同轴旋转分层流燃烧器空气动力场中一次风转捩长度的研究

运用CCD摄像机对同轴旋转分层流低NOx燃烧器出口空气动力特性进行了可视化研究,并对采集的图像进行了一系列处理。对一次风边界转捩长度b进行了定义,分析了一次风边界转捩长度的影响,并对其变化规律进行了研究,为同轴旋转分层流燃烧器分层机理的研究打下了基础。     

同轴旋转分层流燃烧器一次风扩展角_的实验研究

运用CCD摄像机对同轴旋转分层流低NOx燃烧器出口空气动力特性进行了可视化研究,并对采集的图像和数据进行了一系列处理.对一次风扩展角α进行了定义,分析了一、二次风量比以及一、二次风叶片的位置对一次风扩展角α的影响,并对其变化规律进行了研究,为同轴旋转分层流燃烧器分层机理的研究打下了基础.     

同轴旋转射流燃烧器空气动力场的可视化研究

对同轴旋转射流燃烧器空气动力场进行了可视化实验研究。通过图象处理得到可视区边界，即一、二次风之间的界面。运用分形理论对其分形维数进行了研究，发现在不同的一、二次风旋流强度与不同的一次风率下，分形维数变化呈现一定的分布，据此确定了分层工况。     

四角切圆锅炉同轴燃烧系统空气动力特性的研究

对300MW四角切圆煤粉锅炉采用低NOx同轴燃烧系统时炉内流场及燃烧器区域浓度场进行了冷态模化试验研究。分析了当二次风偏置角度、二次风与一次风动压比、燃尽风比率及燃尽风布置方式变化时，对炉内气流相对切圆直径、旋转动量流率矩、湍动度、一二次风混合、燃尽风穿透力等的影响，进而分析了对锅炉工作的影响。图7表4参6     

外直流内旋流同轴射流和二次风平行射流组燃烧器流动特性的研究

某电厂410 t h燃油锅炉改烧水煤浆的改造工程中,采用了外直流内旋流同轴射流和二次风平行射流组的燃烧器结构,针对该结构的单角燃烧器流动特性进行了冷态模化试验与数值模拟研究。研究结果表明:一次风喷口与中心风喷口采用外直流内旋流同轴混合射流的形式,具有很好的调节作用,有利于水煤浆的稳定着火;二次风喷口采用上下平行射流的布置方式,除了可以补充足够的空气保证燃烧外,适当的射流速度可以防止脱火和回火现象的发生,有利于稳定燃烧。图10表1参5     

侧边射流横向混合扩散特性研究

本文利用气体示踪法研究燃烧器一、二次风混合扩散特性，对弱旋流（一次风）燃烧器和直流（侧边二次风）燃烧器组成的燃烧器组各股风混合情况进行了详细研究，得出各截面混合物浓度分布规律及混合强度分布规律，分析对燃烧着火的影响，对燃烧器设计参数的选择有指导意义。     

一种用于携带流反应器试验台的煤粉燃烧器的优化设计

为了优化一种用于携带流反应器系统的煤粉燃烧器结构参数,降低氮氧化物排放,本文利用计算流体动力学软件FLUENT对该煤粉燃烧器结构参数的优化过程进行了数值模拟研究,并与试验结果进行了对比验证。结果表明,燃烧器一次风喷口采用扩口结构以及对冲二次风的引入均能有效的促进二次风与一次风煤粉的混合,增强煤粉着火及燃烧的稳定性。适当增加二次风喷口与一次风喷口的间距可以加速煤粉的燃尽。采用优化后的结构参数可以获得更低的氮氧化物排放,为基于携带流反应器系统的燃煤污染物减排研究提供了坚实的基础。     

内二次风旋流强度对PAX燃烧器出口流场的影响

使用重整化解（RNG-ASM模型，对PAX燃烧器的出口流场进行了冷态数值模拟，研究了内二次风旋流强度对PAX燃烧器的流场分布，回流区大小，回流量和扩展角的影响规律，并与试验结果进行了对比，获得了比较一致的结果，为PAX燃烧器的设计和运行提供了一定的理论基础，并进一步验证了RNG-ASM模型在模拟强旋转受限射流流场的准确性。     

