Assessment of a Two-Stage Zeolite Dryer for Energy-Efficient Drying

Abstract

Multistage adsorption drying with zeolite is experimentally evaluated for a single- and a two-stage dryer. For a 1:1 ratio between air flows for drying and regeneration, the energy efficiency for a single-stage system 50–54% and for the two-stage system 63%. Calculations with a calibrated model show that the two-stage system achieves a 4:1 ratio between the air flows an efficiency of 85%, 12% above that of a single-stage system. A sensitivity analysis shows the influence of operational conditions on the energy efficiency. Options to realize multistage adsorption dryer systems and to control such systems as well as the economic aspects are discussed.

Keywords:

• Adsorption
• Drying
• Energy efficiency
• Regeneration
• Zeolite

ACKNOWLEDGEMENT

This work was supported by the staff training program (TPSDP) of the Chemical Engineering Department of Diponegoro University, Semarang, Indonesia. The experimental setup was funded by project NEOT01005, Energy Research Program EOS of the Dutch Ministry of Economics. The drying equipment was constructed by Ebbens Engineering. Zeolite Siliporite 4 Å as adsorbent was provided by CECA, Brenttag.

Notes

Piping is stainless steel with an internal diameter (ID) of 0.05 m. All units and pipes are insulated.

The ratio between air for drying and air flow for regeneration is 4:1; for the two-stage twin-column system a 45-min cycle has been applied.