Cenosphere Formation during Single-Droplet Combustion of Heavy Fuel Oil

Abstract

The current study aims to investigate cenosphere formation during single-droplet combustion of heavy fuel oil (HFO). A droplet generator was developed to produce freely falling monodisperse droplets uniformly. With the aid of high-speed imaging, droplet diameter was verified to be well controlled within the range of 390–698 μm, and droplets spacing distance was sufficient to avoid droplet–droplet interactions. Impacts of operation conditions (initial HFO droplet size, temperature, and air co-flow rate) and asphaltene content on cenosphere formation in a drop tube furnace were then investigated. Three types of cenosphere morphology were observed by field emission scanning electron microscopy (SEM), namely, larger hollow globules, medium porous cenospheres, and smaller cenospheres with a perfectly spherical and smooth structure. The SEM results show that the mean diameter of collected cenospheres increased as initial droplet size and asphaltene content increased, while it decreased as temperature and air co...