分离机转鼓超速自增强最佳超速条件的研究

采用的最佳超速条件是否恰当直接与超转速的选择及超速自增强的效果有关。本文通过对分离机转鼓零件进行弹塑性应力分析,提出了一种超速自增强的新的最佳超速条件:使超应力参数Ky最大的超转速N_A即为最佳超转速。该条件表示转鼓在工作时弹性工作范围最大,它是最大合成工作应力最小原则的一个推广。还根据此条件确定了某分离机的最佳超转速范围。     

分离机转鼓超速自增强的变形分析

本文采用弹塑性有限元法和解析法,对分离机转鼓的主要零件进行了超速自增强的变形分析。认为,用奥氏体不锈钢等低强度钢制造的转鼓零件应按塑性准则进行强度与变形分析。提出了以某特征位置处的残余变形作为超速的控制参量。理论计算与分析表明,对用本构关系符合Ramberg—Osgood关系的奥氏体不锈钢制造的转鼓零件,超速后的残余变形具有下列规律:u~r=R[Aφ~a-B],该式可以作为起速设计的计算依据,并应用于超速工艺中。     

超应力技术用于碟式分离机转鼓及其机理的研究

本文介绍了超应力技术用于解决碟式分离机转鼓材料的机械强度和耐腐蚀性能要求的矛盾。利用弹塑性有限元计算和模型试验的结果,分析讨论了转鼓超速自增强的机理及其特殊性。认为材料的强化作用是主要的,而应力均化作用有限,不同于压力容器及叶轮的自增强。文中还对转鼓零件超速的自增强有关问题,进行了讨论,提出了一些看法。     

离心分离型碟式分离机转鼓内部流场数值模拟

针对离心分离型碟式分离机,利用ICEM CFD软件完成转鼓内部流场三维几何模型的建立和六面体网格的划分。选择Fluent软件中的Mixture多相流模型、Realizable k-ε湍流模型和SRF动区域计算模型进行数值模拟。结果表明:离心分离型碟式分离机油水两相分离效果明显,油相出口含油率达99. 96%;油相体积分数分布、压力分布和切向速度沿径向分布符合碟式分离机转鼓内部流场基本理论规律;提升转鼓转速能够显著提高分离机的分离效率,增大水相粒径在一定程度上可以提高分离效率。     

基于COSMOSWorks的碟式分离机转鼓体强度研究

介绍了碟式分离机的分离原理,并依据离心力场的基本特性,对碟式分离机中最主要的零件转鼓体进行受力分析,通过有限元分析软件COSMOSWorks对转鼓体进行静强度计算,得到转鼓体的应力水平,为转鼓体的结构优化设计提供依据。     

碟式分离机转鼓应力的有限元计算

一、前言 碟式分离机是利用离心力,进行液—波—固分离的高效设备。它在食品、油脂、发酵、环保等行业中有着广泛的用途,是许多新工艺流程不可缺少的先进装备。转鼓是碟式分离机的关键部件,它由转鼓本件、顶盖、活塞、锁紧环、碟片组等主要零件装配而成。由于转鼓工作转速高,零件自身质量引起的离心力和分离液体与操作液体的离心     

碟式分离机转鼓强度计算软件开发

转鼓是碟式分离机的关键部件之一,其结构强度是用户十分关心的问题。针对碟式分离机转鼓部件的强度问题进行了研究,提出了考虑预紧力和接触情况的应力计算分析方法,所研究的方法基于ANSYS分析软件进行二次开发来实现。最后通过算例验证了方法和程序的正确性。     

国外蝶式分离机机型现状及发展趋势

本文剖析了国外碟式分离机的机型,阐述了分离机的基本机型、转鼓组件、机壳、传动装置及自动控制系统等,并介绍了碟式分离机近来的发展。     

碟式分离机转鼓的新材料——00Cr13Ni6MoNb钢

<正> 碟式分离机由于它具有的各种优越性能,故广泛用于国民经济的各个部门,且是国内外发展较快,品种最多的一种离心分离设备,但制造分离机的关键另件;转鼓及盖的材料问题,却是国内各有关单位颇感兴趣的问题。本文将扼要介绍DPD—445型淀粉分离机转鼓及盖所用的新材料—7424钢(即00Cr13Ni 6 MoNb钢)的有关性能以及国内外分离机的转鼓用钢,作一点滴判析,供有关方面参考。     

