Fault Analysis and Principle Introduction of Air Dryer

Sep 23, 2024

Ⅰ. What is the role of air compressor equipped with cold dryer？

The air compressor freeze dryer mainly uses the refrigerant to exchange heat with compressed air, reducing the temperature of the compressed air to a dew point temperature in the range of 2 to 10°C, so that the water content in the compressed air tends to be supersaturated, thereby removing the moisture in the compressed air to ensure stable production. Compressed air needs to pass through pipelines to reach pneumatic equipment and gas users during production, and compressed air usually contains impurities such as water, oil, and dust, which come from the air. If it is not treated, it will cause pipeline loss, damage to pneumatic equipment, and contact with products, resulting in a decline in product process.

Therefore, it is necessary to configure compressed air purification equipment (air compressor post-processing equipment) to purify impurities in the compressed air, and the Air Compressor Freeze Dryer is one of the devices used to remove moisture. There are two types of air compressor dryers commonly used in the market, freeze dryers (cold dryers) and adsorption dryers (absorption dryers).

The freeze dryer uses refrigeration technology to cool and remove water, and the adsorption dryer uses adsorption materials to absorb moisture in the compressed air for drying. Because of the constraints of its principle, if the temperature is too low, ice will appear, so its dew point temperature is usually 2~10°C. Because the adsorption dryer does not need to go through temperature changes, and the desiccant (aluminum oxide) can perform deep drying, the dew point temperature at its outlet can usually reach below -20°C, which can achieve deep drying. Generally speaking, if the gas consumption is small and there is almost no quality requirement, a Blast Hot Dryer for Air Compressor can be used directly. If the requirements are higher, it is recommended to use an adsorption dryer. In general, the adsorption dryer is superior to the cold dryer in terms of stability and effect.

Ⅱ. What are the reasons for the high exhaust temperature of the dryer?

1. The air compressor compressed air intake temperature is too high or the flow rate is too large

2. The refrigeration system working conditions change, causing the refrigerant evaporation temperature to rise, so that the compressed air cannot be sufficiently cooled in the evaporator

3. The heat dissipation of the outer wall of the precooler pipe is too large

Ⅲ. What are the reasons for the low exhaust temperature of the dryer?

1. The precooler heat exchange area is insufficient and the evaporator has excess cooling capacity

2. The air compressor compressed air intake temperature is low or the flow rate is too small

3. The refrigeration system working conditions change, causing the refrigerant evaporation pressure to be lower than the normal value

Ⅳ. What is the effect of the amount of refrigerant injection on the dryer?

1. If the refrigerant injection is too little, the dryer will experience the following phenomena:

(1) The evaporation pressure and the refrigeration pressure are lower than normal operation, but the air dew point cannot be lowered.

(2) The compressor shell gets hot.

2. Excessive refrigerant injection may cause dryness:

(1) As the refrigerant liquid accumulates in the refrigeration tank, the refrigeration tank area is reduced, resulting in increased refrigeration tank pressure, which may cause high-voltage tripping in severe cases.

(2) The load on the refrigeration compressor increases, making it difficult to start.

(3) The refrigerant is not fully vaporized in the evaporator, causing wet steam to enter the compressor, which poses a risk of “liquid compression”.

(4) As the refrigeration tank pressure increases, the compressor cooling capacity decreases and the air dew point rises.