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Desmond Tan

on 16 October 2014

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Transcript of Incineration

Lim Zhi Rui
up until 1900
1990 onwards
Group Members: Desmond Tan
Tan Zhe Xuan
Eng Zi Qi
Lim Zhi Rui
Goh Jian Hong

What is incineration?

Incineration is the art of completely combusting waste, while
maintaining or reducing emission levels
below current emission standards and , when possible,
recovering energy
, as well as
eventual combustion residues (solid and gaseous products)

Volume reduction
Energy recovery

O&M $
Energy recovery is limited
Pollutant generation
Desmond Tan
Desmond Tan
3 types of thermal processing systems
Desmond Tan
What is pyrolysis?
Thermochemical decomposition of waste, normally organics in the absence of oxygen at high temperature
`Products of pyrolysis:

Pyrolysis gas (gaseous) - methane, hudrocarbons carobn dioxide etc. ,

liquids (condensables) - dissolved organic compounds, tars and higher hydrocarbons

char (solid) - carbon, ash, other impurities like silica
What is gasification?
Partial combustion conducted with a deficiency of air
Products of gasification : Mainly flammable gas which can be used for electricity production
The burning of waste materials in excess air, often resulting in fully oxidized products
Two types of combustion systems:


Desmond Tan
Desmond Tan
Mass-fired System
Mass-Fired Systems
Consists of several types - continuous-feed, hopper and gravity chute systems etc.
Desmond Tan
Continuous-feed system
Hopper and chute system
Waste after recovery is fed directly into the mass-fired burner - heterogeneous
Refuse-Derived Fuel-Fired
RDF: Segregated high calorific fraction of processed MSW (homogeneous)
RDF Fluidized
Bed Combustor
Desmond Tan
Dioxins & Furans
Endocrine disrupting
How can dioxins and furans be reduced?
Combustion at higher temperature (destroy dioxins and furans, their pre-cursors)
Increase residence time of combustion process
Rapid cooling
High supply of oxygen
Good mixing (turbulence)
Zhe Xuan
Catalyzed by certain heavy metals (e.g Cu, Fe, Zn)
Organic matter + Chlorine
Optimal rate between 200'C - 450'C (up till 800'C)
A very, very brief history
Reduce formation
Population - 5.3 million
Land Area - 730 Square Kilometers
Waste Collection
Privatized since 2001
End Products of Incineration
Scrap Metal
Thorough mixing of
Mixes and distributes the combustibles
Bottom Ash
962 million kWh - 2 to 3% of SIngapore's electricity
8 - 15% of bottom ash
Magnetic Seperators remove ferrous pieces
Sold to local steel mill
New Metal Recovery Facility by 2014
Flue gas
(CO2, SO2 etc)
Advanced Air Pollution Control Equipment
Air gaps for combustion air feed
Combustion Issues (fly ash flue gas)
Complete combustion
Incomplete combustion
Mineral acids (e.g. HCl)
SOx (sulfur oxides)
Thermal NOx (> 1500'C)
heavy metals (aerosol)
dioxins and furans
Waste streams of interest
CO (carbon monoxide)
POM (e.g. PAHs, PCBs)
heavy metals (aerosol)
dioxins and furans
Increased greenhouse gas
Incineration 'holds back'
Green waste: wood waste, branches
Sewage sludge: Reduce volume, stabilize and sterilise
Electrostatic Precipitator (ESP)
Hazardous waste: Examples are used oils or solvents
Common pollutant control systems (flue gas)
Non-recyclables of MSW
Wet Scrubber
decrease visibility
acid rain
lung irritation
cause corrosion
pre-cursor for ozone production
lung irritation
cause corrosion
remove dust particles by capturing them in liquid droplets
using scrubbing fluid (e.g CaCO3 for SO2 removal or H2O2 for NOx removal)
Bottom Ash
Fly Ash
ash that falls from the grate
fine ash that becomes airborne
Bottom Ash
inert materials & metals
usually contain high amount of Si and Al
may even disposed into landfill directly
Why Wet Scrubber?
can remove both particulate matters and gas pollutants
good liquid-to-gas contact enables efficient removal
small size
can handle high temperature
Why is it not that common?
Collected fluid can be corrosive (acidic)
Disposal of collected fluid
Requires specific scrubbing fluid to remove specific pollutant
Difficult to recover scrubbing fluid
High operating cost required
Removal of pollutant via electrostatic charge
Voltage given in wires (in between 2 plates)
Drive flue gas particles to the plates
Vibration on the plates to settle and collect
Removal of flue gas by channeling into bags
Bags as filter media
Removal depends on the pore size
Regular removal is required to prevent fouling
Dry Lime Reactors
Electrostatic Precipitators
Catalytic Bag Filters
Sent to Tuas Marine Transfer Station
Tuas Marine Transfer Station
Semakau Landfill
Intermediate Collection Point
In 2011, received 1500 tons/day bottom ash
Could rise to 2100 tons by 2023
Jalan Buroh
150m long
In used since 2002
Groundwater/surface monitoring tests are safe
Tampines Road
Incineration Plants
Waste-to-energy (WTE)
Senoko WTE Incineration Plant
Keppel Seghers Tuas WTE Plant
Tuas South WTE Plant
Tuas WTE Incineration Plant
Ulu Pandan WTE Incineration plant
Opened in 1979
Singapore's 1st
Largest of its kind in SEA
Decommissioned in August 2009
Waste disposed of in landfills before 1979
New plant - 2018
Increase in demand for incineration
zhe xuan
zhe xuan
zhe xuan
zhe xuan
zhe xuan
Post-combustion Processes
material recovery
ferrous metal extraction
can be used for roadbeds, earthworks, building materials
quenching or cooling using water
lock toxic metals into glass matrix (vitrification)
transportation -> storage/landfill
Bottom Ash
(+) as efficient as ESP
(-) highly combustible
(-) sensitive to corrosion and moisture
Countries that
imports waste?
Waste Statistics
Around 50% of household waste is sent to waste-to-energy plants

