X-ray Radioscopic Visualization of Bubbly Flows Injected Through a Top Submerged Lance into a Liquid Metal

Metallurgical and Materials Transactions B - We present an experimental study on the formation and behavior of a liquid metal bubbly flow arising from a downward gas injection through a top...     

Mathematical Modeling of Impinging Gas Jets on Liquid Surfaces

In top-blowing operations, the gas jet is a major source of momentum, so to model the momentum exchange properly with the liquid, the full-stress boundary conditions must be applied. A new mathematical method for better representation of the surface boundary condition was developed by combining the Cartesian cut cell method and volume of fluid method. The computational code was validated with the broken dam problem and reported critical phenomena in wave generation. The model was applied to impinging jets on liquid surfaces in two dimensions. The cavity depth was in good agreement with experimental measurements. The process of ligament and droplet formation was reproduced. The extent of momentum transfer to the liquid was investigated, and the trends with lance height and gas flow rate were similar to experimental evidence. The following important aspects of momentum transfer were identified: surface roughness as well as the development of local pressure gradients around wave crests. Kelvin–Helmholtz instability theory was used to interpret the results with respect to critical velocity for the onset of droplet formation. These principles were extended to conditions relevant to basic oxygen furnace (BOF) steelmaking. The critical velocities for droplets were calculated as functions of the physical properties for the gas–steel, gas–slag, slag–steel interfaces. The implications for BOF steelmaking were discussed. The mathematical model was applied to a simplified configuration of full-scale BOF steelmaking, and the local force balance was well described.     

Using CFD Modeling to Improve the Inlet Hydraulics and Performance of a Storm-Water Clarifier

The feasibility of high-rate treatment of storm water achieving total suspended solids (TSS) removals in the range from 60 to 80% was studied using an available clarifier. The clarifier (3?m long, 1.4?m wide, and 2?m deep) was fitted with a removable lamella pack and had a limited flow capacity (surface load rate of 35?m/h). To achieve the desired removals of TSS, the clarifier required polymer feed (4?mg/L), which caused maintenance problems during intermittent storm-water treatment—laborious and costly cleaning of lamella plates after individual storm events. This problem posed the following challenge: was it feasible to avoid costly maintenance by removing the lamella pack and at the same time to retain the high TSS removals by improving the clarifier hydraulics by internal structural changes? The purpose of the paper is to evaluate such changes by focusing on different inlet configurations designed using computational fluid dynamics (CFD) simulations. This analysis resulted in adopting a U-tube duct inlet (inserted into the outer box of the original clarifier) with two special features: (1) three horizontal slot openings (width = 0.1?m) releasing flow into the clarifier and (2) a narrow slot opening in the bottom U bend allowing removal of grit. The flow release slots in the rising leg of the U tube were fitted, along the upper edge, with horizontal trailing plates protruding 0.15?m into the clarifier and forcing the flow to move horizontally. This clarifier design performed well, but storm-water grit accumulated at the bottom of the U tube, which had to be cleaned out after individual storms to avoid plugging. This issue was resolved by allowing grit to move into the sludge storage compartment of the clarifier through a narrow tilted slot opening in the U-tube bottom. The final clarifier design with polymer feed, without lamellas, produced TSS removals comparable to those in the original lamella clarifier (almost 80%), but at a higher surface loading rate (43?m/h, which was limited by the feed pump capacity). CFD modeling, in comparison to conventional methods of hydraulic design, served as a flexible and powerful tool providing distinct advantages with respect to the speed, efficiency and reduced cost of analysis, and a better understanding of the clarifier operation.     

气相色谱法测定液氧中碳氢化合物的浓度

较为详细地介绍了用氢火焰离子化气相色谱法测定液氧中碳氢化合 及该方法中所涉及的主要操作参数的选择依据和原则。     

Detailed Modeling of Gas Flow in Liquid Steel: Bubble Size Distribution and Voidage Calculation

Although the role of gas purging in liquid steel systems is well recognized, it has yet to be adequately analyzed. One key aspect of this process is the prediction of gas voidage in the bath, which has been studied in great detail beginning with water modeling in the early days and using advanced multiphase models more recently. Still, there are significant unresolved issues with gas purging systems. When gas is introduced through a nozzle at high flow rate, a jet may form which is undesirable. The break‐up of this jet into bubbles is a separate topic of research. The more common practice in the steel industry is to use porous plugs for gas injection. Gas entry through a porous plug can be characterized by the stretched bubble regime, and the laws of coalescence and fragmentation used to analyze bubble column reactors are generally applicable. Calculation of the bubble size distribution is important for two reasons. First, the voidage distribution in the bath is significantly modified by the injection system and flow rates used, primarily due to changes in flow regime and bubble dynamics (collision, break‐up, coalescence). Second, the voidage distribution directly determines the buoyancy, that influences the physical mixing process, and the specific‐area‐density, that influences surface reactions (for example, decarburization, desulfurization and nitrogen pick‐up). In this paper, a numerical study is presented that combines a bubble dynamics model with an Eulerian multiphase model. The results of the simulation are compared with the experimental data from Anagbo and Brimacombe (1990). Relevant discussion and reviews will be presented to distinguish the differences of this detailed bubble dynamics model with the uniform bubble diameter approximations reported in various recent studies.     

