Transformer and Recti?er provide input power as per electrolyzer requirement. In big size hydrogen plants input power to transformer is at 3.3 KV or 6.6 KV or 11 KV. While in sizes up to 25 NM3/hr, 400 Volts LT power supply is used. MVS Bi-Polar electrolyzer is where high purity DM water is broken to H2 and O2. Hydrogen is evolved on cathode side of cells and Oxygen on anodes of cells. This design makes Electrolyzer unit very compact in size. Hydrogen & Oxygen come out separately from cells into Hydrogen separator and Oxygen separator. Then these are cooled in heat exchangers by cooling water and separated from electrolyte by gravity. Then gases are washed by DM water. Finally clean gases come out through de-misters which are located on top of washers.
Hydrogen coming out from H2 washer unit has moisture saturation and around 0.1 to 0.2% Oxygen impurity. If higher purity is desired, then Hydrogen is passed through a Palladium Deoxo catalyst unit which reduces oxygen to 1-ppm level. Then to dry H2 gas, it is passed through a Molecular sieve Dryer unit where moisture is removed to very low Dew point. It has thermal regeneration heaters and automatic switchover Pneumatic valves. This is a No Purge Loss type dryer with no loss of Hydrogen gas.