Experimental investigation on combustion and emission characteristics for heavy fuel and used motor oils blends in a free-flames burner

Abstract

The main objective of this experimental investigation is to evaluate the feasibility of heavy fuel (HFO) and used motor (UMO) oils blends combustion in a free-flames burner installed in an isothermal oven. Temperature and chemical products of the combustion process are reported for mass percentages blends from 25% to 100% UMO (UMO25, UMO50, UMO75, and UMO100). For these tests, a burner with preheated oil blends and a primary and secondary air injection system are considered. Firstly, pure heavy fuel oil (HFO100) combustion is tested on its thermal effect as a baseline, recording emission factors for gaseous and solid emissions. Then, fuel blends are tested using secondary air injection regulated for minimal CO emissions. Overall results show that: i) flames radiation heat transfer for fuel blends are higher than for HFO100, ii) combustion efficiencies increase in the range of 48.8% to 63.5% for UMO25 and UMO100, respectively, and iii) exergy balance with a preheated air combustion shows the highest value for UMO100. Finally, this study suggests that used motor oils as fuel have a potential application in free-flames combustion process.