Cake and precoat filtration – Evaluating influences of increased backwash efficiency on cloth lifetime

Abstract

In beet juice purification the greatest challenge is to evade a frequent blockage of the filter cloth during carbonation slurry filtration. Lenzing Filtration started an investigation on backwash efficiency of tubular pressure candle filters and how this affects the lifetime of filter cloth in carbonation slurry filtration. The patent pending CakeFil filter candle of Lenzing Filtration is made from a continuous casted structure, closed at the lower end with an on-welded plug and at the upper end with a connector to the filtrate chamber. After 85 backwashes under laboratory conditions the CakeFil technology had approx. 77% less residues compared to two different standard candle filters. Pilot-scale testing in a German sugar factory with carbonation slurry 1 confirmed the outstanding lab performance as the filter cloth of LENZING CakeFil endured the entire campaign of 71 days without any filter cloth change, whereas the standard candle filter clothes had to be changed four times and external washing had to be performed three times during the same period. Also the filtrate-quality analysis showed that the results were identical compared to existing candle filters quality.