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Institute ™
Rotary Kiln Maintenance Seminar
Introduction
Institute ™Introduction 2
Introduction
Kiln Seminar Agenda Types of Kilns Systems The Clinker Production Process Terminology Kiln Safety
Institute ™Introduction 3
Kiln Seminar Agenda
Institute ™Introduction 4
Kiln Seminar Agenda
1. Introduction, Kiln Safety2. Kiln Shell3. Tires and Ovality4. Kiln Supports5. Kiln Bearings6. Kiln Drive7. Kiln Alignment8. Seals, Thrust Rollers,
Maintenance Schedule
Institute ™Introduction 5
Types of Kiln Systems
Institute ™Introduction 6
Pyro-processing System
The rotary kiln is part of the pyro-processing system.
4-Stage Preheater Calciner String
Calciner
Tertiary Air Duct Clinker
Cooler
Rotary Kiln
4-Stage Preheater Kiln String
Institute ™Introduction 7
SP ILC SLC
Preheater Arrangements
These are some of the many different configurations of preheaters that have been installed.
Institute ™Introduction 8
SP Preheater System
The SP (Suspension Preheater) system features four preheater cyclones. Most calcining is done inside the kiln. Some fuel (15%) may be added in the riser duct.
Fuel Consumption 800 Kcal/kg Clinker
Institute ™Introduction 9
ILC Calciner
The ILC (In Line Calciner) system adds a separate vessel for calcining. Up to 60% of total fuel may be added here. Raw meal entering the kiln is 92% calcined.
Fuel Consumption 700 Kcal/kg Clinker
Institute ™Introduction 10
SLC Calciner
The SLC (Separate Line Calciner) system has two preheater strings, one string attached to the kiln and a second string with calciner attached to the tertiary air duct.
Fuel Consumption 700 Kcal/kg Clinker
Institute ™Introduction 11
Wet Process System
In the wet process system, drying, preheating, calcining and burning are all done inside the kiln.
Fuel Consumption 1400 Kcal/kg Clinker
Institute ™Introduction 12
Rotax-2 Kiln
State of the art kiln technology
Two supports
production rates to 7500 mtpd
Tangential tire suspension
Gearless, friction drive
Self-aligning roller supports
Institute ™Introduction 13
The Clinker Production Process
Institute ™Introduction 14
Clinker Production
Limestone
Clay/Sand
Iron Ore
Clinker
CaCO3
SiO2 + Al2O3
Fe2O3
CO2
CaO
1650º F900º C
2650º F1450º C
Institute ™Introduction 15
Calcium Oxide CaO (C) 67%
Silicon Oxide SiO2 (S) 22%
Aluminum Oxide Al2O3 (A) 3.5%
Iron Oxide Fe2O3 (F) 3.5%
96%
Impurities 4%
100%
The Four Oxides of Cement Clinker
Clinker Production
Institute ™Introduction 16
Raw Materials
67% C
22% S
3.5% A
3.5% F
4% Impurities
100%
Clinker
67% C3S
14% C2S
5% C3A
10% C4AF
4% Impurities
100%
2650 ºF
1450 ºC
Clinker Production
Institute ™Introduction 17
Liquid phase
Free CaOCaCO 3
Quartz
Clays
C S2
C S3
C A3
C AF4
Clinker Production
Inside the kiln, the iron and alumina melt to form a flux in which the calcium and silica dissolve. Upon cooling the mixture crystallizes into clinker.
Institute ™Introduction 18
Terminology
Institute ™Introduction 19
Kiln Terminology
1 Rotation, as seen from discharge hood
2 For FLS and Fuller kilns, pier numbering starts at discharge end
3 Bearing right and left a seen from discharge end
Kiln Pier
Inlet Seal
Support Roller
Drive Pier
Kiln Shell
Discharge Hood
Inlet Hood
GearTire
Outlet Seal
Rotation1
Pier 1 2
Tertiary Air Duct
Pier no. 3 Right Uphill Bearing 3
Institute ™Introduction 20
1. Preheater Top Stage2. Downcomer Duct3. Kiln Seal4. Preheater Intermediate Stage 5. Preheater Intermediate Stage6. Preheater Lower Stage7. Rotary Kiln8. Induced Draft Fan9. Kiln Burner10. Clinker Cooler11. Cooler Vent System
System Terminology
Institute ™Introduction 21
Kiln Safety
Institute ™Introduction 22
Preheater Flush
Never work anywhere on a kiln system while a preheater vessel is plugged. If the plug breaks free it will rush like water through the system, burning everything in its path.
Institute ™Introduction 23
Preheater Flush
These men were working inside a kiln when a preheater flush occurred. Two fatalities resulted.
Institute ™Introduction 24
These men were working outside a clinker cooler when a preheater flush occurred, spewing hot material through an open man-door. Two fatalities resulted.
Preheater Flush
Institute ™Introduction 25
Protective Clothing
When working with hot dust a complete fireproof suit must be worn.
Institute ™Introduction 26
Hot Dust
Hot dust can unexpectedly blow out through any opening in the system. Keep doors and ports closed! Hot dust can ignite flammable materials in the area.
Institute ™Introduction 27
Dust Hazard
Be careful around kiln seals. Hot dust can blow out during process upsets. Kiln dust also contains lime, which can burn skin and eyes.
Institute ™Introduction 28
Dust Hazard
Know where your shower and eyewash stations are!
Institute ™Introduction 29
Fall Protection
Always wear your safety harness when working above ground.
Institute ™Introduction 30
Heights
High places can be dizzying. Always tie off with a safety belt.
Institute ™Introduction 31
Air Blasters
Air blasters are often placed near the kiln inlet and outlet. They must be disabled when working nearby.
Kiln Inlet Hood Cooler Inlet
Institute ™Introduction 32
Air Blasters
Discharge the Tank
Shut off the Air
Lock Out the Air Valve
Test That the Tank is
Empty
Institute ™Introduction 33
Lockout/Tagout
Follow your plant’s safety lockout procedures. Lock out all equipment affecting the area in which you are working.
Institute ™Introduction 34
Drive Guards
All moving parts must be completely guarded.
Institute ™Introduction 35
Roller Guards
Kiln rollers are nowadays completely guarded. Note that the old practice of running lead wire between tires and rollers to check alignment is no longer encouraged.
Institute ™Introduction 36
Coating Collapse
Do not work under loose kiln coating.
Institute ™Introduction 37
Kiln Rollback
Due to the feed material being dragged up one side of the kiln as it turns, an offset load exists which tries to make the kiln rotate backwards.
Load Center of Gravity
Institute ™Introduction 38
Kiln Roll-Back
The backstop can be released manually to allow the kiln to roll back. Warning! Rolling back too fast can explode the inching drive and cause serious injury. Keep a lock on the release switch to prevent unauthorized use.
Safety Padlock
Release Switch
Institute ™Introduction 39
Electrical Safety
When working inside a kiln make sure electrical cables do not short out on the kiln shell.
Institute ™Introduction 40
Rigging Safety
Before making heavy lifts, make sure you have received the necessary rigging training.
Institute ™Introduction 41
Carbon Dioxide
Carbon dioxide is a normal product of the biological process, but too much CO2 can kill.
Institute ™Introduction 42
Carbon Dioxide
Kiln exhaust gas contains approximately 35% CO2. This heavier-than-air gas tends to accumulate in low lying areas. Make sure all enclosed areas are properly vented before entering.
Institute ™Introduction 43
Combustibles
Lock out all fuel systems before entering the kiln.
Institute ™Introduction 44
Steam Explosions
Use of water around a kiln can be deadly. Water coming into contact with hot kiln feed or clinker can vaporize in an instant, causing a steam explosion. Especially, be careful around wet process kilns.
Institute ™Introduction 45
This man was working in a clinker transport tunnel when hot material flushed out into standing water in the elevator pit. He was killed by the steam explosion.
Steam Explosions
Institute ™Introduction 46
Questions?
Institute ™
Rotary Kiln Maintenance Seminar
Kiln Shell
Institute ™Introduction 48
Shell Details
Kiln Crank
Measuring Kiln Crank
Heat Correction of Kiln Crank
Shell Repair
Shell Welding
Submerged Arc Welding
Kiln Shell
Institute ™Introduction 49
Shell Details
Institute ™Introduction 50
Shell Details
Inlet Cone
Outlet Shroud
Tire No. 1
Tire No. 2
Tire No. 3
40 mm40 mm
40 mm (gear)
75 mm(under tire)
50 mm
30 mm 30 mm 30 mm
80 mm(under tire)
75 mm(under tire)
40 mm
Typical shell plate thicknesses.
Institute ™Introduction 51
Kiln Crank
Institute ™Introduction 52
Kiln Crank
Kiln crank occurs when a kiln shell is not perfectly straight. As the shell turns, cyclical loads and stresses occur in the shell and the kiln supports.
Institute ™Introduction 53
Kiln Crank
Kiln crank can cause severe cyclical loads, leading to shell cracks and fatigue cracks in the roller shafts.
Institute ™Introduction 54
Kiln crank will result in gear misalignment which can destroy gear teeth.
Kiln Crank
Institute ™Introduction 55
Kiln Crank
Kiln crank can be temporary, as in the case of a rain warped shell, or permanent, as in the case of a shell damaged by heat blisters.
Institute ™Introduction 56
Kiln Crank
When a hot kiln is stopped during a heavy rainstorm, one side of the shell cools off and contracts, causing a concave up curvature.
