A material detection system and method

Abstract

The embodiment of the application discloses a kind of material detection system and method, the system includes: carrier gas supply part, for providing and material powder mixing carrier gas;Material supply part, for supplying material at predetermined rate; Gas-solid mixing part is formed by the cavity that is contracted from top to bottom, the upper part of cavity is connected carrier gas supply part and material supply part, for receiving carrier gas provided from carrier gas supply part and material powder provided by material supply part, to mix in the cavity inside and form the material powder of gas-solid two-phase flow form, and eject material powder in the lower part of cavity;Light source, for generating laser pulse;Detection part receives the optical spectrum signal emitted by plasma and detects the composition of material powder.The technical scheme provided by the application improves the probability of laser pulse penetrating powder particles, combined with the dynamic proportioning of carrier gas and the closed-loop self-cleaning control timing, under the premise of meeting the real-time of online detection, improves the stability of long-term online operation of the system and the detection efficiency of material powder.

Description

Technical Field

[0001] This application relates to the field of product testing technology, specifically a material testing system and method. Background Technology

[0002] In the production and quality control processes of industries such as coal, metallurgy, and chemicals, real-time, online, and rapid detection of the composition of powdered materials (such as coal powder, ore powder, and cement raw materials) is of great significance for optimizing production processes, ensuring product quality, and achieving process control. LIBS (Laser-Induced Breakdown Spectroscopy) technology has become a research hotspot in the field of online detection of powdered materials due to its advantages such as requiring no complex sample pretreatment, enabling simultaneous multi-element analysis, and high analysis speed.

[0003] Applying LIBS technology directly to online detection of powder materials presents two main technical challenges. While powder compaction provides a stable detection surface, the sample preparation process is time-consuming and labor-intensive, failing to meet the requirements for real-time online detection. Furthermore, when directly exciting freely falling or accumulated powder with LIBS, the extremely sparse and random spatial distribution of powder particles causes the laser pulse to frequently penetrate air gaps rather than effectively penetrate the powder particles, resulting in a low effective acquisition rate of the spectral signal and low detection efficiency.

[0004] In view of this, this application proposes a material detection system and method to alleviate the above-mentioned technical problems. Summary of the Invention

[0005] Therefore, the purpose of this application is to provide a material detection system and method that improves detection efficiency while meeting the requirements of real-time online detection.

[0006] According to some embodiments, a first aspect of this application provides a material detection system, comprising: a carrier gas supply unit for providing carrier gas for mixing with material powder; a material supply unit for supplying material at a predetermined rate; the material supply unit includes a sampling tank and a vibration device, the sampling tank for storing the material powder to be detected, and the vibration device being installed on a pipe connected to the sampling tank and controlling the supply rate of the material powder by vibration frequency; a gas-solid mixing unit, formed as a cavity that contracts from top to bottom, the upper part of the cavity being connected to the carrier gas supply unit and the material supply unit, for receiving the carrier gas provided by the carrier gas supply unit and the material powder provided by the material supply unit, to mix the material powder in a gas-solid two-phase flow state inside the cavity, and to spray the material powder at the lower part of the cavity; a light source for generating laser pulses to excite the material powder sprayed below the gas-solid mixing unit and generate a plasma spectral signal; and a detection unit for receiving the spectral signal emitted by the plasma and detecting the composition of the material powder.

[0007] In one embodiment, it further includes: a negative pressure recovery unit disposed below the gas-solid mixing unit, used to generate negative pressure suction force to apply suction constraint to the material powder to form a continuous material powder particle flow; the negative pressure recovery unit includes a powder inlet and a suction and collection device; the powder inlet is located below the cavity nozzle and is used to receive the detected material powder; the suction and collection device is used to generate negative pressure suction force at the powder inlet.

[0008] In one embodiment, the carrier gas supply unit further includes: at least one carrier gas storage device for supplying carrier gas to the cavity of the gas-solid mixing unit; and a heating module for heating the carrier gas.

[0009] In one embodiment, the device further includes a control unit electrically connected to a vibration device for controlling the vibration frequency of the vibration device; the control unit electrically connected to an electronically controlled proportional valve for adjusting the output of the electronically controlled proportional valve to control the flow rate and proportion of the carrier gas supply, the electronically controlled proportional valve being disposed on the carrier gas storage device; the control unit electrically connected to a heating module for controlling the heating module to heat the pipeline to adjust the temperature of the carrier gas; the control unit electrically connected to a light source for triggering the light source to generate laser pulses; the control unit electrically connected to a detection unit for acquiring and analyzing spectral signals; and the control unit electrically connected to a suction and dust collection device for controlling the operation of the suction and dust collection device.

