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

MULTIPLE DISTILLATION. 173 multiple distillation; yet one maker may carry the system of successive distillations farther than another, or the feed-water may be differently heated or fed in, or the brine differently discharged, and other points of detail might be mentioned; but these really only affect the arrangement and construction of the apparatus. Note.—As it is obviously impossible to give in detail the construction of every make of distiller and form of apparatus, the system or theory of multiple distillation will alone be explained, and the reader must apply the same to whatever type of apparatus he is interested in. Suitability and Purpose. 6. The apparatus for multiple distillation is most suit- able for large plants or installations, where a considerable amount of pure water has to be produced daily. Where, therefore, the daily (24 hours) production is, say, over 10 tons of water as a minimum, the apparatus for multiple distillation can always be regarded as suitable, on account of the great saving of coal. It also follows that the larger the daily requirement is, the more extended may be the type of multiple distillation adopted. 7. The following may be taken as a rough guide—i.e., where the fuel, say coal, is at normal price, or very cheap, or abundant—as there is no advantage in incur- ring a large outlay on an apparatus, highly economical in its system of working (for every extension of compound distillation necessarily makes the apparatus more expensive), when an apparatus less economical in its system of working will answer the purpose.