Influence of Degree of Unsaturation on Combustion Efficiency and Flue Gas Emissions of Burning Five Refined Vegetable Oils in an Emulsion Burner

Abstract

This work presents experimental studies performed on a low-pressure auxiliary air fluid pulverization burner fueled with refined vegetable oils to research the impact of the fatty acid profile on combustion and regulated emissions. The vegetable oils used were coconut, palm, rapeseed, sunflower, and soya. First, the fatty acid profile and the degree of unsaturation of these vegetable oils were determined by high-resolution nuclear magnetic resonance spectroscopy. The physicochemical properties (density, kinematic viscosity, heating value, and elemental analysis) were also determined and correlated with the degree of unsaturation. It was found that the higher heating value of vegetable oils increases as the degree of unsaturation also increases. In this experimental study, the influence of varying fuel flow rate at three input air flows on combustion efficiency and flue gas emissions was investigated. The nitric oxide and carbon oxide emissions obtained in all the tests performed are well below the permitted minimum levels. Combustion efficiencies equal to or above 80% were achieved for soya, sunflower, and rapeseed oils. A comparison between the degree of unsaturation of the vegetable oils and some combustion parameters is also established. In most of the experiments carried out, it was found that carbon oxide emissions decrease and combustion efficiency increases as the degree of unsaturation of vegetable oils increases.