The furnace operates under controlled reducing
conditions and runs at a temperature of approximately 1600 ◦C. The
electrical power supply depends on throughput, but is usually of
the order of a few MW and is controlled independently of the other
process variables. Remote water cooled elements are deployed at
the melt line to form a protective frozen slag layer, ensuring efficient refractory performance [19]. The prepared feed ash-material
is metered at a controlled rate into the unit and the plasma power
is controlled to maintain the melt temperature at around 1500 ◦C.
The ash is rapidly melted and the molten slag phase overflows continuously from the converter after which it is granulated or cast.
The exhaust gas exiting the unit is treated in a thermal oxidiser
unit to oxidise fully any residual combustible gas species. A conventional dry or wet scrubbing system is often used to remove acid
gases contained in the off-gas prior to removal of the particulates
in a fabric filter baghouse. The cleaned gas is vented to atmosphere
in compliance with discharge consent thresholds.