Residence time in Kiln “t” =
Phy
L
1.77 (Phy)^1/2 L ________________ Alpha* D*N
=Angle of repose for lime stone ~ 36 Degree = length of Kiln in meter
Alpha = Kiln inclination in % D
= Effective diameter of Kiln in meter
N
= Rotation per minute rpm
Kiln
Kiln
Inlet
Outlet
A
B
C
Preheater Zone = 1 min
D
E
A
7.5m/sec Mat velo Max
Precalcination Zone = 2 min
B =
Calcination Zone = 10-12 min
C
Burning Zone = 6 – 8 min
D
Cooling Zone = 2 min
F
t = 20 -28 Minutes
4.5m/sec Mat Velo Min
CLINKERISATION 12 CaO Lime stone
3Cao.SiO2 (C3S) Alite
2 SiO2 Silica oxide
2CaO SiO2 (C2S) Belite
1450*C 2 Al2O3 Aluminium oxide
Fe2O3 Iron oxide
3 CaOAl2O3 (C3A) Tricalcium Aluminate
4CaO.Al2O3.Fe2O3 (C4AF) Tetra Calcium Alumino Ferrite
LIME SATURATION FACTOR
100* CaO LSF = (2.8 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3) 0.66 > LSF < 1.2 = = AR = > 0.64
SILICA RATIO
SiO2 SR = (Al2O3 + Fe2O3) 2.2 > =
SR < 2.6 =
ALUMINA RATIO
Al2O3 AR = Fe2O3 1.5 > =
AR < 2.5 =
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
LHV = LOW HEATING VALUE Kcal /Kg HHV = HIGH HEATING VALUE Kcal /Kg M = % MOISTURE
H = % HYDROGEN
KCal / Kg x 4.187 x 10^(-3) = MJ/Kg KCal / Kg x 1.8 = Btu / lb
O = % OXYGEN
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
TxL
Skin Temperature Diagram
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 A1= (T2a+T1)/2 - T A1= (T2b+T1)/2 - T Ambient temp = T
X L1 X L2
T2bb T1 T2a
A = A1 +A2
L2
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
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)
PH fan-1 Twin cyclones IA
PH fan-2 Twin cyclones
IB
II III IV
Riser Duct KILN STRING
V VI V
950*C T.A.Duct SLC
PYRO STRING
KILN I Girth gear
II
III
CEMENT MILL FORMULAS
MILL CRITICAL VELOCITY = 76 / (D)^1/2
MILL ACTUAL VELOCITY = 32 / (D)^1/2
D
Mill charging:
Theta’ 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 )’
GRINDING MEDIA LOAD “ G”
G = gm.Sy.Pi. (R)^2.L 4
G = 4620(R)^2.L TAGGARTS FORMULA
Constants:
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
POWER CONSUMPTION OF MILL = P L= G/D=A-C
2.
B-A
P= 12G
SEPARATOR B%fines/D A %fines/F
Seperator efficiency s
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
C%fine/G
Ball Mill
1. n = C (A-B) A(C-B))
3. F = L(1+D)
L/D=3 L / D = 4.5
Two Compartment Mill Three Compartment Mill
I – Chamber Drag Peb Liners
Carman Lining
Classifying Liners
Slegton – Magotteaux Lining Lining
FLS Lining
Important Conversions
1 Barrel = 42 Gallons = 159 litres = 5.615 Cuft 1 Kcal = 4.187 J
Characteristic Blaine 3 Days(MPa) 7 Days 28 Days
KCal / Kg x 1.8 = Btu / lb
OPC-43(IS8112)
225 23 33 43
OPC-43(IS12269)
225 27 37 53
PPC- (IS1489)Part-1
300 16 22 33
L
H 70 *
L=H/2
Length of Dip Tube = ½ Gas inlet height
Single Stream
ESP ELECTROSTATIC PRECIPITATOR
TOP VIEW
GASCONDITIONING TOWER SPRAY
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
Desc
Kiln string
Pyro string
I Cyclone Twin (Diameter)
4000 m 6400 m
4400 m 7000 m
Dip tube (Diameter)
2000 m 3200 m
2200 m 3500 m
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 :
Main Drive
Material of construction = CS 640 (Normalized Cast Steel) Dimensions = 5620 OD x 4581 ID x 775 (width) Tyre Supporting Roller Girth Gear
Pinion
Kiln Shell
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 RWB-178
G.B G.B
Motor
Pinion
Kiln Axis Concord Alingnomatic Geared Coupling
G.G
MID KILN FEEDING
Degree Of Kiln filling & Kiln Cross Sectional loading:
Area of this segment (A1)
% of Filling or Kilns Degree
= Area of cross section of Kiln (A)
Centric Angle Theta (Degree)
% of Kiln filling
110
15.65
105
13.75
100
12.1
95
10.7
90
9.09
85
7.75
80
6.52
75
5.42
70
4.5
Theta
Segment r = radius inside lining
A1 =
r^2
O – Sin O
2
A = II r^2
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 % Kiln Slope
Kiln diameter (m)
5
up to 2.8 m
4
3 m to 3.4 m
3
> 3.4 m
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 :
H.P =
W x bd x td x N x F x 0.0000092
1
rd
W = Total vertical load on all roller shaft bearing,lb bd = roller shaft bearing diameter , inches rd = roller diameter , inches
Note : This is Frictional 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
1
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
Cement Monthly - Edelweiss From: Arun Shourie [mailto:
[email protected]]
Arun Shourie Relation Manager - Insurance Dir: +91 (22) 4086 3835 / +91 99200 29366
Burner pipe centering location and alignment Burner Pipe Location
40* L v H
D
d
D–a–b
X
=
K%
Z
=
V
Z Cos O
H = Z Sine O
2 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
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 Kg of Air
B 7000
=
=
SCF
10.478 SCF
Kg of Coal a = % Moisture in coal ( as fired ) B = Heat value of coal ( Kcal / kg as fired )
% Loading of Kiln :
L
=
Cxfxt dxV
Theoretical Flame Temperature fuel oil : T =
Q Vg x Cp
Q = heating value of oil , K cal / kg 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
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 : v 2.826 C = 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
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
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
D = 0.536
(V) ^ 2 x Vt 4
Vt = V0 273 + t + K 273
C P
K = dust concentration in Gas , grams / m^ 3
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
Small size high efficiency cyclone
L
H 70 *
L=H/2
Length of Dip Tube = ½ Gas inlet height Pressure drop across cyclone = 55 – 60 mbar
Single Stream
Theoretical Heat consumption Q for clinker burning :zur Strassen formula : Constituent Constituent Name
X
%
Multiplication Factor Y
Al2O3
5.92
MgO
1.05 6.48*MgO6.48 63.91 7.646
CaO
2.22
Heat Cons Net kcal/kg
+ 13.1 + 6.8 + 488.7 + 18.8
H2O
3.2
5.86
SiO2
22.68
5.11
Fe2O3
2.31
0.59
_ 117 _ 1.4
Net %
99.27
Net Kcal / Kg
= 409.0
+ 527.4
_ 118.4
Q = 2.22 Al203 + 6.48 MgO + 7.646 CaO + 5.86 H2O + 5.11 SiO2 + 0.59 Fe2O3
Thermal efficiency of cooler = E E=
A-B
X 100
A A = Heat loss of clinker leaving the kiln B = Heat loss of the clinker cooler
Secondary Air Temperature = t =
3250 (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)
Y=
Kg / min.Exit gas x 0.25 ( t 1 – t 2) Kcal / min
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
