Page 196 - Elements of Chemical Reaction Engineering 3rd Edition

168 Isothermal Reactor Design Chap. 4

4.4.3 Spherical Packed-Bed Reactors

When small catalyst pellets are required, the pressure drop can be signif-
4
icant. In Exa~iiple -6 we saw that significant design flaws can result if pressure
drop is neglecced or if steps are not taken to minimize pressure drop. One type
of reactor that minimizes pressure drop and is also inexpensive to build is the
spherical reactor, shown in Figure 4-8. In this reactor, called an ultraformer,
dehydrogenation reactions such as
paraffin --+ aromatic t 3H2

are carried out.

Figure 4-8 Sphencal Ultraformer Reactor. (Courtesy of Amoco Petroleum
Products.) This reactor IS one in a series of SIX used by Amoco for reforming
petroleum naphtha. Photo by K. R Renicker, Sr.

Another advantage of spherical reactors js that they are the most eco-
nomical shape for high pressures. As a first approximation we will assume that
the fluid moves down through the reactor in plug Bow. Consequently, because