Prediction of Excess Air Factor in Automatic Feed Coal Burners by Processing of Flame Images

In this study, the relationship between the visual information gathered from the flame images and the excess air factor 2 in coal burners is investigated. In conventional coal burners the excess air factor 2. can be obtained using very expensive air measurement instruments. The proposed method to predict ） for a specific time in the coal burners consists of three distinct and consecutive stages; a） online flame images acquisition using a CCD camera, b） extrac- tion meaningful information （flame intensity and bright- ness）from flame images, and c） learning these information （image features） with ANNs and estimate 2. Six different feature extraction methods have been used： CDF of Blue Channel, Co-Occurrence Matrix, L-Frobenius Norms, Radiant Energy Signal （RES）, PCA and Wavelet. When compared prediction results, it has seen that the use of co- occurrence matrix with ANNs has the best performance （RMSE = 0.07） in terms of accuracy. The results show that the proposed predicting system using flame images can be preferred instead of using expensive devices to measure excess air factor in during combustion.

Experimental study and numerical simulation of gas-particle flows with radial bias combustion and centrally fuel rich swirl burners

Numerical simulation is applied to gas-particle flows of the primary and the secondary air ducts and burner region, and of two kinds of swirl burners. The modeling results of Radial Bias Combustion (RBC) burner well agreed with the data from the three-dimensional Phase-Doppler anemometry (PDA) experiment by Li, et al. The modeling test conducted in a 1025 t/h boiler was to study the quality of aerodynamics for a Central Fuel Rich (CFR) burner, and the Internal Recirculation Zone (IRZ) was measured. In addition, gas-particle flows with a CFR burner were investigated by numerical simulation, whose results accorded with the test data fundamentally. By analyzing the distribution of gas velocity and trajectories of particles respectively, it is found that the primary air’s rigidity of CFR burner is stronger than that of RBC burner, and the primary air mixes with the secondary air later. Furthermore, high concentration region of pulverized coal exists in the burner’s central zone whose atmosphere is reduced, and trajectories of particles in IRZ of CFR burner are longer than that of RBC burner. They are favorable to coal’s ignition and the reduction of NOx emission.

On the Role of Electrodes in Introducing Airflow Distortion in Residential Oil Burners

Computational Fluid Dynamics (CFD) simulations of airflow through a retention head residential oil burner were carried out to study the velocity field near and around the fuel spray. The simulations revealed (as expected, based on some previous experimental measurements) the velocity flow field to be far from axisymmetric. Moreover, the center of the swirling airflow was found to be at some radial distance away from the physical centerline of the flame tube. Since it was suspected that the two electrodes just upstream of the retention ring of the burner might be responsible for this flow distortion, additional CFD simulations were then carried out for the cases of no electrodes and 4-electrodes. The results clearly show that all flow distortions (velocity deviations from axisymmetric value) vanish when no electrodes are present and that the flow distortions are reduced by a factor of 2 when two additional dummy electrodes (for a total of 4 electrodes) are included in the burner design. Furthermore, for the 4-electrode case, the eccentricity of the swirling airflow is reduced by almost a factor of 3 as compared to the base design case of 2-electrodes.

Comparative Appraisal of Response Surface Methodology and Artificial Neural Network Method for Stabilized Turbulent Confined Jet Diffusion Flames Using Bluff-Body Burners

The present study was conducted to present the comparative modeling, predictive and generalization abilities of response surface methodology (RSM) and artificial neural network (ANN) for the thermal structure of stabilized confined jet diffusion flames in the presence of different geometries of bluff-body burners. Two stabilizer disc burners tapered at 30° and 60° and another frustum cone of 60°/30° inclination angle were employed all having the same diameter of 80 (mm) acting as flame holders. The measured radial mean temperature profiles of the developed stabilized flames at different normalized axial distances (x/dj) were considered as the model example of the physical process. The RSM and ANN methods analyze the effect of the two operating parameters namely (r), the radial distance from the center line of the flame, and (x/dj) on the measured temperature of the flames, to find the predicted maximum temperature and the corresponding process variables. A three-layered Feed Forward Neural Network in conjugation with the hyperbolic tangent sigmoid (tansig) as transfer function and the optimized topology of 2:10:1 (input neurons: hidden neurons: output neurons) was developed. Also the ANN method has been employed to illustrate such effects in the three and two dimensions and shows the location of the predicted maximum temperature. The results indicated the superiority of ANN in the prediction capability as the ranges of R2 and F Ratio are 0.868 - 0.947 and 231.7 - 864.1 for RSM method compared to 0.964 - 0.987 and 2878.8 7580.7 for ANN method beside lower values for error analysis terms.

