共查询到20条相似文献,搜索用时 31 毫秒
1.
Manabu Iguchi Olusegun J. Ilegbusi Hiroshi Ueda Tomoaki Kuranaga Zen-Ichiro Morita 《Metallurgical and Materials Transactions B》1996,27(1):35-41
Water model experiments were performed to study the effect of top slag on the mean flow and turbulence characteristics in a steel bath agitated by bottom gas injection. The slag was modeled by silicone oil with a density of 0.968 g/cm3 and a kinematic viscosity 100 times larger than that of water at 25 °C. Velocity measurements were made using a two-dimensional (2-D) laser Doppler velocimeter (LDV) in the absence of swirl motions. The output signals of the LDV system were processed on a personal computer to obtain the axial and radial mean velocity components, the root-mean-square (rms) values of the axial and radial turbulence fluctuations, the Reynolds shear stress, and the turbulence production for two cases with and without top slag. The bubbling jet (or the bubble dispersion) region was localized near the centerline of the bath by the presence of the top oil layer. The mean flow and turbulence motions in the recirculation region located outside the bubbling jet region were also suppressed significantly by the top layer. This result could be attributed to the entrainment of top slag into steel in a real system. 相似文献
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采用水力学模型试验方法研究了不同底吹孔位置、不同底吹气量、不同顶渣厚度和粘度时对钢液混匀时间的影响.结果表明:结合此实验条件,钢包的单点偏心喷吹位置距钢包底约1/3半径处为宜;随着底吹气量的增大,均混时间明显缩短;渣层越厚,均混时间越长,渣层粘度对均混时间的影响不是很明显,但总的来说,渣层粘度越大,均混时间越长. 相似文献
4.
An experimental study has been performed to investigate the bath mixing intensity induced by a high-strength submerged gas
injection in a bottom blown air-stirred one-seventh water model of Creusot-Loire Uddeholm (CLU) reactor using three different
tuyere configurations. Experimental results have been discussed in terms of the mass transfer rate and mixing time. The air
flow rates varied from 0.00599 to 0.01465 m3/s. The mixing time was determined at various gas flow rates, bath heights, and nozzle orientations, both in the presence
and absence of a second phase. The mixing time was found to decrease with increasing gas flow rate and decreasing bath height.
The influence of bath mixing intensity on mass transfer between metal (water) and slag (paraffin) was studied by measuring
the transfer of benzoic acid from the gas-stirred water bath to paraffin as a function of the gas injection parameters. The
bath mixing intensity was characterized by the value of the mass transfer rate constant. The rate constant of mass transfer
between the metal and slag was found to increase with increasing gas injection rate and decreasing bath height. 相似文献
5.
为研究钢渣界面卷渣现象,采用水力学模拟实验,对底吹条件下卷渣过程进行了分解,对油滴形成原因及形成过程进行阐述.并通过改变油厚、黏度进行了实验,研究其对渣滴的影响,发现临界卷渣吹气流量与炉渣黏度之间近似满足y=0.00165x+0.72581的线性关系.且对于同一黏度条件,随着吹气流量的增大,生成油滴的最小直径逐渐减小;而对于不同黏度,随着硅油黏度的逐渐增大,生成的最大、最小油滴直径逐渐增大.而随着油层厚度的增加,临界卷渣气量呈y=1.2-0.2x的线性规律下降. 相似文献
6.
Manabu Iguchi Tadatoshi Nakatani Hiroshi Ueda 《Metallurgical and Materials Transactions B》1997,28(1):87-94
Water model experiments were carried out to study the effect of top slag on the turbulence structure in a molten steel bath
agitated by bottom gas injection. Water and silicone oil were used as models of molten steel and slag, respectively. Air was
injected through a single-hole bottom nozzle so that the reverse emulsification of the silicone oil occurred at the silicone
oil-water interface. Silicone oil droplets thus generated were carried deeply into the lower water layer. Turbulence measurements
were made using a two-channel laser Doppler velocimeter (LDV) in the presence and absence of the top oil layer. A conditional
sampling method called the four-quadrant classification method was applied to detect large scale coherent motions in the vertical
bubbling jet as well as in the recirculation region. The structure and intensity of turbulence inside the bubbling jet were
strongly affected by bubbles. In the absence of the top oil layer, higher momentum fluid motions directed from the centerline
of the bubbling jet to the sidewall of the vessel were mainly responsible for the turbulence production in the bubbling jet,
while lower momentum fluid motions directed from the sidewall toward the centerline governed the turbulence production in
the recirculation region. On the other hand, in the presence of the top oil layer, the coherent motion in the bubbling jet
was also affected slightly by the top layer except for the center of the bubbling jet, whereas any distinguished coherent
motion was not observed in the recirculation region, and hence, turbulence production was weak there. 相似文献
7.
