Wear liners protect plant and improve efficiency at Didcot A 23 February 2012

Problems caused by impact and abrasion wear, as well as mass flow issues on Didcot A power station's coal handling plant, in Oxfordshire, have been solved by Kingfisher Industrial.

A combination of Kingfisher's ceramic, metallic and polymer linings on hoppers, transfer chutes, bunkers and feeder sections, is providing greatly improved wear life, while also reducing maintenance and improving coal throughput.

The 2,000MW Didcot A power station, operated by RWE npower, was designed as a coal-fired unit, but is now tri-fuelled, with three of the four 500MW generating plants having been converted to dual-firing for natural gas, while all four also burn biomass, such as sawdust and wood chips.

Kingfisher managing director John Connolly explains that the company's involvement began at he coal reception hoppers where the fuel is stored following delivery via train.

"If it was just coal that was being handled then it's relatively easy to manage," comments Connolly. "However, because there are foreign particles – metallic, wood and debris – protection measures have to be taken to ensure that contamination doesn't become a problem.

"It's also important to get the material away very quickly to reduce the cost of waiting time associated with the unloading operation," he adds.

Kingfisher, he explains, assisted with coal discharge by lining the reception hoppers with a combination of K-Flow ferritic stainless steel and K-Plas polyethylene.

"We've used the various grades of material and various thicknesses to counter both the impact and friction induced abrasion, and the wear associated with discharging the material from the rail wagons," states Connolly.

It's a similar story with the transfer chutes, although these have been lined with Kingfisher's ceramic lining materials. "The combination of K-Alox, K-Bas and K-Zas materials, supplied in various thicknesses, offers resistance to all types of wear encountered and guarantees long term protection against perforation," says Connolly.

Kingfisher also re-designed some of the internal geometry of the post-transfer chute bunkers, using radius sections, and lined them, again with K-Flow ferritic stainless steel.

"We applied this material using traditional welding and mechanical fixing, which provided a totally seamless lining inside the bunker," recalls Connolly.

"This delivers a high degree of wear protection, due to its hardness of about 240 Brinell. It also gives them a very low coefficient of friction, as a result of the polished stainless steel finish. In addition, the fact that the lining is fully welded prevents any internal corrosion taking place in the steel substrate."

Interestingly, as part of the project, Kingfisher was also tasked with improving mass flow through the volumetric feeders that weigh and distribute coal into the pulverising mill.

Because of the amount of wear in the associated pipework, it has also been lined with K-Alox, K-Bas, K-Cast, K-Sil ceramic and K-Hard metallic materials – each selected according to the different wear rates that occur at bend sections, trifurcators and non return valves, where abrasion is at its greatest.

Brian Tinham

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