Effect Of Furance Structure On The Performance Of Large-sized Reciprocating Grate Boiler

In recent years, layer combustion boiler’s design and manufacturing capabilities in China increase rapidly, the power boiler is in the increasing. Large-sized reciprocating grate boiler’s efficiency has improved significantly, it has obvious economic and environmental benefits. But at present the theoretical research for boiler is still stay in the phase about the small boiler and the chain boiler,the detailed theoretical research of large-sized reciprocating boiler is less. Because the large-sized reciprocating grate boiler emerged a short time, its theories and experience are not rich enough, so the actual operation of the large-sized reciprocating grate boiler has many problems, there are a lot of room for its improvement. Furnace space as the main place of flue gas combustion and heat transfer, it had significant effect on the structure for reciprocating grate boiler performance. Therefore, improve the reciprocating boiler to save energy, protect the environment, is of great significance to reduce greenhouse gas emissions.The SHW98-1.6/150/90- H reciprocating grate boiler is the research’s prototype. The paper use Fluent software for numerical simulation of the flue gas flow and heat transfer, study the influence of boiler structure for large reciprocating boiler performance, in order to make the boiler has higher thermal efficiency, longer life and lower economic cost. The paper’s physical model and mathematical model parameter conditions are in accordance with the date through the actual investigation of the actual operation, so the numerical simulation has authenticity and universality. Finally this simulation results and other Domestic and foreign research or boiler operation situation can support each other, Simulative every point temperature of furnaceand the measurement results of actual operation boiler within 50℃,this article’ s mathematical model, physical model and research method are more reasonable.In this paper, the boundary conditions and process in the boiler furnace has been certain simplified and assumed, using the data from actual users research compared with the simulation results to verify, and then adjust the assumption that continue to simulate repeatedly, so repeatedly until the simulation results conform to the real situation, it can ensure the correctness of the follow-up study. Then change each boiler structure, respectively, through the simulation results of temperature field, velocity field, heat flow and pressure field analysis the impact on the process of boiler through the simulation results of temperature field, velocity field, heat flow and pressure field, to determine the impact of hearth structure on the performance of the boiler. Simulation results show that :When the Grate Angle is 13°,too big or too small front arch angle were bad before the ignition; the projection of front arch is helpful for increasing the boiler volume, and it also can improve the boiler ignition function, but the projection of front arch’s size also do not need be too large, otherwise it will waste steel and reduce the heat transfer between the flue gas and boiler wall; Decorate burner band in the arch area is necessary, but not necessarily to be full of arch zone, in burning high arch area can make use of water wall to reduce flue gas temperature to alleviate coking problem; Lower rear arch export very beneficial to improve the effect of the boiler ignition, it also can increase the combustible gas burning in the hearth, but the too low rear arch export will reduce the heat transfer effect of flue gas in the furnace; rear arch appropriate to reduce the overall height can improve the coal burning, but there is no effect even adverse instead when the rear arch is too low lead to braised fire burning happened; The ignition of herringbone rear arch compared with the traditional arch is more advantageous, but the effect is modest, and the herringbone of the rear arch itself can not enhance the burning in primary zone and the ash area. Finally, through the simulation results, the paper puts forward the reasonable range of values of each structure about this power type boiler, it provides basis and guidance for the future development, design and retrofit of large reciprocating boiler, and laid the foundation for the deep step of large reciprocating grate boiler research, and the paper also provides the reference for the research of other type boiler.