Dynamic optimization of batch centrifugal separation by purging monitoring.
Correct timing of the steps in a batch centrifugal cycle is important to get the best separation of crystals and mother liquor. Too early application of wash water will mix the wash water with the mother liquor, reducing the washing efficiency of the water. Too late application of the wash water will cause the film of mother liquor on the crystals to be dried out by air pressed through the crystal wall by the high G-factor. Too early or too late shift between low and high purity run-off will send too much non-sucrose back in the process or too much sucrose to molasses. Too early stop of spinning will leave too much humidity with the crystals, requiring more energy for drying. Too late stop of spinning will make it difficult to discharge the crystals. For factories with constant massecuite quality and constant mixer filling the centrifugal cycle can be determined once and be valid forever. For all other factories, static settings for the centrifugal cycle will lead to less perfect separation. Results from purging sensors applied on various massecuites are presented showing different purging patterns.