Improving Mill Energy Efficiency

Fuel and power costs are continuously increasing, and virtually all manufacturing facilities are looking for relief. This article describes a retrofit project in a 1980 vintage market pulp mill, the purpose of which was to improve mill energy efficiency at a minimum cost without disrupting or modifying the existing operations. Many pulp and paper mills, particularly in the southeastern united states, can produce significant and sometimes even excess steam. This steam is used for the process needs and area heating and, particularly in mills constructed before the mid 1980s, to power mechanical drive turbines for large variable-speed loads. The advent of reliable and competitively priced electric adjustable frequency drives (AFDs) has provided an alternative to turbine drives and thus presents a choice for new mill designers as well as for personnel involved in optimization of existing, somewhat older, facilities.