Simulation of an Industrial Plant for Supercritical CO_2 Fractionation of Omega-3 Fatty Acid Ethyl Esters from Fish Oil

摘要

In this work a multistage continuous fractionation process was simulated. The process was intended to fractionate with supercritical CO_2 a mixture of fatty acid ethyl esters (FAEEs) from trout oil, with the aim of obtaining a fraction rich in omega-3 FAEEs. The plant was simulated by means of a model on the purpose developed. In the model the mixture of FAEE was simplified as consisting on five ethyl esters (ethyl esters of C14, C16, C18, C20 and C22 fatty acids) representing the fish oil composition. The model, based on Peng-Robinson equation of state, was at first validated with literature data. The plant was fed with 60 kg/h of FAEEs from trout oil, i.e. the potential oil production of ASTRO, a trout processing company located in Trentino, Italy. The target of the process was obtaining a high molecular weight stream composed of 85% EPA and DHA ethyl esters. Several simulations were performed around the best operational conditions claimed in the literature (T=60°C, P=14,5 MPa) resulting, according to our simulation results, in a column of 20 theoretical plates. The pressure was varied in the range 13,5-15,5 MPa, the temperature in the range 52-70°C. Through a preliminary cost-analysis, accounting for the whole plant (with pumps, heat exchangers, condenser), the best operational conditions resulted T=52°C and P=14,5 MPa: even if in this case 40 theoretical plates were necessary, the CO_2 to feed ratio was minimal and the operational costs sensibly reduced.