Pub Date : 2024-10-02DOI: 10.1016/j.powtec.2024.120335
Guangming Zhou, Le Xie
Various industrial applications are performed in liquid-solid fluidized beds where drag force plays a significant role in affecting the expansion characteristics of granular-bed, and then determines the mass/heat transfer performance. This study employs dimensionless learning data-driven modeling method, which is derived from the principle of dimensional invariance, to automatically discover the relationship between the drag coefficient and hydraulic dimensionless numbers from the liquid-solid fluidization data. It is found that the Fr number () also plays important role in improving the prediction accuracy of drag model except for Re number (). The proposed data-driven modeling method has desired robustness, and the yielded drag model can be applicable to other liquid-solid systems, such as water-polystyrene spheres and water-coal particles, although it is derived from the fluidization of spherical glass beads in rising tap-water. The proposed drag model can also provide good CFD simulation results that agree very well with the experiment data with the relative error less than 5 %.
在液固流化床的各种工业应用中，阻力对颗粒床的膨胀特性起着重要影响，进而决定传质/传热性能。本研究采用无量纲学习数据驱动建模方法，该方法源于量纲不变性原理，可从液固流化数据中自动发现阻力系数与水力无量纲数之间的关系。研究发现，除 Re 数（=dsulρl/μl）外，Fr 数（=ul2/gds）对提高阻力模型的预测精度也有重要作用。所提出的数据驱动建模方法具有理想的鲁棒性，所得到的阻力模型可适用于其他液固体系，如水-聚苯乙烯球体和水-煤颗粒，尽管它是由球形玻璃珠在上升的自来水中的流化推导出来的。所提出的阻力模型还能提供良好的 CFD 模拟结果，与实验数据非常吻合，相对误差小于 5%。
{"title":"A universal drag model for liquid-solid fluidization: Experiment, data-driven modeling, CFD modeling and simulation","authors":"Guangming Zhou, Le Xie","doi":"10.1016/j.powtec.2024.120335","DOIUrl":"10.1016/j.powtec.2024.120335","url":null,"abstract":"<div><div>Various industrial applications are performed in liquid-solid fluidized beds where drag force plays a significant role in affecting the expansion characteristics of granular-bed, and then determines the mass/heat transfer performance. This study employs dimensionless learning data-driven modeling method, which is derived from the principle of dimensional invariance, to automatically discover the relationship between the drag coefficient and hydraulic dimensionless numbers from the liquid-solid fluidization data. It is found that the <em>Fr</em> number (<span><math><mo>=</mo><msubsup><mi>u</mi><mi>l</mi><mn>2</mn></msubsup><mo>/</mo><mfenced><msub><mi>gd</mi><mi>s</mi></msub></mfenced></math></span>) also plays important role in improving the prediction accuracy of drag model except for <em>Re</em> number (<span><math><mo>=</mo><msub><mi>d</mi><mi>s</mi></msub><msub><mi>u</mi><mi>l</mi></msub><msub><mi>ρ</mi><mi>l</mi></msub><mo>/</mo><msub><mi>μ</mi><mi>l</mi></msub></math></span>). The proposed data-driven modeling method has desired robustness, and the yielded drag model can be applicable to other liquid-solid systems, such as water-polystyrene spheres and water-coal particles, although it is derived from the fluidization of spherical glass beads in rising tap-water. The proposed drag model can also provide good CFD simulation results that agree very well with the experiment data with the relative error less than 5 %.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120335"},"PeriodicalIF":4.5,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-02DOI: 10.1016/j.powtec.2024.120340
Guanwen Luo, Zhiwei Peng, Wanlong Fan, Ran Tian, Mingjun Rao, Guanghui Li
Microwave drying characteristics and kinetics of hematite pellets were investigated based on evaluation of the effects of initial mass, microwave power and pellet size during the drying process. The results showed the average drying rate increased with initial mass from 50 g to 80 g and microwave power from 600 W to 1000 W. However, it decreased with increasing pellet size from 10–12 mm to 14–16 mm. The process was successively controlled by external diffusion, internal diffusion, and chemical reaction. The Verma model was the most suitable kinetic model for describing the process. The effective diffusion coefficient of moisture ranged from 6.61 × 10−7 m2/s to 9.98 × 10−7 m2/s. The activation energy for the microwave drying process was only 2.83 W/g.
