共查询到17条相似文献,搜索用时 182 毫秒
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齿形中心扩锥对旋流燃烧器气固流动影响的PDA试验研究 总被引:1,自引:0,他引:1
1前言旋流燃烧器依靠高温回流区做为稳定的热源,使煤粉气流及时着火并稳定燃烧,燃烧器单独组织燃烧,不互相影响,燃烧器区域的气固流动特性决定了燃烧器的性能。燃烧器的喷口结构对其气因流动特性有重要影响山。本文提出了齿形中心扩锥结构(如图l所示)。2实验方法及结果分析试验采用三维激光粒子动态分析仪(简称三维PDA),实验台系统主要由送风机、吸风机、给粉机、燃烧器模型、试验段、旋风分离器等组成,试验段为一竖直放置的筒体,直径为4800mm,燃烧器模型安装在简体上部中心位置,最外层扩口端部与筒体内壁平齐,沿射流流动方… 相似文献
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高浓度煤粉火焰对装有浓淡燃烧器的煤粉燃烧系统的着火具有十分重要的作用。本文在一简化的燃烧系统和一配备浓淡燃烧器的1 MW切圆煤粉炉内进行了大量试验,研究了煤质对最佳煤粉浓度C_(opt)的影响规律,在该最佳煤粉浓度下燃烧系统具有最高的火焰温度及最低的飞灰含碳.试验结果表明:对于所有的高浓度煤粉火焰均存在一最佳的煤粉浓度,着火特性差的无烟煤的最佳煤粉浓度显著高于着火特性更佳的烟煤,该最佳煤粉浓度随着煤质发热量Q与挥发分V乘积的增大而降低,并存在一经验公式C_(opt)=1.069-0.051·10~(-5)·V·Q。 相似文献
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船形体煤粉燃烧器NO_x生成特性的研究 总被引:1,自引:0,他引:1
船形体煤粉燃烧器NO_x生成特性的研究钟北京,徐旭常(清华大学煤的高效低污染燃烧国家重点实验室北京100084)关键词煤粉燃烧器,“三高区”原理,NO_x1前言我国电力工业的发展主要依赖于以煤为主要燃料,采用粉状燃烧方式的火力发电。1992年我国年产煤... 相似文献
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煤粉燃烧火焰辐射光谱实验研究 总被引:1,自引:0,他引:1
针对煤粉燃烧辐射光谱问题,利用光纤光谱仪对煤粉平面火焰炉实验装置煤粉燃烧火焰辐射光谱进行了测量,详细分析了煤粉辐射光谱特征,并基于普朗克辐射传热定律,通过对光谱仪波长响应特性的标定,得到火焰绝对辐射强度随波长的分布情况,进而利用最小二乘法获得火焰温度与辐射率参数,由此提出基于煤粉燃烧火焰辐射光谱测量的火焰参数测量方法。利用该方法对不同燃烧条件下煤粉燃烧参数进行测量,开展了不同燃烧参数下煤粉火焰辐射光谱实验研究,研究结果表明:煤粉燃烧火焰辐射在200~1 100 nm波段具有较强且连续的光谱特征,基于普朗克辐射定律与最小二乘法可实现煤粉燃烧火焰温度与辐射率的测量;煤粉燃烧火焰辐射光谱在590,766,769和779 nm附近可见明显的Na和K等碱金属痕量元素原子光谱发射谱线,并且这些原子谱线的出现与火焰温度有关;随着煤粉浓度的提高,虽然燃烧温度变化不大,但由于火焰辐射率的增加,造成辐射光谱强度的大幅提升。这对锅炉煤粉燃烧优化具有重要参考价值。 相似文献
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Longchao Yao Chenyue Wu Yingchun Wu Linghong Chen Jun Chen Xuecheng Wu Kefa Cen 《Proceedings of the Combustion Institute》2019,37(3):2911-2918
Devolatilization is an important process in pulverized coal combustion because it affects the ignition, volatile combustion, and subsequent char burning and ash formation. In this study, high-speed digital in-line holography is employed to visualize and quantify the particle and volatile evolution during pulverized coal combustion. China Shanxi bituminous coal particles sieved in the range of 105–154 µm are entrained into a flat flame burner through a central tube for the study. Time-resolved observations show the volatile ejection, accumulation, and detachment in the early stage of coal combustion. Three-dimensional imaging and automatic particle extraction algorithm allow for the size and velocity statistics of the particle and stringy volatile tail. The results demonstrate the smaller particle generation and coal particle swelling in the devolatilization. It is found that the coal particles and volatiles accelerate due to the thermal buoyancy and the volatiles move faster than the coal particles. On average, smaller particles move faster than the larger ones while some can move much slower possibly because of the fragmentation. 相似文献
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Xu Wen Yujuan Luo Haiou Wang Kun Luo Hanhui Jin Jianren Fan 《Proceedings of the Combustion Institute》2019,37(3):2901-2910
A three mixture fraction flamelet model is proposed for multi-stream laminar pulverized coal combustion. The technique of coordinate transformation is utilized to map the flamelet solutions from a unit pyramid space into a unit cubic space to improve the stability of the simulation. The validity of the three mixture fraction flamelet model was assessed on different configurations, including a laminar counterflow pulverized coal/methane flame and a laminar piloted pulverized coal jet flame. The flamelet predictions were compared to the reference results of the detailed chemistry solutions. For the counterflow flame, it was found that the flame temperature and major species mass fractions are correctly predicted by the three mixture fraction flamelet model. However, discrepancies are observed for combustion-mode-sensitive species such as CO and H2 in the premixed combustion region. The thermo-chemical quantities in the char surface reaction zone cannot be correctly predicted if the mixing between the char off-gas stream and other streams is neglected. For the piloted jet flame, it was shown that the stable thermo-chemical variables can be correctly predicted at the upper and middle stream locations. However, at the downstream location, discrepancies can be observed in certain regions. Overall, the validity of the three mixture fraction flamelet model for multi-stream pulverized coal combustion is confirmed and its performance in turbulent pulverized coal combustion will be tested in future work. 相似文献
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Yu Xia Khalid Hadi Genya Hashimoto Nozomu Hashimoto Osamu Fujita 《Proceedings of the Combustion Institute》2021,38(3):4043-4052
