煤粉燃烧火焰辐射光谱实验研究

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。     

关于煤粉火焰稳定性和煤粉预燃室及火焰稳定船的作用

沿用预混可燃气体的火焰稳定理论常不能正确地分析煤粉火焰的稳定问题,不宜于用来指导煤粉燃烧设备的设计和运行。本文着重分析了在中国电站煤粉锅炉中已广泛采用的煤粉预燃室和新型火焰稳定船式煤粉燃烧器中煤粉颗粒的运动和燃烧过程,认为在燃烧设备中组织好含煤粉的气流的运动,使能在燃烧室中形成局部的高煤粉浓度、高温和合适氧浓度的区域,成为稳定的煤粉着火有利区,是保持煤粉火焰稳定的原则。此煤粉火焰稳定原则可以阐明各种保持煤粉火焰稳定的技术措施,也有利于分析和开发新的煤粉燃烧技术。     

粉煤燃烧的新概念——粉气分离

一、前言 近年来,我国在煤粉燃烧技术发展方面取得了丰硕的成果,陆续开发成功了多项煤粉稳定燃烧装置如钝体煤粉燃烧器、大速差同向射流直流式煤粉预燃室和火焰稳定船式直流煤粉燃烧器以及夹心风浓缩燃烧器等。这些新型燃烧器的应用,大大改善了劣质煤的燃烧过程,煤粉燃烧着火提前,火焰稳定性加强,使劣质煤的燃烧利用达到了一个新的水平。     

煤粉射流火焰的DNS研究

本文用直接数值模拟(DNS)的方法对煤粉气固两相射流燃烧进行了研究。文章介绍了DNS的数值计算方法,包括气相、颗粒相的控制方程以及煤粉燃烧模型。分析了煤粉射流燃烧火焰的结构形态,发现火焰区域中存在三种火焰形态,通过火焰特性的统计研究,发现虽然火焰形态不同,但是其燃烧特性相似,非预混火焰占主导地位。分析火焰释热量,发现上游处单颗粒燃烧释热量较小,条带状释热量占24%,对下游稳定火焰的形成至关重要。     

高浓度煤粉火焰中煤质对最佳煤粉浓度的影响

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。     

花瓣燃烧器低负荷运行理论与应用的研究

本文应用贴体坐标结构化网格对复杂曲面的花瓣燃烧器进行了三维(360°)煤粉燃烧的数值模拟.给出了在75%BMCR和55%BMCR工况下花瓣燃烧器的流场和浓度场,重点分析了花瓣燃烧器的稳燃原理和特性.计算结果表明,在花瓣稳燃器的作用下,煤粉气流进入炉内能立即在瓣后的径向回流区内着火燃烧,并在此区域形成稳定的"值班火焰",为整个风粉气流的着火燃烧提供稳定的热量来源.有利于低挥发分煤在广泛负荷范围内的稳定着火和完全燃烧.     

燃烧状态及煤粉粒径对火焰光谱的影响

本文利用CCD光纤光谱仪,对不同燃烧状态下的煤粉火焰光谱进行测量。发现通过光谱法测得的火焰温度和使用热电偶测得的火焰温度存在一定的偏差。光谱法的温度较热电偶的温度高100-700℃,燃烧条件变差时热电偶的温度下降,光谱法的温度升高,两者偏差增大,光谱法温度的波动范围增加。随着一次风煤粉浓度下降, K的发射谱线强度下降。相同燃烧条件下,煤粉细度提高使得光谱法测得的温度下降,温度波动加剧。     

胶体CdSe量子点的色度学特性研究

使用化学胶体法合成了CdSe量子点，研究了样品的荧光量子产率，发现随CdSe量子点粒径的增大，荧光量子产率存在先增大后减小的现象.研究了CdSe量子点的色度学特性，通过对不同尺寸、不同粒径分布范围的CdSe量子点色度坐标的计算，讨论了粒径分布范围对其荧光颜色饱和度的影响，解释了为何难以获得高颜色饱和度的绿光量子点.利用红、蓝两种不同尺寸的量子点配制出白光样品，提出了估计配色后样品色度坐标的经验公式，结果显示白光样品色度坐标的实验值与经验公式估计值基本一致.     

