【作者】 杨志平；

【导师】 杨勇平；

【作者基本信息】 华北电力大学 ， 热能工程， 2013， 博士

【摘要】 能源是社会发展的物质基础,是国家的经济命脉,长期以来,中国火力发电消耗煤炭占煤炭消费总量的50%左右,300MW及以上大型火电机组在我国发电能源结构中占有举足轻重的低位,对我国电力行业乃至整个工业领域的节能降耗具有重要意义。火电机组的实际能耗受环境与资源条件、运行工况及外部负荷变化等因素的影响,能耗水平具有鲜明的时变特征；针对上述特点,本文以大型燃煤发电机组汽轮机热力系统为研究对象,考虑复杂多变外部因素和负荷条件影响,综合应用热力学第一、第二定律和汽轮机组变工况理论,从全工况角度研究机组能耗在整个汽轮机热力系统中的分布特性；从过程、单元及系统等不同层面,研究设备间、系统间的性能耦合机制；研究机组能耗对主要决策变量的动态响应规律；开展综合考虑外部复杂条件的大型燃煤发电机组能耗状态的节能诊断研究,进一步完善大型燃煤发电机组的节能诊断方法,以指导大型燃煤机组的深层次节能降耗,论文研究成果具有重要的应用价值。采用详实的数据对我国火力发电机组的能耗状况进行深入研究,并进行国内外对比分析,摸清了目前我国火力发电机组的能耗水平,指出火电机组构成差异是导致我国火电机组整体效率水平偏低的主要原因；并以2010年的数据为基础,预测2015年和2020年我国火力发电的能耗水平,为我国火力发电装备的节能对策研究和节能政策的制定奠定基础。考虑燃煤发电机组的环境条件和负荷条件,综合应用热力学第一、第二定律,将汽轮机变工况与凝汽器变工况相结合,研究大型燃煤发电机组汽轮机热力系统的全工况能耗分布特性,得到大型燃煤发电机组在不同环境温度、不同负荷工况下汽轮机热力系统的能耗时空分布规律。提出以低压缸末级组压力比与末级组效率的变化关系确定汽轮机排汽焓的方法,为全工况条件下整个汽轮机热力系统基准态的能耗分布准确评价提供可靠的分析方法,在此基础上研究大型燃煤发电机组汽轮机热力系统主要决策变量的能耗敏度特性,以1000MW超超临界燃煤发电湿冷机组与直接空冷机组为研究对象,得到不同决策变量在不同负荷时的能耗敏度规律,为在役机组准确进行节能潜力诊断提供保障。将基于热力学第二定律的单耗分析引入大型燃煤机组的节能诊断,针对在役燃煤发电机组,通过相同边界条件下基准态能耗分布与实际运行状态能耗分布的对比,揭示机组能量损失的部位和相应的节能潜力,并给出对应的具体节能措施与对策,进一步完善了大型燃煤发电机组的节能诊断理论与方法。更多还原

【Abstract】 Energy, the civilization basis of society development, is undoubtedly one lifeline of China’s economy. Coal consumption for power generation has long been more or less half of its total consumption amount. Additionally, large-scale coal-fired power generation units with a capacity of300MW or above have already played a decisive role in the overall energy structure. Thus, further improving these systems can contribute significantly to the reduction of fuel consumption of power generation or even the whole industry area.In general, fuel consumption rate of a real coal-fired power generation unit depends highly on many factors, such as environment-and-resource situation, operation condition and external load change, which make it vary largely with time. Corresponding to these features and on the basis of the first and second laws of thermodynamics and the off-design prediction of steam turbine performance, detailed distribution characteristic from the perspective of all operating conditions, the coupling mechanism of thermodynamic performances among components and system at the process, component and system levels, dynamic response principles of fuel consumption rate with main decision variables were comprehensively and thoroughly investigated. Energy-saving diagnosis of unit states considering complicated external factors was also studied in a penetrating manner and further improved to guide deep reduction of their fuel consumption. From these viewpoints, this research is expected to be of significant practical value.According to the deep and detailed data investigation of the fuel consumption conditions of existing coal-fired power plants in China and comparisons with the situation in developed countries, current fuel consumption levels of different units were clarified. It is, thus, pointed out that the contribution differences of various coal-fired power plants are the key reasons, leading to the high-level fuel consumption rate of the whole coal power generation industry. In this context, the overall fuel consumption levels in2015and2020are reasonably predicted based on the data of2010, which is necessary for the development of energy-saving policy and solution of thermal power plants.Considering the environment and load conditions, off-design performance predictions of turbine and condenser were effectively combined to reveal the spatial distribution of fuel consumption in one specified unit for all load conditions, from the1st and2nd laws of thermodynamics. Thus, the spatial-temporal distribution principle of fuel consumption within turbine thermal system at different environmental temperatures and loads is concluded. New calculation method of turbine exhausted steam in accordance with the relationship between pressure ratio and efficiency of the final stage group was proposed, which provided a reliable analysis approach to accurately evaluate the energy consumption distribution of one unit at its reference state. Then, the sensitivities of fuel consumptions of1000MW ultra-supercritical coal-fired power plants with wet and dry cooling systems on main decision variables were obtained separately at different load factors. These form solid basis for the accurate energy-saving diagnosis of existing units.The specific fuel consumption analysis, a variant of2nd law of thermodynamics, was successfully introduced to the energy-saving diagnosis of power plants. Focusing on the existing power generation units, the comparisons of fuel consumption distribution between reference state and the real operating state at the same boundary conditions can reveal the sites and magnitudes of additional fuel consumption rates and corresponding energy-saving potential, provide certain specific energy-saving measure and solution, and further improve the method and approach for the energy-saving diagnosis of large-scale coal-fired power generation units.更多还原