Opportunities for Heat Integration of Biomass-based Fischer-Tropsch Crude Production at Scandinavian Kraftliner Mill Sites

Abstract

This paper investigates the potential for production of Fischer-Tropsch (FT) crude at a typical pulp and paper mill producing kraftliner. Heat integrated FT crude production, where excess heat from the FT crude process is used to produce steam for the mill’s steam network, is evaluated for different levels of mill heat demand. The paper presents performance indicators, including wood fuel-to-FT crude efficiency, greenhouse gas (GHG) balances and production cost for FT crude, for co-located production of kraftliner and FT crude. These results are compared to corresponding performance indicators for FT crude production heat integrated with a mill producing fine paper, and stand-alone FT crude production, presented by the authors in a previous study. The results show that a typical kraftliner mill, in contrast to a typical fine paper mill, has a net steam demand even if large investments are made in steam saving measures. A kraft pulp and paper mill with an annual production of 417,000 ADt of kraftliner requires excess heat from an FT crude plant with 80–270 MW of wood fuel (LHV) input, depending on the heat demand at the mill. The wood fuel-to-FT crude efficiency, GHG emissions balances and production costs for FT crude are similar for heat integration in kraftliner and fine paper mills. The comparison of heat integrated and stand-alone FT crude production indicates higher wood fuel-to-FT crude efficiencies and lower production costs for heat integrated FT crude production. The reduction of GHG emissions is strongly affected by the assumed marginal electricity production technology, where heat integrated production benefits from low emitting electricity production technologies.