Simulation Of Harmful Pollutants In The Exhaust Gas Of Coal-fired Boiler

In recent years, coal-fired boilers with high-capacity and high-parameter develope rapidly, and its technology of production is close to the international advanced level. However, its energy consumption is also very high, and brings about heavy pollution. With increasingly stringent emission standards of the promulgation and implementation, sharply substantial modifications need to meet the standards. Then, reducing emissions by optimizing combustion conditions based high combustion efficiency has important significance.In this paper, XD-240/9.8-M (Q) CFB boiler is taken as a research object. The FLUENT 6.3 software is used for numerical simulation. The model is firstly discredited before simulation. two-equation model, two-equation model of competition, turbulent non-premixed combustion model, kinetics/diffusion-controlled reaction rate model, P-1 model, stochastic particle model are used in the simulation of turbulent flow of the gas phase, gas (volatile) precipitation the gas phase (volatile) burning, combustion of the coal, the internal boiler radiation, the trajectory of the particle in the simulation, respectively.Finally, the distribution of the temperature, velocity and concentration under different conditions are obtained and analyzed. By comparing with the operating parameters of the model in actual condition, the numerical results prove to be reasonable. When the velocity of primary air is 3 m/s, and the velocity of secondary air is 60 m/s, the combustion effect of the boiler is better, the outlet concentration of oxygen is 2.64%, and less contaminants meanwhile:the concentration of NO and CO2 are 1142mg/m3, 3210 mg/m3, respectively.After that, it makes a detailed analysis about numerical simulation results, and then gets the impact factors of the mechanism of pollutants formation and the impact of the combustion conditions on the concentration of pollutants which exist in the exhaust gas. The analysis results can be used to optimize the design of the furnace, and can be used in the equipment modification process. Moreover, it has certain significance on the actual production of exhaust gas purification process.