Rotary Kiln MaintenanceSeminar Kiln Shell Kiln Shell Shell Details Kiln Crank Measuring Kiln Crank Heat Correction of Kiln Crank Shell Repair Shell Welding Submerged Arc Welding Shell Details Outlet Shroud 50 mm 75 mm (under tire) . 2 40 mm (gear) 40 mm 75 mm (under tire) 30 mm 40 mm 30 mm 80 mm (under tire) 40 mm Typical shell plate thicknesses. 1 Tire No.Shell Details Inlet Cone 30 mm Tire No. 3 Tire No. Kiln Crank . cyclical loads and stresses occur in the shell and the kiln supports. .Kiln Crank Kiln crank occurs when a kiln shell is not perfectly straight. As the shell turns. leading to shell cracks and fatigue cracks in the roller shafts.Kiln Crank Kiln crank can cause severe cyclical loads. . .Kiln Crank Kiln crank will result in gear misalignment which can destroy gear teeth. as in the case of a shell damaged by heat blisters. . as in the case of a rain warped shell. or permanent.Kiln Crank Kiln crank can be temporary. one side of the shell cools off and contracts. causing a concave up curvature.Kiln Crank When a hot kiln is stopped during a heavy rainstorm. . 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. . 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. . Kiln Crank Damaged refractory will cause a hot spot in the shell. . . Refractory bricks will no longer stay in place and the shell section will have to be replaced at great expense.Kiln Crank A hot spot left unattended will wrinkle the shell and create a crank. causing tires to run off-center. .Heat Damaged Kiln Shell A heat-wrinkled kiln shell will also shorten the kiln. .Kiln Crank Kiln crank can be caused by poor alignment of kiln sections during assembly or repair. Kiln Crank Kiln crank can be caused by weld shrinkage at a temporary shell patch. . Measuring Kiln Crank . 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. . 3 mm typically indicates a crank in the shell that should be repaired. .Measuring Kiln Crank A roller that deflects cyclically with kiln rotation by over 0. A polar diagram is generated on which the deviation from the true kiln center can be seen.Measuring Kiln Crank Kiln crank can be measured by measuring shell runout. . .Measuring Kiln Crank A series of polar diagrams gives a picture of the shell crank. Heat Correction of Kiln Crank . Heat Correction of Kiln Crank A kiln shell can sometimes be straightened by heat correction. Shell stresses then diminish as the kiln sags into place on the rollers. . allowing the shell steel to overheat. Insulation is wrapped around the shell. Heat Correction of Kiln Crank Temperature sensors are installed to carefully monitor shell temperatures beneath the insulation during the correction process. . Heat Correction of Kiln Crank . Shell Repair . . The bandaid approach is at best a temporary solution.Shell Repair Major shell defects are normally repaired by replacing the damaged section. Field Joint Hardware New shell sections are joined with adjustable erection lugs. . Shell Alignment By adjusting the erection lugs the shell sections are straightened until a perfect centerline is achieved. . Tire Handling . Shell Rigging . Shell Rigging . Shell Handling . Spider Bracing . Spider Bracing . Spider Bracing . These rings would eventually cause shell cracks due to heat expansion. .Shell Stiffening Rings Many older kilns had shell stiffening rings. Field-cutting expansion slots may help this problem. Shell Welding . .Joint Preparation Prior to welding the shell plate ends are carefully prepared. Weld Shrinkage The 60º double V weld results in less shrinkage and less weld metal being required. avoiding the “gull-wing” effect. Weld distortion is minimized. . Weld Shrinkage . Shell Welding . .Shell Welding After completing the outside weld. the root pass is removed using carbon arc gouging. .Shell Welding After gouging. the joint is carefully cleaned and inspected to ensure that no defects from the root pass remain. the joint is inspected radiography or ultrasound. Defects are marked and then repaired. .Shell Welding When welding is finished. Submerged Arc Welding . Submerged Arc Welding Submerged Arc Welding Submerged Arc Welding Submerged Arc Welding The depth of penetration increases with increased current. The depth of penetration is also dependant of the welding speed. . Submerged Arc Welding • The depth of penetration is high with the welding rod as PLUS POLE and law with the welding rod as MINUS POLE. . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding . Submerged Arc Welding .