Improving Accuracy and Precision in Crude Oil Boiling Point Distribution Analysis

Significance of Topic

Understanding the boiling point distribution of crude oil is essential for refining decisions, value assessment, and optimizing yields of key products such as gasoline, kerosene, diesel, and jet fuel.

Aims and Study Overview

This study evaluates the accuracy and precision of High Temperature Simulated Distillation (High Temp SIMDIS) for crude oil boiling point distribution and demonstrates the enhanced light-end analysis achieved by merging SIMDIS with a DHA Front-End (DHA-FE) technique.

Methodology

• High Temp SIMDIS (ASTM D7169): separates hydrocarbons from C5 to C100 using a temperature-programmed GC method with PTV inlet and calibration with n-alkanes.
• DHA Front-End (ASTM D7900): employs a pre-fractionator to isolate C1–C9 light components, analyzed on a long capillary column with FID for individual identification and quantification.
• Calibration and validation: baseline compensation, boiling point calibration with known n-alkane mixtures, reference oil validation, and detector response checks with gravimetric blends.
• Data merging: combining SIMDIS and DHA-FE distributions in specialized software to generate a corrected boiling point curve.

Instrumentation

• Gas chromatograph configured for SIMDIS mode with packed or capillary columns
• Programmable Temperature Vaporizer (PTV) inlet
• Pre-fractionator module for DHA Front-End
• 50 m capillary column for light-end separation
• Flame Ionization Detector (FID)

Main Results and Discussion

The High Temp SIMDIS analysis alone indicated an initial boiling point (IBP) of 36 °C and a recovery of 96.3%, with limited precision in the light-end region due to CS2 quenching. The merged SIMDIS/DHA-FE approach corrected the IBP to –0.5 °C and revealed that approximately 22 % of the crude volume elutes below C9—equivalent to about 44 000 barrels per day in a 200 000 bpd refinery. Detailed DHA-FE data further quantifies individual light hydrocarbons (e.g., methane, propane, n-butane, and pentane).

Benefits and Practical Applications

• Improved accuracy in light-end distribution enhances economic valuation of crude feeds.
• Enhanced decision-making for optimal product yield during refining.
• Automation and robust performance with minimal operator input.
• Applicability in refineries, independent testing labs, transportation companies, and pipelines.

Future Trends and Potential Applications

Ongoing developments may include integration with advanced detectors, extended boiling range calibration standards, and coupling with predictive modeling for real-time process control. Expansion of DHA-based front-end techniques promises even finer speciation of volatile fractions and compatibility with alternative solvent systems to minimize quenching effects.

Conclusion

Merging High Temp SIMDIS with DHA Front-End significantly enhances the precision of crude oil boiling point analyses, particularly in the light fraction. This combined approach offers critical insights for maximizing yields and refining efficiency, making it a valuable tool for the petroleum industry.

References

• Coto B., Coutinho J. A. P., Martos C., Robustillo M. D., Espada J. J., Peña J. L. Assessment and improvement of n-Paraffin distribution obtained by HTGC to predict accurately crude oil cold properties. Energy Fuels 2011;25(3):1153–60.
• Kaal E., Janssen H. G. Extending the molecular application range of gas chromatography. J Chromatogr A 2008;1184(1–2):43–60.
• American Society for Testing and Materials. Standard Test Method for Boiling Point Distribution of Samples with Residues such as Crude Oils and Atmospheric and Vacuum Residues by High Temperature Gas Chromatography. ASTM D7169-11.
• American Society for Testing and Materials. Standard Test Method for Determination of Light Hydrocarbons in Stabilized Crude Oils by Gas Chromatography. ASTM D7900-13.
• Wen Ping, Dai Lei. Analysis of effective factors on distillation range determination of crude oil and residuum by simulated distillation gas chromatography. Petrochem Technol Appl 2009;2009-04.