Method for detecting particle shape and size of energetic material melt-suspension granulation process

Abstract

This invention discloses a method for detecting particle shape and size during the melt suspension granulation process of energetic materials. The method includes: acquiring droplet images during the heating and dispersion of the energetic material into a dispersion medium; determining droplet size distribution data based on the droplet images; determining whether the droplet size distribution meets the cooling crystallization conditions; if so, proceeding to crystallization; if not, adjusting the stirring rate until the droplet size distribution meets the cooling crystallization conditions; completing the crystallization of the energetic material, acquiring images of the crystalline particles during the crystallization process; determining whether the diameter distribution of the crystalline particles meets the conditions for ending crystallization granulation based on the crystalline particle images; if so, ending the granulation detection; if not, reheating to the melting temperature of the energetic material and re-entering droplet image acquisition until the conditions for ending crystallization granulation are met, ending the detection. This invention achieves real-time dynamic monitoring of the spheroidization process of energetic material melting and crystallization, solving the problem of lag in traditional offline detection.

Description

Technical Field

[0001] This invention belongs to the field of energetic material preparation technology, and relates to particle shape and size detection, and more particularly to a method for detecting particle shape and size during the melt suspension granulation process of energetic materials. Background Technology

[0002] The melt suspension granulation process of energetic materials involves heating the energetic material to a molten state in a high-viscosity dispersion medium (such as silicone oil, DOS, etc.), dispersing it into droplets by stirring, and then cooling and crystallizing it to form particles with specific particle shape and size. The uniformity of droplet size and the final particle diameter distribution directly affect the energy release efficiency and safety of energetic materials in propellants and explosives. Therefore, it is necessary to detect the particle shape and size.

[0003] Existing particle shape and size detection technologies include offline and online detection. Offline detection relies on manual sampling followed by analysis using a laser particle size analyzer or microscope. The time from sampling to result feedback is more than 30 minutes, which cannot capture the dynamic changes of droplets and particles in real time during granulation. This leads to a lag in process parameter adjustment and poor repeatability of particle size in batches of products. Existing online detection methods only focus on the particle size distribution after crystallization and do not cover the real-time monitoring of molten droplet size. However, droplet size directly determines the final particle quality. The lack of this link results in a lack of early data support for process control. Therefore, there is an urgent need to design a particle shape and size detection method suitable for the molten suspension granulation process of energetic materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for detecting particle shape and size during the melting and suspension granulation process of energetic materials, thereby solving the technical problems of detection lag and incomplete detection objects in existing detection methods.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses a method for detecting particle shape and size during the melt suspension granulation process of energetic materials, comprising the following steps:

[0007] Step 1: Add the dispersion medium and energetic material sequentially into the granulation vessel, heat to the melting temperature of the energetic material, and stir at the first stirring rate until the energetic material melts and disperses in the dispersion medium; during the melting and dispersion process of the energetic material, use an industrial camera installed in the granulation vessel to acquire images of the molten droplets of the energetic material at preset time intervals to obtain droplet images;

[0008] Step 2: Determine the droplet size distribution data based on the acquired droplet images. The droplet size distribution data includes Dv10, Dv50, and Dv90.

[0009] Step 3: Determine whether the droplet size distribution meets the cooling crystallization conditions, wherein the cooling crystallization conditions are: Dv50 < first threshold and Dv90-Dv10 < second threshold;

[0010] If so, proceed to step 4;

[0011] If not, increase the stirring rate and continue stirring until the droplet size distribution meets the cooling crystallization conditions, then proceed to step 4;

[0012] Step 4: Cool the granulation vessel to the crystallization temperature of the energetic material to complete the crystallization of the energetic material. During the crystallization process, use an industrial camera inserted into the granulation vessel to collect images of the energetic material crystallized particles at preset time intervals.

[0013] Step 5: Determine whether the diameter distribution of the crystallized particles meets the conditions for ending crystallization based on the collected images of energetic material crystallized particles. The crystallization granulation conditions include: Dv50 < first threshold and Dv90-Dv10 < second threshold.

[0014] If yes, then end the granulation test; if no, reheat to the melting temperature of the energetic material and return to step 2.

[0015] The present invention also has the following technical features:

[0016] Specifically, the solid-liquid ratio of the dispersion medium to the energetic material is 1% to 15%.

[0017] Furthermore, the energetic material includes ammonium nitrate, dinitramide ammonium, and guanidine nitrate.

