Batch pan automation and its impact on energy conservation in cane sugar factories

In many sugar plants batch pans are still operated manually. The pan station is usually the largest vapour consumer of the plant and therefore its impact on the energy demand is high. Experience with pan automation system installations in Brazil, India and Pakistan has been gained in the last couple of years and results are presented. Pans operated manually usually require 2-5 t water per strike depending for example on pan size, feed brix and other parameters. The steam demand for this water addition is typically within a range of 2 to 16% exhaust steam on cane for the raw house pans and, if present, even larger for the refinery pans. The targets of modern pan automation systems are good crystal quality, capacity maximisation, smooth operation and low water/steam consumption. In general, it is possible to operate batch pans with no water addition at all. Apart from the control of single pans, it is also important to interlock the pans and optimise the speed in relation to the feed tank storage volumes, thus reducing vapour flow fluctuations in the plant. Modern pan automation systems allow a considerable reduction of the steam demand by eliminating, or at least reducing, the water additions. Another important aspect apart from the technical requirements is to overcome old operational habits that often cause drawbacks in practice.