Results of Burning Alternative Fuels

Co-processing of various alternative fuels in cement kilns has become meanwhile more or less state-of-the art in many areas of the world. It has become more established and accepted by the industry as prices for primary fuels are steadily increasing. Another reason is the global goal to reduce greenhouse gas emissions (CO₂). To successfully fulfill individual production targets, process related influences resulting from burning alternative fuels and best available technology have to be well balanced. A goal- oriented process engineering with proven Calciner- and Burner technology and adequate Bypass solutions is necessary to achieve highest possible replacement of fossil fuels combined with "trouble-free" process conditions. Norwegian Cement producer started already in the eighties utilizing alternative fuels motivated by environmental, economical and societal benefits at the Brevik plant. The portion of alternative fuels has steadily increased with different steps of kiln modification. Starting first with calciner and riser duct firing of secondary fuels up to a certain point where combustion- and flow-related limitations occurred. In the next modification step a combustion chamber was installed to an extended calciner for sufficient residence time. Together with the installation of the chlorine bypass system the process goals as total substitution rate of 60% maintaining the clinker production capacity and elimination of operational problems could be achieved. After 4 years of successful operation with several improvement measures, alternative fuel firing is further optimized, especially at the kiln main burner in order to achieve highest possible substitution rates at most economic production conditions in the permissible framework of increasing emission regulations.