(493a) Simulation of the Selective Oxidation of N-Butane to Maleic Anhydride in a Riser/Regenerator-System

A simulation tool is presented that is able to estimate the behavior of fluidized-bed reactors. A population balance approach is used to determine the particle size distribution within the reactor in stationary state. The model allows to describe the individual fate of particles in terms of attrition (abrasion and shrinkage) and transport effects. The fluidized-bed reactor modeling is based upon the Werther and Wein model for bubble growth [1] and simple kinetic approaches. The implementation within the framework of a flowsheet simulation software for solids processes allows for the flexible coupling of process models. As an example the simulation of the selective oxidation of n-butane to maleic anhydride in a riser/regenerator system is presented and compared to measurements by Golbig and Werther on the laboratory scale [2]. The arrangement has been described by coupling a riser model with a bubbling fluidized-bed model. The oxygen load distribution on the catalyst particles is taken into account. The simulation results turn out to be in good agreement with the measurements. Scale-up calculations show that high solids circulation rates are necessary. The importance of the catalyst's attrition-resistance and oxygen-load capacities for the economic success of the investigated technology is illustrated.

[1] Werther J, Wein J. Expansion behavior of gas fluidized beds in the turbulent regime. AIChE Symposium. Series. 1994; 301:31-44.

[2] Golbig KG, Werther J. Selective synthesis of maleic anhydride by spatial separation of n-butane oxidation and catalyst reoxidation. Chemical Engineering Science. 1997;52:583-595.