螺旋管式直流蒸汽发生器的集总参数动态模型

基于基本的流体质量、能量和动量守恒原理，建立了10MW高温气冷堆螺旋管式直流蒸汽发生器的动态数学模型。模型采用了集总参数的建模方法，将蒸汽发生器作为单管模型处理，分为热水段、蒸发段和过热段，且各段间具有可移动的边界。对建立的模型进行了静态和动态仿真，仿真结果表明，所建立的模型是正确和有效的，能够用来进行蒸汽发生器的动态特性仿真。     

螺旋管式直流蒸汽发生器的准稳态数学模型

为了满足模拟机实时仿真核电站一、二回路工况的需要,根据流体的质量、动量和能量守恒原理,建立了适合模拟机要求的螺旋管式直流蒸汽发生器的准稳态数学模型.该模型将蒸汽发生器作为单管模型处理,并根据水的状态将蒸汽发生器分为单相水段、两相段和过热段三大段,每大段又细分若干小段.该数学模型方程采用变步长四阶龙格库塔法联立求解一、二...     

Particle deposition and fouling in PWR steam generators

Commercial PWR steam generators have experienced reliability problems within the first decade of operation associated with material degradation, one of the causes of which is particle deposition and tube fouling. As a result steam generators often require costly outages for inspection and cleaning of fouling deposits. Knowledge of locations where sludge has accumulated in the steam generator can aid in planning and targeting locations for cleaning and removal of deposits. A particulate deposition model has been developed and implemented in the three dimensional thermal hydraulics computer code, ATHOS3 to calculate sludge and fouling regions within the steam generators during operation. This transient particle deposition model uses the thermal hydraulic field calculated by the ATHOS3 code, and the concentration of magnetite particles entering the steam generator to calculate the particle distributions and deposition on vertical and horizontal surfaces within the steam generator. Results of some simulations of operating steam generator designs are presented in this paper. These results show that preferred regions for deposition include hot side upper bundle and a kidney shaped region on top of the tube sheet.     

蒸汽发生器优化设计后的运行特性研究

以秦山核电厂相关设备为原型,基于已开发的蒸汽发生器模型及优化计算程序,利用系统分析程序RELAP5验证该模型的准确性,并对优化设计所给出的蒸汽发生器的设计方案的稳态运行特性和负荷提升瞬态运行特性进行了模拟分析。结果显示：已开发的蒸汽发生器数学模型是合理的;在超负荷运行过程中,经优化设计的蒸汽发生器存在循环倍率过低问题;RELAP5可作为核动力设备优化设计方案的验证程序。     

Dynamic model for control system design and simulation of a low temperature nuclear reactor

A lumped parameter dynamic model for the primary-loop and the U-tube steam generator of a low temperature power reactor is developed based on the fundamental conservation laws of fluid mass, energy and momentum. The dynamic model is formulated by coupling the point kinetics with reactivity feedback and the thermal-hydraulics of the reactor. The developed dynamic model is implemented on a personal computer using MATLAB/SIMULINK. Numerical simulation results for steady-state and transient responses are then presented, which show that the steady-state precision of the newly developed dynamic model is acceptable and the trend of the transient responses is correct. In addition, the “swell and shrink” behavior of the U-tube steam generator is also verified by numerical simulation. This newly established model can be utilized to control system design and simulation for the low temperature power reactor.     

套管式直流蒸汽发生器动态实时仿真研究

基于基本的流体质量、能量和动量守恒原理,建立了套管式直流蒸汽发生器的动态数学模型。该模型采用集总参数和移动边界的建模方法,将直流蒸汽发生器流道分为欠热段、沸腾段和过热段。采用Gear算法求解,对建立的模型进行稳态和动态仿真,并利用RELAP程序进行校验。结果表明：所建立的模型是正确和有效的,能用来进行直流蒸汽发生器的动态特性实时仿真。     

集成神经网络方法在蒸汽发生器故障诊断中的应用

针对蒸汽发生器传统故障检测与诊断方法的不足,提出了基于集成神经网络的蒸汽发生器故障检测与诊断的新方法。该方法采用两个神经网络。一个神经网络作为蒸汽发生器的动力学模型,用于蒸汽发生器的重要运行参数的预测,其原理是通过检测蒸汽发生器运行参数监测信号值与相应的蒸汽发生器神经网络模型预测值之间的偏差来确定是否发生了异常,如果某一参数偏差超过了预先给定的极限,就认为发生了异常。另一个神经网络作为故障分类模型,用以对蒸汽发生器故障进行分类,给出故障的类型。由两个神经网络监测和诊断结果的融合给出蒸汽发生器故障较为清晰的信息。仿真结果表明,该方法能够提高蒸汽发生器监测与诊断的能力。     

