Process Guidlines

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Direction des Performances CimentiresProcess Group Leaders Network

Process Guidelines V3 October 2005Click to access the page

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Raw milling Raw millingPreheater Preheater Kiln KilnCooler Cooler Kiln and Cooler Filter Kiln and Cooler Filter Kiln by-pass system Kiln By-pass systemGas analyser Gas analyser Coal mill Coal millCement grinding Cement Gr Weighing-dosing Weighing-dosing

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Process guidelines - Contents -


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Back to table of contents

Process Guidelines V3 - October 2005

Best practice /recommendation

To be written

Specifications These are the figures we give to suppliers in the tender ; this column should contain the samefigures as other documents.

Alternatives In this column we describe alternatives, which could be accepted for cost reason, but also arenecessary for process reasons. Example would be cement mill specification is vertical mill,Alternative is ball mill and in case of a existing ball mill a roller press

Operating target Operating target is the range where we want to have an equipment operated; this is not to begiven to suppliers, but we will check offers accordingly. Important value for process evaluation ofexisting equipment or to calculate operation cost.

Not advisable These are choices we dont accept. Important if suppliers send alternatives on their own

Comments


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Raw milling Best Practice /Recommendation Specifications Alternatives Operating target Not advisable Comments


CHOICE OF MILL SYSTEM

Vertical Mill with cyclone andfan with VFD

Vertical Mill with cyclone andfan with VFD

2 compartments closed circuittube mills with drying

chambers (if moisture < 7-8%)orTube mills in combination withheated hammer crushers.High efficiency separatororRoller Press with Ball Mill

Tube mills without dryingchamber, or without external

drying.Autogenous Mills (only in caseof specific applications).Roll Press in circuit with V orVSK separator and/or dynamicseparator.Pregrinding circuit with two-compartments ball mill.Air Swept millCentral discharge mill

Modification of existinggrinding shop

Closed circuit millHigh efficiency separator

Closed circuit millHigh efficiency separator

Roll Press in circuit with V orVSK separator and/or dynamicseparator.Pregrinding with two-compartments ball mill circuit.Modification of 1st generationseparatorAddition of external dryingdrum

New Equipment Ball Mill with drying chamber

Mill Circuit Closed circuit Partial feed to the separator Open circuit

Ball mill speed 75% critical speed 75 % critical speed 78% critical speed

Ventilation ball mill

Air velocity above ballcharge=1,5 to 2,2 m/sinside the trunion: 22-25 m/sinside partition:8-14 m/s0,6 - 0,8 Nm3/kg raw mixhood < 5m/sdrop out box < 2m/sVFD fan

Air velocity above ballcharge=1,5 to 2,2 m/s

VFD fan

Mill L/D ratio1,5 < L/D < 3,2First compartment length = 3545% of mill total length

Process guidelines - Raw Milling - Page 1 / 3 06/10/2005 - 10:58


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Ball mill Liners

Moderate lifting liners for firstcompartment, classifying liners

for second compartment

Classifying liners in secondcompartment

Duo liftRipple liners

Without classifying liners keepa maximum of 3 - 4 ball sizes

Intermediate Partition wall

Central opening adapted tothe filling degree. Slots placedconcentricly. - 8 to 12 mm slotfor central partition.- open area > 50 % by centralopening

Diaphragms with material flowcontrol

Slots placed radially.

Outlet partition wall

Central opening adapted tothe filling degree. Slots placedconcentricly. Partition wall slotsize + 2mm (max slot = 0,5min ball size)

Slots placed radially.

Ball charge

Volume Loading:- for minimum kWh/t: 26-28%in C1 and 28-30% in C2- for max output: 32-34% inC1 and 34-36% in C2

Separator Third Generation HighEfficiency

Dust load < 1kg/m3Qf/Qa < 2.5

1st or 2nd generationseparators

Control

Fresh feed control to assureconstant feed to the separator.Mill controled by LUCIE.

Weighing rejects (beltweigher), measuring elevatorpower, mill presure loss, milloutlet temperature andelectronic ear.

Control mill fresh feed usingonly one parameter (onlyrejects flowrate or onlyelevator power , for example)

Fresh feed control can be doneby different ways, usingdifferent instruments or signals(rejects flowrate, elevatorpower, eletr. Ear, mill kW). It isrecommended to use them inconjunction.

