174113385-Alkali-Khaled.pdf

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The A lkal i Bypass


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Alkali Bypass


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Bypass - Wherefore ?

1. Improofed plant reliability- Reduction of Alkali concentration

- Reduction of coating build ups

- Reduction of production cost (Personal, cleaning work)

2. Improved clinker quality

- Reduction of alkali content of alkalis (z. B. Low - Alkali - Clinker)- Limititation of sulfur (cement quality)

- Limitation of Chlor content

3. Possibility of waste material burning

- economical interesting secondary fuels and raw materialscontents often high amount of harm components

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Cooling

Quenching chamber

Conditioning tower

Separation

Electro filter

Dust collection

Clean gas emission

Alkali Bypass

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Bypass

Hot Gas Duct

Quench Air

Bypass

Mixing

Chamber

Bypass

Mixed Gas

Polysius: Actual Bypass Design

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Velocity Distribution

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Air blaster

nozzles

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p g j g_ g _ _ g g g _ _ ppg

What are the minor elements ?

They are chemical components of the raw materials with a

low concentration towards the other components.

In the cement industry, Cl, SO3, Na2O and

K2O are, among others, particularly monitored

Although some have no impact on the chemical process, others might lead to major

troubles.

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What happens in the system ?

Raw Materials

Raw Meal

Grinding Heating up

Hot Meal

Clinker

Clinkerization

Volatilization

Temperature

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Condensation

Temperature



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Low volatilization

temperature

Extraction from

material

Flowing with

gases

Condensation on

cooler particles

Increase of

local

concentration

PROBLEMS

Problem with volatile elements

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What are some elements doing ?

Volatilization temperature

+Condensation temperature

2 cycles

Internal

Cycle

External

Cycle

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Internal and External Cycles

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Different behaviors

Chloride start evaporate around 650C

Alkalis start evaporate around 900C

Sulfur start evaporate around 1000C

Conclusion :

The various content of element is different according

to the analyzed area (kiln feed, meal cyclone 2, hot

meal, clinker,).

Nevertheless, most of the highest concentrations arelocated at the kiln inlet, depending on the salt

formation.

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Example of decision

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0

200

400

600

800

1000

1200

1400

1600

1800

0 5 10 15 20 25 30

Bypassrate (%)

gStb/Nm3Byp.HG

Texfa

Yamaver

Suezver

Berfa

Sakufa

Rugver 80

ECFA

1

2

K1

K2

3

Dust loading of bypass gas

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Decreases the concentration of minors

in the kiln inlet by taking out a part ofkiln gas

Taking part of the heat

Taking part of the production

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Calculation of V Kiln

The volume coming out of the kiln is composed by :

1. The volume of the gas combustion - V Comb

2. The volume of the decarbonation - V CO23. The volume of excess air - V Ex

ExV

COV

CombV

KiV

2ln

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Calculation of the bypass ratio

Finally, knowing V Kiln and V BP

lnKi

Bypass

V

V

RatioBypass

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Conclusion

Minor elements are to be considered foroperation decisions

Chemistry is able to help for any investigation

concerning the process troubles

The volatilization and cycles of the elements

can be handled through process operation

A good knowledge of the element circulation is

necessary for a good trouble shooting

Alkali Bypass

174113385-Alkali-Khaled.pdf

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