A Practical Manual On Sea Water Distillation
With A Description Of The Necessary Machinery For The Process

________ .. ' __________________________ __________________________ ________________ _______________________________________________________...... J 28 SEA WATER DISTILLATION. tions affect it—e.g., the different construction of evap- orators ; thus in some the tubes are large, as also the water space between them, while in others the coils are small and compact, and the intervening water space less. Moreover, it must be remembered that the smaller evap- orators require a proportionally larger brine surface than do large evaporators. Experience is the only reliable guide as to what is a sufficient brine area. Probably every evaporator maker has a different rule to apply to his evaporator, and his rule would not apply to another maker’s evaporator. (See also “ Steam-Room, p. 99.) 138. Some makers find they can reduce the brine area by the use of baffles placed in the steam-room. This can- not be regarded as wholly satisfactory. If the brine area is not sufficient priming will set in, and baffles will not be of much use. The Admiralty liud a rule that baffles \\ tic not to be used. The form of baffles that are used are very diverse. Some are placed low down, near the surface of the brine, whilst others are placed high up, near the outlet of the steam. (4) Brine Level. 139. The best level for the brine, when the evaporator is at work, has also been a subject of much consideration. With the vertical sheaf of tubes (originally the only form of evaporating surface in use), the best brine level was found to be about three-quarters of the distance up the sheaf—that is to say, the sheaf was immersed in the brine to the extent of three-fourths of its height. The object of this was to allow the upper part of the tube surface to deal with the froth as it rose from the boiling brine, and thus lessen any priming action. Now that the evapor-