Numerical study of wet plastic particle separation using a coupled DEM-SPH method

摘要

The separation of different kind of plastic particles is required in theprocess of waste recycling. For the separation drum processes passed through bya liquid are applicable. Thereby the separation is based on the principle thatparticles either sink or float in a liquid depending on their densities. Inthis study the aforementioned process is numerically analysed for theseparation of polyethylene terephthalate (PET) from polypropylene (PP)particles. The Discrete Element Method coupled with the Smoothed ParticleHydrodynamics method (DEM-SPH) is used for modelling purposes. The employmentof the SPH for the modelling of the liquid let us exploit the strong side ofthis mesh-less method, namely, the relative easiness to model large movementsof the fluid together with free surfaces and moving boundaries. The usedtheoretical model is presented and validation tests are performed, where adam-break problem is considered as an example. Simulations of the plasticparticle separation in the rotating drum are performed thereafter. Theinfluence of the different operational and design parameters, such as therotational velocity, the feed rate, the number of lifters etc., on theresultant purity of the plastic is estimated. It is expected that in the futurethe performed analysis will allow to optimise drum separation processes.