Study On The Adaptability Of Coal Combustion Of 300MW Coal-fired Boiler

At present,China ’s coal consumption is huge and coal supply is often in short supply during the operation of power plants.In response to this situation,most power plant boilers use coal-blended combustion to ensure the safe operation of boiler units.Mixed admixture can not only reduce the dependence on a single coal type,but also reduce the operating cost of the power plant.In this paper,a 300 MW coal-fired boiler is used as the research object,and numerical simulation is used to study the adaptability of coal blending and simulation study of combustion optimization.First,GAMBIT software was used to establish the geometric model of the boiler and the grid was divided.After verification of grid independence,FLUENT software was used to perform numerical simulation on the boiler BMCR operating conditions,and the accuracy of the model was verified by comparison with actual operating data.On this basis,the analysis of variable operating conditions was carried out,and the effects of operating load,primary air rate,burner level density ratio on the combustion of the furnace were changed in turn.Secondly,coal blending schemes were formulated,including blending between coal types with large differences,blending between coal types with small differences,and blending between same coal types.In order to explore the combustion characteristics and emission characteristics of coal-fired boiler units when they burn coal with different volatile content,and ensure that the volatile content of the mixed coal is within the lean coal range,the blending ratio is changed by changing the blending ratio.Volatile content.First select the mixed combustion condition 2C for combustion optimization simulation research.By changing the parameters such as the primary air rate and the burner level dilute ratio,and comparing and analyzing the simulation results before and after the optimization,the optimized furnace exit smoke temperature and NOx emissions are obtained.Both have decreased,and the pulverized coal burnout rate has increased slightly.Finally,the simulation analysis of all the coal blending schemes of the boiler unit under the optimal operating parameters shows that when the blending of coals with large difference characteristics is blended,when the volatile content of the mixed coal is within the range of lean coal,the fuel When the volatile content of the mixed coal is close to the volatile content of the designed coal,the combustion characteristics and emission characteristics are better.When the volatile content of the mixed coal is close to the lean coal range,the greater the volatile content of the mixed coal,the NOx emissions The larger,there is no obvious difference in pulverized coal burnout rate;when coals with smaller difference characteristics are mixed,the change of volatile content of the mixed coal has no significant effect on the temperature field and oxygen concentration field,but with the combustion The volatile content of blended coal gradually decreases,and the NOx emissions gradually increase,so it is necessary to pay attention to the selection of the blending ratio;when the same coal is blended,the NOx emissions gradually increase as the volatile content of the blended coal is increased.Decrease,but the pulverized coal burnout rate also gradually decreases.The NOx emissions of different blending ratios vary greatly,but the pulverized coal burnout rate does not have a large difference.Therefore,the blending of the same coal type should be Take the NOx emissions as the main reference value.