Strategies for controlled MSW Incineration

1. Waste to Energy: MSW
Combustion and Dioxin
Control
Debajyoti Bose
M Tech - REE, UPES

2. ENERGY TRENDS
 Energy security, economic growth and environmental protection are the three
paramount entities for any nation
 The dwindling community of fossil fuels apart from leaving us with its
destructive cumulative effects will put an enormous strain on energy
infrastructure and life itself
 Such catastrophic outcomes require efficient and effective solutions
 Hence debates on low carbon alternatives and other energy conversion
processes are now being considered

3. THE ATOM ECONOMY
 Energy supply and waste management are great challenges that humans have
faced
 To meet these challenges we must move to an atom economy where every
atom is utilized in the best possible manner
 Waste to Energy builds the foundation for this
 To achieve this goal, a fundamental understanding of the underlying
mechanisms and processes of energy and waste generation is necessary

4. FEEDSTOCK TESTING FOR WASTE
TO ENERGY
NECESSITY:
 Testing will yield data required for combustor design
 Air pollution control system
 The waste properties will affect the air- to-fuel ratio
 The need for lime or caustic soda in the air pollution control system
 The need for pre drying if the moisture content is too high and the heating
content is too low

5. MAJOR WASTE STREAMS:
FOR MSW INCINERATORS
 MSW
 RDF
 Biomass and organic waste
 Plastics (from production waste and
mixed with other wastes)
 Bio-solids (wastewater sludge, animal
wastes)
 Liquid wastes
 Industrial and commercial wastes
 Landfill allocation and remediation
waste
 TDF
 Hazardous waste (coal tars from
manufactured gas plants)

6. ASTM COMBUSTION & THERMAL
PROPERTY TESTS
NOTE : Relevant Literature can be followed to get the rest

7. WASTE PRETREATMENT STEPS
 Basic Screening Processes:
To minimize the entry of bulky and hazardous materials onto the combustion
grates
 Pit Fluffing:
o In storage area the crane operator uses the loading claw to pick up several tons of
MSW and redistribute it across the pit
o This process has the twofold effect of breaking bags and mixing
the waste, resulting in a more homogeneous fuel, which can be fed more fluidly
into the hopper
In situations where source separation is not common practice and MSW is
disposed of in a mass burn facility, all glass, metal and non- combustibles are
passed through the moving grate furnace. The result of this is a bottom ash that
is typically disposed of in a sanitary landfill

8. SOME COMMERCIALIZED PROCESSES
OVERVIEW
BASIC:
 Fluidized bed combustion boilers
 A sulfur absorbing chemical, such as limestone or dolomite, may be
added to the bed
 Additional scrubbing equipment is necessary in waste to energy
facilities
“Municipal waste contains various constituents and impurities that induce
corrosion attacks on boiler tubing”
Table: Chemistry of common alloys used in waste to energy boilers

9. WASTE BOILERS
 Solid Waste Management
 Waste is not an ideal fuel
 Common to waste boilers is the
concept of the capacity diagram
 Determines the limits of thermal
capacity (energy input) for a
particular boiler
The Rankine Cycle

10. HEATING VALUES (FEED) CAPACITY DIAGRAM
WASTE BOILERS (CONTINUED)
Source: ECN, 2012; Patel et al. , 2001; Vølund, 2009

11. ENERGY RECOVERY & DISTRICT
HEATING
When a WTE facility has access to a large district heating network, such as in
some cold weather countries like Denmark, Sweden and Finland, it is common to
establish back- pressure turbines, where all the steam exiting the turbine
is used to produce district heat

12. OPTIMIZING WTE FACILITIES
Boiler efficiency (generating more steam):
 Lowering the excess air ratio and lowering the flue- gas temperature will
lower the resulting thermal loss to the chimney, and hence produce more
steam
Water steam cycle optimizations:
 Using feed water and condensate preheaters, as well as preheating the
combustion air, can increase the thermal cycle efficiency
Turbine back-pressure:
 Besides the live steam temperature, the turbine back- pressure can be
decreased, for instance by having larger condensers

