Companhia Siderúrgica Nacional (CSN), Volta Redonda, Brazil:

R. S. N. Motta, Senior Engineer of Development of Production

P. A. da Silva Oliveira, Engineer

E-mail (общий): nadur@csn.com.br

Universidade Federal de Engenharia de Itajuba (UNIFEI):

L. E. de Souza, Professor, Head of Thesis Project

Two methods for coal flow measurement (load cells and algorithm ΔW) are described in this article for a pulverized coal injection (PCI) process into the blast furnace No. 3 and pulverized coal injection plant at Companhia Siderúrgica Nacional (CSN) in Brazil. Overview of this PCI plant is shown. The original design is based on vessel weight variation through time and on a moving average calculation. Batch integration was carried out before and after the coal filling phase of the vessels. Coal flow measurement error during measuring by load cells is analyzed. Start and end of injection phase are displayed. It is demonstrated, both mathematically and by comparison of these two methods, that the measurement for pulverized coalbased on the original design is affected in about 2.5 % due the replacement of coal by nitrogen during the injectionphase. Three hypotheses of origination of this error are comparatively discussed. Therefore, the estimated margin of error of the coal mass balance in the PCI plant increases from 2 to 3 %. This margin of error is in accordance with the result of a 3 % average obtained by testing. These are the main causes of the non-closing of the mineral coal mass balance. As a result, the blast furnace fuel rate and the measurement for pulverized coal flow must be corrected by afactor to overcome this continuous error if the original method is applied. Integrated results for two measuring techniques are presented and adopted solution for injected coal integration in the blast furnace is concluded.

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7. Motta, R. S. N.; de Souza, L. E.; Birk, W.: Advanced dynamic models for a pulverized coal injection plant, Proc. 4. Internat. Conf. on Modelling and Simulation of Metallurgical Processes in Steelmaking (Steelsim 2011) at Metec InSteelCon 2011, 30 June 2011, Dusseldorf, Germany.