{"title":"Microwave drying characteristics and kinetics of hematite pellets","authors":"Guanwen Luo, Zhiwei Peng, Wanlong Fan, Ran Tian, Mingjun Rao, Guanghui Li","doi":"10.1016/j.powtec.2024.120340","DOIUrl":"10.1016/j.powtec.2024.120340","url":null,"abstract":"<div><div>Microwave drying characteristics and kinetics of hematite pellets were investigated based on evaluation of the effects of initial mass, microwave power and pellet size during the drying process. The results showed the average drying rate increased with initial mass from 50 g to 80 g and microwave power from 600 W to 1000 W. However, it decreased with increasing pellet size from 10–12 mm to 14–16 mm. The process was successively controlled by external diffusion, internal diffusion, and chemical reaction. The Verma model was the most suitable kinetic model for describing the process. The effective diffusion coefficient of moisture ranged from 6.61 × 10<sup>−7</sup> m<sup>2</sup>/s to 9.98 × 10<sup>−7</sup> m<sup>2</sup>/s. The activation energy for the microwave drying process was only 2.83 W/g.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"449 ","pages":"Article 120340"},"PeriodicalIF":4.5,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142526332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-02DOI: 10.1016/j.powtec.2024.120334
Ahmadreza Veiskarami, Maysam Saidi
This study was conducted with the aim of replacing different geometric fittings instead of the standard 90° elbow and trying to change the flow pattern to reduce erosion damage. Among fittings, the elbows are at a more serious risk. Numerical investigation of the present erosion with the novelty of research on non-spherical particles and changes in the impact angle of particles along with fluid flow using eight new proposed fittings, including two miter fittings, three blinded fittings, one reducer elbow fitting, and two spherical elbows fittings in comparison with the standard 90° elbow was controlled. The numerical simulation of the gas-solid two-phase flow of non-spherical particles was studied using the Euler-Lagrange approach. To carry out the study numerical, first, the gas flow was modeled by the Navier-Stokes equations and the turbulent Reynolds stress model, and then the solid particles were injected using Newton's equation. Finally, the erosion was calculated using Grant and Tabakoff model of the restitution of particles of after hitting the wall and the erosion model of Oka. The amount of erosion caused by changes in the flow pattern was investigated to evaluate the performance of the new proposed fittings. Numerical results for the most critical mode (Vin = 27 m/s and DP = 300 μm) showed that the new proposed fittings increase the erosion resistance by 22.5 % to 39.6 % compared to the standard 90° elbow. Also, in this research, the effect of different parameters including flow velocity, particle diameter size, particle input rate, and particle rotation on erosion were investigated.
