Computation simulation of empty fruit bunch biomass combustion in a water-tube boiler

This study aims to reduce NOx emission by optimizing the secondary air system of the boiler using computational modeling and simulation. The shredded EFB is introduced in the inclined bed with primary air supply from the bottom of the bed. FLUENT Ver. 15.0 computational software is used to simulate the combustion of EFB in the grate-fired boiler and investigate the effect of four secondary air arrangements on the combustion characteristic and NOx emission level. The secondary air stream was optimized using an internal flue gas circulation system. Each case was compared to the initial setting. Results suggested that a tangential arrangement of the secondary air system promotes a better mixing rate and higher residence time, giving a lower combustion peak temperature of 1853 K which leads to a lower NOx emission of 257 ppm.