Increasing crude tall oil yield

In the kraft pulping process for softwoods and hardwood, tall oil recovery is an important part of making profit. During the past 10 years, crude tall oil (CTO) production in the U.S. and Canada has dropped. Estimated CTO yield from fresh Canadian pine is 36-40 lb/a.d. ton and from Southern U.S. 70-80 lb/a.d. ton, while the average yield of CTO is approximately 40% of available tall oil in pine wood. Besides low yield, many pulp mills fail to achieve a CTO quality that lives up to market expectations. The moisture content of CTO is reported to vary widely (1.5-3.5%), whereas it should not exceed 1.5% for marketable quality. The acid number of CTO varies in the range of 135 to 150, whereas industry standards are 145-150. At present the average sale price of CTO is approximately $150/ton. By upgrading existing plants, the yield can be increased, resulting in additional revenues. Thus, if a batch acidulation plant is replaced by a continuous acidulation plant, the yield will increase by approximately 15-50%. The capital required for installing a continuous system is approximately $1.1-1.5 million for a 500-a.d. ton/day pulp mill, requiring a payback period of approximatley 5-7 years. 7 references.