OCR Text |
Show impaction of sufficiently large particles crossing the streamlines of the gas. Boiler operation using a 5.75:1 blend of middle to heavy distillate of SRC-II was investigated by Piper, et al. (1979). In general, for liquid fuel-fired boilers, carbonaceous emissions represented the largest contribution of particulates. When compared to No. 6 fuel oil, the emissions of the SRC-II blend were lower; furthermore, the particle size distributions on a mass basis were shifted toward smaller particles with the SRC-II fuel oil in comparison to the No. 6 fuel oil. Mean particles sizes, on the order of 0.04 to 0.06 ;jm, were generally equivalent for the No. 6 fuel oil at all loads and for SRC-II fuel oil at only half load. Only at full loads did SRC-II exhibit both small (0.05 pm) and larger (larger than 0.01 pm) agglomerated carbonaceous particles. Three coal-derived liquids were tested in a package boiler, modified to simulate a large utility boiler (Muzio and Aranad 1931). In staged combustion, the SRC-II middle distillate fuel produced finer atomization than No. 6 fuel oil; on the other hand, the SRC-II heavy distillate produced poorer atomization due to its higher viscosity. The morphology of the deposits observed indicated submicron diameter particles, with EDS and H-Coal combustions yielding particles whose diameters were less than 0.4 pm. Wash solvent from the SRC process was burned in a gas turbine combustor (Bauserman et al., 1979) and fine-grained particle deposits were observed. These investigators suggested that accretion of particles might have occured and resulted in large particles (2 ]im). However, the majority of the data from coal-derived liquids combustion 1.5.20 |