Numerical Study Of Low NO_x Reformation Of An 600MW Rwirl-opposed Coal-fired Boiler

With the increasingly severe environmental problems, especially a large area of fog and haze raging in recent years in North China, emissions of air pollutants has aroused great concern. In this context, for the coal-fired power plants, the national level is proposed ultra-low emissions strategies. This makes the transformation of coal-fired power plants to reduce emissions is extremely urgent. In this paper, specific low-NO_x combustion renovation project to Wangqu 600 MW supercritical once-through boiler plant as the research object, by changing the overfire air vents to take the wind rate and overfire air vents of the structure, the number of the rotary blade angle, of NO_x generated during the combustion numerical simulation analysis, and guidance boiler low NO_x burner modifications based on simulation results.Firstly, according to the mass, momentum, energy conservation and component constraints, the control equations are built. The solution process simulation calculations are determined based on the numerical simulations of common solving process. By comparing the conventional gas-phase turbulence model, gas-solid flow model,combustion models, radiation heat transfer model and NO_x reaction models, the specific model of low NO_x numerical simulation is determined.Secondly, an overview of the status of Wangqu 600 MW Power Plant Unit 2 boiler is gone through. On this basis, the calculation conditions and boundary conditions of numerical simulation, simulation OFA boiler, boiler overfire air optimization design simulation to Wangqu 600 MW Power Plant Unit 2 boiler numerical simulation is analyzed. And the followings are drawn: overfire air vents to take the wind rate and overfire air vents of the structure, the number of the rotary blade angle duct resistance are related. Removing the necking and canceling the swirling wind strength, increasing the number of overfire air vents will be good for reducing the fly ash and NO_x emissions.After the increase in the number of overfire air vents, the rotary blade when fully open,the wind rate of OFA can reach 38%, which is higher than the design wind rate, this can be assigned by adjusting the throttle opening control air flow, so as to achieve the design air rate of 30%.Finally, according to the conclusions, the numerical simulations are given for low nitrogen wangqu 600 MW Power Plant Unit 2 boiler combustion rehabilitation programs,the reconstruction program Calculation method for thermal performance, and the furnace temperature distribution, concentration distribution of oxygen, CO NO_x concentration distribution and concentration distribution of the simulation results were analyzed.The simulation results show: After the transformation, in the furnace to form a good aerodynamic field, burner zone temperature distribution is very uniform, no significant temperature zone outlet temperature, oxygen distribution is uniform. Formed in the burner zone to restore a central area, which significantly inhibited the formation of NO_x.As the air classification effect depth, NO_x emissions lower than the original proposal,and still be able to ensure a high burnout rate of pulverized coal. In the 600 MW load conditions, NO_x and CO emission concentration after conversion to achieve the design goal, boiler fly ash carbon content and mechanical incomplete combustion heat loss is not higher than the existing boiler operation level, and can effectively reduce colorectal Wall slag and high temperature corrosion tendency.