strict process audit in cement industry.pptx

1. Cement Manufacturing Process

2. U N I T - I U N I T - II
B L E N D E D L / S B L E N D E D L / S
R A W M E A L
K I L N F E E D F I N E C O A L F I N E C O A L K I L N F E E D
C R U S H I N G A N D S T A C K I N G P R O C E S S
C R U S H E D L I M E S T O N E
S T O C K P I L E
R A W M E A L G R I N D I N G
P R O C E S S
R A W M E A L
M A N U F A C T U R I N G
L / S F R O M M I N E S
C B S I L O R A W M E A L
S T O R A G E & H O M O G .
L A T E R I T E
C F S I L O R A W M E A L
S T O R A G E & H O M O G .
C E M E N T P R O C E S S
R E C L A I M I N G P R O C E S S R E C L A I M I N G P R O C E S S
C L I N K E R S T O C K P I L E
P Y R O P R O C E S S
H O T C L I N K E R
P Y R O P R O C E S S
H O T C L I N K E R
C L I N K E R C O O L E R
C O L D C L I N K E R
C L I N K E R C O O L E R
C O L D C L I N K E R
C R U S H E D C O A L
C L I N K E R S T O C K P I L E
R A W M E A L G R I N D I N G
P R O C E S S
C O A L C R U S H I N G
S T A C K I N G & R E C L A I M I N G
C O A L G R I N D I N G
P R O C E S S
U N I T-I U N I T-II

3. CRUSHER
Crushing
 Input Size: 1-2m
 Product Size
 25 mm for Ball mills
 50 - 75 mm for VRM
 (Based on mill size)

4. Pre-Homogenizing of Materials
© Confederation of Indian Industry
 Objective:
 Homogenizing of Raw Materials
 Raw Material Storage
 Raw Material Stacking
 Raw Material Reclaiming

5. Stacker / Reclaimer
© Confederation of Indian Industry

6. Raw Material Grinding
Input Size 50-75
mm
VRM
Product size 15%
on 90 micron

7. Raw Mill-Operating Principle
45 – 60 m/s
1500 – 3000
%
Nozzle Ring
Recirculation 10-25%
100 %
10 – 25%
New Feed 100%

8. Process Flow Sheet Raw Mill

9. Quality Parameters for Raw Mix Design
 Silica Modulus
 Increase in Silica ratio – Difficult to burn.
 Hard to burn
 Lower sintering temperature
Al2 O3  Fe2 O3
SiO6
S / R 

10. Quality Parameters for Raw Mix Design
 Alumina Modulus:-
F e 2 O 3
 Ratio indicates the quantity of initial liquid
phase present during burning
A /F 
A l 2 O 3

11. Quality Parameters for Raw Mix Design
 LSF-Lime Statutaration Factor
A /F  0 . 6 4
2 . 8 S i O 2  0 . 7 F e 2 O 3
 1 . 1 A l 2 O 3
2 . 8 S i O 2  0 . 3 5 F e 2 O 3
 1 .6 A l 2 O 3
A /F  0 . 6 4
C a O
L S F 
C a O
L S F 

12. Lime Saturation Factor
 Lime-Saturation Factor = 1:- The clinker is difficult to
burn.
 High free lime content.
 Over limed – LSF = 0.97.
 Excellent indicator.
 Permissible range of variation of free-lime contents –
0.4 and 1.2%.

13. Raw Mix Design
 Depending Factors
 Type of Coal(Pet coke or coal)
 Lime Stone Quality
 Sulphur alkali ratio in Case of petcoke

14. Pyro process Optimization
 Inputs:-
 Kiln Feed
 Primary Air
 Cooling Air
 Coal
Outputs
Clinker
PH exit Gases
Cooler vent
Return dust

15. ILC –Double String Kiln System

16. ILC –Kiln System

17. SLC - Kiln System

18. Primary Air
 Just enough to carry and mix with the fuel
thoroughly
 May vary from 5 to 15 % of total air fed to kiln
system but should be as little as possible
 Burner nozzle velocity : 80-120 m/sec
 Primary air to fuel ratio : 0.8-1.3

19. Effects of Primary Air on Combustion
Increase in primary air causes :
 Decrease in flame temperature
 Decrease in thermal efficiency of kiln and cooler
 Increase in fuel consumption
Decrease in primary air leads to :
 Choking in primary air conveying pipe
 Improper mixing/turbulence

20. Secondary Air
 It is the main part of the combustion air (85 – 95% of total
air fed)
 Preheating of air is done in contact with hot outgoing clinker
in the cooler
 Temperature
700-8500c for wet process
900-10500c for dry process
 Velocity of the secondary air : 9-11 m/sec
 Flame direction is usually affected by the buoyancy of
secondary air

21. Effects of Increasing Secondary Air on Combustion
 Increases thermal efficiency of kiln and cooler
 Increases flame temperature
 Increases coal consumption
 Affects flame direction

