*3.6. Instrument Air System*

The quality of the instrument air that is supplied to the compressor station shall be determined in accordance with DIN ISO 8573-1 [34]. In order to deliver the necessary quantity of air, three instrument air compressors have been installed simultaneously, and an additional unit has been set aside as a backup. Piston compressors have been chosen because they provide the appropriate degree of flexibility. A three-stage cleaning process is planned for the area downstream of the compressors. There is a stage dedicated to the removal of liquid droplets, followed by two stages dedicated to the removal of solids. After going through this cleaning process, the air is then sent through an adsorption drier in order to achieve the desired water dew point. One adsorption system will be on duty at all times, while the other will be in standby mode. Following an additional cleaning process, the air is then sent to the instrument air network through a buffer vessel so that it can handle peak demands. After the first stage of filtering, the liquids that have been removed will be sent to an oil/water separation stage before the effluent is disposed of.
