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1.
煤粉浓淡旋流燃烧器喷口气固两相流动的数值模拟   总被引:2,自引:1,他引:1  
在实验基础上,运用PNG-ASM和FCFSRT模型对煤粉旋流浓淡燃烧器的气固两相流进行数值模拟,并与实验结果进行对比,得出了合理的颗粒速度场和浓度场;比较和计算了浓缩和未浓缩的颗粒场特性,说明了浓淡分离燃烧器的浓淡燃烧的机理;最后对浓淡分离燃烧器煤粉混合特性作了数值模拟,指出了煤粉浓淡混合的区域。  相似文献   

2.
旋流浓淡煤粉燃烧器出口区域冷态两相流场实验研究   总被引:1,自引:0,他引:1  
采用三维相位多普勒颗粒分析仪(PDPA)对旋流浓淡煤粉燃烧器出口区域冷态两相流动特性进行了实验研究,获得了该燃烧器在不同旋流叶片开度、不同煤粉浓缩构件遮盖度、不同旋流二次风和直流二次风配比下的气固两相流场和浓度场的分布规律,并进行了讨论分析。  相似文献   

3.
在径向浓淡旋流煤粉燃烧器的基础上,本文提出了一种新型燃烧器-惯性浓淡旋流煤粉燃烧器,即在燃烧器一次风通道中加入煤粉浓缩器,并将其置于燃烧器喷口较近的位置,一次风粉经过煤粉浓缩器后,形成了由燃烧器中心向外煤粉浓度由高向低的分布趋势,依靠煤粉颗粒的惯性,将这种分布趋势一直保持到燃烧器出口。针对一台燃用烟煤的50t/h煤粉炉的特点,给出了该燃烧器的布置,介绍了改造前后的运行情况。  相似文献   

4.
一种用于蜗壳式旋流煤煤燃烧器改造的新技术   总被引:2,自引:0,他引:2       下载免费PDF全文
我国现运行的旋流燃烧器的蜗壳型燃烧器,本文从机理上分析了蜗壳型燃烧器存在的问题及径向浓淡旋煤粉燃烧器的特点,并在一台210MW的机组上对这两种旋流燃烧技术进行了比较,结果表明,径向浓淡旋流煤粉燃烧器是一种同时具有高效,稳燃,低污染,防结渣及高温腐蚀且调节灵活的新一代旋流燃烧器。  相似文献   

5.
一种新型旋流燃烧器的工作特性研究   总被引:1,自引:1,他引:0  
提出了一种具有新型结构的浓淡式旋流燃烧器,其出口射流由浓淡一次风、内外二次风组成,喷口为特制结构.采用热线风速仪对燃烧器模型出口空气动力场参数进行了测试,同时以颗粒捕集法为手段对一次风粉混合物在经过燃烧器后的气固分离效果进行了试验研究.结果表明:新型燃烧器具有优越且稳定的空气动力场,能够强化回流,提高轴线附近湍动度水平,有利于改善着火条件,抑制NOx污染物的形成;煤粉浓缩装置对实现浓淡分离的作用显著,燃烧器出口浓淡比可达4∶1以上.  相似文献   

6.
径向浓淡旋流煤粉燃烧器的工业性试验研究   总被引:10,自引:1,他引:9  
李争起  吴少华 《动力工程》1998,18(4):63-67,85
该文对径向浓淡旋流煤粉燃烧器设计中的一些问题进行了探讨,并在燃用贫煤的670t/h锅炉及燃用烟煤的410t/h锅炉上进行了冷态及热态试验。结果表明:新型燃烧器是同时具有高效,稳燃,低污染,防结渣及防高温腐蚀性能的新一代旋流煤粉燃烧器。  相似文献   

7.
秦皇岛热电厂670吨_时锅炉旋流燃烧器改造探讨   总被引:2,自引:0,他引:2  
对秦皇岛热电厂2号锅炉燃烧器的技术改造结果表明,在旋流燃烧器一次风出口加装齿形煤粉增浓器,可以实现浓淡分离燃烧,提高锅炉的低负荷稳燃烧性能和效率,这种方法简单易行,值得推广并应用于旋流燃烧器的技术改造。  相似文献   

