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Istanbul September 2014
Optimising Alternative Fuel
Combustion and Benefits
By Constantine Manias,
FCT-Combustion Pty Ltd
INTRO
 FCT established 30 years ago to bring more science into the art of
industrial combustion. Since then it has gained a reputation for technical
excellence and introducing innovative and value adding technologies to
the cement industry and other mineral processing industries
 FCT aims to establish long term mutually beneficial relationships aimed
at delivering value to our customers
 The kiln/calciner burner systems have a major impact on the bottom line
results for a cement plant, and thus customised optimisation of the flame
for any given kiln is critical to get the best plant performance.
 FCT has core capability in cement process expertise, combustion
expertise and various types of modelling used extensively since 1984 to
optimise burner designs and deliver superior performance in FCT burners
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ALTERNATIVE FUEL AND THE CEMENT INDUSTRY

Cement Industry consumes 5% of world’s industrial power generation
and emits 5% of the world’s CO2 Emissions

The Industry needs to make amends in today’s climate of increasing
environmental concerns

Alternative Fuel usage makes sense for
 The Environment
 Community Service
 Sustainability
 Economics
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ALTERNATIVE FUEL CONSIDERATIONS
Wood Waste
Paper and Plastics

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Technical
Economic
Environmental
Product Quality
Tire Shreds
As AF is so varied, the above considerations need
to be targeted to the actual AF to be used 4
The kiln material temperature is what’s relevant…
1600
Belite
Short Flame
1500
Long flame
Temperature (C )
1400
Alite
Short strong
1300
Long strong
1200
1100
1000
0
5
10
15
20
25
30
35
40
45
50
D istance from firing end, (m)
Clinker temperatures have to be
sufficient for clinkering reactions to
occur
Furthermore, heat up and cooling rates must be
optimised for best quality clinker
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ALTERNATIVE FUEL TECHNICAL CONSIDERATIONS

Fuel Properties
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Firing Points

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Kiln Burner
Calciner burner
Riser
Environmental
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
CV
Sizing, Shape,
Burn rates
CO, NOx, Heavy Metals, Dioxins etc
Product Quality


Clinker Mineralogy, Reactivity, Grindability, Variability,
Refractory Life
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CALCINER BURNER DESIGN
 The Main Game is optimal fuel/air mixing and fuel burnout
 The calciner burner design and location along with the calciner aerodynamics and fuel properties will determine the fuel burnout and emissions
from the calciner.
 Calciner and riser duct air flow patterns tend to be very unsymmetrical and
stratified
 Generally, the lower grade alternative fuels and non-hazardous fuels should
be used in the calciner where heat transfer occurs mainly via convection
and flame temperature or length is not critical.
 There is a large often hidden cost in sub-optimal burner performance that
may be costing in production rates, fuel consumption, kiln stability,
emissions, fuel substitution levels or product quality.
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KILN BURNER DESIGN
 The Main Game is heat flux profile and fuel burnout
 The Kiln burner design along with the kiln aero-dynamics and fuel properties
will determine the heat flux profile in the kiln.
 Generally, the highest grade of alternative fuel (or hazardous fuels) should
be used at the kiln burner where it is important to maintain a hot flame
 Optimised combustion conditions and flame characteristics are important in
every cement kiln, but are even more so when alternative fuels are used.
 There is a large often hidden cost in sub-optimal burner performance that
may be costing in production rates, fuel consumption, kiln stability,
emissions, fuel substitution levels or product quality.
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FCT KILN BURNER DESIGN PROCESS


