Heat transfer and scaling phenomena in black liquor evaporatio

Scaling of the black liquor onto a heat transfer surface was studied at different heat fluxes and concentrations in both batch and continuous systems. Temperature gradients and thus heat transfer coefficients were monitored versus time as the scaling occurred. Scaling rates were identified from the deposits collected at the end of each experiment.;It has already been reported widely in the literature that the major scaling components in the black liquor are $rm Nasb2SOsb4$ and $rm Nasb2COsb3,$ which precipitate in the form of burkeite. They are known to precipitate when they reach their solubility limit, which is above 50% black liquor total solids concentration. Their precipitation from the bulk solution of 1:1 $rm Nasb2SOsb4$ and $rm Nasb2COsb3$ was studied mostly at 20% concentration and their contribution to the black liquor scaling was investigated.;Compositions of the deposits analysed by different techniques confirmed that they contain $rm Nasb2SOsb4$ and $rm Nasb2COsb3.$.;In this study investigation of the electrostatic field technology on the reduction of black liquor scaling rate was also carried out.