【作者】 王芃；

【导师】 邹平华；

【作者基本信息】 哈尔滨工业大学 ， 供热、供燃气、通风及空调工程， 2010， 博士

【摘要】 供热系统作为社会的“生命线工程”,关系着人们的生产和生活,同时也是国民经济的重要组成部分。具备高温、大容量的集中供热系统一旦发生故障,将可能破坏生活区和公共建筑的供热,恶化人们的生活和工作环境,并导致无法估量的社会性后果。为保证供热系统的可靠运行,俄罗斯学者在结构备用、输送能力备用、维修时间、限额供热量等多方面对供热系统的设计提出了严格的要求,并规定了系统的功能质量可靠度指标,具备了一整套可靠性设计和最终评定的方法。然而,在供热系统的设计过程中,尚缺乏各阶段的可靠性评价方法,如针对管网拓扑结构的设计,管段容量的设计等。另外,由于区域经济、技术发展的差异,我国各地区供热系统的设计和运行管理水平参差不齐。针对我国目前供热系统设计与运行中存在的问题,本文主要研究热网设计时管网拓扑结构和管段容量设计阶段,系统的可靠性评价方法,以及适合评价现存的各种设计与运行水平不同的供热系统的可靠度指标。针对供热系统设计各阶段中系统的可靠性评价问题,首先基于网络系统的连通性理论,分别从热用户、热源和系统的角度建立供热系统的连通问题。基于最小路集矩阵建立连通可靠度的表达式,同时改进了网络最小路集的搜索算法,提出求解逻辑和的矩阵分割算法;另外,建立管段连通重要度以反映管网中各管段对系统可靠性的影响,形成较完整的基于连通可靠度的系统结构备用评价方法。通过算例分析了管网结构、热源位置与数量等因素对连通可靠度的影响。其次,基于最大流——最小割原理将供热平面管网转化为边权传输网,提出了考虑故障工况限额供热的管段容量设计方法,并建立最大流可靠度、限额供热流可靠度与非满负荷流可靠度评价系统的输送能力备用。结合系统综合可靠性的评价,通过某单热源供热系统的改扩建分析,指出结构备用和输送能力备用的提高均能有效改善供热系统的综合可靠性;同时也说明在供热系统的设计阶段,根据连通可靠度和流可靠度分别指导管网拓扑结构和管段容量的可靠性设计是有效的手段。供热系统的综合可靠性评价,应遵循故障隔离、故障管网重构、故障工况仿真及可靠度计算的步骤。首先通过构造包含阀门信息的混合关联矩阵,提出矩阵扫描法完成供热平面管网到阀门网络模型的转化。基于阀门网络模型的关联矩阵,给出故障元件对应的关阀方案和关断区域的计算原理,通过搜索故障隔离时平面管网的所有连通子图,重构故障平面管网和空间管网。此外,基于阀门网络模型分析管网中的特殊阀门:无效阀门和并联阀门集合,给出它们的判定准则及相关性质。假设完全可控和不可控作为系统可控程度的上下界估计,基于热网水力计算的基本模型和故障空间管网,针对完全可控与不可控系统在故障工况的调节特性分别建立仿真模型。通过算例分析,探讨了不可控与完全可控供热系统故障管网水力工况的特点,指出完全可控的供热系统是实现热网可靠性设计的手段,是与系统结构备用和输送能力备用相匹配的控制措施。最后根据状态空间法和功能质量的可靠度评价指标,分析设计热负荷可靠度指标的不足,建立限额供热可靠度指标综合评价系统的可靠性。于是,通过阀门网络、故障工况仿真模型和限额供热可靠度指标的计算完成供热系统的综合可靠性评价。基于限额供热可靠度,分析循环水泵、可控性及多管制敷设方式等对供热系统可靠性的影响。给出采用多管制敷设时热源出口干线的最小长度要求,指出陡峭型的循环水泵性能曲线可以提高系统可靠度。提出基于一类问题的极限限额供热可靠度,以说明供热系统在管网拓扑结构、热负荷分布、管径以及阀门设置不变的条件下,系统可达到的最大限额供热可靠度。并基于极限限额供热可靠度,分析了多热源多环供热系统中阀门增设的优化方案。更多还原

