(35c) Using Dimensional Analysis to Scale Fixed-Bed Adiabatic Reactors

The most common reactor in catalyzed chemical processes is the fixed-bed reactor. The chemical processing industry (CPI) prefers this reactor for catalyzed processes because it has a relatively light capital requirement, catalyst is readily located --- most of the time, and it is inexpensive to operate. The CPI generally operates fixed-bed reactors adiabatically.

Fixed-bed reactors are deceptively simple at first blush. However, they are not easy to scale, either up or down. Strictly speaking, fixed-bed reactors do not meet the requirements for geometric similarity; thus, they invalidate the model theory used for their design. Also, most fixed-bed reactor scaleups or scaledowns do not meet the requirement of dynamic similarity, which again invalidates the model theory used for their design.

This presentation discusses the Dimensional Analysis of fixed-bed reactors. Since Dimensional Analysis provides the foundation for Model Theory, we will be discussing the foundation for adiabatic fixed-bed reactor design.