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Show detection equipment works even when the kiln is dusty. There were some commissioning adjustments required initially. As time goes by, and plant personnel have become more familiar with the equipment, the new system is much easier to light up than the old equipment. Shortly after the installation of the burner a kiln camera was added to complete the installation from a safety and process standpoint. The combination of the new burner management system and kiln camera has greatly improved the safety of the burner system. The burner management system meets all Factory Mutual Insurance requirements. The BMS consists of a programmable logic controller (PLC) which was interfaced to existing plant electrical and control systems. The new burner employs a miniature precessing jet gas pilot burner with an individual gas valve and control system. The ignition of the main gas burner is accomplished via this pilot burner using a flame front ignition system. 5 CONCLUSIONS AND FUTURE DEVELOPMENTS The installation of a combined fuel precessing jet burner at the Ash Grove Cement Company's Durkee plant has produced an average increase in output by up 1 1 % as well as an average reduction in N Ox emissions by up to 3 7 % . Kiln production has increased by as much as 1 1 % and N O x emissions have fallen by 37%. In addition, to the increased output there has been a specific fuel saving of 5 % . These benefits have been achieved when firing a range of fuel types, but predominantly with 100% gas. The overall safety of the burner system has been improved greatly. Refractory life is expected to remain good and no significant changes in clinker quality have been observed. Precessing jet technology provides an opportunity to reduce NOx, increase capacity and reduce fuel consumption. Future projects include a dual fuel burner firing coal and gas in a lime kiln in Ohio. Presently the kiln fires 1 0 0 % coal to produce high calcium and dolomitic lime. Cofiring technology will be used to control the build up of ash rings which, at times, are forcing a kiln shutdown weekly. The development of a 100% coal burner using a precessing jet of air is in progress. Preliminary data (14) indicates that there is potential for significant N O x and C O reduction when using a precessing jet instead of conventional swirl air. 6 References 1. Nathan,G.J. and Luxton,R.E. (1992a) vvMixing Enhancement by a Self-Exciting, Asymmetric Precessing Flow-Field", Transport Phenomena in Heat and Mass Transfer, ed. ReizesJ.A., Elsevier, ISBN 0 444 89851 4, vol 2, pp 1297-1307. 2. Nathan,GJ. and Luxton,R.E. (1992b), vvThe Flow field Within an Axi-symmetric Nozzle Utilizing a Large Abrupt Expansion", "Recent Advances in Experimental Fluid Mechanics', Zhuang, F.G., ed., International Academic Pub., pp527-532. 3. Nathan,G.J., Luxton,R.E. and SmartJ.P. (1992), ~ Reduced NOx Emissions and Enhanced Large Scale Turbulence from a Precessing Jet Burner", Twenty-fourth Symposium (International) on Combustion, The Combustion Institute, 1399-1405. 4. Manias.C.G. and Nathan,G.J. (1993) ~The Precessing Jet Gas Burner - A Low NOx Burner Providing Process Efficiency and Product Quality Improvements", World Cement, March, pp 4-11. 5. Balendra,S.A., Manias.C.G. and Rapson,D.S. (1996), vvLow NOx Lime Production Using a Gyro- Therm Burner", Rock Products. 6. Rapson.D.S., Stokes,B. and Hill,S.J. (1995), vvKiln Flame Shape Optimisation using a Gyro-Therm Gas Burner", World Cement, (July). 15 |
