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

I?8 SEA WATER DISTILLATION. primary water in the evaporator tubes, imparts its latent heat of 927 B.T.U., which is about 87 per cent, of 1,065 (but which, owing to inevitable losses, may be reduced to about 80 per cent, in practice), thus giving— 10,650 B.T.U., as before (for the 1 ton of coal). 8,520 B.T.U.—i.e., 80 per cent, of 10,650. 19,170 B.T.U. (total) obtained by the consumption of 1 ton of coal, imparting 10,650 B.T.U. So that double distillation yields a ratio of 18 to 1 (i.e., 18 tons of water per 1 ton of coal) instead of 10 to 1 in the case of single distillation. Thus— As 10,650 : 19,170 : : 1 : 1’8, and 18 x 10 = 18 tons of water. (3) Treble Distillation. 17. By interposing a second evaporator, the boiler, 1st evaporator, and 2nd evaporator are linked together into what is called treble distillation. Boiler Pressure. 18. In this case the initial pressure in the boiler must be increased ; assume it to be 75 lbs. per square inch. The pressure in the 1st evaporator and 2nd evaporator coils will then be intermediate between the primary pressure of 75 lbs. per square inch, and the final pressure (which call the tertiary preäsure) at or near zero. What the working pressure is inside the coils of the 2nd evaporator and in the casing of the 1st evaporator will be considered presently, but by the extension of principle, the gain of distilled water per ton of coal will be as follows :—