Dynamic Modeling of a Coal Mill for Simultaneous Dynamic Data Reconciliation and Parameter Estimation

In comparison with other gaseous and liquid fossil fuels used in power production, a coal fired power plants requires additional equipment for fuel preparation. A medium speed mill is usually a preferred equipment which serves in grinding and drying of the raw feed coal. Due to the high recycle of coal particles within a medium speed coal mill, the mill performance is sensitive to the efficiency of grinding and classification operations within mill. The goal of this research is to study the performance of the milling system and develop a method to estimate some of the unmeasured variables, which include pulverized fuel flow, fuel fineness, and mass of coal accumulated within mill. In this work, a dynamic model of Vertical Spindle Mill (VSM) is developed using empirical formulations of size- reduction, and classification. While mass and energy balances are used to simulate moisture evaporation from coal particles. With the model developed in Aspen Custom Modeler, a simultaneous data reconciliation and parameter estimation experiment is setup for validating mill model using the measurements obtained from Industrial Partner Plant (IPP). The model is then used to study the performance of the mills operated in parallel, where the performance measure is obtained by calibrating and then comparing the efficiency parameters related to particle separation and grinding