Jiongjie He , Jingxuan Yang , Guo Xu , Xiaoqing Fu , Xiaogang Hao
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引用次数: 0
Abstract
The maximum efficiency inlet velocity (MEIV) serves as the upper limit for the inlet velocity that defines the separation efficiency in cyclone design and operation. In this paper, a combination of numerical and experimental methods is used to study MEIV. Experimental findings indicate that the MEIV is 22 m/s for a median particle size of 12.39 μm (coarse powder) and 35 m/s for a median particle size of 2.93 μm (fine powder). Meanwhile, the amount of escaped fine powder is reduced by 25% compared to that at an inlet velocity of 22 m/s. Computational fluid dynamics (CFD) simulations have shown that the inconsistency between tangential and axial velocity growth of inlet velocity with respect to various powder diameters can explain this phenomenon. As the inlet velocity increases, the peak axial velocity exhibits a stepwise increase. When the peak value remains constant, the peak width increases. This phenomenon is called stagnation of the axial velocity. During the axial velocity stagnation step, the residence time of back-mixed particles vary. In contrast, the tangential velocity increases linearly with the inlet velocity, resulting in an enhanced secondary separation of the inner vortex. Both factors hinder the escape of fine particles due to entrainment by a rapid upward airflow. The inlet velocity range corresponding to the stagnation step of the fine powder is larger than that of the coarse powder. Therefore, the MEIV of the fine powder is higher.
期刊介绍:
Powder Technology is an International Journal on the Science and Technology of Wet and Dry Particulate Systems. Powder Technology publishes papers on all aspects of the formation of particles and their characterisation and on the study of systems containing particulate solids. No limitation is imposed on the size of the particles, which may range from nanometre scale, as in pigments or aerosols, to that of mined or quarried materials. The following list of topics is not intended to be comprehensive, but rather to indicate typical subjects which fall within the scope of the journal's interests:
Formation and synthesis of particles by precipitation and other methods.
Modification of particles by agglomeration, coating, comminution and attrition.
Characterisation of the size, shape, surface area, pore structure and strength of particles and agglomerates (including the origins and effects of inter particle forces).
Packing, failure, flow and permeability of assemblies of particles.
Particle-particle interactions and suspension rheology.
Handling and processing operations such as slurry flow, fluidization, pneumatic conveying.
Interactions between particles and their environment, including delivery of particulate products to the body.
Applications of particle technology in production of pharmaceuticals, chemicals, foods, pigments, structural, and functional materials and in environmental and energy related matters.
For materials-oriented contributions we are looking for articles revealing the effect of particle/powder characteristics (size, morphology and composition, in that order) on material performance or functionality and, ideally, comparison to any industrial standard.