WSP00451

• File Number: 8273.100
• Description: Colorado River Basin Salinity Control - Federal Agency Reports - BOR
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 11/1/1969
• Title: Cost Analysis of Six Water Desalting Processes
• Water Supply Pro - Doc Type: Report/Study

IV MULTISTAGE FLASH PROCESS

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The multistage flash (MSF) distillation process is currently one

of the leading processes for the desalination of seawater because of

demonstrated performance and favorable economic projections. As a re-

suIt of the importance of the MSF process, a number of studies have been

done on the interrelations among design and operating variables, and

these reports provide a considerable body of useful information.

The two basic configurations of MSF that have received extensive

attention are: the single-effect multiple stage (SEMS) design and the
multieffect, multiple stage (MEMS) layout. Each design has certain ad-

vantages that may make it more favorable in specific applications. The

MEMS configuration has been described as a series of connected SEMS plants

and has the disadvantage of requiring pumps and more complicated piping

between each effect. The advantage of the MEMS design is operation with

either higher temperatures or a higher concentration factor, which re-

suIts in improved thermal efficiency, The SEMS process has the advantage

of design simplicity and proven performance in large-scale plants, while

a high capacity MEMS pilot plant has only recently been constructed.

Dual purpose power/seawater desalting plants are coming to the fore,

and as the capacity of these plants increases, the unit energy costs

will be reduced. The optimum design of these plants will then be toward

lower capital costs for the desalting unit at some sacrifice in thermal

efficiency, As a result, the SEMS design has been selected for most

large-scale plants now under consideration, and it was therefore selected

for this study.

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