A fluidized-bed-type gasification melting system not only incinerates wastes but also melts the generated ash rapidly to produce slag. The slag can be effectively reused to reinforce concrete and as an asphalt material component.
The fluidized-bed-type gasification melting furnace was developed to address diverse challenges identified in the conventional waste treatment including the following:
- Prolongation of service life for final treatment site (reclaimed land)
- Improved heat recovery
- Reduction of environment impact (decrease of dioxin level, etc.)
- Resource recycling
The fluidized-bed-type gasification melting furnace has been delivered to two facilities so far.
In this system, high-temperature treatment is conducted by making effective use of the energy obtained from the wastes. It has the following characteristics:
Energy saving and low CO2
Because slag is obtained by using energy from the wastes, the consumption of auxiliary fuel is minimal. Besides, by using carbide as an alternative to fossil fuels, CO2 emissions can be reduced.
Addresses various types of wastes
Various types of wastes can be changed into molten slag from sludge to plastic wastes thanks to the agitation effect inside the furnace.
Safe and simple
Because there is no movable mechanical component in the furnace and the gasification furnace and melting furnace are consolidated, the system is safe without the risk of gas leakage and this allows easy operation and maintenance.
A long service life of refractories is achieved by making active use of ceramic manufacturing technology.
Effective use of slag
Characteristics of water granulated slag
1. Harmful substance
1) Elution test result (mg/L)
2) Composition test result (mg/kg)
2. Physical properties
|Absolute dry density||2.87~2.89||>2.5[g / cm3]*1|
|Safety||2.2||<10[%]*1(Criteria for fine aggregate are applied)|
|Performance rate of grain diameter judgment||58.2~59.3||>55[%]*1(Criteria for fine aggregate are applied)|
|Fine powder quantity||4.8~6.2||<7[%]*1(Criteria for fine aggregate are applied)|
- *1 JIS A 5031 Standard for melt-solidified slag aggregate for concrete derived from municipal solid waste and sewage sludge or incinerated ash thereof.
- *2 JIS A 5032 Standard for melt-solidified slag aggregate for roads derived from municipal solid waste and sewage sludge or incinerated ash thereof.
The figure on the right indicates an overview of this technology.
The wastes charged into the gasification furnace are heat-decomposed in a sand layer maintained in a temperature range of 450℃ to 600℃. After the decomposition, the wastes are separated into inflammable gas (heat decomposition gas) such as CO, crushed carbon-like char and incombustibles (iron, aluminum, debris).
Heat decomposition gas and char are transferred to a melting furnace, where they are completed incinerated at high temperature in the furnace assisted by the heat of the wastes. The ash content in the char turns into slag after it is melted. The incombustibles are recovered from the bottom of the gasification furnace. They are recovered in an unoxidized form because scale is ripped off through friction with the sand. These resources are recycled.