Evaluation of Kraft Process Pollution Abatement Strategies by Time Series Analysis of Makeup Records

As part of an ongoing effort to apply the tools of systems engineering to the problems of modeling, controlling, and operating kraft recovery systems, a rather long historical record of chemical makeups to this process has been scrutinized. The data describe the pulp production, makeup of salt cake, and makeup of caustic for a single large pulp mill on a monthly basis over almost nine years from January 1970 to September 1978. In addition to the monthly makeup data, certain other aspects of plant operation are known in a somewhat sketchier fashion. These include the approximate startup dates of two different pollution abatement equipments, an operating move made to reduce emissions, and the nominal operating sulfidity of the mill a t certain related times. These data have been analyzed using techniques ranging from time series analysis to simple stoichiometry in an effort to extract from them estimates of the efficacy of the several pollution abatement moves.