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



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
Study of kiln and process to determine burner heat liberation
Study fuel (physical & chem) characteristics for sizing of burner
Site survey to determine operating conditions and geometrical layout of cooler, kiln hood and kiln
Preliminary burner design based on the above
Physical modelling of kiln system to determine aerodynamics
Physical modelling of preliminary burner design to investigate fuel/air mixing and flame shape
CFD/Mathematical modelling of heat flux profile in kiln - need sufficient heat transfer for the
clinkering reactions but not excessive for refractories
Fine tuning of preliminary design to final design
Assessment of cooling effect on burner to prevent mechanical damage
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MODELLING IN KILN BURNER DESIGN
Water Bead modelling for aerodynamic
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MODELLING IN KILN BURNER DESIGN
Acid/Alkali modelling for fuel/air mixing
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MODELLING IN KILN BURNER DESIGN
CFD Modelling for greater detail
Biomass Kiln
Biofuel Injector & Burner Model
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Modelling Reduces Risk and provides the basis on which to
Optimise…
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Fuel Mix for AF firing
Burner position and insertion distance
Quantity of primary air required
Primary air pressure
Ratio of swirl to axial primary air
Fuel injection velocities
Burner angle in kiln
Design refractory profiles or supplementary air jets if needed to modify
kiln hood aerodynamics
Kiln Heat Flux profiles
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Refractory temperature profiles
CASE STUDY
FCT-AKCANSA CEMENT HISTORY: A partnership forged in years…
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2002 BCM Kiln 3 New Petcoke burner
2003 BCM Kiln 2 New Petcoke burner
2004 BCM Kiln 1 New Petcoke burner
2005 Re-design of Calciner/new calciner burners
2005 Canakkale Kiln 1New burner
2008 Canakkale New Kiln 2 project kiln/calciner burner systems
2013 Modification kiln 1, 2 and 3 BCM burners to fire higher rates and
different AF combinations
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AKCANSA 2002 BCM PLANT OBJECTIVES
•
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Increase use of pet-coke – limited at time to 30% at kiln burner due
to excessive build up
Reduce build up in kiln and pre-heater
Reduce CO in kiln exit gases
Improve operational stability
Improve product quality
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KEY SUCCESS FACTORS FOR PETCOKE FIRING
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Chemical balance of kiln materials (feed and fuel) to provide achievable
alkali/sulphur ratio
Correct burner design (flame shape, position and length)
Correct kiln operation (sufficient excess oxygen, acceptable kiln thermal
loading
Adequate fuel fineness for complete burn out in flame
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Original and New burner Modelled
Original Burner
New FCT Burner
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Mathematical Modelling
Kiln Wall Heat Flux
70.00
50.00
New Flame Length, m
120
Existing Flame Length, m
100
Wall Heat Flux, kcal/m2s
Actual Flame Length, m
60.00
40.00
30.00
20.00
10.00
0.00
0
10
20
30
Excess Air, %
40
50
60
80
Existing Burner
Multichannel Burner
60
40
20
0
0
10
20
30
40
50
60
70
Axial Distance from Burner Tip, m
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New BCM Kiln 3 Burner (2002)
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Results from Akcansa Kiln 3
Before
After
Max % Petcoke
30
100
Fuel Consumption, kcal/kg
865
850
excessive
No build up in 12
months
1750
Build Up
Production Rate, tpd
Clinker Quality
1650
10% increase in 28D
strength
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2013 Requirements for BCM burners
Description
Kiln 1
Kiln 2
Kiln 3
7.5
8.2
8.7
1,500
1,500
1,500
AF1 solids channel tph*
Up to 4
Up to 4
Up to 4
AF2 liquids, tph
Up to 2
Up to 2
Up to 2
AF3 solids channel tph*
Up to 3.5
Up to 3.5
Up to 6.5
Ignition channel
50mm NB
50mm NB
50mm NB
8%
8.9%
7.54%
1.65%
1.5%
1.3%
Coal/Petcoke nominal tph*
Natural Gas nominal Nm3/h* (warm-up only)
Primary Air Flow *– Total
Axial + Radial - % of stoich
RDF lofting air – 3tph - % of stoich
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2013 AF Fuel Properties
Property
Petcoke/Coal
AF1
AF2
Liquid AF
LHV kcal/kg
6800
5216
2475
9458
HHV kcal/kg
7000
5640
2610
Ash %
15.4
10.7
44.5
Moisture %
0.8
1.4
3.6
Volatiles %
20.9
80.6
50
Sulfur %
1.7
0.3
0.4
0.6
0.5
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New BCM AF Kiln Burners (2013)
After careful evaluation it was decided that the most cost effective
way to achieve the objectives was to modify existing burners.
 FCT had previously physically modelled all kilns so was familiar
with the aerodynamics in the firing zone.
 With the new fuel properties and mixes, FCT used its in-house
CFD modelling capability extensively during the re-design of
BCM burners.
 Due to the nature of the AF, FCT also offered its lofting air design
to assist in the dispersion and combustion of AF in the flame.
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Air Assisted Dispersion of RDF and other similar fuels
Lofting
Air
supply
Lofting air
solid
dispersion
pattern
RDF Pipe – easily
removable
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Lofting Air Design
RDF is in common use
fired through the kiln
burner in a separate pipe
with
air
assisted
dispersion.
FCT Optimised lofting air
design through CFD and
test firing
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Effect of lofting air on volatiles
burnout - RDF
RDF volatiles
mass fraction
(coloured regions
show RDF
concentration)
Lofting air OFF
The effect of lofting air on flame
temperature map
Flame
temperature
Lofting air OFF
Burner tip
Lofting air ON
Lofting air ON
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Effect of FCT Lofting Air
 Promotes early release and
burnout of the volatiles
 Substantially improves the char
burnout
 Alters the particle paths to stay
within the flame envelope longer
and hence produce a symmetric
flame temperature map
 Produces a more favorable kiln
wall heat flux profile
 Leads to more stable operation
and less variable product
Effect of FCT lofting air on kiln wall
heat flux profile
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2013 Modified Kiln 3 AF Burner
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CALCINER AF CASE STUDY
Objectives:
 The use of alternative fuels (spent pot liner and
liquid wastes) in the calciner was causing build
on the walls and premature refractory failure in
the calciner roof.
 The plant wanted to resolve this issue and
extend the time between stoppages
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CALCINER AF CASE STUDY
High temperature region due to coal
particles burning adjacent to this
wall – see coal particle trajectories
Bonnet
next plot.
SPL port
Fuel & air
inlets
Tertiary air
(18 kg/s)
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CALCINER PARTICLE TRACKING
Coal particles
SPL particles
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CALCINER AF FLUID PATHLINES
Tertiary air pathlines
Primary air pathlines
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CALCINER AF CASE STUDY
Co-flow config
Counter-flow Config
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CASE STUDY – STEETLEY MINERALS OBJECTIVES