Feed

Feed size 95%< 50 mmd80 feed < 20mm,

Precrushing, screening,external drying

The finer, the better

Drying compartment Moisture inlet C1 < 1.5%Specific drying capacity


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Equipment VRMVertical Roller Mill Recirculation of gas to the mill.

Metal detector and extractor inthe feeding line (after reject'sreturn)Gas flow measurement aftercyclone or filterWater injection systemCentral mill feed.HE SeparatorMaterial External RecirculationSystem >30% Fresh Feed

Capacity Fanwith VFDBed depth sensor

Metal detector and extractor in

the feeding line (after reject'sreturn)Bed depth sensorWater injection max 25 kg/tMaterial External RecirculationSystem >30% Fresh FeedCapacityFan with VFD

Water injection facilities in the

mill housing

Gas speeds:

Nozzle ring >30 m/sMill Body: 5 - 7 m/sSeparator: 3 - 5 m/sDust Load: 600 g/m3 at milloutlet

Feed device with triple flap

gate or rotary air lock valve,heated if wet or sticky rawmaterials.Fan max speed typical 700 rpmand >80% efficiency

Control Constant mill exit TConstant mill gas flowMill feed a to mill deltaP

Process guidelines - Raw Milling - Page 3 / 3 06/10/2005 - 10:58


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Preheater Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Equipment

Cyclones

5 Stage Preheater - lowmoisture < 5% raw materials

Low pressure drop

Bottom of cyclone> 50 height

No horizonatal inlet ; nohorizontal surface

4 Stage Preheater - highmoisture >5% raw materials

For a 5 stage PH, 4.5 to 5.5kPa (including kiln)

See priority study Preheater

Dip Tube Length relative tocyclone inlet height

Top (stage 1): 100%Stage 2/3: 75%minStage 4/5 : 50%min

Top (stage 1): 100%Hurrivanes - depending on

geometryNumber in % of inlet height

Splash box

Lafarge designcleaning devices. At least 55

to 80 between meal pipe andsplash box

2 m from flap, pipe withoutelbow

60 for kiln feed to splash box.

>60 o below C3 Splash plates See priority study Preheater

Pendulum flap External knife bearing

Precalciner Vessel + Hot core preferredResidence time > 6 secfor petcoke, Low-Nox

Residence time > 6 sec Riser Duct plus hot core Very specific to fuel and plantconditions

Tertiary air duct

Downward split designfor in-line calcinerDamper control

Duct velocity 20 to 30 m/s

Process

Gas duct velocity at mealentrance

Mini 12 m/s top stagewith 17 m/s bottom

(intermediate proportional)Can install restriction

as alternative

Riser velocity 16 m/s minimum

Process guidelines - Preheater - Page 1 / 2 06/10/2005 - 10:58


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Preheater Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Cyclones Top cyclone efficiency > 95% Top cyclone efficiency > 95%

Meal curtain

Considered if high volatilecycles expected

Most common on N-1 stageon kiln side

LateralConsider a splitter

Kiln inlet box

No dead zoneSmooth design (entrance in the

middle)No turbulances

45- 50 slope of inlet

Downcomer

Cooling by water spraysMinimum evaporation: 4 sec

(for target at 185C)No bleed air is recommended,

except for start up

Water design target able toprovide 185 C. Take careabout moisture in gas to coalmill take off above waterinjection

ID fan preheaterVFD drive

Fresh air intake beforethe fan (fan protection)

Fan Typical Max speed 990rpm and efficiency >80%.Design margin 5% volume and1 kPa pressure

number of fans3

ID fan, raw mill fan &baghouse fan

Only 2 fans

Secondary Fuelusage

Burner preferred for Calciner

Process guidelines - Preheater - Page 2 / 2 06/10/2005 - 10:58


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Kiln Best Practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Equipment

Burner type and position Lafarge BurnerMAS burner in case of regularsolid fuel and alternative fuel ;

Position in center line of kilnand aligned on kiln axis (only

if kiln is stable and burnerhaving sufficient impulse)

See Lafarge Burner DesignSpreadsheet

Fuel speedSolid Fuel: 25 - 35 m/s inburner ; >25m/s in conveyingline

Solid Fuel: 25 - 35 m/s inburner ; >25m/s in conveyingline

Alternative Fuel: 25 - 40 m/sin burner ; >25m/s inconveying line

Total primary air 25 cStSwirl Design: 0,15

Impulse Design: >2,2Final design criteria to beworked out.

