Making blast-furnace smelting more efficient through the injection of heated natural gas

Subjecting natural gas to multi-stage heating by passing it through the cooled cavities of certain tuyere elements instead of coolant water is technically simple to accomplish and makes it possible to heat the gas to 300°C or more, the exact temperature depending on the amount of gas used. The cost of instituting this technology is an order of magnitude lower than the savings realized by injecting heated natural gas into blast furnaces. The injection of heated natural gas into a blast furnace introduces additional heat into the furnace and makes it possible to use more natural gas in the smelting process without reducing the theoretical combustion temperature. It also increases the value of the coefficient that characterizes the replacement of coke by natural gas, since the gas undergoes more complete combustion in this case. Finally, the injection of heated natural gas results in a more uniform distribution of hydrogen across the furnace and allows fuller use of this element in the smelting operation.     

Effect of the dispersity of slip on the main properties of refractory parts used for roasting fine ceramics

Results of a study of the effect of the dispersity of casting slip with scrap of silicon carbide plates on the main rheological and physicomechanical properties of refractories used for roasting fine ceramics are presented. The optimum fineness of milled slip that provides the best physicomechanical properties in the refractories is determined. The effect of the additive of a coarse-grain scrap fraction up to 1 mm in size on the properties of the refractories is considered. The optimum amount of this fraction does not exceed 30%. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 3, pp. 42–46, March, 2000.     

Large Eddy Simulation of Turbulent Reacting Mixing of Liquids in a Coaxial Jet Mixer

Large eddy simulation is used to investigate passive and reactive scalar mixing at high Reynolds Re and Schmidt Sc numbers in order to prove capability of the LES‐SGS micromixing approaches based on the eddy dissipation and DQMOM‐IEM models properly simulating liquid reacting flows. Simulations were performed for a fast neutralization reaction in a confined jet reactor. The mean profiles for passive scalar agree well with measurements. It was shown that the most contribution to the scalar variance is made by large scale motions whereas the contribution of fine scales smaller than typical inertial range scales is negligible. Thus, the existing LES models are capable of predicting the scalar variance at large Sc numbers. The results obtained for reactive transport revealed discrepancies in the determination of micromixing rate and product concentration. A special study was performed to investigate the dynamics of fine structures using locally refined box embedded into global grid. Typical statistical properties of fine structures were reproduced numerically.     

Decomposition of lead azide,pentaerythrite tetranitrate,and a laminate system composed of these substances under vibrational loading

Decomposition of lead azide (LA), pentaerythrite tetranitrate (PETN), and a laminate system composed of these substances under vibrational loading is considered. Sensitivity of these substances to impact and vibrations is determined. Sensitivity of the LA + PETN laminate system to vibrational loading, which is characterized by the degree of decomposition, is substantially higher than that of PETN, but lower than that of LA. Specific features of the mechanism of decomposition of these substances at moderate values of vibration parameters and temperatures of specimen heating are discussed. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 1, pp. 73–79, January–February, 2009.     

Field evaporation of cerium hexaboride

The field evaporation of CeB⁶ single crystal was studied by the atom probe method. The field-evaporated ion flow contains Ce⁺⁴ ions and polymeric clusters of the (CeB_{n k} ⁺ type (n=1–6; k=2, 3). This pattern is significantly different from that observed for a typical field evaporation spectrum of LaB₆, a compound analogous to CeB₆. The difference is explained by the higher strength of the crystal lattice of CeB₆ and by the tetravalent character of cerium.