Design And Research Of Marine-used Integrated Plate-type Desalination Unit

In view of the large size of precious metal of existing ship seawater desalination device based on thermal desalination,an integrated plate-type desalination unit,using cooling water of diesel engine cylinder as heat source,was designed.The water production rate is 22t/d.The desalination experiment system and separator performance testing system were built to study the overall performance of desalination unit as well as the pressure drop and separation performance of plate-type separator.The pressure drop and separation performance of plate-type separator were also investigated by numerical simulation.Since small water particles cannot be removed efficiently by original separator,a novel kind of separator with groove was designed,the pressure drop and separation efficiency of which were also investigated considering different groove size.Conclusions were drawn from the study:(1)hot water temperature as well as sea water flow rate plays a significant role in fresh water production.The fresh water production increases with the increase of hot water temperature and sea water flow rate.(2)the pressure drop of plate separator is fairly small and has limited impact on vacuum.The first stage of the separator is responsible for the main separation task,the separation efficiency of which can reach more than 99%;(3)numerical simulation results show that the separation characteristics of different size droplets in the vapor-liquid separator are affected by steam density and steam flow rate.For the vapor-liquid separator designed in this paper,steam density has a great influence on the separation efficiency of liquids smaller than 3 ?m,while steam velocity exerts significant influence on the separation efficiency of liquids larger than 3 ?m.The diameter of most seawater liquids carried by steam at the outlet of the evaporator steam is at least 6 ?m;(4)for plate-type separator with groove,highest separation efficiency can be achieved when the groove is positioned at the middle of the vertical plate.Groove width has no effect on the performance of the separator,while groove depth shows greatest influence on that.For the separator with groove designed in this paper,novel separator with 3 stages can obtain higher separation efficiency than original separator with 5 stages when groove height equals 4.1mm and groove depth equals 1.8mm.Plate-type separator with groove can reduce the separation stages and thus decrease desalination unit volume.