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

TOO SEA WATER DISTILLATION. than when evaporated at a low pressure, and one would, therefore, be inclined to allow a steam-room somewhat in proportion to the specific volume of the steam evaporated. This, however, would not at all guide one in practice, for take the two pressures of 10 lbs. per square inch, whose steam has a specific volume of 1,009, and 75 lbs. pressure, whose steam has a specific volume of 300, the steam space for the former pressure would be rather over three times the space of the latter, which is not at all in accordance with what is found requisite in practice. It is, therefore, safer to take the steam space from precedent, when it will be found to approximate itself somewhat as follows :— The diameter of the evaporator casing—i.e., the area of the brine surface—will be about in proportion to the weight of steam evaporated in point of time, the pres- sure under which it is evaporated not making very much difference ; it is the quantity of evaporation that is important as regards the area at the brine level. The height of the steam space, on the other hand, does not vary very much with the amount of steam evaporated in point of time, provided a certain minimum height is allowed in all cases. But here again the practice of putting baffles upsets the making of any general or inflex- ible rule that will apply to all cases. Note.—The arrangement of these baffles requires great care, for if placed unsuitably, they may in fact increase the priming by causing a further contraction of the delivery area. 73. In very small evaporators—i.e,., where the pro- duction, in point of time, is very small, say 2 or 3 gallons per hour—the diameter of the casing would become absurdly small, if it was estimated in proportion to the