Only 4% of the nation's waste ends up in landfills

Generates 20% of their district heating

Provides electricity for a quarter of a million homes

Due to successful waste management plans, Sweden does not have enough waste to incinerate

Amount of waste generated also decreased due to economic downturn
Imports 800,000 tonnes of waste every year from other European countries
Why it works?
Incineration is cheaper in Sweden than Norway

Sweden is paid to incinerate the waste

Sweden gets electricity and heat from burning waste instead of fossil fuels

Ashes are then transported back to the Norway to be landfilled
Is recycling rate being compromised?
What about emission levels?
Goh Jian Hong
Goh Jian Hong
Goh Jian Hong
Goh Jian Hong
Goh Jian Hong
Goh Jian Hong
Goh Jian Hong
Goh Jian Hong
In summary...
Any questions?
Veolia ES
800 Super
1500 tons used
Bottom ash needs to be stabilized first
4 operational
energy and cost efficient
very high removal efficiency
can handle acidic particles or droplets
Eng Zi Qi
Eng Zi Qi
Eng Zi Qi
Eng Zi Qi
Eng Zi Qi
Eng Zi Qi
Eng Zi Qi
Eng Zi Qi
Eng Zi Qi
zhe xuan
zhe xuan
Lim Zhi Rui
Lim Zhi Rui
Importing Waste?
Goh Jian Hong
Emerging trend in several European countries
Other Factors
Countries need to comply with tougher EU landfill directives

Lessen the greenhouse impact
"If you incinerate one tonne of Italian waste in Sweden you get 500 kg CO2 equivalent less emissions than if it is dumped in a landfill in Italy"
Goh Jian Hong
Goh Jian Hong
Desmond Tan
Full transcript