Shaukat Abbas & Hassan Zeb*

*Corresponding Aurthur  ( Hassanzeb.cct@pu.edu.pk)

Abstract

Coal is still the prominent fuel for the power generation and it is estimated that its share will significantly increase to generate electricity, particularly in developing countries. Emissions of SOx, NOx and particulate matter during coal combustion has become a challenging issue for the world, and reduction in emission of these pollutants is currently one of the core motives of the world. Different technologies and techniques are being used to control the emission of these pollutants. In this work combustion of coal blends under conventional as well as oxy-fuel atmosphere were tested to achieved the optimum blend ratio at whichmaximum reduction could be achieved. Pakistani coal (Duki and Thar coal) was tested in a drop tube  furnace. To investigate the emission trend of pollutant, different blend ratios (by weight) of Duki and Thar coal (2:8, 4:6, 6:4, 8:2) were tested under conventional and O 2 /CO 2 combustion atmosphere. Results of the study indicate that Duki coal generate more NOx, SOx, however, less particulate matter than Thar coal under both combustion conditions. NOx and SOx levels were high under oxy-fuel combustion for both Duki and Thar coal; this is because of the reduction in overall volume of flue gases under CO 2 condition due to the higher density of CO 2 than N 2 . The maximum NOx reduction 65% at blend ratio 2:8 was seen under air combustion condition. However, under oxy-fuel combustion this trend was changed, 78% reduction in NOx was achieved at blend ratio 8:2. SO 2 emission was increased at all blends under both combustion conditions. Thar coal generated more particulate matter (PM 10 and PM 2.5 ) as compared to Duki coal. Under oxy-fuel combustion 21% reduction in PM 10 and 26% reduction in PM 2.5 from combustion of Thar coal was seen, while only 4% and 7% reduction in PM 10 and PM 2.5 was seen from Duki coal under same combustion condition respectively. At blend ratio 2:8, 8% and 12% reductions were observed under O 2 /N 2 and O 2 /CO 2 combustion condition respectively. In the case of PM 2.5 , at blend ratio 2:8, 24% and 34% reductions were achieved under air and O 2 /CO 2 combustion atmosphere respectively.