Pyro Processing

CEMENT PROCESS ENGINEERINGVADE-MECUM

Rev. 2002

6. PYROPROCESSING

CEMENT PROCESS ENGINEERING SECTION 6 – PYROPROCESSINGVADE-MECUM

Index - iRev. 2002

Table of Contents

1. Kiln Typical Values ..............................................................................6.12. Quick Overview Kiln Exit Gas Calculation .........................................6.1

2.1 Calculation of Various Components ..............................................6.12.2 Typical Fuels Composition............................................................6.22.3 Kiln Exit Gases for Different Fuels ...............................................6.2

3. Pyroprocessing Reactions by Zone.......................................................6.33.1 Evaporation Zone .........................................................................6.33.2 Dehydration Zone.........................................................................6.33.3 Decarbonation Zone......................................................................6.33.4 Clinkering Zone............................................................................6.43.5 Cooling Zone................................................................................6.4

4. Cyclone.................................................................................................6.44.1 Pressure Drop...............................................................................6.44.2 Thermal Efficiency .......................................................................6.54.3 Trapping Efficiency ......................................................................6.54.4 Calculation of Material Flow ........................................................6.5

5. Chains...................................................................................................6.55.1 Guideline......................................................................................6.55.2 Lafarge Corp Data........................................................................6.6

6. Cooler...................................................................................................6.86.1 Compartments ..............................................................................6.86.2 Fans .............................................................................................6.86.3 Cooler Efficiency Coefficients.......................................................6.96.4 Typical Heat Balance Davenport Cooler...................................... 6.11

7. Kiln Heat Balance............................................................................... 6.127.1 Theoretical Heat for Clinker Formation....................................... 6.127.2 Wall Losses................................................................................ 6.127.3 Kiln Residence Time................................................................... 6.137.4 Water Spray ............................................................................... 6.157.5 Heat Balance Example................................................................ 6.15

8. Volatile ............................................................................................... 6.178.1 Properties of Volatile Elements ................................................... 6.178.2 Volatilization Process................................................................. 6.198.3 SO2 - SO3.................................................................................. 6.20

8.4 Build-up and Rings ..................................................................... 6.228.5 Volatile Balance Example : Davenport 1997................................ 6.238.6 Circulation in Preheater (Port-la-Nouvelle).................................. 6.25

9. Lafarge Corp Typical Ratios ............................................................. 6.2610. 57 Clinker Reactivity Study (P. Barriac) ........................................... 6.27


6.1Rev. 2002

1. Kiln Typical ValuesProcess Type Long Dry Long Dry 1-stage 4-stage 4-stage 4-stage

Units Wet <1000 T/D >1000 T/D Preheater Preheater Precal AT Precal ASRatios to Kiln Dimensions

Production per unit volume MTPD/m3 0.6 0.9 0.6 0.6 1.9 2.3 2.9Production per unit brick surface MTPD/m2 0.5 0.7 0.7 0.7 1.8 2.6 3.1Production per unit BZ c/section MTPD/m2 8.1 113 108 104 132 166 172Kiln slope degrees 1.3 1.8 2.2 1.7 2.3 2.3 2.3Chain load T/MTPD 0.1 0.12 0.12 0.06Length/diameter ratio 37 38 37 33 17 15 13Enlarged section vs total length percent 0 0-20 25 25Kiln speed rpm 1 1.4 1.4 1.5 2.5 3 3Shell circumferential speed m/min 12 15 20 22 32 32 40Total material retention time min 231 123 96 102 24 17 15

Fuel and Gas FlowSpecific heat consumption - base kcal/kg 1250 1000 950 900 800 775 750Burning zone gas flow Nm3/kg 1.7 1.2 1.1 1.0 0.9 0.7 0.3Calcining zone gas flow Nm3/kg 2.0 1.4 1.4 1.3 N/A N/A N/AKiln exit gas flow Nm3/kg 2.8 1.8 1.7 1.4 1.2 1.0 0.5Preheater exit gas flow 1.4 1.3 1.2 1.1Conditioning water flow Nm3/kg 0.1 0.1 0.2 0.2 0.2 0.2Stack gas flow @ 7% O2 Nm3/kg 4.0 2.5 2.4 2.3 2.1 1.9 1.8Stack gas density kg/Nm3 1.22 1.30 1.30 1.37 1.39 1.39 1.50Burning zone thermal load Gcal/m2/hr 4.2 4.7 4.3 3.9 4.4 4.3 2.2

Heat Outputs from Kiln/Cooler/PreheaterCooler vent gas %SHC 2.0 12.0 12.0 12.0 15.0 13.0 13.0Solid fuel drying gas %SHC 3.0 2.0 2.0 2.0 2.0 2.0 2.0Kiln/preheater exhaust gas %SHC 14.0 29.0 27.0 25.0 20.0 19.0 18.0Shell radiation %SHC 10.0 11.6 12.2 10.0 6.0 6.0 5.0Preheater vessel radiation %SHC 1.0 2.0 2.0 2.0Heat of formation of clinker %SHC 33.0 41.8 44.0 46.4 52.3 53.9 55.7Drying of raw meal or slurry %SHC 36.0 1.2 1.3 1.3 1.5 1.5 1.6Clinker sensible heat exit cooler %SHC 1.0 1.5 1.6 1.7 1.9 1.9 2.0Unaccounted 1.0 0.9 0.0 0.6 -0.6 0.6 0.7

Total %SHC 100.0 100.0 100.0 100.0 100.0 100.0 100.0

Incremental loss per % dust wasted kcal/kg 20 4 4 4Incremental loss per % bypass kcal/kg 4 3.6 2

2. Quick Overview Kiln Exit Gas Calculation

2.1 Calculation of Various Components

a. CO2 from Calcination (LOI)

• LOI RMdrykg/kg100

M092.1C786.0 +=

kgkk/kgLOI100

100*

100

M092.1C786.0

−+=

• Typical value: 0.533 kg/kgkk0.35 kg/kg RM0.272 Nm3/kgkk

b. H2O from Slurry Moisture

• H2O RMdrykg/kgSM100

SM

−=

kgkk/kgLOI100

100*

SM100

SM

−−• Typical value: 0.865 kg/kgkk

1.08 Nm3/kgkk


6.2Rev. 2002

c. H2O from Water Spray

• WS liters/kgkk = WS kg/kgkk

• Typical value: 0.10 kg/kgkk0.124 Nm3/kgkk

d. Excess Air

•OXY21

OXY*KEGNEA

−=

• Typical value: 0.105*KEGN Nm3/kgkk

2.2 Typical Fuels CompositionCoal Mass% (dry basis) Oil Mass% Gas Volume%

C 65.0 C 86.0 CH4 97.25H 5.0 H 11.0 C2H6 0.98O 5.0 O 0.5 C3H8 0.03S 2.0 S 2.0 N2 1.33

Ash 23.0 N 0.5 CO2 0.4LHV 27214 MJ/t LHV 41320 MJ/t LHV 35.51 MJ/Nm3

2.3 Kiln Exit Gases for Different FuelsCoal Nm3/kgkk % volume

CO2 H2O N2 O2Preca 1.37 31 5 61 2.8Long dry 1.47 30 6 61 1.9Wet 3.06 17 39 42 1.2

