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Ethylene Oxide

MOGAS valves are designed for the conditions of ethylene oxide production.

ethylene oxide explosion
Major explosion at chemical plant producing ethylene oxide

Ethylene oxide is produced by the vapor phase oxidation of ethylene. A majority of ethylene oxide is used to make antifreeze, solvents and detergents, and in the production of polyester and plastic bottles.

Ethylene oxide is highly explosive. With a boiling point of 51° F, it may be a gas or a liquid, depending on the temperature. As a colorless gas, it has a sweet odor, though odor is not a reliable guide to its presence.

Although there are two production processes (air and oxygen), both technologies are broadly similar and pose the same hazards. Ethylene oxide liquid or aqueous solution affect the skin and is toxic with long-term exposure. It is a carcinogenic to humans through inhalation and increases the risk of lymphoid and breast cancer.

MOGAS valves are designed for the conditions of ethylene oxide production. Trapped ethylene oxide in valve cavities is the key consideration because it can polymerize and render the valve inoperative, and create an undesirable pressure build-up due to a very high coefficient of thermal expansion. In this instance, the valve needs to be vented on the upstream side, and therefore, unidirectional. Heating of a closed or isolated system containing ethylene oxide can lead to gasket failures and line or equipment rupture. Discharged ethylene oxide from relief valves should be captured and returned to its appropriate process location, or disposed of appropriately.

Controlling fugitive emissions is also an important consideration in a valve's performance. Valves must also be fire-tested.

  Typical Operating Conditions:
  • Temperature: 50 – 500° F (10 – 260° C)
  • Pressure: 350 – 725 psig (24 – 50 bar g)
  • Highly explosive

Ethylene Oxide Process Flow Diagram
  1. Ethylene Feed
  2. Air or Pure Oxygen Feed
  3. Inhibitor (1,2-dichloroethane)
  4. Ethylene Oxide Reactor
  5. Ethylene Oxide Reactor Recirculation
  6. Ethylene Oxide Scrubber
  7. Ethylene Oxide Scrubber Recirculation
  8. Ethylene Oxide Purge Reactor Pump Loop
  9. Recirculation Gas
  10. Ethylene Oxide Purge Reactor
  11. Ethylene Oxide Purge Reactor Recirculation
  12. Ethylene Oxide Purge Scrubber
  13. Ethylene Oxide Purge Scrubber Recirculation
  14. CO2 Absorber
  15. CO2 Stripper
  16. Ethylene Oxide Stripper
  17. Ethylene Glycol
  18. Light Ends Stripper
  19. Light Ends
  20. Ethylene Oxide Distillation Tower
  21. Ethylene Oxide + Water
  22. Ethylene Oxide
  • Heat Exchanger (not shown)
  • General Ball Valves (not shown)
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