切圆燃烧反切风风量与位置对炉内流场的影响

本文采用数值分析技术对大容量切圆燃烧锅炉改变燃烧器二次风反切风量以及反切风位置时的炉内流场特性进行了全三维模拟和研究，研究结果表明在燃烧器上部二次风采用反切布置的情况下．无量纲数XJ在1左右时炉膛出口残余旋转较小，炉内气流湍动混合较好，炉内气流运动稳定；研究亦表明反切风位置对炉内流场影响较大。同时，对7个电厂13台大型锅炉进行了改造效果统计，验证了数值分析的结论。     

低NOx切向燃烧系统的改造及性能优化试验

针对某电厂将亚临界直流锅炉改为亚临界控制循环锅炉,对燃烧器进行了相关改造,研究分析了燃烧器改造前、后机组运行的变化,并根据改造前、后的机组运行结果进行了改变省煤器出口氧量、改变二次风配风方式和改变SOFA风风门开度等试验.结果表明:机组在300 MW负荷下,宜采用较高的运行氧量,二次风宜采用均布配风方式,SOFA风风门宜全开以及在燃烧器布置时,底层起转二次风的偏转角与位置需与一次风的假象切圆大小相配合等.同时,对机组运行存在的塌焦现象进行了初步分析,并提出了相关解决方案.     

Flow field measurements of a series of turbulent premixed and stratified methane/air flames

This paper presents flow field measurements for the turbulent stratified burner introduced in two previous publications in which high resolution scalar measurements were made by Sweeney et al.  and  for model validation. The flow fields of the series of premixed and stratified methane/air flames are investigated under turbulent, globally lean conditions (?_g = 0.75). Velocity data acquired with laser Doppler anemometry (LDA) and particle image velocimetry (PIV) are presented and discussed. Pairwise 2-component LDA measurements provide profiles of axial velocity, radial velocity, tangential velocity and corresponding fluctuating velocities. The LDA measurements of axial and tangential velocities enable the swirl number to be evaluated and the degree of swirl characterized. Power spectral density and autocorrelation functions derived from the LDA data acquired at 10 kHz are optimized to calculate the integral time scales. Flow patterns are obtained using a 2-component PIV system operated at 7 Hz. Velocity profiles and spatial correlations derived from the PIV and LDA measurements are shown to be in very good agreement, thus offering 3D mapping of the velocities. A strong correlation was observed between the shape of the recirculation zones above the central bluff body and the effects of heat release, stoichiometry and swirl. Detailed analyses of the LDA data further demonstrate that the flow behavior changes significantly with the levels of swirl and stratification, which combines the contributions of dilatation, recirculation and swirl. Key turbulence parameters are derived from the total velocity components, combining axial, radial and tangential velocities.     

合成气低旋流燃烧器设计与流动结构的分析

设计了一个合成气低旋流燃烧器,采用PIV技术对不同负荷下的冷态流场进行了测量,并比较分析了不同中心射流流速对旋流流场的影响.结果表明:流场中出现中心回流区时的旋流数与中心流速无关,高旋流与低旋流的分界点为S＝0.7;流场中的轴向速度、径向速度和湍动能均关于燃烧器中心轴线对称;中心轴线上无量纲轴向速度的分布与中心射流流速(负荷)无关,燃烧器出口下游形成一个发散低速区,有利于稳定充分燃烧;随中心射流速度的增大,径向速度成正比增大,湍动能明显增加.     

