OXIDATIVE PYROLYSIS OF MIXED SOLID-WASTES BY SAND-BED AND FREEBOARD REACTION IN A FLUIDIZED-BED

Oxidative pyrolysis of mixed solid wastes by both sand bed and freeboa rd reaction in a fluidized bed reactor was investigated. Air was the f luidizing gas (i.e. primary air, injected into the dense solids region ) and secondary gas (i.e. injected into the freeboard). The effects we re examined of (1) pyrolysis temperature (in both main and secondary c ombustion chambers) and (2) dimensionless air factor (defined as ratio of actual air how rate to stoichiometric air flow rate) on the format ion of liquid hydrocarbons (gasoline, diesel, fuel oil and residue), B TX concentration and H/C ratio of the gasoline fraction. The results i ndicated that (1) the operating temperature can be correlated with the air factor, (2) introducing air into the freeboard forms a quasi-vort exing fluidized bed similar to a cyclone freeboard capable not only of reducing sand elutriation but also of mixing the primary volatiles un iformly with the secondary air and the reactive agent, (3) a high oper ating temperature can produce lower-boiling-point oils (i.e. gasoline or diesel), a lower temperature tending to form high-molecular-weight hydrocarbons (i.e. fuel oil or heavy oil), and (4) the gasoline derive d from oxidative pyrolysis has a sulfur content ranging from 0.25 to 0 .35% wt%. Copyright (C) 1997 Elsevier Science Ltd.