Drum dryers are widely used in chemical industry, brewing, manufacturing, pharmaceuticals, fertilizers, and urban sludge treatment. The following Xiao Bian will introduce to you the characteristics of the drum dryer and the use of matters needing attention, let's look at it together.
Roller dryer working principle
The drum of the drum dryer is a cylinder that is slightly tilted and can rotate. Wet material enters from one end and dry material collects from the other end. Hot air enters from the feed end or the discharge end and is discharged from the upper end of the other end. The cylinder is equipped with a forward copy board so that the material is continuously picked up and sprinkled during the rotation of the cylinder, so that it is fully in contact with the hot air flow to increase the drying efficiency and move the material forward. The heat source of the dry material is generally hot air, high-temperature flue gas, water vapor, and the like.
The working process of the drum dryer is as follows: the material liquid that needs to be dried flows from the high position trough to the material receiving trough of the drum dryer, and the cloth film device makes the material thin (membrane) attached to the surface of the drum, and the drum is provided with heat supply Medium, the food industry mostly uses steam, the pressure is generally 0.2 ~ 6MPa, the temperature is between 120 ~ 150 °C, the material in the drum rotation by the simple wall heat transfer to make it wet vaporization, roll in a rotation cycle to complete the film , Vaporization, dehydration and other processes, the dried material scraped by a scraper, the screw conveyed to the finished product storage tank, and finally crushed or directly packaged. The water evaporated in the heat transfer, depending on its nature, can be introduced into the corresponding treatment device to capture dust or discharge, through a sealed enclosure.
Drum dryer features
Continuous operation, can get even drying products; drum dryer drying time in the drying of materials, usually about 7-30s, the drying of the product is not in danger of high temperature, suitable for heat-sensitive materials, drying, but the wall may also produce overheating No matter whether the viscosity of the dry material slurry is high or low, it can be dried; the thermal efficiency is high; because there is no residual product in the dryer, a small amount of material can also be dried; the operation parameters of the drum dryer are adjustable and easy to adjust; The drum dryer is easy to clean and easy to change; the exhaust gas does not carry materials, so there is no need to use dryer accessories such as dust removal equipment. Drum dryers are widely used for the drying of pulpy materials, such as dried yeast, antibiotics, lactose, starch pulp, sodium nitrite, dyes, calcium carbonate, and distillation wastes, etc. can be dried.
Drum dryer precautions
The water evaporation capacity of the drum dryer is generally 30-80 kg/m3·h; it increases with the increase of the hot air temperature, and changes with the moisture nature of the material. It has higher evaporation intensity than flash drying and spray drying. Thermal efficiency is generally 40%-70%. It has the following features:
1, high thermal efficiency
Because the dryer is heat conduction, the heat transfer direction is basically consistent throughout the heat transfer cycle. Therefore, most of the heat supplied in the drum is used for vaporization of the moisture of the material, and the thermal efficiency reaches 80% to 90%.
2, drying rate
The heat transfer and mass transfer process of the wet film on the drum wall is consistent from the inside to the outside in the same direction and the temperature gradient is large, so that the surface of the material film maintains a high evaporation intensity, generally up to 30-70 kg/(m2.h). ).
3, stable drying quality
Because the heating method is easy to control, the temperature inside the barrel and the heat transfer rate of the partition can be kept relatively stable, so that the material film is dried under the heat transfer condition, and the quality of the product can be guaranteed. However, the tumble dryer also has its disadvantages, mainly due to the high humidity of the surface of the tumbler, which may damage the flavor or abnormal color of some products due to overheating. In addition, if a vacuum dryer is used, the cost is high and it is only applicable to the treatment of very heat-sensitive materials.
The above is a brief introduction for Xiaobian. If you want to know more related information, please continue to pay attention to Qijia Consulting. More exciting consultation, please stay tuned.
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