What is the Appropriate Temperature for the Dehumidifying Dryer?

1. Working principle of internal and external circulation of dessicant dryer

Dehumidifiers are also known as dehumidifiers. Dehumidifiers are not only widely used in homes, but also have many roles in plastic auxiliary machinery, and they are also emerging in the pharmaceutical industry. The dehumidifying dryer is mainly used to dry plastics with strong hygroscopicity. The dehumidifying dryer sends the dehumidified low dew point air into one or more standard drying hoppers to improve drying efficiency and shorten drying time.

(1) Internal circulation of dehumidifier

Through the operation of the compressor→discharge high temperature and high pressure gas from the exhaust port→enter the condenser for cooling→turn into low temperature and high pressure gas→through capillary interception→turn into low temperature and low pressure liquid→evaporate and absorb heat through the evaporator→return to the compressor to become Low temperature and low pressure gas. And so on and on.

(2) External circulation of dehumidifier

In the case of normal startup → through the operation of the fan → the moist air is sucked from the air inlet → through the evaporator → the evaporator absorbs the moisture in the air on the aluminum sheet → becomes dry air → passes through the condenser to dissipate heat → from the air outlet blow out.

2. Temperature setting of dessicant dryer

The dehumidifying dryer can improve the drying efficiency and shorten the drying time, and is not limited by the environment to ensure the drying effect. However, due to the different physical properties of different raw materials, the required drying temperature is also different, and a reasonable drying temperature needs to be set according to the actual situation.

Temperature requirements of dehumidifying dryer: when the dehumidifying dryer is at room temperature, that is, 20-25 °C, the dehumidifying dryer is used in a wide range of occasions with a humidity requirement of 10%-50%, while the molecular sieve dehumidifying dryer is used in the temperature requirement of 1%-10% % of special process occasions with very strict temperature requirements. The service life of imported activated silica gel and molecular sieve dehumidification dryers is generally more than five years. The drying time recommended by the supplier of the material to be dried by the dehumidifier dryer is 4hr, and the processing capacity is 100lb/h. To determine whether the air flow of the dehumidifier dryer is sufficient, the temperature profile in the drying silo can be measured. Here, special attention should be paid to the temperature at 4hr (400lb).

If the temperature at the 400 lb level in the drying silo of the desiccant dryer reaches the set value, then the airflow is considered sufficient (the desiccant dryer is not using raw materials). If only the material at 1hr, 2hr or 3hr is fully heated in the drying silo, it means that the air flow cannot complete the heating and drying of the material at the predetermined yield.

If the material is not properly dried after coming out of the desiccant dryer, it should be checked whether the drying silo has enough space to provide sufficient and effective drying time. The effective drying time of a desiccant dryer is the time that the particles are actually exposed to the proper drying temperature and dew point. Also check the return air temperature of the plastic drying machine from time to time. When the return air temperature is high, it may indicate that the size of the dryer is too large for the production rate, or the temperature of the material when entering the drying silo is too high. In order to prevent the return air temperature from becoming high, a heat exchanger needs to be installed on the return air path, to ensure that the desiccant can effectively remove the moisture in the dry air and ensure the drying effect. Since each raw material has different physical properties, such as molecular structure, specific gravity, moisture content and other factors, the drying temperature has certain limitations.

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