Integrating Detailed Hydrocarbon Analysis Data with Simulated Distillation to Improve the Characterisation Of Crude Oils By Gas Chromatography - Heidi Grecsek, Terry Osenbach, Andy Tipler

Simulated distillation (SimDis) is one of the most important analyses done in petrochemical laboratories. Many refinery units are controlled based on the SimDis report. Therefore having an accurate SimDis GC (Gas Chromatography) analysis is critical for these laboratories.

The SimDis GC application utilises a non-polar column to separate analytes based on boiling point. Then special software matches the crude oil fractions in the chromatogram with boiling point information. There are multiple crude oil SimDis methods available, primarily differing based on the carbon range required.

One of the most widely used SimDis methods for crude oils is ASTM D7169. ASTM D7169 is a high temperature SimDis, for characterising crude oil up to nC100. A common issues associated with this method is the interference by carbon disulfide between nC5 and nC6 in the chromatogram. The large carbon disulfide peak hides peaks in this range and affects the accuracy of the mass recovery of the SimDis curve below nC6.

One approach to eliminate the effect of carbon disulfide on the SimDis curve is to use low boiling point data from DHA. DHA (Detailed Hydrocarbon Analysis) is another common petrochemical GC application. It can provide component details for the light hydrocarbons not captured with SimDis. This application report will present an improved DHA analysis to be combined with the SimDis. Significant improvements to the DHA analysis will be presented here: easy back flushing, fast set up, and a significantly faster run time. In addition to providing a variety of improvements the method presented here is also a solution to the carbon disulfide interference in the SimDis analysis. Finally a merging software will be used to combine DHA boiling point data with SimDis to replace the data up to nC9 in the SimDis
report producing a more accurate boiling point curve for crude oils.