Masanori Tokuda

The transfer of silicon from the gas phase to molten iron in the blast furnace

The mechanism of silicon transfer in a blast furnace has been studied. It is concluded that the contribution of slag-metal reaction to silicon increase in the metal will not be very important because of the slow rate of the reaction and high oxygen potential of slag in a blast furnace. By making use of kinetic and thermodynamic data, it is shown that the reaction of SiO containing gas with liquid iron of high carbon content takes an important role in the silicon transfer in a blast furnace.

Ignition and combustion of laser-heated pulverized coal

The temperature change in coal and graphite during heating and combustion by a CO2 laser heat source was measured using the multi-two-colour method. Laser intensity ranging up to 3.0 W mm−2 at 10.6 μm wavelength was used. The behaviour of heating particles was observed with a stereomicroscope. Graphite particles and several types of coal were used to cover the range of volatile matter from 0 to 43.3 wt%. Experiments were performed to study the influence of volatile matter, particle diameter, oxygen content in the atmosphere and laser intensity on each type of carbon particle. Volatile matter affected the initial heating stage and the ignition stage. Particle diameter had no observable effect at any stage. Laser input intensity mainly affected the heating-up in the initial stage. An increase in oxygen content gave a high heating rate in the ignition stage and raised the temperature in sustained combustion.

Mixing characteristics of a submerged jet measured using an isokinetic sampling probe

The flow properties and mixing characteristics of a submerged gas jet near the injection point were measured using an isokinetic sampling probe in a water model. The radial and axial profiles of gas velocity, water velocity, and void fraction were measured. Since the gas velocity was always larger than that of the water, the existence of a slip velocity between gas and water was confirmed. A one-dimensional mathematical model was developed using the dimensionless slip velocity as a parameter. The dimensionless slip velocity (S) was estimated to be 0.3 to 0.6 for the nitrogen-water system. TheS of the He-water system was slightly larger than that of the nitrogen-water system. When the model was applied to calculate the gas fraction in the jet for the nitrogen-mercury system,S was estimated to be 0.95 to 0.97. A large slip velocity between gas and liquid is expected for gas-metal systems.

Coupling phenomena in the transfer of elements between a gas phase and iron melts

The simultaneous transfer of Si and C from a gas phase containing SiO and CO to liquid Fe-C alloys has been investigated. It was found that, although the silicon content of the melt increased with time as expected, the carbon content initially decreased, in spite of the fact that the carbon potential of the gas phase was above that of the liquid alloy. These phenomena are interpreted in terms of irreversible thermodynamics which shows that the overall transfer reactions are comprised of coupled reactions: SiO(g) + CO(g) →Si + CO2(g) andC + CO2(g) → 2CO(g). It is also shown that the simultaneous transfer of carbon and oxygen from gas mixtures of CO and CO2 to liquid iron occurs via the coupled reactions CO2(g) →O + CO(g) and 2CO(g) →C + CO2. In each case there is a predominant, or driving reaction which promotes the other.

Data processing of spectral radiation for temperature measurement

Abstract This study describes the temperature determination method with sufficient accuracy even in the case that the emissivity of surface is significantiy dependent on the wavelength.