600MW汽轮机不同负荷下高压缸法兰螺栓密封应力分析

以600MW汽轮机高压缸为例进行不同负荷下高压缸法兰螺栓密封应力分析，给出了高压内缸和外缸压差随机组功率变化曲线，进一步给出了法兰螺栓所需密封应力随机组功率变化曲线，为延长机组连续运行时间、增长大修周期时间和法兰螺栓剩余寿命在线监测提供理论依据。     

核电汽轮机高压缸法兰结合面接触分析

大型核电汽轮机高压缸尺寸大、结构复杂,运行中多种因素可能导致其受力不均,进而影响汽缸法兰结合面接触状态。以某大型核电汽轮机高压缸为研究对象,建立其三维模型,并用ANSYS/WORKBENCH计算分析了稳态运行时汽缸轴封处温度分布与螺栓预紧力对法兰结合面接触状态的影响。计算结果表明,在给定条件下,螺栓的预紧扭矩为6800N·m、高压缸轴封处沿轴向的温度梯度不高于30℃/m时,法兰结合面接触状态良好;螺栓的预紧扭矩为9200N·m、高压缸轴封处沿轴向的温度梯度不高于40℃/m时,法兰结合面接触状态良好;螺栓的预紧扭矩为12 000N·m、高压缸轴封处沿轴向的温度梯度不高于50℃/m时,法兰结合面接触状态良好。     

核电汽轮机差胀分析

1 前言 310MW核电汽轮机系利用美国西屋公司引进600MW火电汽轮机为基础设计而成,去除了原高压缸,其积木块为051—074—074。修改设计600MW中压缸(051)为核电高压缸,而低压缸基本与火电通用,回转设备移至二低压缸之间。推力轴承位于高压缸前轴承座内,高压缸两端用定中心工字梁与轴承座相连,机组死点位于1号低压缸中间。机组运行时,1号低压缸调阀端推动高压缸与前轴承座向调阀端膨胀,而1号低压缸电机端及2号低压缸向电机端膨胀。我们采用西屋方法对核电汽轮机进行轴向差胀分析。径向差胀主要发生在低压缸末几级,因结构相同,工况参数相近,可直接采用火电机组值,不再作径向差胀分析。     

某中间再热机组低压缸胀差偏大原因的分析及处理

徐州诧城电力有限公司的135MW机组存在低压缸胀差偏大的现象,机组的低压缸胀差已经大到影响机组安全运行的程度,为彻底弄清楚低压缸胀差偏大的原因并予以解决,对今后的机组安全运行起到保障作用,本文以徐州诧城电力有限公司的4号机组为例进行分析,并提出有效的处理方案,使差胀问题得到解决.     

M701F4改进型燃气_蒸汽联合循环中低压合缸机组 冷态快速启动优化

为解决M701F4改进型燃气-蒸汽联合循环中低压合缸机组冷态启动时间长约12 h的问题,通过分 析该类型机组在启动前的冷态倒暖、启机过程、机组振动、高压缸膨胀及高压缸胀差等情况,并利用机组检修 机会,清理轴封及高压缸内脱落变形残留物,同时采用一些创新方案,从邻机高参数疏水管路接引蒸汽作为 冷态倒暖汽源,提高倒暖参数,结合近中压缸启动方式,汽轮机冲转升速至全速后尽快并网,有利于高压缸多 进蒸汽带负荷暖缸,开机过程用预测高压缸胀差控制带负荷暖缸速度等办法,将机组冷态开机时间缩短至3 h 左右,极大缩短同类型燃气轮机联合循环发电机组冷态启动时间,对中低压合缸机组的优化设计或技术改造 有借鉴意义。     

冷态起动升负荷阶段法兰加热对法兰温度场和膨胀量的影响

本文介绍了东汽二十万千瓦汽轮机高压缸法兰在起动带低负荷过程中的温度场计算工作和计算结果,对有法兰加热与无法兰情况下的温度分布和汽缸法兰的膨胀量作了分     

优化开停机操作的探讨

分析了电厂汽轮机开停机过程中可能出现的各种热物理现象，以及这些现象可能对机组运行的安全和经济性带来的影响，并介绍了作者在实践过程中摸索到的有关经验和应对措施，指出开机时正确掌握抽真空时机和冷却水泵和高低加热器的启动时机，同时合理使用法兰螺栓加热装置和其他装置，可以降低启动能耗，减少故障发生。     

