【作者】 徐斌；

【导师】 朱群益； 李争起；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2007， 硕士

【摘要】 我国电力工业以燃煤发电为主,中心给粉旋流煤粉燃烧技术具有高效、稳燃、低NOx排放、防结渣以及防高温腐蚀等优点,本文在某300MW墙式布置燃用烟煤电站锅炉上,对下层8只燃烧器分别采用锅炉原型的增强型双调风燃烧器和改造所采用的中心给粉旋流燃烧器进行了实验室冷态试验,锅炉的冷态、热态试验,以深入了解中心给粉旋流燃烧器的燃烧特性。通过冷态和热态试验研究表明,增强型双调风燃烧器在外二次风叶片角度为45°的运行工况下,出口区域没有形成中心回流区,锅炉低负荷稳燃能力差。当叶片角度调整为30°时,出口区域形成中心回流区,煤粉能及时着火和稳定燃烧,但不利于防止侧墙水冷壁结渣和高温腐蚀。冷态试验得出了外二次风叶片角度、外二次风量和一次风量对中心给粉燃烧器的中心回流区和扩展角的影响规律,通过燃烧器区域的热态试验得出了外二次风叶片角度和给煤量对燃烧器燃烧特性的影响规律。研究表明,当外二次风叶片角度为35°时,中心给粉燃烧器的中心回流区尺寸和扩展角的角度是合适的,既能防止相邻两只燃烧器之间相互干扰,还能保证煤粉的及时着火和稳定燃烧,同时还有利于抑制NOx的生成。对比试验结果得到,相比于增强型双调风燃烧器,在沿射流方向的燃烧器中心区域,中心给粉燃烧器的烟气温度、升温速率、CO浓度、CO2浓度和碳燃尽率较高,而O2浓度和NOx浓度较低;沿径向方向靠近侧墙水冷壁区域,中心给粉燃烧器的O2浓度较高,而气体温度、CO浓度和CO2浓度较低。在锅炉底层燃烧器采用中心给粉燃烧器后,锅炉燃烧效率从96.73%提高到97.09%,,NOx排放量从843.55mg/m3降低到727.67mg/m3(折算到O2=6%),锅炉可在110MW负荷下不投油稳定运行。因此,中心给粉旋流燃烧器不仅提高了锅炉的低负荷稳燃能力,还降低了NOx排放量,更有效防止了侧墙水冷壁结渣和高温腐蚀。更多还原

【Abstract】 In China, electricity is generated mainly by coal combustion. The central-fuel-rich swirl coal combustion (CSCC) burner has the advantages of high combustion efficiency, stable flame, low NOx emission, less slagging and high-temperature corrosion on the water-cooled wall. Experiments were performed to investigate the combustion characteristics of CSCC burners of a 300-MW wall-fired utility boiler burning with bituminous. The eight enhanced ignition-dual register burners (EI-DRB) in the bottom row of the furnace were retrofitted to the CSCC burners. The experiments consisted of two parts: the cold-flow experiments in pilot scale test facilities modeling from these two types of burners, the full-scale aerodynamic field and combustion experiments of these two types of burners in the utility boiler.The both results of pilot-scale and full-scale cold flow field experiments show that with EI-DRB burner, the central recirculation zone does not exist in the near-burner region when the outer secondary air vane angle is set to 45°. It is the main reason why the boiler can not be stably operated without auxiliary fuel oil at a low load. When the vane angle is set to 30°, there is a stable central recirculation zone in the near-burner region. It is advantageous for the pulverized coal ignition and combustion, but disadvantageous for the lessening of slagging and high-temperature corrosion on the side wall.Through the cold-flow experiments, the effects of the outer secondary air vane angle, the outer secondary air ratio and the primary air ratio on the central recirculation zone size and the divergent angle of CSCC burner were obtained.And though the full-scale combustion experiments, the effect of the outer secondary air vane angle and coal-feed rate on the combustion characteristics of CSCC burner in the near-burner region were presented. The results show that when the outer secondary air vane angle of CSCC burner is set to 45°, the size of the central recirculation zone and the divergent angle are appropriate. It can prevent the jet flows issuring from the adjacent burners from interfering, and makes the coal ignite in time and burn stably, and can also reduce the NOx formation. For CSCC burners, local mean CO concentrations, gas temperatures and their rate of increase are higher and mean concentrations of O2 and NOx along the jet in the burner region are lower compared to EI-DRB burners. Moreover, the mean O2 concentration is higher and the gas temperature and mean CO concentration are lower in the side wall region. For CSCC burners in the bottom row, the combustion efficiency of the boiler increases from 96.73% to 97.09%, and NOx emission decreases from 843.55 to 727.67 mg/m3 at 6% O2 compared to EI-DRB burners and the boiler operates stably at 110 MW without auxiliary fuel oil. Thus, the CSCC burners can improve the flame stability when the boiler operates at a low load, and can also reduce the NOx emission and prevent the side water-cooled wall from slagging and high-temperature corrosion.更多还原