Oil Nm3/kgkk % volumeCO2 H2O N2 O2

Preca 1.38 30 7 60 2.8Long dry 1.48 29 8 61 1.8Wet 3.07 16 49 42 1.2

Natural Gas Nm3/kgkk % volumeCO2 H2O N2 O2

Precal 1.45 25 13 59 2.6Long dry 1.57 24 14 59 1.7Wet 3.2 13 44 41 1.1

Oxygen vs. Excess Air Excess at (% of neutral comb gas)%O2 in KEG Process Coal Oil Gas1.0 Precal

Long dryWet

6.46.15.7

6.36.05.6

6.05.85.4

2.0 PrecalLong dryWet

13.412.912.1

13.212.711.9

12.612.111.3


21.220.419.1

20.820.118.8

19.919.217.9


29.928.826.9

29.428.426.5

28.127.125.2


6.3Rev. 2002

3. Pyroprocessing Reactions by Zone1

��

100

80

60

40

20 Quartz

masses

%

Cristob.

200 400 600 800 1000 1200 1400

Fe2O3 C2(A,F) C12A7 C4AF C3A

100

80

60

40

20

clays

Clays

Ca CO3 CaO

CO2H2O

T °C

C2S

3C3S

0

Quartzα βLiqu.

3.1 Evaporation Zone• Between 100 and 400ºC: H2O (l) + heat → H2O (g), ∆H = 44.2 kJ/mol

3.2 Dehydration ZoneBetween 350ºC and 650ºC• Clay starts to lose its water of crystallization:

OH2OAl.SiO2HeatOH2.OAl.SiO2 23222322 +→ , ∆H = + 202 kJ/mol

At 400ºC• Magnesium carbonate’s decomposition pressure reaches atmospheric pressure at this temperature:

23 COMgOHeatMgCO +→+ , ∆H = + 117 kJ/mol

• Vaporization and oxidation of organic compounds and sulfides:

33222 SO4OFeO2

7FeS2 +→+

At 550ºC• CaCO3 starts to decompose at this temperature. However, acidic environment favours the deformation of the

molecules of CaCO3.

3.3 Decarbonation ZoneAt 900ºC• This is the zone where CaCO3 decomposes rapidly into CaO and CO2 because of its decomposition pressure

at this temperature:

23 COCaOCaCO +→ , ∆H = + 178.2kJ/mol

• Much free lime is produced and starts to react:

22 SiO.CaO2SiOCaO2 →+ , ∆H = -125.9kJ/mol

3232 OAl.CaO2OAlCaO2 →+ ,

1 Each enthalpy of reaction is given @25°C, according to G.Seidel, H.Huckauf and J.Stark: “Technologie des Bindebaustoffe Brennprozess und Brennanlagen”


6.4Rev. 2002

3232 OFe.CaO2OFeCaO2 →+ , ∆H = -31 kJ/mol

• Free CaO combines with SO3 to give anhydrite:

43 CaSOSOCaO →+• This anhydrite reacts with the alkalies from clay to give alkali sulphates:

4224 SONaCaOONaCaSO +→+SONa.SOK3orSOKCaOOKCaSO 2424224 +→+

• The quantity of SO3 is generally insufficient to combine with the alkalies:

3832 ANaCACONa →+ 122322 SKCSCOK →+

3.4 Clinkering ZoneAt 1200ºC• Belite ( SC2 ) formation completed: 22 .22 SiOCaOSiOCaO →+ , ∆H = -125.9 kJ/mol.

712AC becomes enriched in lime and changes toAC3

AC2 and FC2 form a solid solution : AFC4 , ∆H = -50.4 kJ/mol

Between 1250ºC and 1450ºC• AC3 and AFC4 liquefy and constitute the flux. SC2 combines with freeCaO to form SC3 in the presence

of flux, forming nodules: SCSCCaO 32 →+ , ∆H = +8 kJ/mol.

• The alkali sulfates decompose, liberating alkalies and2SO :

↑+↑+→+ 22242 O2/1SOORHeatSOR

• Anhydrite decomposes intoCaO and 2SO :

↑+↑+→+ 224 O2/1SOCaOHeatCaSO , ∆H = +490 kJ/mol.

• Ferric oxide, in a reducing atmosphere, changes to ferrous oxide:↑+→ 22 O2/1FeO23OFe

3.5 Cooling ZoneAt 1400ºC to 1250ºC,

• The 1α form SC2 crystallizes to the more hydrolizable SC2β form.

• The AC3 and AFC4 crystallize and finally the molten sulfates crystallize.

4. Cyclone

4.1 Pressure Drop• TheDp through a cyclone for a family of

similar cyclones:

4

2

D

QrcstDp ∗∗=

where:- Dp is the pressure drop through the cyclone- r is the fluid density- Q is the gas flow- D is the diameter of the cyclone


6.5Rev. 2002

4.2 Thermal Efficiency

•go

mogoth T

TT1h

−= −

where:- goT is the temperature of gas at cyclone outlet

- goT is the temperature of material at cyclone discharge

• A normal value for thermal cyclone efficiency is above 95%. This definition is commonly used but the name"Thermal efficiency" can be considered misleading because the useful heat gained by the material at thecyclone discharge is also related to the cyclone trapping efficiency.

4.3 Trapping Efficiency

•i

oit D

DDh

−=

where:- Di is the dust load of gas at cyclone inlet

- Do is the dust load of gas at cyclone outlet

• The current value for the trapping efficiency of the top cyclone is around 95%. It was commonly accepted inthe past that the bottom cyclones had a lower efficiency (75-85%) but series of measurements and towersimulation showed a higher efficiency for these cyclones (around 90%).

4.4 Calculation of Material Flow• With the two following equations expressing

the total flow conservation and the tracerflow (i.e. K2O), the recirculation level can be

assessed.- CAKLKDkk FFFF +=+- CACAkkKLKDkkkk KFKFFKF ∗+∗=+∗

where:- KDF : The kiln dust flow (LOI=0)

- KLF : The kiln load flow (LOI=0)

- kkF : The clinker flow (LOI=0)

- CAF : The coal ash flow (LOI=0)

- kkK : Tracer concentration in clinker

- KDK : Tracer concentration in kiln dust

- KLK : Tracer concentration in kiln inlet

- CAK : Tracer concentration in coal ash(if ash has to be added)

5. Chains

5.1 GuidelineZone Target (wet) Dry kilnFree zone length (ratio to kiln diameter) 1.0 to 1.5 1.0 to 1.5Dust M2/m3 11.0 to 15.0 11.0 to 15.0

Chain length (% of kiln diameter) <75% <75%Plastic zone length (ratio to kiln diameter) 1.0 to 4.0 N/A

M2/m3 5.0 to 8.0 N/AChain length (% of kiln diameter) 60% to 70% N/A

Preheat lower section zone length (ratio to kiln diameter) 0.5 to 2.5 0.5 to 2.5M2/m3 7.0 to 10.0 7.0 to 10.0Chain length (% of kiln diameter) 70% 70%

