Optimization of the recycle structure of multiple stages molecular distillation

LAORETANI, DANIELA S.; IRIBARREN, OSCAR A.

CHEMICAL ENGINEERING RESEARCH & DESIGN

INST CHEMICAL ENGINEERS

Lugar: Reino Unido; Año: 2018 vol. 130 p. 35 - 41

0263-8762

In cases when the separation achieved by one molecular distillation stage is not sharpenough, it is resorted to multiple stage schemes. This brings the issue of how to recyclethe intermediate streams to optimize the process. The present paper proposes to use thesource-sink assignment methodology to decide the recycle structure. The counter currentscheme is also taken into account because it is usually regarded as the design of choiceto recycle streams. The approach was applied to optimize the recycle structure of a twostages process for the separation of free fatty acids from soybean oil deodorizer distillate,to get a concentrate of tocopherols in the residual stream, within specification of acidity.The counter current scheme was also implemented. For this case study the optimal recyclestructure gets 10% more product with a profit 0.6% larger than the counter current scheme,even if it has larger operative and investment costs. So, in this particular case, the rewardfor using a rigorous methodology was not that significant. However, the approach proposedhere is systematic and necessarily leads to a structure with a performance greater than orequal to any other, because the superstructure explored includes all of them