INCINERATION
Define as:
Control process for burning solid, liquid and gaseous combustible
wastes to gases and residue containing non-combustible
material.
is any facility used wholly or in part for the controlled combustion of municipal wastes and other waste.
waste materials are treated at incinerator plants through the controlled application of that converts waste feed by high temperature oxidation to gaseous material.
during combustion the moisture is vapourised while the combustible waste is also vapourised and oxidised.
Objectives of thermal treatment
volume reduction
reduces 90% MSW
reduces 70% of weight
life span of a landfill could be longer
Waste stabilisation
outputs from the incinerator are ash, flue gas and combustible residue.
the output generally inert and more stable when landfill.
Sanitisation of waste
high temperature (800 – 11000C)
outlet 210 -230oC
kill all the pathogen – important in the clinical/hospital waste.
categories of incinerator
Three categories:
mass burning
Selected burning
source separated materials
The Incineration Process
Four types of incinerator
Multiple chamber incinerator
Non-heat utilization incinerator
Fluidised bed incinerator
Rotary kiln combustor
Multiple chamber incinerator
the simplest incinerator
combustion proceeds in two sage
combustion in the ignition chamber
gaseous phase combustion in the secondary combustion chamber.
Non-heat utilisation incinerator
similar with multiple chamber incinerator except the waste to energy process is not included
accommodate up to 1,000 tonnes/day.
capacity of storage pit 16 to 36 hrs of refuse intake
Fluidised bed incinerator
uses a vertical furnace as alternate design
develop and commonly used in Japan
the combustion chamber contains a fluidised bed
advantage of this system is less mechanical problems
FBI has a maximum capacity 350 tonnes/day
more efficient in burning and flue gas volume is smaller.
start up time is much smaller – 5 min
Rotary kiln combustor
rotary kiln is circular, inclined, cylindrical
slow revolving combustion chamber
waste is rotated slowly
perforation along the kiln allow O2 be pumped – efficient burning
energy transfer by three method
radiation from the refractory inner space surface transfer energy to all surface in the kiln
by convection from the hot combustion gasses to the feed material
the hot refractory surface continuously comes into contact with the underside of the bed