Seasonal Variation in Wood: Perceived and Real Impacts on Pulp Yield

摘要

Frequently, mills will experience substantial variations in reported pulp yields per green ton of wood over the course of a year. Spring months tend to require higher levels of wood consumption to produce the same amount of good quality pulp. The level of seasonal changes and seasonal reproducibility of wood moisture in chips are examined. Seasonal changes in the amount of bark, pins, and fines in the chips going to the digester are also examined. Other potential seasonal accounting function impacts upon reported pulp yield and costs are also examined. Assuming a 1000 TPD mill with a nominal wood cost of $45/green ton, these seasonal changes can account for almost a $600,000/month variance between the best and worst operating month. A change of about 0.5 green tons of additional wood per ton of pulp has to be processed during the worst operational month.