REDUCTION OF HEAT-TRANSFER FOULING BY THE ADDITION OF WOOD PULP FIBERS

Heat transfer experiments with a saturated CaSO4 solution were carried out in a closed-loop test rig containing an externally heated test se ction. Reproducible fouling curves were measured for the solution with out fibers. The buildup of deposit was asymptotic, which implied that the fouling process was a combination of crystallization and particula te fouling. The addition of a small quantity (less than 0.05 mass perc ent) of softwood chemical pulp fiber to the bulk reduced the rare of f ouling significantly. At 0.05 mass percent fiber-addition, no fouling was measured in the rest rig during 7 days of continuous running. The addition of fibers reduced the rare of deposit buildup and potentially offers a new method of fouling mitigation. Only a low concentration o f fibers is needed, and the nontoxic fibers are easily removed.