Drying of Woody Biomass for Bioenergy Using Packed Moving Bed Dryer: Mathematical Modeling and Optimization

Abstract

Woody biomass in the form of chips has been recognized as one of the most promising resources for future energy. The woody biomass in a fresh state has an initial moisture content of 100–150% (dry basis) and this has to be reduced to 5–20% depending on the conversion technology used. A packed moving bed dryer was used in commercial drying of the woody biomass. In this work, a mathematical model was developed and numerically solved to simulate the packed moving bed drying process. From the model, wood temperature, moisture content, air humidity, and temperature were predicted as a function of bed depth and along the belt length reflected by drying time. The model has been applied to improve dryer design and drying operation. The results show that optimized drying can be achieved by using a countercurrent reversed flow configuration; thus, lower air flow rate can be used to achieve the required drying.

Keywords:

• Drying optimization
• Modeling
• Packed moving bed dryer
• Woody biomass