Best case utilization of residual forest biomass streams in the pulp and paper industry

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Webb, Emma
Pulp and Paper
Drawing on Canada’s abundant forest resources, the Canadian pulp and paper industry has long been a significant contributor to GDP and a major consumer of industrial energy. In recent years, however, the industry has faced declines due to declines in paper consumption and increased overseas competition. Our study seeks to examine how the industry can be revitalized through the exploitation of waste residue streams for chemical and energy production. The Millar Western BCTMP mill at Whitecourt, AB and the Tembec (now Rayonier) sulphite mill in Temiscaming, PQ were examined, and flow streams and waste residue generation were identified and quantified. At the Tembec mill, daily flow data was used to make predictions on quantities and consistencies of various residual streams. The potential of these flows to support chemical and energy production at the mills was explored. Using natural gas cost as a proxy for price, the economic value of residual biomass as energy was determined and contrasted against potential value from chemical products. Although limited by lack of compositional analyses of residue streams and incomplete economic data, use of pilot plant examples facilitated this comparison. Waste residue streams were identified at both sawmill and pulping phases. Sludge flow was recognized as having the greatest potential for exploitation; it was the largest stream producing on average between 260 and 440 tonnes per day, and currently not being used at either mill for economic gain. Analysis of Tembec data displayed that daily flow streams were highly variable in their values. Correlation analyses, however, suggested that practices such as stockpiling could be exploited to decrease this variability in daily quantity. ii It was found that the value of biomass as energy was highly volatile, fluctuating from C$ 34-153/ tonne of biomass during the study period. Such value was additionally seen to be highly sensitive to the heating value of the biomass, which can be expected to change with the moisture content and type of residue. Similarly, based on literature reviews, exploitation of residues for chemical production of NCC and isolated lignin was determined to plausible, and quantities from sludge were deemed capable of meeting pilot scale levels. Further compositional analyses, investigation into dewatering processes, and research into the economics is needed to consider scaling these chemical productions to a larger level.
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