Abstract
The objective of the article is to investigate analytically the alternations in reduction processes indices in a blast furnace at partial replacement of coke with powder coal. To compensate the reduced gas permeability of the charge materials column at powder coal injection the share of direct mixed supplies in charging cycles was decreased. The performed comparison revealed that the indices of reduction processes in the investigated periods turned out to be close enough. It was found out that in the period before repairs the thermal losses of the furnace were actually 2% higher before PC injection process implementation. The overall coefficient of coke replacement with coal powder did not reach the value of 1 kg/PCkg. The furnace operation indices before and after powder coal injection into the furnace hearth with equal thermal losses have been determined. The comparison revealed the worsening of reduction processes indices at powder coal injection into the furnace hearth as well as the possibility to reduce the specific coke consumption due to improvement in gas flow reducing operation. By means of graphical and analytical diagram of the blast furnace process all the alternations of melting indices have been analyzed with regard to the gas composition approximation within the area of decelerated thermal exchange to equilibrium condition, judging by reaction of iron monoxide reduction by gases before and after powder coal injection into the furnace hearth. The minimal theoretically possible degrees of direct reduction, according to M.A. Pavlov as well as the consumption of coke, solid fuel and the reducing gas have been determined. The analyzed operation modes have been comparatively studied, as well as the degrees of gas utilization, the complex index of reduction processes, the criterion of completeness of indirect reduction reactions and indices of the melting ideality. The usefulness of determination of the degree of melting ideality according to the overall consumption of solid fuel has been shown
Highlights
Проведено сравнение показателей восстановительных процессов доменной плавки при переходе на технологию вдувания пылеугольного топлива
The performed comparison revealed that the indices of reduction processes in the investigated periods turned out to be close enough
The comparison revealed the worsening of reduction processes indices at powder coal injection into the furnace hearth as well as the possibility to reduce the specific coke consumption due to improvement in gas flow reducing operation
Summary
Проведено сравнение показателей восстановительных процессов доменной плавки при переходе на технологию вдувания пылеугольного топлива. В результаті їх порівняння виявлено погіршення показників відновлювальних процесів при вдуванні до горну печі ПВП, а також наявність резерву зниження питомої витрати коксу за рахунок поліпшення відновлювальної роботи газового потоку. Проведено порівняння для розглянутих режимів роботи печі ступенів використання газу, комплексного показника відновлювальних процесів, критерію повноти протікання реакцій непрямого відновлення і показника ідеальності плавки. The comparison revealed the worsening of reduction processes indices at powder coal injection into the furnace hearth as well as the possibility to reduce the specific coke consumption due to improvement in gas flow reducing operation. By means of graphical and analytical diagram of the blast furnace process all the alternations of melting indices have been analyzed with regard to the gas composition approximation within the area of decelerated thermal exchange to equilibrium condition, judging by reaction of iron monoxide reduction by gases before and after powder coal injection into the furnace hearth.
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