This contains critical practical formulas for Kiln Performance in comparision to

1. 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

2. Kiln Kiln
Inlet Outlet
A B C D E
Preheater Zone = 1 min A 7.5m/sec
Mat velo Max
Precalcination Zone = 2 min B
t = 20 -28
= Minutes
Calcination Zone = 10-12 min C
Burning Zone = 6 – 8 min D
4.5m/sec
Cooling Zone = 2 min F Mat Velo Min

3. CLINKERISATION
12 CaO 3Cao.SiO2 (C3S)
Lime stone Alite
2 SiO2 2CaO SiO2 (C2S)
Silica oxide Belite
1450*C
2 Al2O3 3 CaOAl2O3 (C3A)
Aluminium oxide Tricalcium Aluminate
Fe2O3 4CaO.Al2O3.Fe2O3 (C4AF)
Iron oxide Tetra Calcium Alumino Ferrite

4. LIME SATURATION FACTOR
100* CaO
LSF =
(2.8 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3)
0.66 > LSF < 1.2
= =
AR = > 0.64

5. SILICA RATIO
SiO2
SR =
(Al2O3 + Fe2O3)
2.2 > SR < 2.6
= =

6. ALUMINA RATIO
Al2O3
AR =
Fe2O3
1.5 > AR < 2.5
= =
AR < 1.5 IS CALLED FERROCEMENTS
AR = 0.637 IS CALLED FERRARI CEMENT

7. CALORIFIC VALUE OF COAL
LHV = HHV – 50.1H – 5.6 M – 0.191O
LHV = LOW HEATING VALUE Kcal /Kg
HHV = HIGH HEATING VALUE Kcal /Kg
M = % MOISTURE H = % HYDROGEN O = % OXYGEN
KCal / Kg x 4.187 x 10^(-3) = MJ/Kg ultimate
analysis
KCal / Kg x 1.8 = Btu / lb

8. COAL USED IN CEMENT INDUSTRY
• LHV = 6500 – 7000 Kcal / Kg
• ASH = 12~15 %
• VOLATILE MATERIAL = 18~ 22 %
• MOISTURE = UP TO 12 %

9. 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

10. THERMAL EXPANSION OF SHELL Skin Temperature
Diagram
A = Alpha x TxL L= Length of (Kiln) Shell
=L1 + L2
Alpha for steel (coefficient of linear expansion = 1.2x 10^ (-5)
mm per Meter
T= dT =( Average temp – Ambient temp) Degre centigrade
L1 L2
A1= (T2a+T1)/2 - T X L1
T2bb
A1= (T2b+T1)/2 - T X L2 T1
Ambient temp = T T2a
A = A1 +A2

11. IMPOTANT PARAMETERS
KILN SPECIFIC VOLUME LOADING = TPD/ m3
or 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
KILN % FILLING = 04 % Min - 16% Max

12. 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.

13. 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)

14. PH fan-1 Twin cyclones PH fan-2 Twin cyclones
IA IB
II
III
IV
Riser
Duct
V KILN STRING
VI
V
950*C
T.A.Duct
SLC
PYRO STRING KILN
I Girth gear II III

15. CEMENT MILL FORMULAS
MILL CRITICAL VELOCITY = 76 / (D)^1/2
MILL ACTUAL VELOCITY = 32 / (D)^1/2

16. D Theta’
Mill charging:
Theta
H
H = 0.16D
MILL CROSS SECTION
Dynamic Angle of Repose = 35 degree 20 minutes with Horizontal (Theta )
OR
Dynamic Angle of Repose = 54 degree 40 minutes with Vertical (Theta )’

17. GRINDING MEDIA LOAD “ G”
G = gm.Sy.Pi. (R)^2.L
4
Constants:
Sy = specific gravity of
G = 4620(R)^2.L ball 7.8-7.9 Ton / m3
gm = Bulk density of charge
TAGGARTS FORMULA 4.5 Ton / m3
.
Pi = 22/7 or 3.14

18. POWER CONSUMPTION OF MILL = P
L= G/D=A-C
2.
B-A
P= 12G
SEPARATOR
B%fines/D
A %fines/F
Seperator efficiency
A % fines of separator feed s
B % fines of Tailings/Reject C%fine/G
C % fines of finished Product
F TPH of separator feed
D TPH of Tailings/Reject
G TPH of finished Product
Ball Mill
1.
n = C (A-B) 3.
A(C-B)) F = L(1+D)

19. L/D=3 Two Compartment Mill
L / D = 4.5 Three Compartment Mill
I – Chamber Drag Peb Liners
Carman Lining
Classifying Slegton –
Liners Magotteaux
Lining
Lining
FLS Lining

20. 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

21. L
H
70 * L=H/2
Length of Dip Tube = ½ Gas inlet height Single Stream

24. ESP ELECTROSTATIC PRECIPITATOR

25. TOP VIEW
GASCONDITIONING TOWER SPRAY
SIDE VIEW

28. 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
Desc Kiln string Pyro string
I Cyclone Twin 4000 m 4400 m
(Diameter) 6400 m 7000 m
Dip tube 2000 m 2200 m
(Diameter) 3200 m 3500 m

29. 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)

30. Tyre Assemblies three no’s :
Material of construction = GS 24 Mn 5 (Normalized Cast Steel)
Dimensions = 5620 OD x 4581 ID x 775 (width)
Main Drive
Supporting Rollers Assemblies three no’s :
Material of construction = CS 640 (Normalized Cast Steel)
Dimensions = 5620 OD x 4581 ID x 775 (width)
Tyre Kiln
Supporting Roller Shell
Girth Gear
Pinion

