低NOx旋流燃烧器燃烧特性数值模拟研究与应用
Numerical simulation of combustion characteristics on low NOx swirl burner and its application
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摘要: 广东某660MW超临界前后墙对冲旋流锅炉在工程实际运行中发生旋流燃烧器（OPCC）大规模烧损现象，为探究旋流燃烧器烧损的原因，基于商用计算流体力学软件FLUENT对其开展数值模拟研究，采用控制变量法研究变旋流强度下该燃烧器的燃烧特性，研究表明：外二次风叶片角度为30°时无法形成中心大回流区，且煤粉提前在一次风风道中被点燃并剧烈燃烧，造成燃烧器烧毁。外二次风叶片角度为55°时旋流强度过大时则导致煤粉着火点距燃烧器喷口过近，容易造成燃烧器喷口烧毁，且高温燃烧区靠近炉内燃烧区出口处，导致大量热量被浪费；外二次风扩口增加至45°时，中心大回流区烟气量增加但湍动能下降，导致燃烧器喷口烧毁及煤粉未完全燃烧便逸出炉内燃烧区。外二次风扩口增加至55°时，炉内高温烟气倒灌进入外二次风扩口导致扩口烧毁；外二次风叶片高度降低至80mm将导致中心回流区流速因旋流强度降低而减小，造成中心大回流区气流无法托起煤粉使其在近壁处燃烧，增加炉内受热面发生高温腐蚀的概率。外二次风叶片高度增加120mm将导致中心大回流区由于长时间保持射流方向而处于“三低”状态，不利于煤粉的充分完全燃烧；外二次风叶片减小至10片或增加至15片均会引起高温燃烧区整体减小及燃烧区偏转。外二次风叶片数量减小至10片将引起燃烧器喷口处温度过高，从而增加燃烧器喷口烧毁的概率，外二次风叶片数量增加至15片将显著提升近壁面处发生高温腐蚀的概率。Abstract: The large-scale burning loss of swirl burner (OPCC) occurred in the actual operation of a 660MW supercritical opposed firing boiler in Guangdong province, In order to explore the causes of burning loss of swirl burner ,The numerical simulation is carried out based on the commercial computational fluid dynamics software FLUENT ,and studied the combustion characteristics of the burner under variable swirl intensity by using the control variable method, the research shows: When the blade angle of the external secondary air is 30 °, a large central reflux area cannot be formed, the pulverized coal is ignited and burned violently in the primary air duct in advance, resulting in the burning of the burner. When the angle of the external
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