Institute ™Introduction 57
Kiln Crank
When a hot kiln is stopped too long without rotation, heat will rise and the top of the shell will expand, causing a convex-up curvature.
Institute ™Introduction 58
Kiln Crank
Irregular coating formation or refractory wear can cause one side of the shell to heat up more than the other. The result is a temporary crank in the shell.
Institute ™Introduction 59
Kiln Crank
Damaged refractory will cause a hot spot in the shell.
Institute ™Introduction 60
A hot spot left unattended will wrinkle the shell and create a crank. Refractory bricks will no longer stay in place and the shell section will have to be replaced at great expense.
Kiln Crank
Institute ™Introduction 61
Heat Damaged Kiln Shell
A heat-wrinkled kiln shell will also shorten the kiln, causing tires to run off-center.
Institute ™Introduction 62
Kiln Crank
Kiln crank can be caused by poor alignment of kiln sections during assembly or repair.
Institute ™Introduction 63
Kiln Crank
Kiln crank can be caused by weld shrinkage at a temporary shell patch.
Institute ™Introduction 64
Measuring Kiln Crank
Institute ™Introduction 65
Measuring Kiln Crank
Kiln crank can be identified by measuring roller deflection. The load on the roller will change as the kiln turns and this results in bending of the roller shaft.
Institute ™Introduction 66
A roller that deflects cyclically with kiln rotation by over 0.3 mm typically indicates a crank in the shell that should be repaired.
Measuring Kiln Crank
Institute ™Introduction 67
Measuring Kiln Crank
Kiln crank can be measured by measuring shell run-out. A polar diagram is generated on which the deviation from the true kiln center can be seen.
Institute ™Introduction 68
A series of polar diagrams gives a picture of the shell crank.
Measuring Kiln Crank
Institute ™Introduction 69
Heat Correction of Kiln Crank
Institute ™Introduction 70
Heat Correction of Kiln Crank
A kiln shell can sometimes be straightened by heat correction. Insulation is wrapped around the shell, allowing the shell steel to overheat. Shell stresses then diminish as the kiln sags into place on the rollers.
Institute ™Introduction 71
Temperature sensors are installed to carefully monitor shell temperatures beneath the insulation during the correction process.
Heat Correction of Kiln Crank
Institute ™Introduction 72
Heat Correction of Kiln Crank
Institute ™Introduction 73
Shell Repair
Institute ™Introduction 74
Shell Repair
Major shell defects are normally repaired by replacing the damaged section. The band-aid approach is at best a temporary solution.
Institute ™Introduction 75
Field Joint Hardware
New shell sections are joined with adjustable erection lugs.
Institute ™Introduction 76
Shell Alignment
By adjusting the erection lugs the shell sections are straightened until a perfect centerline is achieved.
Institute ™Introduction 77
Tire Handling
Institute ™Introduction 78
Shell Rigging
Institute ™Introduction 79
Shell Rigging
Institute ™Introduction 80
Shell Handling
Institute ™Introduction 81
Spider Bracing
Institute ™Introduction 82
Spider Bracing
Institute ™Introduction 83
Spider Bracing
Institute ™Introduction 84
Shell Stiffening Rings
Many older kilns had shell stiffening rings. These rings would eventually cause shell cracks due to heat expansion. Field-cutting expansion slots may help this problem.
Institute ™Introduction 85
Shell Welding
Institute ™Introduction 86
Joint Preparation
Prior to welding the shell plate ends are carefully prepared.
Institute ™Introduction 87
Weld Shrinkage
The 60º double V weld results in less shrinkage and less weld metal being required. Weld distortion is minimized, avoiding the “gull-wing” effect.
Institute ™Introduction 88
Weld Shrinkage
Institute ™Introduction 89
Shell Welding
Institute ™Introduction 90
Shell Welding
After completing the outside weld, the root pass is removed using carbon arc gouging.
Institute ™Introduction 91
Shell Welding
After gouging, the joint is carefully cleaned and inspected to ensure that no defects from the root pass remain.
Institute ™Introduction 92
Shell Welding
When welding is finished, the joint is inspected radiography or ultrasound. Defects are marked and then repaired.
Institute ™Introduction 93
Submerged Arc Welding
Institute ™Introduction 94
Submerged Arc Welding
Institute ™Introduction 95
Submerged Arc Welding
Institute ™Introduction 96
Submerged Arc Welding
Institute ™Introduction 97
Submerged Arc Welding
Institute ™Introduction 98
Submerged Arc Welding
Institute ™Introduction 99
Submerged Arc Welding
Institute ™Introduction 100
Submerged Arc Welding
Institute ™Introduction 101
Submerged Arc Welding
Institute ™Introduction 102
Submerged Arc Welding
Institute ™Introduction 103
Submerged Arc Welding
Institute ™Introduction 104
Submerged Arc Welding
Institute ™Introduction 105
Submerged Arc Welding
Institute ™Introduction 106
Submerged Arc Welding
Institute ™Introduction 107
Submerged Arc Welding
Institute ™Introduction 108
Submerged Arc Welding
Institute ™Introduction 109
Submerged Arc Welding
Institute ™Introduction 110
Submerged Arc Welding
Institute ™
Rotary Kiln Maintenance Seminar
Tires and Ovality
Institute ™Introduction 112
Tires and Ovality Tires and Tire Mounting Tangential Suspension Tire Clearances Ovality Tire Creep and Top Clearance Correcting Ovality Tire Pad and Stop Block Repairs Tire Crack Repair
Institute ™Introduction 113
Tires and Tire Mounting
Institute ™Introduction 114
Kiln Tire Support System
Tires are mounted over support pads with machined O.D.’s. Precise clearances are maintained to allow for different rates of expansion between kiln tire and kiln shell.
Machined SurfaceMachined
Surface
Institute ™Introduction 115
Pads are not welded to the shell, but are trapped in place by guide bars. Stop blocks are welded on one side only, alternating from one side to the other.
Tire Attachment
Institute ™Introduction 116
Tire Attachment
A loose stop ring is placed between the stop block and the tire. Wear takes place on the replaceable ring, not on the stop blocks.
Stop Ring
Stop Block
Guide Bars
Machined Support Pad
Institute ™Introduction 117
Tire Attachment
This shows a slightly different version of the floating pad, stop ring design.
Institute ™Introduction 118
Bolted Support Pads
Some FLS kilns have bolted support pads. Bolting avoids heavy welds which lead to shell cracks. The above arrangement uses a wear ring between stop blocks and tire.
Institute ™Introduction 119
Bolted Support Pads
This arrangement for smaller, light duty kilns uses stop blocks directly against the tire, i.e., without the use of wear rings.
Institute ™Introduction 120
On kilns without wear rings, when the blocks eventually wear down, they have to be cut off and new ones re-welded.
Tire Attachment
Institute ™Introduction 121
Tangential Suspension
Institute ™Introduction 122
Tangential Suspension
The tire is fixed and does not creep inside the shell. Shell expansion is accommodated with a system of spring-loaded wedges.
Institute ™Introduction 123
Tangential Suspension
Tangential suspension reduces ovality. Forces on the shell are tangent rather than radial.
Institute ™Introduction 124
Tangential Suspension
Brackets are bolted onto the tire. “Dog bones” keep the tire in position. Wedges keep the brackets tight against the dog bones. Springs keep the wedges tight as dimensions change with heat expansion.
Tire Bracket
“Dog Bone”
Wedge
Spring
Institute ™Introduction 125
Tangential Suspension
Tire Bracket“Dog Bone”
Wedge
Spring Rod
Wedge Retainer
Institute ™Introduction 126
Tangential Suspension
A completed tire section ready for installation.
Institute ™Introduction 127
Tangential Suspension
Wedges are held in position with retainer brackets bolted to the top of the “dog bones”.
Institute ™Introduction 128
Tangential Suspension
The spring rod pushes the wedge in to maintain a tight fit between dog bones and brackets as the kiln shell expands and contracts.
Institute ™Introduction 129
Tangential Suspension
As the wedges wear, the spring length increases. Periodically, check the distance and adjust the spring tension as required.
Institute ™Introduction 130
Tangential Suspension
“Dog bones” are attached to the shell with heavy welds. Periodically inspect the welds for cracks.
Institute ™Introduction 131
Tangential Suspension
Tire bolts are hydraulically tightened to specification.
Institute ™Introduction 132
Hydraulic Bolt Tensioning Tool
Institute ™Introduction 133
Tire Clearance
Institute ™Introduction 134
Tire Clearance
Tires are mounted over support pads with machined O.D.’s. Precise clearances are maintained to allow for different rates of expansion between kiln tire and kiln shell.
Machined Surface
Institute ™Introduction 135
Tire Clearance
It is necessary to have clearance between the tire support pads and tire I.D. to accommodate heat expansion of the shell. Cold clearance is typically 6-12 mm for a new kiln, depending on the location of the tire.
Normal Cold Clearance
Institute ™Introduction 136
Tire Clearance
The shell will heat up faster and expand more than the tire, and clearance will diminish. Normal hot running clearance should be from 0 to 3 mm (⅛”).
