蒸汽发生器堵管量对装置工作效率影响研究

核动力装置的立式自然循环蒸汽发生器工作中会由于U形管的腐蚀而需要堵管维修，其结果影响到蒸汽发生器和整个装置的工作效率。通过对一回路侧水阻力计算和二回路侧热工计算，对不同堵管量下蒸汽发生器的一回路冷却剂流量、二回路侧工作压强、蒸汽产量、蒸汽品质以及汽轮机有效功率的变化进行了详细的计算。根据计算结果对变化规律进行了分析，为蒸汽发生器的设计、维修技术的分析处理提供依据。     

U形管蒸汽发生器模型及动态仿真

针对核电站立式U形管自然循环蒸汽发生器,建立了能够描述其稳态及瞬态热工水力特性的数学物理模型,并编制了计算程序.计算和验证结果表明,该数学物理模型准确,可以与其它核电站模型一起构建核电站系统模型以进行安全分析研究或开发核电站仿真机.     

立式自然循环蒸汽发生器的热工水力特性

压水堆核电站蒸汽发生器传热面管子的腐蚀破损是核电站经常发生的事故,极大地影响核电站的可靠性和经济性。本文仅从蒸汽发生器的热工水力特性出发,提出了结构设计上的改进措施,介绍了蒸汽发生器中的沸腾传热和两相流,着重分析了某些区域内的热工水力特性。     

蒸发式换热器结构及热工水力特性计算分析

为了使设计的蒸发式换热器安全高效,讨论其计算原理和完善其设计流程意义重大。本文针对核电实验应用的蒸发式热交换器,由中国原子能科学研究院提供设计参数,采用热工水力分析和强度校核,通过制定和完善设计步骤和计算流程,最终计算得到换热器换热面积,设计裕量和一次侧阻力,同时通过作图阐明了系统特性参数如总传热系数、一次侧进出口温度,二次侧压力等随负荷的变化规律。计算结果均达到工程实际的要求,分析结果表明功率负荷的增加伴随着一次侧温度的提高和二次侧压力的降低,堵管使总传热系数减小,二次侧压力降低。研究提出了高效、安全、节能的设计方案,并为工程上蒸发式换热器设计提供了有价值的参考。     

稠油热采蒸汽发生器经济运行评价方法研究

根据蒸汽发生器现场运行工况,对蒸汽发生器经济运行评价方法进行分析研究。首先,建立相应的评价指标体系,以热效率为主要指标,排烟温度、空气系数、炉体表面与环境的温差3项为辅助指标。其次,根据现场数据的汇总分析,采用数学统计方法,对于同一功率范围内的蒸汽发生器,确定4项指标的限值。最后,采用百分法对蒸汽发生器的运行状态进行综合运行评价,进而确定出蒸汽发生器的运行状态(一级运行、二级运行、三级运行)。     

蒸汽发生器实时动态仿真

主要针对ＣＡＮＤＵ９型蒸汽发生器,建立了模块化的蒸汽发生器模型,并用图形化的仿真语言ＬａｂＶＩＥＷ编制了蒸汽发生器仿真程序,通过对ＣＡＮＤＵ ９型ＳＧ满功率运行工况的计算,表明本仿真程序的稳态计算结果与ＡＥＣＬ的实际结果比较吻合,对于引入单参数的阶跃扰动,该文对ＣＡＮＤＵ ９型ＳＧ的动态响应作了仿真计算,计算结果与实际分析完全一致,另外,单机计算的过程和结果具有实时性。     

换热表面结垢对U型管蒸汽发生器传热性能的影响分析

U型管蒸汽发生器的壳侧沉积了来自二回路系统中的腐蚀产物,结垢导致热量聚积在金属换热管上,容易造成垢下热点腐蚀,危害设备安全。为了明确结垢对蒸汽发生器传热性能的影响,本研究基于仿真平台APROS建立了U型管蒸汽发生器的分布式模型,并根据已公开论文中的数据进行了模型准确性验证;推导了污垢热阻与表面换热系数之间的关系式,分析了不同结垢厚度、位置对U型管蒸汽发生器换热区域的传热管壁面温度、流体温度、传热系数、热流密度等的影响程度。研究结果表明：随着结垢程度的加剧,蒸汽发生器的换热效率不断降低,出口蒸汽品质不断下降;结垢对沸腾段换热效率的影响比对过冷段换热效率的影响更大。     

