Study On Process Simulating And Technology Developing For Ethanolamine Unit

Ethanolamines are commonly made by the method of reacting aqueous ammonia and ethylene oxide. Product profile, product quality and energy consumption are three key factors in ethanolamine process. Domestic product is weak in competition because of poor color quality and improper product profile, which are very common in domestic ethanolamine units. The poor color quality is caused primarily by the disadvantage in separating system, such as high pressure drop in distillation tower, high temperature at the bottom of the tower, and unsuitable choice of relative devices. By means of flowsheeting software PRO/â…¡, the process for ethanolamine unit was simulated in this paper, then some modification was made according to the feature of the process. The factors relating to devices in distillation system were also discussed to help solve the questions above-mentioned.As ethanolamines and their crude material ammonia and water are all polar components, the considerably accurate results can be obtained by using equation of state SRKM or liquid activity model NRTL in different units. On the basis of initial process, by recycling some of the monoethanolamine separated to the reaction system, the yield of diethanolamine and triethanolamine was increased greatly, which enhanced the flexibility of the unit, but more cost was needed for some new devices and the energy consumption was increased.Ethanolamine series are easy to be separated by distillation technology because of their high boiling point difference. According to this feature, an optimized distillation process with recycling streams and sidedraws was presented in this study. The simulating results showed that the temperature at the bottom of monoethanolamine tower and diethanolamine tower was reduced greatly, which helps to prevent the degradation of the solutions, so the color index can be lowered, at the same time the product purity was kept above 99% (by weight). As heat-sensitive material, ethanolamines have more critical requirement on the separating devices. Packed tower was suitable for the distillation, horizontal partial condenser was used as top condenser, and pumparound may also be used for triethanolamine tower, which helps to reduce the pressure drop; falling-film evaporator was used as reboiler, which eliminates the liquid static pressure and helps to reduce the residence time in high temperature region. The results of hydraulic rating showed that the pressure drop in the towers can be limited to a certain degree by choosing packing and distributor correctly, so the bottom temperature may not be too high, and the product quality can be ensured.Complete process pack for ethanolamine unit was obtained by this study.