Technology

Process Summary

Dow METEOR^™ technology is a single-step process in which Ethylene Glycol (EG) is directly produced from Ethylene Oxide (EO) by a thermal hydrolysis process. EO, for this process, is produced through the Dow’s EO-only process, referred to as the METEOR™ HEXTEO Process. The overall Monoethylene Glycol (MEG) yield in the ethylene glycols product is about 90 to 93%. The hallmark of the METEOR^® technology is that it is principally based on a simplified process structure involving fewer process steps, less major equipment, and smaller plot plan as compared to a conventional EG plant of the same capacity^[1].

Process Details

In the METEOR Process, an EO/water mixture is preheated and fed directly to an adiabatic reactor ①, which can operate with or without a catalyst. An excess of water is provided to achieve high selectivities to monoethylene glycol (MEG). Diethylene (DEG) and triethylene (TEG) glycols are produced as coproducts. In a catalyzed mode, higher selectivities to MEG can be obtained, thereby reducing DEG production to one-half that produced in the uncatalyzed mode. The reactor is specially designed to fully react all of the EO and to minimize back-mixing, which promotes enhanced selectivity to MEG.

Excess water from the reactor effluent is efficiently removed in a multi-effect evaporation system ②. The last-effect evaporator overhead produces low-pressure steam, which is a good low-level energy source for other chemical units or other parts of the EO/MEG process. The concentrated water/glycols stream from the evaporation system is fed to the water column ③ where the remaining water and light ends are stripped from the crude glycols. The water-free crude glycol stream is fed to the MEG refining column ④ where polyester-grade MEG, suitable for polyester fiber and PET production, is recovered. High-purity DEG is typically recovered via the addition of a single fractionation column. TEG exiting the base of the MEG refining column can be recovered as high purity products by subsequent fractionation.

References

1. S&P Global, Sep 2009, Ethylene Glycol, Process Economics Program Report 2I.
2. Jack, 5th June 2018, Ethylene Glycols Process by Union Carbide Corp, Oil & Gas Process Engineering.