Research And Application Of General-purpose Software For Boiler Hydrodynamic Calculation Based On The Theory Of Pipe Network Calculation

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.