polysius® Rotary KilnBuilt to run. Serviced to last.

There are basically two different systems that can be used to fasten kiln tyres to a kiln shell: the splined or the loose tyre fastening system. The splined system transfers the load from the rotary kiln shell into the kiln tyre by means of a form-fit connection, ensuring that the kiln shell is kept as round as possible. It consists of floating tyre pads held by axial and radial stops welded to the kiln shell, plus a wedge tensioning system. The teeth of the tyre are pressed against the tyre pads and the radial stops by the wedge tensioning system; the force runs from the radial stop through the tyre pads into the tyre tooth and the tyre itself. The greatest load during operation is at the three and nine o'clock positions. The system allows unimpeded expansion of the shell as operating temperatures increase, so the shell remains round under all operating conditions and constriction is prevented.

SERVICE ADVANTAGES

• Lower operational ovality of the tyre-bearing shell section and lower dynamic stress on the refractory lining

• Prevention of any refractory lining bricks falling out and higher stability of the clinker coating

• Lower operating costs — tyre clearance requires no correction and no lubrication

The loose system transfers the load by means of floating tyre pads and essentially consists of tyre pads, shim plates, radial and axial stops and the lateral limit rings. The shim plate floats on the kiln shell and is secured by the axial stops welded to it; compensation plates can be inserted under the tyre pads for fine adjustment of the tyre clearance. The axial limiters absorb the axial force resulting from shell expansion, skewing of the supporting rollers and the action of the axial thrust system. Because the outside diameter of the fastening system is smaller than the inside diameter of the tyre, they do not migrate the same distance circumferentially — the resulting slippage, measured in mm per kiln rotation, provides key indications of the condition of the shell and the fastening system.

SERVICE ADVANTAGES

• Protection of refractory lining from excessive ovality

• Easy replacement of both tyre pads and shim plates, which makes the radial tyre clearance easy to adjust and the ovality controllable by means of tyre pads

• Cost-effective system, proven over decades

• Low welding stresses of axial and radial stops

For rotary kilns and drums subjected to very high temperatures, tyre fastening systems providing a suitable clearance are used, as the radial thermal expansion of the shell is greater than that of the tyre. For rotary kilns and drums operated at low temperatures, however, the thermal expansions are so low that the tyre can be permanently joined to the shell. The welded-in tyre consists of a massive forged body with a rectangular cross-section that transitions on both sides into conical flanges, which facilitate the connection to the adjacent kiln shell sections. A significant advantage is that this connection requires no inspection or maintenance work, and the firm material bond results in low ovality of the shell section in this area — with a positive effect on refractory lining service life.

SERVICE ADVANTAGES

• Low ovality leads to higher availability and a longer service life

• Lubrication or maintenance of the fastening system is not required

• Cost-effective system

• A forged type has a homogeneous material structure, is free from cavities and shows no defects

• Static re-calculation provided that the required information is available, regardless of the manufacturer

The vertical and horizontal forces caused by the supported load must be absorbed by the foundations via the supporting rollers. The supporting roller unit consists of the supporting roller, non-detachably connected to the supporting roller axle. A distinction is made between the supporting rollers of a multi-support kiln, which only act as supports, and those of a two-support kiln, which are directly driven for the friction drive. Diameter is selected to ensure safe continuous operation without exceeding the permissible contact pressure per unit area with a correctly aligned rotary kiln; the yardstick for service life is the number of load cycles. Supporting rollers are generally wider than the corresponding tyres in order to utilise the entire tyre width for power transmission during the axial movement of the rotary kiln. The main load is the shearing in the axle caused by the supported load. polysius® supporting rollers are exclusively forged in order to achieve maximum quality and operational reliability.

SERVICE ADVANTAGES

• Continuous production and quality monitoring

• Advantages of forged supporting rollers: homogeneous material structure, no cavities or defects, reject-free production

• Static recalculation with corresponding information, manufacturer-independent

• Design and manufacture according to the latest standard

• Quotations for repair or refurbishment of used supporting rollers in one of our worldwide service workshops

Retrofit note: In the event of a fault, the supporting roller can be refurbished in one of our workshops and fitted with a new axle, with due consideration to the number of load cycles.

polysius® supporting roller bearings are plain bearings. As standard, lubrication of the bearing trunnions takes place by means of a rotating oil scooping system mounted at the thrust disc; the circulating lubrication system supplements this to ensure sufficient lubrication at low speeds. Cooling is carried out primarily using cooling water conveyed through the cooling-water chambers in the bearing base. Where the rotary kiln is operated in locations with extreme annual temperature differences or very high ambient temperatures, a plate-type heat exchanger on an oil/water basis can be added; at extremely low ambient temperatures a heating system is added so that lubricant viscosity allows optimal lubricity at any time. In the case of imminent overheating, the cooling system can also be activated to increase the interaction window for stopping the cause, thereby decimating the number of unplanned stoppages. The system is an all-in-one compact solution providing heater, cooler and — at the customer's request — filter as a complete unit.