13. AIR CLEANING EQUIPMENTS
 Cyclone Separator
Scrubbing Systems (Wet & Dry)
Electrostatic Precipitator
Bag Filters

14. THE SEVESO ACCIDENT
 In 1976 di-benzo-p-dioxins (PCDDs) and di-benzo-furans (PCDFs) in filter ashes
from three Dutch municipal solid waste combustors were detected
 Initiated violent public discussions concerning waste combustion, especially in
Europe
 Initiated extensive R&D activities to understand the formation of these
compounds and to develop countermeasures
 Triggered the waste authorities to issue tighter legislative regulation of air
emissions
“This was a strong driver for the development of improved
technology”

15. DIOXINS
 The group of 75 polychlorinated di-benzo-p-dioxins and 135 di-benzo-furans
 A group of some (but not all) highly toxic compounds
 Olie, Vermeulen and Hutzinger were the first to report on the dioxins found in
filter ashes from three Dutch municipal solid waste combustors (Olieet
al.,1977)
Mass flow of dioxins in a
waste combustor in the early
1980s

16. ABOUT DIOXINS & FURANS
 Are formed when two six carbon benzene rings are joined by
two oxygen atoms
 Significant exposure to dioxin like compounds can result in the acute
disfiguring condition known as “chloracne”
 Medical follow ups on people exposed have not resulted in definitive links to
an increased incidence of cancer
 The molecular structure of these chlorinated compounds has the geometric
configuration to damage DNA
 These compounds are currently listed by the World Health Organization as
probable carcinogens

17. DETAILED INVESTIGATION OF THE
REACTION MECHANISM
 Stieglitz and Vogg,1987; Hagenmaier et al. , 1987; Hiraoka et al. , 1987; Vogg et
al. , 1987; Gullet et al. , 1990 all concluded that:
The ingredients and conditions necessary to form dioxins are:
 Products of incomplete combustion (PICs), e.g. soot
 Halides, mainly chlorides, but also bromides
 An oxidizing atmosphere
 A catalyst – copper salts being most effective.
“This slow reaction is called de novo synthesis and mainly takes place in the dust
deposits in the backend of the boiler and, if the dust removal system is operated at
temperatures above 200°C”

18. OBSERVATIONS MADE
 Careful investigations in test plants carried out by Hunsinger et al., 2002
confirmed that dioxins fed into the combustor along with the waste are
totally destroyed inside the combustion chamber
 The dioxins found in the flue gas were newly synthesized in the boiler
“On the basis of this knowledge, strategies were soon developed to minimize
their formation by suitable measures”

19. CONSIDERATIONS
Vogg et al., 1991 suggested the following counter measures:
 Optimization of combustion control to achieve a better burn out and hence to
reduce the content of PICs in the raw gas, in the fly ashes and in the deposits
inside the boiler
 Reduction of the gas velocity in the fuel bed to minimize the release of fly ash
 Adequate cleaning of the boiler to minimize the deposition of fly ash
 Operation of the dust removal system at low temperature
“Reeck et. al, 1991 reported that it was possible in most existing plants in
Germany, without major upgrades, to reduce dioxin emissions easily, quickly and
without additional costs in the order of around 1–5 ng (I-TE)/m³ “

20. INTERNATIONAL STANDARD
 International dioxin emission limits is of the order of 0.1–0.3 ng(I-TE)/m³
 Secondary abatement measures are needed
Dannecker and Hemschemeier, 1990 suggested that it needed to be removed
by additional process stages like adsorption on charcoal fixed- bed filters
Hiraoka et al., 1989 suggested that catalysts if operated in oxidative mode, can
have a high destruction potential for dioxins

21. DRY SCRUBBING WET SCRUBBING
SCRUBBING SYSTEMS
 The REMEDIA® process
 Uses a device in dry scrubbing
systems
 Bonte et al., 2002 claimed by
incorporating a low
temperature catalyst in the
cloth of the filter, it can be used
to eliminate gaseous organic
compounds
 Operates between 140-260°C
 Medical and MSW plants in
Europe & Japan use this
 Carbon-filled plastic material
called Adiox® has been
developed
 Andersson et al., 2003
showed that it can be used a
s tower packing & demisters
 The plastic absorbs dioxins
and other low volatile organic
pollutants
 The dioxin loaded packing
can be burnt in the plant’s
furnace to destroy the dioxins
totally
 Thermal treatment plants

