8/10/2019 Calciner Technology in AF Firing
1/22
Calciner Technology for improved alternative
fuel firing
8/10/2019 Calciner Technology in AF Firing
2/22
Calciner Presentation Agenda
Comparison of several HeidelbergCement calciners which
are firing high percentage of calciner alternative fuels
Desirable features which maximize the ability of burning
alternative fuels in the calciner
Conclusion
8/10/2019 Calciner Technology in AF Firing
3/22
Comparison of several HeidelbergCement calciners which are
firing high percentage of calciner alternative fuels
Antoing (CLE Onoda type calciner)
Slite (CLE Onoda type calciner)
Brevik (KHD Low Nox calciner)
Important features and principles for enhancing secondary
fuel firing in a calciner
1. Gas retention time
2. Geometry: particle retention time gas mixing
3. Hot core combustion
4. Kiln riser restrictor5. Chlorine bypass system
6. Pressure drop across calciner system
8/10/2019 Calciner Technology in AF Firing
4/22
8/10/2019 Calciner Technology in AF Firing
5/22
Geometry of Antoing Calciner (CLE Onoda type)
A
B
C
D
E
F
G
Preheatedmeal
Tertiary air
Tertiary air Tertiary air
Petcoke Waste fuel
Preheated meal
To lowercyclone stage
Kiln gas
MIXINGCHAMBER
SWIRL
CALCINER
LOOPDUCT
Calciner downcomer
Inclined Duct
8/10/2019 Calciner Technology in AF Firing
6/22
Geometry of Slite Calciner (CLE Onoda type)
Tertiaryair
Tertiary
air
Calciner
coal
Shredded
car tyres
Preheated
meal
Bypass
gas
Kiln gas
To lower
cyclone stage
Diaphragm
8
97
11
1
5
6
13
Mixing ChamberInclined Duct
8/10/2019 Calciner Technology in AF Firing
7/22
Samples and measurements Brevik
(KHD Low-NOx calciner)
To lower
cyclone
stage,
string 1
To lowercyclone
stage,
string 2
Preheated
meal,
string 1
Preheated
meal,
string 2
Solid
hazardous
wasteSecondary
coal
Tertiary airKiln
gas
A
F
K
M
8
13
X5
X10
Loop Duct
Inclined Duct
Square Duct to Circular
Transition
8/10/2019 Calciner Technology in AF Firing
8/22
1. Residence time in investigated AS calciners of HeidelbergCement
(note retention times calculated on a common set of data)
The calculated residence times are from the calciner fuel inlet to thelower cyclone stage. Residence times calculated using a common set of data
Avg = 3.6 seconds
Max = 6.4 seconds (Edmonton)
Min = 1.9 seconds (Canakkale)
Union Bridge = 6 seconds @ 5500 MTPDclk and 5 seconds at 6500 MTPDclkPadeswood and Lixhe similar to UB
Plant Calculated gasresidence time
[s]
Antoing 2.9Brevik 3.5
Bykcekmece 3.7
Canakkale 1.9
Edmonton 6.4
Kjoepsvik 3.3
Mason City 3.1Slite 3.7
Tehachapi 4.4
Vac 3.2
This data along with
following table makesclear that retention time
isnt the only pre-
requisite for burning
secondary alternative
fuels
8/10/2019 Calciner Technology in AF Firing
9/22
Calciner Testing Data
Antoing Slite Brevik
Calculated gas retention
time seconds 2,9 3,7 3,5
CO concentration -
bottom cyclone exit ppmv ol 130 700 1000Oxygen concentration -
bottom cyclone exit %v ol 3,8 4,6 3,5
Temperature - bottom
cyclone exit C 964 895 890
Antoing
Bottom CycloneConditions
1100 ppmvol CO
130 ppmvol CO
Calculated gas retention time for bottom
Cyclone is 0,75 seconds assuming that
50% of the cyclone body is active. This means
that the required gas retention time for fuel burnout
is at least 3,7 seconds with good calcinergeometry (as will be discussed in the next
section). It is therefore recommended to have as a
minimum about 3 seconds to top of loop duct, then
deflection chamber, then 1 2 seconds gas
retention time before entering bottom cyclone
Antoing Data
8/10/2019 Calciner Technology in AF Firing
10/22
2. Good calciner geometry: higher particle retention time and gas mixing
To lower
cyclonestage,
string 1
To lower
cyclone
stage,string 2
Preheated
meal,
string 1
Preheated
meal,string 2
Solid
hazardous
wasteSecondary
coal
Tertiary airKiln
gas
A
F
K
M
8
13
X5
X10
Tube type calciner Not a
good design for increasing
particle retention time and gas
mixing
Calciner design which enhances
particle retention time and gasmixing
Turbulant flow increasesmixing which is generated
by the geometric design
and the way the various
flows are introduced intothe calciner. Low
velocities and turbulance
increase particle retention
time
Brevik - When
RDF and SHW
are supplied at >
40% of calcinerfuel, CO in main
stack gases goes
high (> 0,3% CO)
Geometry of the Antoing calciner system is good to promote
8/10/2019 Calciner Technology in AF Firing
11/22
Geometry of the Antoing calciner system is good to promote
gas mixing, turbulance and particle retention time
A
B
C
D
E
F
G
Preheated
mealQuaternary air
Tertiary air Tertiary air
Petcoke Waste fuel
Preheated meal
To lowercyclone stage
Kiln gas
MIXINGCHAMBER
SWIRL
CALCINER
LOOPDUCT
Calciner downcomer
Inclined Duct
8/10/2019 Calciner Technology in AF Firing
12/22
Interesting to compare geometry and gas velocities
of both Antoing and Slite
Preheatedmeal
Quaternary air
Tertiary air Tertiary air
Petcoke Waste fuel
Preheated meal
To lowercyclone stage
Kiln gas
MIXING
CHAMBER
SWIRLCALCINER
LOOP
DUCT
Tertiaryair
Quaternaryair
Secondarycoal
Shreddedcar tyres
Preheated
meal
Bypassgas
Kiln gas
To lowercyclone stage
Diaphragm
11 m/s
15 m/s
29 m/s
13 m/s
25 m/s
Retention time = 2,9 sec.
