Comprehensive numerical modeling of raceways in blast furnaces

A numerical investigation of dynamic raceway formation in an industrial-scale blast furnace is performed using Computational Fluid Dynamics (CFD) coupled with a Discrete Element Method (DEM). The industrial-scale simulations are made feasible by incorporating the Flamelet Generated Manifold (FGM) method and a coarse-graining method to reduce the computational cost while ensuring effective modeling of gas phase combustion and a large number of solid particles, respectively. The model considers the interactions between pulverized coal (PC) and coke, as well as their interaction with gas. The simulations reveal a different size and shape of the physical and chemical raceway, indicating that not all crucial reactions occur within the physical raceway. According to the model, the physical raceway formation is primarily determined by the blast air momentum, and the PC combustion has a negligible effect on its dimensions. The chemical raceway formation heavily depends on the oxidation rate of coke. The utilization of PC is quantified in terms of burnout. Smaller PC particles are found to undergo a higher degree of burnout due to faster convective heating and oxidation rates. Modifying the angle of the PC injection lance in current configuration is found to be inconsequential to PC burnout. The presented results highlight the significance of enhancing PC-blast mixing to improve PC utilization and provide new insights into optimizing blast furnace operations.</p

CFD Approach to the Influence of Particle Size on Erosive Wear in Coal Riser Pipes

Pneumatic conveying of finely pulverised coal particles is an important process in the steelmaking industry, used to transport coal to the blast furnace. Erosive wear caused by high velocity particles impacting on the inner wall surfaces of pneumatic conveying riser pipes causes a severe problem in the steel-making industry. Continuous erosion left unmaintained eventually leads to pipe punctures. This paper aims to help minimise the erosive wear in industrial risers by investigating the effects of different particle sizes on the wear rates in industrial coal conveying ducts to control the grind size in industrial gas-solid flow processes and optimise reduced wear. Computational fluid dynamics (CFD) simulations and 4 semi empirical erosion models were used to analyse these effects, with an Eulerian-Lagrangian technique to model the multiphase gas-solid flow in the riser. The continuous phase (air) was modelled by solving Eulerian Reynolds-averaged Navier Stokes equations and the discrete phase (coal) was modelled using the Lagrangian discrete phase model (DPM) approach. The particle sizes investigated ranged from 1 to 1000 µm. The results showed the curves for each erosion model representing the changes in erosive wear with an increase in particle size for each erosion model. Every model showed similar curve shapes but varied in degree of wear rates. The curves of each model showed a steady increase in wear between particle diameters of 1 and 150 µm, followed by a sharp increase in wear at 200 µm, with the maximum erosion rates recorded between 300 and 350 µm. Subsequently, the wear rates began to drop, with a steady decrease in wear with particle diameters between 600 and 1000 µm. The behaviour of the curves was characterised by analysing the Stokes’ number and kinetic energy at each particle size. It was concluded that the sharp increase at 200 µm occurred, due to the number of particles (which possess sufficient kinetic energy) and the number density escaping the continuous phase and impacting the riser walls. Larger particles may have possessed greater individual kinetic energies; however, the fewer particles tend to impact the riser walls at higher particles sizes due to significantly lower number densities, resulting in a decrease in wear rates

The effect of childhood adversity on 4-year outcome in individuals at ultra high risk for psychosis in the Dutch Early Detection Intervention Evaluation (EDIE-NL) Trial

Childhood adversity is associated with a range of mental disorders, functional impairment and higher health care costs in adulthood. In this study we evaluated if childhood adversity was predictive of adverse clinical and functional outcomes and health care costs in a sample of patients at ultra-high risk (UHR) for developing a psychosis. Structural Equation Modeling was used to examine the effect of childhood adversity on depression, anxiety, transition to psychosis and overall functioning at 4-year follow-up. In addition, we evaluated economic costs of childhood adversity in terms of health care use and productivity loss. Data pertain to 105 UHR participants of the Dutch Early Detection and Intervention Evaluation (EDIE-NL). Physical abuse was associated with higher depression rates (b=0.381, p=0.012) and lower social functional outcome (b=-0.219, p=0.017) at 4-year follow-up. In addition, emotional neglect was negatively associated with social functioning (b=-0.313, p=0.018). We did not find evidence that childhood adversity was associated with transition to psychosis, but the experience of childhood adversity was associated with excess health care costs at follow-up. The data indicate long-term negative effects of childhood adversity on depression, social functioning and health care costs at follow-up in a sample of UHR patient

A new syndrome with noncompaction cardiomyopathy, bradycardia, pulmonary stenosis, atrial septal defect and heterotaxy with suggestive linkage to chromosome 6p.

Contains fulltext : 69194.pdf (publisher's version ) (Closed access)We report a three-generation family with nine patients affected by a combination of cardiac abnormalities and left isomerism which, to our knowledge, has not been described before. The cardiac anomalies include non-compaction of the ventricular myocardium, bradycardia, pulmonary valve stenosis, and secundum atrial septal defect. The laterality sequence anomalies include left bronchial isomerism, azygous continuation of the inferior vena cava, polysplenia and intestinal malrotation, all compatible with left isomerism. This new syndrome is inherited in an autosomal dominant pattern. A genome-wide linkage analysis suggested linkage to chromosome 6p24.3-21.2 with a maximum LOD score of 2.7 at marker D6S276. The linkage interval is located between markers D6S470 (telomeric side) and D6S1610 (centromeric side), and overlaps with the linkage interval in another family with heterotaxy reported previously. Taken together, the genomic region could be reduced to 9.4 cM (12 Mb) containing several functional candidate genes for this complex heterotaxy phenotype