{"title":"Numerical analysis of gas-solid flow erosion in different geometries as alternatives to a standard pipe elbow","authors":"Ahmadreza Veiskarami, Maysam Saidi","doi":"10.1016/j.powtec.2024.120334","DOIUrl":"10.1016/j.powtec.2024.120334","url":null,"abstract":"<div><div>This study was conducted with the aim of replacing different geometric fittings instead of the standard 90° elbow and trying to change the flow pattern to reduce erosion damage. Among fittings, the elbows are at a more serious risk. Numerical investigation of the present erosion with the novelty of research on non-spherical particles and changes in the impact angle of particles along with fluid flow using eight new proposed fittings, including two miter fittings, three blinded fittings, one reducer elbow fitting, and two spherical elbows fittings in comparison with the standard 90° elbow was controlled. The numerical simulation of the gas-solid two-phase flow of non-spherical particles was studied using the Euler-Lagrange approach. To carry out the study numerical, first, the gas flow was modeled by the Navier-Stokes equations and the turbulent Reynolds stress model, and then the solid particles were injected using Newton's equation. Finally, the erosion was calculated using Grant and Tabakoff model of the restitution of particles of after hitting the wall and the erosion model of Oka. The amount of erosion caused by changes in the flow pattern was investigated to evaluate the performance of the new proposed fittings. Numerical results for the most critical mode (V<sub>in</sub> = 27 m/s and D<sub>P</sub> = 300 μm) showed that the new proposed fittings increase the erosion resistance by 22.5 % to 39.6 % compared to the standard 90° elbow. Also, in this research, the effect of different parameters including flow velocity, particle diameter size, particle input rate, and particle rotation on erosion were investigated.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120334"},"PeriodicalIF":4.5,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-02DOI: 10.1016/j.powtec.2024.120341
Sujia Liu, Ga Zhang
Structuralized cementation has emerged as a promising method for reinforcing excavated slopes. The Discrete Element analysis is conducted on the structuralized cemented slopes under excavation with its validity verified through centrifuge model tests. The results indicate that structuralized cemented slopes exhibit progressive failure from the bottom to the top under excavation conditions. As the slope elevation decreases, the failure mode transitions from tension failure to shear failure, due to the presence of tensile stress only in the upper part of the slope. Microscopically, structuralized cementation prevents contact breakage, reducing fabric anisotropy and the variation of contact orientation from the vertical direction. Macroscopically, it increases the safety limit of slopes. The significant coupling between fabric evolution localization and local failure explains the failure mechanism of structuralized cemented slopes under excavation conditions. Increasing the size of the solidification zone reduces the localization extent of fabric evolution, thereby reinforcing the slope.
{"title":"DEM study of structuralized cemented slopes under excavation conditions","authors":"Sujia Liu, Ga Zhang","doi":"10.1016/j.powtec.2024.120341","DOIUrl":"10.1016/j.powtec.2024.120341","url":null,"abstract":"<div><div>Structuralized cementation has emerged as a promising method for reinforcing excavated slopes. The Discrete Element analysis is conducted on the structuralized cemented slopes under excavation with its validity verified through centrifuge model tests. The results indicate that structuralized cemented slopes exhibit progressive failure from the bottom to the top under excavation conditions. As the slope elevation decreases, the failure mode transitions from tension failure to shear failure, due to the presence of tensile stress only in the upper part of the slope. Microscopically, structuralized cementation prevents contact breakage, reducing fabric anisotropy and the variation of contact orientation from the vertical direction. Macroscopically, it increases the safety limit of slopes. The significant coupling between fabric evolution localization and local failure explains the failure mechanism of structuralized cemented slopes under excavation conditions. Increasing the size of the solidification zone reduces the localization extent of fabric evolution, thereby reinforcing the slope.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120341"},"PeriodicalIF":4.5,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-02DOI: 10.1016/j.powtec.2024.120330
Fumio Saito , Qiwu Zhang , Junya Kano
This article reviewed mechanochemical dechlorination of PVC by milling with additive from our basic research works on experiment and computer-chemistry. The dechlorination yield depends on additive and PVC characteristics as well as grinding conditions. In the dechlorination process, the chlorides and PVC residue have remained in the product, then they can be separated into solid and liquid phases by filtration after water leaching the products. Therefore, the valuable substance from either liquid or solid phases can be recovered by this operation. This leads to a feedstock recycling, and PVC is the source of chlorine for this chloride formation. In the first half of this article, the results on the mechanochemical dechlorination mechanism of PVC is mainly discussed, then, the last half of it dealt with the feedstock recycling using this kind of mechanochemical treatment with PVC for several scrap and wastes which contain valuable substances.
