Selexol

Selexol solvent is a mixture of dimethyl ethers of polyethylene glycols, nontoxic, with a high boiling point, and is an excellent solvent for acid gases. The selectivity for hydrogen sulfide (H₂S) is much higher than that for carbon dioxide (CO₂), so it can be used to selectively remove these different acid gases, minimizing CO₂ content in the H₂S stream sent to the sulfur recovery unit (SRU) with associated benefits on SRU sizing and economics, and enabling regeneration of solvent for CO₂ recovery by economical flashing. These points are reflected in Figure 1, which depicts a dual-stage Selexol process. The first column (sulfur absorber) removes most of the H₂S (and a limited amount of CO₂) from the feed syngas, which then flows to the second column (CO₂ absorber) which removes most of the CO₂. The rich solvent leaving the CO₂ absorption column is flashed in drums, from which relatively pure CO₂ is recovered. The solvent in the sulfur absorber column must be stripped in a column with reboiler to remove the high H₂S content gases.

Syngas Clean Up

• Commercial Technologies for Syngas Cleanup
• Syngas Contaminant Removal and Conditioning
  • Acid Gas Removal (AGR)
    • MDEA
    • Rectisol
    • Selexol
    • Sulfinol
  • Sulfur Recovery and Tail Gas Treating
  • Particulate Removal
  • Mercury/Toxics Emissions
  • COS Hydrolysis
  • Water Gas Shift & Hydrogen Production
• Developmental Syngas Cleanup Technology
• DOE Supported R&D Projects for Syngas Cleanup Technology
• Emissions Advantages of Gasification