Causes and Solutions of Ice Blockage in Refrigerated Air Dryers

Causes and Solutions of Ice Blockage in Refrigerated Air Dryers
(1) Moisture ingress during air pressure testing.

Air inherently contains moisture with varying humidity levels. If the cabinet and evaporator remain relatively hot and dry, moisture inside the pressurized air will not easily condense into liquid droplets, 

and water vapor can be evacuated out of the system together with airflow during vacuum pumping.

However, if the cabinet temperature (evaporator temperature) is low (sometimes ice remains inside refrigerated cabinets during maintenance), 

moisture entering during pressure testing will form water droplets or frost adhering to evaporator pipelines.

This frost cannot be removed by vacuum pumping alone. All ice inside the cabinet must be cleared first. Heat the evaporator to vaporize water droplets and frost inside the pipes, 

then perform vacuum evacuation to discharge vapor. This treatment can also be combined with refrigerant charging followed by vacuum pumping.

(2) Moisture is drawn into the system via evaporator leakage when the refrigeration compressor runs. Even after repairing the leak, residual moisture remains inside pipelines. 

Carry out heating, baking and vacuum evacuation with supplementary refrigerant charging.

(3) Moisture enters through evaporator leakage during compressor operation and is sucked into the refrigeration compressor. Since water is heavier than oil, 

water droplets sink to the compressor bottom and are sealed by refrigeration oil, making complete vaporization difficult. This is the primary cause of stubborn ice blockage which is hard to eliminate.

Solution: Run the refrigeration compressor to generate heat and raise the temperature of refrigeration oil. Moisture gradually separates under rotor rotation and elevated oil temperature. 

Conduct continuous vacuum pumping, charge refrigerant and test run. If ice blockage recurs, repeat the above procedures until the fault is eliminated.

Suggestions for Reference:
Emergency handling: Shut down the refrigerated air dryer for half an hour to melt ice, then drain all accumulated water.
Root cause analysis: Check drainage of upstream filters.
a. Inspect drainer performance: Check the timer of electronic drainers; confirm manual blowdown is implemented for every shift. Inspect the drain system of the refrigerated air dryer meanwhile.
b. Air consumption: Check whether actual air consumption decreases significantly. If consumption falls far below the dryer’s rated processing capacity, excess cooling capacity will lead to excessively low air temperature and icing risks.
c. Fan operation: Verify if the fan runs continuously. If yes, inspect the pressure controller.