IMPROVED AIR PORT ARRANGEMENTS FOR THE SECONDARY AIR LEVEL

A variety of existing and improved secondary air designs for kraft rec overy furnaces were evaluated by physical and computational modelling techniques. Flow visualization, three-dimensional velocity mapping and laser methane tracer mixing tests were performed using a 1/8 scale is othermal flow model. Three-dimensional turbulent flow computational mo delling was done using a 200 000 node comprehensive simulation. The re sults of this modelling program indicate that current designs create a central flow core of high upward velocity with downflow regions aroun d the perimeter. Two of the proposed secondary air designs, interlaced jets and big/small opposed jets, produced gas flow patterns with impr oved mixing characteristics and significantly reduced central core pea k velocities and downflow regions.