Austin, TX—Emerson Process Management was recently selected by Alcan to help improve processing operations at its Alumina and Specialty Chemicals facility at the Jonquiere Complex (Quebec, Canada). The plant produces specialty hydrates, which have to be manufactured with stringent quality requirements in a process with challenging dynamic process control applications.

Previous loop-tuning work had been undertaken with little improvement. Alcan hired Laurentide Controls and Emerson's Process Solutions division in February 2003 to improve washing and drying operations in the plant. Using Emerson's EnTech Diagnostic ToolKit, the team found that process optimization would more likely be achieved by revising Alcan's process control strategy and design than by loop tuning.

Following initial modifications in the mill's Provox system, Alcan reduced dryer temperature variations by 60% and increased production by 12%. This production increase is worth more than $1 million per year. The control loops were re-tuned very conservatively by using the systematic Lambda method. The reduction of variability at its source—before it reaches the PID controller—allowed for a much more robust tuning and reduced resonance to a minimum.