[0010] In one embodiment, the control unit is further configured to: control the heating module to heat the carrier gas to a preset temperature; control the electronically controlled proportional valve to output the carrier gas according to a preset ratio; control the vibration frequency of the vibration device to adjust the supply rate of the material powder; start the suction and powder collection device to suction the gas-solid two-phase flow material powder ejected from the nozzle of the cavity; trigger the light source to generate a laser pulse, and simultaneously trigger the detection unit to collect the spectral signal transmitted by the optical transmission device; analyze the spectral signal to obtain the composition of the material powder.

[0011] In one embodiment, the control unit is further configured to: activate the suction and powder collection device at a first moment T0 to establish a negative pressure environment with a preset vacuum degree at the powder inlet; and control the electronically controlled proportional valve to output carrier gas according to a preset ratio after the first moment T0 or after a preset first delay Δt1, and control the heating module to heat the carrier gas to a preset temperature to establish a high-temperature gas jet in the cavity.

[0012] In one embodiment, the control unit is further configured to: after the high-temperature gas jet continues for a second time delay Δt2, at a second time T1, control the vibration frequency of the vibration device so that the material powder in the sampling tank falls into the cavity at a predetermined rate; after the material powder is mixed with the high-temperature gas jet, under the action of the gradually shrinking cross-sectional area structure from the upper to the lower part of the cavity and the negative pressure environment of the powder inlet, a continuous flow of material powder particles is formed below the nozzle.

[0013] In one embodiment, the control unit is further configured to: trigger the light source to generate a laser pulse at a third time T2; the laser pulse is directed towards the nozzle below the nozzle through an optical transmission device to form a continuous flow of material powder particles to form plasma; the spectral signal emitted by the plasma is transmitted to the detection unit through the optical transmission device, and the detection unit captures and collects the spectral signal within a set integration time ΔT.

[0014] In one embodiment, the control unit is further configured to: control the vibration device to stop working at the fourth time T3; and control the electronically controlled proportional valve, heating module and suction powder collection device to continue working for a third time delay Δt3.

[0015] In one embodiment, the control unit is further configured to: control the heating module to start before controlling the electronically controlled proportional valve to output carrier gas, so as to establish a preheating environment in the pipeline and cavity; and control the electronically controlled proportional valve to output carrier gas according to a preset ratio after the preset temperature is reached in the pipeline and cavity, so as to form a high-temperature carrier gas jet.

[0016] In one embodiment, the carrier gas supplied by the carrier gas supply unit is a mixture of inert gas and compressed air; the control unit is further configured to adjust the electronically controlled proportional valve so that the volume ratio of inert gas in the mixture is not less than 30%, and to control the flow rate of the mixture within the range of 5-15 m / s, so that the material powder forms a fully dispersed turbulent mixing state in the cavity, and then accelerates its fall through the gradually narrowing structure of the cavity.

[0017] In one embodiment, the control unit is further configured to adjust the electronically controlled proportional valve according to the moisture content or particle size of the material powder to adjust the ratio of inert gas to compressed air in the mixed gas.

[0018] According to some embodiments, a second aspect of this application provides a material detection method using the material detection system provided in the first aspect of this application, comprising: starting a heating module to preheat the pipes and cavity, and then introducing a carrier gas to form a high-temperature drying gas; introducing material powder, using the high-temperature drying gas to dry the material powder online, and detecting it; stopping the supply of material powder, maintaining a continuous supply of high-temperature drying gas and continuous suction of the negative pressure recovery unit, and performing high-temperature purging and recovery of the gas-solid mixing unit, the light source, and the detection unit to achieve self-cleaning.

[0019] The embodiments disclosed herein have at least the following advantages: the carrier gas and the material powder are mixed inside the cavity to form a gas-solid two-phase flow of the material powder. The cross-sectional area of ​​the cavity gradually shrinks from top to bottom. The gradually shrinking structure accelerates and initially constrains the mixed gas-solid two-phase flow, and gathers and constrains the particle flow ejected from the cavity, limiting its radial diffusion and forming a high-density, small-section stable particle flow. This increases the probability of laser pulses breaking down powder particles and improves the effective acquisition rate of spectral signals, thereby improving detection efficiency while meeting the real-time requirements of online detection. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall logic of a material detection system according to an embodiment of this application; Figure 2 This is a schematic diagram of the connection relationship of a material detection system according to an embodiment of this application; Figure 3 This is a schematic diagram of a material testing method according to an embodiment of this application.

