A tool for mass transfer evaluation in packed-bed columns for chemical engineering students

This paper presents a Microsoft Excel tool to calculate liquid-gas mass transfer coefficients in packed towers to support numerical design activities in the courses of Unit Operations for Industrial Process and Sustainable Process Design for the Master’s degree in Chemical Engineering of the University of Naples Federico II (Italy).The Mass Transfer Solver Tool (MT Solver Tool) uses several available models to estimate, separately, the values of liquid and gas mass-transfer coefficients and the wet surface area for 144 random and structured packings of interest for absorption/stripping and distillation processes. In addition, a separate spreadsheet can be used in a user-defined mode, to evaluate the mass transfer coefficients with new packing types or to interpret experimental data when the geometrical and physical characteristics of the packing are known. Eventually, the tool is supplied with a data library, where packing geometry and model fitting parameters can be retrieved.The software is aimed to support students and educators in the Unit Operations for Industrial Process and Sustainable Process Design courses. In particular, this is meant to be an example on how the accuracy of design algorithms adopted in unit operation processes is affected by the use of the underpinning correlations for mass transfer rate or pressure drops. Besides, this is aimed to encourage comparison of different correlations when exact field data are not available. Besides, chemical engineers and researchers interested in packed columns design and modelling data may also benefit from the utilization of the software. The MT Solver Tool was introduced to students in a dedicated tutorial lesson after lecturers on packed column design algorithms for distillation, absorption and stripping. Most of the students of the course participated to a group training aimed to simulate the design of an absorption column supported by the MT Solver Tool providing feedback on its application.After the training, an anonymous survey was proposed to the students to monitor the approval rating of the proposed activity and the use of the MT Solver Tool software to support numerical calculations.     

分析铁路改良粉细砂填料应用性能试验

在设计铁路路基的填料时,最常出现的是在进行铁路建设的地方就地取材。在以粉细砂为主的地区通常会选择用粉细砂作为铁路的填料,在所有的填料中,粉细砂填料属于C组类型填料,但是因为两个方面的原因需要对其进行一定的改良,一方面是因为粉细砂的粒径比较单一、级配不好,K30不能够满足规范标准的要求;另一方面则是因为大型机械不能够进行施工。本文通过掺入不同体积A、B组砾砂填料到粉细砂填料中进行试验,结果显示这种操作可以在不同程度上提高K30的值,从而在达到相关设计要求的同时解决施工方面的难题。     

基于ABAQUS的变截面橡胶密封条热应力与密封性分析

研究用于发动机油气分离器的乙烯丙烯酸酯橡胶密封胶条在不同温度下的强度和密封性能。借助于大型有限元分析软件ABAQUS建立橡胶密封胶条与配合壳体的有限元模型,采用Mooney-Rivlin模型,对不同温度下的密封胶条进行热应力计算分析,得到橡胶密封胶条在不同温度下的Von Mises应力、压缩率、接触应力和接触宽度。结果表明:随着温度的升高,密封胶条的Von Mises应力和密封胶条与壳体连续接触面上的接触应力逐渐增加,接触宽度基本不变,密封条的压缩率逐渐减小;密封胶条的Von Mises应力远小于橡胶材料的拉伸强度,满足强度要求;密封胶条连续接触面上的接触应力始终大于油气分离器的工作压力且接触宽度符合要求,橡胶密封胶条满足密封条件。     

退火温度对6.5%Si极薄带织构及磁性能的影响

采用单辊甩带法制备了厚度为0.03 mm的6.5%Si极薄带,并在真空炉中进行了880 ℃和920 ℃的退火处理。利用XRD和EBSD研究了其在退火后的宏观和微观织构演变规律。结果表明:经单辊甩带制得的6.5%Si极薄带织构主要由{001}<100>立方织构、{110}<001> Goss织构和{112}<111>织构组成。随着退火温度的升高,λ纤维仍占主导地位,且晶粒尺寸逐渐增大。特别是在920 ℃退火时,{001}<120>和{001}<100>晶粒的尺寸优势逐渐增大,不利织构{111}<110>和{111}<112>逐渐减弱,且最终的磁感应强度B₅₀=1.644 T,铁损耗P_10/400=5.896 W/kg。     

