Simdis Course AC Analytical Controls January 2001

Simdis Course AC Analytical Controls January 2001

Simdis - Introduction l Distillation is the most widely used separation process in the petrol industry l Knowledge of the boiling range is essential for quality assurance regulatory compliance refinery process control physical property predictions

Simdis Vs. Physical Distillation l D 86, D 1160 generates an average boiling point of a mixture at a given point l D 2892, 15 theoretical plate, true boiling point l Time consuming, labor intensive, imprecise

Simdis Vs Physical Distallation l GC analysis simulates a “true boiling point” l Simdis provides TBP of the individual components in a mixture at a given point l Automated l Accurate results l Fast l Detection of contamination or entrainment

Simdis Theory l The technique of simulated distillation is based upon the assumption that individual components of a sample elute from a GC column in order of their boiling point.

Available Simdis Methods Final boiling point l ASTM 3710 l ASTM 2887 l 2887 extended l Ht 750 260 °C 538 °C 620 °C 750 °C

ASTM D 3710 l Gasoline, naphtha, kerosene l Final boiling point (FBP)<260°C l Packed or capillary column

ASTM D 2887 l Petroleum products l Final boiling point (FBP)<538°C l Packed or capillary column l Cryogenic option

ASTM D 2887 Extended l Petroleum products l Final boiling point (FBP)<620°C l Capillary column l Cryogenic option

Ht 750 l Crude's and crude fractions, petroleum products l Boiling range from 35°C-750°C l Capillary column l Cryogenic option

Requirements l non-polar stationery phase l linear temperature program l compensation of column bleeding

Hardware l Gas chromatograph l Programmable temperature vaporizer (PTV injector) l FID detector l Column

Typical Gas Chromatograph Mol-Sieve Traps Fixed Restrictors Injection Port Regulators Detector Flow Controller Electrometer PC Column Carrier Hydrogen Gas Air

PTV

Flame Ionization Detector Schematic FID Detector Assembly Air Inlet Capillary Column End-Position (1 -2 mm from Top of Jet) Jet H 2 Inlet + Make-Up Exit End of Column

Flame Ionization Detector CO 2 + CHO H 0 2 CHO+ CO 2 + CHO CO + CHO 2 H 0 2 H H H H CH 4 2 CH CH 2 2 H 4 4 H 4 H The FID is a destructive, mass sensing detector. Cations generated in the flame are counted and produce the detector signal. Analytes that have the greatest number of low oxidation state carbons produce the largest signal. 2 2 2 Column 2 2 Jet

System Startup l Electrical connections l Gas connections – carrier, FID l GC and auto sampler configuration l Installation of liner & column l Installation of septum and syringe l Check flows

Simdis Theory l. A n-paraffin standard is analyzed to determine retention times l The times relate to the n-paraffin boiling points l A boiling point calibration curve is created by the software

AC SIMDIS D 2887 Calibration AC SIMDIS Analyzers 19

Calibration Report AC SIMDIS Analyzers 20

Calibration Curve AC SIMDIS Analyzers 21

Boiling Point Curve AC SIMDIS Analyzers 22

Simdis Theory l Every analysis should be corrected for column bleeding l Analyze a blank in every sequence l The blank signal is automatically subtracted from every sample and reference signal

Simdis Theory l The net signal is used to determine boiling points l IBP at 0. 5 % of the total area l FBP at 99. 5 % of the total area l The total area lies between start and elution point l The start and end time are determined by elution algorithms

Simdis Theory l. A reference sample is analyzed to check system performance

AC SIMDIS D 2887 Reference AC SIMDIS Analyzers 26

AC SIMDIS D 2887 reference reports AC SIMDIS Analyzers 27

AC SIMDIS D 2887 Reference Reports AC SIMDIS Analyzers 28

Starting Analysis l Make & run a sequence l Calibration l Observe results l Reprocess if necessary

Non Fitting Blank Chromatogram: 100 200 70000 0 300 Boiling point (°C) 400 500 600 700 800 65000 60000 550000 45000 Signal 40000 35000 30000 25000 20000 IBP 5000 FBP 10000 End Time Start Time 15000 0 0 5 10 15 20 25 Retention time (min) 30 35 40 45

End Time Found Incorrectly Chromatogram: 200 300 Boiling point (°C) 400 500 600 700 800 2600 2400 2200 2000 1800 Signal 1600 1400 1200 1000 800 End Time 200 FBP 400 Start IBP Time 600 0 0 5 10 15 20 25 30 35 Retention time (min) 40 45 50 55