旋流燃烧器壁温计算数学模型

对旋流燃烧器轴向壁温分布数学模型做了介绍。用此模型可计算出燃烧器出口壁温与炉温的关系,并通过试验验证了该数学模型的合理性。     

Experimental study on the interactions for bluff-body and swirl in stabilized flame process

This paper focuses on investigating the interaction effects for swirl and bluff-body in stabilized flame process. Particle image velocimetry was used to measure velocity fields in three burners. First, the comparison of flames in bluff-body stabilized burners with and without swirl is presented. The results of the experiments present the variations of bluff-body stabilized flame when swirl is added into burner: the maximum reverse flow velocity and the maximum mean average radial velocity decrease; the maximum radial rootmean squared fluctuating (rms) velocity increases; the values of the axial velocity peak on the side of nozzle axis are lower, and the distance between the peak and centerline is bigger; the location of the maximum radial rms velocity moves to the outlet of annular air-flow from central recirculation zone (CRZ). Then, the comparison of flames in swirl burners with and without bluff-body is provided. The results of the experiments show the changes of swirling flame when bluff-body is added into swirl burner: the air vortex in the CRZ moves to the burner; the peak values of axial mean and rms velocity decrease; the distance between centerline and the mean axial and rms velocity peak increase; the peak of mean radial velocity decreases, and the peak of rms raidial velocity increase. The data from this experiment can also be established as benchmarks for the development and validation of combustion numerical simulations.     

The influence of swirl burner structure on the gas/particle flow characteristics

Improvements were made to a low-NO_x 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-NO_x 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 NO_x emissions.     

带钝体的旋流燃烧器出口气相流场数值模拟

应用重整化群k-ε模型和雷诺应力模型,在弱旋和强旋两种状态下,对带钝体的旋流燃烧器进行了冷态气相数值计算,弱旋流动以重整化群k-ε模型计算结果为参考,强旋流动以雷诺应力模型计算结果为参考,对比了燃烧器出口轴向平均速度和切向平均速度变化.模拟结果可以为燃烧器的设计和运行提供依据.     

采用旋流拱顶燃烧器的W型锅炉炉内流动特性

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。     

中心风对径向浓淡旋流煤粉燃烧器燃烧的影响

通过冷态PDA试验,研究了中心风对燃烧器出口气固流动特性的影响;并结合1台670t/h锅炉的工业性试验,说明了中心风对径向浓淡旋流煤粉燃烧器的燃烧有很重要的调节作用,为设计和运行提供了参考依据。图10参4     

Combustion in swirling flows: A review

Swirling flows have been commonly used for a number of years for the stabilization of high-intensity combustion processes. In general these swirling flows are poorly understood because of their compelexity. This paper describes the recent progress in understanding and using these swirling flows. The main effects of swirl are to improve flame stability as a result of the formation of toroidal recirculation zones and to reduce combustion lengths by producing high rates of entrainment of the ambient fluid and fast mixing, particularly near to the boundaries of recirculation zones. Two main types of swirl combustor can be identified as follows:The Swirl Burner. Here swirling flow exhausts into a furnace or cavity combustion occurs in and just outside the burner exit.The Cyclone Combustion Chamber. Here air is injected tangentially into a large, usually, cylindrical chamber and exhausts through a centrally located exit hole in one end. Combustion mostly occurs inside the cyclone chamber.Initially the isothermal performance of swirl combustors is considered, and it is demonstrated that, contrary to many previous assumptions, the flow is often not axisymmetric but three-dimensional time-dependent. Under most normal nonpremixed combustion conditions, the swirling flow returns to axisymmetry, although there is still a residual presence of the three-dimensionality, particularly on the boundary of the reverse flow zone. Swirl increases considerably the stability limits of most flames; in fact with certain swirl burners, the blow-off limits are virtually infinite. Cyclone combustion chambers have large internal reverse flow zones which provide very long residence times for the fuel/air mixture. They are typically used for the combustion of difficult materials such as poor quality coal or vegetable refuse. In contrast to the swirl burner which usually has one central toroidal, recirculation zone, the cyclone combustor often has up to three concentric toroidal recirculation zones. Sufficient information is also available to indicate that stratified or staged fuel or air entry may be used to minimize noise, hydrocarbon, and NO_x emissions from swirl combustors.