Pulverized Coal Reburning Numerical Simulation On A 410t/h Boiler For Low NOx Emission

Energy and pollution were important factors affecting society development. The combustion of fuels generate SO₂ and NO_x emissions, which can lead to serious atmosphere pollution .Coal was the important fuel for china , and most of coal was used in power plant . Control of the combustion and pollution of power plant were important for the sustainable development of human society.A Corner-tangential-boiler of 410t/h in Guohua Beijing thermal powerplant was studied in the thesis. Firstly, optimizing operation was carried on boiler for de-NOx emission; secondly, numerical simulation was made by Fluent software, the calculation results were consistent with experiments. The retrofit scheme of reburn was put out which ascended the upper primary wind. The operation simulation of retrofit system revealed that conditions after reconstruction excelled than the old.Optimizing operation of boiler was studied by analyzing test data of several boiler conditions. The results revealed that adjustments of air distribution and feed powder could optimize the operation of boiler. After optimizing operation, the quantum of NOx decreased and the boiler efficiency increased, the most optimizing air distribution and feed powder was resist for every boiler. An optimizing method was put out in the thesis.The simulation calculation of boiler operation was discussed in detail. Numerical simulation is based on fine grid. The study focused on the aspects such as grid-build, grid quality and its influence on calculation. A fine grid was put out in thesis which could benefit the convergence. The calculation results were consistent with the experiments data. So the simulation results could guide the practical operation.Finally the thought and method of design were expatiated from theory. The feasible design was put out which ascended the upper primary wind as reburning-spout and ascended the upper secondary wind as OFA. The simulation results were discussed in detail about fluid flow, pressure field, temperature filed, the distribution of species, and the production of NOx. After retrofitting, the boiler operated stably and the circle radius was under control as there is not combustion sticking to the wall's surface; the temperature field was uniformity; complete combustion was reached as the carbon in fly was not found in simulation results; the emission of NOx decreased obviously and the reduction efficiency was 43.3%. To sum up, the simulation results revealed that the retrofit system was successful.