Analysis of the microelement content in coal

Microelements are present in coal in its organic matter, mineral impurities, and biochemical material. The microelement content in these components will be different, on account of the different forms of migration and access to the organic system. Estimation of the microelement content in the basic components of the coal is of interest in terms of assessing the rare-metal content in coal fields and extracting those metals. Statistical analysis of the microelement contents in different components of the coal is proposed.     

煤制烯烃企业全厂能量系统优化策略及应用

为了实现煤制烯烃企业全厂能量系统优化,提出了煤制烯烃企业全厂能量系统基于单元、子系统和全局划分的渐进协同优化策略,包括全厂用能状况分析、工艺装置用能及换热网络优化、低品位热回收和优化利用、全厂蒸汽动力系统优化等步骤。应用上述优化策略,对某60万t/a煤制烯烃企业全厂能量系统优化进行研究,得到全厂各单元能耗分布,提出了甲醇合成和甲醇制烯烃单元换热网络优化、全厂蒸汽动力系统降低蒸汽减温减压量及低品位热合理匹配利用等节能方案,理论上可以提高全厂系统能效3%以上,年节约标煤10万t以上,投资回收期小于1 a。     

Ignition of single coal particles in high-temperature oxidizers with various oxygen concentrations

In this investigation, coal pellets were combusted using a high temperature oxidizer with varying oxygen concentration, using a small scale batch reactor able to preheat the oxidizer to 1273 K. In base of the experimental results, the influence of oxygen concentration on the ignition mechanism, the solid temperature inside the particle at the moment of ignition, the mass lost at the moment of the ignition and ignition time is analyzed and discussed. A theoretical basis for the division of the conditions tested into three ignition regimes is developed and a formula for the prediction of the ignition time directly from the material and oxidizer temperature and oxygen concentration is proposed.     

Profile-Icp法测定精盐水中的微量元素

详细叙述了采用Profile-Icp发射光谱仪测定二次精盐水中Ca、Mg、Sr、Ba、Fe、Ni、Al、Si等元素的方法,讨论了分析时应选择的工作条件和参数,并在所选的工作条件下测试,验证了该方法的准确率、精密度符合痕量分析的要求。     

Lipophilic contributions to the solvatochromism of analogous betaines

A pair of solvatochromic phenolate betaines that differed only in their lipophilicity was synthesized. Their solvatochromic responses in pure solvents, in a DMSO–MeOH solvent mixture as well as in micellar solutions were different, an observation which confirmed the fact that sensor lipophilicity contributes to the interpretation of solvatochromism. Quantum mechanical calculations reproduced the observed spectral differences. Molecular dynamics simulations shed light on the solute–solvent interactions responsible for their differences in solvent mixtures.     

影响对作物供应中微肥的因素及中微肥在农业生产中的应用实例

开发与应用中微肥和硅肥是推广科学用肥,建设现代化农业的重要内容之一.阐述影响土壤对作物供应中微量元素的因素;国内中微肥的使用概况及其在农业中的应用实例.中微肥将在我国肥料产业结构调整中占有重要位置,有广阔的市场开发空间.     

Pyrolysis of subbituminous coal in relation to in-situ coal gasification

Pyrolysis of Roland Seam (Wyodak) subbituminous coal has been investigated from 383 to 1273 K in an inert gas at 0.1 MPa (1 bar). The gas, liquid (condensibles at 0 °C) and solid products were analysed and characterized. Evolution of the major noncondensible gas products was measured quantitatively. By measuring the rate of gas evolution under linear heating conditions the effective activation energy and kinetic frequency factor for release of each gas were determined. These activation energies range from about 80 to 150 kJ/mol. Most of the liquid product was released between 570 and 770 K and was approximately 75% water and 25% organic tar phase. The composition of the organic tar phase was characterized by its elemental composition, boiling-point range, and chromatographic ‘finger-print’. The effect of temperature on the structure of char was determined by analysing changes in elemental composition, surface area, and electrical conductivity.     

