共查询到18条相似文献,搜索用时 125 毫秒
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本文对浓淡型双调风旋流燃烧器的空气动力场和气固两相流特性进行了详细的理论分析。并在分析中分别改变二、三次风的旋流强度,以考察各射流的调节特性。从中发现:三次风旋流强度的变化是影响回流区变化的主要因素;因为采用分级送风,射流前期的混合主要是在二、三次风之间。燃烧器一次风管内装有煤粉收集器,煤粉在一次风管内被惯性分离,形成了沿圆周方向煤粉气流浓淡分股;由于一次风出口加装了稳燃环,煤粉有向中心汇集的趋势;稳燃环可实现高煤粉浓度、高温、高湍动度的着火与稳燃以及挥发份剧烈的高温裂解。同时对双调风旋流燃烧器的设计特点和降低NOx生成的机理做了一定的理论分析。 相似文献
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直流二次风率对径向浓淡旋流煤粉燃烧器空气动力特性的影响 总被引:1,自引:0,他引:1
本文阐述了径向浓淡旋流煤粉燃烧器的基本原理,通过在一台410t/h的锅炉上的冷态,热态实验,研究了直流二次风率对燃烧器空气动力特性的影响,得到了直流二次风率与射流的扩展角,中心回流区直径及长度,一,二次风混合的关系,以及对燃烧器高效,稳燃,低污染,防结渣及防高温腐蚀性能的影响。 相似文献
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Low NOx burner and air staged combustion are widely applied to control NOx emission in coal-fired power plants. The gas-solid two-phase flow, pulverized coal combustion and NOx emission characteristics of a single low NOx swirl burner in an existing coal-fired boiler was numerically simulated to analyze the mechanisms of flame stability and in-flame NOx reduction. And the detailed NOx formation and reduction model under fuel rich conditions was employed to optimize NOx emissions for the low NOx burner with air staged combustion of different burner stoichiometric ratios. The results show that the specially-designed swirl burner structures including the pulverized coal concentrator, flame stabilizing ring and baffle plate create an ignition region of high gas temperature, proper oxygen concentration and high pulverized coal concentration near the annular recirculation zone at the burner outlet for flame stability. At the same time, the annular recirculation zone is generated between the primary and secondary air jets to promote the rapid ignition and combustion of pulverized coal particles to consume oxygen, and then a reducing region is formed as fuel-rich environment to contribute to in-flame NOX reduction. Moreover, the NOx concentration at the outlet of the combustion chamber is greatly reduced when the deep air staged combustion with the burner stoichiometric ratio of 0.75 is adopted, and the CO concentration at the outlet of the combustion chamber can be maintained simultaneously at a low level through the over-fired air injection of high velocity to enhance the mixing of the fresh air with the flue gas, which can provide the optimal solution for lower NOx emission in the existing coal-fired boilers. 相似文献
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In a gas/particle two-phase test facility, a three-component particle-dynamics anemometer was used to measure the characteristics of gas/particle two-phase flows in a 29 megawatt (MW) pulverized coal industrial boiler equipped with a new type of swirling pulverized coal burner. The distributions of three-dimensional gas/particle velocity, particle volume flux, and particle size distribution were measured under different working conditions. The mean axial velocity and the particle volume flux in the central region of the burner outlet were found to be negative. This indicated that a central recirculation zone was formed in the center of the burner. In the central recirculation zone, the absolute value of the mean axial velocity and the particle volume flux increased when the external secondary air volume increased. The size of the central reflux zone remained stable when the air volume ratio changed. Along the direction of the jet, the peak value formed by the tertiary air gradually moved toward the center of the burner. This tertiary air was mixed with the peak value formed by the air in the adiabatic combustion chamber after the cross-section of x/d = 0.7. Large particles were concentrated near the wall area, and the particle size in the recirculation zone was small. 相似文献
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单角试验炉煤粉射流着火可视化试验研究 总被引:2,自引:0,他引:2
本文通过一个图像采集与处理系统,将单角试验炉煤粉射流着火火焰锋面从背景中分离出来。将火焰锋面到燃烧器出口的最近距离定义为着火距离,对一种烟煤的试验研究结果表明,随着煤粉浓度的提高,其平均着火距离明显缩短。具有较高稳定性的钝体燃烧器的煤粉射流着火,倾向于在分离射流的外侧首先出现。 相似文献
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研究表明,煤粉气流着火存在最佳煤粉浓度,在最佳浓度时火焰传播速度和温度可达到最大值,试验得知难燃煤粉气流从喷嘴出口的最佳风、粉重量比接近1.0时着火、燃烧稳定。将一次风粉混合物通过喷嘴前的分离器,分离成超浓和稀淡两股,分别送入炉膛四角内外并列下倾布置的对应喷嘴,形成炉膛中央的浓粉区,近墙四周为富氧淡粉的“风包粉”气流,构成下射“W”形新的切圆旋转燃烧,利于难燃煤及早着火、稳定燃烧、充分燃烬。文中简要介绍燃烧器设计和调控要点 相似文献
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以液排渣旋风燃烧过程为基础的煤粉低尘燃烧器可在燃烧过程实现捕渣,为工业加热提供低含尘浓度的高温火焰,是工业加热过程实现以煤代油的先进燃烧技术。根据旋流燃烧流动特点,采用能考虑非均向湍流应力的雷诺应力模型,对旋流煤粉低尘燃烧器内气流流动过程场进行数值模拟计算,计算结果与流场实验测试相吻合。研究表明,气流进入燃烧器时的旋转强度(旋流数)对燃烧器内的流动特性有很大影响,在冷态模型条件下,当旋流数在7以上时,环室回流在轴向贯穿燃烧器整个流场,有利于增加煤粉颗粒在燃烧室内的循环次数,提高灰渣捕获率;低于7时,环室回流出现阻断,不再连续,易造成煤粉颗粒直接逸出,对燃烧及灰渣捕获不利。随旋流数增加,燃烧器出口处中心回流率增大,对炉膛高温烟气的抽吸作用增强。 相似文献