Modeling of Chemical Vapor Deposition of Pyrolytic Carbon in a Gas-Spouted Bed Reactor

Spouted beds are used in chemical vapor deposition as they provide good solid mixing, thereby enhancing high mass and heat transfer rates. In the present study, investigations on the kinetics of a coating process by chemical vapor deposition were carried out in a spouted-bed reactor. Pyrolytic carbon coatings were studied by thermal cracking of acetylene mixed with carrier gas argon at 1350 °C. A theoretical model was proposed based on the mass balance of the precursor in the spout and annulus zones at isothermal condition, and the model equations were solved using MATLAB (version 7.1) software. The effect of the operating gas velocity, initial static bed height, and acetylene concentration on the coating rate was examined experimentally and also by simulation results. The simulated results agreed well with the experimental results. Model equations used for simulation were utilized to evaluate the reaction rate constant and radial gas diffusion coefficient and then to study the effect of spout diameter, operating gas velocity, and precursor concentration on the overall conversion of the precursor.