Design Calculation And Thermal Performance Analysis Of Multi-Effect Evaporation Desalination System

Nowadays,with the development of the exploration of ocean resources and the increasingly closed communication around the globe world,fresh water as the necessities of the oceangoing voyage and the offshore platform become more and more significant.However,neither the ships nor the platform themselves can carry enough fresh water to meet the need of the working and living.It is one of the efficient way when we figure out how to achieve the seawater desalination taking advantages of the power plant of the ships or the thermal devices of the offshore platform.In this thesis,a mathematical simulation model is developed based on a horizontal-tube falling film evaporator which could generate 120 tons of fresh water per day.This device takes the steam turbine’s second-stage exhaust of the marine nuclear power plant.During the process,the boiling point elevation(BPE)caused by the change of seawater’s concentration and the temperature losses due to the friction in the tube bundles,the demisters and vapor transmission lines are all considered.Meantime,the fresh water,generated by the first effect,recycled separately to the main condenser of the power plant just to avoid the residual radiation from the secondary circuit.The thermal performance of the apparatus under different working conditions can be analyzedby calculation.After completing the mathematical simulation model,we can use the relevant parameters according to the engineering practice,such asthe designed water production,the salinity,the concentration ratio,gained output ration(GOR),the number of effects,the temperature of the first and the last effects’ steam,the temperature of the inlet’s seawater and so on to work out every effect’s seawater’s boiling temperatures,the quantity of fresh water,the brine’s quantity of outlet,the brine’s density,etc.According to the device,we chose the suitable heat transfer coefficient formula.It can finally get the needed heatexchange area of every effectof the evaporator.Then one of the original parameters can be changed to observe the influence on the GOR.At last,the system’s performance analysis can be checked through the ways of calculating or plotting when the system is working under different load.Meantime,I complete the stereogram of the device using the ProE and these may have a certain significance for this project.