Several of the metallurgical reactions occurring in gas stirred steel ladles are controlled by liquid phase mass transfer
between the metal and slag. In order to calculate the rate of these reactions, information about the two phase mass transfer
parameter is necessary. The mass transfer between two immiscible liquids, oil and water simulating slag and steel, respectively,
was measured in a scale model of a ladle. The mass transferred species was thymol which has an equilibrium partition ratio
between oil and water similar to that for sulfur between slag and metal. The mass transfer rate was measured as a function
of gas flow rate, tuyere position and size, method of injection, oil viscosity, and oil/water volume ratio. In addition, mixing
times in the presence of the oil layer and mass transfer coefficient for the dissolution of solid benzoic acid rods were measured.
The results show that there are three gas flow rate regimes in which the dependence of mass transfer on gas flow rate is different.
At a critical gas flow rate, the oil layer breaks into droplets which are entrained into the water, resulting in an increase
in the two phase interfacial area. This critical gas flow rate was found to be a function of tuyere position, oil volume,
densities of two phases, and interfacial tension. Two phase mass transfer for a lance and a tuyere was found to be the same
for the same stirring energy in low energy regions regardless of lance depth. Mass transfer is faster for a center tuyere
as compared to an offcenter tuyere, but mixing times are smaller for the offcenter tuyere. From the results obtained, the
optimum stirring conditions for metallurgical reactions are qualitatively discussed.
SEON-HYO Kim, formerly Graduate Student in the Department of Metallurgical Engineering and Materials Science, Carnegie Mellon
University. 相似文献
8.
钢包卷渣临界底吹流量规律的水力学模拟研究 总被引:1,自引:0,他引:1
用水模拟钢水、油模拟钢渣,通过水力模型研究了底吹钢包中的临界卷渣流量.结果表明,临界卷渣流量随渣层厚度的增加而减小,随粘度的增加而增大,通过分析渣-钢界面的速度分布和能量平衡,对以临界流量作为卷渣发生的判定条件的准确性进行了检验.采用因次分析得到了底吹钢包临界卷渣流量的无因次表达式Qcr∝(Δρσ/ρ2s)0.35(μs/μm)0.3(Hs/Hm)-0.42,利用该表达式计算了实际钢包卷渣的临界流量,分析了影响因素,建议110 t钢包进行钢水弱搅拌净化操作时最大底吹流量为QN=240 L/min. 相似文献
9.
In refining processes such as the AOD process cold gas is blown horizontally into the molten metal bath of the processes. The spatial distribution of bubbles in the bath is one of the important factors influencing the efficiency of the processes. In this study, a water model study was carried out to understand the characteristics of bubbles and liquid flow generated by horizontal gas injection. The bubble and liquid flow characteristics were measured using an electro‐resistivity probe and a laser Doppler velocimeter, respectively. In the flow field near the nozzle the bubble characteristics for the horizontal cold gas injection can be predicted by empirical equations derived for isothermal gas injection systems. The liquid flow characteristics could not be measured in this region. On the other hand, in the region far from the nozzle the two characteristics for the cold gas injection became different from those for the isothermal gas injection because of enhanced buoyancy force acting on expanding cold bubbles due to heat transfer. 相似文献
10.
