Staged Combustion of Rice Straw in a Fluidized Bed.

Document Type : Research Studies

Author

Associate Professor Department of Mechanical Engineering, Mansoura University, Egypt.

Abstract

Staged combustion of rice straw has been investigated using a fluidized bed combustor of 300 mm ID and 3300 mm height. With air staging, secondary air is fed higher up in the freeboard at 1500 mom above the distributor of primary air. Rice straw is fed as cylindrical pellets with 12 mm diameter and 10 mm length, The obtained results indicate that staged combustion is an effective way to reduce NOX emissions, in particular, at higher operating temperatures. NO, typically reduces by 50% when secondary air ratio becomes 30% at 850°C bed temperature. Staged operation has a slight, non-monotonic effect on SO2 emissions. Combustion efficiency increases with increasing secondary air ratio reaching a maximum value that is mainly attributed to a reduction in fixed carbon loss. However, combustion efficiency decreases after a maximum as a result of growing exhausted carbon monoxide and fixed carbon loss. The range of secondary air, over which combustion efficiency increases, widens at higher operating temperature.
 

Keywords

Main Subjects