小型风力发电机电气制动平稳性控制研究及实现

小型风力发电机目前面临的最大难题是其安全性、可靠性和制动的平稳性问题,即大风时的超速保护.本文介绍了一种当转速大于转速最值时,利用短路定子三相绕组,通过PID算法控制.不仅能够使转速可靠地降下来,而且能够实现小型风力发电机制动过程光滑而平稳的方法.控制方法简单,实现小型风力发电机平稳性制动.制动控制的核心是单片机,结构简单,制动的平稳性容易实现,经济且编程简单.     

二氧化碳压缩机超速保护系统与电液转换器的改造

尿素装置二氧化碳压缩机控制系统采用德国VOITH公司生产的E580系列电液转换器对原控制系统电液转换器进行改造,取消原飞锤式超速保护系统,选用3取2电子超速保护系统实现超速保护,同时对现场控制油路进行简化,将原来控制油系统中单个部件集成到速关控制装置中,提高了机组控制系统的控制性能及安全可靠性。     

不同历史时期耀州窑碗器型结构特征之研究

以耀州窑不同历史时期出土碗的复原图为研究对象，用扫描仪输入器型图片，并通过切片法对器型结构进行数字化，以线性回归方差分析法进行了器型数字化最佳切片数的研究。以多元统计分析法对数字化结果分析得出：唐、五代及宋代耀州窑碗样品的器型可用判别函数Rb／Rt=0．385进行辅助断代，除此，碗的底足与口径显示出明显的时代特征，是区分不同时期碗和研究碗器型结构的关键性指标。     

管式离心机固液两相流场的数值模拟

简单介绍了管式离心机的主要技术状况、不足及FLUENT软件;在简化的基础上,从单一相连续方程入手建立了管式离心机内的固、液两相流动数学模型,通过计算网格划分和边界条件的确定,用FLUENT二维数值模拟了该机内的两相流流场及随时间变化的分离状况,得出了直观的机内不同截面上的速度分布及分离颗粒的体积分布云图。模拟结果符合该机的运行规律,为进一步深入研究奠定了基础。     

Efficacy of pine oil as repellent to wildlife

Pine oil, a by-product of the pulp industry, is a feeding repellent to snowshoe hares and voles. In pen trials with snowshoe hares and field trials with voles, when given a choice between food in a pine oil-treated bowl and a control bowl, the animals fed preferentially from the control bowl. When the hares were presented with food only in a pine oil-treated bowl, two hares showed a reduced rate of food consumption and one hare did not feed at all. Pine oil contains monoterpenes which may inhibit microbial symbionts in the digestive tracts of hares and voles. The repellent action of pine oil is likely based on this interference of digestive processes, and it is of adaptive advantage for cecal digestors to avoid it. Pine oil has potential as a commercial repellent for snowshoe hares and voles.     

坐便器参数化CAD系统的研究与开发

以UG为平台,VC 为开发工具,根据典型陶瓷产品—坐便器的结构特点,分析了该类产品的形状特征,将其分解为水包、坐圈、水箱、进水通道、排污管和底座等组成单元。采用UG通用的建模命令对产品进行不同方式的多次建模,找出了较好的建模顺序和方法,开发了坐便器参数化CAD系统。该系统开发采用向导设计模式,结合知识库工程,建立了坐便器结构和制造工艺参数等标准和经验数据库。系统运行时,设计者可按照系统提供的设计向导,快捷合理地选择设计参数进行产品的造型设计。     

Studies on the microstructure of the black-glazed bowl sherds excavated from the Jian kiln site of ancient China

