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

j44 SEA WATER DISTILLATION. 20. Sometimes the surface allowed for the surface condenser is as follows One square foot of brass tube (18 I.S.W.G.) surface per 30 lbs. of steam at a temperature of 212° to 30 lbs. of water at about 100°, with the circu- lation of 900 lbs. of sea water entering at about 50°, and discharged at about 90°. This would be for ordinary climates, but if the sea water used for the circulation is in the tropics then the surface allowed is 1 square foot per 16 to 20 lbs. of steam to be condensed. AMe.—This works out as follows :— 966 units of latent heat in the steam, 112 degrees cooled down (212— 100 — 112). 1 ,078 (total) x 30 = 33,040 units of heat imparted by the steam. 9 0° temperature of outlet circulation. 5 0° „ inlet 4 0° (difference) X 900 = 36,000 units. That is to say, 33,040 units imparted to, and 36,000 units of heat absorbed by the circulation water; which about balances the heat given and received. If the surface allowed is 1 square foot per 16 or 20 lbs. of water, other conditions being the same, it gives almost double the surface to be allowed for tropical climates. 3 . Dilution and Feed-Water Allowance. 21 As it is usual to take water for diluting the brine from the lower part of the distiller casing, and more circu- lation water from the upper part of the casing for evapor- ator feeding, the total quantity of these two waters should