旋转流强化管式微滤膜的分离研究

利用无机盐SiO2在旋转流场中进行的分离实验研究,对进料方式、悬浮液浓度及压力影响渗透通量的规律进行了探索,结果表明旋转流场的过滤效果比普通十字流的过滤效果显著,而且是一种非常有效的强化过滤方法。     

A new approach to the mechanism of chlorine evolution: Separate examination of the kinetic steps using ac impedance on a rotating thin ring electrode

In the absence of a bulk diffusion effect, it is shown for the first time that the impedance spectra for the chlorine evolution reaction on a rotating thin ring electrode comprise three consecutive semicircles in the capacitive half of the complex plane. The first (highest frequency) semicircle is due to the charge-transfer resistance for chloride discharge and the simultaneous chlorine adsorption coupled to the double-layer capacitance. The second semicircle (around 5 Hz) is due to the adsorption and desorption of a chlorine intermediate. The third (lowest frequency, around 0.5 Hz) semicircle is due to the relaxation of surface oxygen species. The impedance data allow the steps of the overall reaction to be examined individually. On a Pt surface the rate of chloride discharge and simultaneous chlorine adsorption (the admittance of the first semicircle) is first order with respect to chloride concentration and has a potential-dependence close to 58 mV/decade. The rate of the adsorption and desorption process (the admittance of the second semicircle) is second order with respect to chloride concentration, and has a potential dependence close to 30 mV/decade. The time constant for the adsorption/desorption processes is ca 20 ms, independent of electrode potential in the range studied. These features are consistent with a mechanism in which a faster discharge reaction (Cl⁻ Cl_ad + e) is followed by a slower surface combination reaction (2Cl_ad → Cl₂), but inconsistent with mechanisms in which ion + atom desorption is predominant, the initial chloride discharge is slow, or a unipositively charged chlorine species is involved.     

经孔板形成旋转流的管壳式换热器壳程传热及流阻的研究

对螺旋折流孔板管壳式换热器壳程的传热与流体阻力做了研究 ,给出换热器壳程传热与流阻的计算关联式 ,并采用实验模型对换热器壳程流体旋转流的阻力系数与传热管的局部传热系数做了测试 ,且对光滑和菱形翅片两种管型作了对比     

Bubble Formation at a Rotating Cylindrical Surface in Cross‐Flowing Liquid

A novel method of gas sparging from a rotating cylinder is proposed, which prevents against formation of large attached gas cavities in cross‐flowing liquids including those flowing downwards. Experimental and theoretical results regarding critical rotation speed necessary to remove the attached cavity, bubble formation process and size distribution of the produced bubbles in a low viscosity system (air‐water) are presented in this study.     

Flow influenced electrochemical corrosion of nickel aluminium bronze – Part I. Cathodic polarisation

The cathodic polarisation behaviour of CA 104 nickel aluminium bronze (NAB) has been examined in fully characterised seawaters (filtered and artificial) using the rotating disc electrode (RDE) and the rotating cylinder electrode (RCE). Linear sweep voltammetry and a potential step, current transient technique were used to examine the charge transfer and mass transfer controlled cathodic response as a function of both laminar and turbulent fluid flow. For freshly polished surfaces, the rate of irreversible charge transfer controlled oxygen reduction is controlled by the exchange of a single electron and hydrogen evolution is only significant at potentials more negative than approximately –1.0 V vs. the saturated calomel electrode (SCE).     

Electrochemical removal of cadmium using a batch undivided reactor with a rotating cylinder electrode

The performance of an undivided electrochemical batch reactor with a rotating cylinder electrode under potentiostatic control is examined for the removal of cadmium from a sodium sulfate solution containing 500 ppm Cd(II) at pH ? 7. The effect of hydrogen evolution as a side cathodic reaction on the figures of merit of the reactor is analysed. The best results were obtained for a cathode potential of ?0.9 V against the saturated calomel electrode. With an angular velocity of 1500 rpm the space time yield and the normalized space velocity were 0.66 mol m^?3 s^?1 and 3.9 h^?1 respectively, while the fractional conversion was 67.3% with a current efficiency of 66.7%. The surface morphology of the deposits as a function of the applied potential is also reported. © 2001 Society of Chemical Industry     

Power characteristics of unsteadily forward–reverse rotating impellers in an unbaffled aerated agitated vessel

Power characteristics of an unbaffled aerated agitated vessel with unsteadily forward‐reverse rotating impellers, ie a new type of gas–liquid agitator named ‘AJITER’, treating viscous Newtonian liquids were studied experimentally. Measurements were first made on the agitation torque, ie the torque on the drive shaft on which forward–reverse rotating impellers with four delta‐type blades were attached, and the data obtained were analyzed by fitting them to an equation consisting of two terms with respect to the resistance of the fluid, one due to viscous drag and the other due to added moment of inertia. The effects of operating conditions and physical properties of liquids on the drag and added moment of inertia coefficients were then evaluated, and empirical relationships which estimate values of these coefficients, useful to predict the unsteady behavior and magnitude of agitation torque, were presented. Furthermore, equations were developed for estimating the average and maximum power consumptions as a function of the drag and added moment of inertia coefficients. Prediction of respective power levels in AJITER by these equations was also discussed. © 2001 Society of Chemical Industry     

超重力场内气液传质强化研究进展

气液传质过程广泛存在于化学工业当中。气液传质强化技术的研究, 对缩短工艺流程、缩小设备尺寸、降低投资和运行成本等具有重要的意义。以旋转床为核心装备的超重力技术, 是气液传质过程强化的有效技术之一。经过30多年的发展, 超重力过程强化技术在基础和应用研究方面都取得了长足的进展, 特别是在受混合和传递限制的过程中得到广泛应用。本文从旋转床转子结构出发, 综述了整体旋转式、双动盘式、动静结合式等转子结构的超重力旋转床气液传质强化的研究进展和理论成果, 并展望了超重力旋转床气液强化传质的发展方向。     

变径悬臂搅拌轴临界转速的近似计算方法

针对工业上常用的变径悬臂搅拌轴,HG/T 20569中没有相应的临界转速计算方法,为找到简便的近似计算方法,使用ANSYS计算了3个算例的临界转速,并与HG/T 20569中悬臂与跨间二轴段直径相等、作用集中质量的悬臂轴的计算公式进行对比,经数据对比和理论分析,认为在计算变径悬臂搅拌轴的临界转速时,可以采用该公式,将变径轴的质量折算为当量质量来近似计算。     

旋转填料床气相压降研究进展

本文概要介绍了旋转填料床的工作原理及结构组成 ,着重讨论了旋转填料床气相压降的实验及理论研究情况 ,分析了气相压降与旋转填料床转速以及气体流量的关系