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Increase use Alternative fuel
Reduce Fuel Consumption
Reduce Oxygen use
Improve Refractory Life
Reduce build up in kiln
Reduce CO in kiln exit gases
Improve operational stability
Improve product quality
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ACID/ALKALI MODELLING
Original Burner
New FCT Burner
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RESULTS FROM STEETLEY INSTALLATION 2012
% of Total Heat Input
Fuel Split
100
90
80
70
60
50
40
30
20
10
0
Solvent
Tyre
Solvent
Coal
Coal
Before
After
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RESULTS FROM STEETLEY INSTALLATION 2012
Savings
100%
90%
80%
70%
60%
50%
40%
Before
After
Clean
primary air
Before
After
Specific heat
consumption
Before
After
Industrial
oxygen use
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PRODUCT QUALITY
Product Quality may be affected by:
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Impurities present in AF that influence clinkering reactions
Variability of CV and composition of fuel
Changes to heat flux profile in kiln
Variability in fuel rates for difficult to meter fuels
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CLINKER MINERALOGY CHANGES WITH AF
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CLINKER QUALITY CHANGES WITH FLAME SHAPE
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CLINKER QUALITY
Best Option is to monitor and control Clinker
Quality On-Line with COSMA
 Direct Mineral Phase Analysis
 Continuous Real Time Analysis
 In Plant On-Stream Location
 Linked to Plant PLC
 Data Trending
 Elemental Analysis also
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CLINKER COSMA QUALITY MONITORING
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CLINKER COSMA SYSTEM
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CLINKER COSMA FREE LIME ANALYSIS
Free Lime excursions with different causes
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CLINKER COSMA
With real time clinker analysis now available, operator can:
 Control free lime better to an optimal
value
 See cause for free lime excursions
(under-burning or chemistry variations)
 Monitor the alite (C3S) and belite (C2S)
content of clinker to adjust for variations
 Monitor C3A amount and forms (cubic or
ortho-rhombic) and adjust if possible
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Istanbul September 2014
Optimising Alternative Fuel
Combustion and Benefits
By Constantine Manias,
FCT-Combustion Pty Ltd
MF3 = Petcoke + HP Biogas
MF4 = Petcoke + LP Biogas
Planar Temperature Contours (Celsius)
MF3
MF4
BG
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