Abstract
Abstract Pulverized coal injection (PCI) into blast furnace tuyeres is widely used by integrated steel mills worldwide to reduce the consumption of coke and costs. High injection rates are desirable. The big challenge is to achieve them with cheaper and lower quality raw materials, without losing the quality of the hot metal and the productivity of the blast furnace. An increase in the injection rate leads to improved fuel selection. Thus, it is important to have knowledge of the injected fuel quality variables that affect the burning efficiency and the replacement rate of the coke into the furnace, as well as the quality of the hot metal and the stability of the furnace. In this context, the present study is based on the chemical characterization and combustibility behavior of four fuels: Australian coal (CMA), North-American coal (CMN), charcoal fines (MCV) and green petroleum coke (CVP) and fuel blends. Results of chemical analysis show that the CMA, CMN, MVC and CVP are within the ranges of acceptable values in the PCI process for the ash and sulfur contents. The order of combustibility by thermogravimetric analysis was MCV>CMN>CMA>CVP. However, the combustion rate obtained by the simulator test, performed under extreme conditions of short residence time and high temperature, presented a different order of combustion rate of MCV>CVP>CMA>CMN, which may be related to the mineral on char. The blend that presented the best burning efficiency was obtained for the composition containing 20%MCV+80%CVP, followed by blends containing 80 and 90% of CMA, respectively.
Highlights
Pulverized coal injection (PCI) is an effective technology for reducing coke consumption in the blast furnace (BF) (Bennett and Fukushima, 2003; Lion et al, 2017; Zou et al, 2017), leading to a reduction in BF operational costs, which is explained by the fact that the price of coal is slightly lower than that of coke
The results of Thermogravimetric Analysis (TGA)/derivative of the weight loss curve (DTG)/difference in the thermal analyses (DTA) analysis are presented in Figure 2 a-d, The TG/DTG/DTA curves were determined for the single fuel samples versus temperature
Through the combustion rate results, it is observed that the addition of charcoal fines in the coal mixture contributed to a better combustibility
Summary
Pulverized coal injection (PCI) is an effective technology for reducing coke consumption in the blast furnace (BF) (Bennett and Fukushima, 2003; Lion et al, 2017; Zou et al, 2017), leading to a reduction in BF operational costs, which is explained by the fact that the price of coal is slightly lower than that of coke. It is possible to consider among the advantages of the use of charcoal for injection, the low sulfur and phosphorus content, high combustibility and relatively low ash content. Another possibility is green petroleum coke or pit coke, a byproduct of petroleum refining. Its high carbon content and calorific power, low ash and sulfur content, relative low cost and abundance have made it an attractive product for industrial use, being suitable for consumption in blast furnace replacing metallurgical coke for its use in blends for PCI purpose (Silva, 2010). This study aims to investigate coal, charcoal and green petroleum coke combustibility and to identify the characteristics that justify such behavior
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