蒸汽发生器二次侧汽液两相流数值模拟

以大亚湾核电站蒸汽发生器为原型,在相似原理的指导下,建立了蒸汽发生器“单元管”三维物理模型,采用Particle模型和热力学相变模型,并基于CFX软件实现了蒸汽发生器二回路侧两相流流动与沸腾换热特性数值模拟。计算结果表明：满负荷运行时,沿传热管高度升高,蒸汽发生器的传热系数及截面含汽率均呈上升趋势,其平均传热系数的数值模拟结果与Rohsenow经验关联式计算结果间的误差为8.4%,出口质量含汽率与大亚湾核电站实际运行参数相符。热相变模型在蒸汽发生器两相流数值模拟中的成功应用,可为蒸汽发生器热工水力的准确分析提供参考。     

带螺旋缠绕管的双面加热管套管直流蒸汽发生器稳态换热研究

介绍了一种新型的内管为螺旋管的管套管式双面加热直流蒸汽发生器.为编写稳态换热分析程序建立了一种固定二次侧焓值边界计算模型.该模型依据二次侧流体相的变化,将蒸汽发生器划分为三个分区:单相液区、两相区和单相汽区.程序的计算结果与文献中实验结果吻合较好,并从计算结果分析得出了该蒸汽发生器的一些结构参数对换热效果的影响规律.     

直流蒸汽发生器控制系统研究

在所建立的直流蒸汽发生器动态数学模型基础上,研究和分析了直流蒸汽发生器在各种扰动下尤其在负荷变化下的响应,得到了在这些扰动下直流蒸汽发生器压力和各段长度的变化规律。在此基础上研究了串级控制系统和基于神经网络的自学习模糊控制系统,并进行了控制系统仿真研究,结果显示两种控制系统都具有较好的控制能力。研究结果对实际直流蒸汽发生器的控制系统设计具有一定的指导意义。     

Steady thermal hydraulic characteristics of nuclear steam generators based on the drift flux code model

To investigate the steady thermal hydraulic characteristics of U-tube steam generator(SG), a 1D simulation code based on the four-equation drift flux model is developed. The U-tube channels presumably consist mainly of the primary channel, secondary channel, and tube wall. In the sub-cooling regions of the primary and secondary channels, flow is simulated using the single-phase flow model, whereas that in the boiling regions of the secondary channels is simulated using the four-equation drift flux model. The first-order equations of upwind difference are derived based on the staggered grid. Steady-state thermal hydraulic parameters are obtained with a cross-iteration scheme of heat balance and natural circulation requirement. The developed code is applied to analyze the SG behavior of the Qinshan I Nuclear Power Plant under 100%, 75%, 50%, 30%, and 15% power conditions. Analysis results are then compared with the simulation results obtained using RELAP5.     

蒸汽发生器强迫循环流动不稳定性分析

介绍了蒸汽发生器强迫循环下稳态和瞬态的计算方法.从基本的守恒方程出发,充分考虑了蒸汽发生器的结构和可能的流动状态以及换热形式,建立了一套完整的数学计算模型.程序采用Gear算法,通过理论计算得到了流动不稳定性脉动曲线和相应的不稳定区域.本文还研究了压力、质量流速、进口过冷度和进、出口节流对不稳定性的影响.     

直流蒸汽发生器全范围流动与传热数值模拟

以BW公司实际运行的直流蒸汽发生器为原型,采用两流体三流场数学模型数值模拟直流蒸汽发生器二次侧单相液对流换热区、核态沸腾区、蒸干后区域、过热区(即全范围)的流动沸腾换热现象。结果表明:本文采用的模型可较好地预测直流蒸汽发生器全范围的流动与传热特性,数值模拟结果与运行数据符合较好;蒸干后质量含汽率低于热平衡质量含汽率,结合壁温变化趋势表明直流蒸汽发生器运行过程中蒸干后区域存在一定程度的热力非平衡;随着流动换热的发展,表面传热系数迅速上升,蒸干的发生导致传热性能急剧下降,在蒸干后区域及过热蒸汽区表面传热系数缓慢上升。     

HTR-PM直流蒸汽发生器的建模与分析

球床模块式高温气冷堆核电站示范工程（HTR-PM）采用两座模块式高温气冷堆带一台汽轮发电机组的技术方案,为了开展其运行特性研究,清华大学核能与新能源技术研究院开发了针对HTR-PM的工程模拟机,其中螺旋管式直流蒸汽发生器的模型还需进一步完善。本文深入分析了螺旋管式直流蒸汽发生器的流动、换热规律,明确了蒸汽发生器一次侧和二次侧的流动与换热模型,通过对稳态工况中分布数据的详细分析,说明了模拟结果的正确性。为适应更多模块的高温气冷堆核电站的运行分析要求,通过网格划分方案的讨论与优化,在保证实时性的前提下,提高了蒸汽发生器中流动与换热模拟的准确性,为下一步采用工程模拟机开展其运行特性研究打下基础。     