复吹转炉射流与钢水熔池相互作用的水模型试验

根据鞍钢180 t复吹转炉的实际生产情况,设计了超音速射流氧枪并进行水模型实验,避免了亚音速射流氧枪所带来的氧枪枪位修正问题.通过10:1水模型.保证最佳的底吹工艺参数不变(4孔对称,底吹流量0.70m3/h),改变顶吹氧枪的气体流量(38-42 m3/h)和吹炼枪位(130-210 mm)进行实验.结果表明:水模型最佳的工艺参数是枪位150 mm,流量39 m3/h.     

Regimes of Micro-bubble Formation Using Gas Injection into Ladle Shroud

Gas injection into a ladle shroud is a practical approach to produce micro-bubbles in tundishes, to promote inclusion removal from liquid steel. A semi-empirical model was established to characterize the bubble formation considering the effect of shearing action combined with the non-fully bubble break-up by turbulence. The model shows a good accuracy in predicting the size of bubbles formed in complex flow within the ladle shroud.     

Simulation and Application of Submerged CO2-O2 Injection in Electric Arc Furnace Steelmaking: Modeling and Arrangement of Submerged nozzles

Metallurgical and Materials Transactions B - The technology of submerged CO2-O2 injection was developed to enhance the circulation in liquid baths and accelerate the smelting reaction rate in...     

p-Wave Reflection Imaging of Submerged Soil Models Using Ultrasound

An ultrasonic p-wave reflection imaging system is used to noninvasively image submerged soil models with embedded anomalies and complex geometric layer contacts. The ultrasonic transducers emit compressive waves into water that subsequently transmit into the underlying soil, and measurements of the reflections are used to construct the images. The properties of the transducers and data acquisition hardware and software are explained. Fast signal stacking is used to improve signal-to-noise ratio and provide clearer images. Transducer directivity is explained as a wave passage effect, and transfer functions are derived for square and circular transducers to quantify directivity. The transfer functions agree reasonably with measured amplitude data. The cause of errors in the imaged position of dipping reflectors is explained, and a Kirchhoff migration algorithm is implemented to correct these errors. A soil model consisting of embedded high- and low-impedance anomalies, dipping soil layer contacts, and an undulating concrete base layer was imaged using 500- and 100-kHz transducers. The geometric features of the model are clearly visible in the images recorded with the 500-kHz transducers and less clear with the 100-kHz transducers. The lateral spatial resolution of the migrated images is shown to be much larger than one wavelength.     

Modeling and Simulation of Spray Forming of Clad Deposits with Graded Interface Using Two Scanning Gas Atomizers

A three-dimensional shape model based on a surface coordinate tracking method has been developed for clad deposits with graded interface which are spray formed using two scanning gas atomizers. The calculation of element distributions in the deposits has been incorporated into the shape model. On this basis, the deposit shape and the element distributions in the deposit have been simulated. It shows that the scanning mode of the atomizers and the degree of overlapping of the two sprays play important roles in the spray forming of clad deposits. A concentration gradient of chemical elements in the deposits can be achieved under proper processing conditions. Finally, the modeling and simulation of the spray forming of clad deposits have been validated by experimental investigations.     

旋冲塔湿法烟气脱硫工艺在烧结球团生产中的应用

着重介绍了旋冲塔湿法烟气脱硫的工艺流程、特点及在兴澄钢铁公司的应用,并与其它几种主流烟气脱硫方式进行了技术特点的比较,开拓了钢铁企业根据实际情况选择脱硫方式的思路。     

Injections into the duodenum and the induction of satiety in the rat.

Examined ways in which the intestine might participate in the induction of satiety, using direct intestinal injections to alter the contents of the duodenum and then observing the effect on subsequent food intake over a 21/2-hr period. Ss were 24 male hooded rats, food-deprived for approximately 17 hr. The injection of either bulk or hypertonic solutions (NaCl or glucose) into the duodenum suppressed food intake. The injection of substantial amounts of food did not have an effect greater than that caused by equivalent amounts of nonnutritive bulk and the injection of acid material did not suppress eating more than basic material. These results suggest that bulk and osmotic pressure in the duodenum may initiate physiological changes which can ultimately participate in the regulation of meal size but that metabolites, duodenal hormones, and specific dynamic action do not. With the gastrointestinal system intact, the flow of material from the stomach to the intestine would be sufficiently slow that neither changes in duodenal bulk nor osmotic pressure would be involved in the regulation of meal size. When the stomach is partially removed or denervated, the rate of passage of food into the duodenum may increase enough so that osmotic and bulk signals originating in the duodenum would help to regulate meal size. (French summary) (33 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CFD Modeling of Solid Separation in Three Combined Sewer Overflow Chambers

