High‐temperature Simulated Distillation Applications in Petroleum Characterization

Abstract

Abstract Simulated distillation (SimDist) is a gas chromatography (GC) technique which separates individual hydrocarbon components in the order of their boiling points, and is used to simulate the time‐consuming laboratory‐scale physical distillation procedure known as true boiling point (TBP) distillation. The separation is accomplished with a nonpolar chromatography column using a gas chromatograph equipped with an oven and injector that can be temperature programmed. A flame ionization detector (FID) is used for detection and measurement of the hydrocarbon analytes. The result of SimDist analysis provides a quantitative percent mass yield as a function of boiling point of the hydrocarbon components of the sample. The chromatographic elution times of the hydrocarbons are calibrated to the atmospheric equivalent boiling point (AEBP) of the paraffins reference material. The SimDist method ASTM (American Society for Testing and Materials) D2887 covers the boiling range 55–538 °C (100–1000 °F) which covers the n‐alkanes (n‐paraffins) of chain length about C 5 –C 44 . The high‐temperature simulated distillation (HTSD) method covers the boiling range 36–750 °C (97–1382 °F) which covers the n‐alkane range of about C 5 –C 120 . A key difference between ASTM D2887 and HTSD is the ability of the latter technique to handle residue‐containing samples (i.e. material boiling > 538 °C, 1000 °F). SimDist and laboratory‐scale physical distillation procedures are routinely used for determining boiling ranges of petroleum crude oils and refined products, which include crude oil bottoms and residue processing characterization. The boiling point with yield profile data of these materials are used in operational decisions made by refinery engineers to improve product yields and product quality. Data from SimDists are valuable for computer modeling of refining processes for improvements in design and process optimization. Precise yield correlations between HTSD and crude assay distillation (methods ASTM D2892 and D5236) have allowed HTSD to be successfully used in place of physical distillation procedures. This has given the refiner the ability to rapidly evaluate crude oils for selection of those with economic advantages and more favorable refining margins. SimDist methods are becoming more widely used in environmental applications. HTSD is useful for characterizing hydrocarbons which can be present as soil and water contaminants; for example, to map and follow hydrocarbon removal processes.