Opportunities for Process Integrated Evaporation in a Eucalyptus Pulp Mill and Comparison with a Softwood Mill Study
Paper in proceedings, 2007

Significant energy savings can be made in the pulp and paper industry by implementing process-integrated evaporation (PIvap). The concept of PIvap has been evaluated for a Eucalyptus mill producing bleached kraft market pulp in Portugal and the results were compared to the ones from an earlier model mill study of a soft wood mill. In the eucalyptus mill there were, theoretically, 0.86 GJ/ADt of excess heat suitable for a PIvap besides the 2.6 GJ/ADt of pinch violations. The pinch violations could be transferred to excess heat, but some pinch violations were cost effective to solve. A suggestion where 1.1 GJ/ADt of pinch violations are solved and 1.6 GJ/ADt of excess heat are extracted is presented. If the excess heat is used in a 7 effect PIvap with integrated stripper and increased dry solids content, steam savings of 2.7 GJ/ADt could be made in the evaporation plant. Together with the pinch violations and opportunities for improved soot blowing, the total steam savings from the suggested measures were 4.5 GJ/ADt or 35%. The amount of steam savings and associated costs were similar to the ones in the soft-wood model-mill. Hence, no significant differences could be found for the opportunities to implement PIvap in the hardwood mill compared to in the soft wood mill. The existence of a pre-evaporation plant, however, showed to hinder introduction of PIvap, since a pre-evaporation plant uses excess heat, and uses it ineffectively compared to a PIvap. Hence, the pre-evaporation has been removed in the suggestion for integration presented here.

Energy saving

Pulp mill

Process integration

Evaporation plant

Pinch analysis


Erik Marcus Kristian Axelsson

Industrial Energy Systems and Technologies

Catherine Laaksometsä

Industrial Energy Systems and Technologies

Marcus Olsson

Industrial Energy Systems and Technologies

Thore Berntsson

Industrial Energy Systems and Technologies

Conference PRES 07, Ischia Island, Italy


Subject Categories

Energy Engineering

Paper, Pulp and Fiber Technology

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