Design And Experimental Study Of The Low Temperature Distillation Desalination System Driven By Afterheat Of Ships

The shortages of energy and fresh water are relatively serious for many special occasionssuch as islands, offshore platforms and ship, this problem often needs to be resolved bythemselves. While those occasions usually tend to rely on energy provided by dieselgenerators, but diesel generators will produce a lot of waste heat, which is taken away by gasabout25%and by cylinder liner cooling water about20%. The temperature of cooling waterranges from60to85℃, which belongs to low grade heat source. Research on how to makegood use of this low grade heat source for seawater desalination is an effective way to solvethe shortages of energy and fresh water.There are more than twenty kinds of desalination technologies currently, thereintoreverse osmosis, multistage flash distillation and low temperature multi-effect distillation arethe global mainstream technologies. At present, the main desalination methods of ships aredistillation and reverse osmosis, thereinto low temperature multi-effect distillation and reverseosmosis membrane is the future direction. Due to high requirement for seawater andpermeable membrane and Low water production rate, the application of reverse osmosismembrane desalination is limited. While low temperature multi-effect distillation desalinationdevelops and grows rapidly because of so many advantages.This paper designs and researches on a low temperature single-effect distillationdesalination model driven by making use of cooling water afterheat from diesel generators onships. The main work is as follows:First, analyze and study in detail on the core components of desalination systemincluding a wire mesh demister, educator, liquid distributor and heat exchanger. Design theexperimental device, find the optimal structures and parameters through the performancetests.Second, set the mathematical model of evaporator and condenser and select the conditionto calculate. Design and check the pipe diameters according to calculation results.Third,research on thermodynamic properties of desalination device based on thecalculation results of the mathematical model,evaluate the performance of device, then turnon the designing of the core components.Fourth, confirm the procurement plan based on the theoretical calculation results topurchase spare parts and install, debug and test it after the desalination system is installedcompletely, study on the testing data and turn on the optimization for the components andsystem, further design perfectly. In the study, a low temperature single-effect distillation desalination device is designed.By optimizing the key components and circuit, and analyzing its thermodynamic properties,confirm pipeline diameter and the procurement plan, and then purchase spare parts and install,debug and test it after the desalination system is installed completely. At last seawaterconcentration ratio and water production rate of this integrated device are1.123and0.760,respectively. The device has many advantages, as follows: it is driven entirely by afterheatfrom diesel generator without utilizing other energy, which is environmental and economy.The evaporator and condenser are set in the same cavity. The educator is adopted, replacing ofthe vacuum pump and centrifugal pump. Thus the volume is decreased and investment costsare reduced. Production costs are very low, while its amount of producing freshwater is largeand prospect of development is broad. The device has novel structures and high return oninvestment, in addition it has high development and research value.