Long-term energy-efficiency improvements in the paper and board industry

A method for identifying and characterizing technologies that can improve the energy efficiency in the long term is described and applied to the paper and board industry. Current papermaking processes require 3-9 GJ heat per tonne of paper, mainly for the removal of water that is added initially to the fibers, and 1.3-2.9 GJ electricity/tonne. The selection of technologies is based on the results of an exergy analysis of a paper mill. Seven relevant technologies are described. It is concluded that in the future paper-mill a combination of new pressing and drying techniques, latent heat recovery systems, and a number of minor improvements can reduce the specific heat demand by 75-90% compared to the current average. The specific electricity consumption will remain about equal or will increase slightly. Investment costs will be lower than for conventional paper-making processes. Benefits other than energy-efficiency improvement, e.g., an improved paper quality or a higher production rate, are the driving forces for the development of the technologies. (C) 1997 Elsevier Science Ltd.