【作者】 马文通；

【导师】 苏明；

【作者基本信息】 上海交通大学 ， 动力机械及工程， 2009， 博士

【摘要】 21世纪火电站发展要求有较高的能源利用效率,较好的经济性并且具有良好的环保性能,即达到能源（Energy）、经济（Economy）、环境（Environment）三者结合（3E）,这一要求动摇了目前世界火电站汽轮机长期占统治地位的局面。燃气轮机及其联合循环以比投资费用低、建设周期短、供电效率高、排放污染小的明显优势,将逐步取代传统的汽轮机电站。通过建立联合循环系统的动态模型以预测其特性并优化其运行策略,已成为基础研究和工程应用两方面都很迫切的现实需要。由于压气机的特性严重依赖于转速,在燃气轮机及其联合循环各主要部件中压气机的特性计算最为困难也最为关键,压气机特性图计算的准确性对燃气轮机整机计算的可靠性具有重要影响,现代重型燃气轮机及其联合循环系统高压比、高精度的计算要求对基于部件特性的系统仿真提出严峻挑战,迫切需要改进压气机特性外推计算方法,建立适合大幅度变工况的燃气轮机及其联合循环仿真系统,并研究其运行策略已成为一个有重要意义的课题。本课题的研究网标就是寻找能够由有限的压气机高转速特性线定量计算定几何多级轴流式压气机在大幅度变工况下特性的计算方法,最终建成一套由模块化部件构成的能适应大幅度变工况特性计算的燃气轮机及其联合循环动态仿真模型;对燃气轮机及其联合循环系统的运行策略进行动态仿真研究,确定各阶段机组的运行策略。本文主要研究内容和研究成果如下:1.提出特征级方法估算压气机部分工况特性。由于压气机压比通常较大,压气机部分工况下进出口流量系数不匹配,与设计工况下的叶栅气流角差异较大,直接相似外推压气机特性时不满足相似条件,外推误差很大。通过讨论工质可压缩性对压气机效率的影响引入特征级的概念,将压气机的压缩过程分解为若干个串联的低压比特征级,可以利用相似外推方法计算完整的特征级特性图,由特征级特性图逐级计算重构出完整的压气机特性图。特征级代表对原压气机压缩过程的虚拟分解,而不考虑实际压气机各级压比分配和各级间的特性关系,物理意义在于它表征了压气机整体特性的平均级特性,只要分解级数足够多,在部分工况特性计算时可以充分逼近相似条件。采用单纯形最优化方法,以重构出压气机特性图与原压气机特性线误差最小为目标函数,由已知的有限的压气机高转速特性线确定多级轴流式压气机特征级特性。2.用SVM方法回归压气机特征级特性用支持向量机（SVM）回归算法,对由压气机多条转速特性线计算所得的不同特征级特性线进行回归分析,得到统一的特征级特性线,能够充分利用已有的数据,并且采用压气机的自身特性计算,可以充分体现压气机自身特性,进一步降低了重构后整机特性图的误差。3.外推部分工况特征级特性,并提出变几何级特性计算方法将参考转速下的特征级特性外推得到完整的特征级特性图,提出了轴流式压气机非设计工况特性换算方法,并对对相似系数的修正进行了讨论。燃气轮机部分工况特性计算问题除低速特性线的获取问题外,还面临转静叶时特性图的获取问题,利用轮周功与进出口气流角的关系,推算出特性图中转动叶片前后对应的相似点,从而解决转导叶转静叶的特性计算问题。4.建立燃气轮机动态仿真模型并对其进行部分工况运行的策略分析基于部件特性,采用模块化建模方法建立了压气机静叶可调的单轴变几何燃气轮机动态仿真系统,并进行了燃气轮机在启动、加载、减载、停机等变工况特性分析。结果表明,变几何调节后燃气和排气温度都高,排热损失的增大抵消了T₃^*增加对效率的提高。但在低负荷下,关小静叶可减少空气流量,减少机组的空载燃料耗量。启动过程中T₄^*有一峰值,在此过程中T₃^*温度也是先升后降且有一个峰值,在点火之后到脱扣之前应限制燃料供给量随转速升高的增量,控制机组启动速度,避免超温。5.建立燃气轮机联合循环仿真系统并对其进行部分工况运行策略分析建立了包括自然循环余热锅炉的燃气轮机联合循环仿真系统,并对余热锅炉的动态特性进行了分析,仿真结果指出,在燃机和汽机工况变化剧烈的条件下,汽包会出现明显的虚假水位现象,在实际运行管理中应引起重视。分析了联合循环系统在启动、加载、减载、停机等变工况下的运行策略。在负荷下降时,采取等T₄方案调节压气机可调静叶较好,它既能达到等T₃调节时的联合循环效率η_CC^N,又能在降低负荷时满足燃气温度不超温,并避免余热锅炉在超温下工作。由于启动过程中主要时间用于余热锅炉暖炉,余热锅炉的热惯性对启动速度影响最大,因此应尽可能采用热态启动的方式来减少启动时间。本文研究工作得到了国际合作项目[200310]和国家自然科学基金项目[5997022]的支持。更多还原

