Abstract:
During coal-based power generation, fuel oil is used to assist with ignition of pulverised
coal. Fuel oil passes through several pieces of equipment on its way to the burner section of the
boiler. In this article the focus is on the lubricity behaviour of three representative fuel oil types and
on the potential blocking of filters and nozzles caused by the presence of unwanted components in
these fuel oils. The high frequency reciprocating rig (HFRR) (ISO 12156-1) was used to determine the
lubricity of these fuel oils at different temperatures. Results indicate that the presence of asphaltenes
(components of heavy fuel oils with complex aromatic structures) changes the viscosities of fuel oils,
which, in turn affect their lubricity behaviour. Medium wax-blend fuel oil (MFO) containing high
molecular weight paraffins (wax), low concentrations of asphaltenes and solid particles caused less
friction and wear (with coefficient of friction (COF) values below 0.1) and good high temperature
performance. Crude-derived heavy fuel oil (HFO), containing high concentrations of asphaltenes and
solid particles caused very high coefficients of friction (COF peaks above 0.3) and severe abrasive
wear at high temperatures. Although the third fuel oil tested was a light cycle oil (LFO) and did not
contain any asphaltenes, results indicated a sensitivity to oxidation, increasing with temperature,
which can have an adverse effect on in situ performance.
