FRESH WATER GENERATOR

• PRINCIPLE:It works on the principle that"when pressure of liquid decreases then boiling point of liquid also decreases. 

•COMPONENTS:

       1)Condensor

       2)Evaporator

       3)Brine ejector

       4)Air Ejector

       5)Distillate pump

       6)Salinometer 

       7)Demister

•MATERIALS:

         1)SHELL:  fabricated stell(non ferrous metal)with rubber coating

         2)TUBES:   Alluminium and brass

         3)CONDENSOR &PLATES:  Titanium

         4)DEMISTER:.   Nikel Monel Metal

• WORKING:

a)the brine ejector removes excess sea water&air ejector removes excess air from the shell. This leads to creation of vaccum inside the shell chamber. 

b)Creating vaccum inside the chamber leads to reduction in boiling point of sea water. Approx 90%vaccum in created inside the shell chamber. 

c)After creating vaccum inside the chamber the sea water is led in the evaporator and condensor chamber using sea water pump at a pressure of about 3 to 4 bar. 

d)The evaporator is connected with jacket water supply line whose inlet temperature is around 75 to 80°C. 

e)Due to vaccum condition inside the chamber the sea water boils off at 75 to 80°C(heat from jacket water). Boiling off of sea water leads to conversion of sea water to vapour form also called fresh distillate water vapour. 

f)This vapour then passes through Demister. The demister serves as the purpose of trapping any salt content and water vapour if travelled through vapour. 

g)This distillate vapour then passes through Condensor. The Condensor is also supplied by sea water. This leads to exchange of heat and the distillate vapour turns to distillate water amd is filtered in tray connected beneath Condensor. 

h)The collected water is pumped by distillate pump and passes through 3 way valve. One end of 3 way valve is connected to Salinometer,one end to hydrophore tank and remaining one end to sea water inlet line. 

i)If the Salinometer reading is 4 ppm or less then the water passes to fresh water storage and if it is more than 4 ppm then the water goes again thorugh the inlet valve and process continues as in point(1)

j)The salt content or brine water stored in bottom of chamber is ejected by brine ejector at regular intervals and thrown overboard. 

•ALARMS: High salinity alarm 

•SAFETY: Pressure relief valve

•USE OF FRESH WATER ONBOARD:

       Freshwater on board ships is used for a variety of purposes. From domestic uses such as drinking and washing to ship operation purposes such as machinery cooling and cleaning, fresh water is of utmost importance on board ships.