EFFECTS OF LOSS OF COOLING TOWER CAPACITY ON FACTORY OPERATIONS AT MACKNADE MILL

DURING the first week of the 2010 crush, Macknade Mill experienced a partial collapse of one cell of the factory’s cooling towers. A second cell was also compromised. It appeared that the factory would face a substantial problem resulting from hotter injection water and low vacuum, which would have greatest impact during the hotter months in the latter half of the season. Reductions in crushing rate resulting from low juice processing rates at the evaporators were the greatest concern. This paper describes the repair work undertaken at Macknade Mill to increase the cooling efficiency of the damaged tower and prevent further catastrophic failure. The paper also discusses the possible impact on factory performance from considerations of both throughput rate and sugar recovery. Some calculations were firstly undertaken to predict the effects of hotter injection water on the juice processing rate of the evaporators and hence the crushing rate. A second analysis was undertaken to predict the costs through reduced sugar recovery if maceration and filter wash water were reduced to allow higher crushing rates to be accommodated. The information presented in this paper was used in part as the financial justification for the replacement of the damaged cooling tower and sizing of the new tower. The actual effects of the reduction in the cooling tower’s capacity on the factory’s throughput and performance are discussed based on the data from the 2010 crushing season.