Preheat upper section zone length (ratio to kiln diameter) 0.5 to 2.5 0.5 to 2.5M2/m3 6.0 to 8.5 6.0 to 8.5Chain length (% of kiln diameter) 70% 70%


6.6Rev. 2002

Zone Target (wet) Dry kilnRadiation zone length (ratio to kiln diameter) 1 1

M2/m3 8.5 to 11.0 8.5 to 11.0Chain length (% of kiln diameter) 70% 70%

Global m2/mtpd 2.5-2.8 2.3 – 2.6Global kg/mtpd 110-130 105-110Global length Ratio to kiln diameter 6-10 5 – 8Global length % kiln length 18-25% 17 – 22%

(sources: Marc Brunelle)

• Chain surface: 19m2/t for oval chains vs. 22-25 m2/t for round chains.• For small kilns, ratios are always lower than for larger kilns.• Ratios are higher for dry kiln compared to wet kiln.• Chainless sectionsare applied along chain zone aiming to:

- equalize gas temperatures- serve as a buffer area to equalize varying rates of material transportation- precipitate kiln dust- allow for installation of thermocouples

Other Rules of Thumb• 1500 m of installed chains reduces the exit chain gas temperature by 100oC.• A properly designed chain system can lower the SHC by 300 kcal/kg ck.• heat exchange rate: 8.75 kcal/h/m2/C.• pressure per one meter of chain: 1-2 mm H2O for curtain chain and 2-3 for Gartand chain (note: Garland

chains are abandoned due to practical considerations in maintaining hanging pattern).• For Gartand chain, the thermal effect is 1.5 time higher than curtain chain.• Wear rate: 80-120 g/t ck for wet kiln and 100-150 for dry kiln.

5.2 Lafarge Corp DataKiln Type Impact Chain densitiesupdated Feb 99 plates Specific Area Gross Area Area Ratio Specific Weight Gross Weight Weight Ratio

M.Brunelle (CTS) m2/m3 m2/m3 m2/mtpd kg/m3 kg/m3 kg/mtpd

C1-C2 C2 C1-C2 C2

(less FE void) (plus all voids) Nominal Prod. (less FE void) (pluss all voids) (Nominal Prod.)

BTH K1(1999) 1SPH 6.46 4.39 1.36 260.12 176.77 54.79BTH K1(1998) 1SPH 6.44 4.38 1.17 260.26 176.77 47.14JPA K2 (1998) 1SPH 6.33 4.93 2.57 242.82 189.32 98.46

Averages 6.39 4.65 1.87 251.54 183.05 72.80

STC K1 Dry(cros)

4.90 4.18 1.76 303.00 258.57 109.18

BFD K2 (1998) Dry 5.70 4.70 1.50 269.30 221.90 71.00ESW K4 (1999) Dry 7.46 5.44 2.96 303.21 220.92 120.37ESW K4 (1998) Dry 7.42 5.36 3.08 301.27 217.89 125.02STC K2 (1998) Dry 6.96 6.48 2.44 317.93 296.23 111.57SCK K1(1998) Dry 8.21 6.34 2.10 309.56 238.92 79.14SCK K2 (1998) Dry yes X1 7.79 6.16 2.21 274.44 216.96 77.90

Averages 7.26 5.75 2.38 295.95 235.47 97.50


6.7Rev. 2002

Kiln Type Impact Chain densitiesupdated Feb 99 plates Specific Area Gross Area Area Ratio Specific Weight Gross Weight Weight Ratio

M.Brunelle (CTS) m2/m3 m2/m3 m2/mtpd kg/m3 kg/m3 kg/mtpd

C1-C2 C2 C1-C2 C2

(less FE void) (plus all voids) Nominal Prod. (less FE void) (pluss all voids) (Nominal Prod.)

FDA K1(1998) Wet yes X2 4.95 4.36 2.72 280.57 246.86 154.36FDA K2 (1998) Wet yes X1 5.90 5.13 3.00 333.31 289.84 169.66RMD K1(1998) Wet 7.16 6.23 2.68 283.75 247.01 106.16RMD K2 (1998) Wet yes X1 6.54 5.28 2.62 291.05 234.90 116.66SEA (1998) Wet 4.82 4.07 2.72 189.23 159.84 106.76

Averages 5.88 5.01 2.75 275.58 235.69 130.72


6.8Rev. 2002

6. Cooler

6.1 CompartmentsCompartments number

<800 tpd: 4 compartments800-1200 tpd: 5 compartments1200-2000 tpd: 6 compartments

2000-3000 tpd: 7 compartments3000-4000 tpd: 8 compartments>4000 tpd: 9 compartments

• To the middle of the cooling zone, the ratio between compartment area will be 1.4 (except for the #2).

Recuperation zone

•CNkH1440

QI

∗∗∗∗∗=

ρ.

where:- l: cooler width- Q: clinker flow (t/day)- ρ : Clinker apparent density (t/m3) generally 1.25- H: bed depth (m)- k: grate efficiency (0.70 for flat grates)- N: number of stroke per minute (usually 10 to 14spm)- c: the grate course (m)

• N has to be chosen to allow 1.6 * N in case of push.• The length of the recuperation zone will be set with an air density between 1.45 Nm3/m2*s (Fuller) and 1.55

(IKN) and a heat consumption 800 kcal/kg and 0.85 Nm3/kgkk for the combustion air.

Cooling zone• The cooler loading will be the factor determining the cooling zone length:

- 40 t/m2/day dry process (high pressure fans thick bed depth (60 cm))- 35t/m2/day wet process (high pressure fans)- 28 t/m2/day all processes (low pressure fans, thin bed depth (30 cm))

Rules of thumb• Air velocity above clinker bed: 5 to 7m/s.• 6 to 10 strokes per minute, cooler stroke length around 5”, clinker speed around 1 to 1.2 m/min.• Clinker granulometry: passing 0.5mm:<15% , remaining at 25mm<10%.• Void volume: about 0.4 to 0.5.• Clinker bulk density: 89 to 120 lb/ft3.• Grate cooler: 5-10 kWh/ t, target should be below 5 kWh/t w/o vent air fan.

6.2 FansRecuperation zone• Maintain the flow during a kiln push: the fan maximum pressure has to be 30% higher than the nominal. At

constant flow, 15% of security to absorb the pressure variation. It is also a good security to keep 30% of flowreserve between the peak of the curve and the nominal.

• In the kiln, minimum cooling rate between 1450 and 1300C: 20C/min.


6.9Rev. 2002

Cooling zone• They should be able to go from 2.5 to 3 Nm3/kg during a push. Their curve should be flatter and their

maximum pressure 30% above the functioning point. 20% increase in flow has to keep 15% safety margin onpressure. Minimum is 30 mbar for single-stage cooler.

Rules of thumb• Grate plate resistance is directly related to the air flow and represents about 15% of total air resistance.• Basic operating principles:

- Maintain a constant air to clinker ratio- Maintain a constant bed depth- Remove all excess cooling (vent) air

• The longer the air/clinker contact time, the cooler the clinker.• The higher the velocity air, the colder the clinker surface, the higher the heat transfer rate from center to edge

of the clinker but the lower the between air and clinker edge.• Average cooling air flow (Lafarge Corp): 3.7 kg/kg kk, 2.9Nm3/kg kk.• Average grate loading: 30 mt/m2/d (the older the lower usually).

