210 t顶底复吹转炉溅渣护炉模拟研究

对某厂210 t顶底复吹转炉进行了溅渣护炉水模型实验,测定了炉衬不同部位的溅渣量,考察了操作参数对溅渣效果的影响,得到最佳工艺操作参数为：顶吹流量50000 Nm3/h,枪位3680 mm,氧枪喷头倾角15°,留渣量21 t,底吹元件布置方式A1,底吹流量900 Nm3/h.     

炼镍转炉溅渣护炉过程中溅渣层形成机理

对炼镍转炉溅渣护炉期间镁铬残砖溅渣层的化学成分、熔化温度、粘度、物相结构及形成机理进行了研究. 结果表明,溅渣初始砖衬表面形成了以铁氧化物为主的过渡层;炉渣进一步挂结,形成由铁镁橄榄石和磁铁矿构成的粘渣层,其中MgO含量上升至11.01%,半球点温度达1424℃;溅渣后下一炉冶炼过程中,过渡层中铁氧化物通过扩散与镁铬砖作用形成以高铁尖晶石和镁铁固溶体为主的反应层,其中Fe2O3含量由1.33%增至18.43%,半球点温度升高至1598℃. 砖衬单炉损耗率降低近一半,炉龄大幅提高.     

Experimental Splash Studies of Monodisperse Sprays Impacting Variously Shaped Surfaces

Despite numerous studies of the drop impact phenomena, studies of the fundamental mechanisms of how the splash corona and subsequent necking yield splashed droplets, not to mention characteristics of these splashed droplets, remain a subject of great interest. Here, we consider a simple question: After impact, what are the characteristics of splashed droplets? Spatial variations in the fraction of splashed liquid, Sauter mean diameter, and drop-size distribution for water and diesel impacting onto variously shaped rods are reported. Liquid drops of nearly uniform size are continuously injected onto a 2-mm-diameter aluminum cylindrical rod at velocities of up to 17 m/s. The impact face of the rod is flat with angles from θ = 0 to 60° or it has a concave, convex, or conical shape. The experimental results indicate that diesel breaks up more easily than water due to its low surface tension. However, due to increased energy loss through viscous dissipation during drop collapse and spreading, dispersion of diesel drops upon and after impact is less energetic than that of water since diesel droplets do not travel as fast or as far as water droplets. During corona formation, stretching and necking of diesel drops before their snap-off are particularly evident due to diesel's high viscosity. Size distribution of splashed diesel droplets is more uniform than that of water near the impact region and water is more uniform further away.     

Non-isothermal laminar pipe flow — I. Theoretical

The Graetz-problem — heat transfer to a fluid flowing laminarly in a circular tube with constant temperature — has been extended to the case of a variable viscosity. Calculations are performed on the heat transfer to and the hydrodynamics of non-isothermal, rectilinear, laminar flow of incompressible, power-law fluids in round tubes. The consistency-index is assumed to vary exponentially with temperature.The results are presented as logarithmic mean Nusselt-numbers and dimensionless velocity distributions and pressure drops as a function of the dimensionless axial length in the tube and as function of a quantity Q which measures the deviation of “isoviscous” fluid behaviour. It turns out that the heat transfer rate is a unique function of the velocity gradient at the wall.All results are summarized in a few practical approximations.     

Polyester molding compounds: Partial systems and related particulate composites

Several binary of ternary systems, consisting of an unsaturated polyester resin and one or two additives which are currently considered in formulating polyester molding compounds (such as BMC and SMC) were studied in relation to some of their relevant properties as a function of their composition. The additives were: MgO as a thickening agent; a thermoplastic polymer (PS or PVAc); and a fine CaCO₃ particulate filler. Measured quantities were, depending on the system physical state (fluid or crosslinked): viscosity, linear shrinkage, flexural modulus and strength, and fracture toughness and energy, besides SEM morphological characterization. Quantitative relations could in several instances be expressed; in particular, the relation between strength and filler volume fraction was found to follow the linear equation of the simplest area reduction “random model”.     

