Kingfisher Industrial has demonstrated its ability to provide solutions to problems of wear, due to impacts and sliding abrasion, and to deliver improved efficiency via increased mass flow, on the coal handling plant at Didcot A power station in Oxfordshire. The combination of Kingfisher’s ceramic, metallic and polymer linings on hoppers, transfer chutes, bunkers and feeder sections, is providing greatly improved wear life from the Didcot coal handling and combustion plant; at the same time reducing maintenance and improving coal throughput.
Didcot A is a tri-fuel power station in Oxfordshire, owned and operated by RWE npower. The station, which began commercial operation in 1970, can generate 2,000MW of electricity - enough power to meet the needs of some 2 million people.
Didcot A was originally designed as a coal-fired station. Three of the four 500MW generating units have now been converted to dual-firing, enabling the station to use natural gas as an alternative to coal. In addition, the station has the capability to use biomass fuels such as sawdust and wood chips on all four units.
Kingfisher’s involvement at Didcot A began upon receipt of the coal, at the 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,” said Kingfisher MD John Connolly. “However, because there are foreign particles – metallic, wood, and debris, mixed in with the coal, protection measures have to be taken to ensure that this contamination doesn’t become a problem throughout the rest of the plant. It’s also important to get the material away very, very quickly in order to reduce the cost of any waiting time associated with the unloading operation thus avoiding demurrage costs.
In order to aid discharge of the coal, we’ve lined the coal reception hoppers with a combination of K-FLOW ferritic stainless steel and also our K-Plas polyethylene lining. 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.”
Once discharged, the coal is fed onto the conveyor belt; it then goes through a series of transfer chutes. These coal transfer chute are used take coal from the unloading station and it can fed directly up to the station bunkers or it can be stockpiled for storage and reclaimed at a later stage. Eventually all product is fed back onto conveyors and discharged onto the tripper conveyor that feeds the bunkers. As the transfer chutes are subject to impact, friction and sliding induced abrasion, Kingfisher has lined these units with its ceramic range of lining materials. This combination of K-ALOX, K-BAS and K-ZAS materials supplied in various thicknesses offers resistance to all the different types of wear encountered and guarantees long term protection (10-12 years-plus) against perforation of the fabrication, and against any discharge onto the floor.
The station coal bunkers, which are fed from the transfer chute, have also been optimised by Kingfisher. Here, the main problem was the amount of discharge that was being achieved into the feeders, as a result of whole combination of different bunker lining materials. Continual discharge into the feeders is very important in guaranteeing that the correct amount of tonnage is fed down to the coal mill to ensure an efficient milling process, and correct distribution up to the burners.
“What Didcot wanted here was to achieve mass flow,” said John Connolly; “so we re-designed some of the internal geometry of the bunkers using radius sections, and then we lined them with our K-FLOW ferritic stainless steel. We applied this material using traditional welding and mechanical fixing, which provided a totally seamless lining inside the bunker. This delivers a high degree of wear protection, due to its true 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 internal steel substrate.”
Also as part of the project of achieving improved mass flow, Kingfisher was tasked with removal of the existing volumetric feeders, and the installation of new units. The feeders weigh and distribute coal at different rates, ensuring that between 30 and 40 tonnes per hour of coal is always discharged into the mill at any one time.
From the gravimetric feeders, the coal is deposited downward into the mills. On top of the mills are three piping ducts. One of these handles coal into the mill itself; the remaining two provide the outlets for coal that has already been milled. As the coal comes down into the mill, it is feed out onto a rotating table, and then ground down. This results in a micron sized powder, which is dried and conveyed with a primary air flow prior to exiting the mill vertically via the two pulverised fuel outlets, which are protected using a range of ceramic and metallic liners.
Because of the amount of wear that takes place in the associated pipework, it is lined with Kingfisher’s range of K-Alox, K-BAS, K-CAST, K-SIL ceramic and K-HARD metallic materials. These offer the key benefit of countering the different amounts of wear that occur in for example; bend sections, trifurcators and non return valves (NRV’s), where abrasion is at its greatest.
Kingfisher has also completed the loop at Didcot by providing the lined pipes that remove the ash from the system; using water to both cool and suspend the ash in a fluid for easier transport, the very fine residue is still extremely abrasive and requires expertise to ensure the pipework lasts in this final application at the site.
Summing up the project, John Connolly said: “What we have demonstrated at Didcot A is that wear protection is one of the key technologies in helping operators meet the requirements for reliable, efficient equipment in the power generation industry. At Kingfisher Industrial we are leading the way by introducing new materials to combat the abrasive effects of both coal and ash; and we are continually increasing the warranty periods offered, based upon the extended lengths of time our existing systems have been operating within the industry. We aim to continue improving what we offer the industry, and feel confident that our portfolio of services will continue to grow and assist power utilities in meeting its key performance targets.”
About Kingfisher Industrial
Kingfisher Industrial provides wear solutions for process plant used to convey, process or store bulk solid materials, in either dry or hydraulic states. With its range of ceramic, metallic and polymer protection systems, Kingfisher can overcome wear problems; engineering suitable protection systems that can add many years’ of life to a plant, and in some cases outlast the design life of a process completely.
These solutions cater for the operating criteria, budget and life cycle of either new equipment - particularly when initially installed - or existing equipment, which can be retrofitted with a protection system to add to its current asset value.
Photo Captions
Picture 1: Didcot A is a tri-fuel power station in Oxfordshire, owned and operated by RWE npower. The station, which began commercial operation in 1970, can generate 2,000MW of electricity - enough power to meet the needs of some 2- million people.
Picture 2: The raw coal arrives by rail and is conveyed out onto the stockpile via an underground conveyor, or fed directly into the station itself. The coal reception hoppers are lined with various grades of material and various thicknesses to counter both the impact and friction induced abrasion.
Picture 3: The coal from the stockpile, or rail carriages, passes through a transfer station where inclusions in the coal stream can cause excessive wear before they are removed.
Picture 4: Coal is fed onto the conveyor belt via a chute that has been lined with a range of tough ceramic materials. This combination guarantees long term protection (10-12 years-plus) against perforation of the fabrication.
Picture 5: Kingfisher was tasked with removal of the existing volumetric feeders, and the installation of new units.
Picture 6: The wear protected pipework conveys fine pulverised coal through to the burner section of the plant.
About Kingfisher Industrial
Kingfisher Industrial provides wear solutions for process plant used to convey, process or store bulk solid materials, in either dry or hydraulic states. Such plant often suffers premature wear due to handling large quantities of materials at velocity in a constant operational cycle. With its range of ceramic, metallic and polymer protection systems, Kingfisher can overcome wear problems; engineering suitable protection systems that can add many years’ of life to a plant, and in some cases outlast the design life of a process completely. These solutions cater for the operating criteria, budget and life cycle of either new equipment - particularly when initially installed - or existing equipment, which can be retrofitted with a protection system to add to its current asset value.
Editor Contact
DMA Europa Ltd : Roland Renshaw
Tel: +44 (0) 1299 405454 Fax: +44 (0) 1299 403092
Web: www.dmaeuropa.com
Email: roland@dmaeuropa.com
Company Contact
Kingfisher Industrial : John Connolly, MD
Tel: +44 (0) 1384 410777 Fax: +44 (0) 1384 410877
Web: www.kingfisher-industrial.com
Email: enquiries@kingfisher-industrial.co.uk