Assessing the suitability of operating high-grade batch pans in Australian factories on low-pressure vapour

For Australian sugar factories to achieve substantial reductions in process steam consumption will require that the pan stages use bleed vapour from the evaporators, and preferably vapour 2 or vapour 3. However, most Australian pan stages comprise large, unstirred batch pans for the high-grade boiling duties, which make it difficult to use lower pressure vapour than the currently used exhaust steam or vapour 1, without experiencing a reduction in productivity of the pan stage. A recent study of the heat-transfer performance of several pans in the Australian industry provides heat-transfer performance data and correlations for the run-up and heavy-up operations. This investigation applies those correlations to determine the suitability of using vapour 2 or vapour 3 for the run-up of the high-grade batch pans. More recently installed batch pans in the industry are able to run-up to pan full using vapour 2, but using vapour 3 is not feasible. Several recommendations are made to allow the batch pans to operate more effectively on low-pressure vapour.