【作者】 苏伟；

【导师】 李瑞扬；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2010， 硕士

【摘要】 随着国民经济快速发展，我国对电力需求迅速增长，燃用贫煤、无烟煤电站容量剧增。W火焰锅炉采用了长火焰、分级送风、煤粉浓缩等技术手段，非常适用于大型燃用贫煤、无烟煤机组。目前我国已投用了80多台W火焰电站锅炉，积累了不少实际运行经验，但对该锅炉尚缺深入的研究，而对带旋流燃烧器W火焰锅炉的还很少。针对某电厂燃无烟煤W火焰锅炉，根据模化原理设计了一个燃烧器冷态试验台和一个带旋流燃烧器的W火焰锅炉冷态实验台，利用热线风速仪对燃烧器出口流场和W火焰锅炉炉内流场进行实验研究，分析不同外二次风叶片角度对炉内流场的影响。采用热线风速仪对旋流燃烧器模型进行了冷态试验研究，得出了不同外二次风叶片角度对出口流场的影响。叶片角度为25°和35°时，燃烧器出口无中心回流区，煤粉主要依靠外回流区点火。在叶片角度为45°和55°时出现中心回流区，同时，射流刚性减弱，轴向速度衰减快。采用热线风速仪对一台300MWe采用旋流燃烧器的W火焰锅炉模型进行了冷态试验研究，得出了不同外二次风叶片角度对炉内空气动力场的影响。在外二次风叶片角度为20°时，射流穿透深度大，与拱下的乏气及分级风很合好，有利于煤粉的燃烧，但气流有冲刷喉口的迹象。叶片角度为25°和30°时，气流行程缩短，与分级风的混合减弱，拱下回流区变小，冲刷喉口的现象消失。叶片角度为35°时，气流穿透深度进一步减小，气流与乏气的混合减弱。叶片角度为40°和50°时，在燃烧器出口区域出现中心回流区，气流在燃烧器喷口附近即行转弯向上，造成火焰短路。综合考虑以上情况，锅炉在运行过程中，外二次风叶片角度在25°和30°之间为最佳。更多还原

【Abstract】 In China, with the national economy rapidly developing, the societydemands on more and more electricity, so that the capacity of power stationburning lean coal or anthracite leaps quickly. Down-fired boiler specially suits forlarge scale burning lean coal or anthracite power station, because of adoptinglong-flame, air zoning and high concentration factor of pulverized coal. Atpresent, more than eighty down-fired boilers are operating in many Chineselarge-scale power stations. Many operation experiences are accumulated in China,but the research of down-fired boiler is not in-depth enough. Indeed, there are notmany lucubrate results on the down-fired boiler adopting swirl burners.A pilot-scale of 1:4 of a swirl burner used in down-fired boiler and a scale of1:10 of down-fired boiler model with swirl burners were designed and producedaimed at a full-scale utility boiler for cold experimentation by modeling theory.Using an IFA300 constant temperature anemometer system, the air flowcharacteristic of the outlet of the swirl burner and the inner of the furnace werestudied to analyze the influence of different outer secondary air vane angles onthe flow characteristics in the furnace.Using an IFA300 constant temperature anemometer system, cold airexperiments on a quarter-scaled burner model were also carried out to investigatethe influence of various outer secondary air vane angles on the flowcharacteristics in the burner nozzle region. No central recirculation zone appearedfor vane angles of 25°and 32.5°. Most of the pulverized-coal was ignited in theexternal recirculation zone. For vane angles of 45°and 55°, a central recirculationzone could be observed, and air flow rigidity and axial velocities decreasedrapidly.Using an IFA300 constant temperature anemometer system, cold airexperiments on a scale-model of a down-fired pulverized-coal 300 MWe utilityboiler with swirl burners were performed to investigate the influence of outersecondary air vane angles on the flow characteristics in the furnace. For vaneangle of 20°, the reach of the downward airflow is deep and the mixing with ventair and staged-air is good, thereby favoring coal combustion, but at the expense airflow washing out at the entrance of the upper furnace. For vane angles of25°and 30°, the reach of the downward airflow is short, mixing with thestaged-air weakens, and thus the recirculation zone below the arches is small,although washing out at the entrance ceases. The reach of the airflow furthershortens, and the mixing of the airflow and vent air is weaker for a 35°vaneangle. At even larger vane angles of 40°and 50°, the recirculation zone appearsin the burner nozzle region, and the airflow is directed upwards near the burnernozzle region, creating a short flame circulation. Considering all of the above,conditions with a vane angle setting in the range of 25°and 30°are considered asoptimal in the operation of the boiler.更多还原