Optimization Simulation Of A 600MW Opposed Swiring Boiler Under Different Loads

Coal-fired power is still the main source of electricity production for quite a long time.As environmental and energy problems are becoming increasingly prominent,and the state has introduced strict environmental standards,coal-fired power plants have encountered unprecedented technological challenges.For coal power enterprise to search for economy and meet the great demand of environmental protection,energy-saving operation technology is particularly important.In this paper,to analysis the combustion and search optimal operation under different loads,and to improve the operation economy of the boiler,the numerical simulation was carried out for a 600 MW swirling opposed utility boiler in Datong.The geometric model and mesh were established by the pre-processing software Gambit,and the simulation calculation was taken by using the commercial computational fluid dynamics software Fluent to generate pulverized coal particles reports,and CFD-POST is used to carry on the post-processing analysis to obtain the velocity field,temperature field and each species field.Firstly,the operating parameters of all loads were obtained through the field test,and the 550 MW condition is used as a contrast case to verify the correctness of the model.Based on the model,the combustion optimization of boiler is studied.The combustion optimization variables under different loads include the ratio of over-fire air(OFA),the ratio of the upper OFA to the lower,and the ratio of internal to external OFA.The study of combustion optimization was based on the single factor change of each variable.The results show that when the ratio of OFA increases,the lean oxygen condition intensifies in the main combustion zone,and incomplete combustion is increased,so it causes the burnout rate of pulverized coal decreased,but also reduces the production of NO_x;when the ratio of the upper OFA to the lower increases,it causes the OFA to mix later with the main flue gas,and unburned carbon in burnout zone is not fully burned,which reduce the burnout rate.Meanwhile,the air classification is strengthened,which makes the NO_x emissions decreased;when the ratio of internal to external OFA decreases,the burnout rate of pulverized coal will increase first and then decrease,due to its impact on the mixture of the over fire air and the main flue gas.Based on the combustion optimization simulation under various loads,considering the mutual restraint between burnout efficiency and NO_x emissions,the optimal interval of each operation variable under the corresponding load is given.