8.
一种用于蜗壳式旋流煤粉燃烧器改造的新技术   总被引:2,自引:1,他引:1  
我国现运行的旋流燃烧器多为蜗壳型燃烧器,本文从机理上分析了蜗壳型燃烧器存在的问题及径向浓淡旋流煤粉燃烧器的特点,并在一台210MW的机组上对这两种旋流燃烧技术进行了比较,结果表明:径向浓淡旋流煤粉燃烧器是一种同时具有高效、稳燃、低污染、防结渣及高温腐蚀且调节灵活的新一代旋流燃烧器。  相似文献   

9.
煤粉浓度连续可调型浓淡燃烧器及其气固两相流动特性   总被引:2,自引:0,他引:2  
针对电站锅炉燃用煤种多变和负荷多变的问题,提出了一种新型的浓淡偏差燃烧技术,即利用组合叶片的导向作用对煤粉气流进行分离浓缩的煤粉浓度连续可调型浓淡燃烧器。应用激光粒子动态分析仪对这种燃烧器进行的两相流动特性测量表明,在一定的组合叶片角度范围内,可以实现煤粉浓度的连续调节,且由于叶片的扰动作用,气相和颗粒相的湍动都能有所提高,不同粒径颗粒的分布也发生了变化。  相似文献   

10.
采用三维相位多普勒颗粒分析仪(PDA)对旋流浓淡燃烧器出口区域两相流动特性进行了实验研究,获得了该燃烧器在不同旋流叶片开度、旋流二次风和直流二次风配比下的气固两仃流场和浓度场的分布规律,并且对这些分布规律进行了分析。  相似文献   

11.
220t/h煤粉锅炉的煤粉仓改造及将一层常规煤粉燃烧器改为浓稀相燃烧器,使燃烧稳定,适于低负荷运行,达到节油目的。  相似文献   

12.
Improvements were made to a low-NOx axial swirl burner (LNASB), aimed at mitigating slagging in a 600-MWe boiler burning bituminous coal. The new design is referred to as improved low-NOx axial swirl burner (ILNASB). This paper describes investigations of the influence of swirl burner structure on the gas/particle flow characteristics using a three-dimensional particle-dynamics anemometer. In comparing results from both ILNASB and LNASB, a central recirculation zone is seen to form in the region x/d = 0.1–0.3 within the ILNASB. This zone had shifted from the region between primary and secondary air in LNASB to a region between inner and outer secondary air. In the vicinity of the burner outlet, particle volume flux is reduced significantly in the central recirculation zone. In contrast, this flux is high near the central axis in ILNASB, thus concentrating a great fraction of pulverized coal near the central axis. Form the study, the gas/particle flow characteristics of the ILNASB show that the improved burner has the ability to ease slagging and reduce NOx emissions.  相似文献   

13.
可调浓度煤粉浓淡燃烧器的数值模拟   总被引:9,自引:0,他引:9  
采用包括脉动频谱随机轨道模型等气固多相流模型,对新型撞击可调浓度煤粉浓淡燃烧器内部的气相固多相流动进行了数值模拟。研究来流速度,撞击块高度,隔板位置等因素对气相速度场,隔板两侧配风均匀性、颗粒浓度、浓淡分离比的影响,并和仪器模化实验进行对比,计算结果和实验吻合较好,通过分析浓淡分离过程中若干问题的机理,得到了具有工程应用价值的结论。  相似文献   

