Design Of Steam-water System For A Thermal Power Plant Unit And Stress Analysis Of Main Steam Pipeline

The rational use of energy and improvement of energy efficiency affects not only the economic development of society but also the ecological environment,countries all over the world have paid deeply attention to it in recent years.An important measure to realize the above purpose is to construct thermal power plants for cogeneration and centralized heating.As an important component of a power plant’s operation system,it makes the design work of steam-water system to be an extremely important part in this project.the main steam pipeline is one of “four pipelines”,its design is also crucial,and pipeline stress analysis is a key part of the pipeline design task.Based on the cogeneration project under construction in Quzhou Jiangshan,this paper studied theoretically and practically on the partial subsystems and main steam pipeline stress of the power plant’s steam-water system.On the basis of familiarity with the design theory and specification of power plants,combined with the engineering design and calculation,the main work and achievements are as follows:The existing heat load and recent added heat load were organized and counted,by converting enthalpy value,the design heat load was obtained,on this basis,the three main engines(type、capacity、working temperature and pressure,etc)of the power plant were selected,then combined with documents of boiler and steam turbine factories,the principle thermodynamic system diagram was drawn up,the steam-water balance and technical economic indicators of average design heat load was calculated.The main steam and heating steam system in this thermal power plant’s steam system were studied and designed.The main steam system’s type of single common header was chosen reasonably,and the main steam system was designed,Based on the actual situation of this project,the layout of the main steam pipeline was designed in details;some related auxiliaryequipments of heating steam system were selected and heating steam system was designed,then use Auto CAD to complete the design of main steam system’s process system diagram and piping layout diagram 、heating steam system’s process system diagram.Stress analysis of main steam pipeline.use professional pipeline stress analysis software CAESAR II to calculate the detailed stress of the main steam pipeline which is with high temperature and pressure,according to results checked the primary stress and secondary stress and analyzed the displacement so as to verify the rationality of the pipeline design.At the same time,the calculated thrust results can not only prevent the damage to the equipment,but also provide the design basis for the building structure specialty.The feed water and drainage water system in this thermal power plant’s steam system were studied and designed.Based on the engineering practice and the design calculation,some related auxiliary equipments of water system were selected and feed water、drainage water system were designed,then use Auto CAD to complete the design of feed water and drainage water ’s process system diagrams.Through the design of this paper,the design heat load 50.11t/h of the power plant was obtained,on this basis,the 75t/h circulating fluidized bed boiler and steam turbine B7.5MW were chosen,the relative design of steam-water system were completed and pipeline stress was analyzed,all these work may had certain practical engineering value for the design of similar small cogeneration project.