1. Chromatographic Analysis of
Natural Gas Liquids
Ben James
President, Petrochemical Services
Sherry Laboratories

2. Who is Sherry Laboratories
• Founded in 1947,
an industry leader
in independent,
third-party testing
• 10 laboratories
• Accredited testing
• Technical expertise
• Mission critical

3. Sherry Subsidiaries
Sherry Materials
Testing
Sherry Engineering
Group
Sherry Environmental
Testing
Sherry Petrochemical
Testing & Standards
Manufacturing
Sherry Microbiological
& Food Testing

4. Hydrocarbon Lab
• Serves industries such as:
– Natural Gas Production
– Gas Transmission Pipeline
– Drilling and Exploration
– Liquid Hydrocarbon
Fractionation
• Provides services such as:
– Gas Analysis
– Liquid Analysis
– Condensate Analysis
– Sulfur and Mercaptans
– Extended Analysis
– Flash and Shrink Test

5. Reference Standards
• Serves industries such as:
– Natural Gas Production
– Gas Transmission Pipeline
– Drilling and Exploration
– Liquid Hydrocarbon
Fractionation
• Provides products such as:
– Natural Gas Blends
– GPA and Custody Transfer
Chromatographic Standards
– Petrochemical Mixtures
– Refinery Gas Mixtures
– On-line Chromatograph
Calibration Gas

6. Analytical Methods
• GPA 2177
– “Method for the Analysis of Demethanized Hydrocarbon
Liquid Mixtures Containing Nitrogen and Carbon Dioxide
by Gas Chromatography”
• GPA 2186
– “Method for the Extended Analysis of Hydrocarbon Liquid
Mixtures Containing Nitrogen and Carbon Dioxide by
Temperature Programmed Gas Chromatography”

7. Composite Sampler
• Sample Probe
– Center 1/3 of Pipe
– Not located in dead-end or recirculation area
• Tubing to Pump
– Small Enough to Ensure That a Fresh,
Representative Sample is at the Pump Suction
Prior to Each Stroke
– High Pressure, Low Temperature

8. Composite Sampler
• Sample Pump
– Flow Proportional
– Repeatable Volume
• Sample Accumulator
– Floating Piston Type
– Mixer
– Sufficient Back Pressure
– Choose Back Pressure Gas Carefully
– Never Fill More than 80%

9. Transport Cylinder

10. Transport Cylinder

11. Sampling
• Mix Well
• Adequate Purging
• Transfer under Pressure
• Check For Leaks
• 80% Maximum
• D.O.T Regulations

12. Typical Automatic
Sampling System

13. From the Pipeline
To the Chromatograph
• 500,000 barrels
• To 15,000 cc
• To 1/2 microliter
• Less than 1 part in
150,000,000,000,000
• Sample Must be
Representative of the
Product Pumped

14. Chromatograph Systems
• Sample injection system
• Pressure, Flow and Temperature Control
• Columns
• Detectors
• Integrator or Computer Systems
• Calibration
• Calculations

15. The Chromatograph

16. Sample Injection
• Pressurize Inert Gas Side of Sample Cylinder
• Mix Sample
• Connect Product Side to Sample System
• Shut Purge / Block Valve
• Admit Sample to System
• Purge Slowly and Sufficiently
• Block In
• Inject Sample

17. Sample Injection System
Purge/Block
Valve(s)
Inert Gas
Filter
To Chromatograph
Injector
Carrier Gas

18. Sample Injection System

19. Column

20. Packed Column

21. Capillary Column

22. Column
• Polar
• Non-Polar
• Temperature
• Flow
• Temperature Programming
• Combinations of Columns

23. Hexanes Plus
• Back Flush
• Pre Cut
• Temperature Programming

24. Back Flush

25. Pre Cut

26. Extended Analysis
• Hexanes Plus Fraction of Sample
– Over 100 components
• Physical Properties Depend on Mix of These
Components
• Average Molecular Weight
• Average Density

27. Temperature Program
Temperature

28. Detectors
• Thermal Conductivity
• Flame Ionization

29. Thermal Conductivity Detector
• Universal
• Wire Filament or Bead
• Conductivity of Gas Determines Temperature
of Detector Filament
• Linearity
• Sensitivity

30. Thermal Conductivity

31. Flame Ionization Detector
• More Sensitive Than
TCD Collector
• Higher Linear Range Electrical
Signal
• Not Sensitive to H2S or
Flame
Flame
CO2 Tip
• Flame May Be Column Air
Effluent Hydrogen
Objectionable

32. Detectors
FID
TCD

33. Integration or Computer
• Adequate separation
• Integration parameters
• Peak identification
• Calibration

34. Chromatogram

35. Calibration
• 80 Mole %
• 80,000 Counts from Integrator
• 80 / 80,000 = 0.001 Calibration Factor
• 79,000 Counts
• 79,000 x 0.001 = 79 Mole %

36. Evaluating Calibration Standard
• Run as an Unknown
• Outside Lab Verification
• Plot of Response Factors
• Control Charts
• GPA 2198

37. GPA 2177
• Chromatograph Repeatability and
Reproducibility Criteria
• Revision 01/07/08
• Natural Gas Liquids

38. Plot

39. Calculations
• Industry Standards for Calculations
• Industry Standards for Physical Constants
– Latest Versions

40. Summary
• Good Sample to Chromatograph
• Sample Injection
• Peak Separation
• Detector Response
• Integration
• Calibration
• Calculations

41. Contact Us
Request Info Online at
www.sherrylabs.com/requestinformation
337.232.3568
2129 West Willow Street, Scott, LA 70583
105 Dalton Street, Suite E, Shreveport, LA 71106