Comparison of Energy Consumptions and Total Annual Costs Between Heat Integrated and Thermally Linked Distillation Sequences

C. G. Hernández-Gaona and S. Hernández

Abstract
This paper presents a comparative analysis of energy consumption and total annual cost for the separation of ternary mixtures of hydrocarbons for different feed compositions. The separation schemes considered include two conventional distillation sequences, two thermally coupled distillation schemes, and two distillation sequences with heat integration. The results regarding energy consumptions indicate that the distillation sequences with heat integration can reduce the energy demands between 20 and 40 % in contrast to the direct and indirect distillation sequences; furthermore, energy savings achieved in the thermally coupled distillation schemes are up to 30 % with respect to conventional schemes. When the total annual costs are compared, the thermally coupled distillation sequences can achieve savings 10 % higher that the heat integrated distillation sequences; that is because the heat integrated distillation sequences require higher operational pressures than the conventional and thermally coupled distillation sequences. Also, because of the levels of operational pressure used in the heat integrated distillation schemes, they require additional utilities with the corresponding cost increase.

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Keywords
distillation, energy integration, Thermally coupled distillation