焦化加热炉炉管失效原因分析

通过对某炼油厂焦化炉失效炉管的材料成分，力学性能，显微组织等的分析，确定了其失效模式为高温硫腐蚀以及氧化腐蚀。加质变炉炉管内外壁结焦层硫含量超标，在烧焦时，局部炉管过烯，发生膨胀变形，使强度下降，最终导致炉管失效，提出了预防失效的措施。     

焦化炉注水炉管腐蚀失效分析

通过对炼油厂焦化车间焦化炉注水炉管的材料成分、燃料和烟气组分、过剩空气量及金相组织和外表面垢样组分分析，以及温度场和流场烟气中的SO3的浓度场等综合分析，确定了其失效模式是硫酸露点腐蚀与烟气冲刷腐蚀共同作用的结果。注水炉管低温段以及高温段管壁外表面的复盐腐蚀形貌本质属性为高温硫腐蚀以及碱金属腐蚀。提出了预防措施。     

石油化工过程装备的环烷酸腐蚀与防护

伴随原油劣质化,石油化工过程装备的环烷酸腐蚀日益严重。在探讨环烷酸腐蚀机理的基础上,就酸值、温度、流速及材质等可控因素对环烷酸腐蚀的影响规律及环烷酸腐蚀的研究手段进行论述,针对环烷酸腐蚀现状,主要采用高温部位材质升级、材料表面强化、降低酸值、添加缓蚀剂、控制流速和流态等措施进行防腐蚀,明确未来的工作重点在于多因素耦合试验研究和典型材料耐环烷酸腐蚀的模拟试验研究。     

酸性条件下几种锅炉炉管钢腐蚀性能分析

研究了几种锅炉炉管钢在ｐＨ＝３的Ｈ２ＳＯ４溶液中腐蚀速率的差异。电化学测试结果表明：炉管钢的腐蚀速率与钢中合金元素的种类和含量有一定关系;含铬、钼量较高的钢种腐蚀速率较低。由此可见,铬元素是抑制炉管钢在酸性介质中发生腐蚀的最主要的合金元素,其他元素如钼、镍等对炉管钢的腐蚀性能也有重要影响。     

炼油装置常用材质高温环烷酸腐蚀的主要影响因素及腐蚀行为

高温环烷酸腐蚀是高酸值原油加工装置的主要破坏形式,温度、总酸值、流速、材质等均是环烷酸腐蚀的影响因素。以炼化装置常用的304,316L不锈钢和Cr5Mo钢为研究对象,采用高温高压反应釜以正交试验方法研究了其在多因素耦合作用下各因素的影响权重,明确各材料的腐蚀破坏风险。结果表明:高温环烷酸环境中,Cr5Mo耐蚀性最差,腐蚀速率是2种不锈钢的10倍以上,腐蚀破坏风险最高;316L不锈钢耐蚀性最好,其腐蚀速率较低且不随酸值和流速增大而增大;影响Cr5Mo钢高温环烷酸腐蚀速率的因素从大到小顺序依次为流速、温度和酸值:影响304不锈钢的为流速、酸值和温度;酸值是影响316L不锈钢腐蚀破坏的最主要因素;3种材料均表现为点蚀,304和Cr5Mo更为严重,在装置未进行材质升级前应监护使用。     

某连续催化重整装置加热炉炉管开裂原因分析

某连续催化重整装置中反应器上游加热炉的炉管,在服役11a后产生裂纹引发开裂和泄漏.通过对该炉管的化学成分、室温拉伸性能、高温拉伸性能、金相组织、硬度、断口形貌和腐蚀产物的分析查找开裂原因.结果 表明:该炉管的失效为尘化腐蚀所致,炉管内壁渗碳,外壁发生氧化,高温力学性能降低较为明显.     

20G低碳钢的高温环烷酸腐蚀行为

使用高温高流速环烷酸腐蚀模拟装置对20G低碳钢在不同温度和冲刷角下的环烷酸腐蚀行为进行了研究,结果表明:温度和冲刷角对20G低碳钢的环烷酸腐蚀行为有显著影响;冲刷角对腐蚀速率的影响与温度及流速有关,腐蚀速率在280～320℃达到峰值,超过320℃腐蚀速率随温度升高呈下降趋势。20G钢的腐蚀形貌分析表明:在环烷酸腐蚀时20G钢中的珠光体优先发生溶解,在珠光体腐蚀后再由晶界向晶内腐蚀铁素体。     

2种钢在高温高浓度环烷酸中的腐蚀行为与规律

环烷酸含量及其温度是影响石油炼制设备腐蚀的主要因素,过去对其研究报道较少。采用高温反应釜中的挂片失重试验和表面腐蚀形貌微观分析,研究了20钢和321不锈钢在高温高浓度环烷酸中的腐蚀行为。结果表明,随着温度的升高,20钢和321不锈钢的腐蚀速率均先增大后减小,260℃以下反应速率主要受活化反应控制,280℃以上表面吸附成为控制步骤,260~280℃为混合控制;随环烷酸浓度的增加,20钢和321不锈钢的腐蚀速率增大;在环烷酸浓度低于2%时,20钢的腐蚀速率和环烷酸浓度为幂函数关系;当环烷酸浓度超过2%时,两者之间为线性关系。当环烷酸浓度低于3%时,321不锈钢基本不发生腐蚀;当环烷酸浓度超过3%时,腐蚀速率和环烷酸浓度为线性关系。在相同的条件下,321不锈钢的耐蚀性远优于20钢。     

新型环烷酸腐蚀动态模拟试验装置的研制

鉴于环烷酸腐蚀在炼油行业中的重要性和普遍性以及模拟试验难度大,研制了具有远程、安全、快捷、直观特性的新型环烷酸腐蚀动态模拟试验装置.该装置由循环回路系统、控温系统、PLC控制系统及电脑监控系统组成,实现了温度、流速、冲蚀角度、材料、油品种类、缓蚀剂等对环烷酸腐蚀影响等变量的交叉控制,有助于研究材料的高温环烷酸腐蚀行为;尤其是试样室的设计,实现了与实际工程极为相似的高流速汽-液双相冲刷流程,可为炼油行业的选材提供重要参考依据,具有很强的模拟性和实用性.同时,有效地避免了试验过程中油品的结焦问题.     

制氢转化炉管材HP40Nb的失效分析

某石化公司制氢转化炉炉管在运行不到40 000 h后突然破裂起火,宏观检测、表面探伤,力学性能测试,能谱、金相、电镜、X射线、应力等分析表明:炉管材料晶界碳化物过多以及疏松空洞的存在削弱了韧性,产生了较多的微观裂纹,加上管外保温材料中存在较多的Na ,Cl,K ,Mg2 ,Ca2 ,导致下猪尾管到下支耳之间应力较大部位发生应力腐蚀开裂,58号炉管首先开裂泄漏起火,其他炉管在外部火焰烘烤下短时高温损伤、变形鼓包直至开裂.针对失效原因提出了今后使用过程中应采取的防护措施.     

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.     

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.     

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.     

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)。