600MW汽轮机叶片断裂事故分析

分析了北仑发电厂２号汽轮机中压第９级动叶片的断裂原因，提出了造成叶片断裂事故的３个主要原因是由于轮系“三重点”共振、围带结构设计不合理、销钉与销钉孔加工装配质量欠佳，并对改进后的叶片结构和振动特性进行了分析。     

大型汽轮机低压次末级动叶片优化前后典型故障原因分析

某型汽轮机低压次末级动叶片优化前后均出现了次叶片断裂和裂纹故障问题,为了查明该型叶片故障原因以防止后续再次发生,对叶片故障情况、运行参数及历史记录等进行检查,对部分故障叶片材料和断口进行理化检验分析,并采用有限元法对优化前后叶片离心应力和轮系振动特性进行数值分析。结果表明：叶片断口为高周疲劳断裂;优化前叶片出汽侧内弧面顶部与围带连接过渡处产生裂纹并断裂的主要原因是工作状态下叶片产生较大的扭转恢复,使围带发生严重挤压,在出汽侧内弧面顶部与围带连接过渡处产生应力集中和疲劳损伤,叶根结构设计不合理是叶片叶根发生高周疲劳开裂的主要因素,而叶片叶轮系统6节径1阶振动落入“三重点”共振区是叶片故障的次要因素;优化后叶片叶根断裂的主要原因为叶根结构设计不合理,而叶片叶轮系统11节径2阶振动落入“三重点”共振区是叶片叶根故障产生的次要因素。     

125MW汽轮机低压转子末级叶片围带断裂分析及防范

本文对嘉峪关宏晟电热有限责任公司125MW汽轮机低压转子末级叶片拱形围带断裂原因进行了分析,在分析的基础上提出了相应的防范措施,对其它行业电厂同类型或相似结构机组围带断裂的防范有一定的借鉴意义。     

俄制800MW机组高压叶片断裂分析与处理

绥中发电有限责任公司俄制800MW2号机组2次因振动异常停运,揭缸发现高压转子第2级叶片(围带)有多处断裂.从对断裂叶片材料的金相分析、断口宏观检查和电镜检验结果可知,叶片断裂位置位于叶片根部最大静应力截面,断裂性质为高周疲劳断裂;断裂的主要原因是叶片安装紧力不足,叶根之间不能紧密接触.致使叶身振动下传至叶根,导致叶片因振动疲劳产生断裂.实施了对叶片更换工艺的改进,如保证叶根之间的良好接触,增加锁叶片的安装紧力等,经机组运行实际检验改进措施是可行的.     

300MW机组低压转子次末级叶片断裂故障原因分析及处理

某电厂300MW火电机组在带满负荷运行中,汽轮机3、4号轴承振动突然增大,停机检查发现低压转子反向第4级(次次末级)有1片叶片断裂、2组围带飞脱.通过检查、试验和分析,发现叶片断裂的主要原因是该叶片材质局部不良,在现场更换该级2组共14片叶片后,机组至今运行正常.     

保定热电厂^#5机叶片断裂原因分析及处理

对保定热电厂＾＃５机压力级第１３级叶片断裂原因进行分析。采用去掉叶片围带的办法,消除了较为危险的Ｂ０型共振,改善了叶片的振动特性。     

300MW汽轮机低压转子叶片断裂原因及处理

介绍了华能德州电厂1号机组低压转子次末级叶片铆钉头断裂的情况,其原因是由于叶片振动、铆钉颈部的应力集中和围带对铆钉颈部产生较大的拉应力所造成的。制定并实施了现场修复措施,从而避免了围带脱落问题的再次出现。     

300MW机组汽轮机调节级动叶围带裂纹分析与处理

某热电公司国产300 MW燃煤汽轮发电机组在首次大修时发现汽轮机调节级动叶片铆接式围带上有1处贯穿性裂纹,通过对裂纹部位的宏观、微观、化学成分、力学性能、金相组织等进行检查和分析,认为裂纹产生的原因是围带在铆接时装配工艺不良,围带悬臂端铆接压紧力不足,在机组运行时,围带悬臂端产生振动导致围带开孔与铆钉接触部位产生磨损疲劳裂纹。给出的围带裂纹处理方案可为同类问题的处理提供借鉴。     