Retaining rings0,6 to 1 m from nosering assingle ring, triangulkar shape

Double flat barMaggoteaux system

Kiln slope 3 - 3,5 % 4%

L/D

>10,5 for preca (> 15 isrequired when designing foralternaitve fuels)> 15 for preheater

Tertiary air

From kiln hoodTake off velocity 5-6 m/sthroat and tertiary air and 25m/s in the duct

From kiln hoodTake off velocity 5-6 m/sthroat and tertiary air and 25m/s in the duct

Settling chamber Heat shield IKN not proven

Shell cooling fans 12 to 18 m/s at shell SuppliedFan should be below kiln sothat air flow comes up onboth sides.

Process guidelines - Kiln - Page 1 / 2 06/10/2005 - 10:58


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Kiln Best Practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Process

Thermal load< 5 MW/m (kiln cross

section)< 5 MW/m < 6.5 MW/m

Limit for refractory.Some wet and big kilns canoverpass the limit

Kiln hood velocity < 6 m/s

Kiln load


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Cooler Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

EquipmentEquipment Selection Cross Bar or Walking Floor

DesignCross Bar or Walking FloorDesign

Grate load < 45 t/m d < 45 t/m d

Variable speed fans All on 1st grate Variable speed on all on 1stgrate fans. 2nd grate fans canbe with variable inlet vanesdampers

Fan dampers (inlet radial) Flap max speed typical 1500 rpm,Efficiency > 80%. Normally 20-30% pressure reserve.

Fix inlet rows 5 to 8 (1.5 - 2.5 m)Max 15 degree angleRefractory HorseshoeAir Cannons

Crusher Roller crusher intermediateor at the end

HammerCrusher

Hammer crusher can be thefirst choice if no need for veryeffective cooling

Grate slope 0 3 maximum

Evacuation hoppers Simple gate and sensor level Double gate mechanicallyactivated

ProcessAir flow design Not < 2,1 Nm3/kg > 2.1 Nm/kg ck

> 1.7 Nm/m/s on first fans, 2Nm/m/s for KIDS

First fans pressure > 10 kPa (100 mbar) for KIDS

Optimal bed depth Lowest stroke permitted with20% reserve on fans(6-8 st/min for properlydesigned cooler)

Air velocity above clinker 5 to 7 m/sClinker transport design Min. 1,5 x nominal capacitysteel conveyor

Min. 1,5 x nominal capacitysteel conveyor

Process guidelines - Cooler - Page 1 / 1 06/10/2005 - 10:59


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Kiln filter Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Equipment

Equipment SelectionLow Pressure Pulse Jet Bag

Filter ( 2,5 bars)

Low Pressure Pulse Jet (LPPJ)

Bag Filter ( 2,5 bars)

High Pressure Pulse Jet (HPPJ)Bag Filter (6bar/100psi),Electrostatic precipitator

Max dP< allowed by fancapacity at end of bag life.

Limit cleaning cycles to obtaintarget bag life.

Off line cleaning is notacceptable due to thepotential damage to the bags.

BH sizing must maintainoperating pressure drop withinthe limits of the ID fan and thepulse jet filter ability to cleanbag on line.

Equipment SizingGross Air to clothe ratio:1m/min average1.3 m/min max (upset cond)

Gross Air to clothe ratio:1m/min average1.3 m/min max (upset cond)

Bag quality

Fabric with PTFE membraneand fiberglass structure.Known suppliers: Gore, BHA,Tetratec workingat 180C- 230C max

Design temperature 230CPeak temperature 260C

P84 bags of suitableconstruction.

Adequate temperature controlto prevent teflon and SGTevaporation and bag damage.working at 180C- 230C max

Other bag materials that arenot proven.If using P84 verify the risk ofhydrolysis.

Bag quality and workmanshipare critical. Bag to cage fit iscritical.

Airflow DistributionScale model to ensure goodairflow distribution and correct

fan sizing before purchase

Compressed Air SupplyAir coolers can be acceptablefor LPPJ.

Use air dryers (dessicant) forHPPJ (-30deg C due point).

Prevent moisture condensationin the bag during thecompressed air pulse.

No oil in cleaning air.

