Incineration (continued)

The following are types of incinerators:

Of these, rotary kiln, fluidized bed, and liquid injection are the most, prevalent in industry because of their applicability to large scale use and their versatility. Consequently, these three kinds will be emphasized.

ROTARY KILN CHARACTERISTICS:

FLUIDIZED BED CHARACTERISTICS:

LIQUID INJECTION CHARACTERISTICS:

One other characteristic that all three types of incinerators (rotary kiln, fluidized bed, and liquid injection) share is that they can all be operated in a pyrolysis or oxygen starved mode. Wastes with high caloric value that are capable of releasing great heat content are most appropriate for this kind of operation. The other types of incinerators are described as follows.

Multiple hearth incinerators consist of vertically shaped hearths, and are Primarily used for sewage sludge. They are operated from 1400-1800 ° F ( 750 - 1000 ° C ). Catalytic combustion, waste-gas flare and direct flame incinerators are all for gases. Catalytic combustors use a catalyst and are designed for low organic concentration wastes. Waste-gas flares are used for non-hazardous waste that has high organic content. Direct flame incinerators operate from 1000-1500 f and are used when waste gas contains particles.

On a final note, one very controversial form of incineration that presently has been banned in the United States, but is used in Europe is ocean incineration. For this,two incinerators are mounted on a huge ship that carries the wastes out to the middle of the ocean and burns them out there.the ideal wastes for this kind of disposal are toxic and hazardous wastes such as chlorinated matter, pcb's,and organometallics. Ocean incineration is perfect for these wastes because the acids produced can be neutralized by the huge buffering capacity of the ocean. This eliminates the need for scrubbers and other secondary treatment to detoxify the combustion products and make them more environmentally acceptable.


COMBUSTION INCINERATORS-OXYGEN USING SYSTEMS

KEY FEATURES OF A COMBUSTION INCINERATOR:


COMBUSTION STAGES


TYPES OF COMBUSTION INCINERATORS

1. MASS BURN-MOST COMMON

Minimal preprocessing required (not much sizing, shredding, etc.). Mass burn Incinerators vary in size. They range from 100 to 1000 tons of waste per day. Use a grate system to mix and agitate the waste as it travels through the Furnace to provide complete combustion. Air for combustion is supplied by fans or blowers under and over the grates.

THREE TYPES OF MASS BURN INCINERATORS (BASED ON ENERGY RECOVERY METHOD)

(A)WATER WALL FURNACE


(B)REFRACTORY FURNACE


(C)ROTARY KILN FURNACE