Experimental Investigation of Lubricity Improvement of Gas-to-liquid (GTL) Fuels with Additives for Low Sulphur Diesel Fuel

In this study, lubricity improvers were added to three different GTL fuels, which were then quantified with a High Frequency Reciprocating Rig (HFRR) and compared with ultra low sulphur diesel fuel (ULS). Furthermore, the lubricity of mixtures of a GTL blended with ULS was also investigated. Two kinds of compounds were tested as lubricity improvers: unsaturated fatty acids (UFA-type) and partial UFA esters of glycerin (Ester-type). All GTL fuels showed less sensitivity to a lubricity additive than ULS did, but the ULS mixture had better than expected lubricity. Thus it was concluded that blending of GTLs with ULS can be regarded as one practical measure to sufficiently improve lubricity. HFRR tests performed under the same viscosity suggested that fuel composition had an important effect on its sensitivity to an additive, as well as viscosity.