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

THE EVAPORATOR. io; enabling the joints to be readily seen, and the coils to be easily detached and replaced when the door is taken off. A smaller door, fitted below the large door, for raking out the scale that falls from the coil. 77. A good deal of scale will also be found to adhere to the inner surface of the casing itself. This deposit, although it is well to remove it, has little influence in reducing the output of the evaporator, as the casing or, at anyrate, the actual shell is not an evaporating surface, but the surface of the steam pocket cast on the shell helps evaporation. 1. Steam Inlet. 78. The inlet steam valve requires but little comment. It should be of the best make, and of ample size for ad- mitting a proper supply of steam to the coils. The inlet to the coils or to steam pocket can be made of suitable size to admit only sufficient steam (when the full steam pres- sure is in the pipe leading to the evaporator) for the maximum pressure specified for the coils. By this means, if the coils are removed, as a specified condition, and the primary steam is allowed to fill the casing, a smaller safety valve can be used for the evaporator casing. 2. Secondary Steam Pipe. 79. This pipe carries the secondary steam, as it is gen- erated by the evaporator, to the distilling condenser. It should be large enough to carry off such steam, without causing any back pressure, for the maximum output of gained or secondary steam. 80. When the evaporator is working at atmospheric pressure, or just above atmospheric pressure, it is con-