LONG FEEDBACK COMPENSATED KAPPA FACTOR CONTROL: PART II OF PROCESS OPTIMIZATION AT ROCK-TENN COMPANY, DEMOPOLIS ALABAMA MILL

摘要

Rock-Tenn Mill Company, LLC in Demopolis Alabama has two fiberlines: one dedicated to HWD pulping & bleaching and the other dedicated to SWD pulping & bleaching. The mill installed an online Kajaani Kappa Analyzer and implemented Compensated Kappa Factor Control for the D0 and Dl stages for both fiberlines. On the Hardwood fiberline, because its production rate is more than three times the Softwood production, the mill installed filtrate pistons for pH control in every bleach stage and an inline brightness sensor (a Cormec-I after the Dl stage to the Hardwood HD Bleached Storage). Also on the Hardwood fiberline, the soon-to-be obsolete inline Brightness and Residual sensors were upgraded to I-series sensors feeding the D0 and Dl stages. The mill plans to make the same modifications to the Softwood fiberline. After bleach plant process optimization and implementation of Kajaani long feedback control strategies (CEKappa feedback control to D0 ClO_2 dosage for both fiberlines and Dl final brightness feedback control to Dl dosage for HWD bleaching), the mill realized 11.6% C1O_2 and 24% Caustic savings from baseline while bleaching HWD pulp and 16.8% C1O_2 and 24% Caustic savings from baseline while bleaching SWD pulp. This paper describes the evolution in bleaching measurements and controls at Demopolis that have resulted in placing Demopolis among the lowest cost bleach plants for both HWD and SWD manufacturing in North American benchmarking.