Convergent-Divergent Injection Lance for the Enhancement of Combustion Efficiency of Pulverized Coal at Blast Furnace

Abstract

To achieve a high rate injection of pulverized coal into a blast furnace, it is so important to increase a combustion efficiency of pulverized coal. Enhancement of particle dispersion is one of the measures to increase combustion efficiency by accelerating oxygen-coal particle mixture in blowpipe to tuyere region. To realize this, it is found that convergent -divergent injection lance designed on the basis of fluid dynamics has superior characteristics. Divergence angle of the lance is optimized as the maximum angle free from the flow separation phenomenon in the boundary layer and convergence angle of the lance is optimized considering the inertia of coal particle in the gas-solid two phase flow. Optimum divergence angle and convergence angle is found to be 7 and 5 degrees respectively. Direct observation results by offline apparatus, hot model experiments and even in the actual blast furnace proves that dispersion of pulverized coal particles is enhanced considerably.It is confirmed that permeability is improved at an actual blast furnace when the developed lances are installed. This result suggests that high combustion efficiency had been achieved by the enhancement of particle dispersibility.It is thought that the convergent -divergent lance can be one of the practical solutions for the stable operation with high rate injection of pulverized coal because the lance can be installed almost all blast furnaces easily by its simple configuration without a large amount of investment.

Effect of Large Amount of Co-injected Gaseous Reducing Agent on Combustibility of Pulverized Coal Analyzed with Non-Contact Measurement

“…There have also been many reports that try to enhance PC dispersibility with adjusting the number, position, and shape of injection lances, to increase PC combustibility. 8,[12][13][14] The mechanical parameters related to the PC dispersibility such as velocity have been measured in other fields with using laser measurement. 15,16) On the other hand, there are some studies analyzing PC dispersibility with numerical methods 8,9) or analysis of photograph of experimental combustion field, 13) but there are few studies in which the mechanical parameters of PC particles are actually measured.…”

Combustion Enhancement of Pulverized Coal with Targeted Oxygen-Enrichment in an Ironmaking Blast Furnace

“…Du et al [14,18] investigated the effect of lance configurations on coal combustion using the CFD method. The reliability and superiority of CFD in understanding pulverized coal combustion have been fully proven [10,[18][19][20][21].…”