Rotary Kiln Maintenance
Rotary Kiln Maintenance
Seminar
Seminar
Kiln Inlet Seal
Kiln Outlet Seal
Thrust Roller
Hydraulic Thrust Roller
Kiln Maintenance Checklist
The Good Old Days
Kiln Miscellaneous
Kiln Inlet Seal
Kiln Inlet Seal
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.
Kiln Pneumatic Inlet Seal
Kiln Pneumatic Inlet Seal
The pneumatic seal consists of two sliding surfaces pushed together by pneumatic cylinders.
Pneumatic Cylinders
Kiln Inlet Seal
Kiln Inlet Seal
Spring Loaded Graphite Plug
Seal Detail
Pneumatic Cylinders
Kiln Inlet Seal Detail
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
Kiln Inlet Seal
Kiln Inlet Seal
The seal is suspended by a carriage which allows it to move longitudinally as the kiln expands and contracts.
Carriage
Pneumatic Inlet Seal
Pneumatic Inlet Seal
The pneumatic cylinders, when pressurized, will press the two seal halves tightly together.
Stationary
Filter, Regulator, Lubricator
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.
Filter, Regulator, Lubricator
Kiln Inlet Seal
Kiln Inlet Seal
The seal’s sliding surfaces are graphite lubricated.
Spring Loaded
Kiln Inlet Castings
Kiln Inlet Castings
Castings on the inlet hood and kiln inlet cone keep the castable refractory in place. Inspect them at annual shutdown.
Spring Plate Inlet Seal
Spring Plate Inlet Seal
Spring Plate Inlet Seal
No, covering the spring plates with plastic won’t help.
Spring Plate Inlet Seal
Outlet Seal
Kiln Outlet Seal
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.
Kiln Outlet Seal
Kiln Outlet Seal
Spring Plate Wire Rope
Kiln Outlet Seal
Kiln Outlet Seal
Counterweight
Spring plates are wrapped with a counterweighted wire rope arrangement to keep them tight against the cowl.
Forced Air Cooling
Kiln Outlet Seal
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.
Kiln Outlet Seal
Kiln Outlet Seal
Kiln Outlet
Kiln Outlet
Seal
Seal
Dust from kiln hood puffing falls down the chutes to the drag chain conveyor or into the clinker cooler.
Kiln Outlet Sector
Kiln Outlet Sector
The kiln nose rings sees severe service and must be regularly inspected for refractory and casting failure.
Kiln Outlet Seal
Kiln Outlet Seal
This alternate spring plates design features outwardly protruding spring plates.
Kiln Outlet Seal
Kiln Outlet Seal
The Most Expensive Seal
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.
Thrust Roller
Thrust Roller Assembly
Thrust Roller Assembly
Oil Seal Oil Level Pipe Spherical Bearings Tie Rod Tire Shims Clearance
Keep the clearance to a minimum (6mm), and adjust the shims to keep the kiln gear in proper longitudinal alignment.
Thrust Roller Assembly
Thrust Roller Assembly
Set Screws
The kiln position can be controlled by adjusting set screws on this thrust roller base.
Thrust Roller Position
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.
Thrust Roller Misalignment
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
Thrust Roller Misalignment
Thrust Roller Misalignment
An improperly aligned thrust roller can ride out of its socket, causing damage to tire stop blocks.
Thrust Roller
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.
Fuller Thrust Roller
Fuller Thrust Roller
Hydraulic Thrust Roller
Hydraulic Thrust Roller
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.
Hydraulic Thrust Roller
Hydraulic Thrust Roller
Guide Bar Hydraulic Cylinder
Position Sensor
Hydraulic Thrust Roller
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.
Thrust Roller
Thrust Roller
Hydraulic Thrust Roller
Hydraulic Cabinet
Hydraulic Cabinet
The hydraulic power unit is normally placed beneath the kiln’s thrust pier.
Hydraulic Cabinet
Hydraulic Cabinet
Accumulator Pump Directional Valve Relief Valve TankHydraulic Pump
Hydraulic Pump
The axial piston pump has manual adjustments for pressure and flow rate.
Directional Valve
Directional Valve
A directional valve directs fluid to the thrust cylinder, or allows the cylinder to bleed down.
Hydro
Hydro
-
-
pneumatic Accumulator
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.
Gas Valve Bladder Shell Port Anti-Extrusion Valve Nitrogen Gas
Hydro
Hydro
-
-
pneumatic Accumulator
pneumatic Accumulator
The accumulator contains a rubber bladder which is charged with nitrogen gas.
psig 0 500 1000 1500 2000 psig 0 500 1000 1500 2000 psig 0 500 1000 1500 2000 System Pressure Less Than pprecharge
System Pressure at pmax
System Pressure at pmin
Hydro
Hydro
-
-
pneumatic Accumulator
pneumatic Accumulator
When hydraulic pressure increases and decreases the gas is compressed and expanded.
Hydro
Hydro
-
-
pneumatic Accumulator
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!
Pressure Relief Valve
Pressure Relief Valve
A pressure relief valve limits hydraulic pressure in the system. This prevents excessive downhill kiln force from damaging the thrust roller.
Hydraulic Filter
Hydraulic Filter
An in-tank filter with a 10 micron element keeps hydraulic fluid clean. The protruding red button indicates the element needs changing.
Thrust Cylinder LVDT
Thrust Cylinder LVDT
An LVDT (linear variable differential transformer) mounted in the hydraulic cylinder measures the distance that the cylinder rod is extended.
Thrust System LVDT Cabinet
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.
Fuller Hydraulic Thrust Roller
Fuller Hydraulic Thrust Roller
Preventive Maintenance Checklist
Daily
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
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
Temperatures
• Record kiln shell temperatures and
include a night visual inspection for “hot spots”
Daily
Weekly
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.
•
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
Annually
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.