Because ammonia is one of the most promising candidates for energy carrier in the future, various applications of ammonia as a fuel are currently considered. One medium for utilizing ammonia is by introducing it to coal-fired boilers. To the best of our knowledge, this paper is the first to report the fundamental mechanism of the flame propagation phenomenon for pulverized coal/ammonia co-combustion. The effects of the equivalence ratio of the ammonia-oxidizer mixture on the flame propagation velocity of pulverized coal/ammonia co-combustion in turbulent fields were clarified by the experiments employing a unique fan-stirred constant volume chamber. The flame propagation velocities of pulverized coal/ammonia co-combustion, pure ammonia combustion, and pure pulverized coal combustion were compared. As expected, the flame propagation velocity of pulverized coal/ammonia was higher than that of the pure pulverized coal combustion for all conditions. However, the comparison of the flame propagation velocities of pulverized coal/ammonia co-combustion and that of the pure ammonia combustion, revealed that whether the flame propagation of the pulverized coal/ammonia was higher than that of the pure ammonia combustion was dependent on the equivalence ratio of the ammonia-oxidizer. This unique feature was explained by a mechanism including three competing effects proposed by the authors. In the ammonia lean condition, the positive effects, which are the strong radiation from the luminous flame and the increment of local equivalence ratio by the addition of volatile matter, are larger than the negative effect, which is the heat absorption by coal particles in preheat zone. In the ammonia rich condition, the effect of an increment of the local equivalence ratio by the addition of volatile matter turns into a negative effect. Consequently, the negative effects overcome the positive effect in the ammonia rich condition resulting in a lower flame propagation velocity of pulverized coal/ammonia co-combustion. 相似文献
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Khalid Hadi Ryo Ichimura Nozomu Hashimoto Osamu Fujita 《Proceedings of the Combustion Institute》2019,37(3):2935-2942
The present study aims to clarify the effects of turbulence intensity and coal concentration on the spherical turbulent flame propagation of a pulverized coal particle cloud. A unique experimental apparatus was developed in which coal particles can be dispersed homogeneously in a turbulent flow field generated by two fans. Experiments on spherical turbulent flame propagation of pulverized coal particle clouds in a constant volume spherical chamber in various turbulence intensities and coal concentrations were conducted. A common bituminous coal was used in the present study. The flame propagation velocity was obtained from an analysis of flame propagation images taken using a high-speed camera. It was found that the flame propagation velocity increased with increasing flame radius. The flame propagation velocity increases as the turbulence intensity increases. Similar trends were observed in spherical flames using gaseous fuel. The coal concentration has a weak effect on the flame propagation velocity, which is unique to pulverized coal combustions in a turbulent field. These are the first reports of experimental results for the spherical turbulent flame propagation behavior of pulverized coal particle clouds. The results obtained in the present study are obviously different from those of previous pulverized coal combustion studies and any other results of gaseous fuel combustion research. 相似文献
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Jun Hayashi Nozomu Hashimoto Noriaki Nakatsuka Hirofumi Tsuji Hiroaki Watanabe Hisao Makino Fumiteru Akamatsu 《Proceedings of the Combustion Institute》2013,34(2):2435-2443
Soot formation characteristics of a lab-scale pulverized coal flame were investigated by performing carefully controlled laser diagnostics. The spatial distributions of soot volume fraction and the pulverized coal particles were measured simultaneously by laser induced incandescence (LII) and Mie scattering imaging, respectively. In addition, the radial distributions of the soot volume fraction were compared with the OH radical fluorescence, gas temperature and oxygen concentration obtained in our previous studies [1], [2]. The results indicated that the laser pulse fluence used for LII measurement should be carefully controlled to measure the soot volume fraction in pulverized coal flames. To precisely measure the soot volume fraction in pulverized coal flames using LII, it is necessary to adjust the laser pulse fluence so that it is sufficiently high to heat up all the soot particles to the sublimation temperature but also sufficiently low to avoid including a too large of a change in the morphology of the soot particles and the superposition of the LII signal from the pulverized coal particles on that from the soot particles. It was also found that the radial position of the peak LII signal intensity was located between the positions of the peak Mie scattering signal intensity and peak OH radical signal intensity. The region, in which LII signal, OH radical fluorescence and Mie scattering coexisted, expanded with increasing height above the burner port. It was also found that the soot formation in pulverized coal flames was enhanced at locations where the conditions of high temperature, low oxygen concentration and the existence of pulverized coal particles were satisfied simultaneously. 相似文献