Product Description

What is an Agitated Thin Film Dryer (ATFD)?

An Agitated Thin Film Dryer (ATFD) is a type of evaporator that dries highly viscous and heat-sensitive materials by spreading them into a thin film and agitating them on a heated surface. This method ensures efficient heat transfer and rapid evaporation of solvents or moisture, leaving behind a dry product. Various industries, such as chemical, pharmaceutical, food, and wastewater treatment, rely on ATFDs due to their ability to handle challenging drying processes with high efficiency and minimal thermal degradation.

Key Components of ATFD

Before diving into the working principle, it is essential to understand the key components of an ATFD:

1. Feed System: Introduces the liquid, slurry, or paste to the drying process.
2. Rotating Shaft with Blades or Wipers: Agitates the material, ensuring it forms a thin, even film on the heated surface.
3. Heated Surface (Jacketed Cylinder): Provides the necessary heat for evaporation.
4. Vapor Outlet: Removes the evaporated moisture or solvent.
5. Discharge System: Collects the dried product.

Working Principle of ATFD

The ATFD operates on a relatively straightforward yet highly effective principle. Here is a step-by-step breakdown of the process:

1. Feed Introduction

The feed system introduces the wet material into the ATFD. This material can be a liquid, slurry, or paste, depending on the application. Operators carefully control the feed rate to ensure consistent drying.

2. Formation of Thin Film

Once the material enters the dryer, it encounters the rotating shaft equipped with blades or wipers. These blades spread the material into a thin film across the inner surface of the heated cylinder. The thin film formation maximizes the surface area for heat transfer, facilitating rapid evaporation.

3. Agitation

The rotating blades continuously agitate the thin film, preventing it from adhering to the heated surface and promoting uniform drying. This agitation also helps break down any potential crust that may form on the surface, ensuring the entire material is evenly exposed to the heat.

4. Heat Transfer and Evaporation

The jacketed cylinder is heated using steam, hot water, or thermal oil. The heat transfers through the cylinder wall to the thin film of the material. Due to the large surface area and thin film, the moisture or solvent evaporates quickly. The vapor generated during this process exits through the vapor outlet.

5. Discharge of Dried Product

As the material moves along the heated surface, it loses its moisture content and transitions into a dry powder or granules. The blades continuously scrape off the dried product, discharging it through the bottom of the ATFD.

Advantages of ATFD

ATFDs offer several advantages that make them an ideal choice for drying challenging materials:

High Efficiency

The thin film and continuous agitation ensure efficient heat transfer and rapid evaporation, leading to high drying rates and energy savings.

Uniform Drying

Constant agitation prevents the formation of hot spots and ensures uniform drying of the material.

Handling Heat-Sensitive Materials

ATFDs can operate at low temperatures, making them suitable for drying heat-sensitive materials without causing thermal degradation.

Scalability

ATFDs are available in various sizes, making them suitable for small-scale laboratory applications and large-scale industrial processes.

Low Residence Time

The short residence time of the material in the ATFD minimizes the risk of degradation or chemical changes, preserving the quality of the dried product.