Exhaustion limits of Refinery molasses analysis: Prediction, boiling-down tests and impact on raw mill exhaustion

摘要

Previously unpublished work done in South Africa on the exhaustion of Refinery molasses is presented and discussed. The Target Purity Formula (derived by the South African Sugar industry for raw mills) is used as a measure to assess refinery exhaustion performance at Tongaat Hulett's Huletts Refinery over three decades. The results indicated that the approaches to target purity (Target Purity Differences) were firmly in the mid 20s. Boiling-down tests are presented, which demonstrate that refinery molasses has an equilibrium purity of approximately 10-12 units higher than the purities predicted by the Target Purity Formula for raw mill molasses. A modified version of the TP formula is proposed for refinery molasses. The true Target Purity Difference could therefore be argued to be in the region of 10-15 units. A brief (two-week) plant trial was carried out to determine the impact of blending a refinery molasses stream into a raw mill boiling house The non-pol and ash loading on the raw mill back-end was approximately 2.3 times than that would have arisen from an annexed refinery. No significant differences in exhaustion performance, due to the influence of the Refinery stream, were detected. One effect that was observed, however, was a slight elongation in the product sugar, but this did not translate into an impact on A-exhaustion