A numerical simulation was performed to study the flow pattern,mixing time and open-eye slag produced by argon gas injection in an industrial scale steel ladle under non-isothermal conditions.The liquid steel remains ...A numerical simulation was performed to study the flow pattern,mixing time and open-eye slag produced by argon gas injection in an industrial scale steel ladle under non-isothermal conditions.The liquid steel remains 5min before the injection,and thermal stratification and convective flows were analyzed.Three different sequences in stages employing various argon-gas flow rates were simulated.In the first case,a sequence with the highest flow rates of argon was applied,while in the second and the third sequences,the intermediate and the lowest flow rates of argon gas were used,respectively.For determining the chemistry homogenization,the mixing time was computed and analyzed in all three cases.It was found that the cold steel is located near the walls while the steel with a high temperature is accumulated in the center of the ladle above the argon-gas tuyere.The higher and lower flows promote a faster chemistry homogenization owing to the secondary recirculations that are developed closer to the walls.The results from steel temperature drop show a good concordance with plant trial measurements.展开更多
The laser surface remelting (LSR) treatment was performed to Al-2.0 wt% Fe alloy with a 2 kW Yb-fiber laser (IPG YLR-2000S). The substrate and laser-treated material characterization were executed using different tech...The laser surface remelting (LSR) treatment was performed to Al-2.0 wt% Fe alloy with a 2 kW Yb-fiber laser (IPG YLR-2000S). The substrate and laser-treated material characterization were executed using different techniques. Among them, the microstructure was analyzed by optical microscope, SEM, low-angle X-ray diffraction (LAXRD) and the corrosion test was made in aerated solution of 0.1 M H2SO4 at a temperature of 25°C ± 0.5°C. As result was shown, the micrograph of LSR-treated material displaying can be a fine cellular structure and the existence of certain nano-porosities and a similar to a nano-dendritic growth was observed too. The characteristic of melted zone was constituted of metastable phases according to the result of x-rays and the behavior corrosion as a result of the LSR-treated sample, which it was shown to be more resistant to corrosion than the untreated sample. A comparative study was carried out of the cyclic polarization of the laser-treated and untreated samples, demonstrating that the reduction and oxidation reverse peaks were not observed and being the cyclic polarization behavior was of irreversible character in both samples, however, the LSR-treated sample propitious the passivity on the surface also reduced the corrosion phenomena. Wherefore, this type of laser-treated alloy can be applied in the aerospace, aeronautic and automobilist industries.展开更多
Biodiesel bioremediation in soils may occur by natural attenuation or by engineered techniques, such as biostimulation and bioaugmentation. The present study evaluated the degradation of biodiesel in two soils with di...Biodiesel bioremediation in soils may occur by natural attenuation or by engineered techniques, such as biostimulation and bioaugmentation. The present study evaluated the degradation of biodiesel in two soils with different particle size characteristics by the bioremediation processes of natural attenuation and biostimulation. The experiment was carried out ex situ, with the factors temperature, moisture content, and pH being controlled for the experimental period of 110 days. The study aimed at evaluating the biodegradation of a clayey soil （A） and a sandy soil （B）, both contaminated with pure biodiesel, by using the analytical methods of respirometry and gas chromatography. Biostimulation treatments using nitrogen, phosphorus, and potassium solutions （NPK） promoted higher microbiological activity in both soils. At the end of the experiment, it was observed that biostimulation was more efficient when compared to natural attenuation, showing higher biodiesel degradation for both soils A （59.76%） and B （90.41%）.展开更多
文摘A numerical simulation was performed to study the flow pattern,mixing time and open-eye slag produced by argon gas injection in an industrial scale steel ladle under non-isothermal conditions.The liquid steel remains 5min before the injection,and thermal stratification and convective flows were analyzed.Three different sequences in stages employing various argon-gas flow rates were simulated.In the first case,a sequence with the highest flow rates of argon was applied,while in the second and the third sequences,the intermediate and the lowest flow rates of argon gas were used,respectively.For determining the chemistry homogenization,the mixing time was computed and analyzed in all three cases.It was found that the cold steel is located near the walls while the steel with a high temperature is accumulated in the center of the ladle above the argon-gas tuyere.The higher and lower flows promote a faster chemistry homogenization owing to the secondary recirculations that are developed closer to the walls.The results from steel temperature drop show a good concordance with plant trial measurements.
文摘The laser surface remelting (LSR) treatment was performed to Al-2.0 wt% Fe alloy with a 2 kW Yb-fiber laser (IPG YLR-2000S). The substrate and laser-treated material characterization were executed using different techniques. Among them, the microstructure was analyzed by optical microscope, SEM, low-angle X-ray diffraction (LAXRD) and the corrosion test was made in aerated solution of 0.1 M H2SO4 at a temperature of 25°C ± 0.5°C. As result was shown, the micrograph of LSR-treated material displaying can be a fine cellular structure and the existence of certain nano-porosities and a similar to a nano-dendritic growth was observed too. The characteristic of melted zone was constituted of metastable phases according to the result of x-rays and the behavior corrosion as a result of the LSR-treated sample, which it was shown to be more resistant to corrosion than the untreated sample. A comparative study was carried out of the cyclic polarization of the laser-treated and untreated samples, demonstrating that the reduction and oxidation reverse peaks were not observed and being the cyclic polarization behavior was of irreversible character in both samples, however, the LSR-treated sample propitious the passivity on the surface also reduced the corrosion phenomena. Wherefore, this type of laser-treated alloy can be applied in the aerospace, aeronautic and automobilist industries.
文摘Biodiesel bioremediation in soils may occur by natural attenuation or by engineered techniques, such as biostimulation and bioaugmentation. The present study evaluated the degradation of biodiesel in two soils with different particle size characteristics by the bioremediation processes of natural attenuation and biostimulation. The experiment was carried out ex situ, with the factors temperature, moisture content, and pH being controlled for the experimental period of 110 days. The study aimed at evaluating the biodegradation of a clayey soil （A） and a sandy soil （B）, both contaminated with pure biodiesel, by using the analytical methods of respirometry and gas chromatography. Biostimulation treatments using nitrogen, phosphorus, and potassium solutions （NPK） promoted higher microbiological activity in both soils. At the end of the experiment, it was observed that biostimulation was more efficient when compared to natural attenuation, showing higher biodiesel degradation for both soils A （59.76%） and B （90.41%）.