[0021] Figure label: 1: Pear-shaped cavity; 2: Inert gas storage device; 3: Compressed air storage device; 4: Electrically controlled proportional valve; 5: Gas delivery pipe; 6: Sealing plug; 7: Sample placement groove; 8: Vibration device; 9: Laser; 10: Dichroic mirror; 11: Laser focusing lens; 12: Light-collecting focusing lens; 13: Light-collecting fiber; 14: Grating spectrometer; 15: Powder inlet; 16: Powder suction and collection device; 17: Control unit; 18: Heating module. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0023] The accompanying drawings illustrate layer structure diagrams according to embodiments of this application. These drawings are not necessarily drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0024] Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The application will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are represented by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0025] Figure 1 This is a schematic diagram of the overall logic of a material detection system according to an embodiment of this application; Figure 2 This is a schematic diagram of the connection relationship of a material detection system according to an embodiment of this application.

[0026] refer to Figure 1 and Figure 2 The material detection system provided in this application includes: a carrier gas supply unit, a material supply unit, a light source, a gas-solid mixing unit, and a detection unit.

[0027] The carrier gas supply unit is used to provide carrier gas for mixing with the material powder. The material supply unit is used to supply material at a predetermined rate; it includes a sampling tank 7 and a vibration device 8. The sampling tank 7 is used to store the material powder to be tested, and the vibration device 8 is installed on a pipe connected to the sampling tank 7 and controls the supply rate of the material powder by the vibration frequency.

[0028] The gas-solid mixing section is formed as a cavity that contracts from top to bottom. The upper part of the cavity is connected to the carrier gas supply section and the material supply section through a pipe. It is used to receive the carrier gas provided by the carrier gas supply section and the material powder provided by the material supply section, so as to mix the material powder in the cavity to form a gas-solid two-phase flow state. The cross-sectional area of ​​the cavity gradually contracts from the upper part to the lower part, and a nozzle is formed at the lower end to spray the material powder.

[0029] A light source is used to generate laser pulses, which excite the material powder ejected below the gas-solid mixing section and generate a plasma spectral signal. Exemplarily, the light source may be a laser 9, which generates laser pulses that are directed through an optical transmission device towards a high-density continuous flow of material powder particles below the nozzle to form plasma.

[0030] For example, the cavity can be as follows Figure 2 The pear-shaped cavity 1 shown has a cross-sectional area that gradually shrinks from top to bottom, eventually forming a finer nozzle at the bottom.

[0031] The detection unit receives the spectral signal emitted by the plasma and detects the composition of the material powder. For example, the detection unit includes a grating spectrometer 14; the spectral signal emitted by the plasma is transmitted to the grating spectrometer 14 via an optical transmission device, and the spectral signal is acquired by the grating spectrometer 14 and used to detect the composition of the material powder.

[0032] For example, the optical transmission device can be as follows: Figure 2 The diagram shows a dichroic mirror 10, a laser focusing lens 11, a light-collecting focusing lens 12, and a light-collecting fiber 13. The horizontal beam emitted by the laser 9 passes through the dichroic mirror 10 and is focused by the laser focusing lens 11 onto the powder stream directly below the nozzle at the bottom of the pear-shaped cavity 1. The high-energy laser pulse is focused into the central region of the powder particle stream, generating plasma. The same-direction spectral signal emitted by the plasma is transmitted through the laser focusing lens 11 and the dichroic mirror 10, coupled through the light-collecting focusing lens 12 into the light-collecting fiber 13, and transmitted to the grating spectrometer 14.

[0033] It should be noted that in existing technologies, the particle number density of freely falling or simply blown-away powder is extremely low and randomly distributed in space. The laser's focus is difficult to consistently hit the particles, resulting in a very low effective spectral signal rate, which cannot meet the requirements for continuous and stable online detection. This embodiment achieves accelerated falling of the powder and plasticity of the powder flow shape by gradually narrowing the cross-sectional area of ​​the cavity from top to bottom, thereby forming a stable, high-density powder flow and improving detection efficiency.

[0034] In one embodiment, this application further includes: a negative pressure recovery section disposed below the gas-solid mixing section, used to generate negative pressure suction force to apply suction constraint to the material powder to form a continuous material powder particle flow; it includes a powder inlet 15 and a suction and powder collection device 16; the powder inlet 15 is located below the nozzle of the cavity and is used to receive the detected material powder; the suction and powder collection device 16 is used to generate negative pressure suction force at the powder inlet, and the negative pressure suction force works in conjunction with the gradually narrowing structure of the cavity to form suction constraint on the material powder ejected from the nozzle, so as to form a continuous material powder particle flow with suppressed radial diffusion, high density and stable cross-section between the nozzle and the powder inlet.

[0035] It should be noted that after the material powder detection is completed, residual powder easily deposits on the surfaces of pipelines and optical components, affecting the accuracy of subsequent measurements and increasing the maintenance burden on the equipment during long-term operation. Furthermore, laser ablation and the airflow introduced to form the powder stream can easily cause powder to splatter everywhere in the open environment. Long-term operation will severely contaminate optical transmission devices such as the dichroic mirror 10, laser focusing lens 11, and light-collecting focusing lens 12, leading to rapid system signal attenuation, high maintenance costs, and poor stability.

