Treatment of multiple injections in the iron blast furnace by the rist diagram
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I.
INTRODUCTION
C O N S T R U C T I O N techniques for the graphics study of injections in the iron blast furnace were explored in detail in a recent article, m The constructions at issue consisted of lines and of pivots governing their rotation in the diagram as an injection is made for a fixed set of process parameters. Four key pivots were studied with respect to an injection, namely, pivot I for the primary operating line, pivot J for the thermal balance line, pivot K for the coke line, and pivot L for the fuel injection line. The earlier article m is referred to for a detailed description of the constructions identifying each of these pivots in the operating diagram. At issue regarding injections is the location in the diagram of the pivot abscissae, which depend on the characteristics of the injectant. The pivot abscissae XI, Xj, XK, and XL for the key primary injectants C, CO, CO2, H~, H20, and plasma heat were shown to locate easily and in a manner characteristic of the stoichiometric and thermal parameters of each injectant, m In fact, since the parameters of any multiple injectant can be reduced to a weighted sum of parameters for its primary components, a method must exist which can employ the abscissae referring to these components to arrive at the pivot abscissa for the multiple injectant. This method is now developed with interesting results and useful applications. II. BASIC CONSIDERATIONS FOR T H E T R E A T M E N T OF M U L T I P L E I N J E C T I O N S There are two ways to treat multiple injections in the operating diagram. One is obviously to combine the primary injectants as one multiple injectant with its own stoichiometric formula (and associated heat term) (Hz)am (O)bm (C)cm(Z)e~
qym
its own rate of injectionjm (moles/mole Fe), and its own
D.M. KUNDRAT, Senior Staff Engineer and Adjunct Professor, is with Armco, Inc., Middletown, OH 45043, and the Department of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45221, respectively. A. RIST, Professor and Director, is with the Laboratory for the Elaboration of Materials, L'Ecole Centrale des Arts et Manufactures, 92295 Chatenay-Malabry CEDEX, France. Manuscript submitted January 2, 1991. METALLURGICAL TRANSACTIONS B
set of pivots Ira, Jr,, Kin, and Lm. The other method is to retain in the operating diagram the separate identities of all the primary injectants, with their own stoichiometric formulae (and associated heat terms) (H2)ap (O)bp (C)~ (Z)~ q# their own rates of injectionjp (moles/mole Fe), and their own sets of pivots Ip, Jp, Kp, and Lp (the subscripts p varying from 1 to n primary injectants). This second method clearly requires that the abscissae for the multiple injectant Xim, Xjm, XK., and XL,,, be formulated in terms of the corresponding abscissae Xip, Xjp, XK,, and XL~, the stoichiometric and thermal coefficients ap, bp, Cp, and qj~, and the injection rates jp for the primary injectants. The amount and the characteristics of an injection are conveniently separated for analysis in the operating dia
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