Rotational electromagnetic stirring in continuous casting of round strands

A model is presented to compute the three-dimensional flow field in rotational electromagnetic stirring of round strands. The model involves the solution of the Maxwell equations, the Navier-Stokes equations, and the transport equations for the turbulence characteristicsk andε. For the limiting case of one-dimensional stirring, the computations were checked with experiments using mercury as the fluid. Several sets of computations were carried out to determine the influence of stirrer position, stirrer length, and electromagnetic parameters on the flow field in continuous casting of steel strands.     

Precise conversion electron intensities of Eu decay for detector calibration purposes

A double focusing electron spectrometer has been used to determine precise relative intensities of internal conversion electron (ICE) lines following the decay of ¹⁵²Eu in order to produce a suitable standard for solid state electron detectors. Intensities of 21 electron lines are given in the energy range 198 keV to 1.361 MeV with a precision close to 3.5%. For the 0₂⁺−0₁⁺ E0 transition in ¹⁵²Gd, a precise energy of 615.406(11) keV has been established and an X-value of 0.047(5) was derived.     

Microtox Toxicity Test Results for Water Samples from the Detroit River

The toxicities of over 70 water samples from the Detroit River between Lake St. Clair and the western basin of Lake Erie to the bioluminescent Photobacterium phosphoreum were determined with the Microtox toxicity analyzer. The samples were analyzed in the field within a few hours of collection and again several weeks later in the laboratory. After the storage, the samples were fractionated by distillation under vacuum. This process yielded three fractions of each sample of which the first fraction, enriched in some of the volatile contaminants, and the third fraction, containing the non-volatile compounds, were analyzed. High toxicities were found for several of the original samples and also for the first and third fractions of some concentrated samples. Testing of samples with this system provided a general overview of acute toxicity and may be useful for the quick recognition of contamination hotspots.     

Characteristics of eccentric bubble plumes in liquids

The hydrodynamics of air/water plumes in a large scale model of a metallurgical ladle was investigated. The dimensions of the cylindrical vessel were 1600 mm i.d. and 2250 mm total height. The air was injected through an eccentric nozzle positioned halfway between the center and the wall of the vessel. The gas concentration, bubble frequency, and liquid and gas velocities were measured using electrical resistivity probes and a propeller flowmeter. Particular attention was paid to the liquid velocity. Its field is complex and nonstationary. Light scattering experiments on a small scale model were carried out to supplement the velocity data measured in the large vessel. From the analysis of the data, it was found that the maximum values of the gas fraction (time average), the upward liquid velocity, and the gas velocity can be described with the same dimensionless correlations derived previously for the centered plume.     

Application of pure oxygen for the passivation of mild steel in high temperature and pressure Bayer liquor under conditions of disturbed flow

The passivation characteristics of sulfuric acid cleaned mild steel in spent Bayer liquor (pH 14.4 and 160 °C) are examined using a high pressure nickel flow loop. An entrained atmosphere of 99.90% v/v oxygen gas is incorporated as an experimental variable along with Reynolds number (141,700 and 50,950) and intensity of fluid flow disturbance. State of passivation has been defined using criteria derived from transient polarisation resistance measurements and large-scale polarisation, linear sweep voltammetry. In the majority of cases, oxygenation introduces instantaneous passivation of the mild steel on contact with the Bayer liquor. In comparison to de-oxygenated and aerated electrolytes, this rapid rate of passivation can lead to up to an order of magnitude reduction in the quantity of charge associated with metal dissolution over 20 h. Although relative rates of corrosion when passive are low and largely independent of the level of flow disturbance, dissolution rates when passive are somewhat larger at the higher Reynolds number.     

The high temperature reactor - an important tool in meeting the challenge of world energy supply

A growing and, in its majority, poor mankind will need increasing amounts of energy at moderate prices. At the same time, ecological stresses on our environment, on the forests of the Third World (firewood crisis), and on the climate must be limited. The High Temperature Reactor (HTR) is a well-suited answer to all challenges, as it can supply eletricity safely and economically, be built close to process steam and district heat consumers, procure more hydrocarbons from coal relative to a given release of CO₂, and has the potential of splitting water with high efficiency. At times of affluent fossile fuels, however, and not yet apparent need to restrict their use for reasons of climate, individual companies cannot bear the development and introduction of HTRs all by themselves. Therefore governments are called upon for support.