ICP-AES同时测定二次盐水中微量元素

介绍了以ICP-AES采用标准加入法测定二次盐水中Ca、Mg、Fe等8种微量元素的方法,优化了工作参数,利用国家标准物质验证了方法的准确度,其相对标准偏差均小于2.00%,标准回收率为94.1%~108.6%。     

Mass spectrometric contributions to problems related to the chemistry of atmospheres

Recent mass spectrometric studies of species and processes relevant to the chemistry of atmospheres are reported. New species have been detected, including HO(3); a stratospheric reservoir of OH radicals; the [H(2)O(+)O(2)(-)] charge transfer complex, central to the atmospheric photonucleation theory; and the OSOSO oxide and its cation, likely present in the Io's atmosphere. As to ionic processes, a new route to tropospheric N(2)O in air ionized by lightning and coronas is reported, as well as the complex chemistry promoted by ionization of ozone/freon and ozone/carbonyl sulfide mixtures and the formation of O(5)(+), relevant to the problem of (18)O excess in stratospheric ozone.     

Maximum solid concentrations of coal water slurries predicted by neural network models

The nonlinear back-propagation (BP) neural network models were developed to predict the maximum solid concentration of coal water slurry (CWS) which is a substitute for oil fuel, based on physicochemical properties of 37 typical Chinese coals. The Levenberg-Marquardt algorithm was used to train five BP neural network models with different input factors. The data pretreatment method, learning rate and hidden neuron number were optimized by training models. It is found that the Hardgrove grindability index (HGI), moisture and coalification degree of parent coal are 3 indispensable factors for the prediction of CWS maximum solid concentration. Each BP neural network model gives a more accurate prediction result than the traditional polynomial regression equation. The BP neural network model with 3 input factors of HGI, moisture and oxygen/carbon ratio gives the smallest mean absolute error of 0.40%, which is much lower than that of 1.15% given by the traditional polynomial regression equation.     

Effect of coal particle size on the coal hydrogenation reaction — In relation to the plasticity of coal

The effect of coal particle size on the catalytic hydrogenation of dry coal was investigated for three Hokkaido coals (Japan) of different ranks. It was found that the effect of coal particle size on conversion is dependent on coal rank. A greater difference in conversion with respect to coal particle size is noticed for coals of lower carbon content. The physical appearance of the products in the autoclave after the reaction suggests that the effect of particle size on conversion is dependent on the plastic properties of the heated coal sample. When the reaction proceeds with coal in the plastic state, the effect of particle size is small. As indicated by the product distribution, the plastic properties of a coal sample are related to the yield of asphaltene (hexane insoluble/benzene solubles) and/or the structural parts of original coal which yield asphaltene.     

Pseudocapacitive contributions to electrochemical kinetics in NiOx electrochromic anodes

Because of its ability to change optical absorption dynamically by applied electric field, nickel oxide (NiO) is a promising anodic material in smart windows, which can improve energy conversion efficiency in construction buildings. Although many works have achieved high electrochromic performance with different method. The underlying mechanism is still not fully investigated. In this article, we prepared the NiO films with large specific surface area and high stability by electron beam evaporation. X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to figure out the surface morphology and composition of as-deposited films. Afterwards, the electrochemical properties and optical performance of the prepared NiO films were investigated. On this basis, the origin of surface charge was fully analyzed by cyclic voltammetry and diffusion coefficient test. These experimental and theoretical results firmly confirm that both the surface reaction and capacitive effect bring about the excellent EC performance in NiO films. These results not only provide clear evidence about electrochemical kinetics in NiO films, but also offer some useful guidelines for the design of EC materials with higher performance and longer stability.     

Precursors to aromatic units in coal

Previous oxidation experiments with bituminous coal have produced fluorenone, benzophenone and anthraquinone carboxylic acids. Precursors to these acids were speculated to be fluorene, diphenylmethane, anthracene and 9,10-dihydroanthracene derivatives. Oxidation experiments suggested that polymethylene bridges between aromatic units may also act as precursors to these acids.     

