Abstract: A water vapor generator having electrodes in a vaporization vessel is disclosed. Current passed through the water between electrodes causes water in the vessel to heat and boil off as steam, make-up water being added when the current drops below a preset minimum value. The make-up water is cut off when a preset maximum value is reached. Thus, the generator operates through successive cycles each containing a descending "boil" leg and an ascending "fill" leg. As water is boiled, its mineral content becomes more and more concentrated, causing increasing its conductivity. To return the water conductivity to its design value the frequency of the boil/fill cycles is measured over several cycles and compared with a predetermined value. If the measured frequency is higher, this indicates a higher than desired water conductivity and a drain cycle is initiated by operating a drain valve. The amount of water drained out of the vessel is proportional to the deviation of frequency from the predetermined value.

Abstract: An improved method of operating a water-vapor generator having a vaporization vessel containing water and provided with heating electrodes therein which are connected to an electric current supply and between which flows an electric current whose magnitude depends on the depth of immersion of the electrodes in the water in the vessel, which method comprises discharging water from the vessel from time in order to reduce the concentration of minerals in the water resulting from vaporization and introducing fresh water into the vessel to replace that which has been evaporated and/or discharged. The method employs the electrode current as a controlled condition for the control of the water supply and discharge valves to the vessel.