The modelling and simulation of dissolution of sucrose crystals

Abstract

A population balance based dynamic model was made for dissolution of sucrose crystals. The model was used for simulation and parameter estimation. The calculation sequence was designed so that experimental measurement data could be used as inputs. The solution was based on the use of numerical method of lines. The experiment was started with a sample from a single sieve. Then this sample was put into a tank filled with undersaturated solution. The dissolution system was assumed to be well-mixed and mass transfer limited. The population balance partial differential equation was solved using fifth order finite difference approximations for the particle size derivative. Then the partial differential equation was reduced to a set of ordinary differential equations. The results of the model were the masses of components and the crystal size distribution (CSD). The Fortran program was written in Modest. Modest was used to solve the differential equation set, optimise parameters and create the user interface. Only the diffusion growth rate parameters were optimised. The target was to fit the experimentally determined mass of crystals with that of the calculated population densities. The goal of the simulation and parameter estimation was to test whether reasonable results for CSD and mass growth dynamic behaviour could be achieved with the measurement data available. The results of the model are presented and possible reasons for deviations between the model and experiments are discussed.