【Abstract】 District heating system, as society’s“Lifeline Engineering”, has great relationship with people’s work and life, and also is an important part of the national economy. It can lead to bad heating of living quarters and public buildings, and people’s daily life and working environment are deteriorated when the heating system with high temperature and high capacity breaks down. Thence, it must cause incalculable social consequences. In order to make sure reliable operation of heating system, Russian scholars raised strict requirements on design of heating system, like the spare structure, the spare transmission capacity, repair time and quota heating. They also put forward reliability index of function and quality, and then proposed a set of reliability design and final assessment methods. However, the lack of reliability evaluation methods during design of heating system still exists, such as design of network topology and pipe capacity. In addition, design and operation management of heating system in different districts has great difference because of the difference of regional economic and technological development. In view of present problems of heating system design and operation in China, this paper mainly researches on reliability evaluation methods of heating system when design network topology and pipe capacity, and reliability index which is used to evaluate existent heating system with different design and operation level.For the problem of reliability evaluation in each step of heating system design, firstly, according to heat users, heat source and system, connectedness model of heating system is built based on connectedness theory of network system. The connectedness reliability is expressed by min-path matrix. The improved traversal algorithm of min-path set and the matrix partitioning algorithm for solving Boolean sum have been put forward. In addition, the connectedness importance degree of pipe is built to reflect the influence of each pipe on reliability of heating system. Thus, a fairly method to evaluate the spare structure based on connectedness reliability is formed. The effect of network topology, location and the number of heat source on connectedness is analyzed by practical examples.Secondly, the planar heating network is transformed into edge weighted communication net based on the maximum flow and min-cut theory. The reliability design method of pipe capacity is raised considering quota heating under failure condition. Then, reliability indices for evaluating the spare transmission capacity of heating system are established, including maximal flow reliability, quota heating flow reliability and part-load flow reliability.Combined with the integrated reliability evaluation of heating system, the increase of structure and transport capacity spare can effectively improve the integrated reliability of heating system through analysis of reconstruction of a district heating system with single heat source. It can illustrate that reliability design of network topology and pipe capacity based on connectedness reliability and flow reliability is an effective method in design process of heating system.Integrated reliability evaluation of district heating system should follow the steps of failure isolation, reconstruction of failure network, and hydraulic simulation of failure network and reliability calculation. First, planar network is transformed into the valve net based on matrix traversal algorithm by constructing a hybrid correlation matrix which contains information of valves. Scheme of shutting valves and shutting area when component fails can be calculated by correlation matrix of the valve net. Reconstruction of failure planar network and spatial network is finished by searching all connected sub-graph of planar pipe network when failure component is isolated. In addition, the invalid valve and parallel valves in network are analyzed based on the model of valve net, and their determinant rules and related characteristics are given.Assuming completely controllable and uncontrollable performance as the upper and lower bounds of controllable degree of heating system, based on the primary hydraulic model and failure spatial network, the simulation models of completely controllable and uncontrollable system are established according to their regulating characteristics under failure conditions. Hydraulic characteristics of the uncontrollable and completely controllable heating system are analyzed by a practical example. The completely controllable system is the means to realize reliability design, which is an applicable control measures for structure spare and transport capacity spare.Finally, according to the state space method and the reliability evaluation index of functional and quality, and considering the disadvantages of the designed heat load reliability, in this paper the quota heating reliability is established to evaluate heating system synthetically. The integrated reliability evaluation of heating system is finished by calculation of valve net, hydraulic model of failure network and quota heating reliability.The effects of circulating pumps, controllability, and multi-pipe installation on the reliability of heating systems are analyzed based on quota heating reliability. This paper presents the minimal length requirement of main line from heat source when multi-pipe installation is used, and indicates that circulating pumps with steep performance curve can improve system reliability. The ultimate quota heating reliability based on the first kind of problem is presented, which illustrates that system reliability can achieve maximum when network topology, heat load distribution, diameter and valve settings stay in the same conditions. Optimal scheme of additional valve setting in a heating system with multi-source and multi-loop is analyzed based on the ultimate quota heating reliability.更多还原