{"title":"Mechanochemical dechlorination of waste PVC resin and feedstock recycling","authors":"Fumio Saito , Qiwu Zhang , Junya Kano","doi":"10.1016/j.powtec.2024.120330","DOIUrl":"10.1016/j.powtec.2024.120330","url":null,"abstract":"<div><div>This article reviewed mechanochemical dechlorination of PVC by milling with additive from our basic research works on experiment and computer-chemistry. The dechlorination yield depends on additive and PVC characteristics as well as grinding conditions. In the dechlorination process, the chlorides and PVC residue have remained in the product, then they can be separated into solid and liquid phases by filtration after water leaching the products. Therefore, the valuable substance from either liquid or solid phases can be recovered by this operation. This leads to a feedstock recycling, and PVC is the source of chlorine for this chloride formation. In the first half of this article, the results on the mechanochemical dechlorination mechanism of PVC is mainly discussed, then, the last half of it dealt with the feedstock recycling using this kind of mechanochemical treatment with PVC for several scrap and wastes which contain valuable substances.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120330"},"PeriodicalIF":4.5,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.powtec.2024.120274
Maike Orth , Matthias Börner , Swantje Pietsch-Braune , Stefan Heinrich
Liquid injection is one of the, if not the most, critical steps in fluidized bed spray granulation as the product quality as well as the overall process stability can be massively influenced by the associated parameters. Therefore, this study aims to correlate spray parameters to the spray pattern and droplets produced from the nozzle and the resulting granule properties. First, the effect of spray variables on spray angle and droplet size and velocity was analyzed, revealing the spray air pressure as crucial parameter. Afterwards, spray agglomeration experiments were conducted according to a statistical experimental plan varying several process-related parameters in addition to the nozzle set-up. The product particle size distribution was shown to be impacted by a complex combination of the investigated variables with the liquid spray rate, spray and protection air pressure, and fluidization air flow as main influences.
{"title":"Influence of spray parameters on injected droplets and product properties in fluidized bed spray granulation","authors":"Maike Orth , Matthias Börner , Swantje Pietsch-Braune , Stefan Heinrich","doi":"10.1016/j.powtec.2024.120274","DOIUrl":"10.1016/j.powtec.2024.120274","url":null,"abstract":"<div><div>Liquid injection is one of the, if not the most, critical steps in fluidized bed spray granulation as the product quality as well as the overall process stability can be massively influenced by the associated parameters. Therefore, this study aims to correlate spray parameters to the spray pattern and droplets produced from the nozzle and the resulting granule properties. First, the effect of spray variables on spray angle and droplet size and velocity was analyzed, revealing the spray air pressure as crucial parameter. Afterwards, spray agglomeration experiments were conducted according to a statistical experimental plan varying several process-related parameters in addition to the nozzle set-up. The product particle size distribution was shown to be impacted by a complex combination of the investigated variables with the liquid spray rate, spray and protection air pressure, and fluidization air flow as main influences.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120274"},"PeriodicalIF":4.5,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.powtec.2024.120332
Suran Wang , Yao Lu , Yu Huang , Rafig Azzam
Knowledge of the shear behavior of landslide soil is very important for understanding landslide dynamics. This study investigated the shear behavior of base soil particle materials using ring shear tests with glass beads. Samples with varying particle sizes and distributions were examined to explore how particle size affects shear behavior at different shear velocities. Analysis of the samples included assessment of shear stress, displacement-shear stress fluctuations, and changes in the shear stress standard deviation. Results showed that with increasing shear displacement, shear stress fluctuations stabilize. Rather large difference particle size differences lead to more uniform particle mixing and a lower shear stress standard deviation. Conversely, when smaller particles predominate, particle mixing is less uniform, resulting in a higher shear stress standard deviation. Additionally, this study discussed the shear dilation and compaction mechanisms of samples under large displacement shear.