[0036] In this embodiment, a powder inlet 15 and a suction powder collection device 16 are configured below the nozzle of the cavity. When detecting material powder, the negative pressure environment generated by the suction powder collection device 16 is used to recover the residual material powder, thus avoiding the powder from easily depositing on the surface of pipelines and optical devices.

[0037] More importantly, the powerful suction at the bottom not only recovers the dust but also establishes a downward fluid pressure gradient in the laser target area, restricting the lateral disordered movement of powder particles. This results in a smaller cross-sectional area of ​​the powder flow and a sharp increase in particle number density. The acceleration of the material powder by the cavity shape, along with the negative pressure "convergence" effect formed at the bottom, together create a stable, high-density powder particle flow. This ensures the intensity and stability of the spectral signal from the source, thereby significantly improving the spectral efficiency and signal-to-noise ratio of continuous material powder measurements.

[0038] In one embodiment, the carrier gas supply unit further includes: at least one carrier gas storage device for supplying carrier gas to the cavity of the gas-solid mixing unit; and a heating module for heating the carrier gas.

[0039] For example, the carrier gas supply unit includes at least one of inert gas or compressed air carrier gas storage device; the carrier gas storage device supplies carrier gas to the cavity of the gas-solid mixing unit through a pipe equipped with a heating module 18; the carrier gas storage device is equipped with an electronically controlled proportional valve 4 to control the flow rate and proportion of the carrier gas supply.

[0040] In existing technologies, the carrier gas environment has poor adaptability, especially lacking the ability to handle moisture. Existing equipment typically only provides a single carrier gas or protective gas channel, making it difficult to flexibly switch or handle the carrier gas environment according to the material characteristics. For high-moisture materials, there is a lack of effective means to suppress the quenching effect of moisture on plasma, leading to distorted or invalid detection results.

[0041] For example, refer to Figure 2 The inert gas storage device 2 and the compressed air storage device 3 enter the pear-shaped cavity 1 vertically downwards through the top sealing plug 6 via the electronically controlled proportional valve 4 and the gas delivery pipe 5. A heating module 18 is connected in series on the gas delivery pipe 5 to preheat the gas entering the cavity.

[0042] The gas-introduced heating module 18 continuously transfers heat to the powder during the initial flow field establishment and measurement process, effectively removing moisture from high-moisture materials before they reach the plasma region. When the laser focus hits the high-density, low-moisture confined particle stream, the laser energy is efficiently used to excite sample atoms, rather than being consumed by moisture vaporization and plasma quenching, thus ensuring extremely high spectral efficiency and signal intensity from a physical mechanism perspective.

[0043] This embodiment combines the heating module 18 with the pear-shaped cavity 1 and the bottom suction powder collection device 16, forming a synergistic system and a "thermal-gas-mechanical" coupled powder particle flow density constraint and pretreatment method. The pear-shaped cavity 1, through its configuration, densifies and accelerates the flow of the powder material. The high-temperature carrier gas not only provides power but also dries the powder online during the flow field establishment phase, solving the problem of plasma quenching caused by high-moisture materials. The preheating function of the heating module 18 is extended to the shutdown phase, using high-temperature airflow to perform delayed purging of the entire system, especially near the optical path and pipelines, and the suction powder collection device 16 for extraction and recovery. This effectively solves the problems of powder deposition, agglomeration, and residue, achieving self-maintenance within the detection cycle and significantly improving the long-term operational stability and reliability of the system.

[0044] In one embodiment, this application further includes a control unit 17, which is electrically connected to a vibration device 8 and used to control the vibration frequency of the vibration device 8; the control unit 17 is electrically connected to an electronically controlled proportional valve 4 and used to adjust the output of the electronically controlled proportional valve 4 to control the flow rate and proportion of the carrier gas supply, the electronically controlled proportional valve 4 being disposed on the carrier gas storage device; the control unit 17 is electrically connected to a heating module 18 and used to control the heating module to heat the pipeline to adjust the temperature of the carrier gas; the control unit 17 is electrically connected to a laser 9 and used to trigger the laser to generate laser pulses; the control unit 17 is electrically connected to a grating spectrometer 14 and used to acquire and analyze spectral signals; the control unit 17 is electrically connected to a suction and dust collection device 16 and used to control the operation of the suction and dust collection device.

[0045] For example, refer to Figure 2 The control unit 17 can be an industrial computer, which is electrically connected to the electronically controlled proportional valve 4, the vibration device 8, the laser 9, the grating spectrometer 14, the suction and powder collection device 16, and the heating module 18.

