A numerical investigation of gas and solid flow as well as the liquid accumulation in a scaled Blast Furnace (BF) model was carried out using the discrete element method (DEM) coupled with ...computational fluid dynamics (CFD). This three dimensional simulation considers the interaction of the solid flow of a layered burden column with the counter flowing process gas. The influence of the cohesive zone is modeled by a material dependent permeability, the molten iron and the slag are considered as one additional liquid phase in the hearth. The method used is compared with a two dimensional numerical slot model presented in former publications by Zhou et al. and then applied to a different three dimensional setup. The comparison of the models exhibits considerable differences concerning the general multiphase flow behaviour. Moreover, it is shown that three dimensional models are required to correctly resolve the actual spatial flow structure and its influence on the shape of the coke free region in the hearth. Finally, the three dimensional model is used to show the influence of the liquid discharge on the stress distribution along the walls.
Snapshot of gas and solid flow pattern in a scaled three dimensional Blast Furnace model. Display omitted
•Three dimensional DEM-CFD modeling of a scaled blast furnace model.•Comparison of the model with previous publications.•The impact of different liquid levels on the particle arrangement in the lower part is investigated.•Effect of simplified liquid iron discharge is shown.
•Transient simulation of the blast furnace hearth considering the tapping cycles and the periods in-between.•Novel approach for modelling the inflow of liquid slag and liquid hot metal.•Hot metal ...density described as a function of temperature and carbon content with an additional transport equation and dissolution model for carbon.•Thermal stratification and transient evolution of properties of the tapped liquids obtained.
In the ironmaking blast furnace, layers of coke, ferrous burden (sinter, pellets, lump ore) and additions are heated by an uprising gas flow. While the layers are descending, the iron ore is reduced and begins to melt. The liquid products slag and hot metal trickle downwards into the hearth, where they prevail as two immiscible phases filling the voids within the coke bed and with the slag floating on top of the hot metal. As the hearth is lined with carbon blocks, which are eroded by the passing hot metal flow, this region has a major impact on the campaign length of the blast furnace.
The blast furnace hearth is drained intermittently by opening the taphole and closing it to end the tap. Hence, the fluid phases in the hearth are in a transient state with the liquid levels constantly varying and the flow conditions being determined by the tapping/non-tapping state. In addition, dissolution of carbon into the hot metal and cooling applied to the refractory affect the local hot metal flow.
This work presents a CFD-model, which is capable to calculate the multiphase flow in a 3-dimensional hearth at an industrial scale. The tool allows for modelling of the transient transport processes, including multiple tapping cycles by utilizing new approaches for the transition between tapping/non-tapping and the inflow of liquids into the hearth. Furthermore, the dissolution of carbon, energy transport in the liquids and the locally varying density of hot metal depending on temperature and carbon content are included.
With this approach, thermal stratification and circulation effects induced by buoyancy can be described over a period of nearly 8 h, thus covering 4 tapping cycles. In addition to an analysis of energy, carbon content and velocity fields, the transient evolution of tapped hot metal properties (temperature, carbon) are obtained and compared to available plant data.
•Assessment of a demand charge on electricity consumption in the commercial sector.•A clustering technique is applied to generalized electricity consumption patterns.•Electricity consumption ...decreased after implementation of a demand charge.•Effects of demand charge vary between cluster segments in the commercial sector.
Demand-based charges have been employed as a tool intended to reduce electricity users’ maximum demand but there is a lack of consensus regarding their efficacy. One reason for this may be the diversity in the flexibility potential of different types of users. This study explores the flexibility potential of different types of electricity consumers in the small to medium-sized commercial sector (35-63A) in response to a compulsory demand charge. The objective is to characterize varying levels of flexibility with respect to different types of commercial users with different load patterns. A multivariate clustering technique was used to group commercial users with comparable load patterns based on a year of hourly data before the tariff change was introduced. This method was used to: (1) match users from the intervention area and reference area with similar load patterns, without losing any user data, and (2) compare how users with different load patterns react differently to the tariff change. We found clear distinctions in the types of commercial users in each cluster and their response to the tariff, demonstrating the extent to which demand flexibility may be dependent on the nature of an organization’s activities and its respective load patterns. The highest demand flexibility was found in clusters which had a large share of users in the IT sector, commerce and public administration. The lowest demand flexibility was found in the real estate and education sectors. Future research should further investigate these variations and explore the possibilities of tailoring interventions to the specific types of users.
