Role of Hydrocarbon Building Blocks on Gas-to-Liquid Derived Synthetic Jet Fuel Characteristics

Abstract

The role of typical hydrocarbon building blocks of gas-to-liquid (GTL) derived jet fuels on their physical and chemical properties have been investigated. The ultimate goal of our studies is to develop accurate composition−property relationships for synthetic fuels to be used in optimizing synthetic fuel properties as per the aviation industry standards. The composition−property analysis has been carried out through formulating in-house fuel blends using neat GTL fuel building blocks (normal-, iso-, and cyclo-paraffins). Typical properties of interest in this study are density, freezing point, flash point, and heat content, all of which are essential for jet fuel certification. The systematic approach developed in this study was to identify an optimized region, in which all major properties for aviation standards are met. Different techniques were used, including the development of ternary mapping of these aforementioned building blocks alongside their physical properties. This has been achieved through formulating 35 blends giving a broad spread across the ternary map and generating a database from the experimental results. The optimized region and the composition−property relationships were obtained through building a statistical model of artificial neutral networks (ANNs) using the data generated as its basis. The generated data show that some properties, such as freezing point, exhibit nonlinear results whereas others are strongly linear, such as density and heat content. Aromatics in jet fuels are impactful (and required) even though their environmental harms are evident, and as such, their role on certain properties was preliminarily investigated. Furthermore it has been observed that different crystal shapes exist within some areas in the freezing point ternary map. Finally, the use of mathematical models as predictive tools was investigated, and in most instances the model developed was accurate. The outcome of the current study has been used to develop a new visualization technique for the relationship between GTL synthetic paraffinic kerosene's and their building blocks (i.e., paraffinic hydrocarbons).

Optimization of the Aromatic/Paraffinic Composition of Synthetic Jet Fuels

“…The data were estimated based on Eq. 2 and compared with experimental values obtained from a density meter as described by Elmalik et al 11. The trended data were found to be in excellent agreement with the experimental data as indicated by the R 2 value of ∼ 1.…”

“…As shown in the table, the extensive search for an appropriate freezing point model to predict the experimental data of our blends was not quite successful as well. This could be attributed to the nonlinearity in the freezing point behavior with the paraffinic building blocks as discussed by Elmalik et al 11.…”

“…The data were estimated based on this mathematical model and compared with experimental values obtained from a bomb calorimeter as explained by Elmalik et al 11. Fig.…”

“…The application of GTL technologies to monetize natural/shale gas and to facilitate transportation and utilization of the gas resources is an attractive strategy for countries with abundant gas reserves, such as the State of Qatar as highlighted by Ibrahim and Harrigan 10. Another advantage of GTL‐derived fuels is that they lack sulfur and aromatics, which makes them environmentally attractive 11. Qatar already has been regarded as the world's largest liquefied natural gas (LNG) producer, also has diversified its natural gas processing activities through constructing commercial‐scale GTL plants such as Sasol/Qatar Petroleum's Oryx GTL plant and Shell's Pearl GTL plant, the latter of which is the largest GTL plant in the world 12, 13.…”

“…1. In general, these properties in particular were selected as key properties for the study since they describe significant aspects related to smooth operability of jet engines and crucial safety mitigation measures described elsewhere 11.…”