[0018] Furthermore, the dispersion medium is selected from any one of silicone oil, liquid paraffin oil, toluene, cyclohexane, dodecane, hexadecane, styrene, and dioctyl sebacate.

[0019] Furthermore, the first stirring rate mentioned in step 1 is 200 r / min to 400 r / min.

[0020] Furthermore, the time interval mentioned in step 1 is 10 to 12 seconds.

[0021] Furthermore, the first threshold mentioned in steps 3 and 5 is 400 μm, and the second threshold is 200 μm.

[0022] Furthermore, the time interval described in step 4 is 15-20 seconds.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) The method of the present invention realizes real-time dynamic monitoring of the melting and crystallization spheroidization process of energetic materials, solves the problem of lag in traditional offline detection, shortens the detection response time to less than 30 seconds, and significantly improves the detection efficiency.

[0025] (2) The method of the present invention has been optimized for high-temperature melting of energetic materials and high-viscosity fluids as dispersion media and explosion-proof requirements, effectively overcoming the influence of high-viscosity fluid adhesion, high temperature and liquid-solid phase change on detection accuracy.

[0026] (3) The method of the present invention breaks through the limitation of the prior art which only focuses on the particles after crystallization. For the first time, it covers the size detection of molten droplets. By controlling the uniformity of droplets, it solves the problem of uneven particle size distribution of energetic materials from the source.

[0027] Other advantages of the present invention will be described in detail in the specific embodiments. Attached Figure Description

[0028] Figure 1 This is a graph showing the droplet size distribution variation obtained in Example 1;

[0029] Figure 2 These are droplet images acquired in Example 1;

[0030] Figure 3 These are images of crystalline particles collected in Example 1. Detailed Implementation

[0031] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0032] Unless otherwise specified, the raw materials and components (such as industrial cameras and granulation kettles) used in this invention are all commercially available.

[0033] Example 1

[0034] Following the above technical solution, this embodiment discloses a method for detecting particle shape and size during the melt suspension granulation process of energetic materials, which detects the particle shape and size of ammonium dinitramide (ADN) during melt suspension granulation in 500cSt silicone oil, including the following steps:

[0035] Step 1: Add 5g of energetic material ADN to 800mL of dispersion medium (500cSt silicone oil) in a granulation vessel, heat to the melting temperature of 100℃, and stir at a stirring rate of 300r / min to completely melt and disperse the energetic material in the 500cSt silicone oil. During the dispersion process, use an industrial camera inserted into the granulation vessel to acquire images of the molten energetic material droplets at preset 10s intervals, obtaining multiple images such as... Figure 2 The droplet image shown;

[0036] In this embodiment, an industrial camera is installed inside the probe, which has a transparent window through which the camera can take pictures. The probe body is made of Hastelloy C-276, the transparent window is made of 2mm sapphire glass, and the inner surface is coated with a 5μm Teflon coating. The industrial camera is an intrinsically safe CMOS camera (1 / 1.8-inch target surface, minimum exposure time 0.03ms), and the light source is a 520nm LED (600lux brightness). The probe is vertically installed on the side wall of a 1L granulation vessel, with the transparent window completely immersed in 500cSt silicone oil. The horizontal distance between the center of the transparent window and the stirring paddle is 50~100mm. The industrial camera is connected to the data processing unit (industrial computer) via an RS485 communication line, which can transmit the collected data to the data processing unit (industrial computer) in real time. The data processing unit stores existing contour recognition programs and size distribution data statistics programs (e.g., an image processing system based on the InageJ 1.8.0 open source framework).

[0037] Step 2: Based on the acquired droplet images, extract the droplet contours, identify the droplets using existing contour recognition methods, determine the droplet size based on the obtained contours, and then obtain the droplet size distribution data of molten ADN under stirring based on the statistical results of the obtained droplet sizes. The droplet size distribution data includes Dv10, Dv50 and Dv90.

[0038] Step 3: Initially, the droplet diameter Dv50 = 230 μm, and Dv90 - Dv10 = 250 μm, which does not meet the cooling crystallization conditions. Therefore, the stirring rate is increased to increase the shear stress in the stirred flow field, leading to increased droplet breakage. Droplet images are continuously acquired during this process. When the stirring rate reaches 350 r / min (corresponding to...),... Figure 1 (1600s), the droplet Dv50 was detected to drop to 180μm, Dv90-Dv10=170μm, and then stirring continued at a stirring rate of 350r / min. During this process, images of the energetic material molten droplets were acquired at preset time intervals of 10s and the contour analysis described in step 2 was performed. After detection, the data obtained after stirring for 10 minutes met the cooling crystallization conditions and the dispersion was stable.