【Abstract】 In the 21 century,the development of power station required of high efficiency,good economics,low pollution,that’s to say,to combine the energy,economic,environment together. This requirement broke down the long time governing status of steam turbine in the world power generation,and gas turbine and its combined cycle will replace it,because of their advantage of low cost rate,short building time,high efficiency,low pollution.So it is very necessary to predict the characteristics of the combined cycle system and optimize its operating strategy by developing a simulation system.The most troublesome part in developing component based gas turbine simulation system is the performance characteristics estimation of the compressors at low rotational speed, due to the strong dependency of its performance on rotational speed and variable geometry. Thus the accuracy of compressor characteristic calculation is the critical factor in gas turbine system simulation.The high pressure and high accuracy calculation requirement of modern heavy duty gas turbine and its combined cycle system has resulted in acid challenge on modeling and simulation based on components characteristic,which request improve the compressor characteristic extrapolate computational method.Consequently,developing a wide margin varying duty gas turbine and its combined cycle simulation system then to study its operation stratagem become an significance task.The aim of this study is to research compressor characteristic extrapolate estimation method based on limited compressor high rotational speed lines to quantitative analysis compressor characteristic at wide margin varying duty,then develop a wide margin varying duty gas turbine and its combined cycle dynamic simulation system.Furthermore,study the characteristic at various work condition and to determine its corresponding operation stratagem.Main contents and conclusions of the research are described in the following:1.Introduce feature-stage method to compressor part load characteristicThe inlet and outlet flow coefficient of compressor are mismatch in part load,and the gas flow angle deviate from designed flow angle,due to the high pressure ratio of compressor. Thus,the analogy theory is not appropriate to extrapolate the characteristic map for compressors directly.Based on the discussion of the compressibility of work medium effect on compressor efficiency,the feature-stage is introduced.With the idea of dividing the compression process into infinite number of infinitesimal processes,the feature-stage characteristics are determined based on analogy theory and system identification method,and the total characteristic of compressor can be calculated stage by stage based on the characteristic of feature-stage.The feature-stage present theoretical dividing of the compressor compression process,but unnecessary to consider the pressure ratio distribution and stage characteristic relation.The physical meaning of feature-stage is it presents the average stage feature of total compressor.The similarity condition can be approach while the number of feature-stage is big enough.2.Regress compressor feature-stage characteristic based SVMBased SVM（SVM）regression method,the global feature-stage characteristic line is regressed from multiple feature-stage characteristic lines identified from different compressor rotational speed lines.Instead of statistic the characteristics of any other compressors, this method can reflect the own characteristics of the original compressor accurately.Since the stage characteristics are estimated from multi-curves of the compressor characteristic maps,this method can make a good use of available information. Furthermore,SVM method decreases the error of compressor reconstruction characteristic map.3.Extrapolate part load characteristic of feature-stage,and study variable geometry characteristic calculation methodBased on the feature-stage characteristic at referenced rotational speed,the overall performance characteristic map of compressor is reconstructed by analogy theory.Beside the part load performance characteristic estimation problem,the variable stationary vane performance characteristic estimation is a critical problem in gas turbine performance estimation.Based on the interdependence between the blade work and the blade flow angle,the relationship of the feature-stage pressure ratio and efficiency characteristic between fix and variable geometry are derivate.4.Develop gas turbine simulation model and analysis its part load operation strategy Based on component characteristic,a single shaft gas turbine simulation system with VSV compressor is developed,and analysis its performance during start up,loading, decreasing load and shutdown.Simulation test show that,the gas temperature and exhaust temperature are both increased after adjust VSVs,thus the increasing waste heat losses counteract the high T₃^* effect on efficiency.But at part load,the gas flow rate decrease after closing VSVs,which reduce idle fuel.During start up,there are a peak of T₄^* and T₃^*.So,the increment of fuel corresponding rotational speed incensement must be restricted during ignition and trip to control starting speed and to avoid over temperature.5.Develop gas turbine combined cycle simulation system and analysis its part load operation strategyA gas turbine combined cycle with natural cycle HRSG simulation system is developed and dynamical analysis.Simulation test show that,operating condition drastic variation of gas turbine and steam turbine lead to false drum water level,which should be paid attention to in exercise management,analysis of start up,loading,decreasing load and shutdown performance show that,constant T₄ adjust scheme is beneficial than constant T₃^* adjust scheme to control compressor VSVs angle while decreasing load. Which can attain high combined cycle efficiencyη_CC^N as constant T₃ adjust scheme and avoid turbine over temperature during decreasing load,then avoid HRSG over temperature. The HRSG thermal inertia is the most important influencing factor on starting speed,due to most of the startup process is spend on heating HRSG.Consequently,it should adopt warm start to decrease start period as far as possible.更多还原