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Chromatographic Analysis of Natural Gas Liquids
Ben James
President, Petrochemical Services
Sherry Laboratories
Who is Sherry Laboratories
• Founded in 1947, an industry leader in independent, third-party testing
• 10 laboratories
• Accredited testing
• Technical expertise
• Mission critical
Sherry Environmental Testing
Sherry Petrochemical Testing & Standards
Manufacturing
Sherry Materials Testing
Sherry Engineering Group
Sherry Microbiological & Food Testing
Sherry Subsidiaries
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
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
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”
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
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%
Sampling
• Mix Well
• Adequate Purging
• Transfer under Pressure
• Check For Leaks
• 80% Maximum
• D.O.T Regulations
From the PipelineTo 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
Chromatograph Systems
• Sample injection system
• Pressure, Flow and Temperature Control
• Columns
• Detectors
• Integrator or Computer Systems
• Calibration
• Calculations
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
Extended Analysis
• Hexanes Plus Fraction of Sample
– Over 100 components
• Physical Properties Depend on Mix of These Components
• Average Molecular Weight
• Average Density
Thermal Conductivity Detector
• Universal
• Wire Filament or Bead
• Conductivity of Gas Determines Temperature of Detector Filament
• Linearity
• Sensitivity
Flame Ionization Detector
• More Sensitive Than TCD
• Higher Linear Range
• Not Sensitive to H2S or CO2
• Flame May Be Objectionable
Column
Effluent
Air
Hydrogen
Flame
Tip
Collector
Flame
Electrical
Signal
Integration or Computer
• Adequate separation
• Integration parameters
• Peak identification
• Calibration
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 %
Evaluating Calibration Standard
• Run as an Unknown
• Outside Lab Verification
• Plot of Response Factors
• Control Charts
• GPA 2198
GPA 2177
• Chromatograph Repeatability and Reproducibility Criteria
• Revision 01/07/08
• Natural Gas Liquids
Calculations
• Industry Standards for Calculations
• Industry Standards for Physical Constants
– Latest Versions
Summary
• Good Sample to Chromatograph
• Sample Injection
• Peak Separation
• Detector Response
• Integration
• Calibration
• Calculations
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