22. Vehlow, 2005 showed that the emission of dioxins from state- of-the- art
plants is in most cases well below 0.01 ng(I-TE)/m³ in Europe

23. Concentrations of PCDD/F in bottom ashes from grate furnaces; the shaded area
indicates typical concentration ranges in natural soil in Central Europe (adapted from
Vehlow et al. , 2006)

24. WTE BENEFITS
 Output can be heat, electricity and CHP
 Efficient way to reduce waste volume
Outputs State Quantity by wt
of Original Wt
Comment
Incinerator bottom
ash
Solid residue 20-30% Potential use as aggregate
replacement or non biodegradable,
non hazardous waste for disposal
Metals (Ferrous and
Non Ferrous)
Requires
separation from
MSW or IBA
2-5% Solid for re-smelting
APC residues (including fly
ash, reagents and waste
water)
Solid
residue/liquid
2-6% Hazardous waste for disposal
Emission to
atmosphere
Gaseous 70-75% Cleaned combustion product

25. LIMITATIONS TO WTE
 Heavy investment and high operating cost
 Waste incineration is applicable if certain requirements are met.
 The composition of waste in developing countries is questionable and its
suitability for auto combustion
 Plant requires skilled staff
 Well maintained landfill for ash disposal

26. OVERVIEW: ENDING REMARK
 Waste combustion is a key component in waste management strategies
 An efficient and reliable process for inertizing that fraction of residential
waste that is left over after material recycling
 The technology is well developed and different processes can be applied
according to local conditions
 The control of dioxins has been developed to a degree that the air
emissions as well as the concentrations in bottom ash cause no harm
 Emissions now are very low and have no discernible impact on human
health and the environment

27. REFERENCES
 STM Test Methods , American Society of Testing and Materials, 100 Barr Harbor Drive,West
Conshohocken, PA, www.astm.org/DIGITAL_LIBRARY/index.shtml. 2009.
 North American Combustion Handbook , Volume I third ed, 1986, Volume II third ed, 1997, North
American Manufacturing Company, Division of Fives, Cleveland, Ohio, www.namfg.com/comb-
handbook/gra49.pdf.
 Perry’s Chemical Engineers’ Handbook (8th Edition), 2008, McGraw-Hill, NY.
 Steam, Its Generation and Use , Babcock & Wilcox, 41st ed., Barberton, Ohio, shop.
fullpond.com/bwco/pdf/STEAM41orderform.pdf.
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prior to landfi lling: Study of biological treatment of size reduced MSW without
mechanical sorting ,Waste Management 27 , 1755 – 1764.

28. REFERENCES
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 Stoller , P and Niessen , W ( 2009 ), Lessons learned from the 1970s experiments in solid waste
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29. REFERENCES
 Patel N , Gordon G , Howlett L , 2001 , Accomplishments from IEA Bioenergy Task 23: Energy
from Thermal Conversion of MSW and RDF
 Vølund , 2009 , 21st century advanced concept for waste-fi red power plants , Babcock & Wilcox
 Andersson S , Kreisz S and Hunsinger H ( 2003 ) Innovative material technology removes dioxins
from fl ue gases ,Filtration and Separation , 40 , 22 – 25
 Bonte J L , Fritsky K J , Plinke M A and Wilken M ( 2002 ) Catalytic destruction of PCDD/F in a
fabric fi lter: Experience at a municipal waste incinerator in Belgium ,Waste Management , 22,
421 – 426.
 Dannecker W and Hemschemeier H ( 1990 ) Level of activated- coke technology for fl ue gas
dust collection behind refuse destruction plants looking at the problem from the special
aspects of dioxin separation ,Organohalogen Compounds , 4 , 267 – 272

30. THANK YOU !!!
A PRESENTATION BY
DEBAJYOTI BOSE
M TECH REE, UPES
INTERN AT ABELLON CLEANENERGY