Investigation on a small-scale vertical tube evaporator multieffect desalination system: Modeling, analysis, and optimization

摘要

A growing population with depleting water resources has increased the requirement for desalination systems. Large-scale desalination plants have seen a growth in the recent period; however, the small-scale (SS) decentralized desalination plants' need has not been realized for the rural population. Low specific heat consumption for multieffect desalination systems makes it suitable for such decentralized operation. The challenge now lies in determining the system capacity and optimal operational range for the SS requirements. In this study, the thermoeconomic model for an SS multieffect desalination system for various configurations is developed. Optimization of the SS plant for the number of effects is performed to determine the optimal operational range of motive steam pressure, motive steam flow rate, and feed water flow rate. Total distillate production and freshwater cost are focused on objectives and constraints imposed over the input parameters with SS production. The results reveal that for a distillate production of 750 L/day, the motive steam flow requirement is estimated to be 25-35 kg/h with a pressure range of 2-5 bar. This study provided an overview for selecting the number of effects based on the commercial aspect of total production requirements.