• Secondary air temperature:n.SHC

)K347.(3250T

−= .

where:K: heat loss of the cooler in kcal/kgck,SHCin kcal/kgck,n: excess air (ex:1.1)• Airflow:

Chamber # 1 2 3 >=4Nm3/(m2.s) 2.0-3.5 1.2-1.8 1 <1

6.3 Cooler Efficiency Coefficients

a. Recovery Efficiency (ρ):

•

ca

tasacain,ck

tasa

m

mmhh

hh

inputheatusabletotal

gasesrecoveredbygainedheat+

+

+==ρ

where :- msa=mass of secundary air in kg/h andhsa is the enthalpy of secondary air in kcal/h- mta=mass of tertiary air in kg/h andhta is the enthalpy of tertiary air in kcal/h- mca=mass of cooling air in kg/h andhca is the enthalpy of cooling air in kcal/h

• This efficiency depends highly on the quantity of air recovered by combustion. It is higher for wet kilns(∼90%) than for dry kilns (∼70%).

b. Cooling Efficiency

•inck,

outck,inck,

h

h-h

clinkerininputheat

clinkerbylostheat==η

c. Recovery Factor (k)

• ( )tam

tasa mmk +=

+−= samk-e-1or

)1(ln ρρ

- k = 0.9⇒ bad cooler- k = 1.1⇒ poor cooler

- k = 1.3⇒ good cooler- k = 1.6⇒ excellent cooler


6.10Rev. 2002

d. Cooler Loss• Cooler loss = all heat not recovered by combustion air.• Cooler loss = heat content of clinker leaving cooler )h( out,ck :

+ heat content of vent air + heat content of coal mill air+ heat content of raw mill air + wall heat losses

e. Typical Values(Lafarge Corp data) min max Av. min max Av.

k 0.83 1.67 1.25 η 92% 97.2% 95%Cooler loss (kcal/kgkk) 60 180 120 ρ 51% 85.7% 70%


6.11Rev. 2002

6.4 Typical Heat Balance Davenport CoolerCooler heat & mass balance Davenport cooler Final balance

Date:Sept 16 to 18, 97Clinker (T/d): 2537Clinker (kg/h): 105725 Ref. temperature: 0°C

IN volume volume mass mass Temp. Heat HeatNm³/h Nm³/kg ck kg/kg ck kg/h ºC kcal/h kcal/kg ck

Cooling air 225671 2.13 2.76 291643 37 2613673 24.7Hot clinker 1.00 105725 1350 36638913 346.5Total 225671 2.13 3.76 397368 39252586 371.3

OUTSecondary air 23016 0.22 0.28 29745 974 7540626 71.3Tertiary air 71770 0.68 0.88 92751 874 20901034 197.7Raw mill take-offCoal mill take-off 16232 0.15 0.20 20978 317 1623430 15.4Vent air 114652 1.08 1.40 148170 167 5976961 56.5Cold clinker 1.00 105725 143 2916855 27.6Wall loss 293680 2.8Total 225671 2.13 3.76 397368 39252586 371.3

Difference: 0 0.00 0.00 0 0 0.0

0.00% 0.00% 0.00% 0.00% 0.00% 0.00%

ρ: 75.37%(recovery ratio) k: 1.56η: 92.04%(cooling efficiency) Cooler loss: 102.26kcal/kgck

Tertiary air Vent

0.68 Nm³/kg ck 1.08 Nm³/kg ck

0.22 Nm³/kg ck 874°C Coal mill 167°C

974°C 0.15 Nm³/kg ck

Secondary air 317°C

Clinker

105725 kg/h

1350°C

Cooling air Clinker

2.13 Nm³/kg ck 105725 kg/h

37°C 143°C


6.12Rev. 2002

7. Kiln Heat Balance

7.1 Theoretical Heat for Clinker FormationPerray• From clinker analysis: ( ) 32232 OFe60.0SiO11.5CaO64.7MgO47.6OAl11.4ckkg/kcalQ −−++=

Lafarge Model

• Exothermic reaction100

160

228

172SCSCQE 32 ∗

+=

• Decarbonization 242 T1022.0T1066.05.437QD ∗−∗+= −−

where:- QE in kcal/kgkk

- QD in kcal/kg 3CaCO- T is the decarbonatation temp (ºK)

• Qtheo= QD - QE

7.2 Wall Losses

a. General Formula• )1T2T(SWL −= α

where:- WL is the losses in kcal/h- S is the area in m2- T2 is the wall temperature (ºC)- T1 is the ambient temperature (ºC)- α is defined in the following graph

0

5

10

15

20

25

30

35

40

45

50

55

60

65

100 200 300 400 500 600

T - T° (C)

W/M2C

v = 14 m/s wind

1312

11

10

9

87

6

5

43

2

1

v = 0 m/s (free convection)

SS = 0.9

Ambient T° - 20°C

Wind:0m/s

α


6.13Rev. 2002

b. Radiation

• hm/kcal100

273te

100

273tp*96.4*Loss 2

44

+−

+=∈ with: tp: wall temperature,te: external temp. (in C)

Emissivity:∈material ∈bricks 0.8steel 0.95For oxidized steel ∈=0.996-2.88*10-4.(tp-100)For dusty kiln shell ∈=0.96-5.2*10-4.(tp-100)For silica bricks ∈=0.81-6.08*10-4.(tp-200)

Other data tp ∈ tp ∈Iron oxide 500C 0.78 Steel oxide 40C 0.94Zinc galvanized sheet bright 28C 0.23 Steel oxide 370C 0.97Iron polished 425C 0.144 Steel polished 770C 0.52Steel dense shinny oxide layer 25C 0.82 Steel pipe 200 0.8

Emissivity Error measurement: ExampleRead temperature=65C, emissivity choosen: 1 instead of actual: 0.4

True temperature= C152K4254.0/1).65273(t 4 ==+=Loss calculated with read temperature=290kcal/h/m2, Loss with true temperature=510 kcal/h/m2

c. Convection

• hm/kcal)tetp(*Loss 225.1−= αα : coef exchange

2.6 for vaults2.2 vertical surfaces

7.3 Kiln Residence TimeRules of thumb:• Long kiln: 2-4 hours (Lafarge Corp. average: 155 min), short kiln:40 to 60 minutes.• RPM from 1.5 to 2.5 (short kiln), Long Kiln: 1.2 to 1.8, Lafarge Corp. average: 1.34.• Le Teil (1998): 1.5 to 2.3RPM improved clinker granulometry: Retained at 20mm: 7.2 to 13.5%, R10mm:

25to 37%

Perray

•SdN

L19.0T

∗∗∗=

with:- L Kiln length (m)- N Kiln speed (rpm)- d kiln diameter (m)- SKiln slope (m/m)

Material speed• Lafarge model in calcination zone:

TsTf

TfTsTmSdN

Vm−

+−∗∗∗= 2

19.0

with:- Vm: the speed at m- Tm: mat temp at m- Ts: temp where calcination begins- Tf: temp where calcination ends


6.14Rev. 2002


6.15Rev. 2002

7.4 Water Spray

• Flow needed =ft

TTswhkg

.9.538)100(

).(./

2

21

+−−= where: T1 andT2: uncooled and cooled temp (C) of the gas,w:

gas rate (kg/h),s: specific heat of gas (kcal/kg),t2:water temp. (in C),f :% water evaporated (decimal).• Lafarge corp : from 0 to 0.26kg water/kg clinker, average: 0.14.

