Using the potential of energy losses in gas pressure reduction stations for producing power and fresh water

Abstract

Due to their different capacities, power and heat production possibility, distribution in high populated areas, city gas stations (CGS) are a good option to meet the energy for water desalination. This study is aimed at using the waste energy of the city gas stations for producing power and fresh water. Accordingly, the exhaust heat of CGS heater is employed in multi-effect desalination thermal vapor compression (MED-TVC) system and power is produced using the turboexpander. A comprehensive model is developed to evaluate the performance of three CGS with different capacities of 2.5, 5 and 11.5 based on energy-exergy-exergoeconomic analysis. In addition, the effective parameters like Thermal Vapor Compressor (TVC) inlet temperature and pressure and first effect outlet temperature are optimized by means of the multi-objective Pareto method. Since the operating conditions of the stations are different, eventually Results show that considering the drinking water production, cost, exergy efficiency and gain output ratio (GOR), MED-TVC system with two effects employed in 11.5 kg/s CGS is the optimal system. It is also found that the optimal TVC inlet temperature and pressure as well as the first effect outlet temperature are equal to 108 °C, 70 kPa and 81 °C, respectively.