Updated: July 2002

1. Outline

The ACE is equipped with an agitator (horizontally rotating arms) which incinerates both sludge and miscellaneous wastes by its rotary single-stage operation.
The special structural design causes the flames in the furnace to agitate during incineration. The complementary effect of the vortex flames and the agitation make the combustion temperature inside the furnace a nearly constant 800ºC or less. This provides excellent combustion efficiency plus energy saving. Absence of local hot spots minimizes a fear for clinkering and ensures complete combustion inside the furnace.

2. Incineration and Combustion Processes

Vaporized gas is generated from the sludge at about 200ºC in proportion to the rise in temperature of sludge introduced into the incinerator and pyrolysis gas is generated from the sludge at about 200-600ºC. These combustible gases are burnt by air blown from a perforated pipe installed on the agitating arm connected via the agitating main shaft, a hollow pipe. This is how the combustion of the gas is carried out. Their surface is constantly renewed with an agitator on the hearth rotating at several revolutions per minute. The combustible gas is generated uniformly.
Additionally, circulating gas (exhaust gas from the dryer having a high humidity 0.2-0.6 kgH2O/kgda and low oxygen content 5-18 vol%) is blown at a speed of several tens of m/s from the vortex air inlet around the incinerator walls to the inside of the incinerator so that a vortex air flow can be formed in the incinerator's combustion flame. This is why combustion of flammable gas generated from sludge becomes inactive on the surface of the ash layer and is completely burned up at the free board section (upper portion of the incinerator). Therefore, the temperature of the ash layer becomes lower than that of flame at the free board.
Solids that consist mainly of carbon generated after the gasification are exposed to air blown from the perforated pipe, while being agitated-mixed with red-hot ash of 500-900ºC as it is gradually moved toward the center of the incinerator by the state of ember combustion. Ash discharged from the ash outlet at the center of the incinerator is cooled by the conveyor with a cooling jacket.

3. Structural Outline

4. Features

- Little auxiliary fuel
This is because the temperature in the incinerator is almost uniform and combustion efficiency is high because of the vortex flame combustion. A low excess air ratio reduces the need for auxiliary fuel even more.
- Easy to operate
Skilled operation is not required because there are no complex parts.
- Complete combustion
Ignition loss of incinerated ash is exceedingly low. Since there is no clinker formation and the materials are completely incinerated, the generated ash can be reused as a roadbed material, etc.
- Small space
The incinerator requires only a small space in the facility. even when combined with a dryer, the entire system is compact.
- Direct incineration
Direct incineration of sludge is possible in case of sludge with a low water content. (If the sludge has a heating value of about 1,000 kcal/kg wet cake, it will burn by itself without the need for auxiliary fuel.)

5. Applications

- Human waste sludge and sewage sludge
- Industrial wastewater sludge
- Waste lees from industrial processes

6. References

Human waste and sewage treatment plants and other industrial factories: 170 units