Performance of the falling-film tube evaporator at Bingera Mill

For the 2018 season Bundaberg Sugar installed a 4,000 m 2 falling-film tube evaporator (FFTE) of the BMA design at No 1 evaporator position at Bingera Mill. This was the first installation of a FFTE into the Australian industry. An evaluation program was undertaken during the 2019 season to assess the performance with respect to heat-transfer efficiency, effect of scaling rates on heat transfer, de-entrainment efficiency of the juice droplets from the vapour outflow stream and the general operational performance. In addition, tracer studies were undertaken to determine the distribution of residence times for juice in the evaporator. Measurements were also undertaken to determine the extent of sucrose degradation occurring within the evaporator. Overall the evaporator has performed well with respect to the above test parameters. However, the effect of scaling on heat-transfer efficiency was only able to be evaluated for typically 120 hours of operation as the mill was restricted to five-day crushing operations each week due to the small drought-affected crop. A chemical clean of the evaporator was undertaken on shutdown each week. The results of the evaluation trials are presented and operational experiences during start-up, normal operation and shutdown phases are discussed. Key words Falling-film tube evaporator, heat-transfer coefficients, scaling rates, residence-time distributions