Feature Waste management & recycling
Wear protection facilitates sludge-to-energy process
Sewage sludge from wastewater has long been viewed as an expensive nuisance. However, new regulations preventing dumping at sea or in landfill have resulted in Utilities increasingly turning to technologies to help extract energy and other valuable products from wastewater sludge. This development makes sound economic as well as environmental sense but there is a need for wear protection such as that supplied by Kingfisher Industrial Motion to protect pipework
ewage contains 10 times the amount of energy needed to treat it; and it is technically feasible to recover energy from sludge. As a renewable energy source, it can be used directly in wastewater treatment, reducing a facility’s dependency on conventional electricity. Or as a fossil fuel substitute supplying the power utility, cement and mineral processing industries with a secondary fuel source in lieu of coal, to reduce emis- sions of greenhouse gases.
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Using solids as a resource may help stressed public budgets, however, as with any energy-from-waste (EFW) operation, there are costs involved. Wastewater solids must be processed prior to disposal, and solids handling accounts for as much as 30 per cent of a wastewater treatment facility’s costs. As with all forms of energy, continuity of supply is paramount so the plants that process sewage sludge into pellets or granulate are continuous operations that cannot stop for adhoc repairs and refurbishment. But on its passage through sewers, sewage sludge becomes contaminated with flood debris, sand, grit, deposits from environmental structures, residue from the land mass, plus metallics, and plastics. Sand and
grit are a major problem, due to their high silica content. They are highly abrasive, causing problems of wear and erosion with the equipment used to treat and process the sludge: equip- ment such as pipework, augers, screw casing, mixers, blenders, driers, sepa- rators, screens, centrifuges, mechani- cal conveyors, presses, driers, ducting, filters housings, fans and fan casings. All of this equipment can benefit from wear protection in order to deliver overall systems that reduce erosion and cavitation and improve material flow. However, a survey by wear protection specialist, Kingfisher Industrial, has found that wear protec- tion isn’t optimised to its full benefit, and that water industry awareness of the cost and operational benefits of wear protection in the processing of wastewater and sludge is minimal. “We have identified that the vast
Sewage contains 10 times the amount of energy needed to treat it
Kingfisher
Industrial Motion T: 01384 410777
www.kingfisher-
industrial.com Enter 305
Left: A process plant that is equipped with a well designed wear protection system requires little or no maintenance over the lifetime of the installation
Skid-steer loader suits recyling industry
aul Riddel Skips based in Horncastle in Lincolnshire, has purchased what is said to be the UK recycling industry’s first Bobcat S630 skid-steer loader for use in the company’s metal recycling and waste disposal operations. The new S630 loader is used all day on the 2.2 acre site, sorting materials such as scrap metal, plastics, construction rubble and wood into piles, so that they can be loaded into dedicated containers by a fleet of excavators equipped with grabs and other attachments. The compact size and manoeuvrability of the S630 skid-steer loader are suitable for this application working in the spaces between the larger material handlers, providing high performance and durability. Company owner, Paul Riddel, says: “I’m really impressed with the enhancements on the new S630 which is even more robust than its predecessor and features a larger cab for increased operator comfort and productivity. The ability to clean the S630 by pressure washing both inside and outside the machine is also a great asset. The S630 has been built to work long hours on demanding jobsites and requires minimal time for routine maintenance at the start of the day.” AMS Bobcat T: 01724 289009
P
www.amsbobcat.com 14 Enter 306
majority of waste and water treatment plants depend on heavier grades of stainless steel to counter corrosive and abrasive effects of handling and treat- ing wastewater and sludge,” says John Connolly, MD of Kingfisher. “In an attempt to improve the life expectancy of critical plant and equipment, some processors use polymeric composites and glass flake coatings applied by brush, trowel or sprayed on. They have also applied hard metal deposits by traditional welding methods and, albeit these processes are in some instances suitable, they are not an ideal fit for many areas of the process. These methods of protection have extended the service by an improved margin; however, they do not eradicate the problems. We think the awareness of suitable technology solutions to reduce wear and corrosion, cut main- tenance costs and optimise the whole life costs of plant, is limited.” Kingfisher has calculated that, on average, users of its wear protection systems - polymer, ceramic and metal- lic - benefit by a factor of at least five times their initial outlay, with many installations benefiting from wear life of up to 20 years following appropriate wear treatment.
If a system is designed with wear protection from conception, equip- ment costs can usually be reduced, as the system chosen to protect the equipment can often remove the requirement to manufacture compo- nents using heavier grades of material. Take a pipeline, for example: if a wear protection lining system is used, the user can specify thinner walled pipe, as the lining will provide the protection. This might mean 5mm wall thickness for the pipe rather than 10mm, with a commensurate 50 per cent saving in cost. This downsizing is possible because the pipework becomes a carrier for the wear resistant lining, the synergy of the two meeting the requirements for pressure, temper- ature and wear protection.
A process plant equipped with a well designed wear protection system has little or no maintenance require- ments over the installation’s lifetime. “The requirement for green energy means that the demand for energy from waste can only grow,” says Connolly. The technology for process- ing sludge is still relatively new, so treatment plants have a breathing space in which to adopt best practice in wear protection.”
MARCH 2011 Factory Equipment
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