【作者】 刘胜利；

【导师】 胡念苏；

【作者基本信息】 武汉大学 ， 动力工程， 2004， 硕士

【摘要】 近年来,随着浓淡偏差技术在直流燃烧器上的应用,更加有利于煤粉着火和燃尽以及降低NO_x的排放。我国科学工作者在原有的垂直浓淡燃烧技术的基础上开发研制了水平浓淡燃烧技术。水平浓淡燃烧技术在一些电站锅炉上的应用,很好地解决了低挥发分煤的着火、稳燃和燃尽的问题。同时,该技术的应用还提高电站锅炉调峰能力、减少了电站锅炉低负荷运行时的助燃油。汉川电厂针对该厂300MW锅炉低负荷运行时稳燃能力差,不具有调峰能力的情况,进行了锅炉燃烧器系统的改造。 本文应用FLUENT软件对该厂300MW锅炉煤粉燃烧器和浓缩器内的气相流场、颗粒轨迹和浓度分布进行了数值模拟,运用数值模拟的结果估计了燃烧器的磨损情况,提出了燃烧器优化设计的方案。 在改变燃烧器的结构、不改变其它运行参数的情况下,对气相和气固两相进行模拟分析。数值模拟的结果表明,钝体以及各级叶片对浓侧出口气流速度有较大影响,而对淡侧气流速度影响不大。对于浓侧出口和淡侧出口,高速区都集中在中间区域,轴向速度由中间区域向外围逐渐减小。在燃烧器出口钝体下游轴向速度为负,形成回流区。在气固两相模拟中,由于颗粒相的加入,导致燃烧器出口浓淡风比RQ接近于1,这表明颗粒相对浓淡风比有极大影响。在钝体两侧煤粉浓度比较大,且气流以一定角度冲刷,因此在钝体两侧煤粉对其冲刷严重,磨损加剧。钝体和三级叶片对燃烧器的浓缩比和浓缩率有较大影响,应该采取有效措施延长钝体和三级叶片的寿命。 研究表明,四级叶片的浓缩器的浓淡风比较理想,浓缩器的浓缩率较高,有利于改进燃烧器的性能,建议优先选用四级叶片的浓缩器结构。 通过对汉川电厂#3炉低负荷调峰技术改造进行燃烧调整试验,了解和掌握了#3炉燃烧系统在不同负荷下的运行特性及影响因素。同时,本文还研究了该锅炉的负荷与NO_x排放量之间的关系。最后,提出了该炉在低负荷下的最优化运行方案,为#3炉燃烧系统的优化运行提供了依据。更多还原

【Abstract】 In recent years, with the application of dense-dilute technology in straight-flow burners, it can do better in firing of pulverized coal and decreasing the emission of NOx. The boiler designers developed horizontal dense-dilute burners based on vertical dense-dilute burners. The application of horizontal dense-dilute technology in some boilers has resolved many problems, such as the fire, self-supporting burning and burn-up problem of low volatile coal. At the same time, the technology has enhanced the ability of peaking and reduced fuel oil at low load. In view of improving the flame stability in low load, a retrofit of the 300MW boiler coal burner is carried out in Hanchuan Power Station.The paper simulates the gas phase flow field, particle track and concentration distribution in the coal burner and concentrator of the 300MW boiler in Hanchuan power plant by the software of FLUENT CFD. estimates the erosion state and optimizes the design plan of the burner to the concentrator was also estimated.Under the condition that the configuration of the burner was changed and other operating parameters stay the same, the simulation analysis to the gas phase and solid phase was carried out. Results showed that the bluff-body and blades had large influences on the exit airflow velocity of the fuel-rich side while little on the fuel-lean side. To both the rich side and lean side exit, the high speed area is concentrated on the middle area while the axial velocity decreases gradually from the middle area to the periphery. At the exit of the bluff-body, recirculation area is formed because of the negative downstream axial velocity. In the simulation of the gas-solid phase, because of the introduction of the particle phase, the ratio of the fuel- rich stream and fuel- rich stream at the exit of the burner is approaching to 1, which shows that particle phase has significantly affected the ratio of the fuel-rich and lean-fuel stream. On both sides of the bluff-body there exists high concentration and the airflow impact the bluff-body with a certain angle, which causes severe erosion of the two sides of the bluff-body. Bluff body and blades have large influences on the concentration ratio of burner, so effective measures should be taken to extend the life of the bluff-body and blades.The concentrator with four blades has an ideal Fuel-rich-to-fuel-lean air ratio and ahigh concentrating ratio, therefore is beneficial to the performance of the burner. It is suggested that four blades are of the first choice for the concentrator.Through combustion debugging test of the No. 3 boiler in Hanchuan power plant for enhancing ability in low load operation. The paper analyzes the relationship between load and NOx emission and put forward some suggestions for optimizing operation at low load.更多还原