Hollow Paddle Dryer for Calcium Carbonate Organic Fertilizer Animal Manure Sewage Sludge

1. Description of Calcium Carbonate Hollow Paddle Dryer

Paddle dryer consists of two rotating shafts with wedged paddles, jacketed drying chamber, drive motor and support frame. The drying process is completed in sealed drying chamber to prevent pollution by evaporated.

Paddle dryer is indirect heating drying processor. Heat medium can be steam, hot water or thermal oil which can flow through the hollow shafts and paddle via revolving joints, as well as jacketed drying chamber. Wet material is evenly fed into the drying chamber by screw feeder. With the rotation of two shafts and paddles, wet material is completely mixed and stirred to contact with the hot surface and move towards the discharge and heat transfer happens and moisture evaporates rapidly.
 

2. Features of Calcium Carbonate Hollow Paddle Dryer   

Low Operation Cost
- Easy to operate
- Requires minimal attention
- Simple instruments monitor the process
- High efficiency
- Low off-gas volume

Low Maintenance Cost
- Designed for high torque and low operating speed
- Simple durable design for easy and low maintenance
- No internal parts to adjust or maintain
- No metal to metal contact
- Shafts, pillow block bearings, and drive components are designed for long life under adverse conditions, insuring long term mechanical integrity
- Robust frame supports split pillow block bearings
- Grease-purged stuffing boxes. Alternate seal designs are available

Low Installation Cost

- Designed with compact structure
- Small off-gas system
- Vertical shaft removal reduces building size requirements
 

3. Working Principle of Calcium Carbonate Hollow Paddle Dryer

The Hollow Paddle Dryer has a metal wall which separates the process mass from the heat source (steam or hot oil). High thermal efficiency is obtained because the heat from the thermal medium goes directly into the process mass. As the material comes into contact with the heated through and agitators, the process mass is heated via conduction. With an insulated dryer, very little heat is lost. To evaporate 1kg of water only requires about 1.2kg of steam for slurry materials. Exhaust gas is minimal and at a low temperature. Therefore, the volume of non-condensable gas from the dryer, which might require treatment, is minimal.

The dryer is an indirect heat transfer device which utilizes a high degree of mechanical agitation to enhance contact with the product being dried. Evaporation rates per square foot of heat transfer surface are maximized through self-cleaning paddles and the mixing effect. Movement of the process material between the slanting surfaces of the revolving wedge-shaped paddles generates shearing forces, which clean the paddle surfaces and maximize conductivity. Counter rotating shafts move the material away from the walls, cleaning the walls by means of the tab on each paddle. This results in higher heat transfer rates than disc or single shaft designs.

The wedge-shaped paddles, and the intermeshing of the dual agitators, create a localized mixing effect around the paddle. This allows more individual particles in the bed to be exposed directly to the heat transfer surface, thereby increasing the heat transfer rate, allowing the use of smaller equipment.