31. Kiln Main Drive : Gear box = SDN 800
Ratio = 54.35:1
RWN-500
Motor KW = 710
Aux G.B SDA 250 54.35: 1 Input RPM = 100 - 1000
Motor 30 KW ; 1500 RPM
Motor G.B
G.B Motor
RWB-178 Pinion
Kiln Axis
Concord Alingnomatic
Geared Coupling
G.G

34. MID KILN
FEEDING

36. Degree Of Kiln filling & Kiln Cross Sectional loading:
% of Filling or Area of this segment (A1)
=
Kilns Degree
Area of cross section of Kiln (A)
Theta
Centric Angle Theta % of Kiln
(Degree) filling
110 15.65
105 13.75
100 12.1 Segment
95 10.7
r = radius inside lining
90 9.09
85 7.75 r^2
A1 = O – Sin O
80 6.52 2
75 5.42
70 4.5 A = II r^2

37. Rotary Kiln Slope versus Load
Theta 4.5 4.0 3.5 3.0 2.0
% 9 10 11 12 13
Note : In practical Kiln operation the kiln load should not exceed
13%,since higher Kiln loads impair the heat tranfer
Thumb rule by Bohman Material velocity in kiln
% Kiln Kiln diameter 1). Burning Zone = 4.5 mm / sec Lowest
Slope (m)
5 up to 2.8 m
4 3 m to 3.4 m 2). Calcining Zone = 7.5 mm / sec Max
3 > 3.4 m

38. Rotary Kiln power input calculation :
W x bd x td x N x F x 0.0000092
1
H.P =
rd
W = Total vertical load on all roller shaft bearing,lb
bd = roller shaft bearing diameter , inches Note :
This is Frictional
rd = roller diameter , inches 1
Horse Power
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

39. This is Load Horse
2
Horse Power
H.P = (D x Sin O) ^3 x N x L x K 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

40. Cement Monthly - Edelweiss
From: Arun Shourie [mailto:Arun.Shourie@edelcap.com]
Arun Shourie
Relation Manager - Insurance
Dir: +91 (22) 4086 3835 / +91 99200 29366

41. Burner pipe centering location and alignment
Burner Pipe
Location
40*
L
v
H d
D

42. =
V Z Cos O
D–a–b X K% = Z
2 H = Z Sine O
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
Kiln load = K % 5 6 7 8 9 10 11 12 13 14 15
Depth of
material bed in
Kiln = Y % 9.75 11 12.2 13.4 14.5 15.6 16.7 17.7 1.8.8 19.8 21

43. 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 B
= SCF
100 7000
Kg of Air = 10.478 SCF
Kg of Coal
a = % Moisture in coal ( as fired )
B = Heat value of coal ( Kcal / kg as fired )

44. % Loading of Kiln : Theoretical Flame
Temperature fuel oil :
Cxfxt Q
T =
L = Vg x Cp
dxV
Q = heating value of
oil , K cal / kg
C = Capacity of Kiln Ton / hr Vg = Volume of
combustion gases ,
f = Ton (Kg) dry feed / Ton ( kg) of Clinker
Nm^3 / Kg
t = residence time
Cp = Specific heat of
d = Bulk density of dry feed ton (Kg) / m^3 combustion gases
=0.40 at 2000*C for
V = Internal volume of kiln in m^3
fuel class “S”

45. Rotary kiln Capacity
Martin’s Formula :
C = 2.826 v X D^3
Vg
C = Kiln Capacity Ton / Hr
V = Gas Velocity in gas discharge end , m / sec
Vg = specific gas volume , m^3 / kg clinker
D = Kiln Diameter on Bricks, m

46. Heat capacity of Rotary kiln
1 Q = 1.1 x 10 ^ 6 x D ^3 (Kcal / hr)
D = Mean inside Kiln Diameter on Bricks, m
2 Kiln Thermal loading at cross
section of burning zone = Qp = = 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

47. 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
= Constant
ID ^ 5
V = Gas volume
ID = Inside Diameter of ducts /
cyclones respectively

48. Preheater cyclone sizing
(V) ^ 2 x Vt C
D = 0.536 4
P
Vt = V0 273 + t + K K = dust concentration in
Gas , grams / m^ 3
273
D = cyclone Diameter , m
V = Gas volume passimg cyclone , m ^ 3 / Sec
Vt = sp. gr. of gas at aver. Temp , Kg / m ^ 3
C = Coefficient for pressure drop = 110
P = Pressure drop in cyclone in mm WG

49. Small size high efficiency cyclone
L
H
70 * L=H/2
Length of Dip Tube = ½ Gas inlet height Single Stream
Pressure drop across cyclone = 55 – 60 mbar

50. Theoretical Heat consumption Q for
clinker burning :zur Strassen formula :
Constituent Constituent Multiplication Heat Cons Net
Name X % Factor Y kcal/kg
Al2O3 5.92 2.22 + 13.1 +
MgO 1.05 6.48*MgO6.48 + 6.8 527.4
CaO 63.91 7.646 + 488.7
H2O 3.2 5.86 + 18.8
_
SiO2 22.68 5.11 _ 117
118.4
Fe2O3 2.31 0.59 _ 1.4
Net % 99.27 Net Kcal / Kg = 409.0
Q = 2.22 Al203 + 6.48 MgO + 7.646 CaO + 5.86 H2O + 5.11 SiO2 + 0.59 Fe2O3

51. Thermal efficiency of cooler = E
A-B X 100
E=
A
A = Heat loss of clinker leaving the kiln
B = Heat loss of the clinker cooler
3250 (347 – K )
Secondary Air Temperature = t =
(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

52. Cooling of kiln Exit Gases (GCT)
Kg / min.Exit gas x 0.25 ( t 1 – t 2) Kcal / min
Y=
H t2 – H t3
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