NEW STIRRER FOR EVAPORATING CRYSTALLIZERS - LABORATORY DEVELOPMENT AND FACTORY TRIAL

Laboratory studies found that radially impelling stirrers in the high laminar flow zone, installed below the heating chamber, had better cir culating efficiencies than the present standard arrangement of a Kapla n propeller in the central tube of the heating chamber. The best resul ts were obtained with an impeller below a lead tube extension in the b ottom of the model apparatus. The Aarberg sugar factory and refinery p rovided an opportunity to test the laboratory results on an industrial scale and made it possible to measure in the same evaporating crystal lizer successively the heat transfer with the novel impeller turned ov er the mechanical power introduced with twice the circulating efficien cy of the Kaplan stiffer. At a 45% crystal content, both stiffer perfo rmed equally well.