PURPOSE: To achieve safe operation, by providing an auxiliary preheater and an auxiliary cooler to detect the shift of heat balance at an early stage by the temp. detector in the preheater of each stage and replenishing steam or low temp. seawater at every stage to make it possible to rapidly recover heat balance.
CONSTITUTION: This water making apparatus is constituted of a multi-effect boiler, which is formed by vertically stacking utility boilers each consisting of an evaporator 1 and a preheater 2 in plural stages and a condenser 3 for condensing the steam flowing out from the final utility boiler. Then, an auxiliary preheater 5 introducing a part of the supplied steam and an auxiliary cooler 6 introducing a part of rejection seawater are provided and separately connected to the preheaters 2 of the respective stages of the utility boilers through control valves 7, 8 to make it possible to introduce steam or seawater corresponding to the variation in the temp. of each of the preheaters 2. As a result, even when an external condition varies, no scale is generated and the effective heat exchange in the utility boiler of each stage is secured to make it possible to rapidly and easily perform stable water making operation.
NAKATANI IKUO
UGAWA NAOHIKO