Scrubber liquid recovery in biomass gasification plants: centrifugation as a method for tar separation

Many gasification plants use scrubber systems for the removal of tars from producer gas. The cost of the scrubber liquid represents a considerable part of the operating cost, which could be decreased by regenerating the spent scrubber liquid by separating it from ash residues and heavy tars. In this study, different types of spent scrubber liquids were regenerated using a centrifuge. The effect of centrifugation time (1.5–10 min) and sample temperature (50–90 °C) on the separation efficiency was studied. Based on the results, the separation of tars from the scrubber liquids can be ranked as follows: diesel > RME > linoleic acid > linseed oil > rapeseed oil > motor oil. This ranking correlates to the viscosity of the different scrubber liquids, with the separation efficiency increasing with decreasing scrubber liquid viscosity. The best separation efficiency was achieved for scrubber liquids with low viscosity at 90 °C and 10 min of centrifugation time. The results obtained indicate that centrifugation can be used for the regeneration of spent scrubber liquid.