Use of a purge sensor to improve performance and reduce supervision of batch centrifugals

Batch centrifugals are used widely to separate the product sugar crystals from the mother molasses. Currently the fugal station operator relies on visual inspection and sounds to judge the optimum time and centrifugal speed when to apply the wash water. There are no transducers to advise when the wash water should be applied in the cycle to produce the sugar at the required quality specification but at the same time minimise the addition of wash water. By minimising the water addition, less sugar is dissolved and so less sugar must be recrystallised on the pan stage, thus reducing the loading on the pan stage and centrifugal stage. Approximately 2.8 kg sugar is dissolved for each kg of water added.

As the purging qualities of massecuites vary from strike to strike and the performance characteristics of individual centrifugals differ, the challenge for the operator is to set the process parameters to keep each machine operating efficiently.

This project assesses a purge sensor (supplied by Neltec Denmark) which measures the impact of the molasses and water leaving the centrifugal basket and hitting the monitor casing. The trials were undertaken on a batch centrifugal at Millaquin Mill. The investigations have determined the preferred manner by which operators would use the sensor to best effect and provide an important step to tighter management of the centrifugal station and increased automation.