Counter-flow dryer drums are so named because the aggregate entry point is opposite the combustion end of the dryer drum.

• A. True
• B. False
• C. Not true
• D. Cannot be determined

Answer: (A)

In a counter-flow dryer, hot gases and the aggregate move in opposite directions. The burner end heats the gases that travel toward the far end, while the aggregate is fed in at the opposite end and moves toward the burner side. This opposing flow is what the term “counter-flow” describes, so the aggregate entry point being opposite the combustion end is correct. In contrast, a parallel-flow dryer would have the aggregate and gases moving in the same direction.