BIOCHAR AND BIOSLURRY COMBUSTION

The combustion behavior of droplets of bioslurry formed by dispersing biochar in biodiesel 50/50 wt/wt is studied in a single droplet combustion cell. Combustion tests on biodiesel, used to form the slurry, were also carried out for comparison. A thermo-optical analysis, based on high speed imaging analysis coupled to the measure of the temperature of droplets, permitted to infer the main combustion features of the fuels. Bioslurry droplets undergo considerable swelling and expulsion of matter for a great part of their lifetime. The ignition of the droplets occurs at an ambient temperature in the range 640 670°C. A significant carbonaceous residue is observed on the thermocouple at the end of the homogeneous combustion of bioslurry droplets. It is burned in the following heterogeneous combustion phase. Typically, the heterogeneous oxidation last well longer than homogeneous combustion and is characterized by high reaction temperatures, around 1100°C. The resulting ash is rather compact and remains attached to the thermocouple.