涡流发生器表面参量与析晶污垢热阻间的关联分析

为研究换热表面上涡流发生器的流动参数和结构参量对析晶污垢的影响,并比较各类参数的关联程度。通过数值计算的方式,得出在不同入口速度、壁面温度和工质质量浓度下污垢热阻的变化情况。并得出在不同楞长、排列间距和半径下污垢热阻的变化情况。并根据灰色关联原理分析三个流动参数和三个结构参数与污垢热阻的关联程度。经分析其中两种流动参数对污垢热阻的影响高于所研究的结构参数的影响,但污垢热阻与楞长的关联度高于工质质量浓度的关联度。     

一种新式小型立式自然循环蒸汽发生器水动力特性分析

基于小型锅炉的结构特性,设计了一种新式的嵌套式小型立式自然循环燃油蒸汽发生器。针对新设计的燃油蒸汽发生器,基于传热本质采用MATLAB编程进行热力计算,进而确定合理的结构数值;接着建立蒸汽发生器的水动力学分析模型,分析了不同规格和工况下水动力学特性参数的变化趋势;最后对设计的符合热力计算误差和水动力特性参数的蒸汽发生器进行停滞和倒流验算。研究结果表明,受热最弱水管的停滞和倒流系数均符合安全设计规范。为相关的小型自然循环蒸汽发生器的设计提供了有效的计算方法。     

压水堆核电站蒸汽发生器的检查和维修

本文介绍了压水堆核电站蒸汽发生器的检查技术，缺陷预防性措施，特殊堵管准则，修理技术和比利时核电站蒸汽发生器现场维修经验。参７     

Numerical simulation of the effects of trefoil tube support plates on the flow and heat transfer characteristics of a steam generator

A three-dimensional coupled model of heat transfer tube and trefoil tube support plate (TSP) is developed based on a full-size steam generator (SG). The CFX thermal phase change model is adopted to numerically investigate the flow and heat transfer behaviors of the secondary side fluid. And the effects of trefoil TSPs and inlet subcooling on the thermal-hydraulic characteristics of tube bundle are obtained. The calculation model reasonably reveals the distributions of the flow and heat transfer parameters in the SG, especially in trefoil TSP regions. Based on the across flow velocity and density of the secondary side fluid in U-bend region, the most severe flow-induced vibration damage is predicted at the angles of 110° on the hot leg and 60° on the cold leg, respectively. Due to the effects of trefoil TSPs, vortexes are induced, the outer wall temperature in the circumferential direction shows periodic characteristic in TSP regions, which increases the possibility of aggressive solutes deposition and U-tubes rupture. In addition, inlet subcooling of the secondary side fluid has significant effects on the SG. As inlet subcooling decreases, the heat transfer is enhanced. The numerical simulation results obtained may provide guidance to facilitate the optimal design and in-depth thermal-hydraulic analysis of TSPs and SGs.     

Environmental factors causing pipe cracks and degradation in primary system components—KWU steam generator experience

The tubes in steam generators of nuclear power plants with pressurised water reactors form the link between the active primary circuit and the secondary steam water circuit. The integrity of the tubes is therefore a mandatory requirement for a safe operation. This can be met by a careful design of the steam generators as well as the whole secondary circuit by an appropriate selection of the structural materials and by a deliberate control of the water chemistry. The operating experience with KWU steam generators confirms the present and the future steam generator concept followed by KWU.     

超临界机组汽轮机调速系统模型参数确定的新方法

汽轮机调速系统模型参数的确定,对各种热力发电机组的仿真,控制系统的设计及电力系统动态研究具有重大意义.通过蒸汽发电机组有效热平衡数据计算出汽轮机模型参数,得出各种不同工况下参数的变化规律,比实测法更方便简捷实用.对600MW超临界机组汽轮机调速系统的模型参数进行分析计算,并用该模型针对特殊的阶跃响应作出仿真和分析.     

Sensitivity Analysis on Neural Network Algorithm for Primary Superheater Spray Modeling

ABSTRACT

Nonlinear, large inertia with long dead time is always associated with the main steam temperature parameter in coal fired power plant. Successful control of the main steam temperature within ±2°C of its setpoint is the ultimate target for coal-fired power plant operators. Two of the most common main steam temperature circuit are primary superheater spray and secondary superheater spray. Various methods were used to model the primary superheater spray control valve opening, and the neural network remains one of the most popular choices among researchers. It remains inconclusive which neural network algorithm types, setup, number of layers, and training algorithm will give the best result. As such, the paper shows the best setup for the neural network algorithm based on sensitivity analysis methodology for one hidden layer. The inputs selected for the neural network are generator output, main steam flow, total spray flow, and secondary superheater outlet steam temperature, while the output selected is primary spray flow control valve opening.     

