04_combustion And 10 Golden Rules.pptx

COMBUSTION AND TEN GOLDEN RULES Murat SOYLU October 2012

RULE 1 • Obtaining finer material on 90 and 200 µ residues decreases the burning heat and cement grinding specific energy. • This also makes the strength higher. • Decrease the residue amount from 20% to 10% on 100 µ mesh, gain 4 kWh/t energy.

By Producing Finer Meal • Saving for: – Burning fuel energy, – Cement grinding energy Is obtained…

Finer Meal = kW

25

kWh/t

y = - 0.4267 x + 29.759

y = -0.4267x + 29.759 2

24

R = 0.9145

23

22

21

(%) > 100 µm of raw mix

20 12

14

16

18

20

22

Finer Meal = Energy Saving %Free lime 8.00

15%>100 Microns- Industrial as it is 6.00

5%>100 5%>100

- lab grinding of residue - complete grinding

4.00

2.00

0.00 1400

1450

1500

1550

Temperature °C 1600

Finer Meal = Saving on Grinding Energy

Rule 2 • Short burning zone effects the grindability and strength development positively.

Hot and Short Burning Zone • Makes the clinker easily grindable.

Short Burning Zone = Better Grindability 75

BB10 (kWh/t)

70 65 60 55 50

Nm

45 600

700

800

900

1000

Kiln Motor

1100

1200

1300

1400

1500

Short Burning Zone = Better Grindability

(Grindability

500

80

450

75

Increasing grindability

400

70

350

65

300

60

250

55

Decreasing kiln motor current

200 30/05/1995 04:00

50 30/05/1995 12:00

30/05/1995 20:00

31/05/1995 04:00

31/05/1995 12:00

kWh / t

Kiln motor current, A

and Burning Zone Length)

Rule 3

• Stable conditions requires oxidizing environment. • Reducing environment increases the volatile cycle. • This causes the fluctuations of alkali sulphate and circulating elements. • Thus, bad clinker is produced.

Let the Kiln Breathe • With the reduction of volatile matter; – Stable kiln operation, – Stable clinker quality Are achieved.

Rule 4 • Increase of clinker free lime content decreases the initial and final setting time. • Limestone addition accelerates the initial and final setting time. – Key Values; • Increase of free lime from 0.5% to 1.5%, initial and final setting time decreases for 40-50 minutes.

Addition of small amount of free lime • Makes the clinker

NERVOUS

Decrease of Free Lime and Setting Time

Initial Setting ( min. )

180 160 140 120 100

%

0.2

0.4

0.6

0.8

1

Free Lime in Clinker

1.2

1.4

1.6

Rule 5 • Increasing the C3S proportion of clinker develops the 1,2,3 and 7 day strength. After 28 days, strength development may be less because of C2S effect. – Key Values; • +10% C3S development.

+2 to 5 MPa early strength

In short and middle term,

MPa Gaining C3S increase 10% -10% C2S

+ 5 to 6 MPa.

STRENGTH (C3S)

60.0

R-28d

55.0 50.0

R-7d

N/mm 2

45.0 40.0 35.0

R-2d

30.0 25.0

R-1d

20.0 15.0 45.0

50.0

55.0

C3 S

60.0

Rule 6 Hard to Grind…

C2 S + 10 % C2S

+ 4 kWh/t

Grindability

D

Case 1

Case 2

94,50

98,60

+ 4,10

C3 S

56

64

+8

C2 S

22

15

-7

C3 A

10,20

9,60

=

C4 A F

8,20

8,00

=

Free. CaO

1,27

1,30

=

46,70

44,40

- 2,30

3680

3710

=

kWh/t Industrial

53,10

51,60

- 1,50

28 d. Industrial

32,0

35,5

+ 3,5

% LSF Clinker

kWh/t BB10 SSB BB10 ( cm2/g )

Rule 7 • Whatever the formation is, alkalis do not affect the 28 days strength positively. – Key Values; • +0.1% increase in equivalent Na2O

• -1 N/mm2 at 28 days

Effect of Alkalis

70

28 –days strength (MPa)

65 60 55 50 45 0

0.2

0.4

0.6

0.8

1

% Total Alkalis

1.2

1.4

1.6

1.8

2

Rule 8 • Regarding early strength, with the optimum sulphate content, soluble alkalis, especially alkali sulphates develops the early strength. – Key Values; – +0.1% Equivalent Na2O – +0.5 to 1.5 N/mm2 @ 1 day strength

ALKALI

1 K2O and 1 SO3 (MOLAR)

SULPHATES

1 K2SO4 (Soluble)

These soluble alkalis are good for 1-2 days strength.

Rule 9 • Change of crystal formation of C3A from cubic to orthorhombic, – – – –

Bad burnability, Process problems, Sensitivity to aging Decrease in 28 days strength.

Alkalis more than sulphates • Excess alkalis go into the crystal structure

Na2O, C3A

NC8A3

K2O, C2S

KC23S12

DECREASE IN 28 DAYS STRENGTH

Rule 10 • If the clinker SO3 amount is more the molar saturation rate, a significant increase is observed on clinker fineness and grindability. – Key Values; • +1% excess SO3

+5 kWh/t

SO3 > Na2O , K2O Dusty Clinker, More kWh/t Cement Grinding

+ 1% Excess SO3

+ 5 kWh / t

( @ 350 m2 / kg )

Excess Sulphates * Finer Clinker 100

% Passing

80 60

0,1 % S03

40

1,3 % SO3

20 0 0

5

10

15

Screen ( mm )

20

25

Excess Sulphates 100

60

0,1 % SO3 2,9 % SO3

40 20 0 5

10

15

20

25

30

35

Screen( mm )

* Finer Clinker

100 80

Passing

0

%

% Passing

80

60

0,1 % SO3

40

1,2 % SO3

20 0 0

10

20

30

40

Screen( mm )

50

60