Works trials split bearings
Maintenance time and cost has been reduced by a new approach to bearings in a Wessex Water treatment plant, says Adrian Menzies of Revolvo
An initial trial of four split roller bearings (SRB) units has been undertaken at a Wessex Water wastewater treatment works. Wessex Water operates wastewater and water networks throughout South-west England.
Several of the company’s wastewater sites incorporate orbital aeration tanks as part of the sewage treatment process. Each of these tanks has a number of horizontal rotors which agitate the sewage and introduce oxygen, thereby accelerating the treatment process.
In the past, the rotors have always been supported by two solid bearings with internal seals. However, this arrangement has not proved ideal. During periods of heavy rain it is possible for the sludge level in the aerator tanks to rise to the point where the bearing units become temporarily submerged, compromising the bearing seals and leading to premature bearing failure.
Replacement presents its own set of problems. In order to change out the solid bearings, each rotor must be lifted clear of the tank. Furthermore, depending on the level of corrosion, the rotor may then have to be completely removed for workshop based remedial work. In either case, the most substantial part of the cost is crane hire, which can be in excess of £2,500 per day.
Revolvo undertook a full evaluation of the existing application conditions and proposed a solution based upon its SRB range. The split bearing units were specified with housings and supports designed to be interchangeable with the existing bearing units wherever possible, or incorporate adaptor plates if necessary.
The trial period was undertaken throughout the winter months and contained several periods of heavy rainfall, subjecting the SRB to a number of high water level situations. Despite this, the bearings performed to expectations and continue to run smoothly and reliably.
The split-to-the-shaft design and advanced sealing of Revolvo’s SRB allow easy maintenance without having to remove the shafts of long horizontal rotors that agitate sewage and introduce oxygen to the treatment process. In addition, the sealed SRBs are designed to withstand full submersion in sewage sludge, which can occur due to raised levels in the aerator tanks during periods of heavy rainfall.
The housings were also equipped with high performance split rubber lip seals with garter springs and retaining plates, to guard against water ingress during intermittent submersion. Finally, and importantly, the bearings were equipped with remote grease points that allow maintenance without engineers ever having to come into contact with the sludge.
The use of SRB bearings promises large future cost savings for Wessex Water. Should the need arise in future to change a SRB split bearing, it will only be necessary to support the rotor shaft, eliminating the necessity and cost of crane hire. This in itself will easily recover the investment of using the SRB split bearing units.
- Top tips for... analyser maintenance Keeping continuous water analysers well maintained is vital to ensure you can rely on the information they provide, writes... Read More >
- Water companies track down private pumping stations Water and sewerage companies in England and Wales face a deadline of 1st October 2016 for adopting most private pumping... Read More >
- Project Focus: All change for vital Severn Tunnel pumping system An upgrade which saw two screw pumps replaced by four rotary lobe pumps has helped protect a crucial National Grid power... Read More >
- Gasification of Sludge: Innovation in Action Yorkshire Water's advanced thermal conversion (ATC) gasification plant at Lower Brighouse WWTW has achieved a timely... Read More >
- Water Industry Awards 2018: Enter Now! The Water Industry Awards, organised by WWT and WET News, are back for the 12th successive year and are now open for... Read More >
- Thinking outside the box on alternative water Water companies' response to a short-term supply disruption is often to distribute bottled water, but Thames Water is now... Read More >
- New Sludge Conference to be part of Wastewater 2018 The UK's largest wastewater event - Wastewater 2018, organised by WWT - is set to return to Birmingham on 30th January and... Read More >
- Comment: Moving sensors from the lab to the real world Innovative sensor technologies of various materials are out there - the key now is to apply them effectively and to make... Read More >
- Head of Tendering & Design Salary Range: Commensurate with roleThe Tendering & Design Department plays a critical role in turning customer enquiries in to fully costed... Read more here.
- Head of Operations Salary Range: Commensurate with role Head of Operations: The Head of Operations will be responsible for the successful day to day delivery... Read more here.
- Waste Water Network Manager c. £42,000 depending on skills and experience An exciting opportunity has arisen for the role of Wastewater Network Manager within the Asset... Read more here.
- Deputy Directors – multiple roles The Office of Rail and Road (ORR) is the independent economic and safety regulator for Britain’s railways, overseeing an industry that carried... Read more here.