe. It is characterized in that: The outer periphery of the bottom opening of the probe body contracts towards the axis of the probe body into a hemispherical shape, and a small hole is formed at the axis; The diameter range of the small hole is 1 mm - 5 mm; The probe body, the intake pipe and the exhaust pipe are all of double-layer structure, which includes an inner layer and an outer layer. The inner layer is formed of ceramic material, and the outer layer is formed of high-temperature resistant and heat-insulating carbon-based ceramic material.

2. The melt immersion probe based on LIBS technology according to claim 1, wherein: The diameter of the small hole is 2 mm.

3. An on-line detection device for melt based on LIBS technology, adopting an immersion probe for melt based on LIBS technology described in claim 1 or 2, characterized in that: It further includes a rear-end console and a sensing unit, and the rear-end console is electrically connected to the sensing unit; the sensing unit includes a box body and an optical system arranged in the box body. The bottom of the box body is connected to the top end of the probe body. An opening corresponding to the top opening of the probe body is provided at the bottom of the box body, and an optical window is provided at the connection between the opening at the bottom of the box body and the top opening of the probe body.

4. The on-line detection device for melt based on LIBS technology according to claim 3, characterized in that: The box body is of double-layer structure, which includes an inner layer and an outer layer. The inner layer is formed of ceramic material, and the outer layer is formed of high-temperature resistant and heat-insulating carbon-based ceramic material.

5. The on-line detection device for melt based on LIBS technology according to claim 3, characterized in that: The optical system includes a laser generator, a beam expander and focusing module, a remote signal collection module, a fiber optic coupling module and a fiber optic spectrometer. The fiber optic spectrometer is electrically connected to the rear-end control platform. The laser generator emits a laser beam, which is focused by the beam expander and focusing module and reaches the small hole at the bottom end of the probe body, ablating the molten liquid metal to be measured to generate plasma. The plasma cools and expands under the induction of the laser to emit signal light. The signal light of the plasma is transmitted to the remote signal collection module, and then coupled by the fiber optic coupling module and then introduced into the fiber optic spectrometer.

6. The on-line detection device for melt based on LIBS technology according to claim 5, characterized in that: The optical system further includes a first reflector and a second reflector. The axis direction of the laser beam emitted by the laser generation module is coaxially arranged with the remote beam expander and focusing module; the first reflector is arranged on the optical axis in the emission direction of the remote beam expander and focusing module, forming a 45-degree angle with its optical axis. The second reflector is arranged on the optical axis in the incident direction of the remote signal collection module, forming a 45-degree angle with its optical axis. The central connection line between the first reflector and the second reflector is perpendicular to the axes of the remote beam expander and focusing module and the remote signal collection module; a fiber optic coupling module is arranged on the optical axis in the emission direction of the remote signal collection module. The fiber optic coupling module is connected to the fiber optic spectrometer through an optical fiber, and the fiber optic spectrometer is electrically connected to the rear-end control platform.

7. The on-line detection device for melt based on LIBS technology according to claim 6, characterized in that: The optical system further includes a real-time imaging module and a beam splitter. The beam splitter is arranged between the remote signal collection module and the fiber optic coupling module and is on the optical axis in the emission direction of the remote signal collection module. The real-time imaging module is vertically arranged on the optical axis in the reflection direction of the beam splitter and is electrically connected to the rear-end control platform.

8. A detection method of an on-line detection device for melt based on LIBS technology, which is applied to an on-line detection device for melt based on LIBS technology as described in claim 5, and is characterized in that: It includes the following steps: The melt immersion probe extends into the metallurgical furnace at any angle, and its bottom end passes through the slag layer on the surface of the molten liquid metal in the metallurgical furnace and immerses into the molten liquid metal to be measured. Inert gas is filled into the intake pipe, and the air in the probe body flows out from the exhaust pipe, so as to form a closed inert gas environment in the probe body; The backend control platform controls the laser generation module to emit a laser beam, which is focused by the remote beam expander and focusing module and reaches the small hole at the bottom of the probe body through the optical window, ablating the molten liquid metal to be measured to generate plasma. The plasma cools and expands under laser induction to emit signal light. The signal light of the plasma is transmitted through the inert gas environment in the probe body to the remote signal collection module, and then transmitted to the fiber optic coupling module for coupling and then imported into the fiber optic spectrometer for optical signal acquisition and optoelectronic conversion, and fed back to the backend control platform to complete the acquisition of the plasma signal light.

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