BLEACH PLANT CLOSEUP AND CONVERSION TO TCF - A CASE-STUDY USING MILL DATA AND COMPUTER-SIMULATION

Process simulation and mill data from Louisiana-Pacific's Samoa, CA, m arket pulp mill have been used to evaluate the conversion of a convent ional oxygen-delignified softwood bleach plant to totally chlorine fre e (TCF) bleaching based on hydrogen peroxide. During a recent mill TCF closeup run, substantial reductions were made in water use, steam con sumption, and sewer leading. Thirty-one percent of the bleach plant or ganic dissolved solid material, normally lost to the sewer during conv entional chlorine bleaching, was recycled to the recovery boiler. An e conomic evaluation comparing the TCF process, conventional chlorine bl eaching, and 100% ClO2 substitution (ECF) is presented. TCF bleaching costs US$ 26-29/a.d. metric ton pulp more than ECF bleaching.