Effects of flashing on spray characteristics of splashplate nozzles

The effects of flashing on black liquor spray patterns were investigated by analyzing numerous spray images obtained from laboratory experiments using small scale splashplate nozzles with water and experi-ments using actual size splashplate nozzles with black liquor. The results showed that flashing produces small drop-lets and increases droplet velocity. The liquor mass flow rate varies with direction: the rate is higher at the center than at the sides of the spray sheet, particularly at a lower excess temperature. At a higher excess temperature, how-ever, the mass distribution becomes more uniform across the spray sheet. Criteria were developed for predicting the onset of flashing and for estimating the mean droplet size of the black liquor spray under flashing conditions.This work was conducted as part of the research program on “Increasing energy and chemical recovery efficiency in the kraft process,” jointly supported by the Natural Sciences and Engineering Research Council of Canada and a consortium of the following companies: Andritz, Babcock & Wilcox, Boise, Carter Holt Harvey, Celulose Nipo-Brasileira, Clyde-Berge-mann, DMI Peace River Pulp, Fibria, International Paper, Ir-ving Pulp & Paper, Metso Power, MeadWestvaco, StoraEnso Research, and Tembec