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

176 SEA WATER DISTILLATION. (B) SUCCESSIVE DISTILLATIONS. 14. Assume that 1 ton of coal will evaporate 10 tons of water with the boiler used in a given time. The 10 tons of steam thus produced, if led into a condenser, would obviously be re-converted into 10 tons of distilled water, so that the 10 tons of distilled water would be produced by 1 ton of coal, or, put in the usual form of calculation, 1 lb. of coal yields 10 lbs. of distilled water (weight for weight). (1) Single Distillation. 15. The above simple form of distillation is commonly- called “ single distillation,” and the condenser receiving the boiler steam is called the “ distilling condenser.” (The condenser of every distilling apparatus is usually called a “ distilling condenser,” in order to distinguish it from a surface condenser.) The boiler steam may be at any pressure that is convenient. Suppose the boiler pressure is 25 lbs. per square inch, which (as steam) lias a “ sensible ” heat of 266°, and on liquefaction yields 927 B.T.U. ; say also the water fed into the boiler lias an initial temperature of 200°, and that its quantity is 1| times that of the evaporation of 10 tons. The heat required, per pound, is then :— 99 B.T.U. (266 - 200= 66 x 1| = 99). 966 ,, of latent heat. 1,065 B.T.U. per lb. of water evaporated. As there are 22,400 lbs. in 10 tons of steam, 1,065 X 22,400=23,856,000 B.T.U., the quantity of heat needed. A ton of good Welsh steam coal is equal to the require-