Particulate Emissions From Residual Fuel Fired Boilers: Influence of Combustion Modification

Abstract

Studies were carried out in a residual fuel fired package boiler to assess the effect of various combustion modification procedures on the amount and size distribution of particulate emissions. It was found that application of moderate levels of either two stage combustion or flue gas recirculation did not have much effect on particulate loading. Severe staging as well as use of interstage heat transfer to cool the gases between stages produced significantly more particulate. Likewise, higher levels of flue gas recirculation produced substantially more particulate. In both techniques the change in size distribution was mainly in the >10- and 1–10-μm ranges. Emulsified oil containing up to 30 percent water reduced particulate loading primarily in the coarse size ranges. Satisfactory combustion could be obtained using a preheat temperature and excess air level below that required for the straight residual fuel oil.