Numerical Simulation Of The Coating Process Of Ellipsoidal Tablets

In pharmaceutical industry,coating is an important unit operation in the process of coated tablet production.The quality of the coating equipment and process directly affect the quality of the coated tablets.Most of the process parameters of tablet coating can only be judged by production experience,which is easy to produce operational errors and thus it is difficult to ensure the stability and effectiveness of product quality.In recent years,with the rapid development and wide application of computer technology,Discrete Element Method(DEM)has become an effective numerical method to simulate the tablet coating process,which can increase people's understanding of the coating process,and then can improve the coating equipment and processes.In this paper,a common used pan coater is investigated and the simulation of the ellipsoidal tablet coating process is realized by adopting the discrete droplet method(DDM)spray model within the non-spherical DEM framework.The main research work is as follows:(1)The super-ellipsoid DEM model was used to describe the ellipsoidal particles,and the comparison was made with the ellipsoidal particles modeled by multi-sphere DEM model.The above two DEM models,super-ellipsoid DEM and multi-sphere DEM model,were adopted to simulate the process of particle packing in a container,particle flow in a rotating drum,and particle discharge in a hopper,respectively,and the corresponding experiments were carried out.Comparing the results of both simulations and experiments,it can be obtained that numerical simulation results of the super-ellipsoid DEM model are more close to the experimental results and the computational efficiency is higher,which confirms the high efficiency and accuracy of the super-ellipsoid DEM model.(2)The DDM spray model based on non-spherical DEM was proposed,which was used to simulate the coating process of ellipsoid tablets in a pan coater,and the corresponding coating experiment was performed for the comparative study.The numerical simulation results are basically consistent with the experimental results under the same operating conditions,confirming the feasibility and accuracy of the DDM spray model.(3)The influence of different operation parameters such as pan rotational speed,pan tilt,spray angle,spray flow rate and spray droplet diameter size on the tablet coating mass uniformity was also investigated,and the variation law between the tablet coating uniformity and the operating parameters was obtained.The size of the pan coater was enlarged from the laboratory scale to the industrial scale in order to study the effect of equipment amplification on the tablet coating mass uniformity.The super-ellipsoid DEM model and the DDM spray model in the paper can simulate the coating process of ellipsoidal tablets in pan coater accurately,which provide an effective numerical calculation method for the simulation of tablet coating process in pharmaceutical industry,and can provide technical support for the design of coating equipment and optimization of the process operation parameters.