View
3
Download
2
Category
Preview:
Citation preview
DALMIA REFRACTORIES LTDWELCOMES THE DELEGATES
AF COMPATIBLE & ENERGY SAVING ALUMINA REFRACTORIES
FOR CEMENT PYRO PROCESS
Contents
❖ Raw materials for Alumina bricks
❖ Impact of pet coke and suitable bricks
❖ Impact of alternate fuel and suitable bricks
❖ Special problem solving Alumina bricks
Crystal phases of Alumina-Silica refractories
Al O Range Common Phases Major Raw Material2 3
Less than 40%
Al O
Mullite and glass (can
contain "free SiO )Fireclay (Chamotte)
50% Al O or
60% Al O
Major phase - Mullite
Minor phase - Glass
Calcined Bauxite,
Sillimanite,
Andalusite & Fireclay
70% Al O
Major phase - Mullite
Minor phase - Corundum
and Glass
Calcined Alumina,
Andalusite,
Sillimanite, Fused
Alumina
80% and 85%
Al O
Major phase - Corundum
Minor phase - Mullite and
Glass
Calcined
Bauxite,Fused
Alumina
90% and 99%
Al O
Major phase - Corundum
With trace amount of
Mullite and Glass
Tabular Alumina,
Fused Alumina
2 3 2
2 3
2 3
2 3
2 3
2 3
Raw materials characterization in Alumina-Silica Refractories
Raw Material Al2O3(%) Charactersics
Chamotte (Calcined fireclay) 35-45 - Alkali resistance
Andalusite 55-60 - Shock resistance
Bauxite 80-90 - Abrasion resistance
Corrundum (Alumina) 99 - High refractoriness
Synthetic mullite (Calcined Bauxitic Clay) 60-70
- Strength,Thermal elasticity
Silicon carbide (SiC) - Coating resistance
Major Raw Materials
Synthetic Natural Calcined
Brown Fused Alumina Andalusite Calcined Bauxite
White Fused Alumina Sillimanite Lumps Fire clay
White Tabular Alumina Sillimanite Sand
Fused Mullite Raw Kyanite
Sintered Mullite Clays
Calcined Mullite Bauxite
Petcoke Firing - Advantages Vs Challenges
▪ High Calorific Value
▪ Low Ash Content
▪ More Stable in Storing &
transportation
▪ Less chance of
spontaneous combustion
▪ Less moisture absorption
▪ Low cost
▪ Increase in Sulphur - Require optimization
of clinker chemistry & monitoring A/S
ratio
▪ Hard to grind - Increases maintenance
cost on coal mill rollers, ducts, liners etc.
▪ Unstable coating conditions in kiln -
Lesser refractory life
▪ Build up Formation towards kiln inlet &
preheater - direct damage from build up
removal
Advantages Challenges
Refractory Requirement - Petcoke Firing
✓ High Thermal load bearing capability.
✓ Dense brick with less porosity/permeability
✓ Coating friendliness
✓ Chemical attack resistance
✓ Abrasion resistance.
Special Alumina bricks - DALBURN & DALSINT
PROPERTIES UNIT DALSINT A DALBURN
PCE Ort/OC Min 38/1850 Min 36/1820
RUL taOC Min 1520 Min 1600
RTE @ 1000OC % 0.60 0.60
PLC @ 1500/2 hrs % Max + 2.0 Max +1.0
Spalling Resistance at 1000OC AIR QUENCH
Cycles Min 80 Min 100
ALKALI PENETRATION @1100°C/5hrs
mm < 3.0 < 3.0
Thermal Conductivity w/mK ~1.9 2.20
A.P % Max 15 Max 17
B.D g/cc Avg. 2.70 Avg 2.70
CCS kg/cm2 Min 600 Min 700
Al2O3 % Min 70 Min 70
Fe2O3 % Max 2.0 Max 2.0
DALSINT - Major benefits
Excellent Spalling Resistance
➢ High grade raw materials and well engineered granulometry
➢ Air quenching (1000°C to Air) : + 80 cycles (Typical ~120)
➢ The Refractoriness under load (RUL) ofDALSINT A is >1520°C.
➢ This high thermal value will give youhigh thermal load bearing capability.
High Refractoriness under Load
➢ Resistance to Temperature Fluctuations.
➢ Resistance to hot face cracking
➢ Resistance to high flame temperature.
➢ High thermal elastic properties
DALSINT - Major benefits
High Cemical purity
➢ Manufactured from high pure Raw materials
➢ Very low Fe2O3 (2.0% Max) & lowalkalis (1.0 Max)
➢ Resistance to redox reactions
➢ Resistance to chemical corrosion
➢ Low porosity means low permeability& high strength
Very Low porosity
➢ Resistance to alkali penetration
➢ High abrasion resistance
➢ Low handling breakages
DALBURN - Major benefits
Excellent Spalling Resistance
➢ High grade raw materials and well engineered granulometry
➢ Air quenching (1000°C to Air) : + 100 cycles (Typical ~120)
➢ Resistance to Temperature Fluctuations.
➢ Resistance to hot face cracking
➢ The Refractoriness under load (RUL) ofDALBURN is >1670°C.
➢ This high thermal value will give youhigh thermal load bearing capability.
High Refractoriness under Load
➢ Resistance to high flame temperature.
