Incinerators
Incineration forms an important part of a comprehensive waste management strategy. It reduces the volume of material sent to landfill, facilitates the recovery and reuse of metals and other materials, and provides heat for conversion into electricity in waste to energy plants.
All incinerators incorporate at least one chamber where the burning takes place, an air supply and flue system with treatment to minimise the release of noxious gases. Differences in incinerator design are found in the way the material to be incinerated is introduced and moves through the system. The most suitable type of incinerator depends on the composition, state and volume of the material that is to be burned.
A static hearth incinerator is commonly used for small volumes and has one opening for both insertion of waste and removal of ash. Larger volumes are more easily handled in an incinerator with movable grates which agitate the waste and keep it moving through the furnace while allowing ash and solid residues to fall below. Rollers, conveyor belts and rockers are among the many styles of moving grates.
Another solution is to move the whole chamber where the waste is burning. This is the basic premise of a rotary kiln, which consists of a refractory lined drum positioned to create a slight downward incline. Waste is introduced at the top and most burns away as it falls. An even temperature distribution is obtained by the rotation of the drum. An incinerator of this type is capable of continuous use and can be used for all household, medical and hazardous wastes in the form of solids, sludge or liquid.
A fluidised bed incinerator has no moving parts. It consists of a vertically aligned refractory lined chamber which contains a bed of small sand particles. Preheated air forced up through the bed makes the particles act like a fluid while the waste is introduced from above. This enables high combustion efficiency and lower operating temperatures. This type of incinerator is suitable for the disposal of low density homogeneous waste. It can also be used for gasification and pyrolysis.
All incinerators incorporate at least one chamber where the burning takes place, an air supply and flue system with treatment to minimise the release of noxious gases. Differences in incinerator design are found in the way the material to be incinerated is introduced and moves through the system. The most suitable type of incinerator depends on the composition, state and volume of the material that is to be burned.
A static hearth incinerator is commonly used for small volumes and has one opening for both insertion of waste and removal of ash. Larger volumes are more easily handled in an incinerator with movable grates which agitate the waste and keep it moving through the furnace while allowing ash and solid residues to fall below. Rollers, conveyor belts and rockers are among the many styles of moving grates.
Another solution is to move the whole chamber where the waste is burning. This is the basic premise of a rotary kiln, which consists of a refractory lined drum positioned to create a slight downward incline. Waste is introduced at the top and most burns away as it falls. An even temperature distribution is obtained by the rotation of the drum. An incinerator of this type is capable of continuous use and can be used for all household, medical and hazardous wastes in the form of solids, sludge or liquid.
A fluidised bed incinerator has no moving parts. It consists of a vertically aligned refractory lined chamber which contains a bed of small sand particles. Preheated air forced up through the bed makes the particles act like a fluid while the waste is introduced from above. This enables high combustion efficiency and lower operating temperatures. This type of incinerator is suitable for the disposal of low density homogeneous waste. It can also be used for gasification and pyrolysis.