7.5 Heat Balance Example

a. Davenport 1997 Flow Sheet


6.16Rev. 2002

b. Precalciner Heat Balanceplant Davenport kiln Kiln 1 date 13/11/97

Precalciner specific heat consumptio n584 kcal/kg ck

heat in %mass kg/hrTemp(°C) kcal/kg kcal/hr kcal/kg ck heat out %mass kg/hr

Temp(°C) kcal/kg kcal/hr kcal/kg ck

Air 99617 712 181.98 18127832 172.52 Tower Exit Gas 188391 358 100.84 18997182 180.80Primary air 1 2.00% 1992 10 2.40 4788 0.05 O2 2.13% 4013 81.97 328920 3.13Primary air 2 2.00% 1992 10 2.40 4788 0.05 CO2 45.82% 86313 83.08 7170647 68.24Inleakage 1 10.00% 9962 10 2.40 23938 0.23 H2O 2.18% 4103 759.59 3116709 29.66Inleakage 2 0.00% 0 10 2.40 0 0.00 SO2 0.18% 338 59.90 20229 0.19Tertiary air 86.00% 85670 823 211.21 18094318 172.20 N2 48.87% 92067 90.06 8291338 78.91Preheater feed 190500 61 11.84 2256252 21.47 Ar 0.83% 1558 44.51 69337 0.66H2O 0.00% 0 61.04 0 0.00 Bypass Gas 21000 440 126.82 2663285 25.35Kiln Dust 0 300 68.65 0 0.00 O2 2.00% 420 102.07 42869 0.41Return Dust 0 350 81.80 0 0.00 CO2 32.14% 6749 104.95 708259 6.74Coal/Coke 8334 60 16.57 138056 1.31 H2O 2.84% 596 800.12 476879 4.54Combustion 7361.60 61349445 583.86 SO2 3.77% 791 75.39 59662 0.57H2O 1.34% 112 60.04 6705 0.06 N2 58.27% 12237 111.49 1364285 12.98Natural Gas 0 80 43.21 0 0.00 Ar 0.99% 207 54.74 11332 0.11Combustion 0 0 0.00 Bypass Dust 3810 400 85.46 325607 3.10H2O 0.00% 0 80.15 0 0.00 Kiln Feed 112921 850 197.04 22249876 211.75WDF 0 80 44.98 0.00 0.00 Heat of Formation 412.02 46526066 442.79Combustion 0.00 0.00 0.00 Tower Exit dust 22000 340 79.13 1740957 16.57H2O 0.00% 0 80.15 0 0.00 Wall Losses 22.00 2484260 23.64Kiln Gases 49672 904 258.36 12833217 122.13

total in 348122 94711507 901.37 total out 348122 94987233 904.00

difference 0 275726 2.620.00% 0.29% 0.29%

c. Kiln Heat Balanceplan t Davenport kiln Kiln 1 Date 13/11/97

kg/hr kg/kg ckfuel kg/hr Temp (°C) LHV (kcal/kg) Tot. kcal/kg Clinker 105075 1.00Coke/Coal 3572 60 7362 26354660 Kiln Feed 112921 1.07Natural Gas 0 15 0 0.00 Return Dust 0 0.00Waste Derived Fuel 0 0 0 0.00 Waste Dust 0 0.00

total combustion air %vol Nm3/hr %mass kg/hr Temp (°C) neutral combustion air %mass kg/hrTotal Combustion Air 29600 38254 Neutral Combustion Air 35852

O2 23.15% 8300Primary Air 1 4.78% 1415 4.78% 1828 27 CO2 0.04% 14Primary Air 2 6.21% 1837 6.21% 2374 25 H2O 0.00% 0Inleakage 1 10.00% 2960 10.00% 3825 25 SO2 0.00% 0Inleakage 2 0.00% 0 0.00% 0 25 N2 75.53% 27079Secondary Air 79.01% 23388 79.01% 30226 1065 Ar 1.28% 459

total kiln gas %vol Nm3/hr %mass kg/hr Temp (°C) neutral combustion gas %mass kg/hrTotal Kiln Gas 34667 49672 904 Neutral Combustion Gas 39195O2 2.01% 696 2.00% 993 O2 0.00% 0CO2 23.45% 8130 32.14% 15963 CO2 25.71% 10076H2O 5.06% 1754 2.84% 1410 H2O 3.60% 1410SO2 1.89% 655 3.77% 1872 SO2 0.31% 121N2 66.80% 23158 58.27% 28944 N2 69.22% 27130Ar 0.79% 275 0.99% 490 Ar 1.17% 459

excess air kg/hr water spray kg/hr Temp (°C)Excess Air 2402 H2O spray 0 10


6.17Rev. 2002

d. Kiln Summaryplant Davenport kiln Kiln 1 date 13/11/97

Kiln specific heat consumptio n250 kcal/kg ck

heat in %mass kg/hrTemp(°C) kcal/kg kcal/hr kcal/kg ck heat out %mass kg/hr

Temp(°C) kcal/kg kcal/hr kcal/kg ck

Air 38254 846 221.92 8489285 80.79 Total Gas 49672 904 258.36 12833217 122.13Primary air 1 4.78% 1828 27 6.50 11884 0.11 O2 2.00% 993 221.81 220355 2.10Primary air 2 6.21% 2374 25 6.01 14256 0.14 CO2 32.14% 15963 239.69 3826133 36.41Inleakage 1 10.00% 3825 25 6.01 22974 0.22 H2O 2.84% 1410 1049.74 1479875 14.08Inleakage 2 0.00% 0 25 6.01 0 0.00 SO2 3.77% 1872 168.70 315788 3.01Secondary Air 79.01% 30226 1065 279.23 8440171 80.33 N2 58.27% 28944 239.63 6935970 66.01Kiln Feed 112921 850 609.06 68775942 654.54 Ar 0.99% 490 112.52 55097 0.52H2O 0.00% 0 0.00 0 0.00 Clinker 105075 1358 349.49 36723000 349.49H2O Spray 0 10 9.97 0 0.00 Heat of Formation 420.00 44131394 420.00Return Dust 0 300 68.65 0 0.00 Exit dust 0 400 95.32 0 0.00Coal/Coke 3572 60 16.57 59167 0.56 Wall Losses 75.00 7880606 75.00Combustion 7362 26292619 250.23H2O 1.34% 48 60.04 2873 0.03Natural Gas 0 15 7.70 0 0.00Combustion 0 0 0.00H2O 0.00% 0 14.97 0 0.00WDF 0 0 0.00 0.00 0.00Combustion 0 0.00 0.00H2O 0.00% 0 0.00 0 0.00

total in 154747 103619887 986.15 total out 154747 101568217 966.63

difference 0.00 -2051671 -19.530.00% -2.02% -2.02%

8. Volatile

8.1 Properties of Volatile Elements

a. Basic Volatile Properties• The raw mix comes with some minor elements (potassium, sodium, sulphur and chlorides) called volatiles.

