COMPUTER-SIMULATION OF A BLEACHED KRAFT PULP AND PAPERBOARD MILL

This paper describes the use of GEMS to simulate the production of pulp and paperboard at the Potlatch Corp. Mill, Lewiston, Idaho. Two examples of the use of GEMS as an aid in the analysis of proposed process modifications are also discussed. In the reported experiments, process stream flow rates (measured with a portable sonic flowmeter) and chemical analysis (specific ion electrode techniques) were combined with mill operation data (log sheets) and conventional analytical data to validate the simulations and establish water, pulp, chemical, and energy balances for the existing operating conditions. The simulation was then used to aid in the analysis of proposed modifications to the mill. Two alternatives considered to effect a reduction in the mill's energy requirements and its environmental impact were the maximization of blowheat utilization and partial bleach plant closure.