DROP SIZE MODIFICATION IN BLACK LIQUOR SPRAYS FROM COMMERCIAL NOZZLESUSING PULSED FLOW

Improved operation of kraft recovery boilers is expected to result fro m knowing how to obtain a controlled, well-defined droplet size distri bution issuing from the black liquor spray nozzle. Black liquor drop s ize data were obtained from an environmentally acceptable spray facili ty capable of delivering liquor at normal firing temperatures using co mmercial nozzles. Image analysis techniques were developed from high-s peed video images which gave good two-dimensional representations of b lack liquor sprays. Previous work showed that black liquor sprays have a characteristic size distribution which is determined by the fluid m echanical forces breaking up the liquid sheet issuing from the nozzle. This work has centered on applying flow pulsation as an independently controlled force on the sheet breakup process in all attempt to chang e the drop size distribution. Experiments are described which feature controlled frequency flow pulsations. Results are presented which show the dependence of median drop size on pulsation frequencies up to 450 Hz.