Stability Limits of Pulverised Coal Burners

This note describes some stability explorations on a pulverised coal-fired laboratory furnace. There is little to be found on this subject in the literature with the exception of Hein and Leuckel (1969), Beer and Chigier (1969) and Wolanski and Wojcicki (1974), since full-scale tests are unacceptably dangerous and because of the scarcity of suitable laboratory test rigs, at least in institutions, such as Universities, able to publish freely the results. The present furnace is a vertical cylinder, axially down-fired by a variable swirl burner. The cylinder diameter and length are respectively 0.6 and 3 m; the near burner cylindrical walls are refractory lined for a distance of 1.5 m from the burner plane and water cooled over their remaining length. The burner has primary and secondary tubes in the conventional double concentric layout terminated by a quarl having a half angle of 24 degree . Swirl is imparted to the secondary stream only. Full details of the test furnace and burner may be found in Hassan et al. (1984).