Main recent contributions to SHS from France

Both in situ TRXRD and IR thermography, on the one hand, and different levels of modeling, on the other, have generated a strong progress in the knowledge and control of numerous SHS reactions. The SHS of simple binary materials, such as intermetallics (FeAl, MoSi₂, NbAl₃, etc.), oxides (e.g. ZrO₂), carbides (e.g. SiC) or nitrides, more complex materials, such as mullite, SiAlONs, MAX phases, composites (SiO₂-Al₂O₃, NiAl-ZrO₂), powders in their more complicated states, such as well controlled microstructures, fully densified intermetallics, smart composites, and hard coatings carried out by GFA researchers greatly contributed to the worldwide competition to harness the potential of SHS. On the occasion of the 40th anniversary of SHS, this paper is giving an overview of the main results obtained by GFA over the last ten years. Dominique Vrel (LIMHP UPR 1311 CNRS-Paris XIII, Villetaneuse)     

神东各选煤厂块煤系统处理能力提升的措施

以提升块煤系统处理能力为目标,对比神东煤炭集团洗选中心各选煤厂块煤系统生产能力,查找制约块煤系统入洗率的主要因素;结合洗选中心管理实际,提出提高原煤筛分效率、拓宽块煤入洗粒级、采取防破碎措施、优化设备工艺性能等改进方案;并针对主要措施进行了经济效益分析,为企业提升块煤系统处理能力提供可行方案和决策依据。     

Somein situ STM contributions to the characterization of electrochemical systems

We present a critical review on the use of STM as anin situ technique to characterize electrochemical systems based on the work performed in our laboratory. Contributions ofin situ STM studies include: (i) atomic resolution of electrodeposited lead on graphite; (ii) imaging of modifications on metallic electrode surfaces induced by electrochemical oxidation-reduction processes; (iii) imaging of corrosion process on aluminium and Al-Ta alloy electrodes in NaCl solution; (iv) characterization of semiconductor-solution interfaces. These studies allowed: (a) establishment of STM as a technique which, for some systems, yields atomic resolution of metallic surfaces in air and in solution; (b) establishment of a mechanism for the electrochemical growth of oxide films on metal electrodes; (c) establishment of a corresponding mechanism for the reduction of those electrochemically grown oxide films; (d) direct monitoring of corrosion processes on a scale of nm to m; and (e) determination of the presence of surface states and their energy position at the semiconductor-solution interfaces.This paper is dedicated to Professor Brian E. Conway on the occasion of his 65th birthday and in recognition of his outstanding contribution to electrochemistry.     

Organic emissions in coal combustion in relation to coal structure and combustion temperature

The pulsed combustion of coal has been studied in a small fluidized-bed reactor. The effect of combustion temperature and coal rank on the organic composition of the off-gas was investigated. Results are presented for the combustion of an anthracite, a medium-volatile bituminous coal and a high-volatile bituminous coal at 700, 800 and 900°C. The analytical techniques used include on-line FT-i.r., O₂ monitoring, FID and off-line g.c.-m.s. using Tenax as adsorbent. About 120 hydrocarbons were found, of which over 80% have been identified. Overall combustion characteristics such as oxygen consumption, total amount of unburned hydrocarbons and swelling properties of the coal have been related to the composition of the organic substances in the off-gas. The distribution of the polycyclic aromatics, from benzene to chrysene, and of alkylated derivatives is discussed in detail. Oxygen-containing compounds have also been analysed, although detailed discussion would be premature.     

FTIR analaysis of coal. 1. techniques and determination of hydroxyl concentrations

The preparation of coal samples for the determination of hydroxyl content by FTIR is described. It is concluded that the FTIR method provides good quality infrared spectra on opaque materials such as coal and char. If sample preparation procedures are followed carefully, quantitative spectra of coals can be reproduced within ±5%. Beer's law is followed in the range 0.3–1.3 mg of coal/cm². The broad absorbance in the range 2000–3600 cm^?1 appears when using several different preparation techniques and is caused by hydrogen-bonded OH. The use of quantitative FTIR specta offers a simple method of estimating the hydroxyl content of a coal. Reasonable results have been obtained despite the problem of interference by water. The KBr pellets were dried for 48 h at 105 °C and the absorbance was reduced at 3200 cm^?1 and the problem of scattering was minimized by using a rectilinear baseline. With these procedures the hydroxyl oxygen concentrations in the coal were determined to an accuracy of ±10%.