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

186 SEA WATER DISTILLATION. part of the total output is used as feed for the boiler. This arrangement will keep the boiler free from scale, but the loss will be very great, as it uses the water available for purposes other than feeding the boiler. The reduction will, in fact, be the loss of the 10 tons of water from the ton of coal consumed, thus— In double distillation there will be only 8 instead of 18 tons. treble ?? 55 144 24'4 „ quadruple ? ) J 5 19-52 29-52,, quintuple J 9 5 5 26’6 36'6 „ sextuple 5? 5? 27*9 5 5 37*9 ,, This reduction is absolutely unnecessary if a suitable boiler, worked with sea water, forms part of the apparatus. Right Boiler Pressure—Economy of. 29. From what lias been said on the subject of boiler pressure, it will be observed that the most economical boiler pressure is one that is sufficient, but not excessive, for the lower the working pressure is the greater is the economy. Such a pressure is preferable to a higher one requiring the partial closing of the boiler steam valve. Pump Steam. 30. It must not be forgotten that the above economy is calculated exclusive of the steam required to drive the pump. The pump is a necessary part of the apparatus, and is generally used for nothing else. This pump has to do a good deal of work—e.g., it has (1) to pump circulation water through the condenser, for the purpose of con- densing the steam and cooling the water down to a suit-