Rotary Dryers for Sawdust and Biomass

Operating Rules

The wet material, through a feeding device consisting of a screw system, enters the drying drum, where the drying process of the material takes place. The rotary motion of the drum causes the spreading of the dry material inside the drum and its alignment towards the exit opening. The loss of moisture from the raw material follows through direct contact of the dry material with the hot air mixture of combustion gases.

Due to the spiral-shaped structure of the drum and the drying factor produced by the main fan of the dryer, the dry material is detached from the drum and falls into the discharge chamber, where it settles after slowing down.

Using the extraction screw, depending on its destination, it is transported either outside or to the grinding unit, where it is further processed into the desired fractions. After removing fine particles, the hot drying air together with steam is discharged into the atmosphere through the main cyclone and the dryer’s stack.

The dry material falls to the conical part of the cyclone, from where it is transported to the grinding unit. Material that does not need to be ground goes directly outside the cyclone.

Advantages of the dryer:

• The installation is constructed in 4 mono-blocks: sawdust feeder – burner – dryer – cyclone, making it easy to install and dismantle without foundation problems.
• High thermal efficiency due to relatively high working temperature at the inlet and very low at the outlet.
• Low installed power due to well-calculated and optimized aero-thermal circuits.
• Long operating life due to robustness and the materials used.
• Versatility of the dryer, capable of drying various industrial and agricultural products.
• Very rapid installation, requiring the connection of several blocks. With suitable lifting equipment, the installation can be assembled in 3-6 days.
• The connection between the burner and the dryer is made with a high-temperature metal duct, thermally insulated.

CONTROL: The system is controlled by a control panel containing top-quality equipment. The instruments are electronic and monitor both the inlet and outlet temperatures. Digital sensors are mounted in the panel.

THE SYSTEM CONSISTS OF: The dryer drum with three concentric passes, mixing and material advance paddles, made of steel sheet, inspection doors, and seals.

• 2 rotating rings with toothed crown.
• 4 drum support rollers, ball-bearing supports, steel treated rollers.
• Drive reducer with pinion and chain, electric motor.

Centrifugal fan with special construction, belt transmission, adjustable damper, electric motor.

Cyclone for collecting the dried product, made of galvanized steel with a rotary valve of 1.5 kW.

Boiler for producing the hot air required for the drying process – equipped with a feeding screw, constructed from steel with a base covered with refractory cement, central burner made of refractory steel, a thick-walled refractory steel combustion chamber, and an oxygenation fan.

• ACOF burner with a progressive pitch feeding screw made of cast iron, primary air fan with adjustable damper.
• Sawdust loading device into the dryer with a cylindrical chute lined with refractory material, driven by an electric motor.
• Mounting frame made of steel frames.

Hopper with a screw for feeding dry material to the boiler.

2 electronic thermometers with electrical contacts, one mounted at the inlet of the air and the other at the outlet, electric safety thermostat.

Fire safety device with solenoid valve and water spray.

Control system consisting of an electric control panel with top-brand equipment, PLC WITH DISPLAY PANEL, main switch, motor thermal protections, internal connection instruments according to regulations.

Depending on the temperature at the drum’s outlet, the temperature in the burner’s feed screw is controlled. The temperature at the drum’s outlet is correlated with the moisture coefficient of the dry product. Temperature regulation is automatically performed using an intelligent temperature controller. The temperature at the drum’s outlet can be monitored on the touchscreen display graph.