Heat exchange in the hearth of a blast furnace operating with combined blast parameters

Heat exchange occurs most intensively in the hearth of the blast furnace (B F) and determines metal quality, furnace productivity and operating paramet ers. The heat and chemical energy needed for the BF process is generated in the raceways. This paper is dedicated to the advancement of the heat exchange theory in t he hearth of a BF operating with combined blast. The heating processes of p roducts of melting in the raceway and in the liquid bath of the hearth and the effect of pulverized coal injection (PCI) on heat exchange in the oxidi zing zone and its extension are studied. An increase in furnace productivity requires additional heat power for the heating of pig iron and slag and therefore a rise in flame temperature. PCI increases radiation in the raceways, thus permitting BF operation with a l ower flame temperature. These theoretical conclusions are confirmed by calculations for two BFs in the Ukraine and Spain and by statistical analysis of the operation of the m ajority of BFs in EU countries. At one BF in Germany the effect of PCI and other combined blast parameters on the raceway extension was investigated u sing the laser technique.