Frozen compressed air dryer (refrigerated air dryer for short) is an industrial equipment that reduces the dew point of compressed air and removes moisture through refrigeration cycle. Its core components include evaporator, condenser, compressor and heat exchanger, among which the heat exchange chamber in contact with compressed air usually operates under pressure.
Is it a pressure vessel? The key depends on the design parameters.
According to China’s “special equipment safety law” and TSG 21-2016 “safety technology supervision regulations for fixed pressure vessels”, it is necessary to judge whether the equipment belongs to pressure vessels and meet the following three conditions at the same time:
- working pressure ≥ 0.1 MPa (Gauge pressure);
- volume ≥ 25 L;
- the medium is gas, liquefied gas or liquid with the highest working temperature higher than the standard boiling point..
The design pressure of most medium and large refrigerated air dryer evaporators/gas-water separation Chambers is 0. 7–1.0 MPa, the volume usually exceeds 30 L, and the processing medium is compressed air (gas), socomply with the definition of pressure vessel. But small integrated refrigerated air dryer (such as rated throughput < 1 m³/min, cavity volume < 25 L) may be exempted from supervision.
Actual regulatory requirements
refrigerated air dryer of pressure vessels must be designed and manufactured by qualified design units (A2 or D pressure vessel manufacturing license), special equipment product quality certificate is attached to the factory, and the use registration and regular inspection are handled according to regulations.
Evaporator (pressure chamber)
Compressed air inlet
Dry air outlet
Note: The above figure shows refrigerated air dryer pressure-bearing core component-evaporator cavity (blue frame), which directly bears the pressure of compressed air system as the pressure boundary, which is the key part to determine whether it belongs to the pressure vessel.
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