Princeton
Invention # 06-2206
The availability of fresh water for drinking, domestic and industrial
uses is a growing problem in many parts of the world. Reverse osmosis and
evaporation methods are currently in wide use for water remediation, notably in
Saudi Arabia where potable water is produced on a large scale from sea water.
Electrodialysis and freezing methods have been less applied. The economics of
all these processes depend on the water source and on the facilities and
environmental problems at the intended site.
Researchers in the Engineering Department at Princeton University have
developed a novel method for the production of fresh water using alkane hydrates
(clathrates).The Princeton method outlines a process which overcomes the high
cost associated with using alkane hydrates. This novel method uses a separation
method in which the hydrate is formed at the temperature of the source water and
at a pressure between one atmosphere and (preferably) less than 10 atmospheres,
with a method for performing nuclei to minimize pressure and accelerate growth
of the solid phase. The source water (e.g., the sea) acts as the heat sink for
forming hydrate and as the heat source for melting separated hydrate in a
process in which the pressure is cycled between one and 10 atmospheres or
less
The hydrate formers meeting the required pressure-temperature properties
may be simple one-component hydrates or complex hydrates or combinations of
simple and complex hydrates. With complex hydrates the primary clathrate former
gives a structure in which the small secondary cavities can be filled with one
or more second guest species, thereby raising the melting temperature at a given
pressure. The hydrate formers can be gaseous or liquid over all or part of the
pressure cycle, offering a range of design options. If the hydrate formers are
liquids, clathrate formation can be accelerated by the addition of dilute safe
oil-soluble surfactants to increase the interfacial area. The clathrate formers
can be biologically safe and readily removed from the fresh product for
recycling at the decompression stage. The heat-sink water from the high pressure
clathrate formation stage may be recycled to improve the heat source in the
decompression stage, or vice-versa for partial pre-cooling. Advantage may also
be taken of the difference of water temperatures at different depths at the
plant site. The hydrate is formed as a pump- able slurry separable by coarse
filtration, gravity or mild centrifugation prior to decompression to recover the
fresh water and recycle the clathrate formers.
Several hydrocarbons which show clathrate formation at temperatures and
pressures appropriate for the proposed process have been identified as
candidates for a design study on a range of source water chemistries and
temperatures. Research for other multi-component hydrates will expand the
temperature and pressure choices for plant designs relevant to particular
locations
Princeton is currently seeking industrial collaborators to further
develop and commercialize this technology. Patent protection is
pending.
For more information on Princeton University Invention # 06-2206, please
contact:
Laurie Tzodikov
Office of Technology Licensing and Intellectual
Property
Princeton University
4 New South Building
Princeton, NJ 08544-0036
(609) 258-7256
(609) 258-1159 fax
tzodikov@princeton.edu