Predicting fluid‐bed reactor efficiency using adsorbing gas tracers

Gas tracers have been used frequently to predict conversion in chemical reactors. But in heterogeneous systems such as fluid‐bed reactors, tracer residence time data usually overpredict actual contact time and conversion. In this work, the general two‐phase countercurrent flow model is extended to include tracer adsorption, which is important in predicting contact time. The tracer used was SF6, whose adsorption on the solids could be varied over a wide range. The apparent reactor efficiency, calculated directly from tracer response, is shown to approach that estimated from the two‐phase model when the fluid bed approached homogeneity. This is the case for many large‐scale reactors that are operated in the turbulent fluidization regime. The use of horizontal baffles in methanol‐to‐gasoline cold flow models is shown to improve bed efficiency by staging the bed.