Why Is the Air Receiver Tank Arranged in the First Position in the Aftertreatment System of Air Compressors

The vast majority of air compressor units are equipped with a compressed air cooler. During compressor operation, 

hot compressed air separated by the oil-gas separator flows into the compressed air cooler for cooling. In the cooling process, 

water vapor inside the air reaches a supersaturated state and precipitates into condensed water (the amount of condensed water is proportional to discharge pressure and ambient humidity). 

The medium discharged from the air compressor outlet is slightly oily compressed air (oil content ≤3 PPM) mixed with condensed water.

The most common aftertreatment configuration is: Air Compressor + Air Receiver Tank + Class C Filter + Refrigerated Air Dryer + Class T Filter + Class A Filter. Other types of aftertreatment layouts are shown in Figure 1.
Figure 1 Configuration Diagram of Air Compressor Aftertreatment System
Reasons for Placing the Air Receiver Tank at the First Position of the Aftertreatment System
The air receiver tank has three core functions: temperature reduction, water removal and pressure stabilization.

Generally, the temperature of compressed air at the compressor discharge port is 10~15°C higher than ambient temperature. Compressed air exhausted from the compressor flows directly into the air receiver tank. 

As the high-speed airflow hits the tank wall and converges inside, the air temperature drops rapidly. A large amount of water vapor further liquefies and forms additional condensed water.

The inlet and outlet pipelines of the air receiver tank adopt the bottom-in top-out layout, allowing massive condensed water to settle at the tank bottom. 

A drainer installed at the bottom discharges accumulated water periodically, so most condensed water is removed by the receiver tank. 

(The settled condensed water can also capture tiny oil droplets, delivering a certain degree of oil removal effect.) Meanwhile, the temperature of compressed air decreases further,

significantly lowering the load of subsequent filters and refrigerated air dryers.

For this reason, regular draining of the air receiver tank is constantly emphasized by nearly all professionals in the air compressor industry