Pyrolysis (thermal decomposition) of the waste is followed by vitrification of inorganic materials at the bottom of the shaft gasifier.
The organic substances are completely decomposed into fuel gas, containing hydrogen and carbon monoxide, in a plasma decomposition reactor.
With this concept, nothing can leave the process without being exposed to high temperatures in either the vitrified slag or in the decomposition reactor.
Solid waste is fed into the shaft gasifier through a lock hopper system. Preheated or oxygen-enriched air is injected through tuyeres in the lower part of the shaft to serve as the gasification medium.
Gas and solid material move in a counter-current flow through the shaft. Non-combustible material is discharged from the shaft as liquid slag or metal about 1450°C, while the gas - including halogenated aromatic hydrocarbons - exit from the top of the gasifier at 600-800°C. The off-gas from the gasifier is mixed with plasma-heated air in the decomposition reactor where the hydrocarbons are decomposed and partially oxidized to produce a clean fuel gas at about 1200-1400°C.