The Jian kiln, located in present-day Jianyang county of Fujian province, mainly produced black-glazed tea bowls. Jian tea bowl was used as a utensil for tea tasting and was greatly appreciated by emperor Huizong of the Northern Song dynasty. The black glaze of Jian bowl was sometimes marked with streaks or spots, usually called “hare's fur” or “oil spot”, which are the crystalline markings of iron oxide precipitated during firing in the dragon kiln. In this study, black-glazed Jian bowl sherds excavated from the late Northern Song strata of Luhuaping and Daluhoumen Jian kiln sites were adopted as test samples. Based on the physico-chemical foundation for the formation of glaze microstructure, the correlation among composition, microstructure, and visual appearance has been investigated by means of energy-dispersive X-ray fluorescence, X-ray diffraction, and field emission electron microscopy. For the first time, the study provides realizing proofs for two kinds of microstructural forming mechanics.     

Cleanabilty study of a Scraped Surface Heat Exchanger

Scraped Surface Heat Exchangers (Contherm SSHE model 6 × 3) are widely used industrially. In this kind of heat exchanger, the inlet and the outlet are difficult to clean due to their particular geometry and the presence of seals. A specific study was conducted on the inlet bowl of a SSHE, whose design has been optimized by the manufacturer in order to minimize risk of deposition by eliminating hydrodynamic dead zones. For this purpose, measurements of wall shear stress were made by an electrochemical method, for different hydrodynamic conditions. On the other hand, cleanability measurements were also performed. The bowl geometry tested presented no dead zones. However, the available space for flow significantly reduces the Reynolds number and turbulence intensity. As a consequence, three areas of increasing contamination appeared throughout the bowl due to the low mean and fluctuating shear stress values. The use of a pulsating flow increases these fluctuations, and thereby reduces the residual contamination.     

Preparation of M@BiFeO3 Nanocomposites (M = Ag,Au) Bowl Arrays with Enhanced Visible Light Photocatalytic Activity

High surface area BiFeO₃ (BFO) bowl arrays photocatalyst loaded with different size noble metal nanoparticles were successfully prepared by combining templates method and thermal evaporation followed by heating. The structural and optical properties of the BiFeO₃ bowl arrays and the composite M@BFO bowl arrays (M = Ag, Au) were comparatively characterized. The composite M@BFO bowl arrays showed much higher photocatalytic performance than the pure BFO bowl arrays. The enhanced photocatalytic property of the composite structure could be ascribed to the enhanced near‐field amplitudes of localized surface plasmon of the noble metal nanoparticles which boost the separation of electron–hole pairs and the transfer mechanism of electrons.     

W1-1000卧式曲面锥篮离心机的设计和应用

以过滤碳酸氢铵悬浮液的WI-1000曲面锥篮型与WI-500锥篮型离心机进行比较,介绍WI-1000卧式曲面锥篮离心机的设计和试验,证明该机型是具有开发前景的新设备。     

Measurement of the velocity field and frictional properties of wet masses in a high shear mixer

In order to develop predictive process models and to enhance process understanding in high shear granulation, there is an ongoing search for non-intrusive methods for measuring the wet mass velocities in the mixer. In this study, a high speed CCD camera is used in combination with software for particle image velocimetry (PIV) calculations to obtain information about the wet mass velocities. The focus has been on obtaining good spatial and angular resolution for the velocities along the glass bowl wall. In a Jenike shear cell, both internal and wall frictional properties have been measured and together with velocity data, this information is used for prediction of the impeller torque. It has been shown that the near wall velocities are strongly dependent on the coefficient of wall friction, which decreases during liquid addition. The decrease in the coefficient of wall friction results in increased wet mass velocities close to the bowl wall. It is also found that the wet mass velocity has a strong angular dependence, resulting in a high frequency pulsing bed behaviour which cannot be detected by visual inspection. The predictive impeller torque model developed by Knight et al. [2001. Prediction of impeller torque in high shear powder mixers. Chemical Engineering Science 56, 4457-4471] has been generalized to account for cohesive materials and with frictional and velocity data, the level of the impeller torque is well predicted. However, the model is based on crude assumptions regarding the velocity distribution and hence, it cannot capture the dynamics in the measured torque curve satisfactorily.