Normal Hot Running Clearance, 0-3 mm
Institute ™Introduction 137
Rate of Expansion
Example. A kiln shell with 5 meter (5000 mm) diameter at 20º C is heated to 320º C. The shell expands
5 meters x (320 - 20) = 15 mm
100
Rule of Thumb
Expansion of Steel (approx):
1mm / Meter/ 100ºC
Institute ™Introduction 138
Ovality
A kiln shell is not stiff enough to support its own weight. When placed on the ground it collapses to an oval shape.
Institute ™Introduction 139
Ovality
When placed inside a rigid tire the shell’s deformation is reduced, but it will still collapse if there is any clearance present. The amount it collapses depends on the amount of clearance and on the stiffness of the shell.
Institute ™Introduction 140
Shell and Tire Deformation
Shell deformation also occurs because the tire is not absolutely rigid. Due to elasticity of both shell and tire, the actual top clearance is 1.5 to 2 times the difference in diameter.
Perfectly Round
Shell and Tire
Deformed Shell and Tire
Difference in diameters
Actual Top Clearance
Institute ™Introduction 141
Ovality and Brick Problems
Kiln shell ovality causes continuous flexing of the brick lining as the kiln turns.
Institute ™Introduction 142
Excessive ovality will damage the refractory lining, typically with scattered spalling and single brick fall-out among otherwise undamaged areas.
Ovality Refractory Damage
Institute ™Introduction 143
Shell Cracks Due to Ovality
Excessive ovality may cause longitudinal cracks in the shell beneath the tires.
Institute ™Introduction 144
Shell Cracks Due to Ovality
This shell crack was caused by excessive ovality. The heavy welding used to attach the support pad was a contributing factor.
Institute ™Introduction 145
Definition of Ovality
Dh
Dv
Absolute Ovality = Dh - Dv
Relative Ovality = (Dh – Dv )/D
Different definitions of ovality are in use. This definition takes into account both shell and tire deformation. Ovality is usually expressed in percent.
Institute ™Introduction 146
Relative Ovality
= 0
(shell is round)
Relative Ovality
> 0
(shell is deformed)
Relative Ovality
Institute ™Introduction 147
Ovality Limits
Ovality as a function of kiln diameter. Exceeding these limits will cause refractory and shell problems.
Institute ™Introduction 148
Heating the kiln up too fast can result in bottle-necking (pinching) of the shell inside the tire. Excessive heating, i.e., after loss of refractory under the tire, will also cause bottlenecking.
Causes of Excessive Ovality
Institute ™Introduction 149
Causes of Excessive Ovality
Because of its massive size, the tire will change temperature more slowly than the shell. If the kiln is heated up too fast the shell will become restricted inside the tire and deformation will result.
Institute ™Introduction 150
After the shell becomes deformed and temperatures return to normal, there will be excessive running clearance and ovality, resulting in refractory damage.
Excessive Running Clearance
Causes of Excessive Ovality
Institute ™Introduction 151
Measuring Ovality
The shell-test device measures the kiln shell’s actual radius of curvature during rotation. From this data the shell stresses can be precisely calculated.
Institute ™Introduction 152
Measuring Ovality
Institute ™Introduction 153
Measuring Ovality
Institute ™Introduction 154
Measuring Ovality
Shell-test device
Institute ™Introduction 155
Ovality (%) = 4D² x 100%
3dn
Ovality Calculation
D = outside diameter of the shell at the test location (meters)
dn = nominal inside diameter of the shell (mm)
= /15, deflection measured from the shell test diagram (mm)
Institute ™Introduction 156
Sample Calculation
Tire #1, Station #1, Downhill
ovality (%) = 4D² x 100%
3dn
ovality (%) = 4(3.727m)²(12mm/15) x 100%
3(3657.60mm)
ovality (%) = 0.406%
Ovality
Institute ™Introduction 157
Tire Creep and Top Clearance
Institute ™Introduction 158
Because of the slight difference in diameter between the tire ID and shell (support pad) OD, the shell rolls inside the tire as the kiln turns. This gives the appearance that the shell is “creeping’ inside the tire.
Creep
Institute ™Introduction 159
Place a chalk-mark on the tire and another right next to it on the shell. After one revolution, measure the distance between the two marks. This distance is the creep.
Measuring Creep
Creep
Institute ™Introduction 160
Creep is the difference in circumference. Therefore,
Measuring Creep
Creep
Creep
= Difference in Diameter
Institute ™Introduction 161
Top clearance depends on the difference in diameter and on the shell stiffness. The stiffness factor is normally between 1.5 and 2.0, depending on how thick the shell plate is.
Top Clearance
Top Clearance = Difference in Diameter x Stiffness Factor
Institute ™Introduction 162
Measuring Creep and Top Clearance
Top clearance and creep can be measured with this simple device.
Institute ™Introduction 163
Measuring Creep and Top Clearance
Institute ™Introduction 164
This is a data sheet of 5 kiln revolutions. The distance between waves is the creep. The height of the wave is the top clearance. Always record tire and shell temperatures and identifying data (kiln no., tire no., date).
Measuring Creep and Top Clearance
Institute ™Introduction 165
Measuring Creep and Top Clearance
Institute ™Introduction 166
Measuring Creep and Top Clearance
Institute ™Introduction 167
Correcting Ovality
Institute ™Introduction 168
Correcting Ovality
Excessive clearance can be removed with the installation of shims beneath the support pads.
Shims
Institute ™Introduction 169
Shim thickness is calculated to give a hot running clearance of about 3 mm (⅛”).
Correcting Ovality
Shim
Institute ™Introduction 170
If the kiln shell becomes deformed it is necessary to replace the tire section. Ovality can be reduced by installing temporary pads with filler plates, but bricks will never fit properly on the inside of the kiln shell.
Correcting Ovality
Institute ™Introduction 171
Correcting Ovality
Institute ™Introduction 172
Correcting Ovality
Institute ™Introduction 173
Correcting Ovality
Institute ™Introduction 174
Correcting Ovality
Institute ™Introduction 175
Correcting Ovality
Institute ™Introduction 176
Correcting Ovality
Institute ™Introduction 177
Correcting Ovality
Institute ™Introduction 178
Correcting Ovality
Institute ™Introduction 179
Correcting Ovality
Institute ™Introduction 180
Correcting Ovality
Institute ™Introduction 181
Correcting Ovality
Institute ™Introduction 182
Correcting Ovality
Institute ™Introduction 183
Correcting Ovality
Institute ™Introduction 184
Correcting Ovality
Institute ™Introduction 185
Correcting Ovality
Institute ™Introduction 186
Tire Pad and Stop Block Repairs
Institute ™Introduction 187
Regularly inspect the supporting pads and stop blocks for weld cracks and repair at the next kiln stop. Waiting too long will only cause problems to compound.
Tire Pad and Stop Block Repairs
Institute ™Introduction 188
Tire Pad and Stop Block Repairs
Replace stop blocks when wear becomes excessive. Do not use shims as shown, as they probably won’t last.
Institute ™Introduction 189
Excessive stop block wear on the thrust tire is especially problematic since it can affect the gear’s position on the pinion.
Tire Pad and Stop Block Repairs
Institute ™Introduction 190
Tire Pad and Stop Block Repairs
Heavy welds directly on supporting pads frequently crack due to temperature fluctuations and fatigue stress. The floating pad design solves these problems.
Institute ™Introduction 191
Floating Tire Pad Design
Institute ™Introduction 192
Wear Ring Installation
Wear Rings
Anti-Rotation
Bars
Institute ™Introduction 193
Wear Ring Installation
Institute ™Introduction 194
Wear Ring Installation
Institute ™Introduction 195
Fractures at Shell Pads
Institute ™Introduction 196
Fractures at Shell Pads
Institute ™Introduction 197
Fractures at Shell Pads
Institute ™Introduction 198
Fractures at Shell Pads
Institute ™Introduction 199
Fractures at Shell Pads
Institute ™Introduction 200
Tire Crack Repair
Institute ™Introduction 201
Ultrasonic Inspection of Tires
Institute ™Introduction 202
Tire Repair Welding
Institute ™Introduction 203
Tire Repair Welding
Institute ™Introduction 204
Tire Repair Welding
Institute ™Introduction 205
Tire Repair Welding
Institute ™Introduction 206
Tire Repair Welding
Institute ™Introduction 207
Tire Repair Welding
Institute ™Introduction 208
Tire Repair Welding
Institute ™Introduction 209
Tire Repair Welding
Institute ™Introduction 210
Tire Repair Welding
Institute ™
Rotary Kiln Maintenance Seminar
Kiln Supports
Institute ™Introduction 212
Kiln Supports
Types of Kiln Supports Roller Adjustments Roller Inclination Roller and Tire Defects Roller and Tire Re-conditioning
Institute ™Introduction 213
Types of Kiln Supports
Institute ™Introduction 214
Rigid Kiln Support
A kiln support consists of two rollers with bearings mounted on a base frame. This rigid support is the most common.
Institute ™Introduction 215
Self-Aligning Kiln Support
Tire
Roller
Bearing
Hinge
Pivot Point
On this support the bearings are mounted on a pivoting frame.
Institute ™Introduction 216
Self-Aligning Kiln Support
A self aligning support maintains continuous contact between tire and roller as the kiln turns. As a result, there is less hertz pressure on the roller and components can be sized more economically.
Self-aligning support
Traditional Rigid Support
Institute ™Introduction 217
Self-Aligning Kiln Support
Institute ™Introduction 218
FLS Kiln Support Type SRB
Institute ™Introduction 219
FLS Kiln Support Type RA
FLS kilns have supports with self aligning bearings in spherical sockets.