[0046] In one embodiment, the control unit 17 is further configured to: control the heating module 18 to heat the carrier gas to a preset temperature; control the electronically controlled proportional valve 4 to output the carrier gas according to a preset ratio; control the vibration frequency of the vibration device 8 to adjust the supply rate of the material powder; start the suction and collection device 16 to suction the gas-solid two-phase flow material powder ejected from the nozzle of the cavity; trigger the laser 9 to generate a laser pulse, and synchronously trigger the grating spectrometer 14 to collect the spectral signal transmitted by the optical transmission device; analyze the spectral signal to obtain the composition of the material powder.

[0047] For example, the control unit 17 activates the heating module 18 to preheat the carrier gas to a set temperature according to the characteristics of the material to be tested, such as a preset moisture content parameter. Simultaneously, the vibration device 8 and the electronically controlled proportional valve 4 are activated to adjust the vibration frequency, controlling the falling rate of the powder material in the sampling tank 7, and outputting inert gas or compressed air according to a preset ratio. The preheated gas mixes with the powder in the pear-shaped cavity 1. The hot gas rapidly preheats and dries the powder during convection, effectively reducing the moisture content of the material. The mixed gas-solid two-phase flow forms an initial jet under the acceleration of the cavity's tapering structure. Simultaneously, the suction and powder collection device 16 is activated, generating negative pressure at the powder inlet 15. Under the combined action of gravity, the upward airflow thrust, and the downward suction force, the powder is ejected from the bottom of the cavity, and its radial diffusion is effectively suppressed, forming a high-density, small-diameter, dehydrated powder particle stream.

[0048] The control unit 17 triggers the laser 9, and the high-energy laser pulse is focused onto the central region of the powder particle flow to generate plasma. When the laser 9 emits the pulsed laser, it simultaneously triggers the grating spectrometer 14 to collect the same-direction spectral data transmitted through the dichroic mirror 10.

[0049] The waste material powder and unreacted material powder after the reaction are completely sucked into the suction and collection device 16 by the powder inlet 15; the control unit 17 processes the spectral data and outputs the material powder composition information.

[0050] In one embodiment, the control unit 17 is further configured to: activate the suction and powder collection device at a first moment T0 to establish a negative pressure environment with a preset vacuum degree at the powder inlet 15; and after the first moment T0 or after a preset first delay Δt1, control the electronically controlled proportional valve 4 to output carrier gas according to a preset ratio, and control the heating module to heat the carrier gas to a preset temperature to establish a high-temperature gas jet in the cavity.

[0051] For example, the first moment T0 can be the system startup moment T0. The control unit 17 first sends a start signal to the suction and powder collection device 16, so that it establishes a negative pressure environment with a preset vacuum degree at the powder inlet 15. Synchronously, after the first moment T0 or after the first delay Δt1, the control unit 17 sends a control command to the electronically controlled proportional valve 4 to introduce gas at a set flow rate, and sends a command to the heating module 18 to heat the gas to a preset temperature, so as to establish a downward high-temperature gas jet in the pear-shaped cavity 1.

[0052] In one embodiment, the control unit 17 is further configured to: after the high-temperature gas jet continues for a second time delay Δt2, at a second time T1, control the vibration frequency of the vibration device 8 so that the material powder in the sampling tank 7 falls into the cavity at a predetermined rate; after the material powder is mixed with the high-temperature gas jet, under the synergistic effect of the gradually shrinking cross-sectional area structure from the upper to the lower part of the cavity and the negative pressure environment of the powder inlet 15, a high-density continuous material powder particle flow with suppressed radial diffusion is formed below the nozzle.

[0053] For example, after the high-temperature gas jet continues for a second time delay Δt2, that is, the system maintains no-load operation for a period of time Δt2, for example, Δt2 is 2-5 seconds. This serves as a flow field stabilization buffer period to ensure that the suction constraint aerodynamic flow field inside the cavity and at the bottom reaches dynamic equilibrium, thus avoiding turbulent speckle when subsequent powder enters.

[0054] At the second moment T1 after the flow field stabilizes, the control unit 17 outputs a vibration adjustment signal or voltage control signal to the vibration device 8 to start the feeding program of the sampling tank 7. After the powder material enters the pear-shaped cavity 1, it is fully mixed with the preheated high-temperature gas, and rapid heat exchange occurs. The moisture in the material is evaporated and carried out with the airflow. The control unit 17 maintains the stable operation of the electronically controlled proportional valve 4 and the suction powder collection device 16, so that the dried material powder forms a continuous and stable flow of powder material particles with extremely small diameter and extremely high density in the laser target area under the dual action of the contraction port at the bottom of the cavity and the negative pressure below.