大型汽轮机组的高压缸旁路系统

大型机组在汽轮机启动、电网事故、甩负荷等过程中,会出现高压缸排汽止逆阀关闭、高压缸内呈鼓风状态的情况。为了有效防止高压缸超温,在高压缸排汽口处设置高压缸排放装置,综合考虑多方面的因素,着重讨论了高压缸排放装置的选择和入口参数的确定,保证合理地设置高压缸排放装置,以减少汽机寿命损耗,使整个机组安全性得到提高。     

350 MW机组汽封间隙调整及通流改造方案

在华能大连电厂3号机组A级检修过程中,发现高压外缸上抬量很大,且在未紧螺栓的情况下高压外缸间隙严重超标。通过计算半缸与全实缸洼窝中心的差值、测量各级隔板的椭圆度、改变螺栓热紧角度等措施,调整了轴系中心和汽封间隙。从启机过程和最后效率实验结果来看,这种方法是可行的。研究成果可为类似机组检修提供借鉴。     

核电高压汽缸中分面的密封试验

从核电汽轮机高压缸对中分面密封的特殊要求出发，介绍了汽缸中分面法兰螺栓的应力计算和测试，通过对比分析，提出了解决中分面密封的设计方法。     

输电钢管塔新型锻造法兰受弯性能研究

针对输电钢管塔采用传统锻造法兰和新型锻造法兰两种节点连接形式,在ANSYS软件中选取螺栓孔中心到法兰盘外缘和颈根的距离、螺栓个数为参数,建立输电钢管塔的法兰连接有限元模型,研究了两种锻造法兰节点在拉弯作用下的受力及破坏模式。结果表明,传统锻造法兰有螺栓弯曲屈服、法兰颈屈服两种破坏形式;新型锻造法兰有螺栓弯曲屈服、钢管拉伸屈服两种破坏形式。     

输电钢管塔新型锻造法兰破坏模式研究

针对输电钢管塔采用传统锻造法兰和新型内外双层锻造法兰两种节点连接形式,选取法兰盘厚度、螺栓个数、螺栓孔中心到法兰外缘的距离及螺栓孔中心到法兰颈根的距离4个计算参数，利用Ansys软件建立了输电钢管塔法兰节点连接有限元模型，研究了在轴向拉力作用下两种锻造法兰节点的破坏模式。结果表明，传统锻造法兰有螺栓弯曲屈服、法兰颈变坡段与直坡段接触点屈服两种破坏形式；新型内外双层锻造法兰有法兰颈根屈服、钢管拉伸屈服两种破坏形式，同时法兰盘厚度、螺栓个数均小于传统锻造法兰。     

On analysis and redesign of bolted L‐flanged connections

In wind turbine towers, the preferred design is circular tubes that are connected by a bolted flange joint. The design is typically that of an L‐flange resulting in an eccentrically loaded bolted connection. The eccentricity results in a non‐linear relationship between external load on the tower and the tensile force in the bolt. In the literature and also in standards, different models are presented for this important non‐linear response. In the present paper, a simplified expression for the non‐linear force response is presented based on finite element calculations using contact analysis. The L‐flange connection is in essence a bad design because it leads to a non‐optimal ratio between external force and bolt force. Furthermore, bolt bending results in an even higher bolt stress resulting in a reduction of strength. The present paper presents simple modifications of the L‐flange design that considerably improves the connection strength. Copyright © 2017 John Wiley & Sons, Ltd.     

Creep analysis of bolted flange joints

In the petrochemical and nuclear industries, the difficulty in assessing the effect of creep on the tightening load of bolted flanged connections is recognized. Under high temperatures, the leak tightness of bolted joints is compromised due to the loss of the bolt load as a result of creep of not only the gasket and bolt materials but also the flange material. Apart from acknowledgment of this effect, there exists no established design calculation procedure that accounts for creep. This is because the relaxation of the bolt load and the corresponding loss of the gasket contact stress are not easy to assess analytically. The main objective of the work is the development of a simple analytical solution to the creep-relaxation problem encountered in bolted flange connections of the float type. Particular emphasis is put towards relaxation caused by the flange and bolt material creep.     