Hornos FLS han soportes con cojinetes auto alineación en los zócalos esférica.
Institute ™Introduction 220
FLS Kiln Support Type RB
The RB support is similar to the RA support, except the bearing takes the thrust load next to the roller on a thrust ring.
Institute ™Introduction 221
Fuller Kiln Support
The Fuller support has rigid bearings.
Institute ™Introduction 222
Roller Adjustments
Institute ™Introduction 223
Axial Forces on a KilnLas fuerzas axiales en un horno
A kiln on a slope will tend to move downhill as it turns. That downward movement is resisted by both the friction force between rollers and tires, and by the force on the thrust roller.
Un horno en una pendiente tenderá a moverse hacia abajo a medida que gira. Ese movimiento hacia abajo es resistido tanto por la fuerza de fricción entre los rodillos y neumáticos, y por la fuerza en el rodillo de empuje
2 - 4% slope
Friction ForceLa fricción de la Fuerza
ThrustRoller Force
Kiln’s Downhill Force Horno de descenso de la Fuerza
Institute ™Introduction 224
Roller Friction Force Rodillo de la fuerza de fricción
When a kiln roller is not exactly parallel to the kiln axis, it imparts an axial thrust force to the kiln. The direction of this force (uphill or downhill) depends on how the roller is skewed, and on the direction of kiln rotation.
Cuando un horno de rodillos no es exactamente paralelo al eje del horno, que imparte una fuerza de empuje axial en el horno. La dirección de esta fuerza (hacia arriba o hacia abajo) depende de cómo el rodillo es sesgada, y en el sentido de rotación del horno.
Neutral
Neutral
Institute ™Introduction 225
Roller Adjustment Counter-Clockwise Kiln
Horno de rodillos de ajuste contra el sentido del reloj
To reduce the load on the thrust roller, all rollers should be skewed to push the kiln uphill, never downhill. Shown above are the correct adjustments for a kiln that turns counter-clockwise (looking from the burner floor).
Para reducir la carga en el rodillo de empuje, los rodillos deben estar sesgadas para impulsar el horno cuesta arriba, nunca hacia abajo. Arriba se muestran los ajustes correctos para un horno que se vuelve hacia la izquierda (mirando desde el piso del quemador).
Direction of Kiln ThrustDirección de empuje del horno
Institute ™Introduction 226
Roller Adjustment Clockwise Kiln
Ajuste de rodillos Las agujas del reloj del horno
Direction of Kiln ThrustDirección de empuje del horno
These are the correct adjustments for a clockwise turning kiln.
Estos son los ajustes correctos para un horno de las agujas del reloj girando.
Institute ™Introduction 227
Roller Adjustment Ajuste de rodillos
Rollers on the discharge pier are often adjusted for neutral thrust. This avoids excessive roller wear caused by dust from the kiln seal.
Rodillos en el muelle de descarga se han ajustado para el empuje neutral. Esto evita el desgaste excesivo de
rodillos causado por el polvo de la junta de horno.
Neutral
Neutral
Feed End
Discharge End
Institute ™Introduction 228
Good Roller AdjustmentBuen ajuste de rodillos
All Rollers Pushing Uphill
All Rollers Pushing Equally
Kiln Floating Between Upper and Lower Thrust Rollers (or, correct pressure on hydraulic thrust cylinder)
*Todos los rodillos empujar cuesta arriba*Todos los rodillos de presionar igualmente*Horno flotante entre el Alto y el Bajo rodillos de empuje (o, la presión correcta en el cilindro de empuje hidráulico)
Institute ™Introduction 229
Roller -Tire ForcesFuerzas rodillo-neumático
When the force on the tire/kiln is uphill, the force on the roller is downhill. The direction of thrust can be determined by observing the contact or gap at the thrust stop inside the bearing.
Cuando la fuerza en el neumático / horno es cuesta arriba, la fuerza sobre el rodillo es cuesta abajo. La dirección de empuje se puede determinar mediante la observación del contacto o la brecha en la parada de empuje dentro del rodamiento.
Direction of Kiln Thrust
Institute ™Introduction 230
Bearing Thrust Arrangements
FLS Type RA
Takes Thrust Load on Thrust CollarToma de carga axial de empuje del collar
FLS Type RB
Takes Thrust Load on Thrust RingToma de carga axial en el anillo de empuje
Fuller
Takes Thrust Load on Thrust WasherToma de carga de empuje en la arandela de empuje
UphillBearingTeniendo cuesta
arriba
Downhill Bearing
Teniendo descenso
Institute ™Introduction 231
Bearing Thrust ArrangementsTeniendo Régimen de empuje
FLS Type RA
FLS Type RB
Fuller
Contact
Contact
Contact
Gap
Gap
Gap
Direction of Force on Kiln
Dirección de la fuerza de Horno
Direction of Force on Roller
Dirección del Trabajo sobre rodillo
Institute ™Introduction 232
FLS Bearing Type RAFLS RA Tipo de cojinete
The RA bearing takes the thrust load on a thrust plate which is bolted to the end of the shaft.
El cojinete de la RA tiene la carga de empuje en una placa de empuje que se atornilla al extremo del eje.
Thrust Collar
De empuje del collar
Institute ™Introduction 233
FLS Bearing Type RA
Institute ™Introduction 234
FLS Bearing Type RB FLS RB Tipo de cojinete
The RB bearing takes the thrust load at a ring which is shrunk onto the shaft.
El rodamiento RB tiene la carga de empuje en un anillo que se contrae en el eje.
Thrust Ring
Anillo de empuje
Institute ™Introduction 235
FLS Bearing Type RB
Institute ™Introduction 236
Fuller Bearing
The Fuller bearing takes the thrust load on a thrust washer which is bolted onto to the housing end cover.
Thrust Washer
Institute ™Introduction 237
FLS Bearing Type RA
The direction of roller thrust in an RA bearing is determined by observing the gap between thrust plate and bronze bearing liner. Contact in the uphill bearing and a gap in the lower bearing indicates that the roller is pushing the kiln uphill.
La dirección de empuje del rodillo en un cojinete de la RA se determina mediante la observación de la brecha entre la placa de empuje y el revestimiento del cojinete de bronce. Contacto en el cojinete hacia arriba y una brecha en el rodamiento inferior indica que el rodillo está empujando hacia arriba el horno.
Institute ™Introduction 238
FLS Bearing Type RA
For FLS bearings type RA, there should always be contact between thrust plate and bronze bearing liner on the uphill bearing. This indicates that the roller is pushing the kiln uphill.
Para FLS tipo de rodamientos de la AR, siempre debe haber contacto entre la placa de empuje y el revestimiento del cojinete de bronce en el cojinete hacia arriba. Esto indica que el rodillo está empujando hacia arriba el horno.
Contact
Institute ™Introduction 239
FLS Bearing Type RB
Direction of roller thrust in an RB bearing is determined by observing the gap/contact between thrust ring and bronze bearing liner.
Institute ™Introduction 240
FLS Bearing Type RB
For FLS bearings type RB, there should always be contact between thrust ring and bronze bearing liner on the downhill bearing. This indicates that the roller is pushing the kiln uphill.
Contact
Thrust Ring
Bearing Liner
Institute ™Introduction 241
FLS Bearing Type RB
For FLS bearings type RB, a gap should always be present on the uphill bearing. This indicates that the roller is pushing the kiln uphill.
Gap
Institute ™Introduction 242
Fuller Bearing
For Fuller bearings, thrust direction is checked by rapping the bearing end cover with a hammer. A solid sound indicates contact, a hollow sound indicates a gap.
Institute ™Introduction 243
Measuring Roller Thrust
Important! Rollers and tire surfaces must be completely free of oil when skewing adjustments are made. Only graphite block lubrication is permitted.
Graphite Block
Institute ™Introduction 244
Rollers should be adjusted to “float” the kiln between the upper and lower thrust rollers.
Roller Adjustment
Institute ™Introduction 245
For kilns with hydraulic thrust rollers, support rollers are adjusted to keep the hydraulic pressure within specification.
Pressure Gage
Roller Adjustment
Institute ™Introduction 246
The force on the thrust roller can be calculated from the hydraulic pressure indicated on the gage.
Hydraulic Pressure
Force = Pressure x AreaArea = (Piston Diameter) 2 x
4
Institute ™Introduction 247
Calculation of Hydraulic Pressure When All Rollers Are Neutral
• Calculate the weight of the rotating parts of the kiln (shell, tires, gear, refractory, material load).
• Multiply by the % kiln slope to get the force on the thrust roller.• Divide by the total piston area of all thrust rollers.
Example:• 1000 short ton kiln x 2,000 pounds/short ton = 2,000,000 pounds• 2,000,000 pounds x 3% slope = 60,000 pounds force on thrust roller
• Area of single 10” diameter piston = (10) 2 x = 78.5 inches 2
4
Pressure = 60,000 = 764 PSI78.5
Institute ™Introduction 248
Roller Adjustment
Rollers are skewed by moving bearings in or out as required. Note that the adjusting screws shown are greased and wrapped to prevent corrosion.
Institute ™Introduction 249
Jacks for Roller Adjustment
Pancake Jacks are available with forces over 100 tons to aid in pushing bearings in for roller adjustment.
Institute ™Introduction 250
Roller Adjustment
Moving a bearing out is easier. A small jack may be needed.
