The Effect of Added Water Temperature on Milling Train Operation and Performance

Abstract

Four recent factory experiments have been conducted to provide information to determine an optimal added water temperature. The results were not completely conclusive but did provide some further insight into the effect of added water temperature. The effect of added water temperature on extraction has proven particularly difficult to measure. There is little doubt that bagasse is more compressible at higher temperature. Two experiments have shown that bagasse moisture content is lower at higher temperature. These effects are most likely related. Two experiments produced indirect evidence of an increase in extraction with higher added water temperature. With bagasse being more compressible, mill capacity is increased at higher temperature. The use of a heat exchanger to cool added water with mixed juice reduces heat loss and consequently reduces steam usage for primary heating of juice. Some of the lost heat may serve a useful purpose in increasing boiler efficiency, resulting in more efficient use of bagasse. Hotter added water does not appear to be a complete solution for mill hygiene since even the hottest added water investigated only provides sufficient benefit for the last one or two mills. There remains considerably more work to identify the optimal added water temperature. The main outstanding issues are the effect of added water temperature on extraction, the effect of hotter bagasse on boiler efficiency through moisture content or temperature and the impact of bagasse temperature on hygiene.