喷雾蒸发-低温多效蒸馏集成海水淡化系统设计

To solve the problem of high-concentration brine pollution in the process of seawater desalination, a novel integrated low-temperature multi-effect distillation (LT-MED) system with spray evaporation is designed. A mathematical model for a five-effect parallel flow system with feed water of 1 kg/s is proposed. Based on the heat and scaling analysis, the system operation parameters are calculated under the condition with a steam extraction rate of 20%. In addition, a simplified non-equilibrium vaporization model is developed to describe the movement and evaporation behavior of a single water droplet in the dry air. A spray evaporation tank is designed based on the calculated results from the mathematical model. Finally, FLUENT is used to simulate the spray evaporation process, and the particle residence time and evaporation efficiency are analyzed. Simulation results indicate that this system should adopt steam extraction to avoid the occurrence of fouling in the last effect. The heat and mass transfer in the spray evaporation tank achieves a steady state after about 35 s and the evaporation efficiency is 82.2%, which can fulfill the original design intent. This system can effectively minimize the environmental impact resulting from the sea brine discharge.