Question

Recirculatory batch dryer is a

• A. Modification of kiln dryer
• B. Deep bed dryer
• C. Continuous flow non mixing type of dryer
• D. Continuous mixing type of dryer

Hint:

Recirculatory batch dryers use continuous grain movement and mixing to achieve uniform drying, which helps prevent thermal damage to the grain.
This makes them highly suitable for processing sensitive crops like paddy.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Grain dryers are classified based on the mode of grain movement, air flow patterns, and the arrangement of the grain bed during drying.
Understanding these classifications is essential for selecting the appropriate drying system to ensure uniform moisture removal and maintain grain quality.

Step 2: Detailed Explanation:
Let us analyze the operating characteristics of a recirculatory batch dryer:
1. Working Principle: In a recirculatory batch dryer, a specific batch of grain is continuously circulated through the drying chamber.
The grain is loaded into the dryer, moves downward through the drying section where it is exposed to hot air, and is then collected at the bottom by a discharge mechanism.
A bucket elevator or screw conveyor then transports the grain back to the top of the dryer to begin another cycle.
This process continues until the entire batch reaches the desired moisture content.
2. Mixing Characteristics: As the grain is constantly discharged from the bottom, elevated to the top, and re-distributed, the individual grain kernels are thoroughly mixed throughout the drying cycle.
This continuous mechanical movement prevents the formation of localized wet or hot spots, ensuring highly uniform moisture removal across the entire batch.
3. Classification: Because the grain is in continuous motion and undergoes constant mixing during the drying operation, the recirculatory batch dryer is classified as a continuous mixing type of dryer.
In contrast, a non-mixing dryer keeps the relative positions of the grain kernels fixed during the process, which can lead to uneven drying.

Step 3: Final Answer:
A recirculatory batch dryer is classified as a continuous mixing type of dryer.