S02 08 OnLine Characterization of Ethylene Furnace Liquid Feedstock

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S-02 / 08On-Line Characterization of Ethylene
Furnace Liquid Feedstock

• Rod Spitler Andy Weber
• The Dow Chemical Company

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Summary of Discussion

• Analysis requirements
• Available analytical methods
• Description of on-line system
• Validation of on-line results
• Conclusions

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Analysis Requirements
Total analysis of naphtha
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Available Analytical Technology
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On-Line System
GC System Mounted in Climate Controlled Purged
Enclosure Class 1, Division 2, Group B,C,D
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Valve / Column Configuration

• Analysis Time 195 min
• Approximately 45 min. dedicated to bake-out
• n-C16 elutes at 130 min.
• New data acquired approximately every 3.5 hours
  (including oven cool down time)
• May be able to shorten bake-out time to decrease
  time between updates

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Liquid Injection Valve
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Sample Conditioning System
Sample Acquisition Steps 1. V1 energized, V3
open, V4 open samples flows to inj. valve
(2 mins.) 2. V1 de-energized, V3 open, V4
closed sample pressurized with He 3.
Sample Injected to GC 4. V1 de-energized, V3
closed, V4 open inj. valve purged with He
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Chromatogram 1
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Chromatogram 2
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Chromatogram 3
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Measurement Precision
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n-pentane and iso-pentaneLab vs. On-line
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PIONALab vs. On-Line
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Conclusions

• A modified laboratory GC has successfully been
  configured for on-line use
• Non continuous slipstream flow with He purge
• Minimizes opportunities for flammable liquid
  leaks
• Minimizes potential for injection valves
  exposure to particulates, corrosive agents or
  pressure/temperature extremes.
• Measurement precision of lt 1 RSD (1 std. dev.)
  was demonstrated
• Good agreement between on-line and lab analyses
  was achieved