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关键词： Liquid mixing   dispersion coefficient   solid-liquid fluidized bed   solid-liquid circulating fluidized bed   axial dispersion model  

摘要： Liquid phase axial mixing studies have been carried out in the novel solid-liquid circulating fluidized bed (SLCFB). The SLCFB primarily consists of a single multistage column (having an inner diameter of 100 mm i.d. and length of 1.40 m) which is divided into two sections wherein both the steps of utilization, namely loading (e.g., adsorption and catalytic reaction) and regeneration of solid phase, can be carried out simultaneously in continuous mode. Weak base anion exchange resin was used as the solid phase, whereas water as the fluidizing medium. The effects of physical properties of solid phase, superficial liquid velocity, and solid circulation rate on liquid phase axial dispersion coefficient were investigated. The dispersion coefficient increases monotonically with an increase in the size of solid particle, superficial liquid velocity, and solid circulation rate. The axial dispersion model (ADM) was used to model experimental residence time distribution (RTD) data. A good agreement was found between ADM predictions and the experimental measurements. A unified correlation has also been proposed to determine dispersion coefficient as a function of physical properties of solid and liquid phases, superficial liquid velocity, and solid circulation rate based on all previous and present experimental data on multistage SLCFB.

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： 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： 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： 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： 泛克里金   残差分析   奇异点  

摘要： 由于地质参数空间分布特征存在自相关和互相关的特性,未知点属性值可通过特定方法内插得到。泛克里金插值方法正是结合数据的相关特性,计算未知点属性值的算法。泛克里金方法使用前提是样品点满足正态分布,但正态分布不能代表样品点的地质属性在研究区内具有一定的变化规律,即不能保证趋势函数的有效性。因此,在样品点满足正态分布的前提下,对趋势函数的精度进行研究是必要的。论文提出,在插值过程中,应用多元线性回归拟合样品点在研究区域内的变化趋势,对趋势函数应用残差分析方法,剔除奇异点,可以达到对趋势函数的优化。在实例应用中,运用论文方法对孔隙度数据进行插值,结果与未使用残差分析的泛克里金插值结果相比较,论文方法插值效果更好。

关键词： 流体包裹体   成藏期次   成藏过程   均一温度   石盒子组   苏里格气田西区   激光拉曼光谱分析  

摘要： 通过单偏光显微镜观察、激光拉曼光谱分析及显微测温,对苏里格气田西区16口井50块盒8段储层流体包裹体样品进行了综合测试分析,总结了流体包裹体的岩相学特征,并依据流体成分将包裹体细分为6种类型。分别测试了不同层位、不同产状内与烃类包裹体伴生的盐水包裹体的均一温度、盐度。结果显示:盒8段储层伴生盐水包裹体的均一温度分布在90~180℃,温度主频段分布在120~170℃;石英次生加大边中的伴生盐水包裹体主峰温度比愈合裂隙及微裂隙中的略低,且不存在明显界限。在包裹体均一温度、盐度分析的基础上,结合研究区埋藏史-热史-生烃史,认为苏里格气田西区盒8段天然气为一期成藏,成藏期可依据伴生盐水包裹体均一温度分布特征划分为初始充注期和主充注期2个阶段。初始充注期伴生盐水包裹体均一温度区间为90~120℃,对应于220~160 Ma的中三叠世末—中侏罗世末,主充注期伴生盐水包裹体均一温度区间为120~170℃,对应于160~100 Ma的晚侏罗世—早白垩世末。

关键词： 海水制浆   黑液   防尘涂料   表面张力  

摘要： 为了解决造纸行业水资源短缺、原料短缺以及秸秆制浆黑液难以回收利用等问题,以海水秸秆制浆黑液为介质,以微晶纤维素为填料制备了液体防尘涂料,应用于码头、港口的防尘处理。研究了涂料的组分对涂料粘度、抗水性以及表面张力的影响。结果表明:以海水制浆黑液制备的液体防尘涂料的粒径为461.7nm;添加了2%的瓜尔胶增稠后,粘度达到6107mPa*s;当AKD乳液用量为40%,制浆黑液用量为35%,纤维用量为1%,PAE用量为5%时,制备的液体防尘涂料的表面张力可达30.5mN/m,涂料具有较佳的稳定性以及成膜性。

关键词： 洪泽湖大堤   渗流观测   测压管   资料分析  

摘要： 2000年洪泽湖大堤52K+080堤后发现冒水险情,先后采取堤前防渗板墙截渗、贴坡防渗等方式进行防渗处理,并设置测压管及渗流量等观测设施,以监测堤身渗流稳定情况。通过整理分析2010-2018年洪泽湖大堤52K+080断面渗流观测资料,分析渗流异常原因,找出渗流量及测压管水位变化规律及趋势,复核计算渗流稳定情况,得出洪泽湖大堤52K+080断面渗流稳定和历史险情得到有效控制的结论。

关键词： V-port ball valve   V-angle   experiments and simulations   flow coefficient   pressure fluctuation   energy loss  

摘要： Process valves are responsible for regulating and controlling the rate and direction of flow in pipeline systems. The V-port ball valve is one kind of process valve with a regulating performance influenced by V-angle. In this article, a DN50 V-port ball valve is taken as the research object. This work therefore aims to investigate the effect of and relationship between the V-angle on valve performance and internal flow properties via experiments and numerical simulations. Results indicate that an increase in either V-angle or valve opening causes a large-pressure fluctuation near the valve outlet, thus leading to a long pressure-stable distance. Meanwhile, the flow coefficient increases exponentially with valve opening, and the value of the exponent remains at 2.5 for different V-angles. Furthermore, the stable position of internal energy loss along the downstream pipe is well-matched with the stable position of external pressure fluctuation. This inspires a new method for controlling the pressure stability downstream from the valve. These results may facilitate improvements in the design and optimization of the process valve, thus benefiting the development of fluid transport techniques in energy industries.