Numerical and Experimental Investigation on Heat Propagation Through Composite Sinter Bed With Non-Uniform Voidage. Part I Mathematical Model and Its Experimental Verification

The mechanisms of heat transfer through the sinter beds of the MEBIOS process are discussed and their comprehensive mathematical model is proposed. The MEBIOS process, the concept of which has been proposed earlier by the authors, allows using both coarse and fine particles of iron ores in the same sinter bed. The study includes two parts. The first part describes the model content and the results of its experimental verification. The model accounts for coal combustion, limestone decomposition, moisture evaporation/condensation, and melting/solidifying of solid phases. The model predictions are in good agreement with the experimental data. Typical numerical results of the sintering process and the key parameters influencing the process efficiency are discussed in the second part of the study.     

Numerical and Experimental Investigation on Heat PropagationThrough Composite Sinter Bed With Non-Uniform Voidage:Part Ⅱ Prediction of Process Efficiency

This paper introduces the results of numerical simulation of the MEBIOS sintering process according to the model presented in the first part of the study. The main objective of the second part is the elucidation of key factors influencing the process efficiency, particularly the sintering completeness, velocity of the heat wave propagation and maximum temperature achievable in the pellet during the wave propagation. Numerical results reveal that the mass fraction of coal, diameter of coal particles and air inlet velocity are of prime importance in determining efficiency of the MEBIOS sintering process.     

Numerical and Experimental Investigation on Heat Propagation Through Composite Sinter Bed With Non-Uniform Voidage:Part Ⅰ Mathematical Model and Its Experimental Verification

The mechanisms of heat transfer through the sinter beds of the MEBIOS process are discussed and their comprehensive mathematical model is proposed.The MEBIOS process,the concept of which has been proposed earlier by the authors,allows using both coarse and fine particles of iron ores in the same sinter bed.The study includes two parts.The first part describes the model content and the results of its experimental verification.The model accounts for coal combustion,limestone decomposition,moisture evaporation...     

全氢罩式退火炉退火热过程的研究(Ⅰ)——数学模型及其实测验证

分析了全氢罩式退火炉退火工艺过程的传热特点,建立了以板卷温度计算为核心的退火热过程数学模型,通过模拟计算得到了钢卷退火曲线,并与实测值进行了对比验证.结果表明,该数学模型合理、可靠.     

Pore Blockage Effects on Atrazine Adsorption in a Powdered Activated Carbon/Membrane System. II: Model Verification and Application

The bisolute model developed in Part I of this study to describe the effect of pore blockage on trace organic compound adsorption was verified and then used to study the roles of various design and operating variables on process performance efficiency. Continuous flow experiments were conducted with atrazine and a pore-blocking macroelectrolyte, poly(styrene sulfonate) (PSS-1.8k) using two powdered activated carbons (PACs) in a bench-scale PAC/microfiltration (MF) system. The model was calibrated with one set of experimental data, and verified with additional data obtained at different operating conditions for both PACs. PAC B, which has a large mesopore surface area and volume, was found to be less affected by pore blockage at a given PSS-1.8k surface loading compared to PAC A, which has relatively small mesopore surface area and volume. However, it was also shown that when PAC B was fully loaded with PSS-1.8k, the pore blockage effect on the rate of atrazine diffusion was even greater than that for PAC A due to the higher PSS-1.8k adsorption capacity of PAC B. Model simulations were conducted to investigate the effects of reactor hydraulic retention time, membrane cleaning interval, influent PSS-1.8k concentration, PAC dosage, PAC dosing scenario, and the quality of membrane cleaning water on system performance. Optimal PAC/MF system operating conditions were also determined based on model simulations. The study results showed the effects that different concentrations and adsorbent loadings with pore blocking compounds, such as the pore blocking fractions of natural organic matter, can have, and the importance of mesopores in mitigating the detrimental effect of pore blockage.     

Mathematical Modelling of Molten Steel Flow Process in a Whole RH Degasser during the Vacuum Circulation Refining Process: Application of the Model and Results

A three‐dimensional mathematical model for the molten steel flow during the RH refining process has been applied to the circulatory flow processes in both a practical RH degasser and its water model unit. The model was presented earlier [1] and one of its characteristics is that ladle, snorkels and vacuum vessel are regarded as a whole. Using this model, the fluid flow field and the gas holdups of liquid phases and others have been computed respectively for a 90 t RH degasser and its water model unit with a 1/5 linear scale. The results show that the mathematical model can properly describe the flow pattern of molten steel during the refining process in an RH degasser. Except in the area close to the liquid's free surface and in the zone between the two snorkels in the ladle, a strong mixing of the molten steel occurs, especially in the vacuum vessel. However, there is a boundary layer between the descending liquid stream from the down‐snorkel and its surrounding liquid, which is a typical liquid‐liquid two‐phase flow, and the molten steel in the ladle is not in a perfect mixing state. The lifting gas blown is ascending mostly near the up‐snorkel wall, which is more obvious under the conditions of a practical RH degasser, and the flow pattern of the bubbles and molten steel in the up‐snorkel is closer to an annular flow. The calculated circulation rates for the water model unit at different lifting gas rates are in good agreement with experimentally determined values.