Evaluation of three-column distillation system for ternary separation

A three-column arrangement of ternary distillation system having liquid composition profiles similar to residue curves is investigated here. The system is expected to have as high column efficiency as a fully thermally coupled distillation column (FTCDC) and improved operability. The performance of the system is examined with energy consumption by comparing with a conventional two-column system and the FTCDC. Two practical processes are utilized for the performance evaluation. From the comparison of energy requirement, it is found that the three-column system has high column efficiency for BTX process but not for gas concentration process. The collinearity requirement among the compositions of feed and products of the prefractionator in the three-column system leads to large mixing in feed tray raising energy consumption for the latter process.