Black Liquor Evaporators - Operations

Multiple-effect evaporator sets are used to remove water from black liquor so that it can be fired into a recovery boiler and the pulping chemicals can be recovered for reuse. The efficient operation of the evaporators is critical to the mill's economic success and environmental compliance. This module describes the operations of the most common black liquor evaporator designs. It then details some common problems and their impact on the capacity and economy of this process.

•List hazards and safety guidelines for black liquor evaporator systems •Describe the operation of multiple effect evaporator sets •Define "steam economy," "multiple effect," "driving force," "boiling point rise," "scale," and "boil out" •Identify conditions that can cause low surface condenser vacuum •Identify conditions that can reduce evaporator set capacity •List methods to detect internal leaks in evaporators •List methods for locating condensate contamination sources