Analysis And Research On Heat Deviation Of High Temperature Heating Surface In Power Station Boiler

With the rapid development of social economy, demand for electricity is increasing. To meet the power supply, thermal power generating units is also growing toward high-capacity, high-parameter and environment-friendly direction. However, over temperature tube rupture often occurs in large utility boiler high temperature heating surface. In pressure parts of a boiler, superheater is the highest operating temperature heating surface. High temperature and pressure steam flowing in the tube, heat transfer performance poor, and the tube in high-temperature gas, in the harsh environment, therefore, the proportion of accident damage is very large. Large power station boilers have high steam parameters, once over-temperature tube rupture occurs, not only a lot of the working fluid and fuel will be lost, reducing the economy of units, but also it will affect the safety of the unit, and even impact the stability of the grid. For these reasons, it has important practical significance to research the causes of heat deviation of high temperature heating surface in power station boiler and the methods of wall temperature calculation.For this problem, in this paper, firstly boiler heating surface heat deviation theory was introduced and analyzed from the steam side flow deviation, flue gas side endothermic heat deviation and the same screen heat deviation. Then take a large power plant600MW supercritical boiler as the research object, through numerical simulation software FLUENT, select the maximum load conditions, the entire combustion chamber numerical simulations was carried out to obtain the distribution of the furnace flue gas temperature and velocity, and in this base, calculate the wall temperature of platen superheater. Summarizing the original wall temperature calculation method, a suitable wall temperature calculation model was established, the platen superheater tube is divided into several small units, heat transfer and the wall temperature was calculated individually for each pipe section, comparing the calculation results, drawing the wall temperature distribution, finding the highest wall temperature point and analyzing the danger point. It has important reference value for the choice of low NOx combustion transform and the prevention of over temperature tube rupture. In addition, it is guidance for optimize design of superheater system and accident analysis.