Mechanism Analysis and Parameter Optimization of a Residual-Film Dry Granulation Device

Residual plastic film recovered from arid farmland in Northwest China cannot be processed by water-washing melt granulation, because dry cleaning leaves too much soil and straw in the film. This study optimizes a self-developed dry granulation device that converts such film into particles by friction-induced heating. First, the feeding, cutting and stirring processes were analyzed to identify the moving-cutter rotational speed, the fixed-cutter edge angle and the stirring-blade upper-end length as the key structural parameters. Second, Fluent, LS-DYNA and EDEM simulations were used to determine their reasonable ranges. Third, single-factor and Box–Behnken tests were carried out with the residual-film utilization rate (Y1) and granulation rate (Y2) as responses, and regression models were fitted (R2 = 0.984 and 0.989). The optimal combination was 665.86 r/min, 45.58° and 97.24 mm, for which the models predicted Y1 = 92.77% and Y2 = 95.58%. Field verification gave 91.71% and 94.08%, with relative errors of 1.14% and 1.57%. The results provide a basis for the design and parameter selection of dry granulation equipment for residual film.