Thermo-kinetics, mass and heat balance in an energy optimizing furnace for primary steel making

Abstract

Energy optimizing furnace (EOF) is a primary steel making reactor, where the autogenous exothermic reaction heat, associated with the solute oxidation is utilized for making the steel. The thermo-kinetic reactions of the steel making process have been evaluated in the world's largest, 65 ton EOF, at JSW Steel Ltd., Salem. The solute oxidation as a function of blow time and Si content was evaluated. The mass balance analysis showed that oxygen from the furnace atmosphere has to be entrained by the oxygen jet from the inclined supersonic lance, to completely oxidize the solutes in the melt. The heat balance showed that the power of 352 kWh per metric ton of hot metal is generated by the solute oxidation along with the post combustion. The characteristics of the inclined single hole-supersonic oxygen jet on the molten bath are brought out. Other operational aspects of the process are elaborated.

A Static Model for Energy‐Optimizing Furnace

“…The entrainment of air from the furnace atmosphere is also reported. [1,5] In the basic oxygen process, the rapid oxidation of solute elements mainly happens at the slag-metal interface or the slag-metal-gas interface of the emulsion zone in the BOF. [6] Considering the comparable tap-to-tap time for EOF [5] to that for BOF, a similar mechanism is expected in EOF as well.…”

“…[1,5] In the basic oxygen process, the rapid oxidation of solute elements mainly happens at the slag-metal interface or the slag-metal-gas interface of the emulsion zone in the BOF. [6] Considering the comparable tap-to-tap time for EOF [5] to that for BOF, a similar mechanism is expected in EOF as well. This was further verified by collecting samples of entrapped metal droplets in slag samples in EOF as shown in Figure 2.…”

“…As per the former design, the main function of the atmospheric injectors was post‐combustion. [ 1,2 ] Vidhyasagar et al [ 5 ] reported that due to the modifications in the original designs, atmospheric injectors also contribute to the solute removal, however, it was not quantified due to the lack of required process control tools. The entrainment of air from the furnace atmosphere is also reported.…”

“…From the previous heat and mass balance studies carried out by Vidhyasagar et al [ 5 ] at JSW Steel Ltd. Salem works, the average quantity of the mass flow was brought out. Fifteen heats were monitored in that experiment and based on that some of the parameters (i.e., slag and sludge) in the outputs were calculated.…”

“…Based on a few previous off‐gas measurements, the air inspiration is calculated with the help of post‐combustion. [ 5 ] In the heat balance, the input heat was considered as the hot metal heat and the heat from the chemical reactions. In the output heat except the heat taken away by the radiation, refractory, and water‐cooled panels, other outputs are quantified.…”