Patent ID: 6235151
Filing Date: 2001-05-22
Classification: D21C

Abstract:
A method of inhibiting fouling of heat transfer surfaces in a multi-stage alkaline waste liquor evaporation plant in a chemical cellulose pulp mill having a bleaching plant which discharges a calcium containing effluent, comprising:(a) supplying a portion of the alkaline waste liquor from the evaporation plant to the bleaching effluent to increase the carbonate content of the effluent, and providing a combined effluent;(b) heating the combined effluent from (a) by direct contact with a heating medium;(c) maintaining the heated combined effluent from (b) for a period of time between about 1-20 minutes to reduce the amount of calcium in the effluent by precipitating calcium carbonate; and(d) evaporating the heat-treated combined effluent from (c) and alkaline waste liquor, in the evaporation plant, to inhibit fouling of heat transfer surfaces in the evaporation plant.