{"title":"Shear characteristics of nonuniform distribution of granular materials in ring shear test and impact on landslides","authors":"Suran Wang , Yao Lu , Yu Huang , Rafig Azzam","doi":"10.1016/j.powtec.2024.120332","DOIUrl":"10.1016/j.powtec.2024.120332","url":null,"abstract":"<div><div>Knowledge of the shear behavior of landslide soil is very important for understanding landslide dynamics. This study investigated the shear behavior of base soil particle materials using ring shear tests with glass beads. Samples with varying particle sizes and distributions were examined to explore how particle size affects shear behavior at different shear velocities. Analysis of the samples included assessment of shear stress, displacement-shear stress fluctuations, and changes in the shear stress standard deviation. Results showed that with increasing shear displacement, shear stress fluctuations stabilize. Rather large difference particle size differences lead to more uniform particle mixing and a lower shear stress standard deviation. Conversely, when smaller particles predominate, particle mixing is less uniform, resulting in a higher shear stress standard deviation. Additionally, this study discussed the shear dilation and compaction mechanisms of samples under large displacement shear.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120332"},"PeriodicalIF":4.5,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.powtec.2024.120339
Pengfei Liu , Xinran Zhu , Yuexin Han , Yanjun Li , Chuang Wen
As an abundant iron ore resource, limonite (mainly composed of goethite, hematite, lepidocrocite and other iron minerals) ore is seldom utilized due to its complex compositions, which has led to it lack mature processing methods. Magnetization roasting and magnetic separation is a promising method to process limonite ore. In this paper, the influence of microscopic pores on the reduction roasting of limonite ore was studied. X-ray diffraction, vibrating sample magnetometry, optical microscope, scanning electron microscopy, and the Brunauer-Emmett-Teller method of surface area analysis were used to study the dehydroxylation mechanism. The results indicated that goethite transformed into hematite, and the crystal structure of partly hematite probably changed when the dehydroxylation temperature increased from 600 °C to 1000 °C, making the sample more magnetic, the saturation magnetization increases significantly from 0.29 to 3.20 A·m2·kg−1. Simultaneously, SEM and BET showed the surface property has a big difference after roasting, more and more pores were generated with the temperature increased, then the specific surface area of the sample decreased from 75.94 to 0.59 m2·g−1. The reduction experiment results showed the dehydroxylation temperature has a significant effect on the reduction efficiency, the reduction time increased from 4 to 12.5 min with the temperature increased. This study has implications for the utilization of limonite ore using magnetization roasting technology.
{"title":"Micropores formation and effects in the magnetization roasting of limonite ore","authors":"Pengfei Liu , Xinran Zhu , Yuexin Han , Yanjun Li , Chuang Wen","doi":"10.1016/j.powtec.2024.120339","DOIUrl":"10.1016/j.powtec.2024.120339","url":null,"abstract":"<div><div>As an abundant iron ore resource, limonite (mainly composed of goethite, hematite, lepidocrocite and other iron minerals) ore is seldom utilized due to its complex compositions, which has led to it lack mature processing methods. Magnetization roasting and magnetic separation is a promising method to process limonite ore. In this paper, the influence of microscopic pores on the reduction roasting of limonite ore was studied. X-ray diffraction, vibrating sample magnetometry, optical microscope, scanning electron microscopy, and the Brunauer-Emmett-Teller method of surface area analysis were used to study the dehydroxylation mechanism. The results indicated that goethite transformed into hematite, and the crystal structure of partly hematite probably changed when the dehydroxylation temperature increased from 600 °C to 1000 °C, making the sample more magnetic, the saturation magnetization increases significantly from 0.29 to 3.20 A·m<sup>2</sup>·kg<sup>−1</sup>. Simultaneously, SEM and BET showed the surface property has a big difference after roasting, more and more pores were generated with the temperature increased, then the specific surface area of the sample decreased from 75.94 to 0.59 m<sup>2</sup>·g<sup>−1</sup>. The reduction experiment results showed the dehydroxylation temperature has a significant effect on the reduction efficiency, the reduction time increased from 4 to 12.5 min with the temperature increased. This study has implications for the utilization of limonite ore using magnetization roasting technology.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120339"},"PeriodicalIF":4.5,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.powtec.2024.120338