[0055] In one embodiment, the control unit 17 is further configured to: trigger the laser to generate a laser pulse at a third time T2; the laser pulse is directed below the nozzle through an optical transmission device to form a continuous flow of material powder particles to form plasma; the spectral signal emitted by the plasma is transmitted to the grating spectrometer 14 through the optical transmission device; the grating spectrometer 14 captures and collects the spectral signal within a set integration time ΔT.

[0056] For example, at the third time T2, the control unit 17 sends a trigger pulse to the laser 9, emitting a single-pulse high-energy laser to break down the confined particle stream of the powder material currently in the target area. The laser 9 can control the grating spectrometer 14 to perform spectral acquisition via the trigger line, capturing the plasma atomic emission spectrum transmitted in the same direction through the light-collecting focusing lens 12 and the dichroic mirror 10 within the set integration time ΔT.

[0057] In one embodiment, the control unit 17 is further configured to: control the vibration device 8 to stop working at the fourth time T3; and control the electronically controlled proportional valve 4, the heating module 18 and the suction and powder collection device 16 to continue working for a third time delay Δt3.

[0058] It should be noted that the control unit 17 controls the system to repeatedly execute the "excitation-acquisition" process of the laser 9 and the grating spectrometer 14 N times, for example, N can be 100-500 times, and accumulate or average the multiple spectral signals to eliminate the random fluctuations caused by a single pulse and complete a complete sample analysis.

[0059] For example, at the fourth moment T3 after the measurement is completed, the control unit 17 first cuts off the control signal of the vibration device 8 to stop the material powder from entering the cavity. During this stage, the control unit 17 keeps the electronically controlled proportional valve 4 and the heating module 18 in the open state, and maintains the maximum negative pressure operation of the suction and powder collection device 16. A third time delay Δt3 is used to purge the pear-shaped cavity 1, the optical path below the dichroic mirror 10, and the pipeline using a pure, high-temperature airflow. For example, the third time delay Δt3 can be 10 seconds. The high-temperature airflow effectively purges and dries any residual wet powder that may adhere to the pipe wall and inner wall, preventing clumping or adhesion, and achieving thorough online self-cleaning. After confirming that the purging is complete, the control unit 17 sequentially closes the electronically controlled proportional valve 4, the heating module 18, and the suction and powder collection device 16, completing the entire detection and system self-cleaning process.

[0060] In one embodiment, the control unit 17 is further configured to implement a closed-loop thermal management and timing control method. Unlike simply heating the carrier gas, this system uses timing control to extend heating throughout the entire detection cycle, forming a closed loop of "preheating-drying-measurement-high-temperature purging." Specifically, during the startup phase, the control unit 17 first activates the heating module 18 to preheat the gas delivery pipe 5 and the pear-shaped cavity 1 itself, preventing condensation or unstable flow fields from the low-temperature cavity contacting the high-temperature carrier gas. After the preheating environment is established, the carrier gas is then introduced to form a stable high-temperature gas jet. This preheating-then-gas-introduction sequence ensures that from the initial moment, all surfaces and airflow in contact with the material are in a high-temperature, dry state, fundamentally eliminating the possibility of material powder absorbing moisture and agglomerating due to contact with cold walls, and ensuring the stability of the gas-solid two-phase flow pattern.

[0061] In one embodiment, the carrier gas supply unit provides a carrier gas composed of a proportional mixture of inert gas and compressed air, wherein the carrier gas may be argon. The control unit 17 is further configured to adjust the electronically controlled proportional valves 4 for the inert gas and compressed air respectively, ensuring that the volume percentage of inert gas in the mixed gas is not less than 30%, preferably 60%-80%, and controlling the flow velocity of the mixed gas at the cavity inlet within the range of 5-15 m / s. This ratio and flow velocity range represent an experimentally verified balance: the inert gas component provides a stable, low-interference environment for plasma generation, enhancing the spectral signal intensity; while the compressed air component provides sufficient momentum to transport the powder and participate in the oxidation reaction during the drying process. This flow velocity range allows the powder particles to form a fully dispersed state in the larger space at the top of the cavity, achieving sufficient heat exchange and moisture removal between particles and with the hot gas flow, followed by being organized and accelerated into a high-density particle stream by the tapered structure. This process realizes a fluid dynamic transition from "mixed drying" to "confined excitation."

[0062] In one embodiment, the control unit 17 is further configured to dynamically adjust the proportion of the mixed gas according to the characteristics of the powder to be tested. For example, when testing coal powder with high moisture content, the proportion of compressed air can be appropriately increased to enhance the drying effect; when testing air-sensitive metal powder, the proportion of inert gas can be increased to close to 100%.

[0063] Figure 3 This is a schematic diagram of a material testing method according to an embodiment of this application.

[0064] refer to Figure 3 This application provides a material detection method, which uses the material detection system provided in the above embodiments and includes the following steps.

