Intelligent sensor for coal powder rate injection in a slag cleaning furnace

An intelligent sensor for estimating the coal powder rate injected into a slag-cleaning furnace (SCF) was developed at Caletones Smelter, Chile. At present the estimation algorithms are only based on discharged cycle average information, leading to large prediction errors. In this paper an improved estimation of the current coal rate is presented, based on the instant tank weights, the tank pressure and the position of the control valves, among other variables. Better control of coal addition into the batch process increases copper recovery from slags and reduces the particulate material pollution. An hybrid expert and fuzzy supervisory control is proposed.     

Computational investigation of non-premixed hydrogen-air laminar flames

Laminar diffusion hydrogen/air flames are numerically investigated. Detailed and global mechanisms are compared. NO formation is modelled by full nitrogen chemistry and the extended Zeldovich mechanism. A satisfactory agreement between the present predictions and the experiments of other authors is observed. Significance of different ingredients of mathematical modelling is analyzed. Minor roles of thermal diffusion and radiation, but a significant role of buoyancy is observed. It is observed that the full and quasi multi-component diffusion deliver the same results, whereas assuming Le = 1 to a remarkable difference. NO emissions logarithmically increase with increasing residence time. NO is the dominating nitrogen oxide. Its share increases with residence time, whereby NO₂ and N₂O show a reverse trend. It is observed that the NNH route plays a remarkable role in NO formation, where the share of the Zeldovich mechanism increases with residence time from about 20% to 85%, within the considered range.     

Analysis of hydrogen storage mechanism in bilayer double-vacancy defective graphene modified using transition metals: Insights from Ti-BDVG(Ti)-Ti

In this study, using the first principles calculation and analysis, we found that the B-doping in double-vacancy defective graphene could effectively increase the binding energy of Ti atoms in each adsorption site, especially in the H2 adsorption site with a maximum binding energy of 8.3 eV. However, N-doped bilayer graphene (N-BLG) reduced the binding energy of Ti atoms by 88% of the adsorption sites. Given these two findings, a B- and N-doped bilayer double-vacancy-defective graphene (Ti-BDVG(Ti)-Ti) was constructed. Our findings also showed that the Ti-BDVG(Ti)-Ti outer surface and inner surface could adsorb 32 and 12H₂ molecules, respectively, of which 22, 20 and 2H₂ molecules are adsorbed by Kubas, electrostatic interactions and chemisorption, respectively. The hydrogen storage mechanism of Ti-BDVG(Ti)-Ti involves multiple adsorption modes, and this hydrogen storage mechanism provides a theoretical basis for the rational design of hydrogen storage materials with maximum effective hydrogen storage capacity.     

Increasing electron transfer and light absorption in graphited nanocarbon-conjugated g-C3N4 nanosheet heterostructure for photocatalytic hydrogen evolution

Accelerating the charge separation and transfer as well as increasing the visible light absorption is of great importance for photocatalysts to realize efficient photocatalytic hydrogen evolution via water splitting. Herein, for the first time, we fabricated in-plane graphited nanocarbon-conjugated polymeric carbon nitride (GNC-C₃N₄) nanosheet heterostructure photocatalyst from melamine and hexaketocyclohexane octahydrate mixture via an amino-carbonyl reaction. The incorporation of GNC into conjugate network of C₃N₄ can not only dramatically enhance the light harvesting but also significantly promote the charge separation and transfer by the built-in electric field and intimate interface in the coplanar GNC-C₃N₄ heterostructure. Accordingly, the optimal GNC-C₃N₄ photocatalyst demonstrates a more than 15-fold enhancement for photocatalytic hydrogen evolution from water under visible light irradiation, compared to C₃N₄.     

基于灰色关联度的埋地管道检测数据分析

目的通过对胜利油田技术检测中心2014和2015年检测的管道数据进行调研、分析,找出影响管道防腐层质量的主要因素。方法利用灰色关联度分析方法,以差劣等级防腐层长度占管道长度的比例为参考序列,分析了运行年限、运行温度、操作压力、土壤埋深以及土壤电阻率等因素对其影响程度。结果通过对数据的分析,发现运行温度和运行年限与防腐层质量的关联度较大,并分别分析了这两个因素对防腐层质量的影响规律。结论油田防腐层质量的关联度排序是:工作温度运行年限埋深土壤电阻率运行压力。通过分析得出,在工作温度为50~70℃的管道中,防腐层的差劣等级所占的比例较大,在管道检测时应重点检测该温度范围内的管道防腐层。运行年限超过20年的管道,差劣等级的防腐层所占比例直线上升,管道防腐层老化严重,检测管道时应该缩短检测周期,及时对防腐层破损处进行合理维修。     

Numerical simulation of convective heat transfer between air flow and ceramic foams to optimise volumetric solar air receiver performances

Porous ceramic foams are used to achieve high performance in solar heat recovery systems. Understanding the convective heat transfer between the air flow and the ceramic foam is of great importance when optimising the volumetric air receiver. In this work, the convective heat transfer was numerically studied. The present approach was designed to compute the local convective heat transfer coefficient between the air flow and a porous ceramic foam. For that purpose, the energy balance and the flow inside the porous ceramic foam were solved. In addition, a detailed geometry of the porous ceramic foam was considered. The ceramic foams were represented by idealised packed tetrakaidecahedron structures. The numerical simulations were based on the three dimensional Reynolds-averaged Navier–Stokes (RANS) equations. A sensitivity study on the heat transfer coefficient was conducted with the porosity, velocity and mean cell size as parameters. Based on the numerical simulation results, a correlation for the volumetric local convective heat transfer coefficient between air and ceramic foams was developed. The resulting correlation covers a wide range of porosities, velocities, cell sizes and temperatures. The correlation results were compared with experimental data from the literature, and the comparison shows good agreement. The correlation is intended to be used in the design of volumetric solar air receivers.     

Materials in RE: Key to renewables exploitation

Those who see renewable energies as naturalistic and representing a return to ‘earth values’ might be surprised at the nature of some of the materials that are key to achieving sustainable energy usage on a commercial scale. Some, indeed, are exotic: products of science and technology at the highest levels. George Marsh reports.