On the non‐newtonian viscous behavior of polymer melts in terms of temperature and pressure‐dependent hole fraction

A new theoretical non‐Newtonian viscosity model is developed by taking the fractional series expansion of Eyring's shearing strain rate. A broad range of experimental rheological data of various polymer melts including polyethylenes, polypropylene, polystyrene, poly (methyl methacrylate), and polycarbonate are fitted well using the proposed model. From the model; zero shear, constant shear‐stress and constant shear‐rate viscosities are derived as a linear function of viscosity related quantity, Y_h, called “thermo‐occupancy function” and their coefficients are discussed in detail. The thermo‐occupancy function is expressed in terms of temperature and structural vacancies such as hole fraction computed from the Simha‐Somcynsky Hole Theory (SS). In addition, the derivative of the logarithm of viscosities with respect to the hole fraction, named as viscoholibility, is observed decreases with the increasing hole fraction. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40540.     

Heat transfer to jackets with close clearance impellers in viscous materials

“Viscous mixing” as defined here includes the range of 5000 to 500,000 centipoises at 5 sec-1 fluid shear rate. It was found that heat transfer coefficient with helical impellers were related to the clearance between the impeller and the tank wall and not influenced to any important degree by the speed or the fluid viscosity. The mechanism seems to be conduction through this stagnant film. “Convection-type” correlations are not useful in describing the effect of operating variables.     

What is the role of “pressure” in the use of capillary and slit flows to determine the shear‐rate dependent viscosity of a viscoelastic fluid?

The purpose of this review article is to clear the confusion created by some investigators, who erroneously thought that the pressure transducers mounted on the wall of a capillary or slit die measured a quantity that could meaningfully be called “pressure,” accurately stated “indeterminate isotropic contribution to the total stress,” and then reported on the effect of “pressure” on the shear‐rate dependent viscosity of a viscoelastic fluid. On the other hand, reference to such a quantity is not needed to calculate the wall shear stress and thus shear viscosity in fully developed flow of incompressible, viscoelastic polymer melts in a capillary or slit die; instead only information on the gradient of the total wall normal stress is needed. Further, it is pointed out that much of the literature discussing “pressure shift factor” to describe the effect of “pressure” on the viscosity of polymer melts in flow through a capillary or slit die is based on an erroneous belief that there exists a physically meaningful isotropic “pressure” that can be measured. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.     

From Cross‐linking to Plasticization – Characterization of Glycerin/HTPB Blends

Usually, a plasticizer is a relatively low‐viscosity liquid ingredient that is added to improve the mechanical properties and the processing properties of a propellant, such as a lower viscosity for casting or a longer pot life of the mixed, but uncured propellant. The effects of many plasticizers on the performance of the composite propellant have been studied in detail. Glycerin is a triol, a low viscosity material, and inexpensive. It seems that the processing properties and the mechanical properties of the HTPB binder would be improved by the addition of glycerin. The curing behavior, the mechanical properties, and the thermal decomposition of a glycerin/HTPB blend have been investigated in this study. The viscosity of the glycerin/HTPB blend and the increasing ratio of the viscosity versus the elapsed time are lower than those of only HTPB. The mechanical properties are improved by the addition of glycerin, even for a low quantity of glycerin. The thermal decomposition behavior of the blend occurs at lower temperatures when compared to that of HTPB.     

