Having considered three cases according to the content of the light component, Li et al. concluded that: 1) if a low-pressurized column operated at atmospheric pressure and the pressure of a high-pressurized column the pressure is increased by 27.28%, it influences TAC to decrease by 23.87%, 2) also if low-pressurized column pressure increases only by 0.57%, the same pressure increase as in the first case for the high-pressurized column here invokes reduction of TAC by 34.19%. For a particular case examined, it seems that if the pressure gap is reduced by less than 1%, TAC is, however, reduced by more than 10%. Even with classical control techniques applied, the results of Li et al. , and Wang et al. , are noteworthy. It is to note that, after having combined a system of double column stripper batch with a continuous rectifier, Li et al. proved a minimum pressure gap of 4.4. atm and succeed in impure alcohol products to their maximum. On the other side, having low/high-pressurized column pressure increase by 39.50%/75%, respectively, Wang et al. gained 12.11% /19.93% in TAC reduction. Compared with the improvement in terms of greenhouse gas emissions, where, high-pressurized columns saved almost 10% more. Most recently, for a minimum-boiling azeotrope of THF-water, Luyben , in a double continuous mode rectifier with vapor recompression, delimited LP/HP working pressure conditions to a vacuum of (0.6 atm)/above technical (11.3bar): outperformed "traditionally researched scheme" (Luyben ), by 19.4% in TAC, whereas, 40.15% with heat integration. Afterwads, Luyben in particular, proved benefits from vacuum distilling: for a specified range of pressure within the technical limits, for an increase of [2-2.5] folds, the reduction in capital cost varies from 20.64%-21.22%. Furthermore, for a ternary mixture of MEG/DEG and water, the author concluded for derived increments on investment, going from higher to lower vacuum pressure, to rise if moving toward the higher decimal value.