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

Abstract

The separation of different kind of plastic particles is required in the process of waste recycling. For the separation drum processes passed through by a liquid are applicable. Thereby the separation is based on the principle that particles either sink or float in a liquid depending on their densities. In this study the aforementioned process is numerically analysed for the separation of polyethylene terephthalate (PET) from polypropylene (PP) particles. The Discrete Element Method coupled with the Smoothed Particle Hydrodynamics method (DEM-SPH) is used for modelling purposes. The employment of the SPH for the modelling of the liquid let us exploit the strong side of this meshless method, namely, the relative easiness to model large movements of the fluid together with free surfaces and moving boundaries. The used theoretical model is presented and validation tests are performed, where a dam-break problem is considered as an example. Simulations of the plastic particle separation in the rotating drum are performed thereafter. The influence of the different operational and design parameters, such as the rotational velocity, the feed rate, the number of lifters etc., on the resultant purity of the plastic is estimated. It is expected that in the future the performed analysis will allow to optimise drum separation processes.

Numerical Simulations of Liquid-Solid Flows in A Vertical Pipe by MPS-DEM Coupling Method

“…Some small discrepancies of the leading front of the sediment between the numerical results and experimental data can be observed. The main reason may be that the physical parameters of solid phase in simulation is roughly estimated (Sun et al, 2013;Markauskas et al, 2018). In general, liquid−solid two-phase can be simulated by MPS−DEM solver accurately.…”

Notes on Common Misconceptions in Microplastics Removal from Water

“…Density separation was further developed (various extraction liquids, leaching in H 2 O 2 , flowing liquid, stirred-shaken sediment in gravitational or centrifugal field, in counter-current gas = foam flotation or elutriation) and high separation efficiency was achieved using a drum separator [101], or by electromagnetic density separation in a ferro liquid, which can change its density according to EM radiation (Kress and Franchetti [102]). Some of the plastics may have very similar density to water and that could be a major drawback of the practical application of such method.…”

Discrete element modeling of the machining processes of brittle materials: recent development and future prospective

“…In dealing with the problem of fluid-solid two-phase flow, in addition to the DEM-CFD coupling technology previously mentioned, many scholars have been working on the coupling technique of the smooth particle hydrodynamics method (SPH) and the DEM in recent years. To numerically analyze the coupling problem of solidliquid two phases [184][185][186][187][188][189][190]. Both SPH and DEM are meshless methods, which have certain advantages in solving problems such as large deformation.…”