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

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

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

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.

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.

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

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

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

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.

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.

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.

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

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.

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.

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

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

Measurement: Flame Photometric Detection (FPD) Sulfur compounds are burned in a hydrogen rich flame Activated Sulfur species emit light in the 320-460 nm region upon decay to the ground state.

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.

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

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

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.

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.

Total Sulfur in Gasoline

Total Sulfur in Diesel

0verlay of Total Sulfur Chromatograms

Linearity Plot: Butyl Sulfide in Iso-Octane

Total Sulfur in Gasoline

Total Sulfur in Diesel

Repeatability Test Runs: Gasoline Samples 50 100 150 200 250 300 350 400 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

PGC2007 Technology – ASTM Method ASTM D7041-04 , “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.