22. Chemical Reactions Inside kiln & Preheater
Temp
(Deg C )
Process Chemical
Transformation
< 100 Drying, removal of H2O (l)  H 2O (g)
Al 2(OH)8Si 4O10
 2(Al2O3. 2SiO2)
+4H 2O
Al 2O3. 2SiO2 Al 2O3. +
+2SiO2
water
Decomposition of
100-400 clay with formation
of kaolinite
Decomposition of
600-900 metakaolinite to a
mixture of free
reactive oxides

23. 600- 1000 CaCO 3  CaO +CO 2
3CaO+ 2SiO 2+2Al 2O3
 2( CaO.SiO z) +
CaO.Al 2O3
Decomposition of
limestone and
formation of CS
and CA
Decomposition of
limestone and
800-1300
formation of C2S,C
3Aand C4AF
2CaO +SiO
 2CaO.SiO
2
2
CaO.Al 2O3+2CaO
 3CaO.Al 2O3
CaO.Al 2O3+3CaO
+Fe 2O3 
4CaO.Al 2O3.Fe zO3
2CaO 2.SiO 2 CaO 
1250-
1450
Further binding of
lime by C2S to form
C3S
3CaO.SiO 2
Chemical Reactions Inside kiln & Preheater

24. Chemical Reactions Inside kiln & Preheater
MgCO3
Organic Carbon
Sulfur as pyrites
: MgCO3 - > MgO +CO2
: C + O2 -> CO2
: 2 FeS2 + 6 1/2 O2 +
2 CaCo3 -> Fe2O3 +
2 SO2+2CaSO4 +2 CO2
Sulfur in fuel : 2S + 3 O2 -> 2SO3
CaO + SO3 -> CaSO4
: CO2 + CaO - > CaCO3 + heat
Recarbonation

25. Heat And Mass Balance Inputs
Primary
air
Kiln feed
Cooling air False air

26. Heat and Mass Balance Outputs
Clinker
Cooler waste / middle
air
Radiation
and
Convection
PH
exhaust
gas/dust

27. Heat Input
INPUT
Mass flow Specific heat Temperature Heat Input
kg/kg
clinker
Kcal/Kg0
C 0C
Kcal/Kgclinker
Sensible heat of kiln feed 1.60 0.213 75 25.60
Sensible heat of kiln feed
moisture 0.02 0.446 75 0.803
Sensible heat of Fine Coal 0.09 0.289 70 1.87
Sensible heat of Primary air 0.08 0.238 32 0.58
sensible heat of cooling air 2.57 0.238 32 19.58
Sensible heat of conveying air 0.06 0.238 32 0.49
NCV of fuel
heat of fuel 738.34
sensible heat of fine coal
moisture 0.002 0.446 68 0.056
4.36
Total Heat Input 48.98

28. Heat Output
OUTPUT
Mass flow Specific heat Temperature Heat Output
kg/kg clinker Kcal/Kg0
C 0
C
Kcal/Kg
clinker
Sensible heat preheater exit gases
string
2.277 0.26 296 178.02
Sensible heat of raw meal return dust 0.1 0.24 296 6.87
Sensible heat of cooler exit gases 1.67 0.24 281 113.36
Heat of Formation of clinker 400
Cooler & Kiln Hood Radiation 2.99
Kiln Radiation 26.79
T.A.D. radiation 1.3735
Preheater Radiation 41.91
Sensible Heat of clinker 1 0.19 85 16.28
TOTAL HEAT OUTPUT 5.04 787.33
overall radiation loss (kcal/kg
clinker)
73.07
%overall heat loss in radiation 9.28

29. Optimum Parameters
 Cooling air for new generation: 2.2 kg air/kg clinker
 Preheater Gas Volume: 1.5 Nm3/kg Clinker (Pet- coke) &
1.3-1.5 Nm3/kg Clinker(Coal).
 Cooler Vent air: 1.0 Nm3/Kg Clinker.
 Overall radiation loss: 7-8%
 False air: 8% across preheater
 Preheater Outlet Temp: 250 degree C for 6 Stage.
 Pressure drop: 450-500 mmwg for 6 stage.

30. Cooling Air Requirement per kg Clinker
300
275
250
225
200
175
150
125
100
75
50
1.4 1.9 2.4
Specific Cooling Air [Nm3/kg Clinker]
Clinker
End
T
[°C
above
Ambient]

31. Cooling Air requirement for different
Generation Coolers

32. Effect of grate resistance on air distribution
Cooler Bed Height Depends on Material
characteristics

33. Effect of resistance grates
TRADITIONAL COOLER
KILN
UNEVEN AIR
FLOW
PROFILE
FINE SIDE
cooling
air fan
cooling air
cooling air
cooling air
sealing air
EVEN AIR
FLOW
PROFILE
COOLAX-CFG COOLER
KILN