Brucellosis, caused by the bacteria of the genus Brucella, is one of the most neglected common zoonotic diseases globally with a public health significance and a high economic loss among the ...livestock industry worldwide. Since little is known about the distribution of B. abortus in Egypt, a total of 46 B. abortus isolates recovered between 2012–2020, plus one animal isolate from 2006, were analyzed by examining the whole core genome single nucleotide polymorphism (cgSNP) in comparison to the in silico multilocus variable number of tandem repeat analysis (MLVA). Both cgSNP analysis and MLVA revealed three clusters and one isolate only was distantly related to the others. One cluster identified a rather widely distributed outbreak strain which is repeatedly occurring for at least 16 years with marginal deviations in cgSNP analysis. The other cluster of isolates represents a rather newly introduced outbreak strain. A separate cluster comprised RB51 vaccine related strains, isolated from aborted material. The comparison with MLVA data sets from public databases reveals one near relative from Argentina to the oldest outbreak strain and a related strain from Spain to a newly introduced outbreak strain in Egypt. The distantly related isolate matches with a strain from Portugal in the MLVA profile. Based on cgSNP analysis the oldest outbreak strain clusters with strains from the UK. Compared to the in silico analysis of MLVA, cgSNP analysis using WGS data provides a much higher resolution of genotypes and, when correlated to the associated epidemiological metadata, cgSNP analysis allows the differentiation of outbreaks by defining different outbreak strains. In this respect, MLVA data are error-prone and can lead to incorrect interpretations of outbreak events.
Brucellosis is one of the most common neglected zoonotic diseases globally, with a public health significance and a high economic loss in the livestock industry caused by the bacteria of the genus ...Brucella. In this study, 136 Egyptian Brucella melitensis strains isolated from animals and humans between 2001 and 2020 were analysed by examining the whole‐core‐genome single‐nucleotide polymorphism (cgSNP) in comparison to the in silico multilocus variable number of tandem repeat analysis (MLVA‐16). Almost all Egyptian isolates were belonging to the West Mediterranean clade, except two isolates from buffalo and camel were belonging to the American and East Mediterranean clades, respectively. A significant correlation between the human case of brucellosis and the possible source of infection from animals was found. It seems that several outbreak strains already existing for many years have been spread over long distances and between many governorates. The cgSNP analysis, in combination with epidemiological metadata, allows a better differentiation than the MLVA‐16 genotyping method and, hence, the source definition and tracking of outbreak strains. The MLVA based on the currently used 16 markers is not suitable for this task. Our results revealed 99 different cgSNP genotypes with many different outbreak strains, both older and widely distributed ones and rather newly introduced ones as well. This indicates several different incidents and sources of infections, probably by imported animals from other countries to Egypt. Comparing our panel of isolates to public databases by cgSNP analysis, the results revealed near relatives from Italy. Moreover, near relatives from the United States, France, Austria and India were found by in silico MLVA.
Ultrahigh molecular weight polyethylene (UHMW PE) has high chemical resistance, good flexibility and remarkable strength along with low density, which makes it a good choice for lightweight textile ...reinforced composites. One drawback is the low melting point, limiting the possible applications at high temperatures. However its chemical structure leads to almost no chemical interactions of the interface. One way to enhance these interactions is the application of atmospheric pressure plasma. Polyethylene (PE) as yarn and in woven form was plasma treated in atmospheric air plasma generated by means of dielectric barrier discharge technique and the resulting effects on wettability, chemical composition and surface structure were studied. It was found that oxygen containing functional groups are introduced into the outer layer of the PE, thus increasing wettability and dyeability significantly. It could be shown that the changes last for at least 3 months in air without the necessity of any precautions. A degradation of the textile fibre during air plasma treatment was also observed, leading to a decrease of tensile strength and maximum elongation after more than five minutes of air plasma treatment.
The effects of two dosages (200 mg, 600 mg, placebo) of a cholinergic nootropic (WEB 1881 FU) were investigated in a visual spatial attention task. Event-related brain potentials (ERPs) were used as ...a physiological measure of attention as they have previously been shown to be sensitive to allocation of attention to points in space. The typical enhancement of several peaks of the visual ERP due to attention was found in the present experiment. No systematic effect of the medication was revealed, suggesting that the effects of WEB 1881 FU do not extend to early perceptual processes.
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