Mathematical Modelling of Vertical Roller Mills

Abstract

In this study, it was aimed to develop a mathematical model of vertical roller mills which have found an application in the industry with high energy efficiency. With this aim, pilot scale and industrial scale grinding tests were performed for various materials. During the pilot scale studies, mobile vertical roller mill unit and conventional vertical roller mill were used. Mobile unit has two grinding mode: overflow and airswept. In overflow mode, there is a two-stage air classification system, which is separate from grinding part. This design enables to collect samples from grinding and separation parts, individually. Data obtained from overflow mode grinding tests provided the basis of the modelling studies. After grinding tests, particle size distributions of the collected samples during the sampling studies and fresh feed samples were subjected to bed breakage tests under compression. As a result of the characterization tests, breakage distribution functions and material indices of the samples calculated to use in the model. Within the context of the modelling studies, vertical roller mill was divided into two section as grinding and separation. Model parameters were back calculated for each operation. Then, relationships between model parameters and operational variables were investigated. Obtain correlations were defined by mathematical equations and new modelling approach was developed for vertical roller mills. Developed model structure were tested on pilot scale grinding test data by simulation. In consequence of the simulation studies, it was concluded that the estimation accuracy of the developed modelling approach is successful.