Rotary Chip Dryers

CORECO® Rotary Chip Dryers are designed for drying and de-oiling wet contaminated chips from machining operations, scrap metal, and mill scale from hot rolling operations. These dryers are designed for drying chips and mill scale containing no more than 3% combustible organic matter. Dryer capacity can be de-rated to accommodate higher combustible organic loadings if required.

CORECO® Rotary Chip Dryers are available in six standard sizes having the following capacity ranges:

Brass chips: 2,500 to 25,000 lbs/hr
Iron chips: 2,000 to 20,000 lbs/hr
Aluminum chips: 500 to 5,000 lbs/hr

The rotary retort in the CORECO® Rotary Borings Dryer is indirectly heated.  There is no direct flame impingement on the chips or extreme temperatures that could result in surface oxidation of the chips.

Functional Description of Rotary Chip Dryers

Chips from machining operations are fed into the screw feeder hopper (A). The screw feeder feeds the chips into the rotary retort (D) at a constant rate. In the rotary retort, the chips are typically heated to a setpoint temperature between 800 and 900°F to vaporize the water and oil.

Products inside the rotary retort (D) are indirectly heated. Natural gas fired burners heat the rotary retort from the outside. These burners are fired into a cavity between the outside of the rotary retort and inside of the furnace shell refractory. There is no direct flame impingement on the chips or extreme temperatures that could result in surface

Heating the borings will vaporize the water and oil found on the borings. The oxidizer fan draws room air into the discharge end of the rotary retort. This air flows through the rotary retort in the opposite direction (counter-flow) to the flow of chips. This air removes the water and oil vapors, smoke and dust particles that are generated in the rotary retort. The exhaust gases, smoke and dust particles are collected in the smoke hood (C) and exit to the pollution control system at point (B) on the smoke hood.

The smoke hood is furnished with a natural gas-fired burner to maintain the rotary retort exhaust gases at 600°F. This prevents oil vapor from condensing in the ductwork between the rotary retort and the oxidizer.

If the temperature in the rotary retort exceeds setpoint, cooling air is automatically introduced to cool the outside of the rotary retort. If an excessive amount of hydrocarbons or other combustibles are introduced with the chips into the rotary hearth, water sprays in the smoke hood are automatically initiated to quench the fire.

Dried chips exit the rotary retort (D) and enter the rotary cooling section (E), where the chips are cascaded through the induced draft, room temperature air, and exit at approximately 300-400°F.

The quality of the product produced and the actual production rate will depend on the character and quality of the contained organics and other contaminants, the particle sizes, and the uniformity at which the material is fed into the system.