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关键词： Dry coal beneficiation   Gas-solid fluidized bed   Spatial characteristics   Separation performance   Regional feeding  

摘要： To study the fluidization characteristics and separation performance of a gas-solid dense-phase fluidized bed, bed space structure and force analyses of particles in the radial and axial zones are explored. The results indicate that the standard deviation and average bed density increases with increases in the static bed height. As the fluidization number is increased, the average bed density decreases and fluctuates drastically. Under the same fluidization number, the density in the upper layer is low with violent fluctuations, and it is relatively lower in middle layer and higher on the side wall. The ratio of the minimum pressure gradients in the axial and radial zones in the fluidized state was 10, which proved that the main movement mode of particles is settlement motion in the axial direction. The probable error values were 0.095 and 0.097 g/cm(3) in optimal test conditions, indicating efficient separation of 13-25 mm coal particles. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Stochastic differential equations   Wong-Zakai approximation   Malliavin calculus  

摘要： We investigate the regularity of the law of Wong-Zakai-type approximations for Ito stochastic differential equations. These approximations solve random differential equations where the diffusion coefficient is Wick-multiplied by the smoothed white noise. Using criteria based on the Malliavin calculus we establish absolute continuity and a Fokker-Planck-type equation solved in the distributional sense by the density. The parabolic smoothing effect typical of the solutions of Ito equations is lacking in this approximated framework;therefore, in order to prove absolute continuity, the initial condition of the random differential equation needs to possess a density itself. (C) 2019 Elsevier Inc. All rights reserved.

关键词： Linear-implicit Crank-Nicolson scheme   Linear-implicit leap-frog scheme   Momentum-preservation   Fourier pseudospectral method  

摘要： We propose two conservative linear-implicit schemes for the space fractional Korteweg- de Vries (fKdV) equation. One is the linear-implicit Crank-Nicolson scheme and the other is the linear-implicit leap-frog scheme. In order to obtain a high order discretization in the space direction, we adopt the Fourier pseudospectral method. The Crank-Nicolson scheme and leap-frog scheme are used for temporal discretization, and those two schemes are efficient in practical computations because of their linear property. Furthermore, we analyse the uniqueness, boundness, convergence of the two schemes. Numerical experiments are presented to validate the theoretical analysis. (C) 2019 Elsevier Inc. All rights reserved.

关键词： Zhundong coal   Oxy-fuel   Ash formation   Sodium and potassium   Density functional theory  

摘要： Zhundong coal is promising to replace inferior coal in fossil-fueled power plants, considering its high abundance, low contents of sulfur and nitrogen. However, the relative high contents of alkalis, especially sodium and potassium, damage the operational economy and safety badly since the release of alkali metals in flue gas can lead to fly ash-related problems such as slagging, ash accumulation and corrosion. Although, oxy-fuel circulating fluidized bed (CFB) combustion is beneficial to reduce the release of sodium and potassium by lowering the operation temperature, the ash formation characteristics of Zhundong coal under the oxy-fuel CFB is still scarce. Our results showed that the residual amounts of sodium and potassium in the ash samples, both tend to decrease with increasing temperature no matter under air combustion or oxy-fuel combustion. However, the sodium content in the cinder obtained under the oxy-fuel combustion atmosphere was higher than that under the air combustion atmosphere, and the insoluble sodium, mainly existed in the form of aluminosilicates, was the main form. In addition, the increase of steam content in both atmospheres reduced the sodium content in the cinder while the residual amount of potassium increased. Density functional theory calculations verified the transformation behavior between sodium and potassium and the inhibiting effect of steam. This study elucidates the release and migration characteristics of sodium and potassium in Zhundong coal both experimentally and theoretically and will benefit the popularity of Zhundong coal.

关键词： 流体包裹体   成矿流体   同位素   矿床成因   塘坝金矿床  

摘要： 塘坝金矿床位于西秦岭金成矿带南部文县—康县金成矿亚带东段,为石英脉型金矿床。野外地质调查发现,矿体主要产于花岗斑岩脉附近的断裂中,在空间上与花岗斑岩脉关系密切,成矿作用可划分为3个阶段。流体包裹体显微测温结果表明:不同阶段成矿流体包裹体类型相近,矿床成矿温度为156.9℃~303.2℃,盐度为1.82%~15.67%,密度为0.76~0.99 g/cm 3,深度为5.18~7.43 km;成矿流体具有中低温度、中低盐度、低密度、中浅成相特征。包裹体激光拉曼光谱分析显示,包裹体气相成分主要为CO 2、H 2O,含少量N 2,液相成分主要为H 2O,属于H 2O-NaCl±CO 2体系。氢-氧-硫同位素分析结果表明,塘坝金矿床δ18 O H 2O为5.98‰~9.87‰,δD V-SMOW为-80.6‰^-74.5‰,δ34 S为-1.9‰~8.0‰;结合矿床野外产出特征,成矿流体主要来源于岩浆热液。综合分析认为,该矿床为与岩浆作用有关的中低温度、中低盐度岩浆期后热液型金矿床。

