Pinch analysis of Billerud Karlsborg, a partly integrated pulp and paper mill

Abstract

The awareness of climate change together with limited resources of fossil fuels are driving forces for energy efficiency improvements and a shift towards renewable resources. For energy intensive industry like the pulp and paper industry, the incentives are even stronger. A useful tool for identifying potential for energy savings at an existing site is pinch analysis. Presented in this thesis is a pinch analysis of Billerud Karlsborg, a partly integrated pulp and paper mill. The plant’s potential for energy savings has been evaluated using information and data collected at the mill. The aim has been to identify the potential for energy efficiency improvements, focusing on possibilities to save steam. The potential for energy savings at Billerud Karlsborg has been identified to 18.5 MW, which accounts for 12% of the present steam demand. Parts of this can be achieved through replacing steam with hot effluents from the bleaching and evaporation plant, when fulfilling heating demands. Two retrofit proposals are presented, one were fewer changes are made and one which is more comprehensive. The latter is an extension of the first. In the light retrofit, 5.8 MW of steam is saved through utilization of hot effluents. The cost for this retrofit is 0.13 M€ per MW of saved steam. In the rigorous retrofit further steam savings are achieved through improvements in the hot and warm water system summing up to a total of 11 MW. The cost for this retrofit is 0.14 M€ per MW of saved steam.