Sweating of Paraffin Wax

Abstract

Equations of performance ror the bweating operation employed in the manufacture of paraffin wax are derived for the general case of arbitrary initial composition, expressing implicitly the compositions and melting points of the products as functions of the yield, assuming (1) that the components form ideal solid solutions; (2) that the quenched niclting points are mean values; and (3) that the melting poiiits of the individual components are linearly correlated with their respective relative crystallizabilities. For an idealized case, in which the charge is assumed to eontain a continuum of components uniforml? distributed with respect to relative crystallizability , the equations of performance assume a romparatively siniple form. .4 theoretical treatment of the effect of retention of liquid by the melting cake is also given.N THE manufacture of paraffin wax by the sweating process, two effects are sought: the removal of oil and the separation of waxes of different melting points. Both are accomplished by the same type of operation, which is usually applied repeatedly, with more or leas complicated schemes of recycling. At each sta,ge the wax is melted and allowed to solidify by slow cooling, then the east cake is slowly rewarmed, causing partial remelting. The oil and low inelt,ing wax run off as liquid a.nd the higher melting fraction remains behind as solid.No t,heoretical study of the sweating operation has been published and present practice is empirical. This paper presents a mathematical analysis of the opemtion along lines closely following those developed for some distillation problems in a preceding paper ( I ) . PRINCIPLES

A novel forced separation method for the preparation of paraffin with excellent phase changes

“…where C oil is the oil content of the feedstock, and C fÀoil is the oil content of the fraction. Eqn (15) shows that DP can be easily adjusted during vacuum sweating, and large DP values reect that high volumes of liquid ow out per unit time. In conventional sweating, P 1 ¼ P 2 , that is, DP ¼ 0.…”

“…The main methods used for paraffin production include molecular sieve dewaxing, 11 urea dewaxing, 12 molecular distillation, 13 the solvent method, 14 and sweating. 15,16 Molecular sieve dewaxing and urea dewaxing are unsuitable for the production of PCMs with high melting points. Distillation, which involves separating different hydrocarbon substances in accordance with their different boiling points, requires a high number of tower plates for precise separation with increased pressure drops.…”