A novel model for evaporator structural design in the multi-effect evaporation plant

摘要

In this paper, a novel model called Evaporator Structural Design (ESD) model is introduced. The model not only predicts the three-dimensional distribution of heat transfer coefficient under different operation conditions but also guides the evaporator structural design. The results show that the heat transfer coefficient decreases with the decline of the spray density from 0.08 to 0.015 and with the increase of the tube length from 2 m to 10 m. The heat transfer coefficient exhibits higher values for the evaporation zone than the preheating zone, almost twice or more. Either in the preheating zone or in the evaporation zone, the heat transfer coefficient in different row positions have small differences. A forward-feed MEE (multi-effect evaporation) plant with 14 effects is calculated using the ESD model. Compared with the experimental data, the relative error of the accumulated vapor mass flow rate in each effect ranged between 1% and 8%, that of the evaporator area is about 7%. The ESD model is accurate and convenient in engineering design.