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

72 _______________________ SEA WATER DISTILLATION. before, of 1,134 units. But as the primary pressure is now 25 lbs. per square inch, with a latent heat of 927 units, the economy will be 1,134 - 927 = 1’22, assuming that the sensible heat still left in the primary water is wasted ; but if it is not wasted and is used (say for feed- water heating) so as to reduce it to, say, 150°, then the economy will be as follows :— 927 the latent heat of the primary steam at 25 lbs. pressure. 116 the sensible heat left in the primary water after reducing it to 150° (266 - 150=116). _____ 1,043 B.T.U. total. ____ The economy will then be 1,134 * 1,043 = 1 087__i.e., 1 087 economy, or 1’087 lbs. of primary steam to obtain 1 lb. of secondary or gained steam. 13. If, lastly, the primary pressure is at 75 lbs. per square inch, the economy will work out as follows :— There will be the 1,134 units to provide for, as before. Then to meet this requirement we shall have as follows :__ 888 the latent heat of the steam at 75 lbs. pressure, and if no use is made of the sensible heat, 277° left in the primary water, the economy will be 1-277—i.e., 1,134 4- 888. If, however, the heat in the primary water is used, so as to lower it from 320° down to, say, 150°, the economy will then be as follows :— 888 the latent heat, as before. 170 the sensible heat (320 - 150 = 170). 1,058 B.T.U. total. So that the economy will then be 1,134 1’058 = 1'07,