[0065] Step S1: System preheating. At time T0, the control unit 17 first starts the heating module 18 separately to preheat the gas delivery pipe 5, the pear-shaped cavity 1, and its nozzle. No carrier gas or material is introduced during this stage. After preheating for 1-3 seconds, the temperature of the pipeline and cavity reaches the preset value, for example, 90-120℃, eliminating cold spots and residual moisture in the system.

[0066] Step S2: Flow Field Establishment. After preheating, the control unit 17 opens the electronically controlled proportional valve 4, introducing a mixture of inert gas and compressed air according to a preset ratio. At this time, the heated gas flows in the preheated pipeline, resulting in a more stable temperature. The control unit 17 precisely adjusts the opening of the electronically controlled proportional valve 4 to stabilize the flow rate of the mixed gas at a preset value, establishing a stable, dry, high-temperature gas jet within the pear-shaped cavity 1. Simultaneously, the bottom suction and powder collection device 16 begins operation, forming a steady-state negative pressure suction flow field.

[0067] Step S3: Powder feeding and drying. After the flow field stabilizes, the control unit 17 starts the sampling tank 7 with vibration device 8, and the material powder falls into the cavity at a controlled rate. In the turbulent mixing with the high-temperature carrier gas, the moisture of the powder is rapidly removed. Under the synergistic effect of the cavity's tapering structure and the bottom negative pressure, the dried powder forms a high-density, small-cross-section continuous particle stream below the pear-shaped cavity 1.

[0068] Step S4: Measurement. The laser pulse triggered by the control unit 17 can efficiently penetrate the powder particles, and the excited plasma spectral signal is stably acquired by the grating spectrometer 14.

[0069] Step S5: Self-cleaning by purging. After completing the preset number of tests, the control unit 17 controls the vibration device 8 to shut down, stopping the feeding. However, at this time, the heating module 18, the electronically controlled proportional valve 4, and the suction powder collection device 16 all remain running, performing high-temperature purging and recovery on the gas-solid mixing section, the light source, and the detection section to achieve self-cleaning. A continuous high-temperature, pure mixed airflow is formed to purge the entire powder flow path, including the gas-solid mixing section and the light source, specifically the inner wall of the pear-shaped cavity 1, the nozzle, and the area near the laser focusing and light-collecting optical path. The residual and scattered powder purged out is efficiently recovered by the powder receiving port 15 at the bottom under negative pressure. This process lasts for 5-15 seconds, ensuring that the inside of the system is clean and dry.

[0070] Step S6: Determine whether to continue testing. Based on the testing task or system instructions, determine whether to proceed to the next testing cycle. If testing needs to continue, repeat steps S1 to S5. If testing is complete, the control unit 17 sequentially closes the electronically controlled proportional valve 4 and the heating module 18, and finally delays the shutdown of the suction and powder collection device 16 to ensure that all suspended particles have settled and been recovered. This completes a full online testing cycle including self-cleaning functionality.

[0071] Through the aforementioned closed-loop process, this system upgrades traditional single-point discrete measurement into a fully automated solution that includes environmental preparation, material preprocessing, signal enhancement, and automatic maintenance.

[0072] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this application and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this application should be included within the protection scope of this application. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A material detection system, characterized in that, include: Carrier gas supply unit, used to provide carrier gas for mixing with material powder; A material supply unit for supplying materials at a predetermined rate; it includes a sampling tank and a vibration device, wherein the sampling tank is used to store the material powder to be tested, and the vibration device is installed on a pipe connected to the sampling tank and controls the supply rate of the material powder by the vibration frequency. The gas-solid mixing section is formed as a cavity that contracts from top to bottom. The upper part of the cavity is connected to the carrier gas supply section and the material supply section. It is used to receive the carrier gas provided by the carrier gas supply section and the material powder provided by the material supply section, so as to mix the material powder in the cavity to form a gas-solid two-phase flow pattern, and spray the material powder at the lower part of the cavity. A light source is used to generate laser pulses to excite the material powder ejected below the gas-solid mixing section and generate plasma spectral signals; The detection unit receives the spectral signal emitted by the plasma and detects the composition of the material powder.

2. The material detection system according to claim 1, characterized in that, Also includes: A negative pressure recovery unit is located below the gas-solid mixing unit and is used to generate negative pressure suction force to apply suction constraint to the material powder to form a continuous material powder particle flow. The negative pressure recovery unit includes a powder receiving port and a suction and powder collection device. The powder receiving port is located below the cavity nozzle and is used to receive the detected material powder. The suction and powder collection device is used to generate negative pressure suction force at the powder receiving port.

3. The material detection system according to claim 2, characterized in that, The carrier gas supply unit also includes: At least one carrier gas storage device is provided for supplying carrier gas to the cavity of the gas-solid mixing section; The heating module is used to heat the carrier gas.

