To produce ethylene glycols (MEG, DEG and TEG) from ethylene oxide (EO).
Purified EO or a water/EO mixture is combined with recycle water and heated to reaction conditions. In the tubular reactor (1), essentially all EO is thermally converted into mono-ethylene glycol (MEG), with di-ethylene glycol (DEG) and tri-ethylene glycol (TEG) as co-products in minor amounts. Excess water, required to achieve a high selectivity to MEG, is evaporated in a multi-stage evaporator (2, 3, 4). The last evaporator produces low-pressure steam that is used as a heating medium at various locations in the plant. The resulting crude glycols mixture is subsequently purified and fractionated in a series of vacuum columns (5, 6, 7, 8).
The selectivity to MEG can be influenced by adjusting the glycol reactor feed composition.
Most EG plants are integrated with EO plants. In such an integrated EO/EG facility, the steam system can be optimized to fully exploit the benefits of the high-selectivity catalyst applied in the EO plant. However, stand-alone EG plants have been designed and built.
The quality of glycols manufactured by this process ranks among the highest in the world. It consistently meets the most stringent specifications of polyester fiber and PET producers.
Licensor: Shell Global Solutions International B.V.