Uniting forces: a sustainable trigeneration strategy for flue gas heat recovery

At the Pardis Petrochemical Complex, the flue gas produced as a byproduct of natural gas reforming functions as a high-temperature thermal energy source. This investigation formulates an integrated trigeneration system that employs this thermal energy source and undertakes a thorough thermodynamic assessment. The flue gas energy facilitates the Kalina cycle and absorption chiller via two heat exchangers, while the residual heat generated by the Kalina cycle is utilized for the production of freshwater via seawater desalination. The simulation of the system was executed utilizing Aspen HYSYS software. The results of the base case demonstrate the generation of 3318 kW of electrical energy, 1119 kW of cooling capacity, and 12,710 kg/h of freshwater. Moreover, the analysis discloses that the total exergy destruction, exergy efficiency, and energy efficiency of the process are quantified at 6844 kW, 33.04%, and 14.94%, respectively. A parametric analysis was performed to optimize the system. The sensitivity analysis suggests that at a working fluid temperature of 195 °C and a pressure of 4500 kPa within the Kalina section, exergy destruction is minimized, while the production of system entropy is augmented. Under these specific conditions, the energy and exergy efficiencies are enhanced to 17.39% and 35%, respectively, accompanied by a total reduction in exergy destruction of 2.92%.

Graphical abstract