Process Simulation of Chlorine Dioxide Subsititution, 1991 Forest Products Symposium Proceedings

Modular Analysis of Pulp and Paper Systems (MAPPS) was used to simulate the chlorine dioxide substitution of chlorine in the kraft pulp bleaching sequence. The work, contained in the CSUBD process module, assumed that chlorine dioxide substitution behaved as a competing/parallel reaction sequence. Kinetic parameters and reaction pH were varied as the level of chlorine dioxide substitution was increased. Variation of pH was based on experimental data. Kinetic parameter variables were altered in accordance with literature data on the relative consumption of chlorine and chlorine dioxide during chlorine dioxide substitution. A novel solution technique, the Reverse-Variable Approach, was employed to solve the stiff ordinary differential equations that describe the chlorine and chlorine dioxide kinetic equations.

Simulation case studies were conducted in order to determine the validity of the assumed kinetics and reaction pathways. Process predictions were compared with both literature values and laboratory data. As a result of the development of this process simulation module, the chlorine dioxide substitution reaction may be linked to the rest of the bleaching sequence. Therefore, this important commercial practice may be evaluated through model studies.