1. Low Level Measurements of Sulfur in Fuels
Process Gas Chromatography
PGC2007
Heat
R-S + R-H + Air (O2) SO2 + CO2 + H2O
1000oC

2. Past 25+ years of Regulation
Lead-free gasoline, early 1970’s
Low evaporation gasoline, 1989
Winter oxygenated gasoline, 1992
Diesel fuel with 85% less Sulfur, 1993
Reformulated Gasoline (RFG), 1995
California cleaner burning gasoline (CFG), 1996

3. Sulfur in Petroleum Products
Sulfur Levels in Crude are Increasing
Sulfur levels in Petroleum Products are Decreasing
Requirements for Total Sulfur Levels <30 ppm
Gasoline and Diesel
North America, Europe, and Asia
Laboratory test methods available to determine sulfur in petroleum products.
EPA Sulfur Allotments and Credit Schemes

4. ASTM Round-robin Low Sulfur Results
Round robin results were made public in June 02.
Results show poor capabilities for all the tested methods.
The UVF could not measure well enough below 5 ppm in Diesel to have the results included in the statistics.
In fact, none of the 4 methods tested did well below 2 ppm.
The ABB PGC2007 has demonstrated repeatability of 1 ppm when measuring 100 ppm and below, in both Gasoline and Diesel samples.

5. Process Analyzers
As Sulfur levels decrease the need for real-time data will increase.
Process Analyzer need to;
be located in the plant close to the sample point.
operate continuously and unattended.
operate in hazardous and variable environments.
meets Safety Regulations (NEC, CSA, CENELEC etc.)
communicates with the plant’s process control system
Suppliers need to supply technical support, service and training globally.

6. Process Analyzers: Gas Chromatograph
GC Technology for Sulfur Analysis has Developed
1997: Vista 2007
Gasoline: 0 – 500 ppm
Diesel: 0 – 1000 (2000) ppm
2002: PGC2007
Gasoline: 0 – 30 ppm
Diesel: 0 – 30 ppm

7. Process Analyzers: Gas Chromatograph
Injection  Oxidation  Separation  Measurement
Flow Control
Injection: Novel Sample Injection Method
Oxidation: Constant feed to the furnace
Separation: Elimination Interferences
Measurement: Optimized of Detection for Trace Sulfur

8. Flow Schematic for Total Sulfur in Fuels
EPC
Sample Sweep
Air Carrier
Capillary
Split vent
FPD
PMT
Furnace
LSV
Column

9. Flow Control: New Method
Allows flow through the sample valve to be controlled separately from the column.
Improves Sensitivity by optimization of hydrocarbon flow rates
Reduces Cross Interferences from variation in sample composition
Improves Response Time
Improves Stability over Time
Improves Detectability and linearity
Tolerates a wide variation in Sample Vapor Pressure
Eliminates
Mixing chamber that was used to reduce peak sample delivery rate.
Separator valve that was used to compensate for poor separation of CO2 and SO2.

10. Flow Control: Sweep Gas
Hydrogen or Helium
Pressure is regulated by a second EPC.
Flow is through a capillary tubing.
Vaporized sample is carried out at a controlled rate.
Sweep gas pressure is set several PSI above air carrier pressure.
Flow is determined by the pressure difference and the restriction of the capillary.
Pressure settings are determined during application engineering.

11. Flow Control: Rate
The flow rate through the valve is varied following injection time.
Starting with a low flow rate and increasing over time to minimize tailing.
The initial rate of sample feed to the oxidation furnace is reduced.
The later rate of sample feed to the oxidation furnace is increased.
Using Hydrogen or Helium as the valve sweep gas improves the vaporization of heavy samples.

12. Injection Method: Liquid Sample Valve
New One Piece Vaporizer Assembly
Improves Alignment.
Improves Seal Life.
New low tension load adjustments allow for months of operation without additional adjustments

13. Oxidation: Optimization
New Flow Control allows for optimization of the furnace.
Conditions are always favorable for quantitative oxidation of the sample to carbon dioxide, water and sulfur dioxide.
Constant flow of hydrocarbons to the furnace.
Sensitivity
Improved since there is no competition for oxygen among sample components in the sample.
Sulfur concentration will not a function of composition of the sample
Carbon “Sooting” in tubing and column is eliminated, stopping the degrading sensitivity and peak shape over time.

