苯乙烯装置中氢压机吸气阀的断裂原因

某苯乙烯装置中氢压机四级气缸东侧吸气阀在运行中发现其阀座密封面有部分区域断裂。通过宏观分析、低倍分析、化学成分分析、金相检验、硬度测试和扫描电镜分析等方法,对阀座密封面断裂的原因进行了分析,并提出了相应的措施。结果表明:阀座因热处理工艺不当,在阀座上表面外圈台阶部分金属损伤处形成疲劳裂纹,并在工作过程中向两端不断扩展,在交变载荷的作用下阀片内的弹簧断裂,导致裂纹处应力更加集中和阀座承载能力下降,加快阀座疲劳裂纹的扩展,最终导致阀座密封面部分区域断裂损伤。     

氮气压缩机气阀阀座断裂原因分析及改进

为了满足当下工作的需要,进行氮气压缩机气阀阀座断裂原因的分析是必要的,这涉及到座断原因及其改造模块的分析,从而进行氮气压缩机网状气阀阀座问题的解决,保证其气阀的工作环境的优化,保证其材质模块、阀座模块等的开展。这需要应用到氮气压缩机的各个部件工作模块,进行其阀座及其相关部件的强度分析,从而满足当下工作的需要,积极做好相关的验算工作,保证阀座高度的提升,使其满足我国相关法律法规的需要,实现危险截面的整体安全性。本文介绍了氮气压缩机网状气阀阀座出现断裂的现象,分别从气阀的工作环境、材质和阀座强度3个方面进行了分析,在确定阀座Ⅱ—Ⅱ危险截面弯曲应力不足导致阀座断裂后,增加了阀座高度并重新进行验算,使结果符合Ⅱ-Ⅱ危险截面安全的要求。     

超高压平板闸阀的双阀座密封分析

该文分析了超高压平板闸阀中双阀座的密封原理以及密封圈预紧力对密封效果的影响。利用有限元分析软件建立了双阀座密封结构的二维轴对称模型,对阀座的非金属密封进行了性能分析。分析了"O"形密封圈在不同的压缩率的情况下的Mises应力、密封面最大接触应力以及密封面接触面积。综合考虑了影响密封效果和密封圈寿命的因素后选取了线径3.75mm的密封圈。     

23-300型空分设备充氧台阀门的改装

我厂氧气站的23—300型空分设备,充氧气台原来使用的高压氧气截断阀(在集合管上左右各一个),原结构如图1所示。锥形阀心用不銹钢制造,阀座由黄铜料制造。由于开启次数频繁,阀座磨损较快,往     

快关蝶阀密封副瞬态热及碰撞冲击研究

为准确评估动态升温过程中结构是否安全,基于经典赫兹接触理论、旋转动力学以及碰撞冲击理论,采用数值仿真方法对快关蝶阀分别进行瞬态热-结构耦合分析与瞬态动力学分析研究,对比研究了不同升温速率、不同关闭时间及不同密封面宽度对快关蝶阀结构强度及阀座密封性能的影响规律.研究表明:快关蝶阀的最终热应力和阀座密封面接触压力均随着升温...     

北京北高阀门有限公司BG200系列蝶阀

结构简单，通用互换性好．价格低廉。阀杆密封不易变形从而避免了通常的阀杆泄漏现象。整体支撑性好．稳定、牢固。阀座橡胶用量少．膨胀的潜在影响小，容易将扭矩值控制在适当的范围内。采用两截式阀杆无销连接，结构简单紧凑．维修拆卸极为方便。碟板具有自动对中功能，实现了蝶板与阀座小过盈合量配合。     

调节阀阀座传统结构的改进

通过对调节阀阀座传统螺纹结构在实际生产和应用中存在的一些问题的分析，提出了一种新型的改进方案，即新型无螺纹结构，该结构具有传统结构诸多无法比拟的优越性，发展前景广阔，有推广价值。     

基于冲蚀磨损理论的新型内防喷器阀座锥角研究

针对现有内防喷器失效率高等不足，提出一种结构新颖且密封可靠的自旋合式锥形密封内防喷器。对该新型内防喷器的阀座锥角进行了力学分析，并采用MATLAB对阀座锥角进行了优化。基于理论分析得到的结论，采用CFD（computational fluid dynamics，计算流体动力学）方法（标准k-ε湍流模型及Tabakoff-Grant冲蚀模型）及ANSYS CFX软件，对该新型内防喷器在不同钻井液流量及不同阀座锥角下的流场进行数值模拟分析，仿真结果表明容易发生冲蚀磨损的部位主要集中在上下阀座流道边缘及下部管壁处。通过对比多组仿真数据，提出了该新型内防喷器上下阀座的最优锥角为25°，并采用ANSYS Workbench静力学分析软件模拟了井喷时上下阀座密封锥面的接触应力分布，验证了冲蚀仿真分析得出的最优锥角的结论。样机试制后进行了密封性实验以验证其可靠性，结果表明该新型内防喷器无泄漏，满足密封性要求。研究结论为内防喷器的设计与改进提供了重要的理论依据，对油田生产设备的安全升级有重要意义。     

锥阀和锥阀座失效分析

采用显微分析方法对锥阀和锥阀座的失效进行了分析。结果表明，锥阀和锥阀座的失产属接触疲劳失效。锥阀渗钒层厚度不匀及锥阀座氮化组织不正常，是导致失效的主要原因。     

四通换向阀中采用新型材料的节能效果

为了降低四通换向阀传热损失导致的热泵空调系统的性能损失,提出采用低导热系数的阀座材料替代原阀座材料的方案,并结合实验和系统仿真分析了该方案的实际节能效果。研究结果表明:现有典型四通换向阀的传热损失不可忽略;考虑到结构设计和加工工艺等影响因素,采用低导热系数阀座材料是降低四通阀传热损失较为可行的方案;阀座材料导热系数由常见的110 W/(m.K)降为60 W/(m.K)后,四通阀传热损失减小21%,热泵系统COP提高0.4%。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。