AbstractThe fluid flow and mixing characteristics in the bath during the argon–oxygen decarburisation (AOD) process have been investigated on a water model of an 18 t AOD vessel blown through two annular tube type lances of constant cross-sectional area. The geometric similarity ratio between the model and its prototype (including the lances) was 1 : 3. Based on theoretical calculations of the parameters of the gas streams in the lances, the gas blowing rates used for the model were determined fairly precisely. Thus, sufficiently full kinematic similarity between the model and its prototype was ensured. The influence of the gas flowrate and the angle included between the two lances was examined. The results demonstrated that the liquid in the bath underwent vigorous circulatory motion during blowing, and there was no obvious dead zone in the bath, resulting in excellent mixing and a short mixing time. The gas flowrates, particularly that of the main lance, had a key influence on these characteristics. However, the gas jet of the sublance had a physical shielding effect on the gas jet of the main lance, and mixing efficiency could be improved by a suitable increase in the gas blowing rate of the sublance. The angular separation of the two lances also had a marked influence on the flow and mixing in the bath. An excessively large or small separation of the two lances would reduce the stability of blowing and would also be unfavourable to mixing. The optimum range of separation is 60–100° under the conditions of the present work. The relationships between the mixing time and the gas blowing rate, the stirring energy, the modified Froude numbers for the main lance and sublance, the lance arrangement, etc. have been obtained. 相似文献
11.
Liangcai Zhong Xiaobin Zhou Peng Jiang Hongliang Wang Lipeng Pang Peifeng Hao 《钢铁冶炼》2013,40(5):431-442
The effects of gas bubbling with double bottom porous beams on the flow during the filling process at different filling levels in a large ingot mould were investigated. Mixing time is long in the mould without gas bubbling. In the case of bottom gas bubbling with a small gas flow rate, the mixing time can be decreased by about 50–70%. Favourable bubbling position is 102–142?mm from the bottom centre. Large granular slag drops are entrapped at a lower filling level less than 60?mm and the slag drops entrapped become small with an increase in filling height without gas bubbling. Gas bubbling with reasonable flow rates does not cause strong slag entrapment during the initial stage of the filling process. Bottom gas bubbling in filling process of large ingot casting is beneficial to achieve simultaneously uniform temperature and composition, and to remove inclusions in the bath. 相似文献
12.
Manabu Iguchi Ryoji Tsujino Kei-Ichi Nakamura Mitsuhiro Sano 《Metallurgical and Materials Transactions B》1999,30(4):631-637
The intensity of mixing in a molten metal bath stirred by bottom gas injection can be represented by the mixing time. According
to previous water model experiments, the mixing time is known to be dependent on the operational variables such as the bath
diameter, bath depth, location of a bottom nozzle, and gas flow rate. It is not easy to control the former three variables
during processing, and the dependence of the mixing time on the gas flow rate is weak. In this study, the possibility of changing
the mixing time drastically due to the control of the surface flow in the bath is examined. Three kinds of boundary conditions
were imposed on the bath surface, and the relation between the fluid flow phenomena resulting from the surface flow control
and the mixing time was investigated. The mixing time was found to be significantly influenced by the surface flow control.
In particular, when the surface flow was suppressed by bringing a circular cylinder into contact with the bath surface, the
mixing time became very long. 相似文献
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为了考察复吹转炉底吹氧气和石灰粉过程中的熔池特性,建立复吹转炉底吹喷石灰粉的水模型,用水模拟铁水,用空心玻璃微珠模拟石灰粉。利用图像处理法研究了底吹氧气和石灰粉时粉剂分布情况及熔池搅拌情况。采用熔池电导率法考察了相同条件下底吹喷粉与不喷粉时的混匀时间。研究结果表明,喷粉能够促进熔池搅拌,且粉剂扩散速度随底吹载气流量增大而增大;未喷粉时,混匀时间随载气流量增大而减小;在相同底吹载气流量条件下,喷粉时熔池的混匀时间明显低于未喷粉时的混匀时间,且在试验范围内,混匀时间在底吹载气流量为2 m3/h(标准态)时出现极小值。 相似文献
15.
