Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: Comparison of Vapor Recompression and Thermal Coupling for Energy Reduction in Binary Distillation
by M. A. Usman; T.O. Ajayi; and K.I. Famoriyo

Abstract:
This paper investigated two options to reducing energy consumption of distillation columns namely vapour recompression and thermal coupling (split tower). These methods are applied to an equimolal, saturated liquid feed mixture of methanol-water system. The system produces a saturated distillate product of 95 mol% methanol and a saturated liquid bottom of 5 mol% methanol. The energy requirements of the options investigated are computed and compared with that of a conventional single distillation column having the same system objectives. The results show that the conventional single distillation column consumes 2298.611kW, vapour recompression consumes 1528.106kW, saving 33.5% of the total energy requirement, while thermal coupling consumes 2039.927kW, saving 11.25% of the total energy requirement. The energy servings recorded are converted into monetary values and the economic analysis computed to determine the best economically viable option. The results show that vapour recompression is the best economically viable option amongst the options investigated and worthy of investment. The time length to recover the investments on the major equipment used for each option is also computed and this is based on the anticipated annual profit for four years of plant operation

Keywords: binary mixture; vapor recompression; thermal coupling; energy savings; payout time

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