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Desalination Plants

A natural water cycle occurs on the earth's surface whereby seawater is evaporated by solar energy and turned into rain to make rivers, which return the water to the sea.
There are areas, however, where it is difficult for this water cycle to occur and inhabitants suffer continually from a shortage of fresh water; for example the Middle East, isolated islands, and areas where no big rivers flow nearby.
Hitachi Zosen contributes to societies and people living in such areas by constructing seawater desalination plants to create artificial water cycles.

Desalination Plant (Oman)
Completed : 2003
Water production : 31,300m3/day×3unit

Major products

MSF (Multi-stage flash)method

The multi-stage flash method is an evaporation process for desalination in which heated seawater is evaporated in a vacuum evaporator and the resulting vapor is condensed to produce fresh water. Recovery of the latent heat of condensed vapor increases the heat efficiency. In the Middle East most desalination plants are constructed with power generation facilities. Therefore many large MSF desalination plants are operated using the excess steam from the power generating facility. Hitachi Zosen has built 15 plants and 42 desalination units since 1978 (total water production: 1,150,000 m3/day).

MSF Desalination Plant (UAE)
Completed : 2006
Water production : 56,825m3/day×2unit


Abundant records of successful operation
Abundant records of successful operation have been established in the field of large-capacity desalination plants throughout the world.
Suitability to extra-large capacity plants
This process is suited to extra-large capacity plants since the capacity of each individual unit is large. In recent times unit capacity has reached 75,700 m3/day and greater.
Stable and reliable performance
This process is not affected by changes in quality (such as salinity or turbidity), thus it provides stable and reliable performance and operation.
High performance
At Hitachi Zosen we have been able to greatly enhance our performance in energy consumption through continued efforts to improve and broaden our operational experience.

Records of delivery

Total construction record  : 15 plants
Number of the total units   : 42 units
Total water production    : 1,150,000m3/day

Records of delivery (from 1982 onward)

Country Water production (capacity of single unit x number)
Oman 28,000m3/day×1unit
Saudi Arabia 24,300m3/day×10unit
Oman 28,000m3/day×2unit
Oman 28,000m3/day×1unit
UAE 15,000m3/day×1unit
Oman 28,000m3/day×1unit
Saudi Arabia 35,000m3/day×8unit
UAE 35,000m3/day×3unit
Oman 31,300m3/day×3unit
Algeria 29,629m3/day×3unit
UAE 56,825m3/day×2unit
UAE 16,800m3/day×2unit

MED (Multi-effect desalination) method

The multi-effect desalination method is an evaporation process for desalination that efficiently produces fresh water through multiple-effect evaporation. The heat source for the first effect is steam from a power generating or other facility, while the heat source for the second and later effect is the steam generated in the previous effect. Evaporation is repeated in both effects. MED can be categorized into three types according to the shape of the heat transfer area: the Vertical Tube Evaporator (VTE), the Horizontal Tube Evaporator (HTE), and the Multi-Effect Plate (MEP). Hitachi Zosen first entered into the desalination market with a VTE multi-effect desalination plant in the 1960s. Thereafter we started to develop the HTE in 2001 and have completed various demonstration tests. The first fully operational system commenced operations in July 2011.

MED Desalination plant (Japan)
Completed : 2011
Water production : 1,300m3/day×1unit


High efficiency
MED has a high heat transfer efficiency because condensation and evaporation occur on both the inside and outside surfaces of the heat exchanger tube. Even higher efficiency is achieved by adopting a thermo compressor.
Low power consumption
MED is the desalination process with the lowest power consumption consuming only approximately 40% of the power of the reverse osmosis method (RO).
Stable performance
This process is not affected by changes in seawater quality (such as salinity or turbidity); thus it provides stable and reliable performance and operation.

Records of delivery

Total construction record  : 8 plants
Number of the total units   : 8 units
Total water production    : 8,600m3/day

Records of delivery (from 1982 onward)

Country Water production (capacity of single unit x number)
Japan 1,300m3/day×1unit
Japan 1,300m3/day×1unit
Japan 800m3/day×1unit
Japan 1,300m3/day×1unit
Japan 800m3/day×1unit

RO (reverse osmosis) method

The reverse osmosis method is a process for producing fresh water by supplying seawater to a semipermeable membrane at higher pressure than osmotic pressure. Unlike the evaporation method it does not require steam and can produce fresh water with a high energy efficiency. In the Middle East, where the cost for energy is relatively low, the evaporation method prevails. However, RO is now expanding its share of the worldwide market, helped along by improvements in technology and membrane performance. At present, more than one half of desalination plants use the reverse osmosis method. Hitachi Zosen has been developing this process with its own technology since the 1970s and has many records of delivery to mainly isolated islands in Okinawa.

RO Desalination Plant (Japan)
Completed : 1986
Water production : 240m3/day×1unit


Low energy consumption
As the process uses mass transfer operations not including the phase transition, energy consumption for desalination is the lowest of all desalination methods.
Easy operation and maintenance
Since the process is simple and operates at normal temperatures, operation and maintenance are easy.
Recovery of energy
Power consumption can be reduced with the energy-recovery system that recovers the pressure of concentrated seawater.
Short deliverly time
The system consists of relatively small pieces of equipment only, so the delivery period is short.

Records of delivery

Total construction record  : 19 plants
Number of the total units   : 35 units
Total water production    : 8,200m3/day

Records of delivery (from 2000 onward)

Country Water production (capacity of single unit x number)
Japan 180m3/day×2unit
Japan 170m3/day×2unit
Japan 170m3/day×2unit
Japan 180m3/day×1unit
Japan 120m3/day×2unit
Japan 185m3/day×2unit
Japan 150m3/day×2unit
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