SERVICE ADVANTAGES

• Protection against insufficient lubrication

• Temperature control — protection against hot bearings

• When used with filter: screening-out of abraded material and solid matter

• Increased service life of the bearing shells

• Applicable to all makes

• Compact size with low space requirement

Increasing demands on quality and delivery time, and above all size, are increasingly limiting manufacturing options. polysius® girth gears are available as welded constructions or milled from solid forged material, the latter being the most rugged construction available on the market. The welded girth gear is composed of the web plus upper and lower flange; all blanks are solid forged, the flanges are welded to the web by means of a full penetration weld so that maximum strength and load distribution are achieved, and heat treatment and gear tooth forming follow — a design proven since the 1990s. The girth gear milled from solid metal has the same design; as it is machined from a solid forged blank it requires no additional heat treatment other than hardening and tempering, and geometric deviations are reduced to a minimum as the component is free of welding stresses.

SERVICE ADVANTAGES

• Homogenous structure

• No rejected blanks due to casting defects during production

• Can be retrofitted to any rotary kiln

• Compatible with the bridge plate fastening system: heat shield protects against thermal stress, easy to turn, can be aligned quickly and accurately

• Very rigid in circumferential direction — torque is transmitted without the girth gear buckling

Retrofit note: Can be retrofitted to any rotary kiln.

The girth gear and pinion drive transmits the torques generated by the drive into the rotary kiln in order to set it in continuous rotary motion. The fastening system connects the girth gear to the kiln shell, either by means of a tangential plate construction or via a bridge plate construction. With the bridge-plate construction, so-called bridges are welded to the shell and bolted to the girth gear; the system resiliently absorbs the axial and radial expansion differences between shell and girth gear and fixes the girth gear relative to the rotary kiln. The system includes in-built thermal protection — single or double, depending on the clearance between shell and girth gear — protecting the girth gear from excessive heat radiation. The periphery deserves particular consideration with the use of secondary fuels and higher process temperatures, or with regard to shifting of the clinkering zone. The tangential connection, on the other hand, is a cost-effective solution for rotary dryers with low thermal loads and smaller nominal diameters.

SERVICE ADVANTAGES

• High rigidity in circumferential direction for transmission of the driving forces

• Optimum introduction of the driving forces into the kiln shell

• High flexibility in radial direction to compensate for ovality and thermal expansion of the kiln shell

• Realignment / turning of the gear rim possible at any time due to the symmetrical and low-wear attachment

• Thermal protection against heat radiation between kiln shell and girth gear leads to hardly any gaping of the joints

• Prevents jolting when the girth gear joints roll over the pinion and prevents wear

The optimum load on the girth gear and pinion is achieved by means of a swivelling baseplate with a guided self-aligning pinion. This mechanism compensates for operationally related meshing interference between pinion and girth gear at all times; the optimum contact ratio thus maintained means that much smaller tooth sizes than before can be used, due to the lower point load. The pinion unit consists of the pinion shaft, the spherical plain bearings and the self-aligning pinion. The spherical bearings allow flexible mounting of the shaft, and the self-aligning pinion compensates for the wobbling that occurs during operation, ensuring that the tooth flanks make contact uniformly across their entire width. The baseplate is designed so that the pinion always follows the radial movement of the girth gear, and both are equipped with two guide rings to keep radial and axial backlash the same. With polguide it is possible to build two-support rotary kilns with greater length/diameter ratios than with the classic girth gear/pinion concept; on multi-station kilns it significantly lengthens the service life of girth gear and pinion.

SERVICE ADVANTAGES

• Optimal tooth gearing under all operating conditions at all times

• Compensation for radial movements (radial runout), angle changes (axial runout) and axial movement (expansion)

• Low wear

• Double-pinion operation possible

• Can be used for rotary kilns of all sizes

The girth gear and pinion drive requires continuous lubrication to protect the tooth flanks — the surfaces subjected to the highest Hertzian load — from premature wear. With optimal lubrication and maintenance of the system, pitting of the tooth flanks can be avoided. The system is basically a sump filled with lubricant underneath the girth gear and pinion drive; the pinion teeth dip into this bath so that the contact surface is continuously lubricated. In addition, lubricant from the bottom of the sump is drawn by a circulation pump and fed across the entire width of the inward-turning side of the pinion by means of a pipe system — the highly viscous fluids flow off and do not result in material build-up as with a spray lubricating device. The bath is thoroughly mixed and evenly heated through the rotation of the pinion and the circulation pump. At the lowest point of the sump there is a collecting cup with an oil drain pipe and a dewatering line; lubricant level can be monitored via a sight glass or centrally via a filling level monitor at the control desk. If necessary, an oil heating system ensures optimum viscosity at low ambient temperatures.

