Hollow Shaft Paddle Dryer

Smart Solution for Thermal Sludge Drying

A thermal drying system using hollow rotating shafts fitted with wedge-shaped paddles to deliver uniform indirect heat transfer across sludge material — achieving high final dry solids in a compact, closed, and energy-efficient design.

How It Works

Process

Sludge is fed into an enclosed trough where hollow rotating shafts carry heat transfer fluid (steam or thermal oil) through their core and into the paddle surfaces. As the paddles rotate, they continuously mix and advance the material through the dryer while transferring heat indirectly across the large paddle surface area. Evaporated moisture is captured and exhausted through a controlled vapor outlet, maintaining a closed and odor-contained operating environment throughout the drying cycle.

Indirect Heat Transfer via Paddles

Heat transfer fluid circulates through the hollow shaft and paddle interior, heating the paddle surface which then transfers heat directly to the sludge material in contact with it no direct flame or hot air contact with product.

Continuous Mixing & Advancement

Counter-rotating shafts with interlocking paddles simultaneously mix the sludge and convey it along the trough length, ensuring every part of the material is consistently exposed to hot surfaces.

Working Principle

Temperature Regulation

Heat input is precisely controlled by adjusting the temperature and flow of the heat transfer fluid, allowing the drying profile to be tuned to the material’s thermal sensitivity and target outlet moisture.

Discharge of Dried Product

Material exits the far end of the trough at 90–95% dry solids and discharges into downstream handling, storage, or disposal systems.

Closed Vapor Management

Moisture evaporated from the sludge is drawn off through a controlled vapor outlet and directed to a condenser or scrubber, preventing odor release and maintaining a hygienic operating environment.

This Is Why

We Should Use Hollow Shaft Paddle Dryer

High Thermal Efficiency

Indirect paddle heating maximizes the ratio of heat transferred to sludge versus heat lost to surroundings, reducing energy cost per tonne of water evaporated.

Closed & Odor-Controlled

Fully enclosed design with managed vapor exhaust eliminates open odor emission — suitable for installation within plant buildings.

Compact Footprint

High heat transfer surface area packed into a small trough volume means significantly lower floor space requirement than rotary or belt dryers at equivalent throughput.