Refinery Gas Analyzer - Separates C1 through nC6, C6+ Hydrocarbons and Inert Gases

Importance of the Topic

The rapid and precise analysis of refinery gas streams is essential for optimizing process control, ensuring product quality, and maximizing refinery profitability. Variability in gas composition demands a robust analytical solution capable of resolving light hydrocarbons, inert gases, sulfur compounds, and aromatics within a short timeframe.

Objectives and Study Overview

This application note presents the AC Analytical Controls Hi-Speed Refinery Gas Analyzer (RGA) system. The primary aims are to:

• Separate and quantify C1–nC6 hydrocarbons, C6+ fractions, inert gases (N₂, H₂, He, O₂, CO, CO₂), H₂S, and BTEX compounds.
• Achieve a full gas stream characterization in under five minutes (extended BTEX analysis under thirty minutes).
• Demonstrate system robustness, repeatability, and applicability to both gaseous and liquefied samples.

Methodology and Instrumentation

The Hi-Speed RGA employs three dedicated analytical channels:

• Hydrogen/Helium channel with thermal conductivity detection.
• Permanent gases and H₂S channel using a PLOT column and TCD.
• Hydrocarbon channel (C1–C6, C6+) with PLOT column and flame ionization detector (FID).

Key design features include an isolated left-side valve box for improved thermal control and leak-free operation, automated shut-off valves for sampling consistency, and optional liquid sampling or programmable 13X column for enhanced permanent gas separation.

Instrumentation

• AC Hi-Speed Refinery Gas Analyzer system on 120/230 V Agilent 8890 GC platform.
• ACCURA temperature- and pressure-controlled vaporizing sampling device.
• Optional programmable 13X column and liquid sampling valve.
• GASXLNC™ software for automated property calculations and multi-level calibration.

Main Results and Discussion

The system delivers complete gas composition reports within five minutes for standard refinery streams and under thirty minutes in extended BTEX mode. Repeatability typically exhibits relative peak area RSDs below 0.5%. The linear dynamic range spans trace levels (<0.01 mol% for hydrocarbons, <0.02 mol% for inert gases, <0.1 mol% for H₂S) up to 100 mol%. High sample pressure capability (up to 375 psi) accommodates a wide array of feed streams.

Benefits and Practical Applications

The Hi-Speed RGA system offers:

• Rapid throughput to support on-line process monitoring.
• High accuracy and precision via uncompromised sample integrity.
• Flexibility for gas and liquefied sample analysis.
• Compliance with multiple standard methods (ASTM, EN, IP, UOP, DIN).

This capability enables refiners to maintain tight product specifications, quickly detect process upsets, and optimize energy efficiency.

Future Trends and Applications

Emerging directions include integration of high-speed GC data with real-time process control systems, incorporation of multi-dimensional GC techniques for enhanced speciation, application of machine-learning algorithms for predictive analytics, and remote monitoring via cloud-based platforms.

Conclusion

The AC Hi-Speed RGA represents a robust, cost-effective solution for fast and comprehensive refinery gas analysis. Its modular design, automated sampling, and advanced software support reliable operation across diverse applications, improving plant efficiency and product quality.

Reference

Standard methods: ASTM D1946, D7833, D2598, D3588, ASTM D2163; EN ISO 7941, EN 15984; IP 405; DIN 51666; UOP 539.