Discussion on chemical energy utilisation of reducing gas in reduction shaft furnace

B. N. Liu, Q. Li, Z. S. Zou, A. B. Yu

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9 Citations (Scopus)

Abstract

The reduction shaft furnace is a countercurrent moving bed cylindrical reactor in which hematite pellets are reduced by a gas mixture of H2and CO. Most of the reduction shaft furnaces use hydrogen rich gas as reducing gas. The materials and heat balances show that the heat balance determines the gas consumption. Compared with the gas requirement by reduction reaction, a much greater quantity of gas has to be blown into the furnace to satisfy the heat balance, leading to a high energy consumption and high excess of reduction potential of top gas. To solve this problem, a new approach is proposed where some oxygen is blown into the upper zone of the shaft furnace. As the feasibility study of such an approach, a static model was developed first to calculate input gas flowrate and oxygen rate. Then, based on conservations of mass and heat, a kineticmodel for a typical MIDREX shaft furnace was developed to investigate the proper position for oxygen blowing. The model predictions were validated by comparison with production data. Finally, a kinetic model was developed to investigate the process of shaft furnace with oxygen blowing. The results show that the gas consumption can be reduced from 1897 to 1405 N m3tDRI2-1with oxygen blowing of 20.3 N m3tDRI2-1. After oxygen blowing, the temperature increases sharply, the concentration of CO and H2decreases, and reduction potential of top gas decreases from 1.48 to 0.69, showing that the gas utilisation is greatly improved. These models can be used for process optimisation development.

Original languageEnglish
Pages (from-to)568-574
Number of pages7
JournalIronmaking and Steelmaking
Volume41
Issue number8
DOIs
Publication statusPublished - 1 Sep 2014
Externally publishedYes

Keywords

  • Chemical energy
  • Oxygen injection
  • Reducing gas
  • Reduction shaft furnace

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