4. The material detection system according to claim 3, characterized in that, It also includes the control unit, The control unit is electrically connected to the vibration device and is used to control the vibration frequency of the vibration device; The control unit is electrically connected to an electronically controlled proportional valve and is used to adjust the output of the electronically controlled proportional valve to control the flow rate and ratio of the carrier gas supply. The electronically controlled proportional valve is configured on the carrier gas storage device. The control unit is electrically connected to the heating module and is used to control the heating module to heat the pipeline in order to regulate the temperature of the carrier gas. The control unit is electrically connected to the light source and is used to trigger the light source to generate laser pulses; The control unit is electrically connected to the detection unit and is used to acquire and analyze spectral signals; The control unit is electrically connected to the suction and dust collection device and is used to control the operation of the suction and dust collection device.

5. The material detection system according to claim 4, characterized in that, The control unit is further configured as follows: The heating module is controlled to heat the carrier gas to a preset temperature, the electronically controlled proportional valve is controlled to output the carrier gas according to a preset ratio, and the vibration frequency of the vibration device is controlled to adjust the supply rate of the material powder. Start the suction and powder collection device to suction the gas-solid two-phase flow material powder sprayed from the cavity nozzle; The light source is triggered to generate a laser pulse, which simultaneously triggers the detection unit to collect the spectral signal transmitted by the optical transmission device; The composition of the material powder is obtained by analyzing the spectral signal.

6. The material detection system according to claim 4, characterized in that, The control unit is further configured as follows: At the first moment T0, the suction and powder collection device is activated to establish a negative pressure environment with a preset vacuum degree at the powder inlet; At the first moment T0 or after a preset first delay Δt1, the electronically controlled proportional valve is controlled to output carrier gas according to a preset ratio, and the heating module is controlled to heat the carrier gas to a preset temperature to establish a high-temperature gas jet in the cavity.

7. The material detection system according to claim 6, characterized in that, The control unit is further configured as follows: After the high-temperature gas jet continues for a second time delay Δt2, at the second time T1, the vibration frequency of the vibration device is controlled so that the material powder in the sampling tank falls into the cavity at a predetermined rate. After the material powder is mixed with the high-temperature gas jet, under the action of the gradually shrinking cross-sectional area structure from the upper to the lower part of the cavity and the negative pressure environment of the powder inlet, a continuous flow of material powder particles is formed below the nozzle of the cavity.

8. The material detection system according to claim 7, characterized in that, The control unit is further configured as follows: At the third moment T2, the light source is triggered to generate a laser pulse. The laser pulse is transmitted through an optical transmission device and directed below the nozzle to form a continuous flow of material powder particles to form the plasma. The spectral signal emitted by the plasma is transmitted to the detection unit through an optical transmission device, and the detection unit captures and collects the spectral signal within a set integration time ΔT.

9. The material detection system according to claim 8, characterized in that, The control unit is further configured as follows: At the fourth time T3, the vibration device is controlled to stop working; the electronically controlled proportional valve, heating module and suction powder collection device are controlled to continue working for a third time delay Δt3.

10. The material detection system according to claim 4, characterized in that, The control unit is further configured as follows: Before controlling the output of carrier gas by the electronically controlled proportional valve, the heating module is started to establish a preheating environment in the pipeline and cavity; After the preset temperature is reached in the pipe and cavity, the electronically controlled proportional valve is controlled to output carrier gas according to a preset ratio to form a high-temperature carrier gas jet.

11. The material detection system according to claim 4, characterized in that, The carrier gas supplied by the carrier gas supply unit is a mixture of inert gas and compressed air; The control unit is further configured to adjust the electronically controlled proportional valve so that the volume ratio of inert gas in the mixed gas is not less than 30%, and to control the flow rate of the mixed gas within the range of 5-15 m / s, so that the material powder forms a fully dispersed turbulent mixing state in the cavity, and then falls more rapidly through the gradually narrowing structure of the cavity.

12. The material detection system according to claim 11, characterized in that, The control unit is further configured to adjust the electronically controlled proportional valve according to the moisture content or particle size of the material powder, so as to adjust the ratio of inert gas to compressed air in the mixed gas.

13. A material detection method, employing the material detection system of claim 10, characterized in that, include: The heating module is activated to preheat the pipes and cavity, and then carrier gas is introduced to form high-temperature dry gas; Material powder is introduced, and the high-temperature drying gas is used to dry the material powder online, followed by detection. Stop supplying the material powder, maintain the continuous supply of the high-temperature drying gas and the continuous suction of the negative pressure recovery unit, and perform high-temperature purging and recovery of the gas-solid mixing unit and the light source to achieve self-cleaning.

Images