Low-Purity Beet Sugar Factory Materials

Abstract

INTHE manufacture of beet sugar, the extracted, defecated, and concentrated beet juices are normally subjected to three vacuum pan crystallizations. The third crystallization is carried out with difficulty, the rates of crystallization being greatly retarded as a result of the high concentration of nonsugars. These rates are so low that it is not practical to carry crystallization to completion in the vacuum pans. After pan boiling, common practice is to cool the fillmass (mass of crystals and mother liquor) in waterjacketed crystallizers. Crystallization for several days is frequently involved in the usual type of crystallizer, and the use of crystallizers employing more rapid cooling has become common in recent years. Most of them have cooling surfaces inside, and are typified by the Blanchard, Lafeuille, and Werkspoor apparatus. Two Werkspoor crystallizers are used at the Woodland factory. The Woodland factory includes a Steffen unit.In the newer types the rate of fillmass cooling is capable of control, and data on effective rates of crystallization in crystallizer fillmass are desirable to determine optimum timetemperature curves.Considerable work has been published on rates of crystallization of sucrose, but the great bulk has dealt with solutions of pure sucrose.

Nucleation in Sucrose Solutions

“…Although these figures are approximate only, in the sense that they merely represent conditions under which crystallization becomes visibly appreciable under ordinary operating and experimental conditions, they form a very practical working guide for the sugar boiler (8,14). The division points are elevated considerably if precautions are taken to exclude foreign or heterogeneous nucleation (IS, 2S), and if the purity of the sirup is decreased (4, 28).…”

Kinetics of Sucrose Crystallization

“…An abundance of information concerning the crystallization behavior of sucrose from natural sirups is available in the literature (12,15,17,18,20,23), but very little is suitable for a direct quantitative test of Equation 2. None such was found for cane massecuites, but for beet fillmasses the very complete data of Nees (18) and coworkers (9), McGinnis (15), and Nakhamovich and Zelikman (17) are available.…”

“…The first and last of these -were computed to units more appropriate to the present purpose, using the determined solubility data in the former case and (arbitrarily) Grut's (7) tables in the latter. McGinnis, Moore, and Alston's data (15) for a green sirup do not cover as extended an impurity concentration range and therefore are not reported here.…”