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Effects and impacts of components of coal handling system on coke quality and yield of coke plantsS. Steinbach, R. Neuwirth, Dr. R. Kim, ThyssenKrupp Industrial Solutions AG (TKIS), Germany
Motivation
Increased requirements for the quality of coke
A well designed coal handling system helps to improve the coke quality and to reduce the purchasing costs for coal at the same time
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Influencing Factors
• Grain size
distribution
• Coal moisture
• Additives
Summary
Plant Layout
• Blend crushing
concept
• Selective crushing
concept
Recommendations
• Selective screening
and crushing
• Coal moisture controle
Overview
Influencing Factors: Grain size distribution 1
normal raw coal has 30%
~ 50% of grain size < 3 mm
the caking ability of coal decreases when the fraction below 0.2 mm is increased
Separate grain size of4 ~ 6mm by screening before crushing to reduce the fraction below 0.2 mm
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Typical coal size distribution
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Ideal grain size distribution
size target ideal
<10 mm 100% 100%
< 3 mm 80~90% 100%
< 0.5 mm 34~40% 34%
*Simons W., Rubrecht E.: Optimaler Körnungsaufbau von Kokskohle, Essen, Germany, 1965
*
Influencing Factors: Grain size distribution 2
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GRAIN SIZE PERCENTAGEG
RA
IN S
IZE
*Simons W., Rubrecht E.: Optimaler Körnungsaufbau von Kokskohle, Essen, Germany, 1965
The higher the amount of small particles, the lower the bulk density
The bulk density influences the coke strength (M10 and M40)
Influencing Factors: Grain size distribution 3
Influencing Factors: Coal moisture 1
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Coal moisture control plants (CMCP) are common practice to control bulk density and reducing heating costs
Usual technologies are drum and fluidized drying
*Laske H.: Untersuchungsverfahren zur Charakterisierung fester Brennstoffe, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, Germany, 1961
*
Influencing Factors: Coal moisture 2
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Moisture control is recommended to stabilize to coking conditions
Optimum wall pressure can be achieved at 6% to 9% moisture content
*Deutsche Montan Technologie GmbH: Improved energy efficiency and coking process operation and control, Bulk density and internal gas pressure in large volume coke ovens, Germany, internal report
*
Influencing Factors: Additives
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0.1% ~ 0.5% of oil addition to the coal mixture, advantages:
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Increase of the bulk density without increasing the wall pressure
Flow of the charged coal characteristics are getting better
Reduces carry over
Less spillage coal amount
Overheating of the gas collecting space can be avoided
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Overview
Influencing Factors
• Grain size
distribution
• Coal moisture
• Additives
Summary
Plant Layout
• Blend crushing
concept
• Selective crushing
concept
Recommendations
• Selective screening
and crushing
• Coal moisture controle
Plant Layout: Blend crushing concept
Problems:
hard coals are not crushed sufficiently
soft coals are crushed to an extremely fine grain size
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COAL TOWERBLENDING BINS CRUSHER
Plant Layout: Selective crushing concept
Profit: Control of grain size, moisture and additives leads to stable coking conditions and a better coke quality
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DRYERBLENDING BINSCRUSHER MIXER COAL TOWERSURGE BIN SCREEN
Overview
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Influencing Factors
• Grain size
distribution
• Coal moisture
• Additives
Summary
Plant Layout
• Blend crushing
concept
• Selective crushing
concept
Recommendations
• Selective screening
and crushing
• Coal moisture controle
Selective crushing of each individual coal grade
Hard coking coals → coarse crushing
Hard coking coals + high swelling index → fine crushing
Softer coals → fine crushing
Particle size (<0.1 mm) → graphite deposits
→ carry-over
Recommendations for coal handling plants
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Fine grain >40% oiling →(0.1% ~ 0.5%) is advisable.
Pre-screening
Drying of coal to a constant moisture level
Combination of pneumatic classifying and drying upstream crushing.
Recommendations for coal handling plants
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Overview
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Influencing Factors
• Grain size distribution
• Coal moisture
• Additives
Summary
Plant Layout • Blend crushing
concept • Selective crushing
concept
Recommendations
• Selective screening and crushing
• Coal moisture controle
A well designed coal handling plant including:Pre-separation of fine particles before crushing
Selective crushing of each coal type
Coal moisture control
Mixing equipment for additives
Allows for:Use of increased portion of low-ranked coking coals
Reduction of cost for coal
Increase of coke quality
Improvement of coking conditions & battery life time
Summary
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Any questions?
For further information contact [email protected]
Thank you for your attention!
Simon SteinbachThyssenKrupp Industrial Solutions AG
17.06.2015