Advanced MED process for most economical sea water desalination

New Trend in the Development of ME-TVC Desalination System

“…In contrast, the last brine temperature, T n is kept at least 2°C greater than the feed water temperature, T f (El-Dessouky & Ettouney, 2002), which is assumed to be 10°C greater than the cold end temperature of the model, T c . The minimum temperature drop per effect including all thermodynamic losses is close to 1.5 -2°C (Ophir & Lokiec, 2005) and the maximum temperature drop per effect is set as an upper limit equal to 5°C, and making it higher than this value leads to high top brine temperature and consequently high operating cost (Michels, 2001). …”

An improved model for multiple effect distillation

“…Additionally, MED provides higher overall heat transfer coe cients by utilizing primarily latent-heat transfer and avoiding the lower speci c heat transfer surface areas associated with sensible heat transfer found in MSF [1]. The ability to operate at low temperature and use low grade heat from power station turbines as the primary heat source for MED yield very low speci c energy costs for seawater desalination and allows the use of lower grade materials for heat transfer tubes (e.g., aluminum alloys) and the evaporator body (e.g., carbon steel epoxy coated shells) [2]. As a result, MED systems are established in many locations within the Kingdom of Saudi Arabia with capacities ranging from 1,500 800,000 m 3 /day [3].…”

Development of an Environmental Impact Assessment and Decision Support System for Seawater Desalination Plants

“…Large MED plants often incorporate thermal vapor compression, where the pressure of the motive steam is used in addition to the heat of the steam in order to increase the efficiency of the process. Moreover, MED plants have a lower potential for scaling due to lower operating temperatures and a lower potential for corrosion due to the use of other construction materials, such as corrosion-proof plastic materials and coatings, aluminum or titanium [136,137]. A disadvantage of MED is that scales form on the outside surfaces of the tubes and therefore cannot be mechanically removed by circulating sponge balls through the tube system, as in MSF plants.…”

“…High temperature MED plants operate at 110 • C and low temperature MED plants at 70 • C [135], with the latter being more common. As the MED process results in a very low temperature drop of 1.5-2.5 • C per effect, a sufficient number of effects can be incorporated even at low temperatures so that comparatively high performance ratios are achieved [136]. MED plants can be configured to function with less cooling water, resulting in a higher temperature rise (of over 20 • C) of the reject than with MSF.…”