Institute ™Introduction 251
• Always measure and record every bearing adjustment. To keep from changing the kiln center, make equal and opposite movements on each bearing.
Roller Adjustment
Institute ™Introduction 252
Measuring Roller Thrust
Measuring precise roller thrust is possible on FLS bearings using this “axial measuring device”.
Institute ™Introduction 253
The axial measuring device consists of a hand jack with pressure gage, a mounting fixture, and an adapter with bearing to enable readings when the roller is turning.
Measuring Roller Thrust
Institute ™Introduction 254
Measuring Roller Thrust
The jack is pumped up until the roller begins to move uphill off its thrust stop. At this point a pressure reading is taken and the reading is then converted to tons force.
Institute ™Introduction 255
FLS
Type RB
FLS
Type RA
Data assumes a jack piston with 16.6 cm2 surface area.
Institute ™Introduction 256
Measuring Roller Thrust
Caution! It may not be possible to accurately measure roller thrust if tire and roller surfaces are not cylindrical or if roller shafts or bearings are grooved.
Step-worn Roller and Tire Grooved Roller Shaft
Institute ™Introduction 257
Determining Roller ThrustTrial and Error Method
Find the roller’s neutral point (parallel to kiln axis) by adjusting the roller skew in small increments until the bearing thrust contact/gap changes from one bearing to the other.
Once the neutral point is determined, make a small adjustment to push the kiln uphill.
While making an adjustment of an individual roller, always observe the kiln’s thrust rollers to ensure that they are not being overloaded.
Institute ™Introduction 258
Roller Inclination
Institute ™Introduction 259
Roller Inclination
Just like horizontal skewing, vertical skewing of a roller, i.e., having a roller slope different than the kiln slope, will also create a thrust force.
Institute ™Introduction 260
Roller Inclination
Roller slope must not deviate from the kiln slope by more than 0.02% (0.04% for old kilns). The direction of allowable deviation must be such that the roller pushes the kiln uphill.
Institute ™Introduction 261
Measuring Roller Slope
Roller slope is measured with an inclinometer.
Institute ™Introduction 262
Inclinometer
100 mm Spacing
1 mm micrometer
scale
Due to its dimensioning, the inclinometer reads the percent slope directly.
Institute ™Introduction 263
Inclinometer
When the leveling bubbles are centered, the percent slope is read on the micrometer dial.
Institute ™Introduction 264
Inclinometer
Magnets allow mounting the inclinometer on horizontal or vertical surfaces. The inclinometer has a precision bubble level for each position.
Institute ™Introduction 265
Inclinometer
Check the roller slope with the inclinometer mounted on the shaft end. Take readings on both ends of the shaft and average them to eliminate the effect of roller shaft deflection.
Institute ™Introduction 266
Inclinometer
This arrangement can be used to measure the roller slope while the kiln is turning.
Institute ™Introduction 267
Inclinometer
Using an inclinometer on a precision straight edge across a kiln base to determine the correct slope.
Institute ™Introduction 268
Roller and Tire Defects
Institute ™Introduction 269
If kiln rollers are skewed too much the wear rate can be quite severe.
Tire and Roller Defects
Institute ™Introduction 270
Excessive hertz pressures on under-designed or poorly cast tires and rollers can result in severe pitting.
Tire and Roller Defects
Institute ™Introduction 271
The old practice of running a roller in a water bath is now thought to promote surface pitting and is no longer recommended.
Tire and Roller Defects
Institute ™Introduction 272
Tire and Roller Defects
When rollers are misaligned or conical-shaped, the kiln load is spread over too small an area. This causes high surface stresses resulting in pitting.
Cuando los rodillos están desalineados o de forma cónica, la carga del horno se extiende sobre la zona son demasiado
pequeñas. Esto hace que la superficie de alta tensiones resultantes de las picaduras.
Institute ™Introduction 273
Tire and Roller Defects
A defect on a roller may transfer to the tire, and vice-versa.
Un defecto en un rodillo puede transferir a la llanta, y viceversa
Institute ™Introduction 274
Tire and Roller Defects
Roller or tires may wear to a conical shape.
Rodillo o llantas pueden llevar a una forma cónica
Institute ™Introduction 275
Tire and Roller Defects
A tire running off the roller for a long time will wear into a step pattern.
Un neumático corriendo el rodillo durante mucho tiempo se gastará en un paso patrón
Institute ™Introduction 276
Tire and Roller Defects
Tire wobble can create a concave roller surface.
Bamboleo de neumáticos puede crear una superficie del rodillo cóncavo
Institute ™Introduction 277
Roller and Tire Re-conditioning
Institute ™Introduction 278
Roller and Tire Re-conditioning
Rollers and tires may be re-conditioned by machining or grinding. Shown above is a lathe adapted for this purpose.
Rodillos y los neumáticos pueden ser re-acondicionado por maquinado o esmerilado. Arriba se muestra un torno adaptados para este fin.
Institute ™Introduction 279
Roller and Tire Re-conditioning
Rollers are re-conditioned while the kiln is in operation.
Los rodillos son re-acondicionado, mientras que el horno está en funcionamiento
Institute ™Introduction 280
Roller and Tire Re-conditioning
Machining a kiln tire while the kiln is in operation.
Mecanizado de un neumático del horno, mientras que el horno está en funcionamiento
Institute ™Introduction 281
Roller and Tire Re-conditioning
The machinist is protected with a heat shield.
El maquinista está protegido con un escudo térmico
Institute ™Introduction 282
Roller and Tire Re-conditioning
This roller is being resurfaced by grinding rather than machining.
Este rodillo se resurgido por desgaste en vez de mecanizado
Institute ™Introduction 283
Roller and Tire Re-conditioning
Re-surfacing a tire by grinding
Re-pavimentación de un neumático por desgaste
Institute ™Introduction 284
Tire and roller edge defects must also be removed. Edges should then be chamfered.
Roller and Tire Re-conditioning
Institute ™
Rotary Kiln Maintenance Seminar
Kiln Bearings
Institute ™Kiln BearingsIntroduction 286
Kiln Bearings
FLS Bearing Type RA - 1958 Design
FLS Bearing Type RB - 1974 Design
Fuller Bearing
Institute ™Introduction 287
FLS Kiln Support Type RA
FLS kilns have supports with self aligning bearings in spherical sockets.
Institute ™Introduction 288
FLS Bearing Type RA
Spherical Socketwith Water Jackets
Heat Shield
Bronze Bearing
Liner
Thrust Plate
Oil Scoop
Oil TrayOilScraper
Oil Level Gage
Felt Oil Seal
Institute ™Introduction 289
FLS Bearing Type RA
Stop Block
Water Piping
Inspection Port
Heat Shield
Institute ™Introduction 290
Type RA Oil Seal and Scraper
Rubber Oil
Scraper
Felt Seal
Institute ™Introduction 291
FLS Bearing Type RA
Institute ™Introduction 292
Inspection Ports
Oil FlowOil Flow
Thrust Contact/Gap
The FLS type A bearing has three inspection ports for monitoring lubrication and thrust direction.
Institute ™Introduction 293
Oil Tray
Oil scoops dip into the sump and carry oil into the oil tray. Holes in the tray allow oil to drip onto the shaft. The tray slope is adjustable to permit downhill flow of oil.
Tray
Scoops
Slope Adjusting
Screws
Institute ™Introduction 294
FLS Kiln Support Type RB
The RB support is similar to the RA support, except there is no thrust plate and the bearing takes the thrust load on a thrust ring.
Thrust Ring
Institute ™Introduction 295
FLS Bearing Type RB
Oil Scoops
Oil SealAdjustable
Oil Tray
Bearing Base
End Cover with
Inspection Door
Spherical Socket with Water Jacket
Bronze Bearing Liner
Thrust Ring
Institute ™Introduction 296
FLS Bearing Type RB
Heat Shield
Inspection Port
Water Piping
Oil TrayTemperature
Detector
Dowel Pin
Retainer Clamp
Institute ™Introduction 297
The RB bearing has a split rubber oil seal which requires monthly greasing.
Grease Fitting
Type RB Oil seal
Institute ™Introduction 298
FLS Bearing Type RB
Institute ™Introduction 299
Fuller Kiln Support
The Fuller support has rigid (non-spherical) bearings.
Institute ™Introduction 300
Fuller Bearing
Thrust Washer
End Cover
Inspection Port
Oil Tray
Oil Scoop
Oil Level Indicator
Bronze Bearing Liner
Institute ™Introduction 301
Bearing Liners
Institute ™Introduction 302
FLS Bearing Liner Details
Institute ™Introduction 303
Liner Clamps
Liners and sockets are clamped to prevent from rotating out of the housing.
Institute ™Introduction 304
Liner Clearance
Liner side clearances should be checked with a feeler gage at all four liner corners after installing a new liner.
Institute ™Introduction 305
Bearing Tolerances
Institute ™Introduction 306
Bearing Tolerances
Side Clearance
Oil Film
Insufficient side clearance will prevent oil from being drawn into the bearing. Excessive side clearance will result in the load being spread over too small an area, with a reduction of the oil film thickness at the bottom of the shaft.
Institute ™Introduction 307
Checking Liner Contact
Before installation of a new liner, apply Prussian blue to the shaft to check liner to shaft contact. The liner, installed in the socket, is lowered onto the shaft and slid back and forth longitudinally to pick up the dye at the liner contact points.
