Operability of the Modified Petlyuk Process for Separation of Benzene, Toluene, and p-Xylene Ternary Mixture

A modified Petlyuk process with a reboiler at the bottom of the prefractionator eliminates the need for a vapor interconnection between the main column and the prefractionator and thus improves operability. However, the effect of this configuration on the operability has not been clarified. The present study examined the operability of a modified Petlyuk process with a reboiler at the bottom of the prefractionator for the separation of benzene, toluene, and p-xylene ternary mixture. The effect of the bottom-out to feed ratio of the prefractionator on the separation characteristics of the modified Petlyuk process was evaluated for different feed flow rates. The operation range of the modified Petlyuk process was clarified by presenting the conditions satisfying the product specifications as a contour plot for the feed flow rate and the bottom-out to feed ratio of the prefractionator. The operability of the modified Petlyuk process was compared with that of the original Petlyuk process. Based on the obtained results, a dynamic simulation verified that the product specifications can be satisfied simply by adjusting the bottom-out to feed ratio of the prefractionator for a disturbance of the feed flow rate.