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

THE EVAPORATOR. I I 5 which should be kept closed, so as to prevent substances falling in which might interfere with its action. 103. It should be borne in mind that the feed inlet to the regulator has often a considerable head of water over it (say 30 feet), and precautions should be taken to prevent this pressure overcoming the action of the regulator. There is usually a cock on the feed pipe leading to the regulator for this purpose. 3. Temperature—Heaters. 104. It has been shown that the quantity of the feed enters into the question of the economy of the evaporator, but the temperature of the feed is also important, indeed more so than the quantity, for if the feed is very hot the quantity is relatively of less consequence. 105. There are two ways of imparting heat to the feed- water by utilising heat that would otherwise be wasted or thrown away. (1) One way is to utilise the latent heat yielded by the secondary steam when converted into water. (2) The other way is to utilise the sensible heat of the primary water as it is blown from the coil drain, the tem- perature of which is practically the same as that of the steam before it was converted into water. 108. Take method (1) first—that is, by using the latent heat imparted by the secondary steam to the circulation water passing through the distilling condenser. Although a description of the distilling condenser has not yet been reached, it can easily be realised that by taking part of the circulation water from the upper part of the distiller casing, the heat (which would otherwise be wasted by going away with the discharged circulation water) can be