Heat integration opportunities in average Scandinavian kraft pulp mills: Pinch analyses of model mills
Journal article, 2006

Within the FRAM programme, two models of average Scandinavian mills producing bleached market pulp have been analysed from an energy perspective. The aim was to explore the opportunities for heat integration in order to create a steam surplus. The steam surplus gives opportunities for increased power generation or lignin extraction. The technical and economic consequences of using the steam surplus in this way are explored in a continuation of this project. Two different approaches for creating a steam surplus have been investigated: 1) conventional measures and 2) processintegrated evaporation (PIvap). The former approach includes improved heat integration and new equipment. The latter approach means that excess heat from the mill is used for evaporation to partly replace live steam. The two model mills created within FRAM both produce 1000 ADt/d softwood pulp. The mills differ in the level of water usage, since it is expected that the amount of excess heat for PIvap will increase with decreasing water usage. By investing 11 M€ in conventional measures it is possible to create a steam surplus of 53 MW (about 26% of the total consumption), independent of the level of water usage. For the PIvap approach, the level of water usage matters, since there is more excess heat for PIvap in the mill with lower water usage. As a result, the total steam surplus with the PIvap approach differs in the two mills: up to 52 and 56 MW, respectively. Hence, the steam savings for the PIvap approach are similar to those in the approach with conventional measures; and so are the investments needed (10-12 M€). Even though the two approaches give approximately the same savings with the same investment, the PIvap approach might be easier to implement in an existing mill.

Kraft pulp mill

Mill closure

Heat integration

Steam surplus

Process-integrated evaporation

Steam savings

Energy efficiency.

Pinch analysis

Author

Erik Marcus Kristian Axelsson

Industrial Energy Systems and Technologies

Marcus Olsson

Industrial Energy Systems and Technologies

Thore Berntsson

Industrial Energy Systems and Technologies

Nordic Pulp and Paper Research Journal

Vol. 21 4 466-475

Subject Categories

Energy Engineering

Paper, Pulp and Fiber Technology

DOI

10.3183/NPPRJ-2006-21-04-p466-475

More information

Created

10/6/2017