The knowledge of solid behavior in combined sewer overflow (CSO) chambers is a great challenge for the protection of receiving watercourses. Moreover, great attention must be given to the occurrence of deposits on the bed of the chamber because they may lead to operation problems. In this paper, we investigate the capability of a particle tracking approach to determine the solid separation in CSO chambers. This is done by comparing simulations and experimental data collected in three small-scale models, as reported by Kehrwiller 1995. The trap, reflect, and bed shear stress (BSS) boundary conditions are compared. We propose to use the Shields relationship for evaluating the critical BSS. Finally, we propose a methodology for predicting the solid separation in CSO chambers using computational fluid dynamics.     

TRT高炉顶压自动控制系统的设计与实现

文章介绍了ABB DCS控制系统在万钢1 #高炉TRT中的应用,并在简单介绍高炉煤气余压回收透平(TRT)工艺及其优点的基础上,重点说明了TRT高炉顶压调节自动控制系统的重要性及实现方法.实际应用表明,该系统能够满足机组安全、高效运行之需求.     

CFD Modeling of Particulate Matter Fate and Pressure Drop in a Storm-Water Radial Filter

This study examined a common form of filtration, a passive radial cartridge filter (RCF) system, to physically separate hetero-disperse particulate matter in rainfall-runoff. The RCF tested utilizes aluminum-oxide coated media with a uniform pumice substrate (d50m = 3.56?mm) gradation. To examine the RCF, this study applied laser diffraction and real-time pressure sensor measurements to validate a computational fluid dynamics (CFD) model to predict particle separation and filter head loss for hetero-disperse particulate matter (PM). Filter hydrodynamics are resolved using a macroscopic approach for the porous media with a k-ε turbulence model coupled with the Ergun equation. PM fate was resolved using a discrete phase model. CFD results closely followed measured data for filtration and head-loss response for all flow rates. With influent PM at 200?mg/L (d50m = 16.3?μm), effluent PM ranged from 32?to?57?mg/L for surface loading rates of 24?to?189?L/m2?min, respectively. There was agreement between measured and modeled data for effluent PM and head loss. CFD postprocessing provided added insight into the mechanistic behavior of the RCF by means of three-dimensional hydraulic profiles, particle trajectories, and pressure distributions, illustrating that a RCF is nonuniformly loaded. As part of design and regulation, such physical testing coupled with modeling is a required precursor to uncontrolled field testing, regular maintenance and certification of a BMP.     

Flowrate Measurement in Turbulent Liquid Metal Channel Flow Using Time-of-Flight Lorentz Force Velocimetry:Experimental Investigations and Numerical Modeling

Lorentz force velocimetry(LFV)is a suitable non-contact technique to measure flow velocity and flowrates in electrically conducting high-temperature melts.LFV is based on the principles of magnetohydrodynamics:when an electrically conducting fluid passes the field lines produced by a magnet system,eddy currents are induced within the fluid.The interactions of the eddy currents with the magnetic field generate Lorentz forces.Using LFV the counterforce acting on the magnet system is measured.Such a flowmeter consists of a permanent magnet system and an attached digital force sensor.The force recorded by the flowmeter is proportional to the flowrate Q and depends on both the electrical conductivityσof the fluid and the spatial distribution of the applied magnet field B.However,in metallurgical applications,σis often unknown or fluctuates in time as it strongly depends on both temperature and composition of the melt.In the present paper we investigate a technique called Time-of-Flight Lorentz force velocimetry ToF LFV.In this technique,the flowrate can be determined by just cross-correlating the two force signals recorded by two flowmeters which are arranged one behind the other separated by a certain distance D.Sensing the passage of the triggered vortices,this ToF LFV measures the transit timeτof these vortices.Then we recalculate the velocity V according to the relation V=D/τ.We experimentally and numerically study turbulent liquid metal flow in the test facility EFCO(electromagnetic flow control channel)using the eutectic alloy GainSn as a test fluid.Our experiments show that this electromagnetic ToF LFV is well suited to determine the flow velocity and flowrate.The experiments are accompanied by numerical simulations using the commercial program package FLUENT.     

Modeling of Liquid Steel/Slag/Argon Gas Multiphase Flow During Tundish Open Eye Formation in a Two-Strand Tundish

Metallurgical and Materials Transactions B - Multiphase flows are frequently encountered in metallurgical operations. One of the most effective ways to understand these processes is by flow...     

高炉无钟炉顶煤气探测器的设计特点与应用

天津铁厂为解决原煤气取样机不能及时准确分析、判断高炉运行状况的问题,采用目前国内较先进的煤气温度探测技术,实现了高炉运行状况的实时监控,降低了劳动强度,提高了生产作业率,为高炉的顺利生产和经济运行起到了很大作用.文章介绍了天津铁厂煤气温度探测器的结构设计特点及使用效果.