34. Cooler Efficiency

35. Simplified Cooler Balance Conventional
TOTAL COOLER LOSS: 160 kcal/kg
STD. COOLER LO
:SS: 130 kcal/kg

36. Simplified Cooler Balance Modern Cooler
TOTAL COOLER LOSS: 105 kcal/kg
STD. COOLER LOSS: 85 kcal/kg

37. Optimized Cooler Loss
A . P L A N E T A R Y C O O L E R
R a d i a t i o n 9 7
C l i n k e r ( 1 5 0 º C ) 2 5
1 2 2 k c a l / k g
B . R O T A R Y C O O L E R
R a d i a t i o n 7 5
C l i n k e r ( 2 2 5 º C ) 4 5
1 2 0 k c a l / k g
C . C O N V E N T I O N A L G R A T E C O O L E R
R a d i a t i o n 6
E x c e s s A i r ( 1 . 8 5 k g / k g @ 2 4 0 º C ) 1 0 8
C l i n k e r ( 9 0 º C ) 1 7
1 3 1 k c a l / k g
D. A I R - B E A M G R A T E C O O L E R
R a d i a t i o n 6
E x c e s s A i r ( 1 . 2 k g / k g @ 2 4 0 º C ) 7 0
C l i n k e r ( 9 0 º C ) 1 7
9 3 k c a l / k g
E . C R O S S - B A R C O O L E R
R a d i a t i o n 6
E x c e s s A i r ( 1 . 0 k g / k g @ 2 4 0 C ) 5 8
C l i n k e r ( 9 0 C ) 1 7
8 1 k c a l / k g

38. Mill Optimization
© Confederation of Indian Industry

39. VERTICAL ROLLER MILL
Feed
chute
Separator
Housing
Roller
Grinding table
Adjustable nozzle
ring
Gear box

40. Optimization of VRM
 Optimization of feed size
 Optimization of Dam Ring height & Nozzle Ring velocity
 Optimization of air quantities & Temp in Mill circuit
 Minimization of false air in the circuit
 Optimization of product residue
 Operation of Mill with high level control system

41. Nozzle Ring Velocity
 Minimum velocity is required to lift material.
 Raw mill-35-50 m/sec
 Coal mill petcoke-45-60 m/sec
 Coal mill-40-60 m/sec

42. Optimum Air Velocity at Nozzle Ring in m/sec
With recirculation system : 40 to 45 m/sec
Without recirculation system : 60 to 65 m/sec

43. Dam Ring Height
 Generally-2-4% of Table Dia
 Observations:-
 Dam ring height too high
 High mill motor current
 Low Mill DP
© Confederation of Indian Industry

44. Dam Ring Height
 Generally-2-4% of Table Dia
 Observations:-
 Dam ring height too LOW
 Low mill motor current
 Low Mill DP
 High rejects level
 Low mill output
 High Vibration than Normal
© Confederation of Indian Industry

45. Mill Grinding Pressure
 Operating Pressure as per
supplier.
 Observations:-
 Low grinding pressure
 Low mill motor current
 Low capacity for given air flow and DP.
 High rejects level
 High DP across nozzle ring and separator.

46. Nozzle Modification

47. Electrical Energy Consumption Per Section

48. Latest Inhouse Modifications In Cement
plants
 Suction Box Modifications of Process
fans
 Pressure drop stick inside the cyclones.
 Installation of Baffle plate in Cooler.
 Nozzle ring design in Mills.

49. Suction Box Modification in Raw MILLS
Raw Mill 2fan 1 UOM Before After
Flow m3/
hr.
789550 779600
Pressure at fan
I/L
mmw
g
-940 -910
Fan speed rpm 965 935-950
Fan Kwh kWh 3200-
3250
3150-
3200
Raw Mill 1fan1 UOM Before After
Flow m3/h
r.
810000 800000
Pressure at fan
I/L
mmw
g
-1100 -1040
Fan speed rpm 965 950
Fan Kwh kWh 3000 2850
1. Raw mill1 Fan inlet suction box
increased by extending the
width by 330mm.
2. Raw mill 2 fan inlet suction box
increased by extending the
width by 385mm.

50. Modification in Pyrosection
 TAD Ramp has been made to increase the
oxygen percentage at kiln inlet.
 Around 35% blocked the area.
 Shifting of cooler water spray nozzles from
take off duct to centre of cooler wall.

51. Modification in coal mill for pet coke
grinding
Parameters Before
modification
After modification
Dam Ring height(mm) 145 120
Nozzle ring
velocity(m/s)
41 60
Static vanes gap(mm) 35-40mm 30mm
Mill outlet dust
load(gm/m3)
170 210
Residue(90 micron) in
pet coke.
8% 1.2% - 3%

52. Installation of Baffle Plate at null point in
cooler
Before After
Input Cooling air(kg
air/kg clinker)
2.6 2.36
Specific power of
cooler ID fan(kwh/t
clinker)
0.714 0.542
Cooler Vent
Volume(Nm3/hr)
276834 234164
Specific heat
consumption(Kcal/kg
clinker)
690 685