Preliminary evaluation of modifications to the FCB continuous evaporating crystallizers at Eston and Sezela

Five Fives Call Babcock (FCB) continuous evaporating crystallizers have bee n installed in South Africa. A first crystallizer of 64 m(3), with plate ca landria type, for C-sugar was installed in 1976 in the Maidstone sugar fact ory of the Tongaat-Hulett group. In the Illovo Group, a first CCTR (Cuite C ontinue with Tubes with Round body) evaporating crystallizer of 104 m(3) fo r C-sugar was installed in 1980 in the Gledhow sugar factory, and in 1981 t wo CCTR crystallizers of 90 m(3) each for B- and C-sugar were installed in the Illovo sugar factory (sugar factory transferred to Eston in 1995) and o ne CCTR crystallizer of 90 m(3) for C-sugar in the Sezela sugar factory. Th ese crystal liters were originally designed for the beet sugar industry, wh ere viscosity is much less than in the cane sugar industry. The initial per formance of the crystallizers, in terms of throughput and exhaustion, was p oor on low grade massecuites due to poor circulation. In 1995, the Eston crystallizer was installed in series with a Tongaat Hule tt Sugar (THS) vertical tube type continuous evaporating crystallizer and t he performance was evaluated. It was found that the capacity of the THS typ e crystallizer with an equivalent heating surface was twice that of the FCB crystallizer. Modifications were carried out on the FCB crystallizer to do uble its capacity and improved its performance. The Sezela crystallizer was modified in a similar man ner and then evaluated against the Australian Su gar Research Institute continuous evaporating crystallizer, on lower grade massecuites. This paper discusses the modifications and improved results ac hieved at both the Eston and Sezela sugar factories.