汽轮机叶片断裂原因分析

采用化学分析,力学性能测试及全相检验等手段,对一电站的汽轮机叶片早期断裂进行了分析。结果表明,汽轮机制适厂的叶片装配问题是造成该汽轮机末级叶片早期断裂的主要原因。     

末级叶片断裂原因分析和防范措施

通过对断裂叶片分析,认为叶片在断裂前存在隐性缺陷,从而形成了断裂的起源点缺陷,此缺陷发生在机组运行中的水蚀作用和更换司太立合金片中工艺不到位,又由于围带发生断裂后,缺陷进一步扩大,在固有的循环交变应力的长期作用下发生断裂。     

大功率汽轮机末级长叶片超声检验方法及应用

介绍了大功率汽轮机叉型叶根叶片、枞树型叶根叶片、叶身和叶根过渡区、拉筋、围带的检测方法。提出应进一步完善和开发短前沿、小晶片、低噪声的微型探头,以提高检验结果的可靠性和准确性,为末级长叶片安全运行和监督提供有效的手段。     

大功率汽轮机末级长叶片起声检验方法及应用

介绍了大功率汽轮机叉型叶根叶片、枞树型叶根叶片、叶身和叶根过渡区、拉筋、围带的检测方法.提出应进一步完善和开发短前沿、小晶片、低噪声的微型探头,以提高检验结果的可靠性和准确性,为末级长叶片安全运行和监督提供有效的手段.     

汽轮机阻尼围带长叶片振动特性研究

为了获得阻尼围带叶片的振动特性,提高汽轮机阻尼叶片的设计水平,采用扭曲梁单元模型,推导了阻尼围带的刚度和阻尼矩阵,建立了阻尼围带长叶片振动分析模型,并且在分析阻尼围带叶片整圈节径振动时采用了波传递方法进行降阶,以提高计算效率.360mm阻尼围带叶片的分析结果与实验数据吻合良好.然后再详细分析了某阻尼围带末级长叶片的振动特性,获得了叶片的扭转恢复角、静频和动频以及节径振动的坎贝尔图,其中静频和动频与三维模型计算结果对比表明了发展出来模型计算结果的合理性.文中建立的模型也可以推广应用于具有其它阻尼器叶片的动力分析,作为阻尼叶片优化设计的基础,为阻尼叶片设计提供实用工具.     

汽轮机叶片除垢工艺与腐蚀安全性分析

为保证汽轮机通流的经济性与安全性，需对动叶片进行除垢，除垢方式的选取，应在除净垢的同时，必须保障叶片不受损伤，以某电厂由例，1台100MW汽轮机大修揭缸发现高压通流腐蚀严重，尤其动叶片为甚，部分级围带有损坏现象，经过机组运行、检修、化学取样分析认为，产生此现象的基本原因由于不当的除垢方式所致。     

高水头混流式水轮机分段式下环结构转轮焊接制造技术

本文针对高水头混流式水轮机分段式下环结构转轮的特点进行了分析,其特点为:转轮尺寸小,下环为分段式结构,X型叶片长且型线复杂,叶片数量多,叶片间开档尺寸较小,流道狭长.同时,为节约成本和缩短制造周期,采用模压技术进行叶片成型技术,本文介绍了高水头水轮机叶片的模压及转轮的装焊工艺特点.     

静叶片座的加工

静叶片（导风叶）座为6个弧段拼装而成,其外径达Ф2012mm,加工后内径为Ф1804mm,壁厚较薄（最薄厚度仅为20mm）,整个部件重量达到了2．6T。静叶片装配通过橡胶压缩量进行撑紧,若装配补偿量不足,易导致导风叶松动,影响后续静叶片座的加工。同时,由于静叶片座壁厚较薄,加工易导致变形。文章通过改善静叶片装配与改变静叶片座加工装夹及吊运翻身方式来控制它的变形。     

Computational Study on the Effect of Shroud Shape on the Efficiency of the Gas Turbine Stage

