Co-firing of sugar cane bagasse with rice husk in a conical fluidized-bed combustor

Abstract

This paper presents experimental results on co-firing of ‘as-received’ sugar cane bagasse and rice husk in a conical fluidized-bed combustor (FBC) using silica sand as the bed material. Axial temperature, O 2, CO 2, CO and NO concentration profiles in the conical FBC operated at 82.5–82.8 kg/h fuel feed rate and various values of excess air (of about 40, 60, 80 and 100%) for different rice husk energy fractions (of 0.60, 0.85 and 1.0) are discussed. The bed temperature, CO and NO emissions from the combustor, as well as the heat losses and combustion efficiency, are also provided for the above operating conditions. The axial temperature profiles in the conical FBC were almost independent of excess air but noticeably affected by the rice husk energy fraction. The CO emissions were found to reduce for higher values of excess air and rice husk energy fractions. Meanwhile, the NO concentrations at all the points over the combustor volume and, accordingly, NO emissions from the reactor increased with higher excess air and energy contributions by rice husk. The co-firing of these fuels in the conical FBC at the rice husk energy fractions greater than 0.6 resulted in the sustainable combustion, with 95–96% combustion efficiency, and lower NO emissions compared with those for firing pure rice husk. Through co-firing with rice husk, an effective use of ‘as-received’ sugar cane bagasse becomes feasible for energy conversion in the fluidized-bed combustion systems.