Updated: July 2002
Sludge Dryer1. Sludge Dryer Outline
Sludge Dryer is applied to dry the municipal sludges from human waste, sewage or drinking water treatment plants and the industrial sludges from factories. So far, more than 1,800 units have been supplied to the customers.
Recently, there is an increasing concern for recycling of wastes. And there is worry about degradation of soil for agricultural usage resulting from using chemical fertilizers and organic fertilizers are thus being evaluated.
Under the circumstances, Sludge Dryer is employed as most-suited equipment for processing of organic sludge into fertilizers or soil rejuvenators and inorganic sludge such as metal sludge into land filling or of loadbed material or material to be re-used for the above fields.
2. Drying Process for Sludge Materials
As soon as materials to be dried are introduced into the rotating drum, they are lifted from the bottom to the top by the lifter installed in the drum and are then crushed with the blades of the disintegrator rotating at high speed as they drop down to the bottom. As this process is repeated in the vicinity of the outlet, they are effectively exposed to hot air. The resulting small lumps of material are further crushed into granules. In other words, a cascade effect occurs. A rolling granulation effect that takes place in the vicinity of the product outlet of the rotating drum by repeating the kiln action much as typical rotating drums produces particles with a nearly uniform size.
3. Features
Large heat transfer coefficient
The volumetric heat transfer coefficient is quite large and capacity per drum volume is high.
The Sludge Dryer's overall heat transfer coefficiency is 300-500 kcal m3h
This is made possible by employing a rotating disintegrator along with the drum.
High thermal efficiency and low running cost
Since the thermal efficiency is high, the dryer is economical. The material to be dried is crushed with a disintegrator and hot air contacts with large surface of dispersed sludge without short pass.
Uniform particle size of the products
A granulated product with a uniform particle size can be obtained. It is easily handled and made possible by the kiln action and disintegrator in the drum.
Little oxidation and deterioration
Since a large amount of exhaust gas circulates, the oxygen content is low and the product therefore does not readily oxidize or deteriorate.
Small exhaust gas
Since a large amount of exhaust gas is circulated to furnace, the amount of exhaust to the air is small. Therefore Sludge Dryer requires minimal auxiliary equipment such as dust collectors, deodorizer, etc. for environmental protection.
Easy operation, inspection and maintenance
The Sludge Dryer is resistant to fluctuations in the water content of the materials. The dryer does not employ complex parts so it is stable and virtually free from breakdown.
4. Structural Outline
5. Typical Applications
Sludge from sewage, human waste, drinking water treatment and food/chemical factory activated sludges.
Pulp sludge, metallic hydroxides, flue gas desulfurization sludge, etc.
6. References
Human waste and sewage treatment plants: 480 units
Drinking water purification plants: 40 units
Other industrial factories: 1,200 units
7. Specifications
Model Evaporated Model Evaporated
Volume of Volume of
Water Water
RH-12 100kg/h RH-162 1,600kg/h
RH-22 200kg/h RH-202 2,000kg/h
RH-35 350kg/h RH-252 2,500kg/h
RH-52 500kg/h RH-302 3,000kg/h
RH-77 700kg/h RH-352 3,500kg/h
RH-102 1,000kg/h RH-402 4,000kg/h
RH-137 1,300kg/h RH-502 5,000kg/h
Note: All capacities for water evaporation given in the standard specifications are for an air temperature of 800ºC, sludge water content of 83% W.B., and product water content of 30% W.B.
