氯乙烯合成控制方案的优化

介绍了反应温度、催化剂活性、原料配比、原料纯度、空间流速对氯乙烯合成反应的影响情况;对氯乙烯转化控制方案进行了优化,确定了一组和二组转化器数量分配比例,建立了流量控制模型,并给出了转化器流量调节方法。     

己二酸生产中沸腾床干燥和气流干燥工艺性能比较

在目前己二酸生产中,用于固体物料干燥的代表性工艺是气流式及沸腾床式2种,对2种T艺在己二酸干燥中应用进行了综合性比较。     

磷化加热系统操作应注意的事项

由于磷化槽液温度达不到工艺要求,致使车身经磷化处理后表面生成的磷化膜达不到质量要求,严重影响车身涂装的内在质量,笔者通过对磷化加热系统的现场调查,结合热传递原理及其影响因素的综合分析,认为根本原因在于板式换热器内部磷化槽液流速太慢和流体温差过大所致,调整了磷化加热系统的操作方法解决了该问题,并提出了系统操作时应注意的事项。     

生物栅-复合人工湿地系统对黑臭河水的中试处理

针对黑臭河水溶解氧极低、有机物污染重的特点,充分利用生物栅技术和人工湿地技术组合而成生物栅-复合人工湿地系统(BFG-IVCWs),来净化黑臭河水降低COD等污染物质。试验结果表明:软性填料槽对COD的去除率为30%~40%,人工湿地对COD的去除率保持在45%,梭鱼草及蜂巢石对COD去除效果明显。该系统运行期间TP去除率为58.13%~83.25%,对TN去除效果初期较好,达到58.14%。     

气流床气化低阶煤的脱水提质预处理

褐煤、长焰煤等高含水低阶煤,无法直接用于水煤浆和粉煤气流床气化。概述了目前国内外开发的低阶煤低温蒸发脱水和干燥提质,低阶煤液态脱水提质,转化提质等方法。适用于粉煤气化的预处理关键是脱水;适用于水煤浆气化的预处理关键是提质,以提高煤表面结构的疏水性,降低干燥后煤的水分回吸平衡,制备高浓度煤浆。     

基于Newton-Raphson法的多效顺流蒸发系统的模拟

建立了普通、复杂顺流蒸发系统的数学模型,采用Newton-Raphson法求解,应用面向对象的Pascal语言编制了该算法的计算程序,可对二至七效常规和复杂并流蒸发系统进行模拟计算。以蔗糖溶液为例,对三效并流的5种流程进行了计算和比较,结果表明将各效冷凝液全部用于预热原料的多效蒸发流程能耗最低,蒸发器面积最小。     

Drop rise velocities and fluid dynamic behavior in standard test systems for liquid/liquid extraction—experimental and numerical investigations

The fluid dynamic behavior of single organic droplets rising in a quiescent ambient liquid is investigated experimentally and numerically. Three standard test systems for liquid/liquid extraction recommended by the European Federation of Chemical Engineering (EFCE) but without the respective transfer component have been chosen for the investigations: toluene/water, n-butyl acetate/water, and n-butanol/water, representing systems with high, medium, and low interfacial tension. Simulations are performed using the academic code Navier, which features a sharp interface representation and a variational formulation of the curvature. The validity of both correlations and the results obtained by dynamic numerical simulation is discussed in terms of terminal rise velocity, aspect ratio, and the onset of shape oscillation. The numerical results show excellent agreement with experiments in all three test systems, and with simulations in the n-butanol/water system published recently by Bertakis et al. (2010). The presented numerical method is applicable for a wide range of interfacial tension, whereas the investigated correlations lose accuracy with decreasing interfacial tension.     

The effects of air and particle density difference on segregation of powder mixtures during die filling

Segregation of mono-disperse binary mixtures with different particle densities during die filling in the presence of air was numerically analysed using a coupled discrete element method (DEM) and computational fluid dynamics (CFD) approach. Die filling with powders of different particle density ratios (i.e. the ratio of the heavy particles to the light particles) at various shoe speeds was simulated, in order to explore the effects of air and particle density difference on segregation. For die filling from a stationary shoe, the air can induce significant segregation by hindering the deposition of light particles (i.e., air-sensitive particles). As the particle density ratio increases, the light particles are deposited into the die at even lower speeds compared with the heavy ones due to the effect of air drag, resulting in an increase in the degree of segregation. For die filling with a moving shoe, segregation occurs due to different post-collisional velocities resulting from different particle inertia; and the degree of segregation increases as the particle density ratio increases due to the increasing difference in particle inertia. It is found that, as the shoe velocity increases, the powder flow pattern changes from nose flow dominated to bulk flow dominated and the degree of segregation generally decreases. The effect of air is limited for nose flow dominated die filling because the air can easily evacuate through the gap between the die walls and flowing powder stream. When bulk flow dominates in die filling, the air can be entrapped in the die, which has a significant impact on the powder flow and segregation behaviours. Finally, the effect of interparticle friction on segregation was investigated.     

Rapid quenching by supersonic expansion and injection of water

Gaseous components or gasborne particles in flows are often sensitive to mid range temperatures, whereby unintended side products or aggregated particles develop during cooling processes. Supersonic quenching combines high gasdynamic cooling rates of dT/dt<−10⁶ K/s with a total enthalpy reduction through evaporation of an injected liquid. In this manner the residence time at critical temperatures is minimized. Up to now there are no publications covering this particular application. Preliminary test results regarding the massive water injection into a supersonic laval nozzle flow are presented as well as the developed supersonic quench concept and corresponding design rules. Essential is the suppression of an anew temperature rise downstream of the supersonic domain when the gas is compressed and decelerated again. Therefore liquid injection into the supersonic domain and its partial evaporation within it is a key feature. Despite the massive water injection the gas flow must remain in a supersonic regime. In addition to water injection from the wall a moveable slender cone equipped with water jets is extending into the divergent nozzle from the exit to enhance the coverage of the cross-sectional area with dispersed water. Presented experimental results in form of pressure and temperature profiles prove the functional efficiency of the supersonic quench. Pressure profiles attest the supersonic conditions downstream of the water injection and define the supersonic domain length. Two dimensional temperature plots demonstrate the sufficient water distribution, the suppression of hot subsonic zones and the total evaporation of the injected water within the quench domain. Applied to “Gasdynamically induced nanoparticle synthesis” spherical non-aggregated nanoparticles are obtained.     

Experimental study of mass transfer in a dense bubble swarm

We consider the liquid-side mass transfer coefficient k_L in a dense bubble swarm for a wide range of gas volume fraction (0.45%≤α_G≤16.5%). The study is performed for an air–water system in a square column. Bubble size, shape and velocity have been measured for different gas flow rates by means of a high speed camera. Gas volume fraction and bubble velocity have also been measured by a dual-tip optical probe. Both of these measurements show that the bubble vertical velocity decreases when increasing α_G in agreement with previous investigations. The mass transfer is measured from the time evolution of the dissolved oxygen concentration, which is obtained by the gassing-out method. The mass transfer coefficient is found to be very close to that of a single bubble provided the bubble Reynolds number is based on the average equivalent diameter 〈d_eq〉 and the vertical slip velocity 〈V_z〉.