Element Compound Formula MolecularWeight

MeltingPoint °C

BoilingPoint °C

Heat of Formation- ∆H°f kJ/mol

Na

OxideHydroxideCarbonate

SulfateChloride

Na2O

NaOHNa2CO3Na2SO4

NaCl

62.040.0

106.0142.058.4

820322851884801

d1390

d—

1465

416427

11311385411

K


SulfateChloride

K2O

KOHK2CO3K2SO4

KCl

94.256.1

138.2147.374.6

887410891

1069776

d1327

d16891410

362426

114614341436

Ca


SulfateChlorideFluoride

CaOCa (OH)2CaCO3CaSO4CaC12CaF2

56.174.1

100.1136.1111.078.1

2580dd

d≈ 1280 (1450)772

1380

2850———

1600—

636987288

1430795—

d=Decomposes, s=Sublimates


6.18Rev. 2002

b. Eutectic• In a multicomponent-system the melt formation is governed by eutectics. Eutectic is a mixture of two or more

substances that have a melting point lower than any of the substances of the mixture.

Eutectic Melting

System Concentration(% mole)

Melting point(°C)

Na2SO4 — CaSO4 52 — 48 900K2SO4 — CaSO4 58 — 42 867K2SO4 — Na2SO4 23 — 77 823K2CO3 — CaCO3 60 — 40 750K2CO3 — Na2CO3 42 — 58 710K2SO4 — KCl 40 — 60 690KCl — CaSO4 68 — 32 688KCl — NaCl 50 — 50 640NaCl — Na2SO4 65 — 35 630KCl — CaCl2 25 — 75 600NaCl — CaCl2 50 — 50 500

c. Vapor Pressure

Vapor Pressure for Volatile Compounds at Different Temperaturesmm Hg

100

200

300

400

500

600

700

760

700 800 900 1000 1100 1200 1300 1400 1500 °C

NaOH

KOH

KCl

NaCl

Na CO2 3

K CO2 3K SO

42

Na SO2 4

Caution:This graphic is for trend indication only.We have no indication of the precision of thecurves. Do not use for calculation.Thus, for instance, K is more volatile than Na.

d. Typical Chemical Reaction

• ( ) 22m4n O2

mSOmMeOnSOMe ++↔ where: Men can be: Ca, K2,Na2

• The equilibrium constant of that reaction has this formula:[ ] [ ] [ ]

( )mn

mmn

SOMe

OSOMeOK

4

2/22=


6.19Rev. 2002

e. Parameters Influencing the Volatilisation Process

Influence of kiln gases on the volatility of the circulating elements

Kiln atmospherevapor pressure

Sodiumv

Potassiumv

Sulphurv

Chloridev

CO2 ⇑ ⇓ ⇓ ⇑

H2O ⇑ ⇑ ⇑ ⇑ ⇑

O2 ⇓ ⇑ ⇑⇑

SO2 ⇑ ⇓

Effect of fineness on v at 1300°C

K2O

v

Na2O

v

SO3v

1.7% > 200 µm21.8 % > 90 µm

0.89 0.42 0.63

< 90 µm 0.89 0.46 0.63< 60 µm 0.93 0.45 0.65

8.2 Volatilization Process• Volatiles will start to volatilize (evaporate) from the liquid phase as soon as the temperature increases.• A fraction of those elements (or compounds) will be vaporized in the burning zone and get entrained with the

gases toward the back of the kiln. The vapors will cool down together with the gas stream and recondensebefore leaving the kiln or in the dust collector. The condensation takes place on any cool surface, mostly onthe dust carried by the gas.- Fi : flux of volatile componenti brought by fuel (g/kg ck)- Mi : flux of volatile componenti brought by raw mix (g/kg ck)- Ci : flux of volatile componenti going out with the clinker (g/kg ck)- Li : flux of volatile componenti lost with gas and dust (g/kg ck) ( loss)- Ki : flux of volatile componenti in the kiln load (g/kg ck)- Gi : flux of volatile componenti in the gas stream (g/kg ck)

a. Volatile Recirculation Model

FuelExit gas& dust

ClinkerRaw mix

Gas & dust

Kiln load

Trapping Volatilization

• Kiln load:vt1

MtFK

−+=

• Clinker: ( )MtFvt1

v1C +

−−=

• Gas stream:vt1

FvMG

−+=

• Losses: ( )FvMvt1

t1L +

−−=


6.20Rev. 2002

Typical volatilization and trapping coefficientsType of kiln SO3 K2O Na2O Cl-

v t v t v t v tWet kiln without dust wasting 0.59 0.76 0.45 0.81 0.12 - 0.99 -Wet kiln with dust wasting 0.72 0.63 0.53 0.51 0.24 0.68 0.99 -Long dry kiln 0.65 0.87 0.65 0.81 0.21 0.45 0.99 -Preheater kiln 0.80 0.90 0.69 0.96 0.26 0.79 0.99 0.99Precalciner kiln 0.55 0.96 0.49 0.98 0.55 0.60 0.99 0.99

(Prepared from average volatile balances made within Lafarge)

Typical concentration factors of volatiles in the kiln load(kiln load / raw mix ratio)

Na2O and K2O 2 to 10SO3 4 to 20

Cl- 20 to 100

b. Evolution of Volatiles During Transitions• If M( θ) is a step atθ = 1 then:

( )( ) T/101 vtKKK)(K θθ −+=

where:- K0 : previous kiln load composition- K1 : new kiln load composition

- θ : time (to avoid confusion with t, the trapping coefficient)- T : the time required by a given mass of volatile to complete a cycle- M(θ) : flux of volatile from the raw mix at timeθ- F(θ) : flux of volatile from the fuel at timeθ- K(θ) : flux of volatile in the kiln load at timeθ

Rules of thumb• Circulating kiln load : 1.7 to 2.1 kgload/kg clinker.• Generated dust: Lafarge Corp average for LD kilns:0.6, from 0.2 to 1.34 (BFD).• Generated dust: short kiln: 100 to 150g/kgck, Lepol Grate: 50g/kgck.

c. Volatile Cycle

•v1

tC

−=

- t is the time between the trapping and theburning zone

- v is the volatilization coefficient- C is the cycling time

Chlorine: v = .99 5-6 days:SO3 v = .6 5-7 hours

8.3 SO2 - SO3

a. General• Sulfur is found in:

- Clinker raw material (combined form of sulfur or sulfate).- Combustibles (S in the form of organic components).


6.21Rev. 2002

Sulfur BehaviourSulfur Input Locations to Precalciner

Feed: as SO4, 90-95% captureas FeS2, 35-60% capture

Fuel

Fuel: as SO4 or S,90-95% capt

RM

30-40%capture

Formation in the Burning zone• The following is the thermodynamic

equilibrium of sulfur species in a 10% excessair flue gas. The principal product formed inthe burning zone will be 2SO .

