Mass-integration analysis: a technique for reducing methanol and effluent discharge in pulp mills

This work illustrates the use of mass integration methodology, a holistic approach to process design and operation. The method's utility derives from its ability to develop global insights about mass flow within a process. The design engineer can then use these insights to identify optimal strategies for allocating, routing, and separating process streams and targeted species. A case study is presented to illustrate the effectiveness of this approach in reducing methanol and wastewater discharges from a kraft pulp mill. The method targets all sources of a given pollutant simultaneously, allowing the engineer to evaluate opportunities for segregation, mixing, recycling, and interception of in-plant and terminal streams. Several visualization tools are described. These graphs are used to understand the global mass flow and to identify optimal allocation, interception, and recycle/reuse opportunities. Application : a case study illustrating the use of analytical tools that the design engineer can use to reduce waste and pollution from a kraft pulp mill.