Fresh Water Generator
Fresh Water Generator is used to desalinate seawater for the ships. There are two types fresh water generator, R/O type and Low-pressure vapor type. Low-pressure vapor type is most widely used in commercial ships because it utilizes wasted engine jacket water or steam while sailing. The engine jacket water and steam can be utilized as a heat-source, and Shell & Tube type and Plate type are available.
The seawater is heated by various heat-sources under the vacuum state, and then vaporized accordingly. The vaporized seawater is desalinated in separate filtering unit before condensed, and then fresh water is produced. Meanwhile, a salinity of produced fresh water shall remain at 0~10 ppm .
Fresh Water Generator is comprised of vaporizer, condenser, demister, salinometer, distillate pump, ejector and steam injector.
Multi-stage Fresh Water Generator can achieve high efficiency when large amount of fresh water is required with small amount of calories due to lack of heat-source. This can be classified into MSF and MED type. Multi-stage Fresh Water Generator is manufactured under the license of CRC, United Kingdom.
Introduction
The DongHwa Double Effect Type Water Maker is the equipment that convert seawater or exhausted dirty water to pure water for drinking, boiler make-up, domestic use on ship and small power station.At that time, seawater is evaporated at about 70°C, 45°C respectly as the one passed the inside of heater under the high vacuum condition and the separated pure vapor is converted to freshwater on condenser.(stage2)The other one is going to the heating medium of heater and then converted to freshwater.(stage 1)
The DongHwa Double Effect type water maker utilizes the waste heat from diesel engine jacket cooling water to convert seawater into freshwater by evaporating under low vacuum condition.The DongHwa Double Effect Type water maker is based on 3sets of Titanium plate heat exchangers as stage 1 evaporator, condenser and stage 2 evaporator respectively.
Operating Principle
The evaporation chamber are kept under vacuum by a water ejector driven by the seawater outlet from the evaporator. The feed water evaporators when entering the evaporators due to the vacuum condition. Water spray and droplet are partly removed from the vapor by the deflector mounted on top of each evaporator and partly by a build-in demister. The separated water droplets fall back into the brine, which is extracted from the lower part of the unit by means of the ejector.The desalted vapor passing through the demister will be sucked into the condensers where it will be condensed by means of cold incoming seawater. The pure distilled water will be taken out by means of freshwater pump.The pure water taken out from the condensers will be controlled by a salinometer to supervise that the salinity level be satisfactory. If the salinity exceeds the preset level, the solenoid valve in the discharge line of the distiller pump is automatically activated and faulty distillate is dumped into the drain. The salinometer has a built-in alarm and can be connected as remote alarm so that a too high salinity is registered immediately in the control room or where else needed.
from www.dh.co.kr
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