An incinerator is a unit designed for burning dry or wet waste solids. Incinerators range from small domestic units, suitable for burning only the drier wastes, to large multiple-chamber municipal installations that can bum every type of combustible material.
Incinerators are usually operated so that the combustion gases are raised to a minimum temperature of about 1300° F (700°C). Combustion of the waste material alone may supply enough heat to maintain the proper combustion temperature, or an excess of heat. Additional heat, if necessary, can be supplied by a gas or oil burner. Waste material generally ranges from that with a water content of 10% to 25% and a heating value of approximately 6,500 Btu per pound (3,500 cal per gram) to that having up to 85% water and a heating value of about 1,000 Btu per pound (550 cal per gram). The wetter wastes require supplementary heating.
A typical large incinerator unit has a continuous feed of raw refuse into a precombus'tion chamber, where preliminary drying and initial combustion take place. The partly burned material then drops onto a continuously moving grate that carries it to the major combustion chamber to be consumed. The gases from the precombustion chamber pass over the main bum-ing area, where odorous gases are burned while the combustion of the combustible solids is completed. The particulate matter carried over in the flue gases is caught by a dust collector or precipitator. Unburned refuse leaves the combustion grate to cool before being taken to a fill area. Large amounts of energy can be produced in an incinerator of this type, and frequently this energy is used in a boiler system to generate steam for heating or producing power.
Smaller incinerators, such as those used in many apartment buildings, usually have only one combustion chamber, and refuse is dropped directly into the furnace, often from chutes.