Analysis of Refinery Gas

Significance of the Topic

The analysis of refinery gas mixtures is critical for monitoring process efficiency and product quality in petrochemical operations. Light hydrocarbons such as methane, ethylene and propylene are key feedstocks and byproducts; their precise quantification ensures optimal operational control and safety compliance.

Objectives and Study Overview

This study demonstrates a robust gas chromatography method for the separation and quantification of 21 light hydrocarbon components in refinery gas. The method employs a low polarity alumina PLOT column paired with flame ionization detection to achieve high resolution of C1 to C6 hydrocarbons and their isomers.

Methodology

The separation was performed on a 50 meter by 0.53 millimeter inner diameter alumina PLOT column with a 10 micrometer film thickness. The temperature program initiated at 45 °C, held for 1 minute, ramped at 10 °C per minute to 200 °C, and held for 3.5 minutes. A 10 microliter split injection was used with a split vent flow of 80 milliliters per minute. Hydrogen served as the carrier gas at constant pressure of 8 psi, providing a linear velocity of approximately 74 centimeters per second at the initial temperature.

Instrumentation Used

• Gas chromatograph with flame ionization detector operated at 200 °C
• SH-Alumina BOND/KCl PLOT column 50 m x 0.53 mm I D df 10 µm
• Hydrogen carrier gas at 8 psi constant pressure

Main Results and Discussion

The method achieved baseline separation of 21 hydrocarbons including methane, ethane, propane, propylene, various butenes, butanes, pentanes and hexanes. Isomeric compounds such as cis and trans butenes, isobutylene, and 1,3-butadiene were resolved with sharp peak shapes and reproducible retention times. The alumina PLOT column provided stable performance for light gases and demonstrated effective selectivity for low polarity analytes.

Benefits and Practical Applications

• Comprehensive profiling of refinery gas streams for quality control and process monitoring
• High resolution for isomer differentiation in complex mixtures
• Rapid analysis suitable for routine industrial laboratories
• Robust and reproducible method reducing downtime and maintenance

Future Trends and Potential Applications

Future developments may include coupling this PLOT column methodology with mass spectrometry for trace-level detection, integration with automated sampling systems for online monitoring, and adoption of microbore columns to reduce analysis time and carrier gas consumption. Machine learning algorithms could further enhance peak identification and quantitation in complex gas mixtures.

Conclusion

The described GC-FID method using a low polarity alumina PLOT column enables reliable and efficient analysis of refinery gas samples. Its high resolution, robustness and adaptability make it an ideal choice for petrochemical quality control and research laboratories.

References

Shimadzu Corporation ERAS-1000-0423 First Edition March 2023