Average Velocity = 17 m/sec
12 m/s
25 m/s
14 m/s
12 m/s
Retention time = 3,7 sec.Ave. Velocity = 10 m/sec
8/10/2019 Calciner Technology in AF Firing
13/22
8/10/2019 Calciner Technology in AF Firing
14/22
Union Bridge design based on computer modeling and
pilot plant testing
Deflection Chamber
Deflection chamber
Inlet Duct
Deflection Chamber
Outlet Duct
Feed Pipe
Deflection Chamber Model
CO Injection
Manual CO
Measuring Ports
Mixing efficiency, build up and plugging tendencies are
important topics
8/10/2019 Calciner Technology in AF Firing
15/22
3. Hot core - promotes combustion with a flame and reduces
tendency of flameless combustion or delayed combustion
8/10/2019 Calciner Technology in AF Firing
16/22
Both Slite and Antoing are feeding alternative fuels to the hot core in
the combustion hat of the swirl calciner
A
B
C
D
E
F
G
Preheated
mealQuaternary air
Tertiary air Tertiary air
Petcoke Waste fuel
Preheated meal
To lower
cyclone stage
Kiln gas
MIXING
CHAMBER
SWIRL
CALCINER
LOOP
DUCT
Tertiary
air
Quaternary
air
Secondary
coal
Shredded
car tyres
Preheated
meal
Bypass
gas
Kiln gas
To lower
cyclone stage
Diaphragm
8
97
11
1
5
6
13
4. Kiln riser restriction - (high riser duct velocity) important to
8/10/2019 Calciner Technology in AF Firing
17/22
4. Kiln riser restriction (high riser duct velocity) important to
assure solid alternative fuels do not fall into the kiln and burn in
the feed bed of the kiln leading to increase in volatile cycles.
Tertiary
air
Quaternary
air
Secondary
coal
Shredded
car tyres
Preheatedmeal
Bypass
gas
Kiln gas
To lower
cyclone stage
Diaphragm
8
97
11
1
5
6
13
28 32 m/sec Good design number
Slite gas velocity is about 40 m/sec, but the pressure drop
is also high. Pressure measured above the restriction is >
15 mbar, during tire firing.
8/10/2019 Calciner Technology in AF Firing
18/22
5. Chlorine bypass system
Alternative fuels are typically high in chlorine.
Animal meal 0,7 1,0 % Cl
Plastics 1,0 % ClRefuse derived fuel 0,5 2,0 % Cl
Resofuel (impregnated saw dust) 0,3 % Cl
Solid hazardous waste 0,5 % Cl
Small chlorine bypass systems significantly increase the
ability of a kiln system to utilize alternative fuels. Slite and
Antoing operating with about 6% kiln bypass.
8/10/2019 Calciner Technology in AF Firing
19/22
6. Calciner system pressure drop
Pressure drop across different calciner systems are in
general in the range of 8 15 mbar (~80 150 mmwg)
verified by a pressure drop across Antoing calciner of
about 11 mbar (110 mmwg).
8/10/2019 Calciner Technology in AF Firing
20/22
Conclusions
CLE-Onoda type SLC-S calciner promotes alternative fuel firing in
the calciner verified by the success these types of calcinershave in the HeidelbergCement group burning hard to burn fuels(solid alternative fuels)
Geometry has an important influence on overall calciner
performance verified by testing done by HTC in 2000.
Antoing geometry is best for particle retention time and mixing,but retention time should be more verified by testing done byHTC in 2000 and internal HTC standards
Calciner with good geometry requires a gas retention time ofabout 5 seconds to assure good burnout of solid alternative fuels Verified by Antoing data and supported by design of new
installations
Gas mixing and particle retention time are important parametersthat we as a group could learn a lot from with regards tooptimizing calciner designs for alternative fuel firing
8/10/2019 Calciner Technology in AF Firing
21/22
Conclusions
The effectiveness of a loop duct creating good mixingbehavior is limited, therefore a mixing chamber (deflection)in top of loop duct is important. Investigations andreporting on UB deflection chamber results will be
important, including build-up tendencies.
A great deal could be learned from computer modeling ofcalciner systems. Purpose of modeling is to thoroughlyinvestigate geometry with the target of finding an optimizedcombination of gas mixing, particle retention time and lowbuild-up tendencies.
Small scale modeling (water bead and acid / alkalimodeling), might in particular be useful to investigateexisting calciner designs/problems. FCT-Combustionsupplies this type of service to the cement industry.
8/10/2019 Calciner Technology in AF Firing
22/22
Top Related