A New Method for Measurement of Local Solid Flux in Gas-Solid Two-phase Flow

Previous works have shown that the suction probe cannot be used to accurately measure the upward and downward particle fluxes independently. A new method using a single optical probe to measure the local solid flux is presented. The measurement of upward, downward and net solid fluxes was carried out in a cold model circulating fluidized bed (CFB) unit. The result shows that the profile of the net solid flux is in good agreement with the previous experimental data measured with a suction probe. The comparison between the average solid flux determined with the optical measuring system and the external solid flux was made, and the maximum deviationturned out to be 22%, with the average error being about 6.9%. These confirm that the optical fiber system can be successfully used to measure the upward, downward and net solid fluxes simultaneously by correctly processing the sampling signals obtained from the optical measuring system.

Influence of the pressure drop and the air lock on the solid flux in a cross-flow moving bed

The gas-solid flow pattern in a rectangular cross-flow moving bed is simulated by the multiphase particle-in-cell(MP-PIC)model with the Barracuda software.The computed results are verified by the experimental data.In the bed,the actual solid flux generally equals the solid flow rates in the solid feed and discharge tubes.However,these two flow rates are greatly influenced by the air lock and the pressure drop in the solid feed and discharge tubes,namely,the negative and positive pressure gradients,respectively,rather than the traditional opinion that they are merely controlled by the valve openings.The pressure drops in these tubes are calculated by the proposed“common pressure pool with multiple outlets”(CPPMO)and the“common pressure pool”(CPP)methods.It is found that the local gas resistance dominates the pressure drop in the solid discharge tubes,while the gas frictional resistance determines the pressure drop in the solid feed tube.In addition,when the solid flow rate nearly tends to zero in the solid feed tube,the air lock forms.A solid flux equation is then given by considering both the air lock and the pressure drop factors in the cross-flow moving bed.

Minimizing N2O fluxes from full-scale municipal solid waste landfill with properly selected cover soil

Municipal solid waste landfills emit nitrous oxide （N2O） gas. Assuming that the soil cover is the primary N2O source from landfills, this study tested, during a four-year project, the hypothesis that the proper use of chosen soils with fine texture minimizes N2O emissions. A full-scale sanitary landfill, a full-scale bioreactor landfill and a cell planted with Nerium indicum or Festuca arundinacea Schreb, at the Hangzhou Tianziling landfill in Hangzhou City were the test sites. The N2O emission rates from all test sites were considerably lower than those reported in the published reports. Specifically, the N2O emission rate was dependent on soil water content and nitrate concentrations in the cover soil. The effects of leachate recirculation and irrigation were minimal. Properly chosen cover soils applied to the landfills reduced N2O flux.

Mapping Correlation Dimension along the Wall Region of a High-Flux Gas-Solid Riser Using Embedded Solid Concentration Time Series

Analysis of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using embedded solid concentration time series collected from a 76 mm internal diameter and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s air velocity and 50 to 550 kg/m2s solids flux of spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3. Data were analyzed using prepared FORTRAN 2008 code to get correlation integral followed by determination of correlation dimensions with respect to the hyperspherical radius and their profiles, plots of which were studied. It was found that correlation dimension profiles at the centre have single peak with higher values than the wall region profiles. Towards the wall, these profiles have double or multiple peaks showing bifractal or multifractal flow behaviors. As the velocity increases the wall region profiles become random and irregular. Further it was found that, as the height increases the correlation dimension profiles shift towards higher hyperspherical radius at the centre and towards lower hyperspherical radius in the wall region at r/R = 0.81. The established method of mapping correlation dimension profiles in this study forms a suitable tool for analysis of high-flux riser dynamics compared to other analyses approaches. However, further analysis is recommended to other gas-solid CFB riser of different dimensions operated at high-flux conditions using the established method.

Flux vector splitting solutions for coupling hydraulic transient of gas-liquid-solid three-phase flow in pipelines

The gas-liquid-solid three-phase mixed flow is the most general in multiphase mixed transportation. It is significant to exactly solve the coupling hydraulic transient problems of this type of multiphase mixed flow in pipelines. Presently, the method of characteristics is widely used to solve classical hydraulic transient problems. However, when it is used to solve coupling hydraulic transient problems, excessive interpolation errors may be introduced into the results due to unavoidable multiwave interpolated calculations. To deal with the problem, a finite difference scheme based on the Steger- Warming flux vector splitting is proposed. A flux vector splitting scheme is established for the coupling hydraulic transient model of gas-liquid-solid three-phase mixed flow in the pipelines. The flux subvectors are then discretized by the Lax-Wendroff central difference scheme and the Warming-Beam upwind difference scheme with second-order precision in both time and space. Under the Rankine-Hugoniot conditions and the corresponding boundary conditions, an effective solution to those points located at the boundaries is developed, which can avoid the problem beyond the calculation region directly induced by the second-order discrete technique. Numerical and experimental verifications indicate that the proposed scheme has several desirable advantages including high calculation precision, excellent shock wave capture capability without false numerical oscillation, low sensitivity to the Courant number, and good stability.

