Hydrocyclones models

In each of these groups, the characteristic length is the cyclone diameter, D, and the characteristic velocity is V = AQ/tzD1. Various empirical hydrocyclone models indicate that the relationship between these groups is... 

Svarovsky L. A critical review of hydrocyclone models. In D Claxton, L Svarovsky, M Thew, eds. Hydrocyclyones 96. London Mech Eng Publi, 1996. 

Chen, W. 2002. Solid/liquid separation fundamentals and practice. AIChE Today Series. New York AIChE. Chen, W. 2004. The Use of Hydrocyclone Models in lYactical Design. 9th World Filtration Congress, New Orleans, LA, April 19-22. 

Chen W, Zydek N, Parma F. (2000) Evaluation of application of hydrocyclone models for practical applications. Chem. Eng. J., 80 295-303. 

Aplyng, A. C., Montaldo, D. and Young, P. A., Hydrocyclone models in an ore-grinding context , Int. Conf. Hydrocyclones (Cambridge, 1980), Paper 9, pp. 113-125, BHRA Fluid Engineering, Cranfield (1980)... 

Theoretical representation of the behaviour of a hydrocyclone requires adequate analysis of three distinct physical phenomenon taking place in these devices, viz. the understanding of fluid flow, its interactions with the dispersed solid phase and the quantification of shear induced attrition of crystals. Simplified analytical solutions to conservation of mass and momentum equations derived from the Navier-Stokes equation can be used to quantify fluid flow in the hydrocyclone. For dilute slurries, once bulk flow has been quantified in terms of spatial components of velocity, crystal motion can then be traced by balancing forces on the crystals themselves to map out their trajectories. The trajectories for different sizes can then be used to develop a separation efficiency curve, which quantifies performance of the vessel (Bloor and Ingham, 1987). In principle, population balances can be included for crystal attrition in the above description for developing a thorough mathematical model. 

Brayshaw, M.D., 1990. Numerical model for the inviscid flow of a fluid in a hydrocyclone to demonstrate the effects of changes in the vorticity function of the flow field on particle classification. International Journal of Mineral Processing, 29, 51. 

The flow patterns in the hydrocyclone are complex, and much development work has been necessary to determine the most effective geometry, as theoretical considerations alone will not allow the accurate prediction of the size cut which will be obtained. A mathematical model has been proposed by Rhodes et alP6), and predictions of streamlines from their work are shown in Figure 1.38. Salcudean and Gartshore137 have also carried out numerical simulations of the three-dimensional flow in a hydrocyclone and have used the results to predict cut sizes. Good agreement has been obtained with experimental measurements. 

Rhodes, N., Pericleous, K. A., and Drake, S. N. Solid Liquid Flow 1 (1989) 35. The prediction of hydrocyclone performance with a mathematical model. 

Du, B., Warsito, W., and Fan, L.-S. Ind. b Eng. Chem. Res. 44(14), 5020-5030 (2005). Dyakowski, T., and Williams, R. A., Hydrocyclone flow modeling—a continuous research challenge, Chapter 5, in "Innovation in Physical Separation Technologies Richard Mozley Symposium Volume, The Institution. Mining Metallurgy, London, pp. 61-73... 

In studies that involve the CFD analysis of turbulent fluid flow, the k-t model is most frequently used because it offers the best compromise between width of application and computational economy (Launder, 1991). Despite its widespread popularity the k-e model, if used to generate an isotropic turbulent viscosity, is inappropriate for simulation of turbulent swirling flows as encountered in process equipment such as cyclones and hydrocyclones (Hargreaves and Silvester, 1990) and more advanced turbulence models such as the ASM or the RSM should be considered. Because these models are computationally much more demanding and involve an increased number of empirical parameters compared to the k-e model, other strategies have been worked out (Boysan et al, 1982 Hargreaves and Silvester, 1990) to avoid the isotropic nature of the classical k-e model. 

Bubble columns Loop reactors Stirred tanks Hydrocyclones Reasonable Reasonable Reasonable Reasonable Modeling of chum-turbulent flow regime Modeling of chum-turbulent flow regime Improved geometrical representation of impeller and baffles Improved geometrical representation of system... 

There are numerous models to predict the separation efficiencies in hydrocyclones. One example is (Besendorfer 1996) ... 

EquHibrium orbit theory is a useful means of correlating and eiq>kiiimg the relation between flow rate and hydrocyclone cut size. Its use as a predictive tool is limited, however, as tests must be conducted to determine several parameters required in the model notably the flow split and the eiqionent on the radius in the cyclone. It does not provide any information on the pressure drop required to perform the separation, or on the arpness of the cut. 

The original residence time model [Reitema, 1961] was developed on the assumption that for 50% collection efficiency a particle must travel from the centre of the inlet pipe to the wall of the hydrocyclone, i.e. a distance of half of the inlet diamter, in the time that the particle is present within the hydrocyclone. The concept that only half of the uniformly suspended solids in the feed is processed giving the particle diameter at 50% collection efficiency was used in sigma analysis, see Section 8.2.2. 

There are numerous studies of hydrocyclone performance relating cut size, pressure drop and flow rate many involve the application of enq)irical constants in the theoretical models already discussed. The constants are strictly vahd only for the hydrocyclone geometry tested and operating conditions used, notably feed concentration. The situation is further complicated when the proposed equations are dimensionally inconsistent in the absence of empirical dimensioned constants. Some of the more well known equations are due to Bradley [1965], Holland-Batt [1982], Plitt Kawatra [1979], Reitema [1961] and Trawinsld [1969], These have been reviewed and compared in the book by Svarovsky [1984]. 

Gravity and centrifugal sedimentation can be combined for the same sample in order to directly determine Stokes diameter for a wide range of particle sizes. In such a way conversion are avoided and a mass distributions, applicable to processes where gravimetric efficiencies are relevant, can be properly derived. Ortega-Rivas and Svarovsky (1994) determined particle sizes distributions of fines powders using a combined Andreasen Pipette-pipette centrifuge method. They derive relations useful to model hydrocyclone separations, which were later employed to describe apple juice clarification. 

ABSTRACT Article has presented a numerical simulation method which was applied to analyzing Internal flow filed of the subsea gas-liquid hydrocyclone separator with Mixture model and RSM. The law of internal flow field distribution and separation characteristics of two-phase flow were obtained with the numerical simulation. Optimized separator structures were obtained with structure optimization design by simulation analysis. The numerical simulation can provide experiences for further study of subsea process equipment research and numerical simulation of hydrocyclones. 

SUBSEA GAS-OIL HYDROCYCLONE SEPARATOR MODEL 2.1 Subsea gas-oil hydrocyclone separator structure model... 

Subsea gas-liquid hydrocyclone separator grid model... 

Turbulence model of the subsea gas-liquid hydrocyclone separator... 

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