Flow in a Packed Column

Purpose

Single phase and two-phase flow in packed columns produces several phenomena important in process engineering. Commercial trickle bed reactors, for example, are on the order of 30 ft in height and 10 ft in diameter, A simpler apparatus available in the laboratory can be configured to serve a number of different objectives. It can be used to demonstrate the different flow patterns of two-phase flow in packed columns. It can as well offer means for studying the differing contributing factors to pressure drop in two-phase flow. The notion of dispersion of flow in random media can be illustrated and measured.

The parameters which may be varied are:

• gas flow rate, and
• water flow rate

The following phenomena can be studied:

• material properties, such as particle size and porosity
• effect of flow pattern on pressure drop, and
• effect of flow pattern on dispersion.

Experimental Set-up

The hardware consists of an acrylic cylinder, packed with glass spheres. A liquid can be circulated through the column and gas can be fed in co-current downflow. Two pressure transducers, mounted at two different axial locations, provide pressure information to a digital data acquisition system. These are used to measure pressure history during pulsing flow. A port for a conductivity probe and several tracer injection ports are available for dispersion tests.

Typical Experiments for the Packed Column

• Develop data correlations based on the Ergun equation to predict column pressure drop for air flow and two-phase flow.
• Dimenstein and Ng (Chem. Eng. Commun. 1986, 41, 215-235) modeled pulsing flow in a downflow trickle-bed reactor. Assess their correlations of pulsing effects on column pressures.
• Evaluate and correlate pressure drops for single- and two-phase flow when the liquid is a 0.25% (wt) solution of sodium carboxymethylcellulose in water, basing the correlation on theory to the extent possible. Obtain a quantitative correlation of the rheology.
• Evaluate and correlate pressure drops for single- and two-phase flow when the liquid is a 0.125% (wt) solution of sodium carboxymethylcellulose in water, basing the correlation on theory to the extent possible. Obtain a quantitative correlation of the rheology.

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