Residence time in Kiln “t” = 1.77 (Phy)^1/2 L

________________

Alpha* D*N

Phy =Angle of repose for lime stone

~ 36 Degree

L = length of Kiln in meter

Alpha = Kiln inclination in %

D = Effective diameter of Kiln in meter

N = Rotation per minute rpm

Precalcination Zone = 2 min

Calcination Zone = 10-12 min

Burning Zone = 6 – 8 min

Cooling Zone = 2 min

Preheater Zone = 1 min A

B

C

D

F

=

t = 20 -28

Minutes

B C DA E

Kiln

Inlet

Kiln

Outlet

7.5m/sec

Mat velo Max

4.5m/sec

Mat Velo Min

12 CaO

Lime stone

2 SiO2

Silica oxide

2 Al2O3

Aluminium oxide

Fe2O3

Iron oxide

1450*C

3Cao.SiO2 (C3S)

Alite

2CaO SiO2 (C2S)

Belite

3 CaOAl2O3 (C3A)

Tricalcium Aluminate

4CaO.Al2O3.Fe2O3 (C4AF)

Tetra Calcium Alumino Ferrite

CLINKERISATION

100* CaO

LSF =

(2.8 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3)

0.66 > LSF < 1.2

= =

LIME SATURATION FACTOR

AR = > 0.64

SiO2

SR =

(Al2O3 + Fe2O3)

2.2 > SR < 2.6

= =

SILICA RATIO

Al2O3

AR =

Fe2O3

1.5 > AR < 2.5

= =

ALUMINA RATIO

AR < 1.5 IS CALLED FERROCEMENTS

AR = 0.637 IS CALLED FERRARI CEMENT

CALORIFIC VALUE OF COAL

LHV = HHV – 50.1H – 5.6 M – 0.191O

H = % HYDROGEN M = % MOISTURE O = % OXYGEN

LHV = LOW HEATING VALUE Kcal /Kg

HHV = HIGH HEATING VALUE Kcal /Kg

KCal / Kg x 4.187 x 10^(-3) = MJ/Kg

KCal / Kg x 1.8 = Btu / lb

ultimate

analysis

COAL USED IN CEMENT INDUSTRY

• LHV = 6500 – 7000 Kcal / Kg

• ASH = 12~15 %

• VOLATILE MATERIAL = 18~ 22 %

• MOISTURE = UP TO 12 %

D =Diameter in

Meter

L = Length in meter

WEIGHT OF CYLINDRICAL( kiln) SHELL = W

W = Pi x (L) x (D) x thk (mm) x 7.85 Metric Tons

THERMAL EXPANSION OF SHELL

A = Alpha x T x L

Alpha for steel (coefficient of linear expansion = 1.2x 10^ (-5)

mm per Meter

T= dT =( Average temp – Ambient temp) Degre centigrade

L= Length of (Kiln) Shell

=L1 + L2

T2a

T2bb

T1

A1= (T2a+T1)/2 - T

A1= (T2b+T1)/2 - T

Ambient temp = T

Skin Temperature

Diagram

L1 L2

A = A1 +A2

X L1

X L2

KILN SPECIFIC VOLUME LOADING = TPD/ m3or Specific Kiln capacity ~ 2.3 t / m3 at Kiln circumferential

speed = 50 cm / sec

KILN SPECIFIC THERMAL LOADING = Kcal / m2.hr

Specific Kiln thermal loading Qp = 1.4 x 10 ^ 6 x D Kcal / m2. hr

Qp should not exceed 3.46 x 10^6 Kcal/m^2.hr

COOLER SPECIFIC LOADING or Specific Cooler Capacity =

TPD/ m2 = 38 -43 metric ton of clinker per m^2 .24 hr

IMPOTANT PARAMETERS

KILN % FILLING = 04 % Min - 16% Max

KILN CAPACITY ASSESMENT

•Capacity of ID fan.

•Preheater cyclone design.