The last stages of powerful power gas turbines play an important role in the development of power and efficiency of the whole unit as well as in the distribution of the flow parameters behind the last stage, which determines the efficient operation of the exhaust diffusers. Therefore, much attention is paid to improving the efficiency of the last stages of gas turbines as well as the distribution of flow parameters. Since the long blades of the last stages of multistage high-power gas turbines could fall into the resonance frequency range in the course of operation, which results in the destruction of the blades, damping wires or damping bolts are used for turning out of resonance frequencies. However, these damping elements cause additional energy losses leading to a reduction in the efficiency of the stage. To minimize these losses, dampening shrouds are used instead of wires and bolts at the periphery of the working blades. However, because of the strength problems, designers have to use, instead of the most efficient full shrouds, partial shrouds that do not provide for significantly reducing the losses in the tip clearance between the blade and the turbine housing. In this paper, a computational study is performed concerning an effect that the design of the shroud of the turbine-working blade exerted on the flow structure in the vicinity of the shroud and on the efficiency of the stage as a whole. The analysis of the flow structure has shown that a significant part of the losses under using the shrouds is associated with the formation of vortex zones in the cavities on the turbine housing before the shrouds, between the ribs of the shrouds, and in the cavities at the outlet behind the shrouds. All the investigated variants of a partial shrouding are inferior in efficiency to the stages with shrouds that completely cover the tip section of the working blade. The stage with a unshrouded working blade was most efficient at the values of the relative tip clearance less than 0.9%.     

Start-up circuit upgrading to reduce the erosion of the rotor blades of the last stages of steam turbines and prevent the mass strips of stellite plates

At turbine starts with low steam flow rates in idle mode, the low-pressure rotor blades consume energy, causing the ventilation heating of the stages and creating higher depression in them than in the condenser. This leads to the return steam flows in the exhaust of the low-pressure cylinder (LPC), reducing the heat due to the moisture of starting steam damps and cooling injections. It is shown that, as a result of upgrading with the transition to fully milled shroud platforms of rotor blades, the depression in the stages decreases and their cooling efficiency is reduced due to the removal of an elastic turn of the rotor blades under the action of centrifugal forces and seal of them by periphery. Heating the rotor blades of the last stages exceeds the temperature threshold of soldering resistance of stellite plates (150°C), and their mass strips begin. The start-up circuit providing both the temperature retention of the last stages lower the soldering resistance threshold due to overwetting the steam damps up to saturation condition and the high degree of removal from the dump steam of excessive erosive-dangerous condensed moisture was proposed, applied, and tested at the operating power unit. The investment in the development and application of the new start-up circuit are compensated in the course of a year owing to guaranteed prevention of the strips of stellite plates that lengthens the service life of the rotor blades of the last stages as well as increase of the rotor blade efficiency due to the sharp decrease of erosive wear of the profiles and reduction of their surface roughness. This reduces the annual consumption of equivalent fuel by approximately 1000 t for every 100 MW of installed capacity.     

Development of High-Powered Steam Turbines by OAO NPO Central Research and Design Institute for Boilers and Turbines

The article provides an overview of the developments by OAO NPO TsKTI aimed at improvement of components and assemblies of new-generation turbine plants for ultra-supercritical steam parameters to be installed at the power-generating facilities in service. The list of the assemblies under development includes cylinder shells, the cylinder’s flow paths and rotors, seals, bearings, and rotor cooling systems. The authors consider variants of the shafting–cylinder configurations for which advanced high-pressure and intermediate-pressure cylinders with reactive blading and low-pressure cylinders of conventional design and with counter-current steam flows are proposed and high-pressure rotors, which can increase the economic efficiency and reduce the overall turbine plant dimensions. Materials intended for the equipment components that operate at high temperatures and a steam cooling technique that allows the use of cheaper steel grades owing to the reduction in the metal’s working temperature are proposed. A new promising material for the bearing surfaces is described that enables the operation at higher unit pressures. The material was tested on a full-scale test bench at OAO NPO TsKTI and a turbine in operation. Ways of controlling the erosion of the blades in the moisture–steam turbine compartments by the steam heating of the hollow guide blades are considered. To ensure the dynamic stability of the shafting, shroud and diaphragm seals that prevent the development of the destabilizing circulatory forces of the steam flow were devised and trialed. Advanced instrumentation and software are proposed to monitor the condition of the blading and thermal stresses under transient conditions, to diagnose the vibration processes, and to archive the obtained data. Attention is paid to the normalization of the electromagnetic state of the plant in order to prevent the electrolytic erosion of the plant components. The instrumentation intended for monitoring the relevant electric parameters is described.