14.
杨茉  康张阳  郭春笋 《动力工程》2012,32(8):623-628
通过数值计算方法研究了弯管和文丘里管组合结构燃烧器的浓淡分离特性,分析了煤粉颗粒直径和煤粉密度变化对燃烧器出口浓淡分离特性的影响.结果表明:弯管和文丘里管组合结构的燃烧器既可以实现浓淡分离,又可以达到煤粉浓侧气流不贴壁和中间给粉的效果;当煤粉颗粒直径为10μm时,浓淡分离效果不明显;当颗粒直径为50μm时,分离效果较好,并且浓度核心的最大煤粉浓度随着St的增大而增大;当颗粒直径为100μm时,随着St的增大,出现了多个浓度核心.  相似文献   

15.
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   

16.
Lean premixed swirl combustion is widely used in gas turbines and many other combustion Processes due to the benefits of good flame stability and blow off limits coupled with low NOx emissions. Although flashback is not generally a problem with natural gas combustion, there are some reports of flashback damage with existing gas turbines, whilst hydrogen enriched fuel blends, especially those derived from gasification of coal and/or biomass/industrial processes such as steel making, cause concerns in this area. Thus, this paper describes a practical experimental approach to study and reduce the effect of flashback in a compact design of generic swirl burner representative of many systems. A range of different fuel blends are investigated for flashback and blow off limits; these fuel mixes include methane, methane/hydrogen blends, pure hydrogen and coke oven gas. Swirl number effects are investigated by varying the number of inlets or the configuration of the inlets. The well known Lewis and von Elbe critical boundary velocity gradient expression is used to characterise flashback and enable comparison to be made with other available data.Two flashback phenomena are encountered here. The first one at lower swirl numbers involves flashback through the outer wall boundary layer where the crucial parameter is the critical boundary velocity gradient, Gf. Values of Gf are of similar magnitude to those reported by Lewis and von Elbe for laminar flow conditions, and it is recognised that under the turbulent flow conditions pertaining here actual gradients in the thin swirl flow boundary layer are much higher than occur under laminar flow conditions. At higher swirl numbers the central recirculation zone (CRZ) becomes enlarged and extends backwards over the fuel injector to the burner baseplate and causes flashback to occur earlier at higher velocities. This extension of the CRZ is complex, being governed by swirl number, equivalence ratio and Reynolds Number. Under these conditions flashback occurs when the cylindrical flame front surrounding the CRZ rapidly accelerates outwards to the tangential inlets and beyond, especially with hydrogen containing fuel mixes. Conversely at lower swirl numbers with a modified exhaust geometry, hence restricted CRZ, flashback occurs through the outer thin boundary layer at much lower flow rates when the hydrogen content of the fuel mix does not exceed 30%. The work demonstrates that it is possible to run premixed swirl burners with a wide range of hydrogen fuel blends so as to substantially minimise flashback behaviour, thus permitting wider used of the technology to reduce NOx emissions.  相似文献   

17.
采用旋流拱顶燃烧器的W型锅炉炉内流动特性   总被引:1,自引:0,他引:1  
采用旋流燃烧器,可以强化燃烧器出口煤粉气流的着火,配合采用燃烧器内部分级燃烧方式后,也有利于降低污染气体的排放。但采用旋流燃烧器后,由于W型锅炉燃烧的特殊性,给锅炉的设计和运行带来了新的情况,如对旋流燃烧器在W型锅炉拱顶采用旋流燃烧器后炉内的空气动力特性不能很好得到掌握,不但得不到旋流燃烧器所带来的优点,还会引起很多问题。本文对采用旋流燃烧器的W型锅炉的炉内多相流动特性进行分析,并与相应的采用直流燃烧器的W型锅炉进行对比,指出在采用直流燃烧器的W型锅炉设计中常采用的参数在采用旋流燃烧器时可能会出现的问题,并提出了改进的方法。  相似文献   

18.
在不同中心扩口角度的情况下,通过对径向浓淡旋流煤粉燃烧器的冷态PDA试验,研究了燃烧器出口速度、粒径及浓度分布,得出了中心扩口角度对燃烧器出口区域气固流动特性的影响规律,并分析了中心扩口对燃烧器性能的影响,为工程应用和优化设计提供了参考性依据。  相似文献   

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