Converting a kraft pulp mill into a multi-product biorefinery – Part 2: Economic aspects

Conversion into dissolving pulp production is an interesting pathway for kraft pulp mills experiencing decreasing marginal revenues. In this two-part study, the technical and economic consequences of the conversion have been investigated.In Part 1, the energy aspects of converting into dissolving pulp production were studied, as well as the consequences on the by-product and pulp production capacity of the converted mill.In this paper, the economic performance of different process configurations is evaluated. Our results indicate that the price of dissolving pulp and the pulp production capacity of the mill have the largest influence on the overall profitability. Accordingly, in order to achieve high profitability, it is necessary to debottleneck the mill’s capacity for pulp production. Debottlenecking the recovery boiler by upgrading capacity and increasing power generation requires large investments and downtime costs but can be profitable if the price of electricity is high. Debottlenecking by means of lignin separation can nevertheless be more interesting if lignin is valued high or if investment capital is limited. Regardless of the way the recovery boiler is debottlenecked, a higher level of heat integration is always more attractive than a lower, simpler level of heat integration.