Institute ™Introduction 308
Checking Liner Contact
A well-fitting liner will pick up the blue only in the center down its entire length.
Institute ™Introduction 309
Checking Liner Contact
This liner shows less than full contact along its length, indicating a high spot in its center.
Institute ™Introduction 310
Checking Liner Contact
High spots are removed by scraping the bronze away at the heavily blued areas.
Institute ™Introduction 311
Bearing Lubrication
Institute ™
Lubrication Film
Tiny surface asperities are kept from contacting each other by a good oil film.
Institute ™
Hydrodynamic Lubrication
As one surface slides over another, a wave of oil wedges them apart, creating an oil film.
Institute ™
Hydrodynamic Lubrication
When the shaft rotates, oil is drawn in between the journal and bearing. The shaft lifts and a lubrication film is established.
Institute ™
Elasto-hydrodynamic Effect
Under extreme forces, plastic deformation occurs and surface area in the contact zone increases. Lubricant viscosity multiplies under extreme pressure. The result is a thin but stable oil film capable of keeping surfaces separated.
Institute ™
Boundary Lubrication
When speed or oil viscosity is too low, or when loads are excessive, surfaces may contact. Boundary lubrication conditions are said to exist.
Institute ™
EP Additives
Extreme pressure and anti-wear additives in the oil react to the high heat and pressures at the surfaces to form a low-friction chemical film, thus preventing surfaces from seizing.
Institute ™Introduction 318
Oil Film Thickness
Oil film thickness increases with viscosity and speed and decreases with load. A good film thickness is three times the surface roughness.
L =
Institute ™Introduction 319
Viscosity
Viscosity, or the resistance of a liquid to flow, is the most important property of lubricating oil. Oil viscosity changes drastically with temperature.
Institute ™Introduction 320
Viscosity
Oil viscosity is selected based on equipment operating temperature range.
Institute ™Introduction 321
Viscosity Index
Viscosity index is a relative measurement of how viscosity changes with change in temperature. Oil with a higher viscosity index can maintain its viscosity over a wider temperature range.
Institute ™Introduction 322
ISO Viscosity Grade
• International Standards Organization designation for oil viscosity grade.
• Measured as Centistoke (cSt) at 40º C.
• Becoming more common than SSU (Saybolt Seconds Universal).
• Multiply ISO VG by 5 to approximate SSU at 100º F.
Institute ™Introduction 323
Viscosity Equivalents
Institute ™Introduction 324
Kiln Bearing Lubricants
• Gear oils with EP additives
• Viscosity ambient temperatureISO VG 460 below 5º CISO VG 680 above 5º C
• Synthetic oils are preferred over mineral oils, due to their increased viscosity index, lower pour point and effectiveness at high temperatures.
Institute ™Introduction 325
Oil Level Indicator
Check oil level daily. Note that the level in the uphill bearing indicator is different than in the downhill bearing. Make sure that the oils scoops dip into the oil.
Institute ™Introduction 326
Inspection of Oil Flow
At start-up, especially after a long shutdown, oil is added manually to ensure that there is lubrication before rotation starts.
Institute ™Introduction 327
Bearing Lube Pump
Bearings can be equipped with lube pumps to provide oil to the tray prior to kiln start-up.
Institute ™Introduction 328
Bearing Circulating Lube System
A circulating lube unit can filter and cool the bearing oil. This one-pump unit serves one kiln support. It is equipped with four flow switches, one for each bearing of the two-roller support.
Institute ™Introduction 329
Bearing Temperature RTD
Oil film temperature can be measured with an RTD (resistance temperature detector), which slides over the journal as the shaft turns. Temperatures above 80ºC indicate a lubrication problem
Institute ™Introduction 330
Hot Bearings
Check cooling water supply. Check that a bearing heat shield is in place. Check oil cleanliness. Check the oil viscosity. Switch to a higher viscosity
(ISO V.G. 1000) if oil temperature exceeds 80-90ºC. Use synthetic oil instead of mineral oil. Check thrust load and reduce by adjusting roller
skew accordingly. Check liner smoothness. Replace if necessary. Check shaft smoothness. Re-machine if necessary. Check liner to shaft contact.
Institute ™Introduction 331
Lubrication Failure
Institute ™Introduction 332
Lubrication Failure
Institute ™Introduction 333
Severe Lubrication Failure
Institute ™Introduction 334
Catastrophic Lubrication Failure
Institute ™Introduction 335
Catastrophic Lubrication Failure
Institute ™Introduction 336
Catastrophic Lubrication Failure
Institute ™Introduction 337
Catastrophic Lubrication Failure
Institute ™Introduction 338
Catastrophic Lubrication Failure
Institute ™Introduction 339
Rigging
Institute ™Introduction 340
Rigging for Fuller Roller Assembly
Institute ™Introduction 341
Rigging for Fuller Bearing
“Feed End” Stamp
Institute ™Introduction 342
Bearing End Cover Removal
Bearing inspection can be facilitated by the preparation of two 24” rods on which to slide off the end cover.
Institute ™Introduction 343
Rigging for FLS Bearing Liner
Institute ™Introduction 344
FLS Kiln Support Type RA
Warning! Do not use cover lifting eyes to lift FLS bearings. They are designed only to lift the covers off the bearing housing.
Lifting Eyes for Cover Only!
Institute ™
Rotary Kiln Maintenance Seminar
Kiln Drive
Institute ™Introduction 346
Kiln Drive
Gear and Pinion Drive
Friction Drive
Hydraulic Friction Drive
Coupling Basics
Institute ™Introduction 347
Gear and Pinion Drive
Reversible Pinion
Jack Shaft
Main Reducer
Tandem Variable Speed Motors
Tacho-meter
Motor Cooling Fans
Fixed Bearing
Free Bearing
Institute ™Introduction 348
Kiln Inching Drive
Backstop
Inching Drive Reducer
One-way Clutch
Inching Drive Motor
The inching dive arrangement permits a rotation of approximately once every 10 minutes. A one-way clutch prevents over-speeding when the main drive is in operation. A backstop prevents kiln roll-back.
Institute ™Introduction 349
Kiln Drive
A jackshaft is used to improve the layout of the drive pier. This one is equipped with gear couplings.
Institute ™Introduction 350
Pinion Alignment
The pinion must be positioned so that pitch circles are tangent, and there is full face contact across the width of the teeth.
Pinion Pitch Circle
Gear Pitch Circle
Institute ™Introduction 351
Axial Alignment
The gear and pinion must have full face contact when the kiln is hot. It may be necessary to move the thrust rollers or reposition the thrust tire stop blocks to achieve this.
Institute ™Introduction 352
Inching Drive
Main Reducer
One-Way Clutch Backstop
Inching Drive
ReducerInching Motor
Institute ™Introduction 353
One-Way Clutch
The one-way clutch prevents over-speeding of the inching drive by locking the input and output shafts in one rotational direction only.
Institute ™Introduction 354
One-Way Clutch
Automatic Transmission
Fluid
Most one-way clutches have locking steel pawls inside, which require lubrication with automatic transmission fluid only.
Institute ™Introduction 355
Kiln Rollback
•Due to the feed material being dragged up one side of the kiln as it turns, an offset load exists which tries to make the kiln rotate backwards.
Load Center of Gravity
Institute ™Introduction 356
Backstop
The backstop prevents kiln roll-back. Most backstops aslo have locking steel pawls inside, which require lubrication with automatic transmission fluid.
Institute ™Introduction 357
Backstop
The backstop can be released manually to allow the kiln to roll back. Warning! Rolling back too fast can over-speed and destroy the inching drive. Keep a lock on the release switch to prevent unauthorized use.
Safety Padlock
Release Switch
Institute ™Introduction 358
Pinion Bearing Oil Lubrication
Bearing oil level should be sufficient to cover half of the lowermost rolling element. Note that the indicator may show different levels, depending on whether it is mounted on the uphill or downhill side of the housing.
Oil Level Sight Glass
Institute ™Introduction 359
Pillow Block BearingStabilizing
Ring for Fixed Bearing only
No Stabilizing Ring for Free
Bearing
Oil Level
Institute ™Introduction 360
Kiln Drive
This drive arrangement has a jack shaft with flexible disc couplings. The backstop is integrally mounted on the inching drive reducer.
Institute ™Introduction 361
Friction Drive
Institute ™Introduction 362
Friction Drive
Motors turn the rollers, and friction between rollers and tires turns the kiln. There is no kiln gear. Friction drive is used only on new two-support kilns.
Institute ™Introduction 363
Friction Drive
Both rollers are driven. The motors are balanced to prevent slippage.
Institute ™Introduction 364
Friction Drive
The reducer is shaft mounted. The inching drive with integral backstop is mounted directly on the main reducer. The main motor is coupled with a Cardan shaft. The inching drive motor has a fluid coupling.
Institute ™Introduction 365
Friction Drive
A special torque arm is used to prevent reducer rotation while still permitting movement of the roller shaft.
Institute ™Introduction 366
Hydraulic Friction Drive
A friction drive may use a hydraulic motor to turn the rollers.
Institute ™Introduction 367
Hydraulic Drive
Advantages
High starting torque
High degree of controllability
Even load sharing between rollers
Space savings
No reducer necessary (when using radial piston motors)
Shaft mounted, simplified foundation
Institute ™Introduction 368
Hydraulic Friction Drive
This hydraulic drive uses an axial piston motor and a planetary reducer mounted on the roller shaft.
