【作者】 贾瑞宣；

【导师】 徐鸿；

【作者基本信息】 华北电力大学（北京） ， 热能工程， 2011， 博士

【摘要】 热力发电厂冷端本质上是一个多设备、多过程的复杂系统,探寻其能耗表征及控制规律一直是电厂节能的关键,也是深度挖掘节能潜力,实现节能降耗的难点之所在,因此,研究其中的科学问题,提出既紧密结合实际、又有一定理论性和通用性的解决方案,对于进一步提高冷端系统经济性有重要意义。论文实现节能降耗的关键点：冷端最大能耗设备的优化设计、优化选型和系统的优化调度。而难点在于从现有的理论中进一步凝炼能耗的本质,为能耗降低提供理论上的解决方案。三部分既相互独立又相互支撑、相互印证。主要科学问题涉及：1.根据叶轮机械内流理论,对叶轮流道内二次流、旋涡、回流损失机理进行分析,指出传统理论的不足之处主要表现在两个方面：第一是其对象主要针对轴流式；第二是过于重视表象分析,疏于探索力学本质。在此基础上,从旋涡动力学角度寻找规律,指出和二次流损失相关的一些定性关系。2.找到影响二次流形成的关键性影响参数,将其作为自由参数进行优化,从而提出了一种基于二次流控制的叶型优化设计新方法。实例分析证明,该方法可以有效地削弱或消除二次流的影响,提高效率。3.从混流泵效率曲线特点及变化规律,分析了其对变速调节的适应能力；从混流泵的负载特性以及负载率对双速电机效率的影响规律,分析循环水泵采用双速电机调节的合理性、科学性。4.针对冷端凝汽器真空对机组性能的影响,以及循环水泵台数调节的特点,提出了最小匹配供水量的概念,以此为调节的导向。在研究有效控制循环水泵实际供水量对最小匹配供水量偏离程度的过程中,提出了多速交叉并联理论,以此为指导制定优化改造方案。5.综合考虑循环水泵不同改造方案对循环水流量、汽轮机微增功率、循环水泵电耗的影响,将基于设备优化改造的最优真空作为优化目标值,并确立了循环水系统的优化目标函数。最后以某电厂冷端优化改造为例,验证了多速交叉并联理论的科学性和有效性。更多还原

【Abstract】 Cool-ends of the power plants are essentially complicated systems with many equipment and many processes. To decrease their energy consumption and to obtain the optimal control stratege is always concerned by thermal power plant energy-saving pursuer. At the same time, it is also pivotal and difficult part for deeply sinking energy-saving potential so as to realize the aim. Hence, to study on pivotal question and to put forward resoluble project has great significance for more improving the cool-end system economic. The project has theory connotation and currency characteristic with a certain extent. Three pivotal parts for energy-saving is proposed in the paper i.e. optimum design of the most energy consumption equipments in the cool-end system, optimization selecting type, system optimizing regulation. It is difficult to abstract energy consumption hypostasis from existing theory so as to provide theory support for solving energy consumption pivotal parts. Three part is independent, suspensory and probative one another. The main contributions of the paper are as follows:1. According to turbomachinery flow theory, loss mechanism has been analyzed for the secondary flow, vortex, return inside the impeller. Pointed out the inadequacy of traditional theory is mainly manifested in two aspects. The first is its object mainly for axial. The second is too much emphasis on appearance analysis, neglect to explore the mechanical nature. On this basis, from the point of vortex dynamics theory, some qualitative relations associated with the secondary flow losses is obtained.2. The critical impact parameter to affect the formation of secondary flow has been found. If it is as free parameters to optimize, an optimal design new method based on secondary flow control for blade can be obtained. As demonstrated by examples, this method can effectively reduce or eliminate the impact of secondary flow and improve efficiency.3. Its ability to adapt to the speed regulation has been analyzed from the efficiency curve characteristics and changing law for mixed flow pump.At the same time, rational and scientific features can be found for circulating pump with two-speed motor adjustment from mixed flow pump load characteristics and the load rate on the two-speed motor efficiency law.4. For the cold side of condenser vacuum on the unit performance, and the features by adjusting the number of circulating water pump, the new concept of minimal matching water quantity has been put forward. It can serve as a guide for optimal regulation. During the research of control the deviation level by circulating water pump actual water quantity to minimal matching water quantity, multiple-speed chiasma and parallel connection theory has been proposed. The optimization alteration project was developed by it.5. Considering the impact by various reform programs to circulating pump circulating water flow, a slight increase of turbine power, power consumption of circulating pump, alteration will be based on the best vacuum equipment optimization as the optimization target, and objective function has been established to a circulating water system. Finally, as a cold end optimization of transformation shown, verifying the theory of multi-speed cross-parallel scientific and effective.更多还原