Energy Optimization of Heat Exchanger Network of a Nigerian based Naphtha Hydrotreating Unit using Pinch Analysis.

Abstract

The rewards for integrated energy system are eco-friendily environment, high economic profitability, reduction in excessive energy utilization; greener and cleaner technology. This paper employed one of the best acceptable global practices in the concept of energy integration, it adopted pinch technology as a tool to address some of the global problems. Also, this study applied pinch technology in designing heat exchanger network with a high degree of energy recovery and drastic minimization of total annual cost (TAC). Realistic process streams data were used as input in the NHU simulation in Aspen Plus environment to aid the extraction of necessary thermodynamic data. Using Aspen Pinch, Heat exchanger network (HEN) of the developed NHU plant was designed, followed by strict application of pinch analysis and its principles to the process plant. The minimum temperature approach was optimized to obtain the optimum ∆Tmin of 15℃ for the minimum total annualized cost. The final heat exchanger network designed, based on this optimum ∆Tmin, is also presented along with its composite curve, grand composite curve and total annualized cost. With analysis of the NHU plant, an improved heat exchanger network (HEN) was obtained. Nineteen heat exchangers were used to obtain a minimum annual capital cost (ACC) of $17,301.46/yr, annual operating cost (AOC) of $561,994.20/yr and total annualized cost (TAC) of $579,295.66/yr. Also, 240,4989kw energy (Emission) and $11543.94/yr were saved with 2113.6m2 heat exchanger area utilized.