关键词： 地热流体   水文地球化学特征   水-岩相互作用   共和盆地  

摘要： 地热流体地球化学组成及其运移规律和成因机制研究对地热资源勘查和开发利用具有重要意义。当前,青海省地热资源开发利用程度低,更缺乏针对地热流体地球化学特征进行深入研究的系统性工作。青海共和盆地是青藏高原北缘的一个断陷盆地,盆地内地热资源丰富。本文以共和盆地及周围部分山区的地热系统为研究对象,基于系统地球化学采样和测试开展了地热流体地球化学组成及热储水-岩相互作用过程分析,认为:从共和下更新统热储、新近系热储到鄂拉山构造岩浆带再到瓦里贡山构造岩浆带,地热水中SiO2含量依次升高,反映热储温度依次升高;上述地热地区热储中原生铝硅酸盐矿物的溶解和蚀变矿物的形成是控制地热水中阳离子含量的最重要的水文地球化学过程,而补给水下渗和地热水径流及升流过程中盐类矿物的溶滤则是水中阴离子(特别是SO^(2-)4和Cl^-)的主要来源。

关键词： 激光抛光   连续激光   之型方波路径   表面张力   熔峰填谷  

摘要： 目的解决连续激光高速抛光模具钢的表面质量与效率问题。方法将连续激光高斯光束通过缩束镜和DOE衍射整形器,转变成平顶激光光束。通过激光抛光工艺参数的优化,将光斑直径为470μm的平顶连续激光束,以之型与方波型组合扫描路径和500 mm/s的高速扫描速度,抛光冷作模具钢Cr12MoV,并通过白光干涉仪和SEM电镜检测其表面性能。结果连续激光高速抛光可将表面粗糙度由原始的1.942μm快速降低至0.26μm,抛光效率比传统机械抛光提高了67%,比人工抛光提高了94%,表面显微硬度提高了125%。结论工艺试验表明,连续激光的光斑扫描路径和直径对抛光表面质量产生深远的影响,对冷作模具钢进行高速抛光时,需要对激光功率、光斑直径、扫描速度、扫描路径和扫描间距等激光加工参数进行优化,在达到相同质量效果的前提下,抛光效率是传统机械抛光效率的8倍以上,是熟练技师人工抛光效率的30倍以上。同时,连续激光抛光显著提高了模具钢的表面显微硬度,无任何污染,是一种绿色制造技术。

关键词： 二氧化氯   表面张力   接触角   湿润剂  

摘要： 为有效降低煤矿粉尘浓度,增加湿法除尘的有效性,研究了国际公认的绿色消毒剂二氧化氯作为煤矿除降尘湿润剂的可行性。选用二氧化氯溶液和不同煤阶煤样进行了表面张力、接触角等方面的研究,实验结果表明:浓度为400×10-6时,二氧化氯溶液表面张力为49.63×10-3N/m;二氧化氯作用后千秋矿长焰煤、沙曲矿焦煤和中马矿无烟煤接触角降低幅度分别为33.08%、45.59%和86.14%,表明二氧化氯对煤尘具有较强的湿润性。该研究为二氧化氯在矿井除降尘方面的推广应用提供实验支撑。

关键词： 仪器设计   表面张力系数   吊环  

摘要： 本文设计了一种液体表面张力系数的实验装置,采用电子天平测量液体表面张力大小,以三线调节的方式解决吊环水平问题,并利用制作好的仪器,进行了对比测量,得到准确的实验数据,且实验重复性好.

关键词： 三聚表面活性剂   临界胶束浓度   表面张力   应用性能  

摘要： 以丙三醇,环氧氯丙烷、叔胺为原料通过醚化反应、季铵化反应合成了一种季铵盐型三聚表面活性剂(3C14triQ),应用FTIR和1H NMR对目标产物结构进行了表征。采用表面张力法、电导率法、稳态荧光法对目标产物的表面活性进行了研究,25℃临界胶束浓度分别为0.082(γcmc=30.2 mN/m)、0.087、0.085 mmol/L,与传统表面活性剂和二聚表面活性剂相比具有较好的表面活性;采用分水时间法考察了目标产物的乳化性能,并结合偏光显微镜和激光粒度仪研究了乳液粒径情况,结果表明其乳化性能优于传统表面活性剂,煤油乳液粒径为1481~3574nm,平均粒径为2638 nm。w(3C14triQ)=1%的溶液起泡高度为24.6cm,稳泡性为97.15%。在1mol/L HCl缓蚀介质中,ρ(3C14triQ)=50 mg/L,缓蚀效率可达到95.2%。