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Show Paper No. 5 EFFECT OF COAL QUALITY ON THE PERFORMANCE OF LOW-NOx BURNERS M E Morgan The International Flame Research Foundation §YMMARY Although much information is available on low-NOx coal combustion, it is still difficult to predict the performance of any particular coal in a low-NOx burner. Research on low-NOx combustion has been carried out at the IFRF for the last decade using a wide variety of burners and coals at the 2.5 MW scale. In addition, a coal characterisation programme has been undertaken to obtain fundamental information about the coals studied in a well controlled environment. The results of both of these programmes have been reviewed in an attempt to explain the effect of coal quality. When the coals were fired under normal, unstaged conditions, the NOx emissions were a clear function of high temperature volatile yield and the nitrogen content of the volatile matter. Under staged combustion, the variation in NOx emissions was much smaller, and it was shown that the optimum burner design and operation was a function of the coal being fired. 1 INTR9PUCTION Legislation is currently being enacted throughout the world to limit the emission of NOx from stationary sources. One of the largest contributors to this problem is the combustion of pulverized coal. Virtually all of the combustion-equipment manufacturers are involved in the development of low-NOx coal burners, but a significant amount of questions still remain. One of the ,most important areas is the effect of coal quality on burner performance. Research on low-NOx combustion has been carried out at the IFRF for the last decade using a wide variety of burners and coals at the 2.5 MW scale [1-5]. Three main burner types have been studied: an externally air-staged burner, an internally air-staged burner, and an air-staged precombustor burner. All three burners are designed as retrofit burners for wall-fired combustion units. A wide range of coals have been employed with ranks from low-volatile bituminous to lignite. In addition, experiments have been conducted with a plug flow reactor 1 |
