Influences of Short-term Variations on Energy-Saving Opportunities in a Pulp Mill

Significant opportunities for energy savings are identified in the hot and warm water system of a kraft pulp mill. Short-term variations in the process are studied in order to identify and quantify the influences of these variations on the energy-saving opportunities. Daily and ten-minute averages of measured data are used as varying input data in a heat exchanger network with fixed heat transfer areas. When the short-term variations are considered, the total energy savings are decreased by about 10%. The steam-saving opportunities correspond to at least 5% of the mill's total steam use, when the short-term variations are considered. At least 65% of the influences of short-term variations are detected already when the seasonal variations are considered.