SERVICE ADVANTAGES

• Protection against increased wear

• Maximum operational reliability

• Can be retrofitted to any rotary kiln, provided that it has a girth gear and pinion drive and a foundation drawing is available

• Centrally monitored filling level by means of a filling level monitor

• Wear-free system

• Lubricant change requires only a short amount of time

Retrofit note: Requires a girth gear and pinion drive and a foundation drawing.

The protection cover performs a number of elementary tasks contributing to the long-life, flawless operation of girth gear and pinion drive. Its main function is to protect the otherwise open girth gear and pinion drive from external environmental factors such as exposure to dust and the elements; in addition it prevents the escape of environmentally harmful oil or grease emissions arising from lubrication. The cover generously seals girth gear and pinion drive from the environment via a wear-free labyrinth seal, and at the same time forms a drain channel for dripping oil or heated grease, directing it into the collecting vessel. It is available in two versions: in combination with a spray lubricating device, or as a splash lubrication system — the latter is standard in new installations due to the operational reliability of the lubricant supply.

SERVICE ADVANTAGES

• No abrasive wear due to any kind of dust getting in

• Can be retrofitted to any rotary kiln, provided that it has a girth gear and pinion drive and a foundation drawing is available

• No wear-prone sealing elements are used

• Compatible with both bridge plate fastening systems and tangential plate fastening systems

• Maintenance free

• Protects man and environment

Retrofit note: Requires a girth gear and pinion drive and a foundation drawing.

The hydraulic axial thrust system is arranged downhill relative to the tyre and counteracts the downhill force of the inclined rotary kiln, moving it uphill and downhill in axial direction. The movement prevents the tyres from wearing into the supporting rollers. The system forces the rotary kiln to move axially by ±15 mm at adjustable time intervals. Depending on kiln size, tyre geometry and downhill force, either only a short-stroke thruster or a combination of short- and long-stroke thruster is used: the short-stroke thruster sits at the inlet-end roller station and is coupled with a limiting thruster; the long-stroke thruster at the middle roller station supports it and, before start-up, is set to the calculated longitudinal expansion. The scope of supply also includes a hydraulics cabinet with proximity sensors mounted on the system — the travel path is defined via the proximity switches, which switch the high-pressure pump on and off or actuate the control valve opening the return line to the oil tank. The limiting thruster on the uphill side of the tyre limits any unintentional kiln movement towards the inlet housing; in normal operation it has no function, but if the limiting roller is set into rotary motion by the tyre it causes the high-pressure pump to switch off immediately.

SERVICE ADVANTAGES

• Uniform uphill and downhill movement of the rotary kiln

• Uniform contact pattern of supporting rollers and pinions

• Can be retrofitted to any rotary kiln

• Low axial load on the supporting roller bearings

• Limits uncontrolled upward movement of the rotary kiln

• Prevents damage to the inlet housing

Retrofit note: Can be retrofitted to any rotary kiln.

Inlet and outlet graphite seals separate the kiln process from the environment, sealing it off from leak air while ensuring maximum process reliability and availability. No additional modifications of the rotary kiln are necessary to retrofit the polysius® graphite seals — independent of the kiln manufacturer. The graphite seal is the connecting link between rotating and stationary components; sealing against rotating and axial movement is achieved by graphite blocks distributed around the circumference. When the rotary kiln moves axially, the blocks slide on the slide ring; when it moves radially or wobbles, the tensioning ropes with counter weights press the blocks onto the slide ring. Two separate tensioning ropes for the upper and lower strand ensure easy and uniform pretensioning by steel weights. The air-cooled sealing casing minimises thermal effects on the graphite blocks. The fastening system on the inlet and outlet side enables the compensation of age-related wear, independent of the kiln manufacturer; the tangential support on the outlet side facilitates assembly if kiln shells are deformed. Powdered material that gets into the seal area is discharged via a dust chute.

SERVICE ADVANTAGES

• Improves the stability of the clinker production process

• High availability

• Low installation and maintenance costs

• Easy installation and short assembly time

• Rapid amortization

• Energy saving by reducing false air

• Reduces CO2 emission

Retrofit note: No modifications of the rotary kiln necessary — independent of the kiln manufacturer.