Kaizhong Zhang , Jiayang Li , Liang Wang , Shenguang Fu , Haoyu Zhang , Xiangqian Xing
Morphological microstructural evolution of tectonic coal determines CBM storage and transportation mechanism as well as the occurrence of coal and gas outburst. Scale-span morphological feature of original and tectonic coals was characterized by AFM, Raman spectrum and physisorption method. The results demonstrate that metamorphism could remold the surface property of coal from rugged band to flat porous structure with pore form factor from 0.572 to 0.831, promoting the formation of regular and round pores. Tectonism facilitates ability of gas sorption in coal, breaking the basic structural integrity. Metamorphism could facilitate the ordered macromolecular structural evolution on recombination and aromatization as well as condensation; besides, tectonism may promote the evolution and development of microcrystalline structure in advance. The aforementioned results have revealed essential differences in morphological microstructure between original and tectonic coals, which are of great guiding significance to safe mining of CBM and prediction of coal and gas outburst.
{"title":"Scale-span feature of surface analysis, macromolecular and pore structure in coal: Implications for inherent evolutionary mechanism of morphological microstructure","authors":"Kaizhong Zhang , Jiayang Li , Liang Wang , Shenguang Fu , Haoyu Zhang , Xiangqian Xing","doi":"10.1016/j.powtec.2024.120338","DOIUrl":"10.1016/j.powtec.2024.120338","url":null,"abstract":"<div><div>Morphological microstructural evolution of tectonic coal determines CBM storage and transportation mechanism as well as the occurrence of coal and gas outburst. Scale-span morphological feature of original and tectonic coals was characterized by AFM, Raman spectrum and physisorption method. The results demonstrate that metamorphism could remold the surface property of coal from rugged band to flat porous structure with pore form factor from 0.572 to 0.831, promoting the formation of regular and round pores. Tectonism facilitates ability of gas sorption in coal, breaking the basic structural integrity. Metamorphism could facilitate the ordered macromolecular structural evolution on recombination and aromatization as well as condensation; besides, tectonism may promote the evolution and development of microcrystalline structure in advance. The aforementioned results have revealed essential differences in morphological microstructure between original and tectonic coals, which are of great guiding significance to safe mining of CBM and prediction of coal and gas outburst.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120338"},"PeriodicalIF":4.5,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The chemical reaction between Ni and Al serves as a typical subject for the impact energy release of active metals. In fact, oxygen in the air will inevitably participate in the reaction process. This study systematically explores the various reaction mechanisms during the collision between Ni and Al nanoparticles in an oxygen environment through molecular dynamics simulations with reactive force fields. After elastic-plastic deformation, both Al and Ni nanoparticles can experience successive melting and micro-explosion triggered by exothermic reaction. Then, Al and Ni clusters are ejected into oxygen, resulting in a higher degree of oxidation reaction than intermetallic reaction. Moreover, the coupled development of intermetallic reaction and oxidation reaction is analyzed. Part of Al and Ni will form Al-O clusters and Ni-O clusters, respectively. The Al-Ni-O clusters are also observed via two pathways: (1) Al and Ni nanoparticles collide to induce intermetallic reactions forming Ni-Al compounds, followed by oxidation reactions; (2) Al-O clusters and Ni-O clusters react separately with Ni or Al. The oxidation clusters mainly exhibit approximately spherical and short-chain shapes with their size distribution conforming to the modified power-law distribution formula. Finally, the Al-Ni-O clusters are the low-coordination structure and account for about 70 % of the oxidation products in our simulation conditions. Enhancing velocity will cause the fragmentation of Al nanoparticles and accelerate the micro-explosion of Ni nanoparticles, consequently raising the reaction rate, and increasing the size of the nanoparticles raises the final number of Ni-Al intermetallic bonds, oxidative bonds, and the size of oxidation clusters. This study provides new insights into the potential reaction mechanisms of the active metal materials in the air environments.