矿井水直接超滤试验研究

为了解决矿井水处理现有工艺流程长、出水水质不稳定等问题,优化矿井水处理工艺,以河北某矿井水为研究对象,采用直接超滤短流程工艺进行试验研究,探究反洗时长、反洗周期、工作压力等工艺参数对超滤的影响,并筛选膜污染清洗药剂。结果表明:最佳工艺参数为反洗时长120 s,反洗周期60 min,跨膜压差0.25 MPa,在此条件下经过300 min试验测试,膜通量为136 L/(m^(2)·h),维持在初始膜通量的91%,出水浊度稳定在0.05 NTU以下;膜污染最佳清洗药剂为0.2%HCl,对污染前后及酸洗碱洗后的膜片进行SEM和EDS测试分析,结果表明造成酸洗碱洗效果差异的主要因素为矿井水中的硬度离子和铝离子。

盘式实心磁力耦合器气隙磁场分布及转矩分析

针对一台9对极盘式实心磁力耦合器,为研究其气隙磁场分布及转矩,引入层理论模型,将磁力耦合器划分为非导电区域和导电区域两部分,推导二维标量磁位法,求解非导电区域的标量磁位和导电区域的磁场强度,同时引入卡特系数进行校正,推导出盘式实心磁力耦合器的气隙磁密和输出转矩公式;然后,通过有限元软件模拟得到磁力耦合器的三维气隙磁场分布、涡流分布和输出转矩,并分析了不同工作参数对输出转矩的影响;最后,搭建三维气隙磁场测量试验平台和传动试验平台进行三维气隙磁场和转矩的试验,所得试验结果与理论计算结果、仿真结果基本吻合。结果表明,推导的气隙磁密和输出转矩公式具有较高的准确性,为进一步研究盘式实心磁力耦合器的传动特性提供参考。

基于智能试验装置的磷尾砂絮凝沉降特性试验

为提高絮凝沉降试验的智能化水平和分析精准度,采用自主研发的尾砂智能浓密试验装置,进行了磷尾砂絮凝沉降特性试验。研究结果表明:尾砂浆进料浓度与固体通量之间呈倒对勾状的函数关系,在进料浓度10%~18%时对应的固体通量维持在高位;随着尾砂浆进料浓度增大,底流浓度和溢流水浊度均升高,最佳的尾砂浆进料浓度为15%,底流浓度超过72.7%;该尾砂智能浓密试验装置自动化操作和智能化分析提高了试验结果的精准度,可为矿山选择适当的絮凝沉降参数提供参考。

复杂固-液介质的速度应力方程三角形单元间断伽辽金地震波模拟算法

间断伽辽金法可用于存在复杂边界条件的模型,同时具有高阶精度和易于并行计算的优点,因此近年来在地震波传播模拟研究中得到了快速发展.数值通量是间断伽辽金法的关键组成部分之一.相比于其他通量,基于Rankine-Hugoniot跳跃条件的通量(RH-condition通量)在固体和液体介质边界具有更宽的稳定性,可以使用更大的时间步长,尤其是液体和固体之间的波阻抗差异较大时.它已被用于基于四边形网格和速度-应变方程的间断伽辽金地震波固液介质模拟.本文为了模拟陆地自然水体等存在复杂固-液界面形状的地震波传播,并在未来与其他数值方法耦合,发展了基于三角形网格的RH-condition通量间断伽辽金方法,使用一阶速度-压力声波和一阶速度-应力弹性波方程模拟复杂固-液介质中地震波的传播.通过水平层状和sin型起伏固-液模型,验证了该方法模拟结果的准确性.通过数值模拟展示了所提出的间断伽辽金法在不同网格大小和阶数下的准确性和效率.最后通过一个复杂模型的例子表明存在复杂固-液界面时该方法可以准确施加固-液边界条件.

