Natural Gas Analysis by Gas Chromatography

Importance of the Topic

Natural gas and natural gas liquids represent complex matrices of hydrocarbons and trace constituents. Reliable compositional analysis is critical for process control, energy content determination, safety management, and regulatory compliance across the gas processing, refining, and distribution sectors.

Study Objectives and Overview

Wasson‐ECE Instrumentation outlines a series of tailored gas chromatograph configurations built around the Agilent 7890 GC platform. The goal is to address diverse analytical requirements in natural gas processing by combining multiple detectors and column configurations into unified workflows. Key configurations include:

• 326-00 Extended Analysis: Simultaneous TCD and FID/ capillary analysis of C1–C12 hydrocarbons with optional H₂S detection (GPA 2186/2286 compliant).
• 241-00 Sulfur and Hydrocarbon Profiling: TCD/FPD method for fixed gases, paraffins, and trace sulfurs (ASTM D6228 capable).
• 325-00 C1–C16 Extended Hydrocarbon Assay: Dual TCD/FID analysis to support accurate BTU calculations.
• 125-00 Fast Assay: Rapid TCD separation of C1–C6 saturates and initial C6+ backflush (GPA 2177/2261 compliant).
• 192-00 O₂/N₂ Separation: Packed‐column TCD method with optional H₂S analysis and C6+ backflush.

Methodology and Instrumentation

Analytical trains employ packed columns for bulk separation of permanent gases and lower hydrocarbons, and capillary columns for high‐resolution detection of C5+ species and aromatics. Detector combinations—Thermal Conductivity Detector (TCD), Flame Ionization Detector (FID), and Flame Photometric Detector (FPD)—enable simultaneous multi‐component quantification. An initial C6+ backflush prevents late‐eluting heavy fractions from interfering with early eluting analytes. Electronic pressure control and optional liquid sample valves support both gaseous and LPG sample matrices.

Key Results and Discussion

Run times vary from 18 minutes for focused sulfur assays up to 40 minutes for extended hydrocarbon profiles. Chromatograms demonstrate baseline resolution of CO₂, methane, ethane, propane, isomeric C4–C5 paraffins, C6+ backflush peaks, BTEX compounds, and sulfur species down to sub‐ppm levels. Dual‐detector configurations reduce total analysis time while preserving analytical precision and repeatability.

Benefits and Practical Applications of the Method

• Customizable GC modules assure fit‐for‐purpose analysis across a wide compositional range.
• Methods conform to industry standards (GPA 2177, 2186, 2261; ASTM D6228).
• High throughput supports real‐time process monitoring and quality assurance in gas plants and refineries.
• Robust method validation and on‐site support ensure data integrity and operational uptime.

Future Trends and Potential Applications

Emerging directions include coupling GC with mass spectrometry for detailed fractionation of heavy ends, development of portable GC units for field analysis, automated data processing via artificial intelligence, and expanded methods for renewable and unconventional gas streams.

Conclusion

Wasson‐ECE’s engineered GC solutions provide accurate, efficient, and flexible analysis of natural gas and related liquids. Configurable detector and column options, combined with expert application support, ensure reliable data generation and adaptability to evolving industry requirements.

Instrumentation Used

• Agilent 7890 Gas Chromatograph
• Thermal Conductivity Detector (TCD)
• Flame Ionization Detector (FID)
• Flame Photometric Detector (FPD)
• Packed and capillary chromatographic columns
• Electronic Pressure Control and liquid sample valves