Measurement of Selected Physical and Chemical Properties of Blends of Coaal-Based Jet fuel with Dodecane and Norpar-13
Open Access
- Author:
- Guiadem, Sidonie
- Graduate Program:
- Fuel Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Harold Harris Schobert, Thesis Advisor/Co-Advisor
Harold Harris Schobert, Thesis Advisor/Co-Advisor - Keywords:
- thermal stability
Jet fuel properties
coal liquefaction
fuel characterization - Abstract:
- The aim of this work was to investigate the impact of blending a coal-based fuel, JP-900, with two model paraffinic fuels, dodecane and Norpar-13, on jet fuel properties. The thermal stabilities of the feedstocks and the blends were tested in the oxidative and pyrolytic regimes using microautoclave or tubing bomb reactors. Some properties, such as density, net heat of combustion, smoke point, flash point, viscosity and freezing point were also evaluated. The coal-based fuel JP-900 was produced at Intertek-PARC in Harmarville, PA, by hydrotreating and hydrogenating a blend of RCO (refined chemical oil), and LCO (light cycle oil) at 1:1 ratio by weight. For a fuel to be utilized in a jet engine, the fuel has to be thermally stable and also meet all the American Society for Testing and Materials (ASTM) requirements. All the properties evaluated were done following an ASTM standard. The study has shown that JP-900 meets the specification requirement for flash point and freezing point. But, the problem associated with high cycloalkane content in JP-900 is high density and low hydrogen content. Due to the high content of cyclic compounds in the coal-based fuel, JP-900 was blended with two models paraffinic fuels dodecane and Norpar-13 to evaluate the properties of the blends. The results from this blending are that some properties, such as density, hydrogen content and net heat of combustion, were improved. But, for the freezing point the blending did not improve the properties, because the paraffinic fuels had very high freezing points. The boiling point distribution of the samples was also evaluated under the ASTM D 2887. Models proposed in the literature were also tested on some properties such as flash point, freezing point and smoke point. The correlation proposed by Wickey and Chittenden predicted the flash point of the JP-900/Norpar-13 blend with an average absolute error of 1.8oC and 1.5oC for the JP-900/dodecane mixture. For the viscosity, the model from Moharam et al. accurately predicted the kinematic viscosity of the feedstock and all the blends with an average absolute error of 0.35 cSt. Except for the coal-based fuel JP-900, the Cookson et al. model accurately predicts the freeze point temperatures of the blends and the paraffinic fuels, with an average absolute error, predicted versus observed, of 1.95oC for JP-900/Norpar-13 and 3.2ºC for the JP-900/dodecane blend. For the sooting tendency, the model from Cookson et al. predicted accurately the smoke point of the coal-based fuel and two blends B101 and B201 with an absolute error of 1mm. Chemical compositions and structures of coal-based jet fuel were determined by GC/MS, 13C NMR and 1H NMR analyses. Quantitative analysis by GC/MS was used to classify chemical composition into seven groups of compounds, while NMR analysis was used to identify the aliphatic and aromatic regions of interest in this work. The results from GC/MS and NMR characterization showed significant agreement in terms of presence or non-appearance of aromatics in the fuels. The thermal stressing of the coal-based and paraffinic fuels, along with their blends, was conducted in the oxidative and the pyrolytic regimes using a 25 mL microautoclave reactor. In the oxidative regime 5 mL of sample fuels was heated at 200oC in the presence of air. The pyrolytic stability was determined by heating 5 mL of sample at 450oC under 100 psig of ultra-high purity N2 for different periods of time. The results from these stressing showed that JP-900 was thermally stable at both temperatures, 200oC and at 450oC for a period of 4h. The extents of fuel degradation in terms of liquid depletion and gas formation in the pyrolytic regime were higher with the paraffinic fuels than with the coal-based fuel. In the oxidative regime the addition of paraffinic fuels to JP-900 did not show any significant difference in the results, but in the pyrolytic regime, blending dodecane or Norpar-13 into JP-900 decreased the thermal stability of the blends.