Easy Elemental Analysis of Heavy Fuel Oils Using Wavelength Dispersive X-ray Fluorescence

Heavy fuel oils are blended products based on the residues from various refinery distillation and cracking processes. They are composed from the highest boiling-point distillate fractions and non-boiling residuum of refined crude oils, resulting in viscous liquid products with a characteristic odor and requiring heating for storage and combustion. Heavy fuel oils are used as fuel for industrial heaters, boilers and engines in industrial plants, marine applications and power stations1. Other terms commonly used to describe heavy fuel oils include residual fuel oil, bunker fuel oil, industrial fuel oil, marine fuel oil and black oil. In 2008, 54% of the
total global production of 530 million metric tons of heavy fuel oil was consumed in the marine fuel market to power the huge compression ignition engines of the world’s ocean-going ships2.

Natural contaminants found in crude oil, such as sulfur, vanadium, nickel and iron (S, V, Ni, Fe) are largely tied up in complex non-volatile asphaltene and porphyrin molecules. As a result, these elemental contaminants
remain and concentrate in the heaviest distillate fractions associated with heavy fuels. Refining process contaminants such as catalyst fines (Al, Si) also concentrate in these streams. In a high temperature, oxygen-rich combustion engine environment, the concentration and interaction of these variously abrasive and corrosive elemental contaminants can become virulent and highly damaging, reducing equipment service life by up to 80%3. Likewise, heavy fuel contamination from used oils including zinc, phosphorous and calcium additives (Zn, Ca, P) can affect oil viscosity and increase volatility, lowering fuel quality and causing safety and reliability problems such as ash fouling, slag and corrosion in engines. High asphaltene levels in particular make fuel oils unstable when stored and result in poor combustion.