pollution control (normally electrostatic precipitator) systems. This type of
incinerator is field erected and ranges in capacities from 150 tons/day
(136 050 kg/day) and above. Metal corrosion/erosion is a continuing technical
problem in this type of unit. The lower waterwall surfaces in particular must
be protected from the products of combustion. Such protection is required at
least up to a level where the furnace atmosphere is consistently oxidizing.
Silicon carbide refractory is generally selected as the tube protection
material because of its comparatively high heat transfer coefficient. This
permits rapid transfer of heat to the tube wall and reduces refractory surface
temperatures to minimize slagging. To minimize metal waste, use the following
Keep gas velocities low.
Use wide tube spacing.
Use silicon carbide furnace protection.
Minimize metal temperatures.
Maintain proper combustion air distribution.
Utilize an overfire air system.
Refuse Derived Fuel (RDF). Coarse RDF undergoes semi-suspension
burning on a thin fuel bed with non-agitating grates in watertube furnaces.
Fluff or double-screened RDF undergo combustion in full-suspension with
pulverized coal in Btu ratios of up to 20 percent refuse. Closer attention
must be given to the combustion compatibility and bottom ash characteristics
when firing fuels in full suspension combination fuel units (no grates for
burnout of oversize particles). Research should be conducted to determine
whether or not RDF can be produced and burned on an economical, reliable basis
before being considered a viable alternative to mass burning of unprepared
refuse. Some significant problems are involved in this alternative which
affect feasibility. These are primarily:
Economic separation of noncombustibles.
c) Material handling and storage for reliable flow of prepared
refuse to the combustion chamber.
Combustion Air Requirements. The ideal combustion air system has
no excess oxygen or unburned combustibles exiting from the furnace. Firing a
fuel with this theoretical (stoichiometric) amount of air would require