Seawater desalination has been growing rapidly in the past five years, due in part
to the many new membranes that are available to designers. These new
membranes have significantly improved performance, which results in lower
permeate salinity and lower operating pressure. Recently, new low pressure
seawater elements have been developed, and the optimum design with these
elements must be carefully considered. This paper analyzes the trade-offs which
exist when choosing these membranes. In cases of lower feed temperatures,
which are more common in the Pacific coastal area of the USA, and lower salinities,
these lower energy seawater elements can provide sufficiently low permeate
salinity, generally less than 500 mg/l. Alternatively, designers can use hybrid
designs, where higher rejection, higher energy consumption elements are used in
the front of the vessel and lower energy elements are used in the back of the
vessel. This approach results in a feed pressure and permeate salinity between
the two. Use of these new products can result in as much as 1 kwhr/kgal of energy
savings. The advantage of this type of approach is that the lower permeable lead
elements will have lower flux, resulting in a more balanced element flux distribution.
Alternatively, these new membranes can be used in high area configurations,
which have as much as 440 ft<sup>2</sup> of membrane area. The higher area can result in
about $0.1/gpd in capital costs savings. Thus, these new designs offer a variety of
advantages, but detailed analysis is needed to select the optimum element and
configuration. Includes 4 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 730 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 12 |
| Published : | 11/01/2009 |
