(485d) Modeling and Scale-up of a Hydrochlorination Reaction in a Fluidized Bed Reactor

In the manufacturing process of high purity, electronics-grade silicon, the hydrochlorination reaction step for converting silicon tetrachloride (STC) to trichlorosilane (TCS) is usually carried out in a fluidized bed reactor. However, the design and operation of industrial-scale fluidized bed reactor for the conversion of STC to TCS is currently based on ad hoc rules of thumb and operator experienc rather than on reaction engineering principles. In this paper, a fluidized bed model is developed by using the Kunii-Levenspiel fluidization framework. The predictive capabilities of this model are first tested on laboratory-scale experimental data from the literature. It is shown that the modified Kunii-Levenspiel model accurately predicts the no catalyst addition and copper catalyst addition experiments of the hydrochlorination fluidized bed with an average deviation of less than 6%. By making a suitable adjustment to catalytically active iron content, the model prediction is in excellent agreement with experimental data with hydrochloric acid in the feed stream. The modified Kunii-Levenspiel model is well suited for use in scale-up calculations for an industrial reactor as all the parameters are physically reasonable and can be predicted for larger reactors. Several simulations are conducted to study the effect of model parameters on conversion. The predictive capabilities of the model are tested using experimental results from a pilot-scale fluidized bed reactor and it is shown that the numerical predictions are in excellent agreement with experiments.