Fast NGA System without He/H2 Analysis Nexis GC-2030 FRGA-II2 GC-2014 FRGA-II2

Importance of the topic

Precise analysis of natural gas and related gaseous mixtures underpins energy billing, process control and safety assessment. Reliable compositional data enable accurate calculation of heating value, relative density and emissions profiling.

Objectives and Study Overview

This study presents a rapid gas chromatographic system for simultaneous quantification of permanent gases and hydrocarbons from C1 to C6+. The goal is to deliver full compositional profiles within a ten-minute cycle, meeting industry standards such as ASTM D1945, D3588 and GPA-2261.

Methodology and Instrumentation

A multi-valve configuration directs sample through packed and capillary columns. Three sample loops introduce the gas into a pre-column for back-flushing of C6+ as a single fraction. Subsequent valve switching routes C3–C5 hydrocarbons to an alumina capillary column with flame ionization detection (FID), while a P-N packed column separates light gases (air, CO, CH4) before transferring to an MS-5A packed column. A secondary valve shift directs CO2, C2 and H2S onto a P-Q column. Thermal conductivity detectors (TCD) monitor permanent gases. Chromatographic separation is completed in about ten minutes.

Used Instrumentation

• Shimadzu Nexis GC-2030 FRGA-II2 or GC-2014 FRGA-II2 system
• Five packed columns, one capillary column, five valves
• Two TCD detectors, one FID detector
• LabSolutions GC workstation with BTU and specific gravity calculation software

Main Results and Discussion

The method achieves detection limits down to 0.001 percent for key hydrocarbons and 0.01 percent for permanent gases, covering concentration ranges from trace levels to above fifty percent. Representative FID chromatograms demonstrate clear resolution of C3 isomers and C4 species, while TCD traces resolve O2, N2, CH4, CO, CO2, C2H2, C2H4, C2H6 and H2S. Repeatability tests show consistent retention times and peak areas, ensuring reliable quantitation for quality control.

Benefits and Practical Applications

• Rapid throughput suitable for routine QA/QC and production monitoring
• Comprehensive profiling of hydrocarbons and permanent gases in a single run
• Software-assisted calculation of calorific value and relative density
• Compliance with major industry test methods

Future Trends and Opportunities

Integration of real-time data analytics and remote operation will further streamline gas analysis workflows. Advances in micro-column technology and detector sensitivity may reduce cycle times and detection limits. Coupling with advanced process control systems offers potential for inline monitoring in gas processing plants.

Conclusion

The described GC system provides a robust and efficient solution for natural gas analysis, delivering rapid, accurate compositional data. Its modular configuration and software tools support diverse industrial applications from custody transfer to environmental monitoring.

References

ASTM D1945 Standard Test Method for Analysis of Natural Gas by Gas Chromatography
ASTM D3588 Standard Test Method for Total Sulfur in Light Hydrocarbons by Gas Chromatography
GPA 2261 Standard Practice for the Calculation of Heating Value, Relative Density, Compressibility and Viscosity of Gaseous Hydrocarbon Mixtures