MODELLING THE EFFECT OF STEAM ECONOMY MEASURES ON EFFLUENT FLOWS FROM THE RAW SUGAR FACTORY

THIS PAPER REVISITS the topic introduced to this conference by Lavarack (2001) who reviewed the implications of reducing the process steam consumption on the water usage patterns in a cane sugar factory. It uses more complete models of the whole factory, including estimates of water losses in factory cooling systems, to investigate effluent losses from the factory and suggest improved relationships to improve predictions of effluent outflows. This paper presents insights into the effect of steam economy measures on the excess water which has to flow to effluent. This is done by linking a mass and energy model of the factory to a version of the 'Effluent Evaluation' spreadsheet referred to in the 1997 ASSCT Poster paper (Wright and de Viana, 1997). Modelling of the cane sugar factory is an excellent tool for investigating options for reducing the process steam consumption of the factory. The working of case studies with a linked model has enabled a simple relationship for the effluent water %cane to be derived from values such as the ‘water content of cane less the water lost in bagasse’ %cane, the total (LP pass-out plus cogeneration) steam %cane, the wet scrubber water loss %cane, and any added raw water %cane value. Consideration of these should lead to a better understanding of the water balance of the factory.