(GP/GT) for Additional Water Supply in the Lower Rio Grande

ID-16
a) The separate seawater intake, screening and chlorination plant, pumps, pipework and outfall
system for the power plant condensers can be eliminated.
b) A single steam-raising boiler can replace the separate boilers otherwise required with consequent
savings also in make-up water treatment, fuel storage and handling systems.
c) By expanding the same steam first through a turbine to generate electricity, and then using it to
make water by condensing it in the brine heater of an MSF plant, there is a considerable saving
in total energy use, Le. fuel cost.
d) Common support facilities and services such as control room, offices, workshops, stores,
laboratory, fue system etc. can be used.
e) The total station staff complement for operation, maintenance and administration is hardly greater
than that required for a power station alone.
Combined steam stations producing up to 1000 MW of electric power and 470,000 TID of drinking water
have been built in the Middle East to supply the needs of whole cities. But as well as the combination
with steam turbine power stations, MSF plants can be economically combined with gas-turbine or diesel
power stations, using waste heat boilers installed in the stacks. For small plants though, one of the other
available processes such as Reheat Thermo-compression (RH) or Vacuum Vapor Compression (VVC) is
likely to be more economic.
6. Special Txpes and Applications
New ideas for improving the MSF process, both by novel plant designs and by hybrid combinations with
other processes such as multiple-effect and vapor compression, are constantly being introduced. Few of
these novel ideas have achieved much commercial success, largely due to the conservative nature of the
market. Big desalination plants are an expensive investment and customers tend to be wary of acting as
guinea pigs for trying out unproven systems.
Similarly, many ingenious applications of MSF plant have been suggested, such as salt recovery from
geothermal brines and making irrigation water for agro-industrial complexes. But in spite of the flood
of studies and reports that swell the volumes of conference proceedings, more than 99% of all
commercially installed MSF desalination plant is employed in producing drinking water or boiler feed
water from seawater.
But this is" -not to say that there are no successful advances in MSF plant design. Plant volumes are
gradually becoming smaller; new and cheaper corrosion-resistant materials are being brought into use;
operating regimes are being extended by the introduction of improved chemical additives. Although
Reverse Osmosis is becoming an increasing competitor against MSF, the MSF process itself is benefiting
from the keen competition and is responding to the challenge by cost-saving improvements in design that
will ensure a continuing place in the market for years to come.