Molecular weight and its distribution are extremely important quality indices in the polymer production process

however real-time measurement of molecular weight and its distribution cannot be achieved.Dynamic modeling based on polymerization mechanism is an important method for implementing soft measurement.In this study

the polymerization conditions of the ethylene slurry polymerization plant (HDPE) were investigated based on polymerization mechanism

with polymer average molecular weight and its distribution curve as the target

the ratio of hydrogen to ethylene in recycle gas as the decision variable.The results showed large deviation between the simulation results with the average molecular weight as the optimizing target and those of plant analysis.Although the average molecular weight of the polymer could reach the desired quality

the maximum error between the molecular weight distribution curve from simulation and the desired polymer product could be up to 0.092.However

the maximum error was only 0.069 with the molecular weight distribution curve as the target.Therefore

the optimization method with the molecular weight distribution curve as the target is significantly superior to the conventional optimization method with average molecular weight as the target.