Abstract
This paper has for its object an exposition and discussion of new facts brought out in consequential tests and studies of the design and operation of vacuum pans in the sugar industry, and the logical consequence of these data in the readoption of the rather old and generally discarded principle of mechanical circulation.
It is demonstrated by actual observations that the heating of the heavy and viscous masse-cuite circulating through the tubes of the pans is not at all uniform, as has generally been assumed. During critical periods of operation, streamline flow obtains and the liquid is heated only at the skin. Recorded differences of temperature in the masse-cuite show observable variations of fully 30 F, with all indications of unobservable differences of as much as 50 F. With mechanical circulation, as proposed by the author, these variations are cut down to about one-fourth of their intensity.
This radically different operation makes possible new and interesting results, among which may be mentioned uninterrupted growth of sugar crystals, uniformity of products, greatly decreased formation of conglomerates, absence of false grain, faster operation, lower-steam pressures.
One of the very interesting developments also brought out in the paper is a method of cooling low-grade strikes in the pans themselves in the short period of four hours, thus eliminating the time-honored crystallizer from the raw-sugar industry.
