Problems and prospects of using structural materials for horizontal steam generators

Prospects for using new structural materials instead of Grade 08Kh18N10T steel for making heat-transfer tubes for horizontal steam generators with the purpose to increase their service life from 30–40 to 60 or more years are considered.     

Thermal-hydraulic tests of a recirculation cooling installation for the Rostov nuclear power station

Results obtained from thermal-hydraulic tests of the recirculation cooling installation used as part of the air cooling system under the containments of the Rostov nuclear power station Units 3 and 4 are presented. The operating modes of the installation during normal operation (air cooling on the surface of finned tubes), under the conditions of anticipated operational occurrences (air cooling and steam condensation from a steam-air mixture), and during an accident (condensation of pure steam) are considered. Agreement is obtained between the results of tests and calculations carried out according to the recommendations given in the relevant regulatory documents. A procedure of carrying out thermal calculation for the case of steam condensation from a steam-air mixture on the surface of fins is proposed. The possibility of efficient use of the recirculation cooling installation in the system for reducing emergency pressure under the containment of a nuclear power station is demonstrated.     

Studying the damageability and short-term mechanical properties of grade 10Kh9V2MFBR-Sh steel during its combined thermal and mechanical loading

Results from a research work on studying the changes in the structure and properties of Grade 10Kh9V2MFBR-Sh high-chromium steel used as material for tubes occurring in the course of its long-term ageing under the effect of thermal and mechanical factors are presented. The objective of the work was to select a possible procedure and criteria for estimating the reliability of the metal of steam line tubes during their long-term operation.     

空冷凝汽器单排扁管的研制

阐述了电站空冷系统中凝汽器冷却管的发展历史。介绍了单排管凝汽器的特点。具体介绍了对单排管束的扁管、翅片及焊接的研制过程。。     

间接空冷散热器及空冷钢塔流动和传热数值研究

依托实际工程项目,利用计算传热学(NHT)软件FLUENT,对自然通风状态下,某2×350 MW机组外覆铝板钢结构空冷塔及四周表面式间接空冷散热器的流动和换热性能进行了数值模拟、分析和研究。确定了考核工况基准下,不同环境风速对空冷钢塔通风量和间接空冷散热器散热量的影响。模拟结果显示,随着环境风速的增加,空冷钢塔通风量和间接空冷散热器散热量减小。     

钢制椭圆管矩形翅片空冷传热元件热力及阻力性能试验研究

通过对钢制椭圆管矩形翅片的不同管径、不同翅片间距的空冷传热元件进行热力及阻力性能试验,给出了相应的传热关联方程式及阻力方程式,可供工程设计时参考。     

超超临界锅炉水冷壁开裂原因分析

通对某超超临界锅炉在安装期间发现裂纹的水冷壁鳍片和管子进行化学成分、机械性能、示波冲击、显微硬度、金相组织、断口形貌试验等分析,得出鳍片部位存在折叠和微裂纹等轧制原始缺陷。诱发鳍片与管子焊接过程中产生裂纹并扩展的主要原因是鳍片硬度高、脆性大,而且存在原始缺陷;次因之一是鳍片与管子的焊接质量差、氧气切割时产生热应力,在切开的尖锐的直角缺口部位产生较大的应力集中,导致鳍片在缺口处开裂并扩展;次因之二是水冷壁管屏在生产工地到安装工地的吊装及运输过程中在二次应力的作用下产生多次振动和冲击,在裂纹的启裂部位产生弯矩和扭矩,导致裂纹迅速开裂并扩展。     

Experience gained with carrying out restorative thermal treatment of stamped-and-welded elbows made of grade 15Kh1M1F steel after long-term operation

We present the results obtained from experimental investigations of samples based on which the schedule of restorative thermal treatment of large-diameter stamped-and-welded elbows made of Grade 15Kh1M1F steel were selected, as well as data obtained in the course of restorative thermal treatment of a full-scale stamped-and-welded elbow carried out in accordance with the selected schedule.     

