BACKGROUNDThe following application concerns the removal of H2S from a water saturated CO₂ gas stream that was produced from an alkanolamine sweetener.

A natural gas plant located in the northwestern New Mexico, removes acid gas with alkanolamine absorption and regeneration. The resulting acid gas rejected in the regenerator vent contains over 99% CO₂ and as much as 150 ppm H2S. Reducing the H2S concentration to 10 ppm or less permits the gas to be discharged to the atmosphere.

SYSTEM DATA
  • Gas Flow Rate 5 MMScfd
  • Gas Composition 99 + %CO₂
  • Pressure 17-21 psig
  • Incoming H2S 150 ppm
  • Outgoing H2S 0-7 ppm
Enviro-Scrub® Consumption
  • 0.035 to 0.040 gallons per ppm H2S per million Scf. 2.11 to 2.41 lbs. sulfur per gallon of product.
SOLUTION
  • Specially formulated Triazine is injected via an atomizer into a horizontal line just ahead of a static mixer in the rich amine feed to the regenerator. Before the CO₂ reaches the contact tower, the H2S concentration drops from 150 ppm to 40 ppm. The remaining H2S is removed in the regenerator.
RESULTS
  • The contact tower is on liquid level control.
  • The 10 ppm permit H2S level is easily achieved and
    the air discharged into the atmosphere.
  • The spent Triazine is disposed of in permitted disposal wells.

This continuous system has produced substantial economic benefits for the customer.

TAKE-AWAYS:

  • H2S level reduced so that air can be discharged into atmosphere using Triazine.

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