Compressed Air System in a Steel Plant...

Compressed Air System in a Steel Plant Compressed air is the air which is kept under a pressure having a value greater than the atmospheric pressure (1.03 kg/sq cm). It is a medium that carries potential energy. Compressed air is a widely used utility in a steel plant. It is an important source of instrument air. Other than instrumentation air which is completely dry and free from contaminants, there are the following three main uses of compressed air in a steel plant. Blast air for blast furnace For the production of oxygen, nitrogen and argon in an air separation plant A utility gas with many uses. Major among it is the operation of pneumatic devices Normally for blast furnace the cold blast air is supplied either by a turbo-blower or an electric blower. In the air separation plant, there are dedicated compressors producing compressed air of the specification needed by the air separation plant for the production of oxygen, nitrogen and argon gases. In case of compressed air being used as a utility gas, steel plants usually have either a centralized compressed air system or/and local compressed air systems. Compressed air is an expensive utility when evaluated on a per unit energy delivered basis. The advantage with the use of compressed air is that it can be easily stored in air receivers and readily available for brief peak demand periods. There are inefficiencies in converting electricity into compressed air as well as line losses in the compressed air distribution. Although the total energy consumption of such systems is normally small, compressed air systems are the most expensive energy in the steel plant due to its very low efficiency. Typical energy efficiency of a compressed air system is around 12 % to 15 %.  Various measures can help...