Kiln Systems
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Kiln Systems
Dick Bekker CTL/TT
The Rotary Kiln
2
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
In the Kiln System….. ..the following processes occur:
1. Drying 2. Preheating 3. Calcination 4. Sintering 5. Cooling 3
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Materials into the kiln – Raw Feed The Primary Feed materials to the Kiln system are:
Limestone Silica Aluminum Iron
These supply
CaO SiO2 Al2O3 Fe2O3
(C) (S) (A) (F)
These raw materials must be present in the correct
proportions in the ‘raw meal’ or kiln feed. 4
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Major Clinker Compounds The kiln system produces the clinker compounds from raw-meal and coal ash C3S
3CaO•SiO2
alite
C2S
2CaO• SiO2
belite
C3A
3CaO• Al2O3
aluminate
C4AF
4CaO• Al2O3• Fe2O3
ferrite 5
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Significance of the Clinker Minerals.. C3S C2S
Contributes to early strength (1 - 28d+) Contributes to late strength (28 d - ...) Increases heat of hydration Contributes to very early strength (1 - 2 d)
C3A
Increases heat of hydration Reduces resistance to sulphate attack
C4AF Little effect 6
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Clinker Production Processess
We can identify four distinctly different production processes
1. Wet Process 2. Dry Process 3. Semi-dry Process 4. Semi-wet Process
The wet process was the predominant process in the past.
Today all new installations are dry process based 7
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Wet Production Process
8
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Wet Kiln System
9
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Semi-Wet Production Process
10
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Semi-Wet Kiln System - with grate preheater “LEPOL”
11
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Semi-Dry Kiln System - with grate pre-heater “LEPOL”
12
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Production Process
13
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Process Kiln System– Pre-Heater
14
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Process Kiln System -
Pre-Heater and Pre-Calciner
15
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Process Kiln - Pre-Heater and Pre-Calciner Five processes occur in a kiln • Drying • Preheating • Calcining • Sintering • Cooling
Preheater Pre-calciner Kiln
Holcim Group Support
60% Fuel Split 40%
Introduction to Cement Concrete & Aggregates
16
August 2006
Components of a Kiln System
17
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Components of a Kiln System
18
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Components of a Kiln System
Chains
19
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Co-Current Heat Exchange
20
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Double Pendulum Flap
21
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
5-Stage Cyclone Preheater
22
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Components of a Kiln System
23
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Counter-Current Heat Exchange
24
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Pre Calciner - General Features Gases To Second Stage
Raw Meal IN
Fuel Raw Meal To Kiln Gases from Kiln Holcim Group Support
Introduction to Cement Concrete & Aggregates
25
August 2006
Components of a Kiln System
26
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Kiln at Devil’s Slide
27
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Kiln Tire and Shell
28
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Kiln Shell Support & Drive - Dry Process
29
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
The Kiln Hood
30
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
The Kiln Hood Connects the kiln to the cooler Access door for maintenance and associated
equipment Orifice for the burner Cooled sight holes for observation, pyrometer, etc
31
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Components of a Kiln System
32
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
The Burner Pipe
33
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
The Ideal Flame
hot ! short ! stable ! Complete combustion: - CO = 0 - SO2, NOx
"long" flame
T
"short" flame
Homogeneous: - no temperature peaks - no local CO on the clinker bed 34
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Coal and Gas Burner
35
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Burners
36
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Burner Adjustment Adjustment of tip cross section axial- and radial air channel
