Numerical Simulation Of Temperature Field Of 660MW Ultra-supercritical Boiler And Location Analysis Of Water-cooled Wall Tube Burst

In recent years,China has put into operation a large number of supercritical pressure parameter generator sets in the thermal power generation industry.Ensuring the stable operation of supercritical and ultra-supercritical boiler water-cooled wall tubes has become an important research topic that has attracted widespread attention.Among them,outages caused by water-cooled wall tube bursts accounted for more than half of the total accidents,which seriously affected the stable operation of the units.This article takes the first domestically designed and manufactured 660 MW ultra-supercritical secondary reheat boiler as an example.First,it summarizes the failure mechanism of the boiler water-wall system,and finds out a variety of factors that may cause water-cooled wall tube bursts,combined with fuzzy mathematical theory.Determine the most common cause of water wall bursting.Secondly,the model involved in the numerical simulation process is introduced theoretically.The model is constructed according to the internal structure and design parameters of the furnace.The internal structure of the boiler is divided by Gambit software.Finally,the entire combustion of pulverized coal particles in the furnace is performed using Fluent software.The process is numerically simulated.Calculate the velocity field of the pulverized coal particles in the furnace,the cloud map of the O2 content in the furnace,the CO concentration field and the most critical temperature field distribution.Through the simulation results,you can clearly see the specific combustion conditions in the furnace,so as to determine the location that is prone to cause overtemperature during the operation of the boiler.According to the characteristics of the height distribution of the heat load along the perimeter of the furnace during the combustion of pulverized coal,the water-cooled wall of the spiral coil of the 660 MW ultra-supercritical boiler furnacewas divided into 7 sections,and the equilibrium equation of each section was established.The thermal calculation was performed for different sections.Distribution of heat load on the outer wall of the effluent wall pipe.When approaching the critical working condition,the vaporization process of the working fluid in the water-cooled wall tube is calculated and determined along the height direction,the heat load distribution on the inner wall of the water-walled tube is determined,and the location where the heat transfer deterioration may occur is determined.Finally,calculate and analyze the temperature of the water-cooled wall tube burst due to the deterioration of heat transfer,and find out the specific location where the tube burst is most likely to occur.