运行条件对蒸汽发生器热工参数影响的仿真研究

以减轻蒸汽发生器破管事故及考察核电站电力升级为目的,参考大亚湾核电站蒸汽发生器的运行参数,基于分布参数法建立了核动力蒸汽发生器一维数学模型,开发了基于MATLAB的动态仿真程序,进行了改变运行条件时蒸汽发生器热工参数仿真计算。计算结果表明:与满负荷正常运行条件相比,在降低二回路运行温度或增加二回路流量时,二回路预热段变短,出口焓大幅升高;质量含汽率在降低温度时提高54%,增加流量时提高28%;一、二回路及管壁整体温度降低;一回路和内壁温降增大。该计算结果揭示了蒸汽发生器的内在传热规律,可为缓解U形管恶化及提升电力的相关操作提供一定理论依据。     

A theoretical model for the calculation of large transients in nuclear natural-circulation U-tube steam generators (Digital code UTSG)

A newly developed nonlinear transient model for the calculation of the dynamic behaviour of a vertical natural-circulation U-tube steam generator together with its steam removal system is presented. The steam generator is considered to consist of a heat exchange section, a top plenum, a downcomer region and a steam removal system with a sequence of relief and/or safety valves, isolation, bypass, turbine-trip and turbine-control valves and a steam turbine. Possible perturbations from outside can be: inlet water temperature, inlet water mass flow and system pressure on the primary side, feed water temperature, feed water mass flow and outlet steam mass flow disturbed by actions of the different valves within the steam removal system on the secondary side. Based on this theoretical model the digital code UTSG has been established. Post-calculations of start-up tests at a PWR nuclear power plant simulating perturbations both on the primary and secondary side of the steam generator and similar calculations for the corresponding ATWS-cases will show the efficiency of the code UTSG and the underlying theoretical model.     

核电站蒸汽发生器数字化仪表与控制对象实时仿真系统技术研究

采用U型管蒸汽发生器动态特性分析数学模型,研制开发了核电站蒸汽发生器实时仿真系统。该系统与控制系统形成能够相互作用的闭环系统,用于为核电站数字化仪表与控制(I&C)开发提供仿真对象及进一步控制方案研究。运用该系统对蒸汽发生器变工况进行了计算,所得结果与核电站仿真机的计算结果符合较好,为核电站仪表与控制(I&C)系统数字化开发提供了理论依据。     

Analysis of Reverse Flow in Inverted U-Tubes of Steam Generator under Natural Circulation Condition

In this paper, we report on the analysis of reverse flow in inverted U-tubes of a steam generator under natural circulation condition. The mechanism of reverse flow in inverted U-tubes of the steam generator with natural circulation is graphically analyzed by using the full-range characteristic curve of parallel U-tubes. The mathematical model and numerical calculation method for analyzing the reverse flow in inverted U-tubes of the steam generator with natural circulation have been developed. The reverse flow in an inverted U-tube steam generator of a simulated pressurized water reactor with natural circulation is analyzed. Through the calculation, the mass flow rates of normal and reverse flows in individual U-tubes are obtained. The predicted sharp drop of the fluid temperature in the inlet plenum of the steam generator due to reverse flow agrees very well with the experimental data. This indicates that the developed mathematical model and solution method can be used to correctly predict the reverse flow in the inverted U-tubes of the steam generator with natural circulation. The obtained results also show that in the analysis of natural circulation flow in the primary circuit, the reverse flow in the inverted U-tubes of the steam generator must be taken into account.     

套管式双面加热蒸汽发生器的热工水力分析

为研究套管式双面加热蒸汽发生器在稳态和瞬态过程中的热工水力特性，建立了描述蒸汽发生器物理现象的一维均匀流数学模型。应用该模型，开发了可计算稳态和瞬态工况下一回路和二回路冷却剂温度场、焓场的直流蒸汽发生器热工水力程序。计算结果对直流蒸汽发生器结构设计、运行具有指导意义。      

核动力装置蒸汽发生器数值模拟计算

建立了一个合理完善的核动力装置蒸汽发生器动态特性分析数学模型，并运用Ｇｅａｒ方法对此模型求解。研制了用于核动力装置蒸汽发生器稳定运行及扰动和事故工况下动态数值模拟的安全分析程序。运用此程序对秦山核电厂蒸汽发生器失去给水的事故进行了计算，所得结果与大型程序ＲＥＬＡＰ－５计算结果符合较好，并对蒸汽发生器几种不同扰动序列的计算结果进行了理论分析。