Burners for alternative fuels
Alternative fuels offer major cost and environmental benefits but they almost always have some negative side-effects on process stability, quality and capacity. Neil Taylor and Raine Isaksson of Isaksson-Taylor Management Consultants look at some basic kiln burner requirements needed to make the best use of alternative fuels.
Figure 1: typical characteristics of a recirculatory kiln flame
Alternative fuels can introduce species which cause buildups and blockages, and then add insult to injury by creating reducing conditions which make the recirculation problems worse. Their generally poor combustion characteristics also make the kiln flame longer, which lowers thermal efficiency. The longer flame usually changes the clinker mineralogy and reactivity, affecting cement properties like strength, workability and colour. Alternative fuels also introduce more false air, moisture and ash into the kiln system, which increases variability and reduces kiln capacity. But these problems can be made much more manageable by ensuring that the alternative fuels are burned efficiently through a suitable burner.
