The potential for steam savings and implementation of different biorefinery concepts in Scandinavian integrated TMP and paper mills

In this paper the potential for steam savings and excess heat levels is analyzed for four Scandinavian thermo-mechanical (TMP) pulp and paper mills, using the Heat Load Model for Pulp and Paper (HLMPP). The results are compared with similar results from previous studies for two other TMP mills. Further, an analysis is made regarding the relationship between the steam consumption and temperature level of excess heat and mill-specific characteristics such as production rate and fresh warm water usage. Based on the results and the analysis, the potential for implementation of different biorefinery concepts is discussed. The results indicate that steam savings of 2–20% can be found in Scandinavian TMP mills. The pinch temperature is rather low, around 20–70 °C for most of the studied mills, compared to the pinch temperature usually found at kraft pulp mills (100–140 °C). Further, two of the mills show an un-pinched Grand Composite Curve (GCC) where the heat demand curve starts close to 0 °C. Thus the potential utilization options for the excess heat are rather limited. The results also show that the level of heated fresh water affects both the steam consumption and the pinch temperature, and thus the potential for efficient integration of different biorefinery processes.

► Steam savings and temperature levels for excess heat were analyzed for 4 TMP mills. ► The theoretical steam-saving potential identified varies between 2% and 20%. ► The pinch (and thus excess heat) temperature is quite low, ranging from 18 to 72 °C. ► Thus possible biorefinery applications for TMP mill excess heat are rare, however. ► Thermal integration with a biorefinery can supply part of the mill’s heating demand.