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Abstract. Cooling strategies in continuous casting of steel can vary from rapid cooling to slow cooling, mainly controlled by adjusting the amount of water sprayed onto the surface of the product. Inadequate adjustment however can lead to local surface undercooling or reheating, leading to surface and inner defects. This paper focuses on cooling efficiency of Air-Mist nozzles on casted steel and the experimental and numerical prediction of surface temperature distributions over the product width. The first part explains the determination of heat transfer coefficients (HTC) on laboratory scale, using a so called nozzle measuring stand (NMS). Based on measured water distributions and determined HTC's for air-mist nozzles using the NMS, surface temperatures are calculated by a transient 2D-model on a simple steel plate, explained in the second part of this paper. Simulations are carried out varying water impact density and spray water distribution, consequently influencing the local HTC distribution over the plate width. Furthermore, these results will be interpreted with regard to their consequence for surface and internal quality of the cast product. The results reveal the difficulty of correct adjustment of the amount of sprayed water, concurrent influencing water distribution and thus changing HTC distribution and surface temperature.

During accidental releases of toxic gases emergency responders use different measures to eliminate the threat of a toxic gas cloud. Case studies from incidents in Vienna or in Trieben in Austria showed the need for studies on the effectiveness of such measures. An Trieben in 2009 IBC tank with 1,000 l of nitric acid (53%) was flipped over by a forklift and cracked open in the top area. The content was fully released and lead to serious corrosion effects on storage racks combined with the production of critical amounts of nitrous fumes. A storage and chemical handling area of several hundred square meters was filled by nitrous fumes with concentrations of up to 100 ppm. Emergency responders used an improvised gas absorption system to clear the area of toxic fumes. Outside the sealed area concentrations of nitrous fumes well below the AEGL‐2 (4h) value for nitrous dioxide where measured. In the course of the analyses of the response, the effectiveness of improvised gas absorption techniques was investigated. For the investigations, chlorine and ammonia in combination with a mobile exhauster, (10,000 m3/h) commonly used by emergency responders in Austria were used. Different methods of gas absorption were investigated and tested on their practical relevance. © 2014 American Institute of Chemical Engineers Process Saf Prog 34: 154–156, 2015

Continuous casting has become a highly developed technology for producing steel grades with the highest surface and internal quality. Adequate numerical simulation tools have accompanied this enormous progress in process development with practical relevance for continuous casting. Computation modeling so far addresses a wide variety of the phenomena involved such as heat transfer, fluid flow, thermomechanics, phase transformations, and all aspects of product quality, as recently reviewed by Thomas. [1] For process control, standard solidification models solve the heat-transfer equation in 2D or 3D under stationary or transient boundary conditions and provide information about shell growth and temperature distribution. [2] For online process models, the quality of the thermal boundary conditions and the thermophysical properties of the cast steel grade is decisive for the accuracy of the calculation results.The working group M 2 CC at Montanuniversitaet Leoben has been working on the experimental and numerical simulation of quality-relevant aspects of casting for decades. Meanwhile, the characterization of phase transformations in steels [3][4][5] and the assessment of thermodynamic databases [6] have become a further research focus. The numerical models, databases, measurement techniques, and laboratory experiments developed are linked in the noncommercial offline "casting development platform" m 2 CAST, schematically illustrated in Figure 1. [7] The main emphasis behind the solidification model m 2 CAST is the transfer of process information to lab experiments and vice versa. The general concept and individual steps can be summarized as follows:Thermodynamic data in the material module m 2 MAT is based on extensive internal differential scanning calorimetry (DSC) measurements and thermodynamic calculations, for example, by FactSage 8.0 software and its databases. [8] The calculated thermophysical properties of the steel grade of interest, for example, phase fractions, heat capacity, thermal conductivity, and density, are required to solve the heat conduction equation.In the caster configurator, the slab dimensions and geometry, that is, thickness, width, and casting gap, must be defined along with the mesh size.