Model study of mixing and mass transfer rates of slag-metal in top and bottom blown converters 总被引:2,自引:0,他引:2
Water model experiments have been conducted to clarify mixing rates of molten steel and mass transfer rates between slag and
metal in LD and Q-BOP furnaces using six different circular tuyere arrangements. Splashing and ‘spitting’ were also examined
with a view to finding a quiet bath with minimum mixing time and maximum mass transfer rate. Froude’s similarity criterion
was fulfilled to determine gas flow rate and bath depth. Complete mixing time of water determined by tracer technique had
been 0.9 second to 1.8 seconds for Q-BOP as compared to 6 seconds to 13 seconds for LD. This shows that the stirring intensity
in Q-BOP is remarkably larger than that of LD. A simple relationship τ = 5.9(Q/N)
−0.49 was obtained with gas flow rateQ and number of tuyereN. This indicates that flow rate of gas per tuyere should be intensified to realize better mixing. Mass transfer coefficient
KBa for bottom blowing was found to be almost double that for top blowing. Of all the tuyere configurations studied for Q-BOP’s,
a half circular tuyere arrangement was found to be the best considering all aspects of mixing, mass transfer, and bath agitation. 相似文献
16.
The formation of slag eye in a gas stirred ladle was studied through cold models and industrial trials.In the cold model,water and sodium tungstate solution were employed to simulate liquid steel,and silicon oil was employed to simulate slag.The simulation results revealed that the gas flow rate and bath height had strong effects on the slag eye size.In particular,the thickness of slag layer played a strong role in the slag eye size.In addition,the slag eye could not be formed when the thickness of the top layer was more than 4 cm in water-silicone oil model.Besides,the section area of vessel had a great impact on the slag eye size.Industrial trials results showed a similar trend that the gas flow rate was very significant on the slag eye size.The predictions of the existing models showed larger predictions deviations compared with the experimental data.Moreover,a new model without fitting parameters was developed based on force balance and mathematical derivation,and verified by the experimental data.The new model provides the prediction with small deviations by comparing with the data acquired from cold models and industrial trials. 相似文献
17.
An impinging gas jet on a molten bath having a slag layer on top is encountered in various metal processing operations. The
impinging region was studied using a physical model consisting of an air jet and water bath. Kerosene and corn oil were used
as the second layer to investigate the role of the slag layer properties on interface shape and bath circulation. The interface
shapes were measured both photographically and by using a surface-tracking resistance probe. The limiting condition at which
the jet breaks through the kerosene or corn oil layer and reaches the water layer was determined experimentally. A phenomenological
model for the prediction of penetration depth is developed for both short and long jet heights for liquid baths with and without
a second liquid layer on top. 相似文献
18.
应用欧拉-欧拉模型建立了钢包内钢液流动及混合过程的数学模型,考察了吹气量对中心底吹及偏心底吹钢包内流场及均混时间的影响。计算结果表明,钢包底部四周为流动缓慢区域;吹气量越大,一方面可以降低均混时间,另一方面会导致钢包自由液面的钢液流速增大,从而容易造成卷渣;从缩短混合时间,提高生产效率考虑,偏心底吹更为有利。 相似文献
19.
Pulsating bottom-blowing was proposed to strengthen the electric arc furnace (EAF) molten bath stirring. The fluid flow characteristics and stirring effects of different pulsating bottom-blowing modes on EAF molten bath were studied through water model experiments and numerical simulations. The mixing time was measured by water model experiments and the flow field characteristics of EAF molten bath were simulated by numerical simulations. Compared with conventional bottom-blowing, pulsating bottom-blowing can accelerate the fluid flow velocity and improve the stirring of molten bath. With pulsating bottom-blowing, the molten bath fluid flow field is more disorder, the fluid flow velocity increases and the dead zone volume decreases. Compared with EAF steelmaking with conventional bottom-blowing conditions, pulsating bottom-blowing technology can improve the metallurgical effects and the molten steel quality in EAF steelmaking with lower FeO content of final slag, lower phosphorus content and carbon-oxygen equilibrium of final molten steel, and lower temperature deviation. 相似文献
20.
The structure of foaming synthetic BOF-converter slags was studied by freezing the foam and using ocular examination. The foams were generated by CO gas formed due to the reaction between FeO in the slag and carbon in the hot metal. The character of the foams varied a lot with slag composition. Slag with lower viscosity resulted in foams with small gas bubbles, while slag having high viscosity resulted in very big bubbles. 相似文献