Using process integration to approach the minimum impact pulp mill

A low level of energy use is an important feature of the minimum impact mill. Process integration is used in the pulp and paper industry and other industries to reduce the use of fuels and cooling water. As the industry is in a state of rapid change, a methodical approach to process integration is useful. Pinch analysis is well established as such a tool. In the present paper, composite curves are used to analyze possibilities for process integration in combination with changes in process design. Several examples, including improved integration of the digester and analyses of the whole mill, show that this is an approach that gives good guidance early in the design process. Substantial utility savings can be identified; these are on the order of 2-4 GJ per tonne of pulp compared with already energy-efficient mills