Aerotherm and Steinmüller Africa (a member of the Bilfinger Power Systems group) collaborated to help improve the performance of a coal-fired furnace at the Komati Power Station in South Africa, as part of a recent return-to-service project involving that station. As the decades-old furnace was re-introduced to service, some combustion-related problems resulted, in part because the moisture level in the coal that was used exceeded original design limits. The furnace comprises a common windbox and 12 pulverized-fuel (PF) swirl burners.
The ultimate business goal of the South African power utility company operating the Komati station is to provide sustainable electricity solutions; a supporting objective is to avoid unplanned downtime at the station. The technological goals of this project – to improve flame stability and coal-air mixing for more complete & reliable combustion and furnace performance – were intended to help achieve that business goal & objective.
First, STAR-CCM+ was used to diagnose problems with flow & pressure in the baseline design. Then, by using additional simulations to evaluate the performance possible with numerous design modifications, they were able to more fully explore the feasible design space and develop an optimized new design that achieved the aforementioned goals. The engineering solution involved strengthening the reverse flow toward the burners and significantly improving flow uniformity.
The newly designed burners were installed in April 2013 and operated during the rest of that year with no stability problems. As of March 2014, combustion stability has been maintained without the need for auxiliary oil-burner firing, in spite of excessive coal moisture content.