exergy analysis and heat integration of distillation columns using thermal coupling method for separation of ternary mixture

Despite distillation's popularity in the industry, it is highly energy-intensive. heat integration is, therefore essential considering the recent energy crisis. this paper presents thermal coupling as an approach for separating the ternary mixture of n-pentane, n-hexane, and n-heptane. in this method, the first column supplies vapor to the second column while its reboiler is removed. the thermal coupling method is evaluated using two classical arrangements, direct and indirect with and without heat integration. simulation of separation processes is carried out using aspen hysys, and distillation columns are simulated using the rigorous solving method rather than the shortcut method. the simulation results are compared to those obtained using the shortcut method (minimum produced steam). furthermore, exergy analysis is used for assessing processes in addition to energy analysis. it has been demonstrated that direct sequence provides better results than indirect sequence. moreover, direct-thermal coupling is considered the most efficient process among the four investigated processes. it has been concluded that compared to the indirect process without heat integration, the direct-thermal coupling sequence can reduce energy consumption and exergy loss by 69% and 55%, respectively, as well as improve exergy efficiency by 9%.