Modellering och optimering av TMP:s kristallisator

Sammanfattning: The aim of this thesis work was to create a model describing the crystallization process of sodium formate and to calibrate this model to real process data. Sodium formate is a by-product formed during the production of Trimethylolpropane (TMP). The model used is based on the population balance equation and include crystallization mechanisms such as particle nucleation, growth and agglomeration. The model created will describe the particle size distribution of sodium formate crystals and the crystals will be divided into different classes according to size. The program used for the simulation is Scilab 5.5.2. The particle size distribution is expressed in volume%. After calibration, the created model differ some from real process data. The number of crystals of the smaller ones is too low and the large crystals are too many. Also the width of the distribution is too small. The best simulation, namely the one with the smallest deviation from real process data, was when the crystals where divided into 10 size-classes. The deviation/class where then ±5.8 volume units. A proposal for further work is to extend the model and add a term describing breakage of crystals. This will lead to more small crystals, less of the bigger ones and a wider distribution. Only one particle size distribution experiment has been done and to be sure that this distribution agrees with the distribution in the TMP-crystallizer, more experiment needs to be executed.