Exhaust Fan VFD VFDFan Typical Max speed 990rpm and efficiency >80%.Design margin 15% volume

False AirDirect < 30% Preheater GasesCompound < 50% PreheaterGases

Process guidelines - Kiln and Cooler Filter - Page 1 / 2 06/10/2005 - 12:08


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Kiln filter Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

COOLER FILTER

Equipment SelectionAir to air heat exchanger to

get 130C at exit

Air to air heat exchanger to

get 130C at exit

Common baghouse forRM/kiln and cooler

ESP when all cooler gas usedfor raw materials drying

Exhaust system capacity tohandle normal operation andto provide sufficient capacityfor push conditions for the fulllength of the bag life.

Gas flow in BH hopper mustnot cause abrasion of filterbags due ro high velocities.

Exhaust gas flow from thecooler straight entry andoriented downwards throughheat exchanger

Gas velocity at heatexchanger's inlet in normalconditions: 80%.Design Margin 15% volume

System SizingDesign upset conditions 450 Cexhaust gas temp. Designflow 1.7 nm3/kg clinker

Design upset conditions 450 Cexhaust gas temp. Designflow 1.7 nm3/kg clinker

Process guidelines - Kiln and Cooler Filter - Page 2 / 2 06/10/2005 - 12:08


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Kiln By-pass system Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Equipment

Dedusting Bag filters (240C) ESPWet scrubber may be asolution when cement Cl is alimitation

Dust transport As short as possibleMechanicalAir transport if Cl < 10%

StorageAs small as possible,

with mechanical extractionDirect dust addition to cooler

filter or heat exchangerintermediate storage

Addition to cooler only ifclinker storage does not

promote segregation (quality -dust separation in pile)

Process

Location take-off

On top of the smoke box, on

the kiln sideDistant from C3 discharge to

avoid dust mixing

Level of chlorine in dustDilution with kiln feed if >

10% ClCl control using cyclone system

with bypass (Taiheyo)

Quenching

Air quenching as close aspossible to the take out, eitherdirectly to 200C or at least to

400C

Air to air cooler as secondcooling step to minimize the

gas quantity

Exhaust airTo cooler fans to avoid

SO2/Dioxins

Raw mill or main stack if SO2 isacceptable, dioxins still a

threat. Detached plume also apotential issue if organics in

raw mix

Separate stack

Dust managementCement (limiting factor forClas allowed by local standard)

Clinker (limiting factor for Cl)Dust Washing with heavy

metal recovery, for low limit ofCl in cement

Dust wasting

Target level of chlorine in kilnback-end mat

1,00%Higher concentration

acceptable if possible for build-ups

Process guidelines - Kiln By-pass system - Page 1 / 1 06/10/2005 - 10:59


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Gas analyser Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Kiln inletKiln inlet

Probe

Probe long enough to enterthe kiln, retractable,

motorisedDry probe requiredWater cooled jacket

Same probe for all gasesBack flush (clean, dry air)

Oil cooledIn-situ

COMandatory

Type: IRScale: 0-20000 ppm

NOx

MandatoryType IR

No NO2 converter neededScale: 0-20000 ppm

O2Mandatory

Type: Paramagnetic0-10%

SO2

Required if Total SO3 input >1.2% on clinker basis or

S/A ratio > 1.2Type UV

Quartz cells

0-20000ppm

IR (on separated line)

Gas treatment

Heated line (>180C)2 cooler dryer 1 for SO2 and 1

for other gasesFor other gases H2O2 injection

Suspension preheater kiln - no PC

Exit of preheater tower Mandatory for O2 and CO

Exit of PrecalcinerPrecalciner

Probe

Probe at Bottom cyclone exitretractable,

Dry probe requiredWater cooled jacket

Same probe for all gasesBack flush (clean, dry air)

Process guidelines - Gas analyser - Page 1 / 2 06/10/2005 - 11:02


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Gas analyser Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

COMandatory

Type: IRScale: 0-20000 ppm

NOx

MandatoryType IR

No NO2 converter neededScale: 0-20000 ppm

O2Mandatory

Type: Paramagnetic0-10%

Gas treatment

Heated line (>180C)2 cooler dryer 1 for SO2 and 1

for other gasesFor other gases H2O2 injection

3 other in line O2 last

CEM (stack)Location Follow local regulation

Dust Scattered light system

O2In-situ system (Zircon)

