Experimental Study on Oxy-Fuel Combustion and NO Emission in a Spouted-Fluidized Bed with under Bed Feeding

Abstract

The spouted-fluidized bed is modified from the classical fluidized bed device, which combines the features of spouted and fluidized beds. In the present work, the performance of oxy-fuel spouted-fluidized bed combustion with under bed feeding and its effect on NO emission were systematically investigated. The results revealed that it was feasible to use a spouted-fluidized bed combustor for oxy-fuel combustion with real flue gas recycling. The transition from air combustion to oxy-fuel combustion was smooth and the concentration of CO2 in the flue gas could be as high as 90% steadily (dry base). Increasing the reaction temperature exhibited a negative effect on NO emission. Compared with that under the shallow bed, the concentration of NO in the flue gas was lower under the deep bed condition. Besides, the utilization of crush particles was favorable for suppressing NO emission because of the promoted mixing between coal particles and solid bed materials. Furthermore, the addition of limestone was proven to undesirably increase the NO emission during oxy-fuel spouted-fluidized bed combustion.