Blast furnace (BF) remains the dominant ironmaking process worldwide. Central coke charging (CCC) operation is a promising technology for stabilizing BF operations, but it needs reliable and quantified process design and control. In this work, a multi-fluid BF model is further developed for quantitatively investigating flow-thermal-chemical phenomena of a BF under CCC operation. This model features the respective chemical reactions in the respective coke and ore layers, and a specific sub-model of layer profile for the burden structure for the CCC operation. The simulation results confirm that the gas flow patterns and cohesive zone's shape and location under the CCC operation are quite different from the non-CCC operation. Under the CCC operation, the heat is overloaded at the furnace center while the reduction load is much heavier at the periphery regions; the profiles of top gas temperature and gas utilization show bell-shape and inverse-bell-shape patterns, respectively. More importantly, these differences are characterized quantitatively. In this given case, when the CCC opening radius at the throat is 0.35 m, the cohesive zone top opening radius is around 0.50 m, and the isotherms of CCC operation become much steeper (~80 deg) than those of non-CCC operation (~60 deg) near BF central regions. In addition, it is confirmed that carbon solution-loss reaction rate can be decreased significantly at BF central regions under CCC operation. The model helps to understand CCC operation and provides a cost-effective method for optimizing BF practice.
A carbon
composite briquette (CCB), which combines low-rank coal
and iron oxides through agglomeration technology, is one promising
raw material to improve energy efficiency and reduce the fuel rate
for blast furnace (BF) ironmaking. However, the in-furnace behavior
of CCB and its impact on BF performance is not yet clear. In this
study, a computational fluid dynamics model is developed to explore
the in-furnace flow and thermochemical behaviors related to CCB charging
into a BF under full-scale conditions. The model features a submodel
of different chemical reactions in respective coke and ore layers
and an ore–CCB mixture submodel. The results show that, in
comparison to non-CCB operation, the BF with CCB operation can have
higher productivity and a lower coke rate and the top gas temperature
is lower. This is attributed to improved thermal energy utilization
efficiency in CCB operation. Moreover, the carbon mass loss fraction
is compared between coke and CCB, indicating that coke carbon can
be protected by CCB effectively. Then, the detailed reduction behavior
of CCB and ore are analyzed throughout the BF. The thermal reserve
zone temperature is found reduced when CCB is used in the BF. This
model provides an effective tool to evaluate and optimize the BF performance
with CCB charging for future applications.
The oxygen blast furnace (OBF) process has been extensively studied theoretically because of the potentials of promising energy conservation and CO2 emission reduction. Herein, investigations of the OBF process are reviewed and some suggestions for its future development are presented. The main findings can be condensed into the following: static and dynamic models of the OBF should be revised to considering the newest theoretical findings in the thermodynamics and kinetics involved as well as the particular limitations of the technology. Models focusing on energy demand and emissions should be further developed and applied to enhance the design for increased efficiency and sustainability of the complicated OBF system. It will be challenging to operate the full OBF process with top gas recycling (TGR). The development of mathematical models focusing on the practical operation is therefore warranted and would provide useful tools for tackling control problems and difficulties that will arise in forthcoming industrial trials. Considering these potential challenges, a medium oxygen‐enriched blast furnace with TGR as a forerunner is suggested because its operation conditions show greater resemblance with those of the traditional blast furnace. This furthermore provides a path of transition to the use of the full OBF in industrial scale.
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