connection central air transport air
Coal
Oil PA
Kiln
central air damper / flap
axial- and radial air damper / flap
Typical burner set-up (Rotaflam): 60% axial air, 30% radial air, central air 50mbar ( 10%) 37
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Coal and Oil burner before Operation
38
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Coal and Oil burner after Operation
39
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Alternative Fuels
Recycling wastes as fuel not only saves energy but also
safely destroys them
40
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Wet v/s Dry - A Question of Cost
Chains
41
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Wet v/s Dry - A Question of Cost WET Process
DRY Process
kJ / kg Clinker
%
kJ / kg Clinker
%
Evaporation of water
2050
38
20
1
Heat of reaction
1760
33
1760
55
Heat loss from Process
1050
19
1120
35
540 Radiation & Convection TOTAL 5,400
10
300
9
100%
3,200
100% 42
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Energy Consumption by Process Type
PH/PC Short Dry/PH Long Wet
KJ/kg 7000 6500 6000 5500 5000 4500 4000 3500 3000 2500
250
500
1000
1500
2000
2500
3000
3500
4000
6000 10000
Tons/Day
Source: Holnam 44
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Process Kiln - Pre-Heater and Pre-Calciner • Highest efficiencies – as low as 2,900 kJ/Kg • High capacity - up to 4,000 T/d for each pre-calciner string • Up to 12,000T/d per kiln system • Very low quantity of solid waste • System of choice for ‘modern” plants
Preheater Precalciner Kiln
Holcim Group Support
Introduction to Cement Concrete & Aggregates
45
August 2006
Main Equipment of a Modern Kiln System
Dry process kiln (with 5-stage SP and PC Dry process kiln (with 5-stage SP and PC) Kiln ID Kiln ID Fan
Fan Filter Fan
Cooler Dedusting
Meal Dosing
Meal Dosing
Precalciner Fuel Dosing Air-to-Air
5-stage 5-stage Suspension Suspension Preheater
Precalciner Fuel Dosing
Preheater
Cooler
Water
Kiln Fuel Dosing
Low NOx Precalciner Low NOx Burner
Precalciner
Primary Burner Air Fan Cyclone Preheater
Cyclone Preheater
Holcim Group Support Introduction to CementKiln Concrete & Aggregates Drive Burning Zone
Conditioning Tower
46
August 2006
The Optimum Kiln System 2005 1) 5 stage preheater with low pressure drop cyclones 2) Large in-line calciner with AFR feeder
5) Oversized kiln for AFR 6) High momentum multi channel burner
3) Low NOx with staged TA swirl chamber
4) Pre-combustion chamber, staged meal feed
7) High efficiency cooler 8) Roller crusher 10) Splined tyre fixation
9) Pneumatic seals on both ends 47
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Starting up the Kiln System
Dry process kiln (with 5-stage SP and PC Dry process kiln (with 5-stage SP and PC) Kiln ID Kiln ID Fan
Fan Filter Fan
Cooler Dedusting
Meal Dosing
Meal Dosing
Precalciner Fuel Dosing Air-to-Air
5-stage 5-stage Suspension Suspension Preheater
Precalciner Fuel Dosing
Preheater
Cooler
Water
Kiln Fuel Dosing
Low NOx Precalciner Low NOx Burner
Precalciner
Primary Burner Air Fan Cyclone Preheater
Cyclone Preheater
Holcim Group Support Introduction to CementKiln Concrete & Aggregates Drive Burning Zone
Conditioning Tower
48
August 2006
Dick Bekker CTL/TT
The Rotary Kiln
2
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
In the Kiln System….. ..the following processes occur:
1. Drying 2. Preheating 3. Calcination 4. Sintering 5. Cooling 3
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Materials into the kiln – Raw Feed The Primary Feed materials to the Kiln system are:
Limestone Silica Aluminum Iron
These supply
CaO SiO2 Al2O3 Fe2O3
(C) (S) (A) (F)
These raw materials must be present in the correct
proportions in the ‘raw meal’ or kiln feed. 4
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Major Clinker Compounds The kiln system produces the clinker compounds from raw-meal and coal ash C3S
3CaO•SiO2
alite
C2S
2CaO• SiO2
belite
C3A
3CaO• Al2O3
aluminate
C4AF
4CaO• Al2O3• Fe2O3
ferrite 5
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Significance of the Clinker Minerals.. C3S C2S
Contributes to early strength (1 - 28d+) Contributes to late strength (28 d - ...) Increases heat of hydration Contributes to very early strength (1 - 2 d)
C3A
Increases heat of hydration Reduces resistance to sulphate attack
C4AF Little effect 6
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Clinker Production Processess
We can identify four distinctly different production processes
1. Wet Process 2. Dry Process 3. Semi-dry Process 4. Semi-wet Process
The wet process was the predominant process in the past.