0-10%

H2OOptical in-situ system IR

0-10%CO

Optical in-situ system IR0-2000 mg/Nm3

Extractive with heated probeand line (>180C) + FTIR

NOxOptical in-situ system-UV

0-2000 mg/Nm3Extractive with heated probe

and line (>180C) + FTIR

SO2Optical in-situ system-UV

0-500 mg/Nm3Extractive with heated probe


HClOptical in-situ system-IR

0-100mg/Nm3Extractive with heated probe


COVExtractive FID

0-200mg/Nm3CO Protection with ESP

Precalciner KilnUse precalciner exit CO withpreheater exit CO as back up

Suspension preheater kilnUse kiln exit CO with

preheater exit CO as back up

Process guidelines - Gas analyser - Page 2 / 2 06/10/2005 - 11:02


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Coal Mill Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Equipment

Equipment Selection Vertical mill Vertical mill

Ball mill ,

Ring roller millsPendulum mills

Central discharge mills"deep bowl" mills

Ball mills are better suited forvery hard fuels and certain

cokes. Also need to considerturndown ratios if AF issignificant - need VFD orsomething appropriate.

Process GasHot gas from pre heater withde dusting

Hot gas from pre heater withde dusting

Direct or semi direct firing

Sensors

CO analysers:- Raw Coal Bin- Mill Filter Exit- Each Pulverised Fuel Bin

O2 analysers:- Preheater Exit- Before Mill- Mill Filter Exit

Temperature sensors- Raw coal hopper/silo

- Before mill- After mill- Hot gas duct- Filter bottom- Coal dust after filter- PF silo bottom ( In banks offour around cone)- Differential temperatureacross filter

Differential temperature acrossseparator for ball mill

Load Cells- Raw Coal Bin- Pulverised Coal Bins

Pressure indication- Before mill- After mill- Mill differential pressure- Filter differential pressure

Dust monitor- Coal bag filter main stack

Process guidelines - Coal mill - Page 1 / 2 06/10/2005 - 11:00


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Cement Grinding Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Equipment

Equipment Selection Vertical Mill Vertical Mill

Roller PressPregrinding circuit with two-

compartment ball millcircuit.CKP with 2compartment mill,Ball mill

Ring roller mills,central discharge mills

Ball Mill CircuitClosed circuit mill withseparate filter for millventilation and separator

Ball mill

Single compartment withlifting and classifying liners*2,8 < L / D


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Cement Grinding Best practice /Recommendation Specifications Alternatives Operating target Not advisable CommentsBack to table of contents

Ventilation separatorSeparator Qf/Qa:1.8 kg/m,VFD fan for HES,

The circulating load 200%

Separator Qf/Qa:1.8 kg/m,VFD fan for HES,

The circulating load 200%

Separator Qf/Qa range: 1.8-2.5 kg/m3(200% C.L), Cementtemp 90-110 deg ,VFD for fan

Final product load32% ball charge

Higher filling causes higherspecific energy, problems forcooling. Ball charge withpregrinder needs to bemodified

Process

Control

Pre requisites for Lucie - Freshfeed variation throughweighing of separator rejects,feed accuracy with in +/- 1%,electronic ear to detect fillingof first compartment.

Belt weigher for rejectsElevator power

FeedFeed size passing on100%


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Weighing Dosing Best Practice /Recommendation Specifications Alternatives Operating target Not advisable Comments


Pulverised Coal

Equipment Selection

Small bins close to the burningpoint 40 m. Actual limit

is back pressure. Long distancemeans more backpressure butcan be compensated for byproper design. Schenk Starfeeder with high pressure

transport line notrecommended (low tolerance).

Schenk Coriolis + BremerScrew + FK pump for long

distance is very good.

Velocity Minimum number of elbowsvelocity >= 25 m/sMinimum number of elbows

velocity >= 25 m/s

Solid concentration 4-6 kg/nm3 4-6 kg/nm3 > 7 kg/nm3

Raw meal

Equipment Schenk Coriolis

PfisterWeigh Feeder

Both still recommend level binahead of scale to minimize siloflushes. Using airlift pressure to

calculate flow can be

sufficiently accurate.

Effective weighing Variation < 0,5 % (short term) Variation < 0,5 % (short term) Accuracy < 0,5 % (short term)

Transport Elevator Elevator Air-lift

Process guidelines - Weighing-dosing - Page 1 / 1 06/10/2005 - 11:05

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