•Proclaimed Design & Volume.

•Kiln inclination & Volume.

•Kiln % filling, Specific volume loading &.Thermal

loading.

•Kiln Drive capacity.

•System Design, Ducts, GCT, fan position & ESP.

For Gears:

Pitch Diameter = Module x No. of Teeth

Blank Diameter = Module x (No of Teeth+2)

For Airslide Cloth

• Fabric Polyester 100%.

• Min=140*C & Max = 260*C.

• Permeability = 400m3/hr-m2 or 6m3/min-m2. at 80mbar

• Tensile strength : WEFT = 1200 Kg/cm2 : WARP = 600 Kg/cm2

• Air Required = 2.5-3.0(Closed type), (2 Cone silo Bins),(1.5Open

Type)

VVI

V

IV

III

II

IA IB

Twin cyclonesTwin cyclonesPH fan-1 PH fan-2

Riser

Duct

KILN

Girth gear

SLC

T.A.Duct

I II III

950*C

PYRO STRING

KILN STRING

CEMENT MILL FORMULAS

MILL CRITICAL VELOCITY = 76 / (D)^1/2

MILL ACTUAL VELOCITY = 32 / (D)^1/2

H

D

MILL CROSS SECTION

H = 0.16D

Mill charging:

Dynamic Angle of Repose = 35 degree 20 minutes with Horizontal (Theta )

Theta

OR

Dynamic Angle of Repose = 54 degree 40 minutes with Vertical (Theta )’

Theta’

GRINDING MEDIA LOAD “ G”

G = 4620(R)^2.L

TAGGARTS FORMULA

Sy = specific gravity of

ball 7.8-7.9 Ton / m3

gm = Bulk density of charge

4.5 Ton / m3.

Pi = 22/7 or 3.14

Constants:

G = gm.Sy.Pi. (R)^2.L

4

POWER CONSUMPTION OF MILL = P

P= 12G

SEPARATOR

A %fines/F

B%fines/D

C%fine/G

A % fines of separator feed

B % fines of Tailings/Reject

C % fines of finished Product

F TPH of separator feed

D TPH of Tailings/Reject

G TPH of finished Product

s

Ball Mill

Seperator efficiency

n = C (A-B)

A(C-B))

L= G/D=A-C

B-A

F = L(1+D)

1.

2.

3.

L / D = 3 Two Compartment Mill

L / D = 4.5 Three Compartment Mill

Carman Lining

Slegton –

Magotteaux

LiningLining

FLS Lining

Classifying

Liners

I – Chamber Drag Peb Liners

Important Conversions

1 Barrel = 42 Gallons = 159 litres = 5.615 Cuft

1 Kcal = 4.187 J KCal / Kg x 1.8 = Btu / lb

Characteristic OPC-43(IS8112) OPC-43(IS12269) PPC- (IS1489)Part-1

Blaine 225 225 300

3 Days(MPa) 23 27 16

7 Days 33 37 22

28 Days 43 53 33

70 *

H

L

L=H/2

Length of Dip Tube = ½ Gas inlet height Single Stream

ESP ELECTROSTATIC PRECIPITATOR

GASCONDITIONING TOWER SPRAY

TOP VIEW

SIDE VIEW

Kiln Data :

4.4 meter Diameter x 60 meter length

Inclination = 3.5%

Shell thicknesses = 25 mm , 28 mm , 35 mm , 65 mm

Kiln speed = 3.5 to 5.25 RPM

Preheater : Type : 6440 / PR 7044 VI Stage

2200 m

3500 m

2000 m

3200 m

Dip tube

(Diameter)

4400 m

7000 m

4000 m

6400 m

I Cyclone Twin

(Diameter)

Pyro stringKiln stringDesc

Girth Gear :

Module = 39

No of Teeth = 148

Material of construction = CS 640 (Normalized Cast Steel)

Dimensions = 550 mm (width)

Pinion :