14. Oxidation: Splitter Splitter is now downstream of the furnace
More sample goes through the furnace:
Faster sample conditioning.
Better peak shape and faster stabilization following a change in sample concentration.
Higher sample flow through the Furnace reduces cooling time and should reduce the formation of SO3
Better control of split flow rate (cleaner)
Split flow rate is set with the flow controller in the split vent.

15. Oxidation Furnace
Furnace: Low moisture quartz for longer service and better conversion
Temperature Control: 1000C for better conversion.
Reliability: New wiring harness materials, assembly and location

16. Measurement: Improvements
Low Level Sensitivity and linearity are enhanced by Standard Addition of Sulfur.
Photomultiplier Tube (PMT) Thermoelectric cooled to reduce thermal noise (background signal resulting from heat or dark current).
Auto-ignition circuit with close coupling of burner chamber, PMT, and optical filter
Chromatographic separation of the CO2 from the Sulfur to eliminate Quenching

17. Measurement: Flame Photometric Detection (FPD)
Sulfur compounds are burned in a hydrogen rich flame
Activated Sulfur species emit light in the nm region upon decay to the ground state.

18. Measurement: Sulfur Addition
Flame Photometric Detector (FPD) response is proportional to the square of the sulfur concentration.
As the sulfur concentration decreases from 1000ppm to 1ppm the light output of the reaction decreases by a million.
Standard Addition of Sulfur improves Sensitivity
The sulfur concentration change from 100ppb to 101pbb generates is 201 times more light then an increase from 0 to 1 ppb.
Adding 100ppb of Sulfur makes the FPD detector 200 times more sensitive.

19. Measurement: Sulfur Addition Module
Provides constant sulfur background.
Forces baseline into more sensitive, linear region.
Improves low-end range.
Sulfur Addition Module

20. Measurement: Automatic Ignition
High voltage spark ignition in an H2--rich atmosphere
No flow adjustments required to light the flame.
No thermocouples.
Light tube
Close Coupling of flame and PMT with Light Tube
Light Tube is polished to reduce light losses.
Stainless Steel Surfaces are coated to minimize memory effects.
Ignitor

21. Measurement: Photomultiplier
Thermoelectrically Cooled Housing
Reduces thermal noise providing better signal-to-noise characteristics.
Reduces dark current (non-signal related output)
Improves long-term stability (drift) by reducing temperature fluctuations
Extends PMT life expectancy by reducing operating temperature.

22. Measurement: Separation
Carbon Dioxide quenches the sensitivity if the detector
When sulfur addition is used carbon dioxide shows as a negative peak because it quenches the detectors sensitivity.
Sulfur addition makes carbon dioxide visible as a negative peak.
Chromatograph is adjusted to prevent overlap of the carbon dioxide and sulfur dioxide peaks.

23. Total Sulfur in Gasoline

24. Total Sulfur in Diesel

25. 0verlay of Total Sulfur Chromatograms

26. Linearity Plot: Butyl Sulfide in Iso-Octane

27. Total Sulfur in Gasoline

28. Total Sulfur in Diesel

29. Repeatability Test Runs: Gasoline Samples50
100
150
200
250
300
350
400
8/8/96
15:00
8/09/96
3:00
8/9/96
8/10/96
8/11/96
8/12/96
8/13/96
Sulfur, ppm

30. PGC2007 Technology – ASTM Method
ASTM D , “Standard Test Method for Determination of Total Sulfur in Light Hydrocarbons, Motor Fuels, and Oils by Online Gas Chromatography with Flame Photmetric Detection
Only Process GC with an approved ASTM method
This new method provides industry the only on-line method with precision and bias data that is 2-5 times better than any other total sulfur measurement method.
This is the only method to date that meets the requirements for trace sulfur in diesel compliance measurements.
Specifically, this test method covers the determination of total sulfur in liquid hydrocarbons with a final boiling point less than 450°C by gas chromatography using a flame photometric detector.
This test method is applicable for total sulfur below 1 ppm up to levels greater than 100 ppm.