7.Kiln Alignment

Rotary Kiln Maintenance Seminar

Kiln Alignment

Kiln Alignment

Alignment Principles Internal Alignment Hot Kiln Alignment

Alignment Principles

Kiln Alignment

A kiln is considered aligned when the center of rotation of the kiln shell at every support lies on a straight line.

Kiln Alignment

Two Support Kiln Note that a kiln with only two supports is always aligned, as there is always a straight line between two points.

Kiln Alignment

Horizontal Axis

Vertical Axis

A kiln can be misaligned in the horizontal or in the vertical plane.

Consequences of Misalignment 3902 kN

3597 kN

6491 kN

3067 kN

7048 kN

2815 kN

10 mm

Misalignment changes the loading on the kiln supports and causes overstressing of the shell and supports.

Consequences of Misalignment

Misalignment can result in all of the load being concentrated on one roller.

Internal Alignment

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.

Internal Alignment

New kiln sections usually have steel spider bracing with precisely marked centers. If not, wooden batter boards can be prepared.

Internal Alignment

The kiln shell’s center is found by scribing four arcs on a target card tacked onto the batter board.

Internal Alignment

Drawing diagonals at the arcs’ intersections will locate the center.

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.

Kiln Alignment Top Clearance Tire centre

S Kiln centre

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.

Correcting Misalignment

Roller Adjustment

Field Joint Adjustment

After measurements are taken the kiln is aligned by adjusting rollers and field joints.

Correcting Misalignment

h

h

h

Moving both rollers horizontally will move the kiln center by the same amount.

Correcting Misalignment

C

A

B

C

B

A2 + B2 = C2 Roller adjustments to correct vertical alignment can be calculated from the relationship of right triangles.

Correcting Misalignment

¼ ½

1

Moving one roller horizontally will move the kiln center horizontally by half and vertically by one quarter (approximately) of the distance.

Correcting Misalignment

Caution! Moving a roller on the piers immediately uphill and downhill from the kiln gear will affect the gear alignment.

Hot Kiln Alignment

Hot Kiln Alignment Advantages 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.

Hot Kiln Alignment

Mechanical Hot Kiln Survey Method Laser Kiln Survey (LKS) Method

Hot Kiln Alignment Both methods utilize a variety of measured data to determine kilns axis: 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.

Mechanical Alignment

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 Λ

Tire centre

s Kiln centre

a

b

dleft

dright c q cleft

f

F

j cright

Using an optical level the elevations of the bearing base frames are determined.

Mechanical Alignment

Elevation Markers

Elevation markers on kiln piers should be checked to see if a kiln pier has sunk.

Roller and Tire Circumference

Using a precision measuring wheel and tachometer the circumference of the roller and tire are measured.

Roller and Tire Circumference Magnet

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.

Mechanical Alignment

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

Λ s dleft

a

b

c q cleft

cright

drightf j

F

Laser Kiln Survey

Tire elevation and location can be determined utilizing a laser theodolite from ground level.

Laser Kiln Survey Kiln Center Tolerances Horizontal Plane

± 1.5 mm

Vertical Plane

± 2.5 mm

Laser measurement provides the most accurate method of kiln alignment.

Laser Kiln Survey

Laser Kiln Survey

Laser Kiln Survey

Laser Kiln Survey