➢ High thermal elastic properties
DALBURN - Major benefits
High Cemical purity
➢ Manufactured from high pure Raw materials
➢ Very low Fe2O3 (2.0% Max) & lowalkalis (1.0 Max)
➢ Resistance to redox reactions
➢ Resistance to chemical corrosion
➢ Low porosity means low permeability& high strength
Very Low porosity
➢ Resistance to alkali penetration
➢ High abrasion resistance
➢ Low handling breakages
➢ High heat transfer resistance
➢ Thermal conductivity @ 1000°C - ~2.2W/mK
Low thermal Conductivity
➢ Low Kiln Shell temperature
DALSINT & DALBURN - Other benefits
➢Supplied in ISO & VDZ shapes
➢Stringent dimensional tolerances - +/-1mm or 1% whichever greater
➢When compared to basic bricks
✓ Better inventory control – Indefinite shelf life
✓ Less supply time - 4 to 6 weeks
✓ Less Refractory load.
✓ Low shell temperature
Alternate Fuel - Main Challenges
➢ Excessive build-up or clogging (kiln inlet or gas riser )
➢ Build-up of abnormal kiln rings, resulting from unbalanced sulfate modulus
➢ Variations in oxygen potential - redox cycles
➢ Direct action of alkali chlorides and sulfates
➢ Fluctuations in flame length & Thermal wash-out
➢ Destabilization & stripping of clinker coating
➢ Abrasive clinker in outlet causing refractory outlet issue
Sulphate Alkali Ratio & Build-up
(SO3/80)Q (ASR) = ------------------------------------------
{(Na2O/62) + (K2O/94) + (Cl/71)} When Q = 1 Alkalis Salts are in balanced condition in environment
When Q > 1 Environment contains Alkali salts with Free SO3
When Q < 1 Environment contains Salts with Free Alkali Oxides
Impacts of Sulphur & Alkali
The most adverse effect of alternate fuel has been thedestructive forces of sulfur / alkali.
✓ Alkali penetration,
✓ Expansive refractory reactions and
✓ Brick spalling,
✓ Un-wanted Buildups
✓ Direct damage from buildup removals.
Refractory Requirements - AF firing
✓ Low lining porosity & high hot strength
✓ Wear resistance.
✓ Chemical attack resistance.
✓ Coating repellence.
✓ High resistance to thermal shock.
Coating Repellent Refractories
DRL has developed a range of SiC containing bricks, with rawmaterials ranging from fireclay, Andalusite, Mullite and Bauxite.
✓ Very High Chemical Resistance
✓ Minimize coating or ring build-up
✓ High hot strength
✓ Long service life
✓ Extreme abrasion resistance
DAL CR - 50
5 - 7% SiC
DAL CR - 60
13 - 17% SiC
DAL CR - 70
23 - 27% SiC
Phases Present & Abrasion Loss
Quality
XRD Phases Abrasion Loss**
(gm/cm2)Major Phases Minor Phases
DAL CR-70Silicon carbide,
Mullite, CorundumAndalusite, Cristobalite
0.05
DAL CR - 60Mullite,
Silicon carbide, CorundumAndalusite, Cristobalite
0.11
DAL CR - 50 Mullite, Silicon carbide Andalusite, Cristobalite 0.13
LF-70 - 20 Mullite, Corundum Cristobalite, Sillimanite 0.98
LF-60 -20 Mullite, Cristobalite, Sillimanite 1.09
LF-45 -25 Mullite, Cristobalite, Sillimanite 1.20
** By DIN 52108 (Bohme Disk Abrader) with 70mm cube.
DAL CR Bricks Technical details
PROPERTIES UNIT DAL CR50 DAL CR60 DAL CR70
Al2O3% 45 46 45
Fe2O3% 1.5 1.2 1.2
SiC 5.0 – 7.0 13.0 – 17.0 23.0 – 27.0
AP (Max) % 15.0 15.0 15.0
BD (Min) gm/cc 2.35 2.50 2.65
CCS (Min) Kg/cm2 600 500 600
PLC at 14500C % +0.6 +0.6 +1.0
RUL ta O C 1450 1550 1580
Thermal Conductivity @ 10000C
(Kcal/m/hr/0C
2.0 2.5 2.68
SPALLING @ 1000 O C [AQ ]
CYCLES + 100 +100 +150
AREA OF APPLICATION CZ/IZ SZ LTZ/SZ
DAL CR Bricks Application Area
➢ Cement production is highly energy Intensive process.
➢ Energy consumes 25-30% of the total cost.
➢ Out of the total energy 75% is the thermal energy.
➢ Around 20% of the total thermal energy goes as waste even after
implementing & practicing the energy efficient measures.
➢ Heat transfer mechanism is complicated as it includes conduction,
convection and Radiation
➢ Highest heat loss occurs through kiln shell
Energy Saving Solutions
SPECIAL FEATURES
➢ VERY LOW THERMAL CONDUCTIVITY
➢ LOW DENSITY
➢ GOOD STRENGTH
➢ RESISTANT TO ALKALI / SULPHUR ATTACK
ADVANTAGES
➢ REDUCTION IN RADIATION LOSSES
[ SHELL TEMPERATURE REDUCTION UPTO 750C ]
➢ REDUCTION IN REFRACTORY LOAD ON THE KILN
APPLICATION AREA
➢ KILN INLET ZONE
ALITE
TYPE : High strength Energy Saving Brick
APPLICATION : Calcination Zone of cement rotary kiln and other areas where radiation losses are to be minimized.
CHEMICAL COMPOSITION Al2O3 % Min. 20.00
Fe2O3 % Max. 2.50
PHYSICAL PROPERTIES
Apparent Porosity % Min. 30.0 Bulk Density g/cc Max. 1.75
Cold Crushing Strength kg/cm2 Min. 200
THERMAL PROPERTIES
R.U.L. ta C Min. 1300 P.L.C at 1200 C /2 hrs. % + 0.6
ALITE
ALITE - SOLUTION TO ENERGY SAVING
Residual thickness 190 to 200mm
ALITE after 10 months service
Rotary Kiln with Alumina bricks Lining
THANK YOU
Recommended