Modelling and parameter estimation of reaction kinetics in coal pyrolysis

In order to simulate the reaction processes of industrial coal reactors on computers, the reaction kinetics of small coal particles during pyrolysis have to be investigated first. We consider a reaction model developed by chemical engineers (cf. [9]). This model is based on the ultimate analysis of the original coal particle where the gaseous products voltalize from the coal mass. The model yields a large system of differential equations which describes the whole reaction process at once. As opposed to a well-known model of coal pyrolysis which is frequently used in chemical engineering (see for instance [5]), the reaction rate constants of the proposed model are the only parameters which are unknown and which can be calculated by use of observations taking during a pyrolysis process. The total amounts of the gaseous products depend on the analysis of the original coal mass, and they are computed automatically. In order to solve the O.D.E. parameter estimation problem, we use a numerical procedure which is based on a multiple shooting algorithm in combination with a generalized Gauss-Newton method (cf. [1], [6]). We show that the model has to be reduced first to basic reactions for which parameter estimates can be calculated. By adding more reactions, systematical inconsistencies are detected in the proposed model. Thos are removed by introducing additional boundary conditions at the end of coal pyrolysis and by using some ideas from the classical model. (orig.)Available from TIB Hannover: RN 7879(9606) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman