Thermodynamic, economic and environmental impact studies on various distillation units integrated with gasification-based multi-generation system: Comparative study and optimization

Abstract

Abstract This research proposes four scenarios for a multi-generation system to produce power, pasteurized milk, biofuel and fresh water for the northern areas of Iran. In all scenarios, power, pasteurized milk and biofuel are produced by a similar arrangement of a supercritical CO2 (S–CO2) Brayton cycle, a biomass gasifier and a milk pasteurization unit while the portable water is produced by a brine recirculation multi-stage flash (BR-MSF) in scenario 1, by forward, backward and parallel feed schemes of multi-effect distillation (BF, FF and PF-MED) in scenarios 2, 3 and 4, respectively. A comparative study is conducted for the exergy, exergoeconomic and exergoenvironmental performances of all scenarios with various stages and effects using Engineering Equation Software (EES). The optimum performances of all scenarios are found by applying the fast and elitist non-dominated sorting genetic algorithm (NSGA-II) and using linear programming technique for multi-dimensional analysis of preference (LINMAP), technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon entropy decision makers. According to the results, the maximum distillate water with capacity of 400.6 m3/day is obtained for scenario 1 through Shannon entropy method. Moreover, scenario 4 gives the maximum exergy efficiency with a value of 44.16% using LINMAP method and scenario 2 with the lowest total cost and environmental impact (EI) rates of 77.15 $/h and 33.35 mPts/s, respectively obtained from TOPSIS method is the best layout from the economic and EI aspects.