Module = 39

No of Teeth = 28

Material of construction = 30 Cr Ni Mo V8 (Normalized CastSteel)

Dimensions = 600 mm (width)

Tyre Assemblies three no’s :

Material of construction = GS 24 Mn 5 (Normalized Cast Steel)

Dimensions = 5620 OD x 4581 ID x 775 (width)

Supporting Rollers Assemblies three no’s :

Material of construction = CS 640 (Normalized Cast Steel)

Dimensions = 5620 OD x 4581 ID x 775 (width)

Main Drive

Tyre

Supporting Roller

Girth Gear

Pinion

Kiln

Shell

Kiln Main Drive : Gear box = SDN 800

Ratio = 54.35:1

Motor KW = 710

Input RPM = 100 - 1000Aux G.B SDA 250 54.35: 1

Motor 30 KW ; 1500 RPM

MotorG.B

Kiln Axis

G.G

Pinion

Motor G.B

RWN-500

Concord Alingnomatic

Geared Coupling

RWB-178

MID KILN

FEEDING

Degree Of Kiln filling & Kiln Cross Sectional loading:

% of Filling or

Kilns Degree

Area of this segment (A1)

=Area of cross section of Kiln (A)

Segment

Theta

4.570

5.4275

6.5280

7.7585

9.0990

10.795

12.1100

13.75105

15.65110

% of Kiln

filling

Centric Angle Theta

(Degree)

r^2

2

O – Sin OA1 =

r = radius inside lining

A = II r^2

131211109

2.03.03.54.04.5Theta

%

Note : In practical Kiln operation the kiln load should not exceed

13%,since higher Kiln loads impair the heat tranfer

Rotary Kiln Slope versus Load

Thumb rule by Bohman

> 3.4 m3

3 m to 3.4 m4

up to 2.8 m5

Kiln diameter

(m)

% Kiln

Slope

Material velocity in kiln

1). Burning Zone = 4.5 mm / sec Lowest

2). Calcining Zone = 7.5 mm / sec Max

Rotary Kiln power input calculation :

W x bd x td x N x F x 0.0000092

rdH.P =

W = Total vertical load on all roller shaft bearing,lb

bd = roller shaft bearing diameter , inches

rd = roller diameter , inches

td = tire or riding rind diameter , inches

N = rpm of Kiln shell

P = Coefficient or friction of roller bearings , 0.018 for oil

lub bearings & 0.06 for grease lub bearings

1

This is Frictional

Horse Power 1

Note :

This is Load Horse

Horse Power2

(D x Sin O) ^3 x N x L x KH.P = 2

D = Kiln dia .inside lining , ft

Sin O = read from diagram depending on %Load

N = rpm of Kiln shell

L = length of kiln in ft

K = 0.00076 Total power = 1 2+

Arun Shourie

Relation Manager - Insurance

Dir: +91 (22) 4086 3835 / +91 99200 29366

Cement Monthly - Edelweiss

From: Arun Shourie [mailto:Arun.Shourie@edelcap.com]

D

d

L

v

H

Burner Pipe

Location40*

Burner pipe centering location and alignment

Kiln Diameter = D

Kiln lining thickness = a

Kiln Coating thickness = b

Angle of Repose of kiln load = O = 40* say

Kiln Load = K % Value from table below

Depth of bed in Kiln = Y % To be measured

D – a – b

2

X K % = Z

V

=

ZCos O

H Z= SineO

2119.81.8.817.716.715.614.513.412.2119.75

Depth of

material bed in

Kiln = Y %

15141312111098765Kiln load = K %

Standard Coal Factor : SCF

To determine the approximate combustion air needed to burn

a given unit wt of coal, formula given below can be used when

no ultimate analysis is available. The combustion air

requirement include here 5% of excess air

100 - a

100

B

7000= SCF

a = % Moisture in coal ( as fired )

B = Heat value of coal ( Kcal / kg as fired )

Kg of Air

Kg of Coal

= 10.478 SCF

% Loading of Kiln :

