Effects of Ultrasonic Waves on Vapor-Liquid Equilibrium of an Azeotropic Mixture

Abstract

Azeotropic and extractive distillation techniques used to separate azeotropic mixtures are among the most challenging separation processes in the chemical industry. In this work, an innovative distillation technique which employed ultrasonic waves was proposed to intensify the conventional multi-column azeotropic distillation method into a single-column alternative. The effects of ultrasonic intensity on the vapor-liquid equilibrium (VLE) of methyl-tert-butyl-ether (MTBE)-methanol was investigated at 50, 100, 200, and 250 W/A·cm² and at a fixed frequency of 40 kHz. Studies were also done to examine the effects of ultrasonic frequency on the VLE data at 25 and 68 kHz frequencies. It was found that ultrasonic waves at 50 W/A·cm² intensity and 25 kHz frequency gave the highest relative volatility (α) at 2.654 and completely eliminated the MTBE-methanol azeotrope, thereby allowing highly pure MTBE to be recovered in just a single distillation column. The results revealed that ultrasonic waves had the potential to favorably manipulate α, and hence, the VLE of an azeotropic mixture.     

包钢炼铁厂降低中速磨废料排出量的措施

包钢炼铁厂喷煤系统中速磨废料排出量大,既浪费资源又影响台时产量,近几年一直在摸索如何降低废料排出量。2001年通过改造中速磨喷嘴环,调整系统参数,废料排出量大幅降低。文中对此次改造的措施及效果进行了分析总结。     

基于C-ALS的空区顶板覆岩冒落分析研究

由于受到探测技术的限制,传统探测方法难以精确地获得复杂空区的实际空间分布形状,这就给技术人员对空区的后续分析和处理带来了很大困扰.为此,文中以龙桥铁矿的0～2线空区作为工程实例,采用三维激光探测系统（C-ALS）对其进行了激光扫描,在获取原始三维点云数据的基础上,借助Surpac软件建立空区三维地质模型,并得到该空区的形状、体积大小、空间位置等信息.在此基础上,对空区顶板覆岩的冒落高度及原因进行了分析,结果表明：空区的实测高度与理论高度值基本接近,该区段空区顶板覆岩基本没有冒落.     

无线局域网在医院中的应用及安全防护

随着无线技术的发展和移动智能终端的普及,医疗行业对无线网络的需求也越来越多,建设医院无线局域网,能提高工作效率和服务质量。文章提出了以无线控制器和AP为架构形式的无线局域网的解决方案,能克服传统无线网络漫游、无法统一管理等的问题,同时给出了安全防护的措施,从而为医院建立一个稳定安全的无线网络环境。     

CHARACTERIZATION OF EFFECTIVE TIRE CONTACT AREA FOR VARIOUS TREAD PATTERNS

The effective tire-pavement contact area affects the relative damage of asphalt pavement and should be incorporated in both mechanistic and empirical response analyses of pavements. A new machine called ROTOCOM Wheel Tracker (RCWT) was designed and fabricated to capture the effective tire contact area apart from slab compacting, and conducting simulative laboratory wheel tracking tests. The main focus of this paper is laboratory measurement of effective tire contact areas for various tread patterns. Seven tire treads were selected for the footprint image analyses at five tire loads and four tire inflation pressures. An image processing MATLAB-based program was coded to calculate the contact areas of the 280 imprints obtained from both sides of the RCWT. Factorial analysis indicated significant effects of tire tread, tire load, and inflation pressure on the resulting contact area. Comparison between effective and traditional contact areas indicated that the current pavement design procedure with traditional circular contact area extremely overestimates the actual tire-pavement contact area up to 92%.     

A new wide area information based power system out-of-step oscillation detecting and oscillation center tracking scheme

A new out-of-step oscillation detecting and oscillation center tracking scheme based on the wide area information obtained from phasor measurement units (PMU) is proposed in this paper. In this scheme, the out-of-step oscillation is detected by the change rate of phase angle difference between bus voltage and system current, and the oscillation center tracking is completed by analyzing the phase angle relation between terminal bus voltages of electrical components and the system current. The scheme is easy to implement, and the tracking result is not affected by the changes of system structure and operation modes. Even in the complicated situations that the impedances of the whole system are nonuniform and the equivalent system potential amplitudes are not equal, it can still work well. The simulation results on PSCAD prove it is efficient. Utilizing the tracking results, a new out-of-step splitting criterion is given with which the splitting section can be determined dynamically according to the real-time operation state of power system.     

Investigation of the effects of recycled engine oil bottoms on asphalt field performance following an oxidation modeling approach

This work investigates the effects of recycled engine oil bottoms (REOBs) on asphalt field performance by comparing asphalts with and without REOBs in terms of the asphalt properties required for pavement oxidation modeling. Specifically, oxidation reaction kinetics parameters, dynamic shear rheometer (DSR) function (DSRFn) hardening susceptibility (HS), and low sheer viscosity (LSV) HS are determined and compared for base binder, 5 wt.% REOBs, and 15 wt.% REOBs blends. At the higher percentage, addition of REOBs appears to increase the initial oxidation rate at field temperatures and significantly increases LSV HS, but does not significantly increase the DSRFn HS. A field modeling example elucidates the effects.     

居住区声环境调研分析--以上海市铁岭路28弄馨怡花园为例

噪声作为一种环境污染，与人们的日常生活质量息息相关。然而越来越多的噪声源，也带来了愈加严重的噪声问题。本文以居住区声音环境为出发点，结合实际调研，剖析出了住区内的噪声问题。并从建筑科学技术的角度，提出了一定的可行措施。     

极不稳定薄煤层采区通风系统之优化

根据天湖山矿区极不稳定煤层的赋存条件，分析历史沿用的开拓开采方式采区通风存在的问题，立足现场实际，提出一些优化方案，并在实践中加以改进。     

Surfactant-assisted synthesis and catalytic activity for SOx abatement of high-surface-area CuMgAlCe mixed oxides

CuMgAlCe mixed oxides were prepared by a modified coprecipitation–calcination method using CTAB as surfactant template. All the precursors showed hydrotalcite-like layered structure and mixed oxides with mainly periclase phase were obtained after calcination. Catalytic activity for SO₂ removal of mixed oxides was examined through adsorption–reduction cycles under the conditions similar to those of FCC units. The results showed that incorporation of both Ce and Cu could improve SO_x oxidative chemisorption. CTAB/metal molar ratio during synthesis had a significant influence on the structural properties of mixed oxides. Sample CuMgAlCe-0.1 prepared by CTAB/metal molar ratio of 0.1 had the highest specific area 142.2 m²/g and also presented the best SO₂ adsorption rate and capacity. This behavior is mainly due to its exposed more adsorption sites provided by high specific surface area, facilitating SO₂ diffusion and contact with active components. It still possessed excellent cyclic stability that is beneficial for industrial application.