Rotary Vessel Alignment

• For a rotary vessel to perform at optimal mechanical capacity it is essential for the vessel to be aligned correctly.
• To obtain extended life from rotary vessel refractory it is essential for the vessel to be aligned correctly.
• To maintain rotary vessel maintenance costs at a manageable level it is essential for the vessel to be aligned correctly.
• To obtain extended life and reduce wear on running components it is essential for the vessel to be aligned correctly.
• To minimise the likelihood of shell failure it is essential for the vessel to be aligned correctly.

What is Rotary Vessel Alignment?

Rotary vessel alignment is achieved only when the vessel’s running components are centred on a common axis, both horizontally and vertically, and in proper co-incidence with the drive-train.

How is Rotary Vessel Alignment achieved?

To achieve rotary vessel alignment it is first necessary to know where the actual centreline is in relation to the theoretical or design centreline.
The only way to establish this relationship is to carry out an alignment survey, preferably with the vessel in full production mode excepting for Ball Mills.
After the alignment survey is completed and analysed, manipulation of trunnion rollers can be carried out to correct identified alignment errors.

Survey Procedure

Almost all problems associated with rotary vessels can be attributed to misalignment.

Although the current trend is towards 'soft' non-contact measurements taken from areas outside the hot air envelope along the vessel, there are inherent problems associated with this technique, such as:

• Temperature front refraction
• Variable light conditions
• Oblique angles
• Unbalanced geometric networks
• Limitations of electronics in harsh environments

Some of these factors are not quantifiable and their impact may vary from one day to the next.
Other factors do not even allow proper closing out of the survey in accordance with good surveying practices.
We believe too much unquestioned acceptance of digital read-outs has lead to many of the problems we have been commissioned to rectify.

These problems led Australian Kiln & Mill Services Pty. Ltd. to revert to the basic, more direct (albeit less comfortable) approach by working entirely within the hot air envelope with 'hard' contact measurements to the various critical components as required for evaluation of alignment status. ‘DIRECT METHODS ARE BEST METHODS’.

The Australian Kiln & Mill Services Pty. Ltd. alignment procedure enables determination of ‘X’, ‘Y’ and ‘Z’ co-ordinates of the running centres (tyres and rollers), the only places alignment adjustments can be made. From this information the alignment status of the vessel can be identified.

The following should be considered:

• Some measurements are more critical than others. For example, measurements between stations need not be as precise as those taken around each station.
• Correct alignment of running centres and surfaces enhance equipment availability and refractory life.
• There is a tendency to finesse alignments when there are too many uncontrollable and unpredictable influences which affect vessel behaviour on an irregular basis. For example, water table, weather, refractory condition, vessel live load, flame focus and shell hot spots.
• A regular and practical rotary vessel alignment is the best maintenance tool.

An Australian Kiln & Mill Pty. Ltd. alignment package will result in information relating to:

• Current vessel alignment status
• Condition of the tyres and trunnion rollers including tyre chairs and tyre stops
• Tyre and trunnion roller running face profiles
• Trunnion roller inclinations
• Condition of the girth gear and pinion running faces
• Girth gear run-out and meshing status
• Trunnion roller bedplate inclination, orientation and condition
• Actual vessel inclination

All of the above information is supplied, along with alignment adjustment recommendations, on a series of drawings which can be supplied in either hard copy or electronically. Included in the package is a comprehensive mechanical condition report with recommendations for the repair or improvement of the relevant plant items.

Australian Kiln and Mill Services Pty. Ltd. offers an ‘on-the-run’ rotary vessel tyre and trunnion roller machining service. Worn or damaged tyre and roller running faces are machined flat and parallel while the vessel is in operation resulting in zero loss of production during the process. Australian Kiln and Mill Services Pty. Ltd. use a single tip cutting tool machining rig for this work.

Reconditioning

Australian Kiln & Mill Services offers an 'on line' tyre and trunnion roller surface reconditioning service. That is, worn or damaged running faces of tyres and rollers can be machined flat and parallel while the vessel is in operation.

The Machining Process

• To machine a tyre, the machining rig is set to the vessel inclination and the ceramic tipped cutting tool is set at the horizontal tangent height of the tyre by means of adjustable support legs. Using guide rollers, the cutting head is forced to follow the tyre. This 'floating' arrangement allows achievement of a flat finish regardless of tyre movement. A parallel surface of within 0.5mm on the diameter is generally achievable with this method. Tool feed rate is controlled by a variable speed drive which can be set to obtain the desired surface finish.


• To machine trunnion rollers, the machining rig is mounted directly onto the bedplate. Should this not be possible then the machining rig can be mounted onto a temporary structure welded to the bedplate. The machining rig is set parallel to the trunnion roller centreline and the cutting tool is set at the horizontal tangent height of the trunnion roller. The tool feed rate is controlled by a variable speed drive which can be set to achieve the desired surface finish. A parallel surface of within 0.2mm on the diameter can be achieved in this way.


• During the machining process the vessel axial thrust characteristics will change. The machining crew monitor vessel reactions and make compensatory adjustments to trunnions to maintain equilibrium of the vessel.


• After completion of the machining process the finished diameter of the tyre or trunnion roller is measured using an electronic diameter-measuring device and trunnion roller settings are calculated to compensate for the reduced diameters. The vessel is left in a balanced state of axial thrust, although it is normal procedure for the vessel to require further tuning adjustments as the running faces 'polish-up'. These tuning adjustments are normally carried out 8-10 days after completion of the machining process.

Australian Kiln & Mill Services provides a full 'on line' tyre and trunnion roller reconditioning package. Our experienced technicians carry out the service with no input required from the client. Tyre and trunnion roller diameters are measured before and after reconditioning to ensure a flat and taper free result is achieved with removal of a minimum amount of metal. The rotary vessel will be left in a balanced state on completion of this reconditioning process.

Maintenance & Inspection Programmes

Our maintenance inspection programme has been designed to help clients adopt a proactive approach to rotary vessel maintenance.

Direct benefits of the programme include:

• Compilation of a comprehensive history of wear rates for mechanical components
• Unplanned stoppages will be reduced
• Achievement of maximum plant availability becomes a realistic goal thereby increasing production and reducing operating costs
• Reduced wear rates achieved due to vessels being correctly aligned and tuned on a regular basis rather than on an 'as needed' basis
• Efficient planning for programmed shutdowns
• Confident budget planning for replacement of high cost items such as girth gears, pinions, tyres and trunnion rollers

Installation & Repair

Australian Kiln and Mill Services Pty. Ltd. offers a full rotary vessel repair service. Our personnel are experienced in all aspects of major repairs on any size rotary vessel. Our expertise includes the following:

• Installation of new rotary vessels
• Replacement of shell sections
• Replacement of tyres, tyre chairs and tyre stops
• Replacement of trunnion rollers
• Reconditioning of trunnion roller bearings - hand scraping
• Re-setting of bedplates – replacement or in-situ machining
• Replacement of girth gears and pinions
• Refurbishment of girth gears and pinions in-situ
• Re-centring of girth gear – flange mounted or tangent plate mounted
• Straightening of shells by cutting and re-welding
• Reconditioning of tyres and trunnion roller running faces - ‘on-the run’
• Alignment and adjustments of trunnion rollers
• Tracking/tuning/training of vessel

Australian Kiln and Mill Services Pty. Ltd. has the personnel, experience, capability and expertise to programme, schedule and complete a project on a ‘turn-key’ basis.