Particulate, processing

A. D. Randolph and M. A. Larson, Theoy of Particulate Processes, Academic Press, Inc., New York, 1971. 

Further details can be found in several texts including those on the theory of particulate processes (Randolph and Larson, 1988), crystallization (Van Hook, 1961 Bamforth, 1965 Nyvlt, 1970 Jancic and Grootscholten, 1984 Garside etal., 1991 Nyvlt, 1992 Tavare, 1995 Mersmann, 2001 Myerson, 2001 Mullin, 2001) and precipitation (Walton, 1967 Sohnel and Garside, 1992). 

Filters generally achieve a lower final moisture content than obtained by gravity sedimentation and are often fed from thickeners, as indicated in the schematic particulate process shown in Figure 9.2. In this chapter the principles of slurry filtration will be described and certain simplified filter design equations derived. For more complex derivations the reader is referred to specialist texts e.g. Coulson and Richardson (1991), Wakeman (1990a) and Purchas (1981). 

As mentioned above, the unit operation of crystallization rarely exists in isolation but is normally part of a wider particulate processing system as illustrated schematically, in a very simplified form, in Figure 9.2. A particular feature of such processes is the variety of unit operations and the range of equipment types that may be employed at any stage. 

Since crystallization is a particulate process, the model representing size distribution is written in terms of functions. Evans (1989) and Hounslow and... 

Hounslow, M.J. and Wynn, E.J.W., 1992. Modelling particulate processes Full solutions and short-cut. Computers and Chemical Engineering, 16, S411-S420. 

Randolph, A.D. and Larson, M.A., 1988. Theory of Particulate Processes, 2nd edition. New York Academic Press. 

Most process engineering problems involve mass and energy balances. However, in particulate processes, especially in cases where particle number rather than mass is of primary importance, a balance over the population of materials of a given size in the system is often necessary. This is particularly... 

Randolph, A. D. Larson, M. A. "Theory of Particulate Processes Academic Press New York, 1971. 

A. D. Randolph and M.A. Larson Theory of Particulate Processes" 2nd Edition Academic Press (San Diego, CA, 1988). 

Method of Lines. The method of lines is used to solve partial differential equations (12) and was already used by Cooper (I3.) and Tsuruoka (l4) in the derivation of state space models for the dynamics of particulate processes. In the method, the size-axis is discretized and the partial differential a[G(L,t)n(L,t)]/3L is approximated by a finite difference. Several choices are possible for the accuracy of the finite difference. The method will be demonstrated for a fourth-order central difference and an equidistant grid. For non-equidistant grids, the Lagrange interpolation formulaes as described in (15 ) are to be used. 

J. Lister, Forward to special edition of powder technology from Control of Particulate Processes VI , Powder Technol. 124 (2002) 175. 

Fig. 3.2. Formal representation of mechanisms of size change in particulate processes [6].

A D Randolph, M A Larson, AIChE J 1962, 8, 639, the concepts are described in more detail in A D Randolph, M A Larson, Theory of Particulate Processes, 2nd ed, Academic Press, San Diego, 1988... 

Randolph and Larson—Theory of Particulate Processes, Academic Press. 

The population balance is used as a method of accounting for particles as they go throng a process, such as grinding, dassiiication, crystallization, a [regation, or grain growth. This chapter is devoted to the development of population balances, because it is of fundamental importance to several other of the diapters in this book. The chapter draws heavily on the excellent text Theory of Particulate Processes by Randolph and Larson [1]. The number density of particles N(L) (with units of number of particles per unit volume) is equal to the integral of the population 7)q(L) from size L to L + AL and is defined as... 

This is the macroscopic population balance, which is a more useful form of population balance for describing transient and steady state particle size distributions in well-mixed vessels. This population balance in conjunction with mass and energy balances gives a complete description of particulate processes in well-mixed vessels. 

Significant changes in the moisture content in the drum due to recycle fluctuations (recwcle of dry granules in fertilizer granulation) [Zhang et al.. Control of Particulate Processes IV (1995)]. 

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