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Conservation equations of mass and momentum are solved numerically in an actual plant size hearth to determine the wall shear stress at various operating conditions. The effect of different coke-bed shape and position was studied on the wall shear stress of the hearth. It was found that there exists an optimum cokefree space volume for all kinds of coke-bed shapes with respect to shear stresses on the sidewall as well as on the hearth bottom. It was found that conical coke-bed with a sitting position could induce more wall shear stress on the side wall if the coke-free space volume was limited to about 48 m 3 and if the free space increased beyond 48 m 3 then the spherical coke-bed in a floating condition induced maximum stress on the wall where as all other coke-bed shapes studied were benign to the stress on the wall. Conical coke-bed shape is more vulnerable, in terms of producing more stress on the hearth bottom than any other shapes.

The injection rate of fossil fuels in the blast furnace is limited because of a drop in the flame temperature in the raceway as well as problems in deadman region and the cohesive zone owing to the unburnt char. An alternative option for coke saving, a clean deadman as well as increase in blast furnace productivity is injection of hot reducing gases (HRG) which are produced by low grade coal gasification or top gas recycling after CO 2 and N 2 removal. Calculations using a mathematical model show that HRG injection at higher temperature is desirable. Hot reducing gas injection is possible up to 300 Nm 3 thm 21 , above which the top gas temperature shoots up beyond practical limits. Furthermore, it also shows that if the flame temperature is maintained constant by varying steam and oxygen injection, the productivity is increased by 16% and coke rate is reduced by 84 kg thm 21 with the replacement ratio of 1?4 kg coke/kg gasified coal at 300 Nm 3 /thm of HRG injection. It was also observed that the complete replacement of pulverised coal (PC) injection with HRG injection is more effective over the coinjection of PC and HRG in terms of coke rate saving. However, oxygen enrichment is possible up to 75% with the coinjection of HRG and PC, with a resultant of rise in productivity. Injection of HRG in the form of top gas (blast furnace gas) is more effective over the injection of HRG generated from coal gasification. The productivity is increased by 25% and coke rate is reduced by 83 kg thm 21 with the replacement ratio of 1?7 kg coke/kg HRG at 250 Nm 3 thm 21 of HRG injected from top gas. List of symbolsHRG hot reducing gas PC pulverised coal PCI pulverised coal injection RAFT raceway adiabatic flame temperature TRZ thermal reserve zone TGT top gas temperature Flame temperatureBy injecting auxiliary fuels, flame temperature is reduced since the bosh gas volume rises more strongly than the Research and Development,

Any improvement in Blast Furnace productivity under a given set of operating conditions is fundamentally related to better flow distribution of gas through layered burden structure in Blast Furnace. Flow distribution and hence pressure drop of gas in granular zone of blast furnace is dependent on number and thickness of alternating layers of coke and metallic burden. A significant part of this total pressure drop in granular zone can be attributed to interfacial resistance between two successive layers. Whereas, pressure drop in porous layers of materials can be described by well known Ergun's equation in terms of all physical parameters, interface resistance needs specific treatment. Systematic study to investigate the effect of interfacial resistance on gas flow between two successive layers of different material has been attempted in this work.Laboratory scale experiments in scale down model of blast furnace were conducted to establish and quantify interface resistance for different layer configurations.

Stable blast furnace operation requires proper drainage of liquid from the hearth. The estimation of drainage rate and hearth liquid level are of utmost importance for understanding the underlying hearth phenomena. The present review gives an insight of the need for measurement of the hearth liquid level and further throws light on various methods of estimation of hearth liquid level in-depth, which is primarily divided into 2 categories namely; model-based estimation and sensor-based estimation. Although the model-based estimation and sensor-based estimation have their own advantages and disadvantages, an integrated system comprising of both methods could potentially facilitate operators to reveal the state of hearth, which is unless not available with the implementation of a single method of estimation. Furthermore, the challenges in the estimation and the prospects for determining the reliable hearth liquid level measurement in blast furnace are discussed. The article is presented to give prospect of encountering the drift occurring in estimation of liquid level, which leads to inaccurate prediction and simulation with the industrial blast furnace. Lastly, the article gives recommendation for improving the liquid level estimation methods in blast furnace.