轴向磁通永磁电机混合冷却结构设计与分析

针对轴向磁通永磁电机损耗大和散热困难的问题,提出了风冷结构和混合冷却结构,其中混合冷却结构由端盖风冷结构和定子水冷结构组成。建立了电机的三维模型,采用流固耦合法对电机进行仿真分析,通过对比两种冷却结构的冷却效果,选择了混合冷却结构作为电机的冷却系统。通过仿真分析了流速对电机温升的影响,并根据仿真结果确定了混合冷却结构最佳的入口风速以及水速,证明了混合冷却结构的有效性,为轴向磁通永磁电机的冷却系统设计提供了一定的参考。

两种类型焊丝在桥梁角焊缝中的应用试验及工效分析

桥梁制造大量采用实芯焊丝焊接,与船厂习惯采用药芯焊丝不同,针对公司承接的桥梁单元制作工程,本文使用CO_(2)角焊小车,采用相同直径的实芯焊丝和药芯焊丝在不同的焊接参数、不同的焊接工件角度、不同的焊接工件坡口的工况下进行应用对比试验。通过焊接试验两种焊材的适用焊接参数、焊缝成型、焊接效率等数据,对比分析两种焊材焊接的应用差异和工效差异,并将结论应用于产品建造。

CFD model simulation of bubble surface area flux in flotation column reactor in presence of minerals

Bubble surface area flux(S_b) is one of the main design parameter in flotation column that typically employed to describe the gas dispersion properties, and it has a strong correlation with the flotation rate constant. There is a limited information available in the literature regarding the effect of particle type,density, wettability and concentration on Sb. In this paper, computational fluid dynamics(CFD) simulations are performed to study the gas–liquid–solid three-phase flow dynamics in flotation column by employing the Eulerian–Eulerian formulation with k-e turbulence model. The model is developed by writing Fortran subroutine and incorporating then into the commercial CFD code AVL FIRE, v.2014.This paper studies the effects of superficial gas velocities and particle type, density, wettability and concentration on Sband bubble concentration in the flotation column. The model has been validated against published experimental data. It was found that the CFD model was able to predict, where the response variable as indicated by R-Square value of 0.98. These results suggest that the developed CFD model is reasonable to describe the flotation column reactor. From the CFD results, it is also found that Sb decreased with increasing solid concentration and hydrophobicity, but increased with increasing superficial gas velocity. For example, approximately 28% reduction in the surface area flux is observed when coal concentration is increased from 0 to 10%, by volume. While for the same solid concentration and gas flow rate, the bubble surface area flux is approximately increased by 7% in the presences of sphalerite.A possible explanation for this might be that increasing solid concentration and hydrophobicity promotes the bubble coalescence rate leading to the increase in bubble size. Also, it was found that the bubble concentration would decrease with addition of hydrophobic particle(i.e., coal). For instance, under the same operating conditions, approximately 23% reduction in the bubble concentration is predicted when the system was working with hydrophobic particles. The results presented are useful for understanding flow dynamics of three-phase system and provide a basis for further development of CFD model for flotation column.

Luminescence enhancement of BaMgSiO_4:Eu^(2+) by adding borate as flux

The luminescence of EU^2＋ in BaMgSiO4 with BaB2O4 as flux was studied. The emission spectrum of the phosphor consisted of two bands, peaking at about 398 nm and 515 nm, which were attributed to the emissions from different Eu^2＋ sites in the lattice. When the BaB2O4 flux was applied, the intensity of the 398 nm emission was not clearly affected, but the intensity of the 515 nm emission was enhanced by about ten times. Gaussian fitting showed that the emission band at around 515 nm could actually be resolved into two bands with peak wavelengths of 499 nm and 521 nm, respectively. The assignments of the emission bands to the cation sites were carried out according to the values of bond valence. The overlapping of the 398 nm emission band on the excitation band of 515 nm emission implied that energy transfer could occur from the luminescent center related to the 398 nm emission to the center related to the 515 nm emission, and the energy transfer process remarkably enhanced the intensity of the 515 nm emission band. The phosphor had strong excitation at around 350-400 nm and emitted a bright green luminescence. Thus it could have applications as a green component in solid-state lighting devices assembled by near-UV Light Emitting Diodes （LED） combined with tricolor phosphors.

A Numerical Sirnulation of Gas-Particle Two-Phase Flow in a Suspension Bed Using DifFusion Flux Model

A mathematical model of two-dimensional turbulent gas-particle two-phase flow based on the modified diffusion flux model (DFM) and a numerical simulation method to analyze the gas-particle flow structures are developed. The modified diffusion flux model, in which the acceleration due to various forces is taken into account for the calculation of the diffusion velocity of particles, is applicable to the analysis of multi-dimensional gas-particle two-phase turbulent flow. In order to verify its accuracy and efficiency, the numerical simulation by DFM is compared with experimental studies and the prediction by κ-ε-κp two-fluid model, which shows a reasonable agreement. It is confirmed that the modified diffusion flux model is suitable for simulating the multi-dimensional gas-particle two-phase flow.

Topics on Solid Angles

The purpose of the present work is to derive some solutions for several solid angle cases via a fundamental formula which gives the solid angle for an isosceles triangle. From this formula the solid angle of pyramids is derived but, unlike other presentations, it is shown in a format similar to that of the well-known cone case. Besides the regular polygon cases (straight pyramids), solid angles of some other plane closed curves are calculated. The fundamental formula also leads to some interesting properties showing the not simple behavior of solid angles with the observer point on the curve itself, as it depends on how the observer arrived there. The question of the equi-Ω surfaces is also discussed and calculated in simple cases.

