The On-line Determination of Distillation Points of High Boiling Distillates by Process Gas Chromatography using ASTM D2887

摘要

Simulated distillation of the full range of ASTM D-2887 up to C44 carbon number can now be achieved by process gas chromatography (PGC). This means that samples having an end point up to 1013°F (545°C) can now be analyzed, online, meeting ASTM D-2887 criteria. Analysis of ASTM Reference Gas Oil gives excellent agreement with round-robin studies. Repeatability better than ± 1°F over 24 hours is attained over the boiling range with better than ± 2°F for the 0.5% Off point (or Initial Boiling Point -IBP) and 99.5% Off point (or Final Boiling Point-FBP). The simulated distillation analysis cycle time varies from 15 to 30 minutes depending on the sample and the percent off points of interest. The analysis utilizes well-known laboratory software for the chromatogram integration and recently developed software for Simulated Distillation (SimDis) calculation of the percent off points. The analytical hardware consists of a process gas chromatograph with an isothermal oven zone for the sample injection valve, a programmed temperature column compartment capable of ramping up to 330°C at 15°C/min. and a separately heated flame ionization detector. This configuration is suitable for Class 1, Division 1, Group C and D hazardous locations. The method uses a methyl silicone metal capillary column for robustness in the process environment where fused silica capillary columns have had a tendency to break. The method does not include a sample splitter which can lead to discrimination of peaks, but utilizes a liquid inject valve delivering a sample volume compatible with the capillary column used for the separation.