Rice husk co-firing with coal in a short-combustion-chamber fluidized-bed combustor (SFBC)

This study encompassed the characteristics and performance of co-firing rice husk, a by-product of rice-milling process, with coal in a short-combustion-chamber fluidized-bed combustor (SFBC). Bed phenomena investigated in a cold-flow model combustor showed that with the different mixes of materials, the anticipated offshoot of combustion, the minimum fluidizing velocity (Umf) was 0.4–0.8 m/s. In concord with axial temperature profiles, axial gas concentration profiles implied that a recirculating ring was able to circumscribe CO within the short-main chamber. The formation, decomposition, and eventual maturity of NOx characterized the NOx evolution, inferred from concentration profiles. The impacts of fluidizing velocity and blending ratio on gas emissions and combustion efficiency (Ec) are described. The fluidizing velocity had consequential effect on gas emissions, except NOx. Surprisingly, NOx did not hinge much on increased N-content of the mixtures with coal. As expected, increased SO2 was relevant to increased coal mass. Increased fluidizing velocity adversely affected Ec while increased coal fraction enhanced Ec, mostly >97%.