Numerical Simulation Research On Tyre Reburning

With the rapid economic development in China, energy and environmental problems are becoming increasingly serious. And the harm of NOX, which is generated during the combustion process of the coal, to the environment and human beings can not be ignored. At present, reburning technology has become one of the most effective low NOX combustion technologies. In this paper, numerical simulation researches about the tyre reburning have been conducted on the basis of the previous research of the domestic and foreign scholars.Numerical simulations about the conventional coal combustion and tyre reburning, for which, coal is the primary fuel, are conducted on a 80 KW pulverized coal combustion test facility. Comparative analyses with experimental results are made and the results show that, with the application of the selected model and boundary conditions, the simulated results and experimental results are consistent for temperature distributions in the furnace and NOX emissions. Within the research conditions, the denitration rate and CO emission are both high for the conditions with higher reburning fuel fraction. The burning effect is the best for the condition that the reburning fuel fraction is set to 17.4% after considering both the denitration rate and burnout degree of the fuel in the furnace. Compared with the conventional combustion, which does not adopt the reburning technology, the simulated reburning denitration efficiency reaches 81.08%.On the basis of the above research, comparative reseaches about the coal reburning and tyre reburning are made under the same conditions, and the results show that the denitration effect of the tyre is better than that of the coal as a result of the higher volatile content of the tyre. Tyre reburning denitration rate is 14.91% higher than that of the coal under the optimum condition.Further detailed researches about the tyre reburning are conducted on the coal combustion test facility above with the application of the orthogonal simulation design method, and the simulated indicators, denitration rate and CO emission are both considered and the calculated results show that, the influences ofthe reburning fuel fraction, the excess air coefficient at the reburn zone and the temperature of the secondary air on the tyre reburning effect weakens according to the order, and the reburning fuel fraction of the tyre also affects the degree of the burnout strong. And the case under the conditions that the reburning fuel fraction set to 20%, excess air coefficient set to 0.87 and the temperature of the secondary air set to 500 K, is the best, for which, the fuel in the furnace can burnout and the denitration effect is the highest. The denitration rate reaches 82% compared with the conventional case which does not use the reburning technology.Numerical simulation researches about the tyre reburning on the 600 MW supercritical down-fired boiler are conducted with the application of the results above. Results show that with the use of the tyre reburning technology, NOX emissions can be reduced efficiently, and with respect to the conventional coal combustion, which does not usethe reburning technology, NOX removal rate reaches 60.31%.