C x f x t

d x VL =

C = Capacity of Kiln Ton / hr

f = Ton (Kg) dry feed / Ton ( kg) of Clinker

t = residence time

d = Bulk density of dry feed ton (Kg) / m^3

V = Internal volume of kiln in m^3

Theoretical Flame

Temperature fuel oil :

TQ

Vg x Cp=

Q = heating value of

oil , K cal / kg

Vg = Volume of

combustion gases ,

Nm^3 / Kg

Cp = Specific heat of

combustion gases

=0.40 at 2000*C for

fuel class “S”

Rotary kiln Capacity

Martin’s Formula :

C = 2.826 v

Vg

C = Kiln Capacity Ton / Hr

V = Gas Velocity in gas discharge end , m / sec

Vg = specific gas volume , m^3 / kg clinker

X D^3

D = Kiln Diameter on Bricks, m

Heat capacity of Rotary kiln

Q = 1.1 x 10 ^ 6 x D ^3 (Kcal / hr)

D = Mean inside Kiln Diameter on Bricks, m

Kiln Thermal loading at cross

section of burning zone = Qp =

1

2

= Q / Fp

Fp = 0.785 x D^2 Inside cross-section of the kiln

burning zone m^2 where D is kiln shell diameter

Q p = 1.4 x 10 ^ 6 x D Kcal / m^2.hr

Qp should not exceed 3.46 x 10 ^ 6 kcal / m2.hr

Heat transfer in cyclones preheater:

The rule is that the sizes of the gas ducts and of the

cyclone should be in accordance with the formula:

V ^ 2

ID ^ 5= Constant

V = Gas volume

ID = Inside Diameter of ducts /

cyclones respectively

Preheater cyclone sizing

(V) ^ 2 x Vt CP4D = 0.536

D = cyclone Diameter , m

Vt = sp. gr. of gas at aver. Temp , Kg / m ^ 3

V = Gas volume passimg cyclone , m ^ 3 / Sec

C = Coefficient for pressure drop = 110

P = Pressure drop in cyclone in mm WG

Vt = V0 273 + t + K273

K = dust concentration in

Gas , grams / m^ 3

70 *

H

L

L=H/2

Length of Dip Tube = ½ Gas inlet height Single Stream

Small size high efficiency cyclone

Pressure drop across cyclone = 55 – 60 mbar

Theoretical Heat consumption for

clinker burning :zur Strassen formula :

1.40.592.31Fe2O3

1175.1122.68SiO2

18.85.863.2H2O

488.77.64663.91CaO

6.86.481.05MgO

13.12.225.92Al2O3

kcal/kgFactor YX %Name

Heat ConsMultiplicationConstituentConstituent

+

+

+

+

_

_

527.4

+

Net

118.4

_

Net % 99.27 Net Kcal / Kg = 409.0

6.48*MgO

Q = 2.22 Al203 + 6.48 MgO + 7.646 CaO + 5.86 H2O + 5.11 SiO2 + 0.59 Fe2O3

Q

Thermal efficiency of cooler = E

A - B

A

X 100E =

A = Heat loss of clinker leaving the kiln

B = Heat loss of the clinker cooler

Secondary Air Temperature = t3250 (347 – K )

( X . n )=

K = Heat loss of the cooler , Kcal/Kg clinker

X = Specific Heat consumption of the kiln , Kcal / Kg clinker

n = Excess Air number = 1.1

Cooler fans designed for Specific Volume of 3 – 3.15 st.m^3/Kg clinker

Cooling of kiln Exit Gases (GCT)

YKg / min.Exit gas x 0.25 ( t 1 – t 2) Kcal / min

H t 2 – H t 3

=

t1 = Temperature of Kiln exit gases

t2 = Temperature of gas to be achieved or maitained

t3 = temperature of water (15*C)

H t2 = Heat content of water at t2

H t3 = Heat content of water at t3

Y = Kg Water Spray / min