To minimize oxides of nitrogen (NOx) emission, maximize boiler combustion efficiency, achieve safe and reliable burner combustion, it is crucial to master global boiler and at-the-burner control of fuel and air flows. Non-uniform pulverized fuel (PF) and air flows to burners reduce flame stability and pose risk to boiler safety by risk of reverse flue gas and fuel flow into burners. This paper presents integrated techniques implemented at pilot ESKOM power plants for the determination of global boiler air/flue gas distribution, wind-box air distribution and measures for making uniform the flow being delivered to burners within a wind-box system. This is achieved by Process Flow Modelling, at-the-burner static pressure measurements and CFD characterization. Global boiler mass and energy balances combined with validated site measurements are used in an integrated approach to calculate the total (stoichiometric + excess) air mass flow rate required to burn the coal quality being fired, determine the actual quantity of air that flows through the burners and the furnace ingress air. CFD analysis and use of at-the-burner static, total pressure and temperature measurements are utilized in a 2-pronged approach to determine root-causes for burner fires and to evaluate secondary air distribution between burners.
Archary H., Jestin L.M., Roohani H., 2012. Online measurement and condition based maintenance of pulverised fuel vertical spindle mills. POWER-GEN AFRICA 2012. Johannesburg, South Africa, 6-8 November 2012.
Brown R., 2004. Coal and air flow measurement and control at Allegheny’s Armstrong Station. EPRI, March 29, 2004. Available at: http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000000001009374
Department of Trade and Industry, 2001. Technology status report. Pulverised fuel (PF) flow measurement and control methods for utility boilers. Available at: http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file19294.pdf.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.