400 600 800 1000 1200 1400

��

��

��

��

��

��

��

��

Temperature (ºK)

%of

tota

lsul

phur

H2SO4 SO2SO3

0

20

40

60

80

100

b. What Affects the SO2 Generation in the Burning Zone?

The composition of the kiln load• Sulfur is preferably linked with alkalies which have a higher stability and a greater chance of being found as

alkali sulfate in the clinker ( 4242 SONa,SOK ) themselves being part of bigger compounds. So if the kiln load

composition has a molar excess of ONaOK 22 − available (not combined with chlorine) vs 3SO , the 2SOgenerated from the load will be lower (sulfur, alkali, molar ratio < 1.2).

The burning zone temperature• At lower temperature, less 4CaSO or alkali sulfates will decompose to form 2SO and the 3SO level in the

clinker will be higher.

The O2 level

0.0 0.5 1.0 1.5 2.0 2.5 3.0Oxygen %

0

500

1000

1500

2000

SO2ppm

SO3

0

0.2

0.4

0.6

0.8

1.0

0 1.0 2.5 5.0 %O2

1400°C

1200°C1000°C

v

The residence time in the burning zone• The longer the time the material stays in the burning zone, the higher the chance for2SO to volatilize.

Back-end• If the raw mix contains sulfur compounds (i.e. 2FeS = pyrite), the combustion of these compounds generates

2SO .


6.22Rev. 2002

c. SO3 Volatilization in Calciner

90 91 92 93 94 95 96 97 98 99 100

��

��

��

��

��

��

��

��

��40

50

60

70

80

90

��

��

��

Combustion efficiency (%)

SO

3vo

latil

izat

ion

(%)

d. Trapping• 2SO is stable above 900ºC but starts to be

trapped by 3CaCO and CaO at lower

temperatures. There is a large excess of

3CaCO in the preheater, which explains a

high trapping coefficient (95% "dry"scrubbing).

Lab experience (H. Ritzmann, Neubeckum).

400 500 600 700 800 900 1000

��

��

��

��

��

0

20

40

60

80

��

��

��

Temperature (ºC)

SO

2tr

appe

d(%

ofto

tal)

• 24223 COCaSOO2/1SOCaCO +→++ .

• In a precalciner kiln, the decarbonated limestone captures more actively2SO , especially with a high level of

Oxygen and the following equilibrium is shifted to the left: 224 O2/1SOCaOCaSO ++↔ .

• For this reason, precalciner kilns are able to absorb rather high concentrations of2SO in the gas coming fromthe kiln.

8.4 Build-up and Rings• After condensation and before solidification of the volatiles, the dust particles will be sticky and tend to

agglomerate on solid objects: kiln walls, chains or lower cyclones of preheater tower.• The sulphur build-up usually occurs where the temperature is between 800°C and 1100°C: kiln walls and

chains for a long kiln, smoke chamber and lower cyclone for a preheater kiln. In those build-ups, the followingsulfates are most commonly found: Arcanite(K2SO4), Anhydrite (CaSO4), Glaserite(K3Na (SO4)2), Ca-

Langbeinite(K2Ca2 (SO4)3) and sulfate spurrite(Ca2 (SiO4)3 CaSO4).

• In a long kiln, the build-ups are formed below the internal exchanger. This takes place in the kiln load so thebuild-ups formed this way are naturally destroyed in the majority of the cases. In small diameter kiln,however, a sulfate ring can appear.

• Chlorine will condense in the600°C to 700°C zones, that is in the chains for a long kiln.• Operational difficulties when the concentration of circulating elements in the load material exceeds the

following levels (on clinker basis):- Na2O + K2O = 3–5 %, SO3 =3–5 %, Cl- =1.2–1.6 %


6.23Rev. 2002

8.5 Volatile Balance Example : Davenport 1997

Flow Loss of ign Moisture SO3 K2O Na2O Clt/h % * % % % % %

Raw mix 168.500 35.410 0.000 0.897 0.500 0.090 0.001Clinker 105.075 0.000 0.000 0.610 0.710 0.130 0.010Kiln load - 5.210 0.000 2.450 1.099 0.760 0.101Recirculated dust 22.000 5.000 0.000 1.440 0.580 0.100 0.001Injected prod 0.000 0.000 0.000 0.000 0.000 0.000 0.000Waste dust 3.810 5.200 0.000 11.230 2.073 0.493 0.255

Flow Ash Moisture S K2O (ash) Na2O (ash) Clt/h (as rec) % (as rec) % (as rec) % % % (as rec) %

Coal 8.680 10.460 5.570 1.020 2.100 0.290 0.000Coke 3.720 0.510 4.590 3.040 1.100 2.780 0.000

Flow SO2 Dust (dry) Dust SO3 Dust K2O Dust Na2O Dust Cl Loss of ignkg/h kg/h % % % % % *

Stack 908.18 0.00 0.00 0.00 0.00 0.00 0.00

Mass Balance

Flow CO2 Flow CO2=0dry t/h % t/h

Raw mix 168.5 35.4 108.83Recirculated dust 22.0 5.0 20.90Coal 8.2 - 1.13 ««| (Coal; Flow CO2=0: Ash + S converted to SO3 + Cl)Coke 3.55 - 0.30 ««| (LWF; Flow CO2=0: Ash + S converted to SO3 + Cl)Injected prod 0.00 0.00 0.00Total inlet - - 131.17Clinker 105.08 0.00 105.08Recirculated dust 22.00 5.00 20.90Waste dust 3.81 5.20 3.61Stack 1.14 0.00 1.135 (Stack; Flow CO2=0: Dust + SO2 converted to SO3 + Cl)Total outlet - - 130.72 ¯ Inlet-outlet: 0.44 (st/h LOI=0)

Flow Rate Adjustment

Weighting Flow Flow dry Flow CO2=0 Flow CO2=0 note - data entryt/h kg/kgkk t/h kg/kg kk • Enter weighting factors

Raw mix 0.50 168.2 1.60 108.61 1.03 in boldfaceRecirculated dust 0.00 22.0 0.21 20.90 0.20 • total must equal 1.0Coal 0.00 8.7 0.08 1.13 0.01 • all positive values 0-1Coke 0.00 3.7 0.03 0.30 0.00Injected prod 0.00 .0 0.00 0.00 .000Total inlet - - 130.94 1.24Clinker 0.50 105.3 1.00 105.30 1.00Recirculated dust 0.00 22.0 0.21 20.90 0.20Waste dust 0.00 3.8 0.04 3.61 0.03Stack 0.00 1.1 0.01 1.14 0.011Total outlet 1.0 - - 130.94 1.24

note - data entry on "Ignition loss"*Ignition loss at: %CO2 °C • Concerns LOI determination; impacts the CO2=0 mass balance

• if %CO2; LOI is only CO2 loss• if 1050; LOI is CO2 & moisture loss• if 1400; LOI is CO2 & moisture & volatile loss


