Electrode boiler
An electrode boiler (jet type) is a type of boiler that uses electricity flowing through streams of water to create steam. The conductive and resistive properties of water are employed to carry electric current. Technical principle. The most common type of electrode boiler pumps water from the lower part of the vessel to an internal header that has nozzles that allow the water to flow to electrodes. Generally the working pressure is maintained at 10 bar. If more pressure is needed (more steam) the controls speed up the pump to increase flow through additional nozzles. As the needed  pressure is reached the pump controls the flow of water to obtain the desired steam output (in kg per hour) at the desired pressure. On larger systems the pump can be controlled by a variable frequency drive so energy is not wasted. This control system can also control de-aerator pumps and controls. The electrodes are connected to a medium voltage (1-35 kV) AC source. Electrode boilers can work on both single phase and three phase supplies. If DC voltage is used, electrolysis of water occurs, decomposing water into its elements H at the cathode (negative electrode) and O  at the anode (positive electrode). The electrode boiler is 99.9% efficient with almost all the energy consumed producing steam. Losses are radiant heat from the vessel only. During the operation of the boiler, it is fed with water which contains conductive substances like salts. Because the departing steam is free of these substances, conductivity of water increases. With cleaner water in the boiler, the conductivity decreases. When conductivity rises beyond a set limit, some of the water must be removed and replaced with fresh water. The conductivity of the water and the voltage applied determine how much steam is generated  in each stream of water. If water level falls below the limit level, current stops flowing as the circuit is not complete. This stops heating the water and producing steam. When evaporated into steam, deionized or distilled water leaves little or no ions in the boiler respectively. Thus, scale formation is reduced.