Study On Heat-Supply Network Structure And Its Ability Of Spare-Transportation Based On Reliability

The evaluation of heat-supply network based on reliability is a crossed subject task, which involved probability theory, stochastic process theory and decision-making theory. The invalidation phan of heating system presents a perplexing evolvement process differ from the network form and its scale. It is hard to analyze and distinguish the failure pattern of components during its disabled process. With the centralized heating system becoming more mature, the foundation of synthetic reliability evaluating system and design mode of large-scale heat-supply network with high reliability are in advance application project provided with important portentous signification and economic values which cry for being solved. Thus it also possesses long-term social-economic benefits and far-ranging application foreground. By establishing a whole reliability index evaluating system, this paper promotes the optimal design method of large-scale centralized heat-supply system.Based on study of reliability related to heat-supply network in Russia, this paper establishes the reliability index system. Combining with the calculating pipe network, a reliability computing method of heat-supply network and the partition principle of equivalent zone of tree-shaped network and ring-shaped network are advanced by analyzing the logical relationship of its components. Associating with the software of valves shutoff under accident state, this paper writes a reliability index computing program—HeatNetCAD, which can be operated in Autocad environment tools by using secondary development tools--ObjectARX. The HeatNetCAD program can achieve the function of design, analysis, optimization and data update.According to the characteristic of failure occurring at heat-supply network, the diversity of different city on failure repairing level is analyzed, and the method of using failure repairing time zone for different pipe diameter as a foundation of reliability calculation of heat-supply network is presented, either. Based on the indoor air temperature drop model of being interrupted room or limited-heating supply room, the building heat-storage coefficient under different outside temperature zone are calculated by using calculating residential unit of three side of outerwall as object, and the heat-storage coefficient recommended value for several typical building configuration are brought forth. This paper also advances the reliability restricted terms of the size of satisfying reliability restriction under different outside temperature together with the allowable distance of non-spare tree-shaped heat-supply network. The reliability restriction of spare structure network and the recommended criterion of limited-heating coefficient satisfied reliability requirement in China are put forward. The relationship between limited-heating coefficient and limited-flux coefficient and the supply temperature of first network of indirect connecting system with interchanger is deducted. This function can be used to as a theoretical foundation of spare transportation design. The hydraulic results of spare structure with single connecting pipe and double connecting pipes of calculating pipe network under limited-heating supply state are analyzed. Moreover, the function of limited-flux coefficient and network configuration on three-pipe network is derived. The hydraulic analyses of calculating three-pipe network under normal state and limited-heating supply state are investigated. Comparing with another form of three-pipe network presented by scholars in Russia, the applications of three-pipe network are recommended by analyzing the calculating network and actual project. Some conclusion about reasonable setting of subsection valves and suitable loop size of ring-shaped network are presented, either.Along with the development of heat-supply network technology, especially the abroad application of large-scale ring-shaped pipe network with multi-heat source, the reliability theory of heat-supply network is attaching progressively importance to be carried out. The reliability evaluation becomes more important index on judging a system excellence like other techno-economic index. This paper aims to seek the optimal design scheme based on satisfying technique reliability of the system and form integrated reliability theory and evaluating index, in order to provide designing reference for rapidly developed centralized heat-supply project.