PM from the combustion of heavy fuel oils

Abstract

This work presents an experimental study investigating the formation and oxidation of particulate matter from the combustion of heavy fuel oil, HFO, droplets. The study includes results from both a falling droplet in a drop tube furnace and a suspended droplet in a heated convective flow. The falling droplets in a heated coflow air with variable temperature path and velocity were combusted and the resulting particles, cenospheres, were collected. To characterize the microstructure of these particles, scanning electron microscopy (SEM), and energy dispersive X-Ray (EDX) analysis were used. The particles were found to have either a porous or a skeleton/membrane morphology. The percentage of particles of either type appears to be related to the thermal history, which was controlled by the heated co-flow velocity. In the suspended droplet experiments, by suspending the droplet on a thermocouple, the temperature inside the droplet was measured while simultaneously imaging the various burning phases. A number of specific phases were identified, from liquid to solid phase combustion are presented and discussed. The droplet ignition temperature was seen to be independent of the droplet size. However, the liquid phase ignition delay time and the droplet lifetime were directly proportional to the initial droplet diameter.

Influence of Asphaltene Concentration on the Combustion of a Heavy Fuel Oil Droplet

“…As a result of the higher content of asphaltene, for the HFO24 sample and at the end of the HTO region, nearly 97.5 wt% of the initial mass was lost, leaving a residual mass of 2.5 wt% at 700 o C. A value of nearly 0.1 wt% was found at the same temperature, for the HFO8 sample. The cenosphere size was found to be directly proportional to the initial asphaltene concentration 27 . Thus, we found the residual ash more abundant in the HFO24 sample than in the HFO8.…”

“…The ignition delay time, IDT, is the time required for the combustible mixture to form around the droplet plus the time necessary for the early stage chemical reactions to ignite the droplet. In our previous work 27 , we discussed the required conditions for HFO droplet autoignition to occur. The IDT could be divided into a heat-up time and an evaporation/mixing time.…”

Experimental Comparison of Diesel and Crude Rapeseed Oil Combustion in a Swirl Burner

“…This result is not answered by either the smaller SMD, shown in Tables 4 and 5, or the slightly slower evaporation of R [36]. Hence, this is a probable root cause of the crust formation on the larger droplets, already observed for HFO [34,35]. The emissions of BL-R, BL-D, and Q15-D cases, shown in Figure 9, are shown in Figure 11.…”

“…The evaporation of heavy fuels is still less known, since the outer surface of the droplet might solidify even for kerosene gel [33]. Significant crust formation was similarly observed for HFO [34], featuring pores on the surface [35] where the oil inside left the droplet when evaporated. To overcome this issue, atomization with steam [30] might help, substituting air with an H 2 O atmosphere in the vicinity of the fuel nozzle.…”

Investigation of Interactions in the Cenospheres- Electrolyte System

“…Ценосферы -это полые стеклокристаллические алюмосиликатные микросферы, которые образуются в составе золы уноса при сжигании углей на тепловых электростанциях [1,2]. Они обладают ценными технологическими свойствами -низкой плотностью, высокой механической прочностью, термостабильностью и низкой теплопроводностью.…”