Transcript
Burning zone refractory failureK.P.PRADEEP KUMAR
The coating is thin and washed away from the brickSurface. Around 9 meter area.High variation in chemistry whenOPC clinker is switched over toOil well cement or sulfate resistant Cement. The second reason isFormation of distorted flame whichEroded the coating and brick. WithPetcoke firing the liquid becomes moreViscous and destruct the bricks.
SDCCL
The mag chrome got eroded due to high thermo-chemical load.Some how alumina bricks retain the coating and prolonged condition of
this condition would have damaged the alumina bricks too.
Perilex-83
Lofal -70
9 m area
SDCCL
Perilex bricks at 11.5 m.Bricks undergone severe thermal andThermo chemical srtesses due to variation in clinker Chemistry.Petcokeunder reduced conditions furtheraggravate the situation.
SDCCL
groove formation due to shell deformationOr wrong installation of key bricks. Key bricks must be just fit in .Too much hammering can cause damage. Not more thantwo Shims must be inserted in a ring with a gap of 3to 4 bricks.
SDCCL
Severe thermo-chemical ( high liquid %attack on the brick( lava formation)
Crack on the cold face shows thatthe brick was under severe mechanical stress tooShell distortion at 9 M causes mechanicalstresses on the brick.
Grooves on the shellAt 9 M length
SDCCL
Bulged portion of the shell at 9.0 m
Mortar applicationto correct thelining at 9.0 m
About 30 mm it has bulgedinwards which is wellbeyond the toleralance limits.9.0 m area. Maximum tolrenceLimit is +/- 10 mm.
SDCCL
Causes• Very high variation in clinker chemistry when converted OPC clinker to
oil well cement and sulfate resistant cement. Petcoke firing reduces the Viscosity of the liquid and further damage the bricks .
• Reduced conditions when petcoke is fired is extremely harmful to magchrome bricks.
• Oil spillage on the refractory bricks and damaged the magchrome bricks.Coal particles was also falling on the bricks while heating.
• Kiln was rotated in the cold conditions for maintenance purpose • Shell was bulged in the burning zone area.
Refractory failure in burning zone SDCCL
Remedies • Frequency of change over from OPC clinker to SRC and OWC can be
reduced by properly planning.• The burner needs replacement. Burner tip was damaged. Oxidised
conditions must prevail esp. when petcoke is fired.• Kiln shell need replacement at 9 M area• No job must be done after the lining is over for kiln rotation.
Melting pit
This happended during start-up , high percentage ofliquid forms. The hot aggressive liquid (Lava)attacked the bricks , and washed the brick surface. GCW
Bricks got soften and erodeddue to high liquid formationduring kiln start-up( lava)
GCW
Bricks got softenedand eroded. Very highPercentage of melt Formation( lava)
GCW
Thermo chemically attacked magchrome bricks. Sulfur penetrated the bricks.
Even the spinel brick is Penetrated by liquid ,in burning Zone, 8 – 15 M.Calculated liquid % is 33 .
APCW APCW
Burning zone refractory failure at GCW Causes• Excessive liquid formation, Lava during startup• Thick coating formation due to high liquid % in clinker• High thermal loading , >5.8 Gcal/sq M/hr• Petcoke was tried for some time. Magchrome bricks with petcoke firing gives
less life due to formation of low viscous liquid.Remedies• Care must be at the time of start-up. Flame intensity can be reduced in
the beginning to avoid over-heating.• When thermal load is high the kiln is very sensitive to chemistry variation• Hence variation in chemistry esp quartz must be controlled.• If Pet coke is used spinel bricks are better choice.
Note:If kiln runs stable with minimum variation in chemistry thermal load does not matteras coating on the bricks protects the bricks. But if the thermal loading is high and coating dislodges due to variation in chemistry or operational instability the consequent thermo-chemical load is more detrimental than the thermal load..
Refractory failure at 12 m After 4 months of operation. The spinel bricks underwent severe aggressive liquid attack.( 33 % liquid)
Liquid penetrated the spinel brick
Slice of the spinel brickAt 60 mm from the surface.
APCW
Hercynite based bricks are senstive to redox conditions.The white coloration is due to redox conditions prevailingIn the kiln. Flame needs attention. Picture taken at 7 M area
Avoid reduced conditions. Shape the flame to get convergent and hot flameOptimize the momentum . Momentum with low % primary and high velocity is always better than Momentum with % primary air and low velocity.
APCW
Burning zone refractory failure at APCW
• Excessive liquid , > 33% causes liquid penetration deep into the bricks anddestroy the texture of the brick , even the conventional spinel bricks.
• Reduced conditions make the coating very unstable. During coatingdislodgement it took away part of the brick.
Remedies• Optimise the liquid at around 30 -31 %.• Use fused spinel bricks Like Almag AF and Ankral R2• Shape the flame to avoid reduced condition• Dislodge the rhino horn by installing proper shock blasters.
Installation Errors
The brick rings arenot straight. Though We usepnemato-o-ring this error can occur. Human skill is also needed. Thisspinel brickscan undergomechanical stressesand reduce the refractory life.The lining was openedand was corrected.
Installation errorAPCW
After correcting the lining APCW
At 11 M
After starting the kiln within two days hot spot appeared.This V-gap formed due errors in installation. The brick ring must be perpendicular to the axis.
HCW
HCW
Thanks for your kind attention
K.P.Pradeep Kumar
top related