[0039] Step 4: Cool the product at a rate of 5℃ / min. When the temperature drops to 60℃, ADN begins to crystallize. During the crystallization process, an industrial camera is used to acquire particle images at an exposure time of 300μs and a frame rate of 300fps, with one frame of particle image acquired every 15 seconds, resulting in multiple images as shown below. Figure 3 Image of the crystallized particles shown;

[0040] Then, using existing image recognition methods, the particle diameter was statistically analyzed. The results showed that the crystalline particles had a Dv50 of 200 μm and a Dv90-Dv10 of 176 μm. The average size of the crystalline particles was small and the size distribution was relatively uniform. Under these conditions, the particle flowability was good, which met the process requirements, and the granulation test was completed.

[0041] In this embodiment, three batches of ADN melt crystallization experiments were conducted according to the above method. The results showed that the detection system operated continuously for 8 hours in a high-viscosity fluid environment without lens contamination, and the roundness measurement error remained stable within ±0.03. Finally, the average roundness of the ADN spherical particles was ≥0.92, and the particle size distribution Dv90-Dv10≤200μm. This indicates that the detection method can improve the quality stability of the granulation process by monitoring the product parameters online, and can maintain online monitoring for a long time without affecting the process. It solves the lag problem of traditional offline detection, shortens the detection response time to less than 30 seconds, and significantly improves the detection efficiency.

[0042] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0043] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for detecting particle shape and size during the melt suspension granulation process of energetic materials, characterized in that, Includes the following steps: Step 1: Add the dispersion medium and energetic material to the granulation vessel in sequence, heat to the melting temperature of the energetic material, and stir at the first stirring rate until the energetic material is melted and dispersed in the dispersion medium; During the melting and dispersion process of energetic materials, an industrial camera installed inside the granulation vessel is used to acquire images of the molten droplets of energetic materials at preset time intervals to obtain droplet images; Step 2: Determine the droplet size distribution data based on the acquired droplet images. The droplet size distribution data includes Dv10, Dv50, and Dv90. Step 3: Determine whether the droplet size distribution meets the cooling crystallization conditions, wherein the cooling crystallization conditions are: Dv50 < first threshold and Dv90-Dv10 < second threshold; If so, proceed to step 4; If not, increase the stirring rate and continue stirring until the droplet size distribution meets the cooling crystallization conditions, then proceed to step 4; Step 4: Cool the granulation vessel to the crystallization temperature of the energetic material to complete the crystallization of the energetic material. During the crystallization process, use an industrial camera inserted into the granulation vessel to collect images of the energetic material crystallized particles at preset time intervals. Step 5: Determine whether the diameter distribution of the crystallized particles meets the conditions for ending crystallization based on the collected images of energetic material crystallized particles. The crystallization granulation conditions include: Dv50 < first threshold and Dv90-Dv10 < second threshold. If yes, then end the granulation test; if no, reheat to the melting temperature of the energetic material and return to step 2.

2. The method for detecting particle shape and size in the melt suspension granulation process of energetic materials as described in claim 1, characterized in that, The solid-liquid ratio of the dispersion medium to the energetic material is 1% to 15%.

3. The method for detecting particle shape and size in the melt suspension granulation process of energetic materials as described in claim 1, characterized in that, The energetic materials include ammonium nitrate, dinitramide ammonium, and guanidine nitrate.

4. The method for detecting particle shape and size in the melt suspension granulation process of energetic materials as described in claim 1, characterized in that, The dispersion medium is selected from any one of silicone oil, liquid paraffin oil, toluene, cyclohexane, dodecane, hexadecane, styrene, and dioctyl sebacate.

5. The method for detecting particle shape and size in the melt suspension granulation process of energetic materials as described in claim 1, characterized in that, The first stirring rate mentioned in step 1 is 200 r / min to 400 r / min.

6. The method for detecting particle shape and size in the melt suspension granulation process of energetic materials as described in claim 1, characterized in that, The time interval mentioned in step 1 is 10 to 12 seconds.

7. The method for detecting particle shape and size in the melt suspension granulation process of energetic materials as described in claim 1, characterized in that, The first threshold mentioned in steps 3 and 5 is 400 μm, and the second threshold is 200 μm.

8. The method for detecting particle shape and size in the melt suspension granulation process of energetic materials as described in claim 1, characterized in that, The time interval mentioned in step 4 is 15~20s.

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