formulas kiln
DESCRIPTION
This contains critical practical formulas for Kiln Performance in comparision toTRANSCRIPT
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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
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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
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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
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100* CaO
LSF =
(2.8 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3)
0.66 > LSF < 1.2
= =
LIME SATURATION FACTOR
AR = > 0.64
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SiO2
SR =
(Al2O3 + Fe2O3)
2.2 > SR < 2.6
= =
SILICA RATIO
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Al2O3
AR =
Fe2O3
1.5 > AR < 2.5
= =
ALUMINA RATIO
AR < 1.5 IS CALLED FERROCEMENTS
AR = 0.637 IS CALLED FERRARI CEMENT
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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
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COAL USED IN CEMENT INDUSTRY
• LHV = 6500 – 7000 Kcal / Kg
• ASH = 12~15 %
• VOLATILE MATERIAL = 18~ 22 %
• MOISTURE = UP TO 12 %
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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
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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
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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
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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.
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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)
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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
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CEMENT MILL FORMULAS
MILL CRITICAL VELOCITY = 76 / (D)^1/2
MILL ACTUAL VELOCITY = 32 / (D)^1/2
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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’
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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
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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.
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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
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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
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70 *
H
L
L=H/2
Length of Dip Tube = ½ Gas inlet height Single Stream
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ESP ELECTROSTATIC PRECIPITATOR
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GASCONDITIONING TOWER SPRAY
TOP VIEW
SIDE VIEW
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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
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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)
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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
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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
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MID KILN
FEEDING
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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
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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
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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 :
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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+
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Arun Shourie
Relation Manager - Insurance
Dir: +91 (22) 4086 3835 / +91 99200 29366
Cement Monthly - Edelweiss
From: Arun Shourie [mailto:[email protected]]
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D
d
L
v
H
Burner Pipe
Location40*
Burner pipe centering location and alignment
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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 %
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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
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% 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”
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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
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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
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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
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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
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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
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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
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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
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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
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