Drax Power Station, a 3,960-MW six-unit facility located in North Yorkshire, England, is the largest power plant in the UK. It was constructed in two stages, with the first three units completed in 1974 and Units 4, 5, and 6 finished in 1986.
As a baseload plant, the station’s coal hopper shed is in use 24/7, but the lighting in the area had deteriorated over the years. Performing maintenance on the 15-year-old high-pressure sodium (SON) light fittings was difficult, and dust and dirt accumulation had become a problem. Access limitations made biannual maintenance tricky, and the track that provided bus power for the existing light fittings had been damaged during previous maintenance tasks. Replacement of failed SONs consumed a lot of time, so a more reliable and higher-performance lighting solution was desired.
The Light-Emitting Diode Solution
Matthew Glazier, one of Drax’s electrical maintenance technicians, came across Hadar Lighting while the company was displaying its product line during a procurement open day, which is essentially a vendor exposition where engineers can peruse products in search of project solutions. After conducting a more thorough evaluation of the company’s offerings, Drax asked Hadar’s sales team to provide a recommendation for improving the plant’s coal hopper shed lighting.
The team responded with a proposal to replace 20 400-W high-bay track-mounted SONs and 30 70-W trackside fittings with 20 160-W light-emitting diode (LED) high-bay lights and 15 100-W LED floodlights. Assured that the new scheme would be far superior to the existing lighting arrangement, Drax agreed to proceed with the project.
Two weeks later, the LED fittings were delivered. The fittings needed to be installed above rail tracks that ran over giant hoppers into which coal is routinely dumped. Rather than installing scaffold over this very dangerous area, the installation team chose to use a rail-mounted scissor lift to perform the task. That decision allowed installation to be completed in only six days.
Saving Time and Money
Although Drax generates its own electricity, improving energy efficiency is a corporate objective. By reducing the total number of fittings from 50 to 35 and total wattage from 11,050 W (the 400-W high-bays actually drew 440 W and the 70-W wall packs drew 75 W) to 4,700 W, the plant has been able to cut its energy use in the coal hopper shed from 4.74 W per square meter (W/m2) to 2.02 W/m2.
LED fittings run at a much lower temperature than the SONs and are designed to dissipate driver heat away from the fittings using fins that act as a heat sink. The rim design incorporates small, machined apertures that draw air from below the fitting up and over the face and fins, providing airflow in much the same way as a chimney does, thus creating small eddy currents around the fitting. In addition to cooling the components, this also helps to remove dirt that clings electrostatically on the face and body of the fitting. The LED luminaires carry five-year warranties, so lamp failure is less of a concern, and relamping can be scheduled at times to suit the plant, thus reducing the maintenance burden.
“We looked at a range of fittings from other manufacturers as alternatives, but Hadar was a perfect fit. The quality and ruggedness of their fittings is great. It’s solid. The coal hopper lighting now speaks for itself. It’s a 100% improvement,” Glazier said (Figures 4 and 5).
4. Dark and dreary. The high-pressure sodium lighting previously installed in Drax’s coal hopper shed was not particularly illuminating. Courtesy: Hadar Lighting/Steve Bowart
5. Seeing is believing. The newly installed light-emitting diode (LED) lighting has brightened up the area while saving on energy costs. Courtesy: Hadar Lighting/Steve Bowart
The glare-free LED fittings provide a much better working environment throughout the shed, and everything now looks clear and crisp. ■
—Steve Bowart ([email protected] hadar-lighting.com) is business development manager for Hadar Lighting.