关于真空泵基础压力与罗茨真空泵特征性能指标的探讨

本文阐述了真空泵的极限压力与基础压力两者的概念和关系,对国际标准ISO21360-1:2012中有关基础压力的条款做了详细的解读。对影响中真空罗茨泵抽气性能的特性指标进行了分析,给出了用罗茨泵零流量压缩比K0和最大允许压差作为罗茨真空泵的抽气性能指标的合理性,建议选择罗茨泵零流量压缩比K0作为罗茨泵抽气能力的主要考核指标之一,将最大允许压差作为罗茨泵的辅助考核指标。     

罗茨真空泵特性指标及测试方法研究

本文分析阐明了罗茨泵的特征性能为漏率、零流量压缩比、最大容许压差和噪声。提出了新概念—基础压力的定义:即泵按规定条件工作,在不引入气体的情况下,标准测试罩内趋向稳定的压力。并建议以漏率取代极限压力作为罗茨泵的性能考核指标,使罗茨泵性能的测量方法更接近、更符合实际运行状态。根据实验数据,提出了对零流量压缩比测量装置中的前级管路规定的改进,对最大容许压差测量方法提出了修改以及对噪声的测量方法提出一些新的见解。     

罗茨真空泵机组抽气速率分析

罗茨真空泵机组因配用前级泵不同和所处工作压力范围的差异，相应其抽气速率变化较大，设计中应根据具体工况条件及真空系统使用要求，力求使罗茨真空泵机组体现好的适用性和经济性。     

论罗茨真空泵的基础压力和漏率

基础压力是容积真空泵的特征性能指标,但作为容积泵一员的中真空罗茨真空泵却不是,它的性能在很大程度上依赖、取决于前级真空泵和测试条件,只有漏率才是罗茨真空泵的特征性能指标。本文分析了极限压力、基础压力和漏率三者之间的关系,着重指出,漏率的测量与前级泵无关,也基本上不受环境温度的影响,应取代极限压力(基础压力)作为中真空罗茨真空泵的特征性能指标。     

罗茨真空泵性能考核指标——抽速和零流量压缩比的探讨

罗茨泵以抽速作为主性能考核指标不够确定，它不能真实反映罗茨泵的质量水平，建议以零流量压缩比作为考核罗茨泵抽气能力的性能指标。     

真空压力浸漆设备的真空和制冷系统的设计与计算

真空压力浸漆是真空压力浸渍技术应用之一.首先以浸漆罐的真空系统为例.比较了国内外的几种方案.认为利用国内产品组成的真空系统。其性能可达国外同类真空系统水平.对要求工作真空度为13.3帕.极限真空为6.65帕.抽空时间不得大于45分钟的真空系统.选择罗茨一滑阀泵和罗茨一水环泵机组.并对主泵.前级泵、抽气时间等分别进行了计算.最后从制冷剂与载冷剂选择.保温层厚度确定.冷负荷计算方面介绍了制冷系统的设计与计算.指出真空压力浸渍设备的真空系统和制冷系统的国产化是可行的。     

高压差罗茨泵组合抽气系统在大型减压蒸馏深拔装置的应用

与蒸汽喷射真空泵抽气系统相比,罗茨真空泵组合抽气系统具有启动快、节能效果明显等特点,正在被越来越多的减压蒸馏装置所采用。本文介绍了一种高压差罗茨泵组合抽气系统在大型减压蒸馏深拔装置上的应用,详细说明了该系统的结构组成、控制原理、性能参数及一些关键技术问题的解决方案。     

双级气冷罗茨泵在火电机组应用中的常见问题分析和处理

某电厂660MW机组采用双级气冷罗茨泵对真空系统进行了节能改造,双级气冷罗茨泵在运行中出现了泵体温度过高和凝汽器真空度不达标的问题,对机组安全经济运行产生了不良影响。采用观察分析和试验的方法查找导致泵体温度高和真空度不达标的原因,发现了罗茨泵前级冷却器和凝汽器抽真空母管处的积水现象,积水堵塞了抽气管路导致气路不畅,最终引起罗茨泵泵体温度高和凝汽器真空度不达标。经技术改造消除了两处积水现象,进而解决了罗茨泵泵体温度高和真空系统真空不达标的问题。     