多参数耦合的蒸汽动力系统运行稳定性评估方法

为解决多参数耦合情况下蒸汽动力系统整体运行稳定性评估的问题,在基于时间序列分析的单参数运行稳定性评估的基础上,提出了一种蒸汽动力系统整体运行稳定性评估方法。该方法通过分析蒸汽动力系统运行参数的相关性和作用机制,选取相关状态参数建立系统的整体运行稳定性评估指标体系;然后通过引入连接函数（Copula函数）建立稳定性指标计算模型,实现系统在多参数耦合情况下的联合失稳概率和整体运行稳定性指数计算。经实例验证,该方法能够依据监测参数历史数据,相对精确地预测出系统未来一段时间的运行状态,预测精度达到秒级。     

Nonlinear dynamic model of a solar steam generator

A thermal-hydraulic model of a once-through subcritical steam generator has been developed for predicting dynamic characteristics of solar thermal power plants as well as for control system design. The purpose of the model is to evaluate the overall system performance and component interaction with sufficient accuracy for controller design, rather than to describe the microscopic details occurring within the steam generator.The three-section (compressed water, two-phase mixture, and superheated steam) model with time-varying phase boundaries is described by a set of nonlinear differential equations derived from conservation of mass, momentum and energy. Local stability of the model has been examined at different levels of insolation. Transient response of six plant variables due to independent step disturbances in three input variables are presented as typical results.     

A Methodology to Simulate the Impact of Tube Fouling on Steam Generator Performance With a Thermal-Hydraulic Code

ABSTRACT

Corrosion product deposits in the secondary side of nuclear plant steam generators may result in tube fouling. Tube fouling is a deposit that is influential for the heat exchanges between the primary and the secondary circuits. It may cause a steam pressure decrease and a power reduction. This paper presents a methodology to simulate the impact of tube fouling on steam generator performances. Simulations are performed with ThermoHYdraulique des Composants, which is Electricité de France reference code for the three-dimensional (3D) modeling of two-phase thermal-hydraulic flows in whole nuclear components such as steam generators. Tube fouling induces an additional thermal resistance on tubes. This resistance is supposed to correspond to the conductive resistance of a dense deposit by using the Maxwell model for a continuous solid phase with inclusions. As fouling deposit thicknesses are not uniformly distributed on the tube bundle, several thermal resistance distributions are investigated. In most cases, tube fouling concentrated in the hot leg is the most influential distribution. Nevertheless, for a large amount of deposits, tube fouling uniformly distributed in both hot and cold legs becomes more influential. This simulation series is an initial step. The strategy to improve the thermal resistance model is discussed.     

AP1000核电厂二回路热力系统计算与分析

针对核电二回路系统与常规火电机组热力系统在参数设定、热力特性等诸多方面的差异,本文基于ASME PTC-6等相关标准要求,以某AP1000压水堆核电机组为研究对象,首先对该机组二回路热力系统热耗保证工况(turbine heat-acceptance,THA)下的表征算法进行研究,其次对不同设计工况下的特性参数进行计算,并在此基础上建立了核电机组二回路系统热力性能评估分析模型。随后应用该模型对案例机组在某一实际运行工况下的热力特性进行详细计算,在该运行工况下,低压缸第八级段、第九级段特征通流面积(CFA)较设计值偏差大,分别为6. 38%和17. 07%,其余级段偏差均在合理范围内,由此可初步判定第八级段、第九级段发生故障。     

塔式熔盐太阳能光热电站蒸汽发生器传热数值模拟设计计算

采用数值模拟的方式研究了50 MW塔式熔盐太阳能光热发电蒸汽发生系统蒸发器传热计算过程,利用Fluent软件建立三维模拟,通过合理的假设对蒸发器传热过程进行求解。计算结果表明:计算机数值模拟计算方法能够较好地反应蒸发器的真实传热过程,与传统理论计算、商业软件和实验数据有较好的契合度,表明数值模拟计算方法能够作为一种太阳能光热蒸汽发生器性能设计和优化的有效方法。