Institute ™Introduction 369
Hydraulic Friction Drive
Shaft-mounted planetary reducer with torque, with integral hydraulic motor and inching drive.
Institute ™Introduction 370
Hydraulic Friction Drive
This hydraulic drive uses four radial piston motors mounted directly on the roller shaft.
Institute ™Introduction 371
This Hagglunds radial piston motor develops extremely high torque, and a reducer is therefore not needed.
Hydraulic Friction Drive
Institute ™Introduction 372
Hydraulic Friction Drive
The load is equally shared and each roller receives the same power and torque.
Institute ™Introduction 373
Hydraulic Friction Drive
The typical kiln drive will have multiple pumps for increased efficiency.
Institute ™Introduction 374
Hydraulic Friction Drive
Hydraulic drive power curve.
Institute ™Introduction 375
Hydraulic Friction Drive
DC drive power curve.
Institute ™Introduction 376
Hydraulic Friction Drive
Hydraulic drive power losses.
Institute ™Introduction 377
Hydraulic Friction Drive
DC drive power losses.
Institute ™Introduction 378
Couplings
Institute ™Introduction 379
Coupling Alignment
Couplings must be precisely aligned to minimize parallel and angular misalignment.
Institute ™Introduction 380
Coupling Alignment
Imprecise alignment will cause shock and vibrations to be transmitted to motor and machine bearings, resulting in reduced bearing life and possible equipment damage.
Institute ™Introduction 381
Coupling Alignment
Couplings are usually aligned with a dial indicator.
Institute ™Introduction 382
Coupling Alignment
Align the coupling as accurately as possible to promote long bearing life (not just to within coupling manufacturer’s specs).
Institute ™Introduction 383
Coupling Alignment
The coupling gap can be checked with a feeler gage. Gap specifications are normally found on the equipment foundation drawing, or in the coupling manufacturer’s data.
Feeler Gage
Institute ™
Laser Alignment
Laser alignment offers the most accurate and easiest coupling alignment.
Institute ™Introduction 385
Laser Alignment
A laser beam on one coupling half reflects back onto a sensor from a mirror on the other half. Misalignment is read on a hand-held computer.
Institute ™Introduction 386
Laser Alignment
Aligning a kiln inching drive with laser alignment method.
Institute ™
Rotary Kiln Maintenance Seminar
Kiln Alignment
Institute ™Introduction 388
Alignment Principles
Internal Alignment
Hot Kiln Alignment
Kiln Alignment
Institute ™Introduction 389
Alignment Principles
Institute ™Introduction 390
Kiln Alignment
A kiln is considered aligned when the center of rotation of the kiln shell at every support lies on a straight line.
Institute ™Introduction 391
Kiln Alignment
Note that a kiln with only two supports is always aligned, as there is always a straight line between two points.
Two Support Kiln
Institute ™Introduction 392
Kiln Alignment
A kiln can be misaligned in the horizontal or in the vertical plane.
Horizontal Axis
Vertical Axis
Institute ™Introduction 393
Consequences of Misalignment
Misalignment changes the loading on the kiln supports and causes overstressing of the shell and supports.
3597 kN 7048 kN 2815 kN
3902 kN 6491 kN 3067 kN
10 mm
Institute ™Introduction 394
Misalignment can result in all of the load being concentrated on one roller.
Consequences of Misalignment
Institute ™Introduction 395
Internal Alignment
Institute ™Introduction 396
Internal Alignment
Internal alignment is normally used when assembling a new kiln. A line of sight is shot through batter boards marking the kiln centers at the shell section ends and at the tire locations.
Institute ™Introduction 397
New kiln sections usually have steel spider bracing with precisely marked centers. If not, wooden batter boards can be prepared.
Internal Alignment
Institute ™Introduction 398
Internal Alignment
The kiln shell’s center is found by scribing four arcs on a target card tacked onto the batter board.
Institute ™Introduction 399
Internal Alignment
Drawing diagonals at the arcs’ intersections will locate the center.
Institute ™Introduction 400
Internal Alignment
Removable targets with marked shell centers are placed at each tire center and shell end. The theodolite’s line of sight is marked on the target and the offset is measured.
Institute ™Introduction 401
Kiln Alignment
Note that if there is any top clearance present, the tire center is not the same as the kiln center. Alignment calculations must take hot running clearance into account.
Tire centre
Kiln centre
S
Top Clearance
Institute ™Introduction 402
Roller Adjustment
Field Joint Adjustment
After measurements are taken the kiln is aligned by adjusting rollers and field joints.
Correcting Misalignment
Institute ™Introduction 403
Correcting Misalignment
Moving both rollers horizontally will move the kiln center by the same amount.
h
h
h
Institute ™Introduction 404
Roller adjustments to correct vertical alignment can be calculated from the relationship of right triangles.
A
B
C
B
C
A2 + B2 = C2
Correcting Misalignment
Institute ™Introduction 405
Correcting Misalignment
Moving one roller horizontally will move the kiln center horizontally by half and vertically by one quarter (approximately) of the distance.
1
½
¼
Institute ™Introduction 406
Correcting Misalignment
Caution! Moving a roller on the piers immediately uphill and downhill from the kiln gear will affect the gear alignment.
Institute ™Introduction 407
Hot Kiln Alignment
Institute ™Introduction 408
Measurements and corrections can be completed while the kiln is operating.
The data collected indicates the real conditions as the kiln is operating.
Alignment errors can be corrected immediately or during a planned kiln outage.
Advantages
Hot Kiln Alignment
Institute ™Introduction 409
Mechanical Hot Kiln Survey Method
Laser Kiln Survey (LKS) Method
Hot Kiln Alignment
Institute ™Introduction 410
Diameter of support rollers and live rings using electro-mechanical instrument.
Temperature of the support rollers, live rings and kiln shell.
Creep and clearance between the kiln shell support pads and live rings.
Both methods utilize a variety of measured data to determine kilns axis:
Hot Kiln Alignment
Institute ™Introduction 411
Using a theodolite to establish a line of sight along the kiln, the horizontal distances from the line of sight to each support roller is measured.
Mechanical Alignment
Institute ™Introduction 412
Using an optical level the elevations of the bearing base frames are determined.
Mechanical Alignment
s
f
j
F
a b
cq
cleft cright
Tire centre
Kiln centre
dleft dright
Institute ™Introduction 413
Elevation markers on kiln piers should be checked to see if a kiln pier has sunk.
Mechanical Alignment
Elevation Markers
Institute ™Introduction 414
Roller and Tire Circumference
Using a precision measuring wheel and tachometer the circumference of the roller and tire are measured.
Institute ™Introduction 415
DIGITAL CIRCUMFERENCE OF TIRE
A magnet and magnetic sensor record start/stop positions. Circumference is read on the digital readout to 0.1 mm accuracy.
Magnet
Roller and Tire Circumference
Institute ™Introduction 416
Line of sight
Using the measurements, and knowing the distance between supports, a kiln centerline can be constructed which best fits the existing roller positions.
Mechanical Alignment
Institute ™Introduction 417
s
f
j
Fa b
cq
cleft cright
dleft dright
Mechanical Alignment
Institute ™Introduction 418
Laser Kiln Survey
Tire elevation and location can be determined utilizing a laser theodolite from ground level.
Institute ™Introduction 419
Laser Kiln Survey
Laser measurement provides the most accurate method of kiln alignment.
Kiln Center Tolerances
Horizontal Plane 1.5 mm
Vertical Plane 2.5 mm
Institute ™Introduction 420
Laser Kiln Survey
Institute ™Introduction 421
Laser Kiln Survey
Institute ™Introduction 422
Laser Kiln Survey
Institute ™Introduction 423
Laser Kiln Survey
Institute ™Introduction 424
Questions?
Institute ™
Rotary Kiln Maintenance Seminar
Kiln Miscellaneous
Institute ™Introduction 426
Kiln Inlet Seal
Kiln Outlet Seal
Thrust Roller
Hydraulic Thrust Roller
Kiln Maintenance Checklist
The Good Old Days
Kiln Miscellaneous
Institute ™Introduction 427
Kiln Inlet Seal
Institute ™Introduction 428
Kiln Inlet Seal
The kiln seal prevents cold air from entering the process and driving up fuel costs. The seal must remain tight while accommodating kiln run-out and longitudinal movement.
Institute ™Introduction 429
Kiln Pneumatic Inlet Seal
The pneumatic seal consists of two sliding surfaces pushed together by pneumatic cylinders.
Pneumatic Cylinders
Institute ™Introduction 430
Kiln Inlet Seal
Spring Loaded Graphite Plug
Seal Detail
Pneumatic Cylinders
Institute ™Introduction 431
Kiln Inlet Seal Detail
Graphite Seal Cord
Wire Rope
Graphite Plugs
Rotating Kiln Shell
Rotating Sealing Surface
Stationary Sealing Surface
Sliding Contact
Stationary Kiln Inlet Hood
Institute ™Introduction 432
Kiln Inlet Seal
The seal is suspended by a carriage which allows it to move longitudinally as the kiln expands and contracts.
Carriage
Turnbuckle
Institute ™Introduction 433
Pneumatic Inlet Seal
The pneumatic cylinders, when pressurized, will press the two seal halves tightly together.
