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Measures for increased energy efficiency at Iggesund mill - Pinch analysis of the pulp production lines at a paperboard mill

Karin Glader
Göteborg : Chalmers tekniska högskola, 2011. 62 s.
[Examensarbete på avancerad nivå]

Swedish pulp and paper industry is facing a future with increased competition from manufacturers with access to faster-growing raw materials, cheaper labour and more modern mills. To survive and stay competitive, investments in more efficient production could be one option. This thesis addresses the potential for increased energy efficiency at Iggesund Paperboard - Iggesund mill. The mill is an integrated pulp and paperboard mill that is almost self-sustaining in energy aspects, producing most of its own need for electricity, and is a provider of heat to the local district heat system. To evaluate the energy situation, pinch analysis was used for identifying and evaluating the energy saving potential. The analysis is limited to the pulping process and the chemical recovery cycle. A new recovery boiler will be in place by June 2012 and the energy situation has been adapted to these future conditions. Based on data collected on site, today’s energy situation was mapped and the potential for energy savings evaluated. The author can conclude that energy savings are possible. The pinch analysis shows that up to 18 MW of steam theoretically can be saved in the future process. Besides this there is also a wish to reduce the use of primary heat in the district heat production. Available heat sources for process integration are mainly flue gases, hot bleach plant effluents and flash steam. In order to partly realise this saving potential, two stream saving retrofits are presented. By changing the preheating of boiler feed water, 7.9 MW of steam can be saved, which is equal to 2.6% of the mill’s total steam demand. If a more extensive retrofit is constructed the savings increase to 13 MW, which is equal to 4.4% of the total steam demand. Increased process integration will reduce the capacity for district heat production but still the more extensive retrofit has the opportunity to produce 44% of the needed district heat peak load. Furthermore, this thesis also presents a retrofit evaluating the maximum potential for district heat production that aims to produce 22 MW of peak district heat, but without possibility for other steam saving actions. Finally, it is also concluded that when comparing the mill to others, there is a potential for reduction of the steam demand at the wood yard.

Nyckelord: Pinch analysis, Integrated pulp and paperboard mill, Energy efficiency, Steam savings, District heat

Publikationen registrerades 2011-08-12. Den ändrades senast 2013-04-04

CPL ID: 144146

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