Hitachi Zosen plasma arc ash melting system was developed as an environmental recycle system. This system is the newest ash melting system which is able to melt by self-energy of a waste ( the generation of electricity ) in melting furnace with twin torch.

[Structure]

A municipal waste incinerator ash is supplied constantly into the melting furnace by the ash pusher. In the melting furnace which consists of a melting chamber and a secondary combustion chamber, the ash is heated and melted by twin plasma torch. A melting slag is water cooled and conveyed to a slag pit. Flue gas from the melting furnace is cooled in a gas cooler and discharged from a stack through a bag filter. Fly ash which is collected in the bag filter, is treated for immobilization of heavy metals with agent.

[Flow Diagram]

The following flow diagram is a typical case of application of Plasma Arc Type system.

[Features]

(1) Twin torch
The twin torch system does not have an electrode on the furnace bottom, which makes it easy to start the operation of furnace and avoids the problems that normally occur around the bottom electrode.

(2) Graphite torch
A graphite torch is used in a reducing atmosphere to save power consumption and to provide high heat efficiency. The graphite is automatically fed by a robot.

(3) Tilting type furnace with water-cooled jacket
A tilting type furnace body construction, with water-cooled jacket, is used to allow easy discharge of the molten metal and also to improve the durability of the heat-resistant materials and furnace body.

(4) Large secondary combustion chamber
A melting furnace, with a reducing atmosphere, and a secondary combustion chamber with sufficient volume are combined to completely burn all gases and also suppress the generation of NOx

[Capacity and Reference Plants]

(1)Capacity 
  normal range     : 20 - 100 t/24h
  maximum capacity:    250   t/24h
(2)Reference Plants