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The Main Parts Of The Freezing Dryer
May 06, 2018

The main parts of the freezing dryer

(1), compressor

At present, most of the refrigeration compressors used in cold drying machines are medium and high temperature type full sealed reciprocating compressors, which are characterized by compact structure, small size, light weight, small vibration, low noise and high energy efficiency. As the main body of the motor and compressor in the fully sealed compressor is sealed in a steel shell, the motor is in the cold medium gas environment, and the cooling condition is better and the life is longer. There is a specified number of lube oil in the lower part of the shell. When the compressor works, it will automatically supply fuel to all parts, and do not need to add lubricating oil at ordinary times. The semi - sealed reciprocating machine or screw compressor is also selected in the large cold drying machine, which are characterized by high cooling power and adjustable load to meet different needs.

2, heat exchange, evaporator

The main function of the heat exchange in the cooling dryer is to use the cold amount of the compressed air cooled by the evaporator (for the vast majority of the users the cold amount is cold) and to cool the compressed air with a large amount of water vapor with this cold measure, thus reducing the heat load of the cold drying mechanism. To save energy. On the other hand, the temperature of the low temperature compressed air rises in the heat exchanger, so that the outer wall of the exhaust pipe will not appear condensation due to the low temperature.

The evaporator is the main heat exchange component of the drying machine. The compressed air is forced to cool in the evaporator. Most of the water vapor is cooled and condenses into the liquid water discharge machine, which makes the compressed air dry. In the evaporator, the convection heat and mass exchange between the air and the cold medium low pressure vapour is carried out. Through the low pressure liquid after the throttling device, the phase change in the evaporator becomes the low pressure cooling medium steam, and the heat is absorbed in the phase transition process, thus the compressed air is cooled.

In order to achieve the highest possible heat transfer effect, it is necessary to increase the heat transfer coefficient, that is, the heat exchange area of the heat exchanger, so the outer wall of the cold dry evaporator and the copper tube of the heat exchanger has adopted the measures of the aluminum fins. At the same time, the fins on the copper tube of the heat exchanger can reduce the impact of the air on the copper tube and avoid the rupture of the copper tube.

(3) condenser and two condenser (pre cooled regenerator)

The function of the condenser in the cold drying machine is to cool the high pressure and superheated refrigerant steam from the refrigerant compressor to the liquid refrigerant and make the refrigeration process continuous. The heat discharged from the condenser includes the heat absorbed by the refrigerant from the evaporator and the heat transferred from the compression work. So the condenser's load is bigger than the evaporator, and the condenser is divided into two kinds: air cooling type (air cooling condenser) and water cooling type (water cooled condenser).

The two condenser (pre cooling regenerator) is the same as heat exchange. The difference is that the heat exchanger is mainly heat exchange of compressed air at high temperature and low temperature, while the two condensing mainly uses the compressed air of low temperature and the high pressure part of the refrigeration system to cool it, so that the cooling medium can be cooled fully, thus the machine platform can be improved. The refrigeration efficiency is also avoided at the same time to avoid the malfunction caused by the poor heat dissipation of the condenser.

Cyclone separator (gas water separator)

Cyclone separator is also an inertial separator, which is widely used in gas solid separation. After the compressed air enters the separator along the tangent direction of the wall, it generates rotation inside, and the water droplets mixed in the gas also rotate together and produce centrifugal force. The centrifugal force produced by the large water droplets is large, and the large water droplets are moved to the outer wall under the action of centrifugal force. Separation.

Hot gas bypass valve

When the compressed air is cooled in the evaporator, there is a lot of condensate. If the evaporating temperature of the refrigerant is too low, the surface temperature of the evaporator copper tube is lower than the ice point under the load condition, then the condensate will freeze in the evaporator, blocking the airflow passage seriously and paralyzing the gas supply pipe. In order to prevent this situation, we must control the evaporation temperature of refrigerants. A simple and effective measure is to add a hot gas bypass valve between the condenser and the evaporator, and the pressure pipe of the hot bypass valve is directly connected with the evaporation pressure. When the evaporation pressure is below a certain degree, the heat gas bypass valve opens automatically, and the high temperature refrigerant steam in the condenser directly enters the evaporator to improve the evaporation temperature and avoid the ice blocking phenomenon.

6. Thermal expansion valve or capillary (throttle valve)

Expansion valve (capillary) is the throttle mechanism of refrigeration system. In the cold dry machine, the refrigerant supply and regulator of evaporator are realized by throttling mechanism. The throttle mechanism causes the refrigeration to enter the evaporator from high temperature and high pressure liquid. When the load changes, the thermal expansion valve adjusts the opening of the valve core by detecting the suction superheating temperature of the compressor, thereby controlling the refrigerant supply into the evaporator. The capillary has a self compensation feature, that is, when the evaporation pressure decreases, the pressure difference between the two ends will increase correspondingly, thus increasing the amount of refrigerant flowing into the evaporator. Because of its simple structure and stable operation, capillary tubes are widely used in small cold dryers.

Automatic drain valve

In the freezing dryer, condensate condensate should be discharged out of the equipment in time to avoid the rising of air water content due to the untimely discharge of condensate water. In order to facilitate the discharge of condensate water, the automatic drainage valve is equipped on the equipment when the water level of the drain valve is not reached to a certain high degree, the pressure of the compressed air will float the ball pressure. When the drain hole is closed, it will not cause air leakage: as the water level in the cup rises (at this time the cooling dryer does not accumulate water), the floating ball opens up to a certain height and opens the drain hole.