Today all new installations are dry process based 7
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Wet Production Process
8
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Wet Kiln System
9
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Semi-Wet Production Process
10
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Semi-Wet Kiln System - with grate preheater “LEPOL”
11
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Semi-Dry Kiln System - with grate pre-heater “LEPOL”
12
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Production Process
13
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Process Kiln System– Pre-Heater
14
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Process Kiln System -
Pre-Heater and Pre-Calciner
15
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Process Kiln - Pre-Heater and Pre-Calciner Five processes occur in a kiln • Drying • Preheating • Calcining • Sintering • Cooling
Preheater Pre-calciner Kiln
Holcim Group Support
60% Fuel Split 40%
Introduction to Cement Concrete & Aggregates
16
August 2006
Components of a Kiln System
17
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Components of a Kiln System
18
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Components of a Kiln System
Chains
19
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Co-Current Heat Exchange
20
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Double Pendulum Flap
21
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
5-Stage Cyclone Preheater
22
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Components of a Kiln System
23
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Counter-Current Heat Exchange
24
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Pre Calciner - General Features Gases To Second Stage
Raw Meal IN
Fuel Raw Meal To Kiln Gases from Kiln Holcim Group Support
Introduction to Cement Concrete & Aggregates
25
August 2006
Components of a Kiln System
26
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Kiln at Devil’s Slide
27
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Kiln Tire and Shell
28
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Kiln Shell Support & Drive - Dry Process
29
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
The Kiln Hood
30
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
The Kiln Hood Connects the kiln to the cooler Access door for maintenance and associated
equipment Orifice for the burner Cooled sight holes for observation, pyrometer, etc
31
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Components of a Kiln System
32
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
The Burner Pipe
33
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
The Ideal Flame
hot ! short ! stable ! Complete combustion: - CO = 0 - SO2, NOx
"long" flame
T
"short" flame
Homogeneous: - no temperature peaks - no local CO on the clinker bed 34
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Coal and Gas Burner
35
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Burners
36
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Burner Adjustment Adjustment of tip cross section axial- and radial air channel
connection central air transport air
Coal
Oil PA
Kiln
central air damper / flap
axial- and radial air damper / flap
Typical burner set-up (Rotaflam): 60% axial air, 30% radial air, central air 50mbar ( 10%) 37
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Coal and Oil burner before Operation
38
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Coal and Oil burner after Operation
39
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Alternative Fuels
Recycling wastes as fuel not only saves energy but also
safely destroys them
40
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Wet v/s Dry - A Question of Cost
Chains
41
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Wet v/s Dry - A Question of Cost WET Process
DRY Process
kJ / kg Clinker
%
kJ / kg Clinker
%
Evaporation of water
2050
38
20
1
Heat of reaction
1760
33
1760
55
Heat loss from Process
1050
19
1120
35
540 Radiation & Convection TOTAL 5,400
10
300
9
100%
3,200
100% 42
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Energy Consumption by Process Type
PH/PC Short Dry/PH Long Wet
KJ/kg 7000 6500 6000 5500 5000 4500 4000 3500 3000 2500
250
500
1000
1500
2000
2500
3000
3500
4000
6000 10000
Tons/Day
Source: Holnam 44
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Dry Process Kiln - Pre-Heater and Pre-Calciner • Highest efficiencies – as low as 2,900 kJ/Kg • High capacity - up to 4,000 T/d for each pre-calciner string • Up to 12,000T/d per kiln system • Very low quantity of solid waste • System of choice for ‘modern” plants
Preheater Precalciner Kiln
Holcim Group Support
Introduction to Cement Concrete & Aggregates
45
August 2006
Main Equipment of a Modern Kiln System
Dry process kiln (with 5-stage SP and PC Dry process kiln (with 5-stage SP and PC) Kiln ID Kiln ID Fan
Fan Filter Fan
Cooler Dedusting
Meal Dosing
Meal Dosing
Precalciner Fuel Dosing Air-to-Air
5-stage 5-stage Suspension Suspension Preheater
Precalciner Fuel Dosing
Preheater
Cooler
Water
Kiln Fuel Dosing
Low NOx Precalciner Low NOx Burner
Precalciner
Primary Burner Air Fan Cyclone Preheater
Cyclone Preheater
Holcim Group Support Introduction to CementKiln Concrete & Aggregates Drive Burning Zone
Conditioning Tower
46
August 2006
The Optimum Kiln System 2005 1) 5 stage preheater with low pressure drop cyclones 2) Large in-line calciner with AFR feeder
5) Oversized kiln for AFR 6) High momentum multi channel burner
3) Low NOx with staged TA swirl chamber
4) Pre-combustion chamber, staged meal feed
7) High efficiency cooler 8) Roller crusher 10) Splined tyre fixation
9) Pneumatic seals on both ends 47
Holcim Group Support
Introduction to Cement Concrete & Aggregates
August 2006
Starting up the Kiln System
Dry process kiln (with 5-stage SP and PC Dry process kiln (with 5-stage SP and PC) Kiln ID Kiln ID Fan
Fan Filter Fan
Cooler Dedusting
Meal Dosing
Meal Dosing
Precalciner Fuel Dosing Air-to-Air
5-stage 5-stage Suspension Suspension Preheater
Precalciner Fuel Dosing
Preheater
Cooler
Water
Kiln Fuel Dosing
Low NOx Precalciner Low NOx Burner
Precalciner
Primary Burner Air Fan Cyclone Preheater
Cyclone Preheater
Holcim Group Support Introduction to CementKiln Concrete & Aggregates Drive Burning Zone
Conditioning Tower
48
August 2006
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