Modeling results for the preheating of scrap by means of coal pieces in a converter

Abstract

One of the best and least expensive means of improv� ing the thermal balance in converter smelting and conse� quently reducing the hotmetal consumption is preheat� ing of the metal scrap by means of carbon fuels (1-5). The difficulty of using fuel pieces for preheating is pri� marily associated with the organization of rational gas� dynamic conditions in the converter's working space, by heating the coal in the converter to the ignition point. In these conditions, the supply of solid fuel to the bot� tom of the unit in constant industrial operation increases the lining wear, while the supply of lime to the bottom of the converter, like the charging of lime with scrap, considerably reduces the efficiency of heating. Therefore, an effective means of preheating scrap in the converter is to load the solid fuel on top of the scrap, under an oxygen jet (5). Hightemperature modeling of scrap heating in nearproduction conditions may be based on modern� ized equipment (6). Coal (grades TOM and SSO; 10- 15 mm fraction) is charged on top of the scrap (25 × 40 mm pieces). Oxygen is supplied through an upper fournozzle tuyere, at a rate of 0.10 m 3 /min; the inten� sity of the blast is boosted to 0.15-0.17 m 3 /min. The ignition and combustion of the coal under oxygen jets poses no particular difficulties (Fig. 1). When the coal is in contact with the hot lining, we observe the intense liberation of igniting products of coal pyrolysis. This results in rapid ignition of all the solid fuel. Overall, with regulation of the rate of oxy� gen supply, stable heating of the scrap pieces to red heat is ensured within 4-7 min, without melting of the scrap to form an oxidized slag-metal melt (Fig. 2). No