【作者】 谢金芳；

【导师】 童水光； 钟崴；

【作者基本信息】 浙江大学 ， 化工过程机械， 2011， 博士

【摘要】 长期以来,锅炉水动力计算主要采用经典的图解法。该方法在求解存在多回路嵌套关联复杂结构锅炉水动力系统的水动力特性时往往难以直接求解,而不得不进行简化处理,致使计算精度难以保证。本文突破性的提出了一种“基于管网计算理论的通用锅炉水动力计算方法”,该方法将锅炉水动力系统理解为“空间立体型受热管网系统”,通过抽象“节点”和“阻力区段”,建立了以“有向流程图”描述的锅炉水动力计算模型。基于研究提出的计算模型和算法,开发了“通用锅炉水动力计算系统”。论文的主要内容如下：◆基于对锅炉水动力系统与管网计算理论中有向管网图结构相似性的分析,创新性的提出了将任意结构形式的锅炉水动力系统看作是由若干个阻力部件相互衔接构成的“空间立体型受热管网系统”。通过抽象“节点”和“阻力区段”,创建了由“有向流程图”描述的锅炉水动力计算模型。其中,锅筒、集箱、分汇以及逻辑划分点等被抽象为“节点”,而两个相连节点间的连接通路被抽象为“阻力区段”。在阻力区段上可能包含有表现为沿程摩擦阻力的直管路,以及表现为局部阻力的弯头、截面突变、节流圈等。此外,提出将计算模型中节点与区段间的连接点抽象为“流体节点”,以描述水动力系统中流动工质的属性。◆依据管网计算理论与锅炉水动力计算基本原则,提出了一种适用于求解由有向流程图描述的任意结构形式锅炉水动力系统水动力特性的通用算法。该算法以节点流量连续性方程与回路的能量平衡方程为约束条件,在考虑锅炉水动力系统存在受热、相变、以及重位压差作用等特殊性情况下,以有向流程图中各基本回路为研究对象,分“粗略校正流量”和“精细校正流量”两个阶段,并提出分别采用不同的流量调节策略进行管网平差计算,获得满足工程精度要求的计算结果。由此求解锅炉的水动力特性。与图解法相比,该算法具有优良的通用性,且可显著提高锅炉水动力计算的精度和效率。◆以研究提出的水动力计算模型及其通用算法为基础,研发了一套“通用锅炉水动力计算系统”。该系统采用面向对象技术,按照与有向流程图模型自然映射来定义类的原则,建立了通用锅炉水动力计算系统的统一软件描述模型。该模型通过定义抽象类屏蔽了部件类型的多样性,而在逻辑关系维护和算法实现上均采用抽象类的统一接口来组织,保证了系统具有优良的通用性和可扩充性。同时,采用了图形化模型输入技术,在可视化窗口中动态搭建系统模型,提高了软件系统的易用性。目前,通用锅炉水动力计算系统已在国内多家A级锅炉设计制造企业中得到应用,并为相关企业研究解决了锅炉水动力性能设计中的若干关键技术问题,实现了各种复杂结构锅炉产品水动力性能的设计计算。实践表明,该系统不但可以提供准确、可靠的锅炉水动力特性计算结果,而且具有通用性、易用性和可扩展性的显著特点,能够大大提高锅炉企业产品水动力性能设计计算的速度和效率。更多还原

【Abstract】 The boiler hydrodynamic calculation had been mainly adopting graphic method for a long time. The graphic method was difficult to directly solve the hydrodynamic characteristics of a complex boiler hydraulic system which containing multiple associated loops and had to simplify the calculation. So it could not guarantee the accuracy of the results. The thesis proposed "a general hydrodynamic computational method of boilers based on the theory of pipe network calculation". In the method, the boiler hydraulic system was interpreted as "a three- dimensional heated pipeline system". Through abstracting "the nodes" and "the resistance sections", a boiler hydrodynamic computing model was created. Based on the proposed computing model and the proposed algorithm, the thesis developed "a general hydrodynamic computing system of boilers".The main research contents on this subject were explained as follows:Based on the structural similarity analysis of the boiler hydraulic system and the directed graph in the pipe network, the thesis revolutionarily proposed that a boiler hydraulic system of arbitrary structure could be interpreted as "a three- dimensional heated pipeline system" which composed of a number of interrelated resistance components. By abstracting "the nodes" and "the resistance sections" to the pipeline system, a general computational model of boiler hydrodynamic calculation was created which described by a directed graph. The drum, headers, tees, logical division points, etc. were abstracted as "the nodes". And the connecting pipes between two nodes were abstracted as "the resistance sections". In any section, it might include the straight pipe which was expressed as the frictional resistance, and might also include the bends, variable cross-sections, throttle valves, etc. which were expressed as the local resistance. In addition, the connecting point between a node and a section was abstracted as "the fluid node" for describing the fluid properties in boiler hydraulic system.According to "the theory of pipe network calculation" and "the basic principles of boiler hydrodynamic calculation", the thesis presented a general algorithm for solving the hydrodynamic characteristics of arbitrary structure boiler based on the proposed computational model which described by a directed graph. Under the constraint conditions of the flow continuity equations of nodes and the energy balance equations of loops, simultaneously considering the influence of heat and gravity, the solving procedure of the algorithm was divided into two stages with the basic loops in the directed graph as studying objects which specifically including "rough flow regulation" and "refined flow regulation". Different adjustment strategy was implemented in each stage to gradually reduce the resistance closures of basic loops until the solution accorded with engineering accuracy requirement, then solving the boiler hydrodynamic characteristics. Compared with the graphic method, the proposed algorithm has excellent generality and is easy to be programmed; moreover, both the accuracy and the speed of calculation are greatly improved.+With the support of the created computational model and the proposed algorithm, a general hydrodynamic computing system of boilers was studied and developed. By adopting the object-oriented technology, it created the universal software model for representing all kinds of boiler computational models described by directed graphs. In the software model, the diversity of boiler component types could be wrapped by defining the abstract classes, and the maintenance of logical relationships and the realization of main algorithm can be achieved via the object identifiers of abstract class type and the uniformed abstract interfaces. And all of these would improve the adaptability and extendibility of the model significantly. Meantime, the directed graph computational model was build by using graphical modeling tools, which would improve the usability of the software system.At present, the general hydrodynamic computing system devoloped in the thesis has been applied in many A-level boiler manufacturing enterprises. A number of key technology problems from the hydrodynamic calculation was studied and solved by using the computing system. In addition, the computing system completed the hydrodynamic characteristics calculation on various complex boilers. All of these indicate that the general hydrodynamic computing system is not only able to provide accurate and reliable results of boiler hydrodynamic calculation, but also having the features with venerability, usability and extensibility. Moreover, the computing accuracy and efficiency of the boiler hydrodynamic performance is greatly improved in boiler enterprises.更多还原