Debottlenecking the Recovery System of Soda Pulp Mills by Lignin Recovery and Wet Oxidation-Application to Non-Wood..., 2000 Pulping / Process & Product Quality Conference Proceedings

J. H. Lora, A. Abacherli, F. Doppenberg--The evaporators, recovery boiler, and associated equipment are frequently the bottleneck of existing pulp mills since they are fairly capital intensive and sensitive to economies of scale. As a result, it is difficult to economically accomplish small incremental capacity additions based on evaporation followed by combustion in a recovery boiler. This problem is worse in non-wood fiber pulp mills, which are typically small in capacity, and often have difficult to handle spent liquors. In this paper lignin recovery and wet oxidation are proposed as liquor processing alternatives that advantageously permit the addition of small incremental capacity to existing soda mills that process non-wood fibrous raw materials. For the addition of 50 ton/day of pulp to a 250 ton/day pulp mill these technologies allow the cost of production of the incremental pulp to be competitive with the base case. The technologies offer several additional advantages. For instance, lignin recovery results in enhanced revenues from lignin sales, while wet oxidation yields higher net steam production, built-in capability to purge silica from the liquor cycle, and reduced effluent load.