沥青搅拌站煤粉旋流燃烧室的数值模拟研究
Numerical simulation of the swirling pulverized coal combustor used for asphalt mixing plants
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摘要: 燃煤加热节约沥青搅拌站的运行成本。设计了出力为4 t/h的煤粉旋流燃烧室及其加热系统,并对燃烧室开展数值模拟研究。结果表明,煤粉颗粒燃烧室内迅速着火燃烧,燃烧室内速度场和温度场分布较为对称;旋流燃烧室内流场由旋流燃烧器和切向喷入燃烧室的二次风共同主导,当燃烧室切向进入的二次风与中心射线的偏置角不小于60°,一次风率在0.15~0.20,旋流燃烧室内流场合理,煤粉的燃烧效率可达97%~99%,NO_x排放浓度在650 mg/Nm~3左右,具有较高的负荷调节能力。模拟结果论证了在沥青搅拌站上使用煤粉旋流燃烧的可行性并提供了一定设计指导。Abstract: Coal-fired heating will greatly save the operating costs in an asphalt mixing plant operating costs. In this pa- per,we designed swirl combustor burning 4 t / h pulverized coals for the heating system of asphalt mixing plant and nu- merically studied the combustion characteristic of the swirl chamber was numerically studied. The results revealed that pulverized coal particles were rapidly heated up and stably burnt in the combustor. The distributions of the velocity and temperature fields were rather symmetric. The velocity filed of swirling combustor was determined by the swirl burner and the secondary airs which tangentially shooting into the combustor. When the offset angle between the secondary air and the radial line was greater than 60° and the primary air rate was 0. 15-0. 20,the flow field in the combustor soun- ded reasonable,with a combustion efficiency of 97% -99% ,the NOx concentration at the exit around 650 mg / Nm3 and excellent load adjustability. Simulation results demonstrated that the swirling pulverized coal combustion is feasible for the asphalt mixing plant and provided some guidance for the combustor design.