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COMMERCIAL FEATURE Refurbishment and life extension of SA’s power plants R ehabilitation or new built? This is a key question to be answered by plant operators, very often during the lifetime of existing plants. Experience reveals that refurbishment and lifetime extension of existing plants is a good economical approach to assure generation capacity. Very often it can be accompanied by a capacity increase through new technologies. This new capacity is cheaper than new built capacity and such projects are typically executed in a shorter time with fewer project risks. A refurbishment aims at improving reliability of a power plant which depends very much on the performance of the firing system. Burners play a key role as they determine the requirements on furnace design and coal preparation. This is particularly important for South African coal with its very special combustion characteristics. State-of-the-art burners offer a good potential for performance improvements due to their flame stability and low sensitivity to changing coal properties. Today burners are designed by computational fluid dynamics (CFD) analysis to get a defined flow field in the near burner zone, which is crucial for stable ignition and pyrolysis under oxygen lean conditions. If this is achieved, the NO x emission is low and burner operation is not sensitive to changing coal properties, which is a characteristic of the Babcock Borsig Steinmüller product. The burner is designed for front wall or opposed wall arrangement. The combustion air is staged through separate barrels for core air, primary air, ESI AFRICA ISSUE 2 2014 secondary air 1 and secondary air 2. Core air is used for ignition of the flame by oil or gas. The primary air/ coal mixture is swirled, and at the outlet a flame holding toothed ring is applied. Both secondary air flows are swirled and deflected away from the near burner flame by special cones. Very often boiler operation is affected by deteriorating coal properties, making it very difficult to keep the units online and provide the required generation capacity. If burner modernisation is combined with an improvement of the entire coal handling and preparation system, all prerequisites are on hand to get a reliable operation independent of coal properties. Depending on the requirements of remaining life, a lifetime assessment can determine which components of the pressure part of the system should be refurbished, modified or even completely replaced. There is no general rehabilitation approach for every power plant: each site has special conditions and constraints. The perfect set of measures is determined by an analysis of existing problems and a compromise with regard to budget and allowable outage time. At Steinmüller Africa and its Germany-based sister company Babcock Borsig Steinmüller, both subsidiaries of the international group Bilfinger SE, you have experts and a partner when it comes to steam generation matters. The company’s presence in the southern African market, spanning over 50 years, is testimony to its unrivalled expertise in the steam generation industry. Services offered range from feasibility studies right through to the design, manufacturing, construction and maintenance of boiler firing systems and pressure parts. At the group’s local South African based manufacturing facilities, it also specialises in fabrication of high- pressure feed water heaters, pressure vessels, pipe supports and compensators and its on-site maintenance crews provide support to the power generation and petrochemical sectors. ESI Burner flame. BBS low-NO x burner for hard coal. 61