Weir Minerals Africa supplied 130 Linatex® feeder ejectors to Eskom’s Camden coal-fired power station near Ermelo in Mpumalanga to replace all the facility’s existing units. This substantial order, initiated by Eskom to improve the power station’s operational efficiencies, was supplied on a staggered basis together with associated ash valves, water valves and tie-in pipes. Weir Minerals Africa also undertook the installation and commissioning and will provide technical support for the life of the equipment.
Winchester Maphosa, Weir Minerals Africa’s product manager for comminution products and screens, says the order follows the successful trial of a set of 18 feeder ejectors conducted at one of the power station’s eight 200 MW units in 2013.
“The trial proved the efficiency of these units so conclusively that they were put into permanent service,” he says. “During the first working shift a dramatic increase in efficiency was noted and the entire unit completed dusting operations in less than half an hour compared to more than an hour with the existing units. Each of the remaining power station units are now being supplied with a set of 18 feeder ejectors.”
Feeder ejectors are not new technology and have been in use since the first coal fired power stations were established in South Africa. They use no power and are environmentally friendly. Feeder ejectors were developed and supplied by RJ Spargo during the construction of these power stations and later supported by Linatex when the RJ Spargo name changed in 1994. With the Weir Minerals acquisition of Linatex in 2010 these feeder ejectors are now supplied and supported by Weir Minerals Africa. Maphosa reports that since 2010 there has been increased demand from the power generation sector for these locally manufactured units.
Thermal power stations using pulverised coal fired boilers produce the major portion of their ash-make in the form of grit. This is separated from the flue gases by electrostatic precipitators and collected in banks of hoppers that are integrated with the boilers and located upstream from the chimneys. Feeder ejectors are fitted at the bottom discharges of the grit hoppers to extract the collected grit and discharge it with the help of hydro-jets to sluiceways leading to the main ash sumps. The grit and water slurry produced by the feeder ejectors that gravitate to the ash sumps is finally pumped away to disposal sites.