Ethanolamines Production

The process under analysis comprises two major sections: (1) Reaction; and (2) Purification.

Reaction. Ammonia is mixed with water to form an aqueous ammonia solution (45 to 55 wt% of ammonia). Ammonia is supplied in excess to the reactor, so ethylene oxide is fully consumed in the reaction. Water also plays an important role accelerating the reaction. The reactions achieve yields from 98 - 99%. The balance is lost in minor side reactions that generate some heavy by-products, which need to be separated in the purification section. The final product composition depends exclusively on the molar excess of ammonia fed to the reactor. The reactor outlet comprises MEA, DEA and TEA, as well as unreacted ammonia dissolved in water and heavy by-products.

Ammonia recovery. The reaction product is fed to an ammonia stripping column for separating the excess ammonia present in the mixture. Ammonia/water vapors are recycled to the reaction, while the liquid bottom product is routed to a two-stage evaporator and then to a dehydration column, where residual ammonia and water are separated from ethanolamines and also recycled to the reaction area. Ethanolamines are withdrawn as the bottom product of the dehydration column and transferred to the purification section.

Purification. The ammonia-free ethanolamines are further separated in three purification columns. Small amounts of MEA and DEA may also be recycled to the reactor to balance the desired output of each ethanolamine - MEA/DEA/TEA ratios of 1/3 : 1/3 : 1/3. A small stream of heavy by-products waste is separated in the TEA purification step.