Pinch analysis of a partly integrated pulp and paper mill

Paper in proceeding, 2011

The pulp and paper industry, with its wood biomass feedstock, has promising opportunities to become a key player in the biorefinery arena. A successful implementation of biorefinery pathways requires optimization of the energy system through process integration, and can lead to both increased and diversified revenues as well as a reduction of global CO2 emissions. This paper presents the results from a pinch analysis of a partly integrated Kraft pulp and paper mill. The objective was to identify the potential for energy efficiency improvements, focusing on possibilities to save steam. Another objective was to identify practical retrofit solutions for the mill heat exchanger network and to estimate the costs for the required investments. The potential for energy savings at the mill is estimated at 18.5 MW, i.e. 12% of the current steam demand. Two alternative retrofit options are presented in the paper. A straightforward retrofit that is easy to implement enables 5.8 MW of steam to be saved at a cost of €0.13 million per MW of saved steam. A second more extensive retrofit option is also presented which could achieve steam savings of 11 MW at a cost of €0.14 million per MW of saved steam. Assuming that the steam savings lead to a reduced use of bark fuel in the power boiler, the payback period of both energy saving retrofit investments is estimated to be less than about 16 months.