撞击流反应器内幂律流体流动特性的数值模拟

采用数值模拟方法对撞击流反应器内幂律流体的流动特性进行研究,分析了不同喷嘴间距和入口流速下清水和不同质量分数幂律流体的径向射流扩展率、径向速度衰减率、剪切应力、表观黏度等分布规律,研究表明：幂律流体中径向射流的径向速度分布规律与清水径向射流相似。随喷嘴间距的增大,扩展率增大,径向速度衰减率减小,平均剪切应力呈先增大后减小的变化规律,其中L=3D时平均剪切应力值最大,更利于流体混合。入口流速越大,扩展率越小,径向速度衰减率越大,平均剪切应力也随之增大。幂律流体的平均剪切应力大于清水,且随质量分数的增大,其扩展率增大,为清水扩展率的1.3~3.3倍,而幂律流体的径向速度衰减率从-1.268~-1.125降低到-1.144~-1.082,逐渐小于清水。幂律流体径向射流区域的剪切应力呈“M”形分布,表观黏度则呈“W”形分布,流体的流变性质对撞击流反应器内流体的流动规律影响显著。     

A comparison of torsional and capillary rheometry for polymer melts: The Cox-Merz rule revisited

Rheological properties of high and low density polyethylene melts (HOPE and LDPE) were measured under two different deformation modes: sinusoidal strain (“dynamic”) and constant rate-of-strain (“steady-state”). For the sinusoidal measurements, a torsional geometry was used, whereas the “steady-state” measurements were carried out in both torsional and capillary flow. The complex and “viscous” components of the “dynamic” viscosity were compared with the “steady-state” viscosities, corrected for both non-Newtonian and end effects. For the HDPEs, the Cox-Merz rule was found to be not valid. The corrected viscosity is closer in magnitude to the “viscous” component, and not to the complex viscosity. However, for the LDPEs, the corrected viscosity is equivalent to the complex viscosity. These results are compared to other correlations found by various authors.     

一种新型水基压裂液酸性交联剂的制备

采用无机锆盐为原料,制备了一种酸性压裂液用交联剂。所合成产物具有低伤害、耐温、延缓交联时间等特点。经过实验,得到最佳反应条件为反应介质是异丙醇的水溶液,m(氧氯化锆)∶m(H2O)∶m(异丙醇)=1∶1.25∶2.5,m(葡萄糖酸钠)∶m(氧氯化锆)∶m(丙三醇)=1∶16∶20,反应温度50～55℃,pH=2,反应时间4h。通过实验研究,由所合成交联剂LY-2与羟丙基瓜尔胶交联得到的压裂液具有良好的性质,交联时间120s,冻胶黏度可以达到524mPa.s,耐温温度170℃,加入2%破胶剂(质量分数15%过硫酸铵)1h后,冻胶黏度可降至1.56mPa.s。     

On the rheological behaviour of batch crystallisations

During batch processing the formation of a solid phase is often accompanied by a significant reduction in the mobility of a reaction mass as a “soft” solid is formed. Often the fluid becomes stagnant with a mobile zone or “cavern” around the agitator. This phenomenon was investigated using two in situ probes: (i) a particle size probe which detected the onset of crystallisation and (ii) a viscosity probe which detected the onset and extent of rheological problems. The viscosity probe measurement appears to correlate with the yield-stress of the slurry. A mechanistic analysis of the phenomenon suggests a new dimensionless number: the Nienow number (Ni), the ratio of turbulent stresses to the yield stress of a fluid. Complete mobility is generally achieved for Ni > 30. These systems scale with tip speed if super-saturation is controlled.     

Prediction of melt elasticity from viscosity data

A simple method for predicting the primary normal stress function, θ, from viscosity data is proposed. A relation between θ and the viscosity function, θ, based on the Goddard-Miller rheological equation of state, is given. An easy-to-use generalized chart for estimating θ from θ is presented; in order to use this chart, viscosity data must be available from the zero-shear-rate value of the “power law region.” The method was applied to six polymer melts, three polymer solutions, and an aluminum soap solution for which θ had been measured experimentally. Even though θ varied by a factor of 10³ over the examined range of shear rate, the theory and experiment seldom differed by more than a factor of 2. The generalized chart for θ was combined with Tanner's theory to prepare a graph which may be used to estimate jet swell from viscosity data. Comparison with experimental data of jet swell for 4 polymer melts shows good agreement.     

