Based on twin screw extruder/mixer technology

The basic concept behind the Entropic technology is a two-step process,
first converting municipal solid waste (MSW) into a low quality refuse-derived fuel (RDF). The RDF is then upgraded by continuous pyrolysis to become a granular, dry solid fuel similar to coal. The front end of the plant is similar in design to that used in today’s successful RDF plants.

Municipal solid waste first enters a large trommel screen equipped with internal spikes to open bagged waste. The primary trommel screens the solid waste through 5 inch diameter holes, with the oversized material being conveyed to a shredder for reduction to less than 2 inch top size. The shredder is located outside the main building, in a reinforced concrete enclosure equipped with pressure relief panels, vents and fire suppression.

The shredded material passes one stage of magnetic separation on its way to a Heil disc screen for size classification. Oversized material returns to the shredder while undersized material goes to air classification for separation of glass and non-ferrous metals. Undersized material passing through the first trommel also undergoes magnetic separation, followed by a second trommel screen having 1-3/8 inch holes.

The undersized material, containing dirt, glass and small combustibles, is sent to air classification. The oversized material contains aluminum cans, which are recovered by eddy current separation. The suspended materials leaving the air classifier pass a third magnetic separator on their way to RDF storage.

The heart of the Entropic process is the pyrolysis reactor, which converts the RDF into a premium coal substitute. The RDF is fed into the head end of a modified extruder/reactor and is moved continuously through the reactor by a twin screw conveyor. Mechanical energy is added to the material within the reactor, in a nearly oxygen-free environment. The waste material becomes thoroughly mixed and heated to nearly 600°F, driving off moisture and volatile matter.

The off-gases are recovered and burned to generate the mechanical energy needed to drive the pyrolysis reactor, while the remaining solids, now similar to coal, are extruded from the rear of the reactor.