Large Boiler Superheater, Reheater Furnace Tube Wall Temperature Engineering Prediction

The industry of electricity is the father of national economic development,and its level is the symbol of social civilization and economic development.It is necessary to produce thermal generator unit with much bigger capacity and much higher parameter to satisfy the need of electricity increasing and the demand of economy of thermoelectricity and protection of environment in modern society. However,the accidents of overtemperature and tube explosion of superheater or reheater happened in many power plants,in our country,because of many elements in design,manufacture,operation,management and so on.They affected the power plant safe economical operationSo it is very important to study the phenomenon of overtemperature and tube explosion.The paper firstly introduced the present research situation on overtemperature and tube explosion at home and abroad,and analysed the reasons which cause the heat deviation and overtemperature and tube explosion in theory.On the base of the formers',this article made some perfects in the original calculation method of Wall-temperature,and presented general model of Wall-temperature subsection.The author deduced the calculation formulas of angle factor and radiation factor etc, which could avoid errors made by looking for curves.The author has calculated the working medium temperatures and wall-temperatures of 300MW boiler' rear platen superheater,depending upon the established model,and dealed with the results into graphics and made some analysis.Through analysing,the most dangerous parts where overtemperature and tube explosion happens are the right elbows of outmost tube of each panel,especially the eight.The first reason is high flue gas temperature and high thermal load in these places where high temperature corrosion happens. The second is the gas moves much faster caused by flue gas corridor,the tubes are scoured strongly and become much thinner,so we must take some precautions and do some monitorings in these places.In this paper,a new parameter(Φ_b=t_b-t_g) was defined to establish the relationship between the wall-temperature of the tube in the boiler and out of the boiler.Φ_b is related to flow deviation coefficient(η_G)and heat deviation coefficient(η_G).The author individually studied on the relationship betweenΦ_b and flow deviation coefficient(η_G),Φ_b and heat deviation coefficient(η_q).The particle is also analyzed the relationship of working medium temperature at outlet of tube,Φ_b,and the highest wall-temperature of the tube.The principle and quantitative method were proposed to achieve the goal using wall-temperature out of boiler to predict wall-temperature in the boiler.