The pneumatic inlet and outlet seals isolate the kiln process from the environment, sealing against false air. They withstand high radial and axial movements of the rotary kiln exceptionally well, especially in two-station kilns, and the low-wear design ensures a long service life. The seal connects the rotating kiln shell with either the stationary inlet or outlet housing; the sealing ring is gimbaled to the housing by means of the seal suspension and supports the pneumatic cylinders. Rotational movement: the wear rings are pressed against each other by the pneumatic cylinders to provide the sealing function even if the rotary kiln wobbles, with an integral graphite lubrication device optimizing the friction coefficient between the fixed and the floating wear ring. Axial movement: the sealing function is performed by the sealing cord fed through the sealing ring and pulled tautly around the non-rotating ring; during axial movement, the cord migrates circumferentially around the non-rotating slip ring.

SERVICE ADVANTAGES

• Less false air in the process, which leads to stabilization of the clinker production process, energy saving and lower CO2 emissions

• Separate sealing for axial and radial movement

• Sealing function is provided even in the event of eccentricity of the rotary kiln inlet

• Uniform contact pressure by pneumatic cylinder on axial expansion of the kiln shell

• Easy maintenance due to dual-circuit pneumatic system

The protective segment at the kiln outlet separates the kiln process from the surrounding; the aim is to provide a seal against false air with the highest process reliability and availability. It forms the end of the refractory lining at the outlet, and due to the slope of the end edge the refractory bricks are held in position. Thanks to the improved design, the new segment is located below the refractory lining, which means clinker discharged from the rotary kiln no longer comes into contact with it — abrasive wear at the segment is avoided and heat input reduced. The optimised and patented cooling concept significantly reduces the temperatures in the segment, resulting in a decrease in oxidation wear and a significant increase in material strength in the highly thermally loaded area. The new segment achieves a longer service life at an attractive price.

SERVICE ADVANTAGES

• Significant decrease in oxidation wear

• Increase in material strength

• Refractory bricks serve as wear protection and can be replaced without removal of the segments

• In the case of thyssenkrupp rotary kilns, the new protective segment can be used to replace the original component

• Rapid amortisation

Retrofit note: In the case of thyssenkrupp rotary kilns, retrofittable without modifications.

Fundamentally, the cyclone stage of a preheater fulfils two functions: heating of the raw meal in the gas stream, and collection and discharge of the raw meal via the meal chute. The dip pipe is suspended at the upper end of the cylindrical outlet of the cyclone; it stabilises the vortex, increases collection efficiency and reduces dust return. The design depends on the installation location and the heat load: dip pipes are available made of rolled, heat-resistant sheet metal and of high-alloyed cast stainless steel. In the upper cyclone stages, segmented dip pipes of rolled sheet metal are used up to a maximum thermal load of 650 °C and are bolted together for optimal stability. At a higher thermal load above 900 °C, as in the lower cyclone stages, dip pipes made of cast segments are used, where stability is achieved via a meshing hook system; a final dip pipe end ring at the lower end ensures constant roundness. If a dip pipe is worn out or has even fallen off, collection efficiency drops enormously — the consequences are a higher exhaust gas temperature and correspondingly higher energy consumption.

SERVICE ADVANTAGES

• Available in any diameter and length

• Stiffening ribs to counter creep effect

• Maximum stability thanks to elements that hook into each other

• Stabilising ring for constant roundness

• Retrofittable to any cyclone, provided that a drawing of the cyclone cover is available

• Available ex stock at short notice

• High-alloyed stainless steel material

Retrofit note: Retrofittable to any cyclone, provided a drawing of the cyclone cover is available.

The tertiary air duct conveys oxygen-rich tertiary air from the clinker cooler to the calciner in order to boost optimum combustion of the fuel supplied; for the adjustment of the air distribution, dampers have to be installed in the duct. In horizontal piping sections, tertiary air dampers are often used for this purpose — but they characteristically require very much space and frequently jam due to being linearly guided in a baffle. The special design of the new polysius® damper type prevents jamming to a great extent and makes it particularly suitable for horizontal piping sections. To ensure a long service life at low maintenance costs, a special wear concept has been applied; moreover the new damper type has been thermally optimised such that no active cooling is required.

SERVICE ADVANTAGES

• Significantly less space required in comparison with traditional tertiary air dampers

• Less abrasive wear thanks to optimised design and improved wear concept

• Low maintenance requirement

• The optimised design of the damper's base reduces the setting forces, which minimises the risk of jamming

• The actuator of the damper can be suited to the customer's requirements

• Quick return on investment