Immersing Treatment of Steel Plate Surface in Steel-Aluminum Solid to Liquid Bonding

The interfacial status of the steel-aluminum solid to liquid bonding plates (their steel plate surfaces were or were not immersed in flux aqueous solution) were measured by using SEM (Scanning Electron Microscope) and X-ray diffraction . The results showed that the layer of flux (the minimum thickness was 15 μm on the steel plate surface) could protect the steel plate surface from oxidizing effectively at high temperature in solid to liquid bonding. The melt temperatUre of the flux should be lower than 580 ℃ so that it could be melted and removed completely. No. 1 flux (patent product made by the author) made up of halogeindes could also force liquid aluminum to infiltrate into steel plate surface and thus the interfacial shear strength of the bonding plate was rather large.

生活垃圾填埋场黄土覆盖层的甲烷氧化能力现场测试和评估

采用静态箱和激光甲烷检测仪等设备开展了50组地表甲烷通量测试,分析了不同龄期垃圾堆体上部土质覆盖层的甲烷氧化能力,并修正了评估现场土质覆盖层甲烷氧化速率和甲烷氧化率的计算方法.结果表明:80%测试点的地表甲烷通量低于澳大利亚CFI(澳洲碳农业倡议)规定限值60g/(m^(2)·d),导气竖井附近20m范围内存在甲烷通量超过CFI规定的排放热点.填埋龄期3~7a堆体的地表甲烷通量从1.13g/(m^(2)·d)下降到0.53g/(m^(2)·d),7~10a的地表甲烷通量基本保持稳定.甲烷氧化速率和覆盖层底部甲烷通量具有正相关性,现场测得的土质覆盖层最高甲烷氧化速率为63.30g/(m^(2)·d),对应的底部甲烷通量为75.95g/(m^(2)·d).每一龄期堆体上部黄土覆盖层的平均甲烷氧化率均超过90%.

助熔成分对工程渣土烧制轻质陶粒性能的影响

目前,利用固体废弃物烧制轻质陶粒的配料设计仍主要依赖于Riley三角形,但由于固体废弃物组成复杂,根据Riley三角形进行陶粒配料设计偶尔会表现出不适用性,而这种不适用性与Riley三角形对原料中复杂的助熔组分不加以区分有关,因此研究不同助熔成分对陶粒烧成过程与性能的影响有重要的意义。本工作设计原料组成在Riley三角形相似的位置,研究了四种常见助熔成分掺量对陶粒烧胀行为、物理性能及晶相组成的影响,并建立三者之间的联系。结果表明,不同助熔成分对陶粒烧胀性能、物理性能及晶相组成有着不同的影响。MgO、CaO及Na_(2)CO_(3)均可明显改善陶粒的烧胀效果,但最佳的掺量及改善效果存在差异:MgO、CaO、Na_(2)CO_(3)掺量(质量分数)分别为1%、1.5%、2%时,分别可制备表观密度为1.38 g/cm^(3)、1.06 g/cm^(3)、0.96 g/cm^(3),单颗粒强度为9.8 MPa、3.9 MPa、4.9 MPa的陶粒。进一步研究表明,这种差异来源于不同助熔成分对晶相组成和液相性质的影响。本工作可为当前工业固废烧制陶粒的配料设计提供一定的参考。

金矿全尾砂浆动静态絮凝沉降规律研究

为获得山东某金矿全尾砂浆静态浓密沉降特性规律,首先采用室内试验对该矿全尾砂进行物理化学特性分析,在此基础上,以控制变量法开展絮凝剂选型试验,然后,以全尾砂浆质量浓度和絮凝剂单耗作为输入因子,固体通量值为响应,采用响应面中心复合设计法(RSMCCD),针对该矿全尾砂浆进行9组全尾砂浆静态浓密试验,根据试验结果建立响应曲面,对响应曲面参数进行可靠性分析。在静态浓密沉降试验基础上,对全尾砂浆进行浓密机动态絮凝沉降模拟试验。结果表明:以固体通量作为评价指标,全尾砂浆絮凝沉降过程,全尾砂浆质量浓度与絮凝剂单耗之间基本不存在交互作用,全尾砂浆质量浓度对固体通量值影响显著性水平高于絮凝剂单耗;当全尾砂浆质量浓度为14.7%和絮凝剂单耗为10.8 g/t时,响应曲面预测固体通量达到最大值为4.18(t/(h·m^(2))),与试验所测实际值误差小于3.5%;浓密机给料速度与底流浓度和屈服应力成负相关关系,与溢流水含固量成正相关关系。试验结果及动态沉降机理分析可为同类型矿山全尾砂浓密系统设计提供试验依据及理论指导。