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

160 CHAPTER IX . THE WORKING OF A DISTILLING APPARATUS. Ordinary Ship Double Distiller. 1. An evaporator is simply a boiler worked by steam ; consequently it has a much greater evaporating surface and power than a boiler of the same size heated by coal fire, whilst the quantity of water operated on is only a small fraction of that in a fire-heated boiler of the same evaporative capacity. 2. As the quantity of water in an evaporator is relatively small, and its evaporative surface proportionally so large, it is highly important to make sure that the evaporator is working steadily—i.e., that its brine level is steady— in order to avoid any risk of the water being entirely evaporated off, or of the evaporator being deluged with water, either of which events will happen if reliance is placed on a man in charge adjusting the feed and brining by hand. In the first case, the evaporator will salt up ; in the other, priming will occur and spoil the distilled water. These difficulties may arise in a few moments. 3. The feed-water having to be fed in such large quan- tities, and the evaporation being so large from compara- tively so small a volume of sea water undergoing the operation, and the proper amount of brine discharge being so important, it has been found that an effective arrangement for automatically feeding and brining can alone give satisfaction.