The Numerical Simulation On Micronized Coal Reburning Technology For Reducing NOx Emission

Pollutant NOx emission is an increasing threat to environment and human health, which becomes an urgent problem to be solved. Coal combustion in coal-fired electrical power plant is a major source of NOx. Many efficient methods have been developed for solving the NOx emission problem in world wide, one of these is fuel reburning.The principle of the fuel reburning technology is injecting reburned fuel in poor oxidizes region to reduce the NOx. Almost all the early researches used natural gas as reburned fuel. Afterwards powdered coal is added to the reburned material library, and this is most beneficial to our country for two main reasons: (1) Our country has rich coal reserves, so using coal as reburned fuel is the good method to save the investment. (2) Our country's thermoelectric power stations mainly use coal, which provide easy available coal powder for reburning porpuse. So using this reburned fuel can avoid introducing another fuel, and therefore simply relevant equipments. At present, the research works on the fuel reburning technology is still at the exploration stage.In this paper, three dimensional numerical simulation of the micronized coal reburning process is carried out.This article to burnt coal the boiler superfine powdered coal to burn the process to carry on the three dimensional value simulations again, proposed reduces method which NOx discharged. The prime task and the conclusion are as following:Establish the numerical model. The chamber reaction and heat transfer employ non-premix combustion model, the P-1 radiation model and the single rates model. During the numerical simulation, the gas phase transportation is simulated by Realizable k-ε turbulence model; the stochastic tracking method is used in tracing the tracks of particle; The PDF method is used to simulate the gas combustion.General combustion process is simulated with those numerical models described above. The simulation results are compared with experiment results, and the two correspond very well, which improves the program's availability.Through the numerical simulation on General combustion, the research on the influences of the parameters such as coal sort, particle size and stoichiometric ratio on NOx emission has been done. Results show that NOx emissions increase obviously with stoichiometric ratio increasing; The particle size exists a critical diameter (dc).