A relatively simple model with physically meaningful parameters has been de
veloped to describe pressure drop across the three-levels-of-porosity (TLP)
reactor. This reactor has a structured catalyst packing and is suitable fo
r countercurrent trickle flow. The model is based on gas flow through the t
ortuous channels between the packing elements. The shape of these channels
introduces three different contributions to pressure drop: frictional loss,
expansion and contraction losses and 'zigzag' loss. The model describes pr
essure drop across different packings, without liquid flow, with a maximum
error of 20%. The model parameters show a good agreement with values calcul
ated with literature correlations. Irrigation of the packings leads to an a
dditional pressure drop of ca. 2 Pa per catalyst layer, or ca. 60 Pa per me
ter catalyst bed. This can be explained by the presence of a thin liquid fi
lm, which reduces the cross-sectional area available for gas flow. The deve
loped model can help to reduce the experimental effort hitherto necessary t
o develop novel reactor packings. (C) 1999 Elsevier Science Ltd. All rights
reserved.