Difference between suction dryer and cold dryer

There are significant differences between the suction dryer (adsorption dryer) and the cold dryer (freeze dryer) in many aspects, which are mainly reflected in the working principle, drying effect, energy consumption, maintenance cost and applicable scenarios. The following is a detailed comparison:

1. working principle

• suction dryer based on the principle of pressure swing adsorption, adsorbents (such as activated carbon, alumina, molecular sieve, etc.) are used to selectively adsorb water molecules in compressed air to achieve the purpose of drying. The suction dryer usually contains two or more adsorption towers, and continuous drying is achieved by alternating adsorption and regeneration processes. In the adsorption stage, the wet air passes through the adsorbent layer, and the water molecules are adsorbed; in the regeneration stage, the adsorbent is regenerated by reducing the pressure in the adsorption tower or heating, and the adsorbed water is released.
• Cold dryer: According to the principle of freezing and dehumidification, the heat exchange between the refrigerant and the compressed air is used to cool the compressed air below the dew point temperature, so that the water molecules in the air are condensed into liquid water and discharged out of the machine to achieve drying. Cold dryer usually contains evaporator, condenser, compressor and other components, through the refrigeration cycle to achieve continuous dehumidification.

2. drying effect

• suction dryer due to the efficient adsorption performance of the adsorbent, the suction dryer can usually reach a lower dew point temperature (-20 ℃ to -70 ℃), so the drying effect is better, and it is suitable for occasions with high requirements on the drying degree of compressed air.
• Cold dryer: Limited by the principle of refrigeration and condensation temperature, the dew point temperature of the cold dryer is usually between 2°C and 10°C, and the drying effect is relatively poor. It is suitable for occasions where the degree of drying is not high.

3. energy consumption

• cold dryer: Dehumidification is realized through the refrigeration cycle, and the energy consumption is relatively high. The cold dryer needs to adapt to higher power supply to support processes such as refrigerant compression.
• suction dryer: Almost no additional energy is consumed in the adsorption phase, and only a certain amount of energy is consumed in the regeneration phase. Therefore, although the overall energy consumption is relatively low, it should be noted that the suction dryer will consume a certain amount of regeneration gas (ie, part of compressed air) during the regeneration process, and this part of the gas loss should also be considered in the total energy consumption.

4. maintenance costs

• cold dryer: The main maintenance cost includes the maintenance of the refrigerant system and the cleaning of the heat exchanger. The structure of the cold dryer is relatively complex, the system components are more, and the probability of failure is larger.
• suction dryer: It is necessary to replace the adsorbent regularly and check the sealing of the adsorption tower. Although the suction dryer may fail under the condition of frequent valve action, the overall maintenance cost is equivalent to that of the cold dryer, depending on the equipment model, use conditions and other factors.

5. applicable scenarios

• suction dryer suitable for the high degree of compressed air drying requirements, the gas source stability requirements of the occasion, such as electronics, pharmaceutical, precision instruments and other industries.
• Cold dryer: Suitable for occasions where the degree of drying is not high, such as general industrial manufacturing, construction and other fields. In addition, because the cold dryer does not need to consume regeneration gas and the maintenance is relatively simple, it also has certain advantages in occasions where the gas consumption is large and the drying degree is not high.

In summary, there are significant differences between the suction dryer and the cold dryer in terms of working principle, drying effect, energy consumption, maintenance cost and applicable scenarios. In the selection should be based on specific needs and conditions of use for comprehensive consideration.