Development of an analytical equation for calculation of the blast furnace fuel rate

Abstract

Analytical expressions are developed for calculating the specific fuel rate and the direct reduction rate for the iron blast furnace process as a function of blast conditions as well as other control parameters for the process. These are relevant for carbonaceous as well as hydrogenaceous gases in the system. The equations are based on an oxygen balance and a heat balance for the bottom half of the furnace, separated from the upper half at the location where equilibrium of the gas phase with wustite and iron is assumed to occur and where the temperatures of the gas and solid streams are approximately equal. The mass and heat balances employed are those which are the basis for the classical Rist diagram. Equations were also derived for the constraints of the Carbon-Direct Reduction (C-DRR) diagram, showing that this diagram and the Rist diagram emphasize different variables of the same model. An interpretation of the constraints operating in the diagrams is also given from the point of view of blast furnace operating practice.