1、1、英文原文Prediction of the performance of dense medium cyclones in coal preparationJ. Chen a, K.W. Chu a, R.P. Zou a, A.B. Yu a,*, A. Vince ba Laboratory for Simulation and Modelling of Particulate Systems, School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052
2、, Australia b Elsa Consulting Group Pty. Ltd., PO Box 8100, Mt. Pleasant, QL 4740, Australiaa b s t r a c tThe Dense medium cyclone (DMC) is a high-tonnage device that is widely used to up grade run-of-minecoal in coal industry. Its complicated multiphase flow structure is difficult to investigate e
3、xperimentally.In recent years, Computational Fluid Dynamics (CFD) and in particular, its combination with Discrete Element Method (DEM) have been shown to be effective in overcoming this difficulty. However, such amathematical model, particularly the CFD-DEM one, is very time-consuming in computatio
4、n and notsuitable for engineering application. In this paper, based on the CFD and CFD-DEM simulated data, a PC-based mathematical model is formulated to predict the performance of DMCs under various conditions.It first discusses how such a model can be developed, with its validity examined against
5、the collected plant data. Then, the effects of some key variables related to DMC geometry, operational conditions and materials properties are examined. It is shown that the proposed model can indeed offera convenient way to quantify the effects of different variables, being useful in the design and
6、 control ofDMCs under different conditions._ 2011 Elsevier Ltd. All rights reserved.1. IntroductionDense medium cyclones (DMCs), also known as heavy mediumcyclones, are versatile separators known to be efficient, high tonnage devices suitable for upgrading particles in the 500.5 mm size range. Their
7、 working principle has been well documented (for example, see (King and Juckes, 1984; Svarovsky,1984; Wills, 1992). DMCs have been widely used as separatorsin most of the modern coal plants and in a variety of mineral plantstreating iron ore, magnetite, dolomite, diamonds, and leadzincores. Especial
8、ly, they have been proved to be effective in the coalindustry, and are used in processing the vast majority of tonnesfed to Australian coal preparation plants.The flow in a DMC is very complicated because of the presenceof swirling turbulence, air core and segregation, and involves multiphases: gas,
9、 liquid, solid and medium particles of different sizes.Some efforts have been made to experimentally study the flow ina dense medium cyclone, but such an experimental method istechnically difficult and expensive. These situations force the designers and researchers to rely on empirical equations for
10、 predictingthe performance of DMCs (Davis, 1987; Wood, 1990). However,constrained by the research techniques and conditions,previous empirical work has to be limited to phenomeno logical descriptions that rarely touch upon the underlying physics (e.g.the particleparticle, particlefluid and particlew
11、all interactions).This would not result in much improved understanding of the fund amentalsof cyclones under different conditions. In fact, the limit ationsinherent in the empirical nature of the model have beenrecognized. For example, it is known that such an empirical equationcan only be used with
12、in the extremes of the experimental datafrom which the model parameters were determined. In particular,caution should be taken in its utilization for performance predictionunder different conditions, or combinations of various conditions,outside those encountered in the data base from which itwas de
13、veloped. Therefore, it is desirable, and certainly more reliable,to develop a mathematical description of the fundamentalswhich govern the multiphase flow and predict the performanceof DMC under different production conditions. The flow in a DMC is very complicated because of the presenceof swirling
14、 turbulence, air core and segregation, and involves multiphases: gas, liquid, solid and medium particles of different sizes.Some efforts have been made to experimentally study the flow ina dense medium cyclone, but such an experimental method istechnically difficult and expensive. These situations f
15、orce thedesigners and researchers to rely on empirical equations for predictingthe performance of DMCs (Davis, 1987; Wood, 1990). However,constrained by the research techniques and conditions,previous empirical work has to be limited to phenomenologicaldescriptions that rarely touch upon the underly
16、ing physics (e.g.the particleparticle, particlefluid and particlewall interactions).This would not result in much improved understanding of the fundamentalsof cyclones under different conditions. In fact, the limit ationsinherent in the empirical nature of the model have beenrecognized. For example, it is known that such an empirical equationcan only be used within the extremes of the experimental datafrom which the model parameters were determined. In particula
