(149c) Enhancing Lubricity of Gas-to-Liquid (GTL) Paraffinic Kerosene Using Additives and Optimizing the FuelTMs Physicochemical Properties

The aviation industry is growing strong with an average growth rate of 6.2% over the last decade. It is estimated that the demand for jet fuel to be doubled by the year 2040, thus increasing the greenhouse gas (GHG) emission significantly by 2050 [1]. Synthetic paraffinic kerosene (SPK) which is a product of Gas to Liquid Technology (GTL) is an ultra-clean fuel since it has low aromatics content and negligible quantities of sulfur compounds. As the SPK is environmentally benign, it has a good potential to replace conventional fuel Jet A1; however, SPK suffers from lower lubricity compared to its conventional counterpart. Lubricity is a measure of the fuel’s ability to reduce friction and wear between the parts of the engine thereby making it a very important propriety for extending engine life. Currently, the industry is restricted to use a maximum of 50:50=SPK: JetA1 as mentioned in ASTM-7566 [2].

To improve the lubricity of a GTL kerosene three additives have been selected: linoleic acid, ethyl oleate, and quinoline. An optimization of the physicochemical properties concerning the additives concentrations has been conducted. Statistical regression method has been used to carry out the optimization for each physicochemical property. Each additive is blended with SPK at five different concentrations, and the lubricity of blends has been tested using test method D5001. Samples that meets the industry specifications (ASTM-1655/7566) for lubricity were further investigated to study the effect of the additive on density, flash point, freezing point, viscosity, and calorific value and later compare the results with pure SPK [3]. Every property has been determined experimentally following respective test method as mentioned in (ASTM-1655/7566) standards. Through this novel fuel blends have been identified that either meet or exceed the industry specifications for aviation fuel. Finally, the optimized fuel blends have been combusted in an internal combustion engine to study their emissions and compare it to pure SPK and conventional fuel.

The result of this study will help identify potential fuel additives for SPK that enhance the lubricity without compromising other critical physicochemical properties of a jet fuel. Additionally, a combustion study will help understanding impact of such fuel blends on the environment. This study will also attempt to find optimum SPK blends that have potential to be utilized, SPK in engines of commercial flights without further blending it with conventional fuel.

Reference:

[1] U.S. Energy, “ International Energy Outlook 2017 Overview,” Int. Energy Outlook, vol. IEO2017, no 2017, p. 143,2017.

[2] I A. Al-Nuaimi, M. Bohra, M. Selam, H.A. Choudhury, M. M. El-Halwagi, N.O.Elbashir, Optimization of the aromatic/paraffinic composition of synthetic jet fuels, Chem. Eng. Technol., Vol.39, p 2217, 2016

[3] E.E. Elmalik, B. Raza, S. Warrang, H. Ramadhan, E. Alborzi, N.O. Elbashir, Role of hydrocarbon building blocks on gas to liquid derived synthetic jet fuel characteristics, Ind. Eng. Chem., vol. 53, p 1856, 2014