Characteristics of drum dryer precautions for the

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Drum dryer (also known as drum dryer, rotary dryer, etc.) is a kind of contact internal heating and conduction drying machine. In the drying process, heat is transferred from the inner wall of the drum to its outer wall, passes through the dried food materials attached to the outer wall of the drum, and evaporates the water on the materials. It is a continuous drying production machine

drum dryer is widely used in chemical industry, brewing, manufacturing, pharmacy, fertilizer, urban sludge treatment and so on. Now let's introduce the characteristics and precautions of drum dryer. Let's have a look

working principle of drum dryer

the rotating drum of drum dryer is a cylinder that is slightly inclined and can rotate. Wet materials enter from the upper part of one end, and dry materials are collected from the lower part of the other end. Hot air enters from the feeding end or discharging end and is discharged from the upper part of the other end. The cylinder is equipped with a forward board, so that the materials can be lifted and sprinkled continuously during the rotation of the cylinder, so as to make it fully contact with the hot air flow, so as to improve the drying efficiency and move the materials forward. The heat source of drying materials is generally hot air, high-temperature flue gas, steam, etc

the working process of the drum dryer is as follows: the feed liquid that needs to be dried flows into the receiving tank of the drum dryer from the high-level tank, and the material is thinly (film) attached to the drum surface by the film distribution device. The drum is filled with heating medium. Steam is mostly used in the food industry, the pressure is generally 0.2 ~ 6Mpa, the temperature is between 120 ~ 150 ℃, and the material is vaporized by heat transfer through the simple wall during the rotation of the drum, The rolling Jane completes the processes of film distribution, vaporization, dehydration, etc. in one rotation cycle. The dried materials are scraped off by the scraper, and then transported to the finished product storage tank through the screw. Finally, they are crushed or packaged directly. Depending on its nature, the water evaporated during heat transfer can be introduced into the corresponding treatment device through a closed cover for dust capture or emission

drum dryer features

continuous operation, which can get uniform dry products; When drying materials, the drying time of the drum dryer is short, generally about 7-30s. The dried products are not in danger of high temperature. It is suitable for the drying of heat sensitive materials, but the wall may also overheat; No matter the viscosity of the dried material slurry is high or low, it can be dried; High thermal efficiency; Because there will be no residual products in the dryer, a small amount of materials can also be dried; The operating parameters of the drum dryer have a wide range of adjustment and are easy to adjust; The drum dryer is easy to clean and change its purpose; Waste gas does not take away materials, so there is no need to use dust removal equipment and other dryer accessories. Drum dryers are widely used in the drying of slurry materials, such as dry yeast, antibiotics, lactose, starch slurry, sodium nitrite, dyes, calcium carbonate and distillation waste liquid

precautions for drum dryer

the water evaporation capacity of drum dryer is generally 30-80kg/m3· h; It increases with the increase of hot air temperature and changes with the moisture properties of materials. It has higher evaporation intensity than flash drying and spray drying. The thermal efficiency is generally 40% - 70%. It has the following characteristics:

1. High thermal efficiency

because the dryer is heat conduction, the direction of heat transfer is basically the same throughout the heat transfer cycle, so most of the heat supplied in the drum is used for the vaporization of wet materials, and the thermal efficiency is up to 80% - 90%

2. High drying rate

the heat and mass transfer process of the wet film on the cylinder wall, from the inside to the outside, has the same direction, and the temperature gradient is large, so that the film surface maintains a high evaporation intensity, which can generally reach 30 ~ 70 kg/(㎡.H)

3. Stable drying quality

because the heating method is easy to control, the temperature in the cylinder and the heat transfer rate of the intermediate wall can be kept relatively stable, so that the material film can be dried under the heat transfer state, and the product quality can be guaranteed. However, the drum dryer also has its disadvantages, mainly including: due to the high surface humidity of the drum, some products will lose flavor or show abnormal color due to overheating. In addition, if the vacuum dryer is used, the cost is high, and it is only suitable for the treatment of materials with very high heat sensitivity

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