Packed bed

Packed beds may also contain catalyst particles or adsorbents such as zeolite pellets, granular activated carbon, etc.

The purpose of a packed bed is typically to improve contact between two phases in a chemical or similar process.

Packing offers the advantage of a lower pressure drop across the column (when compared to plates or trays), which is beneficial while operating under vacuum.

The number of theoretical stages required to make a given separation is calculated using a specific vapor to liquid ratio.

Disadvantages include the presence of thermal gradients throughout the bed, poor temperature control, and difficult servicing of the reactor.

Experiments are currently underway aboard the International Space Station to collect data and develop reliable models for in-orbit packed-bed reactors.

Tomographic techniques such as near-infrared, x-ray, gamma ray, electrical capacitance, electrical resistance tomography are used to quantify liquid distribution patterns in packed columns; choice of tomographic technique depends on the primary measurement of interest, randomness of packing, safety requirements, desired data acquisition rate, and budget.