Multicomponent separations

The number of columns ia a multicomponent train can be reduced from the N — 1 relationship if side-stream draw-offs are used for some of the component cuts. The feasibiUty of multicomponent separation by such draw-offs depends on side-stream purity requirements, feed compositions, and equihbrium relationships. In most cases, side-stream draw-off distillations are economically feasible only if component specifications for the side-stream are not tight. If a single component is to be recovered ia an essentially pure state from a mixture containing both lower and higher boiling components, a... 

Chromatography Chromatography is a sorptive separation technique that allows multicomponent separations in both gas and Hquid phase. As a preparative tool, it is often used as a displacement-purge process, although many applications employ an inert-displacement mode, especially for use in analysis. General characteristics and operating modes are discussed in a separate part of this section. 

A very low gas rate in a column several feet tall with internal reflux can sometimes be used to effect difficult multicomponent separations in batch operation [Lemlich, Principles of Foam Fractionation, in Periy (ed.). Progress in Separation and Purification, vol. 1, Inter-science, New York, 1968, chap. 1]. 

The program is rather slow in execution and therefore the model is limited to an eight-plate column, which is rather unrealistic for this multicomponent separation. The program is therefore given only for example purposes and a real simulation should involve rather more plates. As in BSTILL, the speed of calculation is also very sensitive to the magnitude of the liquid holdup on the plates, which again are large compared to normal practice. 

Smith and Brinkley developed a method for determining the distribution of components in multicomponent separation processes. Their method is based on the solution of the finite-difference equations that can be written for multistage separation processes, and can be used for extraction and absorption processes, as well as distillation. Only the equations for distillation will be given here. The derivation of the equations is given by Smith and Brinkley (1960) and Smith (1963). For any component i (suffix i omitted in the equation for clarity)... 

Several different approaches have been taken to develop programs that are efficient in the use of computer time, and suitable for the full range of multicomponent separation processes that are used in the process industries. A design group will use those methods that are best suited to the processes that it normally handles. 

Marchetti, N., Felinger, A., Pasti, L., Pitrogrande, M.C., Dondi, F. (2004). Decoding two-dimensional complex multicomponent separations by autocovariance function. Anal. Chem. 76, 3055-3068. 

FUNDAMENTALS THE STATISTICAL DESCRIPTION OF COMPLEX MULTICOMPONENT SEPARATIONS... 

DECODING ID AND 2D MULTICOMPONENT SEPARATIONS BY USING THE SMO POISSON STATISTICS... 

Chromatography Chromatography is a sorptive separation technique that allows multicomponent separations in both gas and liquid... 

B.G. Rong and A. Kraslawski. Optimal design of distillation flowsheets with a lower number of thermal couplings for multicomponent separations. Ind. Eng. Chem. Res., 41 5716-5726, 2002. 

Sivasubramanian, M. S. and Boston, J. F., 1990, The heat and mass transfer rate-based approach for modelling multicomponent separation processes, in Computer Applications in Chemical Engineering, pp. 331-336. Elsevier, Amsterdam. 

---