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.
Main Feature
DF35/60/2 | L (mm) | D (mm) | H (mm) | SD (mm) | LD (mm) | Weight (kg) |
|---|---|---|---|---|---|---|
| 1480 | 1740 | 2800 | 1727 | 2427 | 2985 |
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| Advatage | Application | Option |
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Working Principle
The main engine jacket cooling water circulates the outside of the vertical tube in heating section and the sea water to be distilled is sent to the bottom cover of this section. Then some of the sea water is converted into vapour when it goes up through the heated tubes. The vapour, through the demisters, is condensed on the outer surface of the tubes of the distilling condenser and the resultant distillate is led to the suction of the distillate pump. In the meantime the non-condensable gases and brine are extracted and discharged to overboard by the combination ejector.
Technical Specification of DX-α Type
| Capacity | Type | Connection | Jacket water flow80°C | Heat consumption | Ejector pumpcapacity | Ejector pumpconsumption(60Hz) | FW pumpconsumption(60Hz) | |
|---|---|---|---|---|---|---|---|---|
| m³/24hr | Single stage | JIS | m³/24hr | KW | m³× bar | KW | bar | KW |
| 5 | DX-α -5 | 65 | 13 | 141 | 13×4.8 | 5.5 | 2 | 0.4 |
| 10 | DX-α -10 | 80 | 26 | 282 | 24×4.8 | 6.6 | 3 | 1.5 |
| 15 | DX-α -15 | 80 | 37 | 423 | 35×4.7 | 11 | 3 | 1.5 |
| 20 | DX-α -20 | 100 | 54 | 564 | 44×4.8 | 11 | 3 | 1.5 |
| 25 | DX-α -25 | 100 | 56 | 705 | 61×4.8 | 15 | 3 | 1.5 |
| 30 | DX-α -30 | 125 | 69 | 846 | 75×4.8 | 18.5 | 3 | 1.5 |
| 35 | DX-α -35 | 125 | 80 | 987 | 75×4.8 | 18.5 | 3 | 1.5 |
| 40 | DX-α -40 | 125 | 85 | 1128 | 90×4.8 | 22 | 3 | 1.5 |
Installation sketch of Fresh Water Generator
Type | L | B | H | C |
| Approx. Weight(kg) | ||
|---|---|---|---|---|---|---|---|---|
| Empty | Operation | Ejector P/P | ||||||
| DX-α -5 | 1480 | 820 | 1430 | 1655 | 650 | 680 | 780 | 120 |
| DX-α -10 | 1680 | 980 | 2005 | 1840 | 830 | 750 | 900 | 120 |
| DX-α -15 | 1835 | 1030 | 1975 | 2030 | 850 | 850 | 1000 | 128 |
| DX-α -20 | 1880 | 1060 | 1680 | 2250 | 990 | 1140 | 1350 | 140 |
| DX-α -25 | 2050 | 1150 | 1850 | 2310 | 1200 | 1145 | 1370 | 175 |
| DX-α -30 | 2250 | 1330 | 2080 | 2470 | 1500 | 1150 | 1400 | 175 |
| DX-α -35 | 2400 | 1380 | 2100 | 2510 | 1500 | 1200 | 1570 | 175 |
| DX-α -40 | 2500 | 1400 | 2205 | 2550 | 1500 | 1320 | 1650 | 187 |
Working Principle
The DongHwa Entec DF Series Fresh Water Generator utilizes the heat from diesel engine jacket cooling water to produce pure drinkable water by evaporating sea water under high vacuum enabling the feed water to evaporate at temperatures below 48°C. Steam can also be used as the heat source instead of the hot jacket water.The DongHwa Entec DF Series Fresh Water Generator is based on 2 titanium plate heat exchangers acting as an evaporator and a condenser respectively.The evaporation chamber is kept under vacuum by a water ejector driven by the sea water outlet from condenser. A part of this heated sea water is used as feed water for the evaporator. The feed water evaporates when entering the evaporating chamber due to the vacuum condition. Water spray and droplets are partly removed from the vapour by the deflector mounted on top of the evaporator and partly by a build-in demister. The separated water droplets fall back into the brine, which is extracted from the sump by means of the ejector pump.The desalted vapour passing through the demister will be sucked into the plate condenser where it will be condensed by means of cold incoming salt water.The pure distilled water will be taken out by means of an integral fresh water pump. The pure water taken out from the condenser will be controlled by a salinometer to supervise that the pre-set salinity(1~10ppm) will be reached. If the salinity exceeds the specified level, the solenoid valve in the discharge line of the distiller pump is automatically activated and the faulty distillate is returned to the feed line.
Technical Specification of DF Type
| Capacity | Type | Connection | Jacket water flow (m³/24hr) | Heat consumption | Ejector pump capacity | Ejector pump consumption (60Hz) | FW pumpconsumption(60Hz) | |||
|---|---|---|---|---|---|---|---|---|---|---|
| m³/24hr | Single stage | JIS | 80°C | 85°C | 90°C | KW | m³× bar | KW | bar | KW |
| 3 | DF3 | 40 | 8 | 6 | 5 | 110 | 8×4.0 | 3.6 | 3.0 | 0.750.75 |
| 5 | DF3 | 40 | 10 | 8 | 6 | 160 | 13×4.0 | 4.8 | 3.0 | 0.75 |
| 7 | DF7 | 40 | 12 | 10 | 8 | 220 | 18×4.0 | 6.6 | 3.0 | 0.75 |
| 10 | DF7 | 65 | 24 | 20 | 15 | 310 | 24×4.0 | 6.6 | 3.0 | 0.75 |
| 12 | DF7 | 65 | 26 | 23 | 16 | 360 | 29×4.0 | 11.0 | 3.0 | 0.75 |
| 15 | DF13 | 65 | 34 | 30 | 22 | 460 | 35×4.0 | 11.0 | 3.0 | 0.75 |
| 18 | DF13 | 65 | 38 | 35 | 25 | 540 | 40×4.0 | 11.0 | 3.0 | 0.75 |
| 20 | DF13 | 65 | 44 | 40 | 30 | 600 | 44×4.0 | 11.0 | 3.0 | 0.75 |
| 25 | DF13 | 80 | 54 | 48 | 35 | 750 | 58×4.0 | 15.0 | 3.0 | 0.75 |
| 30 | DF23 | 10 | 75 | 67 | 50 | 910 | 75×4.0 | 18.5 | 3.0 | 1.5 |
| 35 | DF23 | 10 | 80 | 75 | 55 | 1080 | 88×4.0 | 22.0 | 3.0 | 1.5 |
| 40 | DF35 | 125 | 86 | 80 | 60 | 1220 | 92×4.0 | 22.0 | 3.0 | 1.5 |
| 45 | DF35 | 125 | 100 | 90 | 68 | 1360 | 95×4.0 | 22.0 | 3.0 | 1.5 |
| 50 | DF35 | 150 | 112 | 100 | 74 | 1520 | 120×4.0 | 22.2 | 3.0 | 1.5 |
| 60 | DF35 | 200 | 132 | 118 | 90 | 1850 | 140×4.0 | 24.0 | 3.0 | 1.5 |