镍和铝之间的化学反应是活性金属冲击能量释放的典型主题。事实上，空气中的氧气不可避免地会参与反应过程。本研究通过反应力场分子动力学模拟，系统地探讨了镍和铝纳米粒子在氧气环境中碰撞时的各种反应机制。在发生弹塑性形变后，铝纳米粒子和镍纳米粒子会在放热反应的触发下相继发生熔化和微爆炸。然后，铝和镍簇射向氧气，从而产生比金属间反应程度更高的氧化反应。此外，还分析了金属间反应和氧化反应的耦合发展。部分 Al 和 Ni 会分别形成 Al-O 簇和 Ni-O 簇。Al-Ni-O簇也是通过两种途径观察到的：（1）Al和Ni纳米粒子碰撞诱发金属间反应，形成Ni-Al化合物，然后发生氧化反应；（2）Al-O簇和Ni-O簇分别与Ni或Al发生反应。氧化簇主要呈现近似球形和短链形状，其尺寸分布符合修正的幂律分布公式。最后，Al-Ni-O 簇为低配位结构，在我们的模拟条件下约占氧化产物的 70%。提高速度会导致 Al 纳米粒子破碎，加速 Ni 纳米粒子的微爆炸，从而提高反应速率，而增大纳米粒子的尺寸则会提高 Ni-Al 金属间键、氧化键的最终数量和氧化簇的尺寸。这项研究为了解活性金属材料在空气环境中的潜在反应机制提供了新的视角。
{"title":"Atomistic insights into the reaction mechanism during the collision between Ni and Al nanoparticles in an oxygen environment","authors":"Kexin Zhu , Yifan Xie , Jian-Li Shao , Pengwan Chen","doi":"10.1016/j.powtec.2024.120321","DOIUrl":"10.1016/j.powtec.2024.120321","url":null,"abstract":"<div><div>The chemical reaction between Ni and Al serves as a typical subject for the impact energy release of active metals. In fact, oxygen in the air will inevitably participate in the reaction process. This study systematically explores the various reaction mechanisms during the collision between Ni and Al nanoparticles in an oxygen environment through molecular dynamics simulations with reactive force fields. After elastic-plastic deformation, both Al and Ni nanoparticles can experience successive melting and micro-explosion triggered by exothermic reaction. Then, Al and Ni clusters are ejected into oxygen, resulting in a higher degree of oxidation reaction than intermetallic reaction. Moreover, the coupled development of intermetallic reaction and oxidation reaction is analyzed. Part of Al and Ni will form Al-O clusters and Ni-O clusters, respectively. The Al-Ni-O clusters are also observed via two pathways: (1) Al and Ni nanoparticles collide to induce intermetallic reactions forming Ni-Al compounds, followed by oxidation reactions; (2) Al-O clusters and Ni-O clusters react separately with Ni or Al. The oxidation clusters mainly exhibit approximately spherical and short-chain shapes with their size distribution conforming to the modified power-law distribution formula. Finally, the Al-Ni-O clusters are the low-coordination structure and account for about 70 % of the oxidation products in our simulation conditions. Enhancing velocity will cause the fragmentation of Al nanoparticles and accelerate the micro-explosion of Ni nanoparticles, consequently raising the reaction rate, and increasing the size of the nanoparticles raises the final number of Ni-Al intermetallic bonds, oxidative bonds, and the size of oxidation clusters. This study provides new insights into the potential reaction mechanisms of the active metal materials in the air environments.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"448 ","pages":"Article 120321"},"PeriodicalIF":4.5,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号