The single‑cylinder rotary drum dryer works by rotating the cylinder with lifting plates to throw materials, achieving drying through hot‑air convective heat exchange. It is suitable for materials such as sawdust and wood chips with inlet moisture of 30‑40%. Featuring convenient maintenance and simple operation, it performs well with messy raw materials of uneven particle sizes. However, it only reaches a thermal efficiency of 50‑60%, and suffers from a large footprint and relatively high energy consumption, so it is mostly applied in small‑and‑medium‑sized drying production lines.
The three‑pass rotary drum dryer adopts a three‑layer concentric sleeve structure for 折返 heat exchange. It can process high‑moisture sawdust and wood chips with inlet moisture between 40‑55%, and its thermal efficiency exceeds 70%. Compared with single‑cylinder equipment, it occupies only half the floor space, delivers lower comprehensive energy consumption and larger output, and is well‑suited for large‑and‑medium‑scale continuous biomass pellet production lines.
In comparison, the single‑cylinder dryer has low maintenance requirements and moderate investment, ideal for small‑to‑medium‑scale projects with low‑moisture raw materials. The three‑pass dryer stands out in energy‑saving performance and drying quality, yet it comes with higher procurement costs. Its complex sleeve structure also makes inspection and maintenance more difficult than the single‑cylinder model.
