Co-Firing of Coal with Pine Needles in a 20kw Oxy-Fired Bubbling Fluidized Bed: Experimental Investigation

Abstract

Oxy-fired fluidized bed combustion is one of promising technique which serves a dual purpose i.e. benefits of fluidized bed combustion and oxygen firing technology. India, being a diversified country has a vast resource of biomass which includes agricultural waste, organic matter, forest waste etc. Pine needles (PN) a forest biomass are abundantly available in the hills of North India and its proper utilization will strengthen the economy as well as reduces the pollution. Co-firing with oxy-fired fluidized bed has potential for negative CO2 emission level for power generation. Co-firing at low percentages of the thermal power (typically below 5-10 %) avoids the characteristic operating problems of biomass combustion. The present work extensively investigate the temperature profile, flue gas emission and the performance of co-firing coal with pine needles under air-fired and oxy-fired condition in a 20kW bubbling fluidized bed (BFB) combustor. Five different ratios of coal and pine needles are considered for this study are 100%/0%, 75%/25%, 50%/50%, 25%/75% and 0%/100%. Combustion is observed under control and stable for the blend when pine needle share is in-between 25% to 50%. Maximum combustion efficiency of 97.05 % could be achieved with 75%coal/25%PN under oxy-fired condition. The measured percentage of NOx and other gases are found in permissible limit.