The Determination of True Boiling Point data in Light hydrocarbon streams by Ultra Fast DHA and Fugacity Film model Software modelling

Significance of the Topic

Distillation data are fundamental to refining operations, embedded in product specifications and regulatory frameworks. Precise boiling point information underpins product value optimization, process safety, and compliance across the petroleum industry.

Objectives and Study Overview

This study presents an ultra-fast high-speed DHA chromatography method combined with a fugacity-film modeling approach to generate true boiling point (TBP) curves for light hydrocarbon streams. The goal is to overcome limitations of ASTM D86, including long cycle times, large sample volume requirements, and manual operation.

Used Instrumentation

• Gas Chromatograph: Model 436-GC with S/SL inlet and FID detector
• S/SL Inlet: Electronic flow control, constant pressure mode at 260 °C, glass wool liner
• Column: WCOT, 10 m × 0.1 mm ID × 0.2 µm film
• Oven Temperature Program: 35 °C (0.65 min), ramp to 45 °C at 100 °C/min (0.75 min), ramp to 60 °C at 100 °C/min (0.75 min), final to 230 °C at 50 °C/min (0.5 min)
• Carrier Gas: Helium at ~50 psi constant pressure, adjusted t0 to 0.31 min
• Software: CompassCDS for data acquisition, StillPeaks DHA-to-D86 modeling
• Autosampler: 8400 series, 0.2 µl neat injection to prevent overload

Main Results and Discussion

The method yields complete DHA chromatograms and derived TBP curves for naphtha, alkylate, and gasoline in approximately 6 minutes. Correlation with reference ASTM D86 data exceeded R² > 0.999 across all samples, demonstrating excellent accuracy. Repeatability studies on naphtha (n = 10) showed 2σ variability below 0.5 °C for most boiling points, increasing to ~1 °C near the final boiling point, indicating high precision.

Benefits and Practical Applications of the Method

• Rapid turnaround: ~6 minutes per analysis vs. >30 minutes for ASTM D86
• Minimal sample consumption: 2 ml compared to 100 ml
• Automated operation supporting up to 10× higher throughput
• Reduced fire hazard due to low sample volume and no open distillation
• Comparable or superior precision and accuracy relative to conventional methods
• Enhanced resolution of volatile fractions for detailed stream characterization

Future Trends and Opportunities

Further integration of ultra-fast DHA and fugacity-film modeling into routine quality control can accelerate regulatory acceptance and process monitoring. Prospective developments include expanding calibration libraries, coupling with machine learning for predictive analytics, miniaturized portable systems for field use, and comprehensive interlaboratory validation across diverse refinery streams.

Conclusion

The ultra-fast DHA method combined with fugacity-film TBP modeling offers a robust alternative to ASTM D86 for light hydrocarbon streams. It delivers true boiling point data with high accuracy and precision, drastically reduces analysis time and sample requirements, and enhances laboratory safety, presenting a compelling solution for modern refining and quality assurance environments.