6.24Rev. 2002

Kiln Audit November 1997Volatile Balance

kiln loadhypothesis

= 1.30 kg/kgclinkerSO3

Waste Dust=

4.063 17.304 31.362 Combustible=

5.154

Stack = 10.231

Return Dust=

Trapping = Volatilization =3.009 14.058 26.208

Raw Mix = 14.783 17.792 Kiln Load = 31.850 Clinker = 5.642

Total Trapping Coefficient=

0.544 Volatile Coefficient = 0.823

K2O

Waste Dust=

0.750 1.962 7.202 Combustible=

0.173

Stack = 0.000

Return Dust=





kiln loadhypothesis

= 1.30 kg/kgclinkerNa2O

Waste Dust=

0.178 0.387 8.615 Combustible=

0.028

Stack = 0.000

Return Dust=





Chlorine

Waste Dust=

0.057 0.059 1.275 Combustible=

0.018

Stack = 0.000

Return Dust=


Raw Mix = 0.095 0.097 Kiln Load =1.313 Clinker = 0.056




6.25Rev. 2002

8.6 Circulation in Preheater (Port-la-Nouvelle)

a. Kiln Parameters- Clinker production: 58.33 tph- Raw mix: 88.4 tph- Coal: 8.035 tph- Heat consumption: 833 kcal/kk- 2O kiln out: 2.5%

- 2O tower out: 3.5%

- Kiln exit gas: 1.286 Nm3/kk- C1 exit gas: 1.412 Nm3/kk- Tower exit gas: 1.505 Nm3/kk- Dust tower exit: 4.2 tph- Kiln exit temp: 1200 ºC- C1 exit temp: 835 ºC

• The dust from ESP and conditioning tower are mixed after the raw mix feeder.• In the following diagrams, the ESP dust + conditioning tower dust are called E-P dust.

b. Kiln Volatile Balance

SO3 K2O Na2O Cl

Volatilization (%) 68.5 77.5 18.4 99.0

Trapping (%) 100 100 100 100

c. Flow Calculation in Exchanger• Equation 1: @LOI=0 Mat C2 + Kiln dust = Mat C1 + C1 dust• Equation 2: [ ] [ ] [ ] [ ] 1212222 dustCCKdustC OKOKOKOK +=+

Cyclone Efficiency

C4

C3

C2

C1

95%

94%

94%

89%

d. Flux per Cyclone

Cl SO3 Na2OC1 Inlets

Outlets∂ rel

24.1525.61-6%

22.221.5+3%

2.782.84-2%

C2 InletsOutlets∂ rel

11.9211.4

+4.4%

8.0216.97-112%

2.272.58-14%

C3 + C4 InletsOutlets∂ rel

3.322.45

+23%

4.595.54-21%

1.511.74-15%

• The relative difference inlet/outlet is higher for the top stage:- only 1 measurement- smaller volatile content

• The 3SO balance for stage 2 is explained by the2SO trapping in material (lower in C1) 2SO is stable above700º. The volatile elements are trapped principally in the 2 bottom stages (75%).


6.26Rev. 2002

9. Lafarge Corp Typical Ratios

1998 data

Kiln by plant Rated Capacity Thermal load Specific loading Cooler loadingProcess Metric tonnes Gcal/hm2 MTPD/M3 MTPD/m2

Long wet Richmond 1 830 5.7 0.6 -Richmond 2 823 6.0 0.6 -

Woodstock 1 794 4.1 0.6 -Woodstock 2 839 4.4 0.6 -

Fredonia 1 446 3.4 0.5 22.3Fredonia 2 650 5.7 0.5 31.7

Paulding 1 687 6.1 0.6 22.8Paulding 2 687 6.1 0.6 22.8

Long dry Brookfield 1 650 4.1 0.5 25.1Brookfield 2 855 4.4 0.8 35.8

Exshaw 4 1272 3.5 0.5 34.6

Kamloops 617 4.0 0.6 23.8

St-Constant 1 1510 3.9 0.6 33.8St-Constant 2 1540 4.0 0.6 37.5

Alpena 19 1119 6.2 0.7 47.1Alpena 20 1105 6.1 0.6 32.2Alpena 21 1102 5.8 0.6 32.1Alpena 22 1649 5.1 0.5 34.0Alpena 23 1657 5.6 0.5 34.2

Joppa 1 1574 6.2 0.6 28.9

Sugar Creek 1 705 4.6 0.7 23.4Sugar Creek 2 804 4.7 0.7 22.3

Single stage Bath 3267 4.6 0.6 41.1Preheater

Joppa 2 1845 5.4 0.6 29.4

S Preheater Whitehall 1 1344 4.3 1.7 57.7Whitehall 2 947 3.7 1.8 52.4

AS Preca Exshaw 5 2459 5.3 4.1 57.0

Davenport 2751 2.7 3.4 40.0

Richmond 3 3000 3.1 4.7 38.9


6.27

10. 57 Clinker Reactivity Study (P. Barriac)Ranges studied: R. quartz on

63µ: 0.5% to5.3%

Sol. Na2O eq.:0.1% to 0.9%

Ex. SO3/tot. alk.: -0.6% to +1.7%

C3A perc.: 0% to12.6%

C3S perc.: 43% to76%

C2S perc.:2% to 31.5%

Free CaOperc.: 0.05%

to 2.2%

Underburningto

overburning

If we want:⇓

Siliceous rawmix reject

% of solublealkalies

Excess SO3/tot.alkalies

% of C3A % of C 3S % of C2S % of freeCaO

Moderateburning with:

�

R.1 or 2-d�

(easiercombination⇒: small aliteand belite size)

�

% alkaliesand/or clinker

% SO3 (to havea molar ratio

≥1)

�

(with Ex. SO3/totalalk. ≤1% to limit

alite size)

�

at the expense of%C4AF (strong

impact if high %sol. alk.)

�

at the expense of%C2S (and/or with�%C4AF and

%MgO)

�

in favour of%C3S

�

with � limesaturation

factor to keepC3S = Ct

� burningzone length

(in particular� rate of

temperaturerise)

�

R.28-d.�


�

% total alkalies(almost of allalkalies are

soluble at 28 d)

�


alite size)

�

at the expense of%C4AF

�

with �%C4AFand %MgO

�

with �%C4AF and

%MgO

(we can�free CaO to�

%C3S)

� burningzone length(� rates oftemperature

rise andcooling)

�

R. 1, 2 and 28-d.�


�


alite size)

�


�

with �%C4AFand %MgO

�

with �%C4AF and

%MgO

� burningzone length(� rates oftemperature

rise andcooling)

�

kWh/t�


�

(keeping a molarratio at least equal

to 1)

�


�

at the expense of%C2S (and/or with�%C4AF and

%MgO)

�

in favour of%C3S

� burningzone length

(inparticular�

rate oftemperature

rise)Note: To establish this table, we have taken all the results of the statistical study into account, plus some other results taken fromInfluence du Profilthermique – Comparison de 4 études de laboratoire– P. Barriac, June 6, 1995.Presentation: italics: explaining comments – normal letters: comments on application (method, limits).Clinker Reactivity – supplement to the 10 Basic Facts.

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