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160 3. Heterogeneous Processes and Reactor Analysis

w
,
and a single-phase flo the flow becomes homogeneous at a distance 4–5 times the bed
diameter from the bed inlet, whereas in the case of low ratios of bed-to-particle diameter
(typically lower than 15), the flow becomes nonhomogeneous at a distance of 3–6 bed
diameters from the bed inlet, een in the case of an adequate floution (Perry and v w distrib
Green, 1999). perforated pipe The basic types of liquid-phase distributors are the following:
distributors, slot-type distrib perforated plates, and screens and beds of solids. utors,
Design of perforated pipe distributors This type of distributor is perhaps the most suit-
able, especially for beds of small diameter and of simple design. In Figure 3.42, this type
of distributor is presented.
The design of this distributor is as follows. The approach is based on turbulent flow into
the distributor, and thus for Re D 2100 (based on the distributor diameter and the liquid
velocity at the inlet of the distributor). Furthermore, the diameters of the distributor openings
as well as the distance between them are considered to be uniform throughout its length.
Under these assumptions, the pressure drop across the distributor is (Perry and Green, 1999)
fL 4   u 2
p  D 3  2 K   2 i (3.338)

Figure 3.41 Liquid maldistribution in the entrance of the f ed bed. ix

feed
Figure 3.42 Perforated pipe distrib. utor