Stationary Seal Half
Rotating Seal Half
Institute ™Introduction 434
Filter, Regulator, Lubricator
Cylinder force is controlled by adjusting the air pressure. A lubricator prevents cylinder corrosion and seize-up. The filter keeps condensation and dirt out of the cylinder.
Institute ™Introduction 435
Filter, Regulator, Lubricator
Institute ™Introduction 436
Kiln Inlet Seal
The seal’s sliding surfaces are graphite lubricated.
Spring Loaded Graphite Plug
Graphite Plugs in Seal Plate
Institute ™Introduction 437
Kiln Inlet Castings
Castings on the inlet hood and kiln inlet cone keep the castable refractory in place. Inspect them at annual shutdown.
Institute ™Introduction 438
Spring Plate Inlet Seal
Institute ™Introduction 439
Spring Plate Inlet Seal
Institute ™Introduction 440
Spring Plate Inlet Seal
Institute ™Introduction 441
No, covering the spring plates with plastic won’t help.
Spring Plate Inlet Seal
Institute ™Introduction 442
Outlet Seal
Institute ™Introduction 443
Kiln Outlet Seal
The spring plate outlet seal has become the outlet seal of choice. The seal can withstand the harsh conditions at the kiln hood.
Institute ™Introduction 444
Kiln Outlet Seal
Spring Plate Wire Rope
Institute ™Introduction 445
Kiln Outlet Seal
Counterweight
Spring plates are wrapped with a counterweighted wire rope arrangement to keep them tight against the cowl.
Institute ™Introduction 446
Forced Air
Cooling
Kiln Outlet Seal
A stainless steel cowl at the kiln outlet provides an air channel for cooling of the kiln discharge castings and the spring plate contact surface.
Institute ™Introduction 447
Kiln Outlet Seal
Spring plates are bolted on and are easily replaced.
Institute ™Introduction 448
Kiln Outlet Seal
Dust from kiln hood puffing falls down the chutes to the drag chain conveyor or into the clinker cooler.
The Old Way The Better Way
Institute ™Introduction 449
Kiln Outlet Sector
The kiln nose rings sees severe service and must be regularly inspected for refractory and casting failure.
Institute ™Introduction 450
Kiln Outlet Seal
This alternate spring plates design features outwardly protruding spring plates.
Institute ™Introduction 451
Kiln Outlet Seal
Outwardly protruding spring plate design.
Institute ™Introduction 452
The Most Expensive Seal
A bad seal allows cold air into the kiln. The cost of extra fuel to heat this cold air can amount to tens of thousands of dollars per year.
Institute ™Introduction 453
Thrust Roller
Institute ™Introduction 454
Thrust Roller Assembly
Oil Seal
Oil Level Pipe
Spherical BearingsTie
Rod
Tire
Shims
Clearance
Keep the clearance to a minimum (6mm), and adjust the shims to keep the kiln gear in proper longitudinal alignment.
Institute ™Introduction 455
Thrust Roller Assembly
Set Screws
The kiln position can be controlled by adjusting set screws on this thrust roller base.
Institute ™Introduction 456
Thrust Roller Position
Stop Ring
Thrust Tire
The thrust roller is positioned to maintain proper hot running alignment between kiln gear and pinion. Repositioning may be necessary as stop rings wear.
Institute ™Introduction 457
Thrust Roller Misalignment
A misaligned thrust roller will result in vertical forces on the roller as shown above.
Roller Tilted to Left Roller Tilted to Right
Roller Offset to Left Roller Offset to Right
Institute ™Introduction 458
Thrust Roller Misalignment
An improperly aligned thrust roller can ride out of its socket, causing damage to tire stop blocks.
Institute ™Introduction 459
Thrust Roller
Thrust rollers can become overloaded if the kiln’s supporting rollers are improperly skewed. This thrust roller base became deformed from excessive force.
Institute ™Introduction 460
Fuller Thrust Roller
Institute ™Introduction 461
Fuller Thrust Roller
Institute ™Introduction 462
Hydraulic Thrust Roller
Institute ™Introduction 463
Hydraulic Thrust Roller
The hydraulic thrust roller maintains a constant, controlled force on the thrust tire and keeps the kiln in an electronically determined position.
Institute ™Introduction 464
Hydraulic Thrust Roller
Guide BarHydraulic Cylinder
Position Sensor
Institute ™Introduction 465
Hydraulic Thrust Roller
Breather
Oil Level Sight Glass
Guide Bar Grease Fittings
The spherical bearings are lubricated with ISO VG 1000 gear oil. Guide bars are grease lubricated.
Institute ™Introduction 466
Thrust Roller
The roller surface is graphite lubricated.
Institute ™Introduction 467
Hydraulic Thrust Roller
Institute ™Introduction 468
Hydraulic Cabinet
The hydraulic power unit is normally placed beneath the kiln’s thrust pier.
Institute ™Introduction 469
Hydraulic Cabinet
Accumulator
Pump
Directional Valve
Relief Valve
Tank
Institute ™Introduction 470
Hydraulic Pump
The axial piston pump has manual adjustments for pressure and flow rate.
Institute ™Introduction 471
Directional Valve
A directional valve directs fluid to the thrust cylinder, or allows the cylinder to bleed down.
Institute ™Introduction 472
Hydro-pneumatic Accumulator
An accumulator stores hydraulic energy. It is used to maintain a steady force on the thrust tire even though the tire wobbles slightly as the kiln turns.
Institute ™Introduction 473
G as Valve
B ladder
Shell
Port
Anti-ExtrusionValve
Nitrogen G as
Fig ure 17.6 Bla d d e r-Typ e Ac c um ula to r
CO PYRIG HT (1999) VICKERS, INCO RPO RATEDC
Hydro-pneumatic Accumulator
The accumulator contains a rubber bladder which is charged with nitrogen gas.
Institute ™Introduction 474
psig0
500
1000
1500
2000
psig0
500
1000
1500
2000
psig0
500
1000
1500
2000
System PressureLess Than p precharge
System Pressureat p m ax
System Pressureat p m in
Fig ure 17.7 Bla d d e r Ac c um ula to r O p e ra tio n
C O PYR IG HT (1999) V IC KER S, INC O R PO R ATEDC
Hydro-pneumatic Accumulator
When hydraulic pressure increases and decreases the gas is compressed and expanded.
Institute ™Introduction 475
Hydro-pneumatic Accumulator
The accumulator is pre-charged with nitrogen to approximately half of the expected average operating hydraulic pressure.
Danger!
Do not charge with air or oxygen!
Institute ™Introduction 476
Pressure Relief Valve
A pressure relief valve limits hydraulic pressure in the system. This prevents excessive downhill kiln force from damaging the thrust roller.
Institute ™Introduction 477
Hydraulic Filter
An in-tank filter with a 10 micron element keeps hydraulic fluid clean. The protruding red button indicates the element needs changing.
Institute ™Introduction 478
Thrust Cylinder LVDT
An LVDT (linear variable differential transformer) mounted in the hydraulic cylinder measures the distance that the cylinder rod is extended.
Institute ™Introduction 479
Thrust System LVDT Cabinet
The LVDT signal goes to a cabinet where the kiln’s hot running axial position is set and where alarms are programmed for excessive uphill and downhill kiln position.
Institute ™Introduction 480
Fuller Hydraulic Thrust Roller
Institute ™Introduction 481
Fuller Hydraulic Thrust Roller
Institute ™Introduction 482
Preventive Maintenance Checklist
Institute ™Introduction 483
Daily• Thrust Roller
• Kilns with one thrust roller (mech. or hyd.)– visual check of the thrust rollers including
recording of the thrust pressure (ideal 500 psi, can vary from 200-800 psi). Maximum design pressure is 1200-1300 psi
– check the temperature of the thrust roller housing and face.
• Kilns with two thrust rollers– Observe the kiln position relative to the uphill or
downhill thrust rollers– Check temperature of the housing and thrust roller
face if there is constant contact.
Institute ™Introduction 484
• Seals
• Visually check feed and discharge seals
• Gear
• Visually check the gear and pinion
• Rollers and Live Rings
• Visually check all roller and tire surfaces
• Lubricate contact faces between tires and shell mounted tire pads and stop blocks using a mixture of graphite powder and water.
Daily
Institute ™Introduction 485
• Temperatures
• Record kiln shell temperatures and include a night visual inspection for “hot spots”
Daily
Institute ™Introduction 486
Weekly
• Check and record direction of thrust on all rollers.• Check lubrication on all support rollers.• Check oil levels in support roller bearings and
thrust roller bearings.• Check and record the tire creep and clearance.• Record related shell and tire temperatures.• Check condition of tire stop blocks and wear rings.
Institute ™Introduction 487
• Check general condition of kiln shell.
• Check contact patterns between gear and pinion by observing the oil smear on the contact face for at least one full kiln rotation.
Weekly
Institute ™Introduction 488
Annually
• Perform complete check of kiln alignment utilizing the laser or mechanical alignment method. Kiln alignments should be completed after major repairs have been made to the kiln.
• With this information recorded and compared, a problem should be caught before a real dilemma occurs (i.e. an unplanned shutdown).
• Prior to planned kiln shutdowns, an extensive mechanical inspection should be completed to determine repairs required.
Institute ™Introduction 489
The Good Old Days
Institute ™Introduction 490
The Good Old Days
Institute ™Introduction 491
The Good Old Days
Institute ™Introduction 492
Rivets
Institute ™Introduction 493
Don’t Be Mean to Your Kiln