径向流涡轮分子真空泵

介绍了用于扩散泵低压端双级径向流分子泵详细结构、性能预示及性能测量。性能预示的基础是自由分子流和扩散反射的概念。就现有设计所采用的叶片与环的厚度值来讲，我们认为必须考虑到这些厚度对于泵性能的影响。预示了压强比及速度系数，几乎与转子速度成指数关系并取决于前级泵抽速及气体载荷的程度。 这次研制的泵，转子转速每分钟为３４００转，预示着它的抽速大约为作为前级泵的扩散泵对于氮和空气的抽速的１４及１０倍。预示的性能大体上在实验误差范围内与测得的性能是一致的。 如果人们想在较高的流率下设计适度的压强比，为了（ａ）对于给定的系统医强来说．增加扩散泵的抽气量，（ｂ）对于给定的扩散泵抽气量来说，降低系统的压强，那么就可以在扩散泵的低压端采用径向流涡轮分子泵。     

无油超高真空系统的发展和应用

本文介绍无油超高真空系统的主抽气系之──冷阴极溅射离子泵的发展 和应用,包括泵的工作原理、结构、性能、使用和维护等,同时介绍了无油真 空系统的前级泵。     

罗茨真空泵的最大允许压差和溢流阀压差

文章分析了影响提高罗茨真空泵最大允许压差因素，提出了解决方法。介绍了带溢流阀罗茨泵的特点和溢流阀压差的试验方法，明确提出应对带溢流阀罗茨泵考核溢流阀压差。     

偏心圆弧罗茨转子型线的研究

罗茨转子作为罗茨真空泵的重要组成部件,对罗茨真空泵性能影响极大。为了解决传统渐开线型转子在渐开线与圆弧连接处存在不光滑连接点,导致泄漏加剧,运行效率下降的问题,文章采用偏心渐开线与齿顶、齿根圆弧平滑相连,提出了一种偏心渐开线型不对称转子。建立了偏心渐开线型不对称转子的几何模型,分析了转子的几何参数对面积利用率等性能的影响。结果表明：随着圆心角增大及节圆半径减小,所提出的偏心渐开线型不对称转子的面积利用率提高;与传统渐开线型转子相比,所提出的偏心渐开线型不对称转子每转排量提升了17.2%,出口流量脉动降低9.8%,出口压力脉动降低7.9%。研究内容对罗茨真空泵的发展具有重要的意义。

     

Kennfeldanalyse einer Schraubenvakuumpumpe

Operating Performance of Screw Vacuum Pumps This paper presents detailed analyses of the operating performance of a dry‐running screw vacuum pump. The characteristic parameters, suction speed and final attainable pressure ‐ which primarily define the operating performance of screw vacuum pumps ‐ are explored in experimental and theoretical investigations. Experiment and simulation in combination are used to show the correlation between the main physical and technical characteristics and the operating performance of screw vacuum pumps. This basic knowledge is essential for understanding the specific machine physics of positive displacement vacuum pumps, especially for screw vacuum pumps, and is useful in view of further design and optimization processes. The experiment covers measurements of the operating performance of the investigated isochoric screw vacuum pump working against ambient pressure. As operating parameters intake pressure (1000mbar to 10^‐3mbar) and rotor speed are varied over a wide range. The theoretical analysis of the operating performance contains simplifying models as well as simulations of the thermodynamic processing. The impact of external leakages, clearance vacuum flows and further losses on operating performance are described in detail.     

Non-contact vacuum pumps

An overview of the main methods for mathematical modeling of the working process of non-contact vacuum pumps is given. The specifics and the main stages of mathematical model development for screw, scroll, claw and Roots vacuum pumps are considered. The results of mathematical modeling of pump characteristics are presented and compared with experimental data. The mathematical modeling technique presented here can be recommended for analyzing the influence of pump geometry and operating conditions on the pump characteristics of non-contact oil-free vacuum pumps.     

