(701d) Value Added Pulping

Pulp for paper furnish has been the dominant product in the Kraft pulp mills. The remaining 50-60% of the wood is burned for energy and chemical recovery. Sulfite pulp mill provides better platform for a forest based biorefinery. New sulfite based biorefinery concept is presented, integrating well proven commercial technologies. Ethanol is significant co-product increasing the revenues by 50% at low additional energy input.

American Value Added Pulping (AVAP?) utilizes alcohol sulfite cooking liquor to fractionate softwood chips into three lignocellulosic components. An addition of alcohol speeds the pulping, while preserving the cellulose strength. Volatile cooking chemicals are stripped and reused in the cooking process at a high recovery rate. Lignosulfonates are precipitated and burned to produce process energy. The remaining liquid fraction contains hydrolyzed hemicelluloses. This sugar rich solution is fermented to yield annually up to 22.6 million gallons of bioethanol. The value of converted hemicelluloses is 4-5 times greater for society as ethanol than as presently burned. Biomass from the surrounding wood processing plants as well as logging residues can provide energy self-sufficiency for the mill.

Process integration and efficient recovery of chemicals are the cornerstones for the low overall cost. Because ethanol processing occurs concurrently with pulping, the heat and chemical input are split between the two products, without sacrificing the yield on either product. Flexibility to swing yield between the two products provides financial stability over the market conditions. Additional biofuels and chemical are obtainable from the process if the economics are favorable.

AVAP? process design is presented in the context of converting an existing uneconomic pulp mill to a biorefinery. This presents a large commercial potential with ageing pulp mills that will have to replace a $100+ million recovery boiler in the near future