Petrochemical facilities depend on compressed air for two critical services: instrument air and process air. Instrument air drives control valves and actuators across the plant, while process air serves purging, oxidation and utility duties. Reliability is paramount, because a loss of air can shut down an entire unit.
Instrument air quality
Instrument air must be very dry, typically a pressure dew point of -40°C or lower, and free of oil and particles. The standard specification is ISO 8573-1 Class 1:2:1 or better, achieved with oil-free compression, adsorption dryers and filtration in a redundant arrangement.
System architecture
- Oil-free screw or centrifugal compressors for the main supply
- N+1 redundancy so maintenance never interrupts supply
- Dual desiccant dryers with automatic switchover
- Receiver capacity to ride through brief peaks
Safety and environment
Classified areas may require special electrical ratings and material selection. Corrosion-resistant coolers and piping suit coastal or aggressive environments, and the control system should alarm early on dew point, pressure or flow deviations.