Heat integration opportunities in an average Scandinavian fine paper mill: model study and comparison with a market pulp mill

摘要

The pulp and paper industry has a potential for significant energy savings, as shown by many studies on both market pulp mills and integrated pulp and paper mills. In this study, we compare the opportunities for energy savings through heat integration in the two mill types. To do this systematically, we used model mills with an identical pulp mill connected to either a pulp dryer or to two paper machines. An energy analysis of the integrated mill showed that there are steam-saving opportunities of about 16%, which enable increased electricity production or fuel savings in the form of reduced bark burning. For electricity production, the break-even electricity price was 25-50 EUR/MWh depending on economic conditions. For fuel savings, the break-even bark price was 5-11 EUR/MWh depending on economic conditions and electricity price (the electricity production decreased when fuel was saved). When comparing the integrated pulp mill with the market pulp mill, the authors identified inherent differences that influenced the steam-saving opportunities in favor of the market pulp mill, implying a payback period about 0.4 years longer in the case of electricity production in the integrated mill. In the case of fuel savings, however, the integrated mill would have significantly better profitability, because fuel savings in the market pulp mill had to be in the form of lignin extraction from the black liquor, which would entail additional investment and operating costs.