What Is (ATFD) Agitated Thin Film Dryer ?

An Agitated Thin Film Dryer (ATFD) is a type of dryer used for the continuous drying of a liquid or slurry into a powder or granular form. The ATFD operates on the same principle as an Agitated Thin Film Evaporator (ATFE) where a thin film of the liquid is created on the surface of a heated drum or tube. However, in the ATFD, the heated surface is used to evaporate the liquid, leaving behind a solid residue.

The ATFD consists of a cylindrical vessel or drum that is heated by steam or hot oil. The material to be dried is introduced into the vessel and is spread evenly onto the heated surface. As the drum rotates, an agitator within the vessel breaks up the material into a thin film, allowing for rapid evaporation of the liquid. The solid residue is then scraped off the surface of the drum and collected at the bottom of the vessel.

The ATFD has several advantages over other types of dryers, such as its ability to handle heat-sensitive and viscous materials. The thin film of liquid on the heated surface provides a large surface area for evaporation, allowing for rapid drying with minimal thermal degradation. The agitator within the dryer also helps to prevent material buildup on the heated surface, ensuring efficient and consistent drying.

The ATFD is commonly used in the pharmaceutical, food, and chemical industries for the drying of products such as powders, granules, and flakes. It is also used for the production of instant coffee, tea, and soup powders. Overall, the ATFD is a highly efficient and versatile dryer that offers significant advantages in terms of speed, quality, and product consistency.

ATFD Working Principle

The Agitated Thin Film Dryer (ATFD) operates on the principle of creating a thin film of the liquid or slurry on the surface of a heated drum or tube, and using the heat to evaporate the liquid, leaving behind a solid residue.

The process begins with the material to be dried being introduced into the cylindrical vessel or drum of the ATFD. As the drum rotates, an agitator within the vessel spreads the material into a thin film on the heated surface of the drum. The heat source, typically steam or hot oil, is supplied to the outer surface of the drum, which heats the drum and the thin film on its surface.

The thin film of the liquid or slurry is heated to the boiling point, causing the liquid to evaporate, leaving behind a solid residue. The agitator within the dryer helps to prevent the material from sticking to the heated surface of the drum, ensuring efficient and consistent drying. The solid residue is scraped off the surface of the drum and collected at the bottom of the vessel.

The ATFD is designed for continuous operation, with a steady supply of the material to be dried fed into the vessel, and the dried product discharged at the other end of the drum. The process is controlled by adjusting the speed of the drum rotation, the temperature of the heating medium, and the flow rate of the material being fed into the vessel.

Overall, the ATFD is a highly efficient and versatile dryer that offers significant advantages in terms of speed, quality, and product consistency, making it a popular choice in the pharmaceutical, food, and chemical industries.

Advantages Of Agitated Thin Film Dryer

The Agitated Thin Film Dryer (ATFD) has several advantages over other types of dryers, including:

High thermal efficiency: The thin film of liquid on the heated surface provides a large surface area for evaporation, allowing for rapid drying with minimal thermal degradation. The heat transfer coefficient in the ATFD is much higher than in other types of dryers, resulting in higher thermal efficiency.
Minimal product degradation: The ATFD is ideal for drying heat-sensitive and viscous materials because of the low residence time and low operating temperature. This results in minimal product degradation and a high-quality final product.
Continuous operation: The ATFD is designed for continuous operation, with a steady supply of material fed into the vessel and the dried product discharged at the other end of the drum.
Compact design: The ATFD has a compact design, which makes it easy to install and operate in a small space.
Low maintenance: The ATFD has few moving parts, which reduces the need for maintenance and lowers operating costs.
High product consistency: The ATFD provides high product consistency due to the efficient and uniform drying process.

Features Of Agitated Thin Film Dryer

Agitated thin film dryers (ATFDs) are commonly used in the chemical, pharmaceutical, and food industries for drying heat-sensitive materials. Some of the key features of ATFDs include:

High heat transfer coefficient: ATFDs have a high heat transfer coefficient due to the agitation of the thin film of the product. This allows for efficient and rapid heat transfer, leading to faster drying times.
Short residence time: The short residence time in ATFDs ensures that the product is exposed to high temperatures for only a short period of time, reducing the risk of thermal degradation.
Agitation: The agitated thin film ensures that the product is constantly exposed to fresh heating surfaces, preventing the formation of a hard crust or sticky layers that can impede the drying process.
Continuous operation: ATFDs can be operated continuously, allowing for a high throughput and consistent product quality.
Minimal product holdup: The design of ATFDs minimizes the product holdup, ensuring that the product is quickly and efficiently removed from the dryer.
Versatile operation: ATFDs can be operated under vacuum or atmospheric pressure and can handle a wide range of feed materials, making them suitable for a variety of applications.
Low maintenance: The simple design of ATFDs and the lack of moving parts make them easy to operate and maintain.

Overall, ATFDs are a reliable and efficient choice for drying heat-sensitive materials.

Application Of ATFD

Agitated thin film dryers (ATFDs) are widely used in a variety of industries for drying heat-sensitive materials. Some common applications of ATFDs include:

Chemicals: ATFDs are used to dry a variety of chemical products, including organic and inorganic chemicals, resins, polymers, and pigments.
Pharmaceuticals: ATFDs are used to dry active pharmaceutical ingredients (APIs), intermediates, and final drug products.
Food: ATFDs are used to dry food products such as dairy products, starches, and sweeteners.
Petrochemicals: ATFDs are used to dry petrochemical products such as waxes, oils, and resins.
Environmental: ATFDs are used to dry waste products such as sewage sludge and industrial waste, reducing their volume and making them easier to handle and dispose of.
Renewable energy: ATFDs are used to dry biomass, such as wood chips, to produce biofuels and other renewable energy products.

Overall, ATFDs are a versatile and reliable choice for drying heat-sensitive materials in a variety of industries. They offer a range of benefits, including high heat transfer rates, short residence times, and minimal product holdup.

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