Study Of Numerical Simulation And Application Of Refractory Belt Arrangements On 300MW Tangential Boiler Of A Power Plant

China's coal resources are mainly distributed in North China,northwest and southwest,proven reserves in the southwest region are 141 billion tons,accounting for 9%,with abundant reserves.However,the coal quality is uneven,and most of them is classified to inferior coal;Meanwhile,China's economy had enter a phase of “New normal”,the growth of power demand slowed down,and the amount of new energy generation grow explosively.In order to promote the absorption of new energy power,the state encouraged regular coal-fired thermal power units to participate in the deep peak shaving.So the coal fired boiler,especially the boiler with inferior coal,is facing the problem of combustion stability in the low heat phase.This paper focuses on the problems of unstable combustion,low reheater steam temperature,and high carbon content of ash residue appeared in a 300 MW tangentially fired boiler with non-designed coal of a power plant in southwest China,analyzed the characteristics of the refractory belt technology in the low load;explained arrangement of some refractory belts on part water-cooled wall plays an active role in reducing the heat absorption of water-cooled wall,improving the flue gas temperature in the furnace,promoting the ignition of inferior coal,and solving the low steam temperature of the superheater or reheater during the low load period;discussed the causes of the coking and slagging of the surface of the refractory belt;proposed a plan that arrange some refractory belts on the water-cooled wall in the down burner area according to characterizes of furnace heat load.The numerical simulation of 100% load and 50% load pulverized coal combustion in this furnace is carried out by Fluent 15.0 software,and combined with the analysis of the corresponding tests,search for the optimal arrangement of refractory belt.Summarized the results of numerical simulations and relevant tests,we need to consider heat load of water-cooled wall,combustion stability,and coking characteristics in the application of the refractory belt technology.In this paper,combined with the corresponding refractory belt test,it is found that the plan 2 and 3 have moderate coking and serious coking,the safety of boiler operation is always at the first place,so when carrying out the layout of the refractory belt,all things consideration should be given to selecting the optimal arrangement of the refractory belt.The plan 1 has a certain degree of positivity for the solution to the problems existing in the current boiler operation and is more security.Arranging the refractory belt in the boiler furnace with low load,the temperature of flame is increased obviously,the stability of pulverized coal combustion is enhanced,both of the temperature of flue gas at the outlet of furnace and the temperature of reheater are improved well,indicated that the application of optimized refractory belt in inferior coal-fired boilers of low-load has a practical value for stability of pulverized coal combustion.