DIRECT CONTACT JUICE HEATING-WHEN TO USE AND WHEN NOT TO USE

DIRECT CONTACT JUICE heaters provide numerous advantages over non-contact juice heaters. However the condensation of vapour into the juice increases the process steam usage for juice evaporation and reduces the juice processing capacity of the evaporator set. Using lower pressure vapours than in the non-contact heaters helps to nullify these effects but suitable lower pressure vapours are not always available. Direct contact heaters should be utilised in those applications where the costs associated with increased process steam consumption or reductions in rate do not outweigh the benefits. The inherent costs resulting from increased process steam consumption are likely to be greater in those factories seeking very low process steam consumptions, e.g. lower than 35% steam on cane and, in those factories, direct contact heaters have fewer beneficial applications. The paper investigates the use of direct contact heaters for primary, secondary and clarified juice heating and also for heating condensate.