The Three-Dimensional Calculation About The Pipe Surface Temperature Of The Boil's Super-heater And Re-heater

In recent years, the failures of super-heater and re-heater occur frequently in the large-capacity boiler, which result in shutdown of the unit. To some extent, excessive temperature exist in super-heater and re-heater of many large units, which prevents the units from working safely and economically. The exact calculation and monitoring to the tube temperature of super-heater and re-heater are very important. Because the structure of boiler is very complex and it operates in the different conditions, the real temperature of super-heater and re-heater is very difficult to get. It is necessary to find a new way to solvethis problem.The three-dimensional calculation introduced in this paper is a new method. It cancalculate the super-heater and re-heater's tube temperature when the boiler works under the varying operating conditions, and the calculation will be more particular and the result will be more various. This method is different from the old ones, which calculate the average tube temperature and consider the difference caused by the tube's position. Firstly, the tubes are divided into many small segments, then the thermal equilibrium principle applied to each segment and the tube temperature calculated, lastly, the three-dimensional distribution of temperature of heat walls is calculated. This new method predicts the distribution of the super-heater and re-heater's tube temperature more precisely, and the concept of the calculation is more concise.We calculate the anterior-screen super-heater, hider-screen super-heater, high temperature super-heater and high temperature re-heater of 330MW boiler in ZhongNing power plant. In order to enable the calculation to have the practical significance, we calculate separately the tube temperature when the boiler burn the design coal, and when the boiler work under 7 kind of operating conditions, and an appreciation on these is made.