Performance of the SRI radial design evaporator in the final-effect position at Victoria Mill

Victoria Mill installed a 4000 m² SRI-designed Robert evaporator in the final-effect position for the 2021 season. This evaporator is the first installation of this design in the final effect of the set. The design differs from the conventional Robert evaporators in the industry as it provides a radial flow of both vapour and juice and has a large central downtake for the outflow of juice/syrup. Previous installations of the design have been in the early evaporation stages, and these have provided improved separation of the inlet and outlet juice and increased heat-transfer efficiency. Evaluation trials demonstrated favourable heat-transfer performance, with the temperature difference across the evaporator being 3 to 4 °C lower than that typically required by the conventional Robert evaporators for the same heat-transfer rate. Modelling has shown that a conventional Robert evaporator would require one of the following changes to maintain the same crushing rate: (1) a 7% increase in installed heating surface area for the set; (2) an increase in exhaust pressure of 13 to 15 kPa and an increase in the process steam on cane by 0.6%; or (3) a reduction in added water to the milling train and the mud filters of 19%. Increased sugar losses in bagasse and mud cake would reduce sugar yield from the cane supply for the factory. The test program has determined that minor modifications to the juice outlet arrangements should be incorporated in future installations of the design.