缩放管内带衰减性自旋流的复合强化传热研究

以水、质量分数50%和85%的甘油为工质,对缩放管内分别插入的10种不同结构形式旋流片的传热性能进行实验研究.结果表明:相同实验流量范围内,以传热强化综合因子η为目标,在水为介质下,η均小于1,不适用.在质量分数50%甘油为工质下,旋流片的扭率为2.52,旋转角为180°,间距为383 mm时,η最大,在1.08-1....     

THE VISCOSITY EFFECT TO THE DYNAMIC CHARACTERISTICS OF A CONTINUOUS-FLOW AGITATED TANK

In this work, the viscosity effect to the dynamic characteristics of a continuous-flow agitated tank cooled by jacket were studied both experimentally and theoretically. The mathematical model of this tank was developed and it was solved with Laplace transformation. Theoretical results were compared with the experimental data

To see the effect of the viscosity change in the feed fluid to the transient behaviour of the tank, step changes were given to the feed and coolant flow rates at different glycerin concentrations. Also, perturbation was given to the input concentration of the glycerin solution, and the results were compared.     

ROLL COATING IN THE PRESENCE OF A FIXED CONSTRAINING BOUNDARY

When a cylindrical roll rotates about its axis while partially submerged in a liquid, as suggested in Figure 1, a layer of the liquid is entrained and withdrawn from the bath. In the absence of a constraining boundary the coating thickness H is found to exhibit a strong dependence on roll speed, as well as on the fluid viscosity and interfacial tension. In a previous publication (Middleman, 1978) from this laboratory we have presented experimental results and a successful data correlation for the case of a roll operating under such conditions that the boundaries of the fluid reservoir exert no influence on the coating dynamics. In this paper the effect of an adjacent constraining boundary is considered, a mathematical model based on lubrication theory is presented, and the data are found to exhibit the general features predicted by the model. Under some conditions it is observed that a uniform coating is not achieved. Instead, a regular set of lines or “ribs” is developed, in the direction of motion. Figure 2 shows this situation. This instability is anticipated and described in the work of others, and a theory of Savage (1977) is evaluated with respect to our own data on critical conditions for onset of “rib” formation. The general features predicted by that theory are consistent with our observations.     

Optimized data collection for determination of the MWD from the viscosity data of polymer melts

Numerical differentiation is one source of loss of resolution in the differential transformation of viscosity to MWD. Resolution can be improved by increasing the amount of viscosity data, keeping in mind that optimizing this process is necessary for practical reasons. This problem was approached by finding the minimum point for practical reasons. This problem was approached by finding the minimum point density and coverage required to resolve bimodality. For given point density and range, the higher the superposition between the viscosity data and the “knee” in the viscosity function produced by each mode, the better the resolution. Testing time can be reduced and resolution can still be preserved by placing more points in the “knee” region in the viscosity function and by skipping the unnecessary points at low shear rates.     

Nonlinear viscoelastic behavior of butadiene–acrylonitrile copolymers filled with carbon black

Various viscoelastic measurements including dynamic mechanical measurements in tension at 110 Hz from ?60° to 160°C, tensile stress relaxation measurements with 100% elongation at 25°, 54°, and 98°C, capillary flow measurements at 70°, 100°, and 125°C, and high-speed tensile stress–strain measurements carried to break at 25°, 56°, and 98°C were performed on four samples of carbon black-filled butadiene–acrylonitrile copolymers. All the data were treated with the same equation for time–temperature conversion. The capillary viscosity–shear rate curves were significantly lower than the complex viscosity–angular frequency curves, indicating “strain softening” with extrusion. The viscosity was estimated from the stress–strain relationship at the yield point. The viscosity as a function of the strain rate is significantly higher than the complex viscosity as a function of angular frequency, indicating “strain hardening” with extension. The strain softening and strain hardening are attributable to the structural changes upon deformation of the carbon black-filled elastomers. With the unfilled elastomers, neither strain softening nor strain hardening were observed in similar measurements.