Design and optimization of distillation column sequencing for NGL fractionation processes

Abstract

NGL fractionation is one of the most energy-intensive facilities in hydrocarbon processing plants playing an important role in the petrochemical supply chain. Innovative schemes for multicomponent distillation processes made the opportunity to attain more justifiable fractionation processes. The current study presents a systematic procedure to design and optimize both simple and complex distillation schemes based on the separation matrix approach and applies it to a NGL feedstock. A modular design approach is presented for the ultimate rigorous evaluation. The genetic algorithm with a hybrid objective function that minimizes the TAC and checks products specifications simultaneously carries out optimization. The results demonstrate the capability of complex distillation sequences in process improvements, reducing costs and saving energy in NGL fractionation plants resulting in reductions of up to 3.5% in annual operating costs, which is very significant bearing in mind the huge NGL fractionation scale of operation.