不锈钢管替代凝汽器铜管的可行性分析

针对近年来火力发电厂频繁出现凝汽器铜管泄漏引起水质恶化的问题,探讨了用不锈钢管替代铜管的可行性。为此,首先,结合广州发电厂有限公司的实际情况分析了凝汽器铜管穿漏的原因;其次,分析了凝汽器内冷却水管束布置的缺点,认为应将其改为交叉排列,并用此方式对凝汽器的凝结量进行了计算,计算结果证明用不锈钢管替代铜管是可行的;最后,对替代后的效果及运行中需注意的问题进行了说明。     

Failure rates of tube systems used in delivery-water heaters of T-250/300-240 turbine units

Field experience data on the stress corrosion cracking of a tube system made of Grade 12Kh18N10T austenitic stainless steel are given. The pattern of damages and the factors causing them to appear in certain locations are analyzed. Design and operational solutions aimed at making the heaters more reliable are proposed.     

直接空冷机组凝汽器管束表面温差产生原因分析与处理

某电厂直接空冷机组凝汽器冬季运行时有多列冷却三角两侧管束的温差达20℃,常发生管束冻裂事故。分别从设计、安装、运行等方面分析了凝汽器管束表面产生温差的原因。经过多次现场运行调整操作和现场试验,确定温差的形成原因为安装工艺不当,因单侧抽真空管道坡度不合理造成其通流能力不足。通过调整管道安装坡度,最终解决了直接空冷机组凝汽器管束表面温差问题。     

我国首台超临界机组X20CrMoV121钢受热面管状态分析

为全面了解火电厂X20CrMoV121钢受热面管长期运行后的安全状况,对某电厂X20CrMoV121钢末级过热器管及高温再热器管进行了力学性能测试、显微组织分析及高温持久强度试验。试验结果表明,运行管与原始管相比强度有所下降;沉淀相发生熟化,同时还出现了局部板条特征减弱,板条内出现亚结构,位错密度明显降低,且在亚结构内位错呈定向排列的趋势;高温持久强度仍然高于设计值。综合分析认为,经12万h运行后的X20CrMoV121钢管产生了一定程度的老化,但仍可满足设计工况下安全运行的要求。     

Investigating the service characteristics of grade 10Kh9V2MFBR-Sh steel

We present the results obtained from chemical and carbide analyses and a study on determining short-term mechanical properties and critical brittleness temperature, as well as data on the heat strength and heat resistance properties of new Grade 10Kh9V2MFBR-Sh steel, which is an analog of Grade Kh10CrWMoVNb9-2 (P92) steel.     

Development of radial-flow type internally oil-cooled oil-filledcable

A radial-flow type, internally oil-cooled, oil filled, paper-insulated cable has been developed. The oil flows radially through the paper insulation, decreasing the thermal resistance of the insulation. The decreased thermal resistance as well as the cooling effect of the oil flow in the central oil duct and the outer oil duct under an aluminum sheath increase the current capacity. A method for calculating the cooling characteristics is introduced. The results of initial electrical tests and a long-term field test, confirming the stability of the cable and accessories, are presented     

国产空冷单排管流动和传热性能研究

波状翅片扁平管,即单排管是直接空冷凝汽器的一种基本换热元件。单排管外空气侧的流动和传热性能研究,对于直接空冷凝汽器的优化设计和安全运行具有重要的意义。在不同迎面风速下,对国产空冷单排管空气侧进行三维数值模拟,并对速度场、温度场进行分析和研究,拟合出单排管阻力和传热系数随迎面风速变化的计算公式,为直接空冷系统的优化设计提供帮助。     

高压真空断路器用散热器的自然对流换热特性

为提高高压真空断路器的运行安全,以一种新型高压真空断路器为背景,采用计算流体动力学方法研究了不同环境温度下,圆柱形散热器竖直肋片间自然对流换热特性。结果表明:采用扩大计算区域和设置压力边界条件的方法来模拟计算自然对流换热是恰当的。在散热器肋片缝隙的进口处,气体温度较低、流速较小;在肋片缝隙中部,气体温度升高、流速较大;越靠近肋片根部,气体温度越高,但由于粘性阻力大,所以在肋片根部速度较小。在相同的环境温度下,随着肋片温度的逐渐升高,肋片的换热能力也逐渐升高;在相同的肋温情况下,随着环境温度的逐渐升高,肋片的换热能力逐渐下降。所得的肋片缝隙内自然对流的流动换热特性、肋片表面的平均Nu数对高压真空断路器散热器肋片的热力设计和进一步优化设计有重要的意义。     

