Rapid Fuel Quality Surveillance through Chemometric Modeling of Near-Infrared Spectra

The use of liquid fuels necessitates methods to assess the quality and suitability of these fuels for their intended use. Traditionally, this is performed through a series of chemical and physical tests. However, in some operational situations, streamlined methods to reliably evaluate fuel quality would offer distinct advantages. The Naval Research Laboratory has been engaged in a research program to explore and develop rapid automated fuel quality surveillance technologies. Chemometric modeling methodologies have been investigated as a means to derive mathematical relationships between spectroscopic measurements and measured fuel specification properties. While this is not a novel approach, the consistency and close quality control of today's production fuels render them non-ideal as calibration sets for the construction of multivariate property prediction models, and thus can limit their precision. This paper describes a practical approach to identify and predict the properties of petroleum derived fuels, as well as blends with Fischer-Tropsch synthetic and biofuels. The performance of these property models is demonstrated in an example of a hardware implementation, that is, the Navy Fuel Property Monitor (NFPM). The NFPM will rapidly estimate a range of specification fuel properties of jet and Naval distillate fuels, from a single analysis by near-infrared (NIR) spectroscopy. This technology will form the basis for control, acquisition and data analysis instrumentation for shipboard and land-based use. A further implementation of this technology will be for in-line sensing applications to provide real-time fuel grade and specification property monitoring as the fuels are moved through supply pipelines.