Wälzkolbenpumpen mit ATEX‐Zertifizierung

ATEX‐certified Roots pumps – customer‐focussed solutions for applications in hazardous areas After the European directive ?ATEX“ that harmonizes the member states' laws relating to explosion protection had been released, the demand for vacuum pumps according to this directive has increased. This article deals with explosion proof Roots pumps and its characteristics, particularly emphasizing the importance of the overflow valve. The fact that the standard valve could not be used for ATEX‐certified Roots, in some cases, came with some disadvantages for the operation of the pump. This made it necessary to design an overflow valve for hazardous atmospheres, the development of which is explained at the end of this article.     

Abpumpverhalten von Roots‐ und Schraubenvakuumpumpen

Pump down characteristic of Roots pump combinations Combinations of roots pumps and screw type vacuum pumps are often used in industrial vacuum applications because of their high pumping capacity, their compact dimensions and their good energy efficiency. In load lock applications, the type of load control has a high influence on the evacuation time as well as on the energy efficiency of the pump combination. The operation limits of roots pumps are discussed and means to prevent an overload of the pump are introduced.     

Characterisation of a turbo-molecular pumps by a minimum of parameters

The design of complex vacuum systems including turbo-molecular pumps requires knowledge of the characteristics of the turbo-molecular pumps. Normally, such characteristics for commercially available turbo-molecular pumps are presented as graphs of pumping speed, compression ratio and so on as a function of inlet or outlet pressure. It is difficult to incorporate such information into a model for designing complex vacuum systems, especially when optimising the number of pumps, their pumping speed and choice of backing pump.Voss [Characteristics of the turbomolecular pumps. Vakuum in Forschung ung Praxis 2002;14(4)] has published fitting formulae for specific pumps as a way of describing pressure, pumping speed and compression at the inlet, by means of a number of parameters which are described in a table for each gas and throughput. These fitting formulae can be used in modelling, but the fitting parameters for an arbitrary pump are not in general available.A new approach is proposed based on ‘true zero-throughput’, which has been defined as the ratio of the probability of a gas molecule travelling from the pump inlet to the outlet to that of its travelling from the outlet to the inlet. This is different from the usually reported ‘zero-throughput’ data which are measured with zero gas injection, but not ‘zero gas load’ at the inlet (due to thermal outgassing of a measuring dome and the pump itself). Parameters in the formulae developed here are no longer simply fitting parameters, but have clear physical meaning. The dependence of the parameters for different gases may be included as a function of mass. The new formulae presented, allow us to model the performance of cascaded turbo-molecular pumps. As an example, the formalism is applied to the differential pumping stages of the KATRIN experiment [KATRIN Collaboration. KATRIN design report 2004. Forschungszentrum Karlsruhe Scientific Report # FZKA 7090, 2005].     

燃油系统旋涡泵压力脉动的控制研究

为了改善燃油泵噪声、振动、声振粗糙度(noise,vibration and harshness,NVH)性能,提高燃油泵声音品质,开展了燃油系统旋涡泵压力脉动的控制研究。采用计算流体动力学(Computational Fluid Dynamics,CFD)数值模拟方法和理论分析方法分析燃油系统微型旋涡泵的压力脉动特性,并采用随机叶片分布方法设计了2种非均布程度不同的非等距叶轮。基于CFD数值模拟结果和理论分析结果,提出一种改进的非等距叶轮设计方法。燃油泵噪声试验结果验证了该设计与控制方案的可行性。结果显示:相较于等距叶轮,随机非等距叶轮燃油泵的中高频段尖锐噪声消失,NVH性能提升;随机非等距叶轮能够显著分散叶频峰值,非均布程度的增加显著增大了随机非等距叶轮的叶频脉动幅值下降幅度。因此,采用随机叶片分布方法,有助于改善旋涡泵的压力脉动特性,对改善燃油泵的NVH性能具有重要的工程应用价值。     

叶片泵振动机理特性分析及改进设计

机械设备振动和设备组成、工作机理、工作状态等息息相关,船用常见设备如水泵、风机等由于工作机理各不相同,其振动频率特性也各不相同。通过对旋转类设备振动特征进行对比分析,分析设备主要振源及其成因,提出设备改进方向,并进行针对性改进设计,试验结果表明,取得了良好的效果。