湍流煤粉火焰中多相燃烧的跨尺度模拟方法及应用

通过"湍流涡团尺度"与"边界层反应尺度"的关联,建立了湍流煤粉火焰中多相燃烧的跨尺度模拟方法。该方法能够预报湍流脉动宏观规律对静止颗粒边界层内气相反应(如挥发分火焰、CO火焰)的影响。将该方法用于煤粉旋流燃烧数值模拟中,结果显示:与完全忽略边界层气相反应的单膜模型相比,跨尺度模拟的预报结果与Lockwood实验数据有更好的符合。     

煤粉低尘燃烧器热态试验研究

以液排渣旋风燃烧技术为基础的煤粉低尘燃烧器可在燃烧过程实现捕渣,为工业加热提供含尘浓度低的高温火焰,是工业加热过程实现以煤代油的先进燃烧技术。本论文介绍了新型煤粉低尘燃烧器的热态燃烧试验研究结果,该燃烧器采用端面旋流进风,煤粉和一次风在旋转气流外层送入,分级燃烧等技术。热态试验研究表明,采用上述技术的煤粉低尘燃烧器具有燃烧完全,捕渣率高,NOx排放浓度低等特点。     

Spherical turbulent flame propagation of pulverized coal particle clouds in an O2/N2 atmosphere

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.     

Effect of ammonia/oxygen/nitrogen equivalence ratio on spherical turbulent flame propagation of pulverized coal/ammonia co-combustion

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.     

船形体煤粉燃烧器NO_x生成特性的研究

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...     

光谱法测量煤粉火焰温度和黑度的研究

利用由ＣＣＤ线阵组成的微型光纤光谱仪研制了现场火焰光谱测量装置。通过测量３５０ＭＷ电站锅炉的煤粉火焰从 ５３３ｎｍ至１０５０ｎｍ波段的辐射光谱,发现煤粉火焰的辐射非常接近灰体辐射。根据这一特点,从维恩公式出发,利用最优化方法处理测得的火焰辐射光谱信号,得到了火焰的温度和黑度。     

A three mixture fraction flamelet model for multi-stream laminar pulverized coal combustion

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.     

单只水平浓缩煤粉燃烧器在1MW燃烧试验台上的试验研究

单只水平浓缩煤粉燃烧器在１ＭＷ燃烧试验台上的试验研究孙绍增，吴少华，李争起，杨明新，王新雷，陈力哲，庞丽君，邢春礼，朱彤，孙恩召，秦裕琨（哈尔滨工业大学动力工程系哈尔滨１５０００１）关键词：水平浓淡燃烧，煤粉燃烧器，稳燃，低ＮＯ_ｘ一、引言电力工业对?..     

Experimental and numerical investigations on the interactions of volatile flame and char combustion of a coal particle

The model that takes chemical reactions, heat and mass transfers in the boundary layer of the particle into account simultaneously, is developed for simulating the combustion of a pulverized coal particle. The FTIR in situ temperature-measurements and the comparison between numerical simulations for the pulverized coal and the devolatilized char show that the volatile flame induces the combustion of the primary product of surface oxidation CO. Due to the influence of volatile flame, the char particle can be ignited at temperature lower than its heterogeneous ignition temperature, which elucidates the physical essence of joint hetero-homogeneous ignition mode discovered by Jüntgen.     

多功能旋流燃烧器的工业性试验研究

秦皇岛热电厂2＃锅炉燃烧不稳定、燃烧效率低等问题主要是由于燃烧器的一次风管道结构不合理造成的。本文采用多功能旋流燃烧器的设计思想对旋流燃烧器进行了技术改造和工业性试验研究。结果表明,改造后的旋流燃烧器其着火点提前,并且仅改造6只主力燃烧器就可以使锅炉在50％负荷时达到不投油而稳定燃烧,排烟温度、飞灰含碳量和NOx排放量明显下降。     

煤粉旋风燃烧过程流场特性研究

煤粉旋风燃烧器可用于工业加热过程,实现以煤代油,本论文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,对煤粉旋风燃烧器内气流流动过程场进行数值模拟计算,流场计算结果表明,燃烧室几何参数对其内部的流动特性有很大的影响。计算结果与流场实验测试相吻合。