Desalination plant advantages

Some desalination plants combine distillation with reverse osmosis to produce both power and water. Multistage flash (MSF) processes are used to produce both power and distilled water. The combination of RO and MSF and the advantages of such a combination have been reported (111). 

These composite mendtranes offer some distinct performance advantages over the more conventional RO immbranes, and there is growing interest in their further development. Some la e desalination plants are under construction embodying these membranes. 

Desalination by freezing has also been under development for a number of years, but it has not yet become commercially feasible. This method is based on the fact that when an aqueous solution (in this case, seawater) freezes, the solid that separates from solution is almost pure water. Thus, ice crystals from frozen seawater at desalination plants could be rinsed off and thawed to provide usable water. The main advantage of freezing is its low energy consumption, as compared with distillation. The heat of vaporization of water is 40.79 kJ/mol, whereas that of fusion is only 6.01 kJ/mol. Some scientists have even suggested that a partial solution to the water shortage in Cafifomia... 

The steam transformers produce a medium pressure motive steam using the steam extracted from the turbine. The produced steam is supplied through the thermal vapour compressor (steam ejector) to the evaporator for desalination. One significant advantage of the MED-TVC process is its ability to use pressure energy of the steam for desalination. The performance summary of the SMART nuclear desalination plant is as follows ... 

SMART desalination plant incorporates the falling film multi-effect evaporation with horizontal tubes and a steam jet ejector (thermal vapour compressor). The desalination unit is designed with a plant life of 30 years, performance ratio of 19.6, acid cleaning to be performed once in 12 months, maximum brine temperature of 65°C, and the supplied seawater temperature of 33°C. Thermal vapour compressor is introduced to improve thermal efficiency of the process steam. The advantages of this design are high heat transfer coefficients and a relatively simple operation system. The performance ratio of desalination plant, one of the most important coupling parameters, was optimized based on the sensitivity analysis of water production cost and on the requirements to the SMART desalination plant. 

A combination of nuclear power reactor and seawater desalination plant could be realized in a more economical way, since the higher is the temperature and pressure of steam used in a turbine, the lower is the cost of electricity produced. On the other hand, steam at low temperature and pressure is needed for fractional desalination, and the greater part of inputted heat is the latent heat of steam. Therefore, the power production and desalination systems may be advantageously combined. A 100 MWe FBNR when realized within a cogeneration plant for the production of both power and potable water could produce 70 MWe of electricity and... 

Get More Advantages by Applying Titanimn TVibing not only for Power Plants but also for Desalination Plants , Technical Brochure, Japan Titanium Sodely, May 1984... 

Desalination plants. Thin walled (0.7 mm) titanium tubings have been used with success in multistage flash distillation despite tough competition with cupronickels because of the cost advantage offered by the later. The titanium tubes withstand brine temperatures up to 120°C and are free from impingement attack. Titanium tubes are standard materials in the Gulf countries for brine heaters, heat recovery and heat reject sections. Cost factors have limited their wide applications in desalination plants. 

A variation on the D C contract is to add the requirement for the D C contractor to also maintain the facility for a certain length of time. This has the advantage, from the Owner s point of view, of ensuring that the quality of the facility is appropriate. A further variation on this is for the contractor to build, own (and maintain), and operate the facility for a certain length of time, before transferring it to the Owner, a so-caUed BOOT contract. This is most common for such major infrastructure works as e.g. motorways and desalination plants, but would not be found in manufacturing plants, where the Owner has to be in charge of the daily operation. 

TABLE 33 Advantages and Disadvantages of Desalination Plant Colocation... 

Saline Water for Municipal Distribution. Only a very small amount of potable water is actually taken by people or animals internally, and it is quite uneconomical to desalinate all municipally piped water, although all distributed water must be clear and free of harmful bacteria. Most of the water piped to cities and industry is used for Htfle more than to carry off small amounts of waste materials or waste heat. In many locations, seawater can be used for most of this service. If chlorination is requited, it can be accompHshed by direct electrolysis of the dissolved salt (21). Arrayed against the obvious advantage of economy, there are several disadvantages use of seawater requites different detergents sewage treatment plants must be modified the usual metal pipes, pumps, condensers, coolers, meters, and other equipment corrode more readily chlorination could cause environmental poUution and dual water systems must be built and maintained. 

For this reason, two pass seawater desalination process have been necessarily employed till quite recently, and the results obtained have been satisfactory to some extent with regard to water quality and practical operation. However, one pass process has advantages over two pass process for simple and compact plant, simple operation, easy maintenance and lower energy consumption. 

Small-scale reactors have more advantages than large-scale reactors in variety of energy utilization, construction, maintenance and adoption of innovative technologies, while the latter have scale merits in construction cost. The nuclear energy utilization of small-scale reactors are ship propulsion, electricity generation, heat supply, and sea water desalination, etc. Construction and maintenance for small-scale reactors can be made in factories exclusive use for them, but not at the site of the plant. In small-scale reactors, the safety can be enhanced sometimes by new technologies. 

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