风力发电机组塔架螺栓连接公差问题研究

针对风力发电机组塔架法兰的螺栓连接,基于IEC 61400对其公差的要求和可能发生的平面度问题,采用有限元方法进行应力计算.结合实际风力发电机组法兰螺栓连接实例计算,对塔架法兰内倾量和平面度公差对筒壁和螺栓的影响进行总结,提出法兰内倾角公差设计方法,比较平面度公差对螺栓的影响,可为提高塔架法兰连接的可靠性提供更为严谨的...     

The modelling of bolted flange joints used with disc springs and tube spacers to reduce relaxation

Bolted flange joints are prone to leakage when exposed to high temperature. In several cases, the root cause is relaxation that takes place as a result of material creep of the gasket, the bolt and the flange. One way to overcome this problem is to make the joint less stiff by introducing disc springs or the use of longer bolts with spacers. Although widely used, these two methods have no reliable analytical model that could be used to evaluate the exact number of washers or length of the bolts required to reduce relaxation to a minimum acceptable level.This paper describes an analytical model based on the flexibility and deflection interactions of the joint different elements including the axial stiffness of the flange and bolts, used to evaluate relaxation. The developed analytical flange model can accommodate either disc springs or longer bolts with spacer tubes to reduce the bolt load loss to a maximum acceptable value. This model is validated by comparison with the more accurate FEA findings. Calculation examples on a bolted flanged joint are presented to illustrate the suggested analytical calculation procedure.     

钢管塔内外锻造法兰及内外刚性法兰的承载力和变形性能对比分析

针对锻造法兰刚度不足的问题,提出了一种新型的锻造法兰连接形式——内外锻造法兰,基于ANSYS软件建立了内外锻造法兰的有限元模型,同时根据榕江大跨越输电塔中的内外刚性法兰的缩尺模型,建立了内外刚性法兰的有限元模型,对两种内外法兰进行了加载计算,比较了二者的位移—承载力变化。根据内外锻造法兰的受力变形特征,重新选取了内外锻造法兰的螺栓规格,并再次对比分析了内外锻造法兰与内外刚性法兰的位移—承载力性能,获得了内外锻造法兰的优点。     

The structural behaviour of a bolted,flanged connection subjected to a cyclic load

This paper presents the results of an elastic—plastic bi-dimensional finite element analysis for a bolted flange in a boiling water reactor vessel.The calculations were performed by the finite element program ADINA using the incremental-iteration technique. The aim was to follow the stress and the strain of a bolted flange subjected to a cyclic load, consisting of four steps: the bolt load; the pressure load with decreasing of bolt load; depressurisation with increasing bolt load; and, at the end, unbolting.The calculations were performed progressively varying the height of the flange so that the maximum stress intensity was $\text{3S}{}_{\mathrm{<mtext>m</mtext>}}$.The number of cycles was sufficient to verify the conditions of shakedown or ratcheting.Numerical analysis can clarify our knowledge in this field, where the ASME III Code NB-3228 rules are obtained from an analytical computation for simple structure, using over-simplified assumptions on material constitutive equations, such as perfect plasticity.     

吸收式热泵耦合大型抽凝机组供热的经济性分析

针对供热需求与供热能力之间的矛盾和电站低品位冷凝热利用不充分的问题,以300MW抽凝供热机组为实例制定了吸收式热泵耦合抽凝机组供热方案。结合耦合供热方案提出供热面积扩容率的概念,通过对耦合供热与传统热电联产供热两种供热方式的定流量热力计算,以供热面积扩容率、能源综合利用率和热电总收益三个经济性指标为比较标准,进行了经济性指标对比分析。结果表明:耦合供热方式在机组不增容的前提下能够扩大供热面积,提高能源利用率,并增加热电厂的经济收益。