Hydrodynamic multiplicity in a tubular reactor with solid foam packings

• Hydrodynamic parameters in solid foam packings were studied in tubular reactors at a wide operating range.
• Significant hydrodynamic multiplicity phenomena were observed in solid foams which are highly affected by the foam density.
• The pulse regime is indicated at high foam density. A new regime map was proposed.
• The hydrodynamic performance of solid foams is demonstrated by new correlations, which take multiplicity into account.

Catalytic active open foam packings are promising to enhance the performance of tubular reactors for gas–liquid–solid reactions. In this paper the hydrodynamics of gas–liquid two-phase flow through foam packings in co-current downflow mode of operation are studied experimentally. In particular, the effects of gas and liquid superficial velocities and the pre-wetting mode of the packing (‘LEVEC’ and ‘KAN-LIQUID’) on pressure drop, liquid holdup, and axial liquid dispersion were researched. The experiments revealed multiplicity behavior of the hydrodynamic phenomena in the packed bed. The multiplicity has a significant impact on the forming of upper and lower parameter branches of hydrodynamics. Taking the aforementioned phenomena into account, new correlations are proposed to predict the pressure drop and the total liquid holdup. The occurrence of different flow regimes depending on the foam pore density, namely trickle flow regime and pulse flow regime, was observed. The results can be applied for a better understanding of the heat and mass transfer and overall chemical conversion of tubular reactors with catalytic active foam packings.