Updated: July 2002

1. Outline of Equipment

Ebara's fluidized bed incinerator technology has a long history. The company delivered its first fluidized bed incinerator for sludge treatment in 1975, and its first incinerator for municipal waste treatment in 1977.
Since then Ebara Corporation has developed and installed over 190 revolving flow type fluidized bed incinerators that need no pretreatment systems. The technology and experience during this period have been highly praised, and the company has received many awards such as a prize from the Japan Mechanical Engineering Society in 1984, the 19th prize from the Mechanical Engineering Promotion Association, the 27th prize from the Director General of the Science and Technology Agency, and the Imperial Award from the Japan Invention Academy in 1990. The revolving flow type fluidized bed incinerator for sludge incineration built with Ebara's rich experience generates internal circulation flows within a fluidizing media, and provides a number of features which are not found in conventional bubbling type fluidized bed incinerators, that mainly depend on vertical movements.

2. Features

The circulating flow type fluidized bed incinerator provides the following features by generating internal circulation flows within a fluidizing bed.
1) Effective diffusion of sludge
->The sludge inlet can be reduced, simplifying supply facilities.
2) High combustion efficiency in the incinerator bed
->The incinerator can be loaded heavily, saving auxiliary fuel.
->The incinerator can be made more compact.
3) Outlet at bottom of incinerator
Non-combusted substances contained in combustibles can easily be discharged. This enables mixed combustion of wastes from screenings and grit.
4) Flow in all directions inside incinerator bed
->The temperature distribution in the flowing layer is made more even, resulting in stable incineration. There is no risk of clinker generation due to local heat build-up.

3. Performance

The inside of the incinerator comprises the fluidizing bed and the free board. Incineration takes place at a high temperature (about 850ºC) within a short period of time to treat dehydrated cake and reduce its weight in a hygienic manner.
In the fluid bed, the circulation air speed of such that the central area moves slowly and the surrounding area reaches higher speed. In other words, the center is a weak moving bed, and the surrounding part is a strong flowing bed. Additionally, the upper part of the incinerator is equipped with a throttle (deflector). In this arrangement, the fluidizing media (silica sand) create strong internal circulation flows in all directions from the incinerator center, even without mechanical movable parts in the incinerator.
In the free board, non-combusted gas burns fully and the exhaust gas is discharged from the top of the incinerator.

4. Areas of Application

1) Objects to be incinerated: Biologically treated sludge cake.
2) Moisture content: less than 85%
3) Plant size: 5 to 300 dry tons cake/day
4) Mixed incineration of wastes from screenings and grit possible.