Feedforward control of the transverse strip profile in hot-dip galvanizing lines

Hot-dip galvanizing is a standard technology to produce coated steel strips. The primary objective of the galvanizing process is to establish a homogeneous zinc layer with a defined thickness. One condition to achieve this objective is a uniform transverse distance between the strip and the gas wiping dies, which blow off excessive liquid zinc. Therefore, a flat strip profile at the gas wiping dies is required. However, strips processed in such plants often exhibit residual curvatures which entail unknown flatness defects of the strip. Such flatness defects cause non-uniform air gaps and hence an inhomogeneous zinc coating thickness. Modern hot-dip galvanizing lines often use electromagnets to control the transverse strip profile near the gas wiping dies. Typically, the control algorithms ensure a flat strip profile at the electromagnets because the sensors for the transverse strip displacement are also located at this position and it is unfeasible to mount displacement sensors directly at the gas wiping dies. This brings along that in general a flatness defect remains at the gas wiping dies, which in turn entails a suboptimal coating.In this paper, a model-based method for a feedforward control of the strip profile at the position of the gas wiping dies is developed. This method is based on a plate model of the axially moving strip that takes into account the flatness defects in the strip. First, an estimator of the flatness defects is developed and validated for various test strips and settings of the plant. Using the validated mathematical model, a simulation study is performed to compare the state-of-the-art control approach (flat strip profile at the electromagnets) with the optimization-based feedforward controller (flat strip profile at the gas wiping dies) proposed in this paper. Moreover, the influence of the distance between the gas wiping dies and the electromagnets is investigated in detail.     

往复活塞式压缩机活塞杆温度高故障分析及改造

针对2台2D40型空气压缩机在实际试机过程中,活塞杆温度过高,导致连锁报警,压缩机不能正常工作的问题进行了详细的故障原因分析;对压缩机技术性能参数进行介绍;对压缩机的损伤情况进行说明并找到改造方案,解决机组运行中活塞杆温度过高的问题,从而提高机组的运行效率,使机组运行安全、稳定。     

改良森吉米尔法退火炉中带钢的氧化研究

总结了带钢经过改良森吉米尔退火炉后的4种氧化状态,通过现场实际生产经验的总结和数据积累,分析了带钢产生表面氧化的关键因素,指出了实际操作中应该注意的事项,为以后的设计调试及生产提供了参考。     

冷轧带钢切边圆盘剪装置的优化与改进

针对冷轧带钢切边后产生的边部梗压印缺陷,结合切边圆盘剪的剪切原理,设计了一种圆盘剪复合衬套,其采用100Cr钢质内圈和MC尼龙外圈复合结构组成,取代原纯钢质衬套,使圆盘剪在剪切带钢过程中由钢性接触转变为弹性接触,从而避免了带钢边部梗压印缺陷的产生,提高了切边质量与剪切里程数,降低了圆盘剪备件成本,提高了生产效率。     

35克素牛排单片重量控制方案探究

目的探究制定公司畅销产品大豆蛋白类食品35克素牛排的重量控制方案。方法研发人员通过查阅相关资料、采集生产与管理人员的意见、跟踪生产全程等手段获取实验方向,并通过小实验改变工艺条件和生产试验进一步验证工艺条件,探寻出了35克素牛排在生产过程中的重量变化规律、重量不稳定的主要原因及改进措施。结果 35克素牛排的单片重量与产品卤制工序呈影响极显著,与原材料重量、油炸工序差异显著。结论原材料控制在11克以上,油炸时间2分钟,最佳卤制时间10分钟,产品的单片重量合格率提高到90%以上。