Combustion Behaviors of Fine Coal and Its Impact on Gas Permeability at Lower Part of Blast Furnace under High Pulverized Coal Rate Operation

Abstract

Practical ways of estimating temperatures of coke flowing into raceway as well as the gas core depth validated by direct measurement were suggested for the purpose of better describing the combustion behaviors of injected coal fine in blast furnace raceway. The numerical simulation model was refurnished with the scheme, and helped clarifying an intriguing effect of coal gasification or decomposition degrees before exiting tuyere tip on attained combustibility of coal at raceway boundary.Another scheme for quantitative expression of pressure losses caused exclusively by coal fine residence in and around raceway was also developed by shutting off coal injection for minutes at practical operation. The obtained results lead to developing the advanced tuyere, CD (converged and diverged) tuyere which enabled reducing the interaction between injectants and hot blast inside tuyere and thus improving overall gas permeability even under conditions of massive coal injection over 250 kg/tHM.

Assessment of midterm CO2 emissions reduction potential in the iron and steel industry: a case of Japan

“…The theoretical maximum for PCI is thought to be 270e290 kg/t-pig iron, depending on the BF type and the strength of coke used (IPPC, 2011;Ribbenhed et al, 2010), but a high PCI rate does not necessarily replace coke effectively. Literature indicates that for existing BFs the coke replacement rate is high at 0.85e0.95 kg coke/kg PCI (IPPC, 2011) for 180e200 kg PCI/t-pig iron, and the replacement rate declines as the PCI increases (IEA, 2007;Nozawa et al, 2011). Nomura and Callcott (2011), the obsolete scrap exports to China may contain considerable amount of copper scrap.…”

Simulation of Powder Motion with Particle Contact Model Including Intervening Liquid

“…[1][2][3] Major reducing agent used in the ironmaking processes is coal, and its usage directly influences the carbon dioxide emission. Thus various research and development approaches to decrease the carbon usage in the blast furnace process, such as control of coke reactivity and close arrangement of iron oxide and carbonaceous materials, [4][5][6][7] utilization of hydrogenous reducing agent, [8][9][10] enhancement of hydrogen reduction, 11,12) and mixed charging of iron bearing and carbonaceous materials 13,14) have been carried out. Lowering the carbon input to blast furnace corresponds to the decrease in the inputs of thermal energy and reducing gas that are the driving forces of the process, thus it is expected that the instability of the process operation arises.…”

Carbon Requirement for Ironmaking under Carbon and Hydrogen Co-existing Atmosphere

“…Thus it is considered that the improvement of the ironmaking processes is a key measure. Various approaches to decrease the carbon usage in the blast furnace, which is the principal process of ironmaking, have been developed, such as the control of reactivity of coke and arrangement of carbonaceous material and iron oxide, [4][5][6][7] the utilization of hydrogen containing reducing agents, [8][9][10] the increasing the hydrogen reduction, 11,12) the coke mixed charging. 13,14) Although each approach needs breakthroughs in individual aspects, the target of the all process is the theoretical minimum of the carbon consumption.…”

“…In other words, the analysis was made under no hydrogen condition. In the actual operation, the hydrogen participates in the reduction of iron oxides in the processes, and some projects [8][9][10][11][12] aim to increase the contribution of hydrogen to decrease the CO 2 emission. Calderon 17) developed a method to estimate the carbon consumption in blast furnace process.…”