Industrial Lime Kiln Computer Dynamic Simulation for Improving Efficiency

Abstract

The mathematical model of a pulp mill lime kiln and computer dynamic simulation are presented. The set of hyperbolic partial differential equations describing the chemical reactions, the mass balance, energy balance and axial solids transport is described. In order to obtain a model with an acceptable degree of complexity, the radial and angular variations for the solid and gas temperature equations are neglected. Since the wall represents an important thermodynamical link between kiln environment and surroundings the radial kiln wall variation was considered in the model. The objective is the optimization of the kiln operating conditions in industrial environment in order to increase product quality, decrease energy consumption and improve environmental conditions. The set of partial differential equations is solved by a finite difference method and by a finite element orthogonal collocation method with cubic piecewise polynomials as the approximating functions. The respective computational cost are compare. The results obtained by numerical methods are discussed in comparison with experimental data. Using the model, a study of energetic kiln behaviour is presented. The influence of various kinds of parameters on the energy process consumption is discussed. It is expected that this investigation will allow to enhance the knowledge of kiln behaviour and will be used for a further non conventional control approach.