超超临界锅炉水冷壁管传热恶化对横向裂纹影响的有限元分析

为研究不同传热条件下水冷壁管的温度及热应力分布特征,以某1 000 MW超超临界锅炉水冷壁管为对象,建立了水冷壁管的三维有限元模型,分正常传热和传热恶化2种情况进行了计算。计算结果显示,向火侧壁面热负荷、管内传热系数对传热恶化后的温度和热应力有显著影响,在尚未达到屈服前,水冷壁管的热应力与温度基本呈线性关系。传热正常时,水冷壁管鳍片处温度和热应力值大于水冷壁管向火侧顶点相应值,而向火侧顶点发生破坏的可能性较小;在传热恶化时,水冷壁管向火侧顶点的温度和热应力迅速增大,并明显高于水冷壁管鳍片处,传热恶化的反复出现引起的交变应力最终导致水冷壁管横向裂纹的产生。     

交错蛇形短翅片对扁平管外传热的强化

在火电机组直接空冷凝汽器中采用空冷技术,可以有效降低富煤缺水地区火力发电对水资源的消耗。通过数值模拟的方法,对锯齿形短翅片应用于火电机组直接空冷凝汽器扁平管空气侧强化传热的可行性进行探讨。研究发现,,采用所提出的扁平管交错蛇形短翅片结构,与传统的连续蛇形翅片相比,在各种迎面风速条件下均能起到强化空气侧传热的效果。随着短翅片交错排数的增加,翅片变短,强化传热的效果更为明显。在n 5时,强化传热综合性能评价准则数(performance evaluation criteria,PEC)可达到1.05~1.09;但随着迎面风速的增加,流动阻力的增加变得更为显著,强化传热的效果受到抑制。利用实际数据对模型的有效性进行验证,并对计算域网格数进行校验,结果表明所得结论具有一定的可靠性。     

三排管直接空冷凝汽器冻结原因

针对山西漳山发电有限责任公司300MW机组发生三排管直接空冷凝汽器冻结问题,分析了三排管直接空冷凝汽器管束冻结的原因,内因是在迎风侧第1排翅片管内蒸汽倒流并有空气聚积,外因是环境温度低。文章阐述了三排管直接空冷凝汽器在设计中所存在的不足及其改进建议,供已投运的三排管直接空冷凝汽器改造和拟建机组设计参考。     

Steam Condensation from a Moving Steam-Gas Mixture

To date, heat exchange has been studied to the greatest extent for the case of the condensation of pure still and moving steam as well as for the case of condensation from a still steam-gas mixture. There are hardly any papers available wherein a moving steam-gas mixture with a substantial content of noncondensable gases is considered. To investigate this process, an experimental workbench of the working section has been developed, which makes it possible to determine the local values of the heat transfer coefficient from the steam-gas mixture to the walls of cooled heat-exchange tubes at different parameters and velocities of the gas-steam mixture. In the first four rows of tubes of the working section, there is no cooling, and their function consists in a hydraulic stabilization of the flow. In the fifth and the sixth row of tubes, the wall temperature of the cooled heat-exchange tubes is measured for determining the heat transfer coefficients from the moving steam to the tube walls. The seventh row of tubes is also not under cooling. Measuring tubes with temperature sensors have been manufactured that make it possible to obtain the wall temperature for determining the heat transfer coefficient. The adopted scheme of steam motion and the measurement system make it possible to obtain correct results of the heat and mass transfer investigation in the course of steam condensation from a gas-steam mixture with a significant content of noncondensing gases. The studies on steam condensation from a moving steam-gas mixture have been carried out in the range of parameter ρw² = 9.5 ? 66 Pa and at a volume concentration of air in the steam amounting up to ν_air = 0.18. Convective heat transfer coefficient α values for the heat transfer from a moving steam-gas mixture to the wall of a cooling tube were obtained. At small values of parameter ρw² = 9.5 Pa and the volume fraction of the air content ν_air = 0.06 in the steam, the average heat transfer coefficient exhibits a decrease by a factor of two as compared with that inherent in the condensation of almost pure steam. At the values of parameter ρw² = 66 Pa and at ν_air = 0.06, the average heat transfer coefficient decreases by 1.3 times. The studies on almost pure steam are in good agreement with Berman’s dependence.