Optimizing the process for emptying carbon dioxide cylinders used for hydrogen sweeping in high-power electrical generators

High-power alternators in large thermal power plants are generally cooled by hydrogen. Operating an electric power generator produces large amounts of heat that must be removed to improve efficiency. This means that the filling and emptying process needs to be performed in an inert atmosphere. Operating experience has shown that carbon dioxide is the most suitable fluid for this purpose because its molecular weight is considerably higher than that of hydrogen. On average, 90% of the contents of each cylinder are in a liquid state. As the process for discharging the cylinder proceeds, the gas progressively gets cool and may give rise to what is referred to as “dry ice,” rendering useless the rest of the content. This article describes the study and implementation of an experimental solution that optimizes the emptying of these cylinders in a power plant, thereby making a considerable saving because of their better exploitation.