基于杯式燃烧器测试系统的灭火性能评价研究进展

杯式燃烧器试验是消防领域用于测定气体灭火剂最小灭火浓度的经典方法。自哈龙灭火剂被淘汰以来,哈龙替代物经历了不同相态的发展,促使杯式燃烧器测试系统进行相应的改进,同时基于杯式燃烧器测试系统的灭火性能评价研究也在不断拓展。综述了国内外杯式燃烧器测试系统的使用和改进研究,重点介绍了适用于气相、液相、固相和复合相灭火剂的杯式燃烧器测试系统和测试方法,分别对气相、液相、含添加剂细水雾、干粉、复合灭火剂的灭火效率进行了总结和分析,综述了各相态灭火剂灭火性能评价研究。未来,杯式燃烧器测试系统仍将不断被改善,在灭火剂筛选和灭火性能评价等方面将发挥更重要的作用。

融入激光诊断的杯式燃烧器灭火实验教学设计

设计了融入先进激光诊断系统的杯式燃烧器灭火实验装置,创设了包含基础性和探究性的层次化实验教学内容,构建了分组协作和课堂研讨相结合的实验教学模式,让学生了解杯式燃烧器的结构特点,掌握利用杯式燃烧器测量气体灭火浓度值的原理和方法,并引导他们通过激光诊断技术进一步探究灭火机理。通过实验教学,加深学生对灭火基本理论的理解,激发他们的创新思维和团队精神,为其后续的科研工作打下基础。

提高中厚板淬火炉出炉温度命中率的实践研究

某公司淬火炉因燃气种类变化对燃烧系统进行了改造,改造后出炉温度命中率波动较大,严重影响了产品性能的稳定性。通过对出炉温度命中率主要影响因素的分析,从点火电极的阳极与阴极之间距离变化、UV探头失效分析及内外温差导致烧嘴损坏三个方面提出了解决方案,实现了出炉温度命中率的大幅提升。

脉动燃烧器研究进展及其在病虫害防治中的应用

目前,Helmholtz型脉动燃烧器被广泛应用且前景良好。其具有环保节能、燃烧效率高、传热特性佳、热效率高以及排放污染少等诸多优点。将Helmholtz型脉动燃烧器应用于病虫害防治装备的研制,对稳定作物生产、提高作物品质、增加种植效益以及发展科学植保和绿色植保具有重要意义,有助于保障生态可持续。概述Helmholtz型脉动燃烧器的工作原理,梳理脉动燃烧器的研究发展现状,总结Helmholtz型脉动燃烧器在病虫害防治方面的应用研究。目前便携式脉动燃烧病虫害防治装备存在人机工程学缺陷、土壤蒸汽消毒机热动力源耦合关系不明确、脉动燃烧机理研究不够深入且脉动燃烧器结构简单、装备智能化程度低等问题。提出应用现代化技术研究脉动燃烧机理,研制脉动燃烧病虫害防治装备新型结构与机型,运用智能化、现代化技术开发大型车载式病虫害防治机械,发展脉动燃烧病虫害防治机械智能控制模块的发展对策。

辽代香炉文化元素中民族交往交流交融的历史考察

焚香习俗是我国不同地区、不同民族社会生活重要的组成部分。辽代焚香在中国焚香史上地位举足轻重,辽国人们日常生活、宗教场域、祭祀礼仪等都会焚香,焚香所用器具融合了唐、宋等中原王朝的文化特征,这些文化元素生动展现了这一时期民族间地区间的交往交流互动融合的图景,以及进而形成的多元共生的政治格局。通过对辽境有据可考的香炉进行功用的解析、交流融合元素的深度阐释,以期透过“香炉”还原当时民族交往交流交融的历史图景及共生互嵌的民族关系镜像。

车用大功率柴油燃烧器的研制

针对商用车越来越严苛的NO_(x)排放法规,解决低温冷起动阶段NO_(x)的排放问题尤为重要。设计了一种车用大功率柴油燃烧器系统,用于低温冷起动过程中快速提升排气温度,使选择性催化还原器(SCR)入口温度迅速达到尿素起喷温度。详细阐述了系统方案及核心零部件的开发。利用STAR-CCM+仿真软件,对优化结构进行点火及燃烧仿真,详细分析了燃烧状态的温度分布、柴油挂壁、碳烟分布、燃烧效率、燃烧背压等。最后经过台架试验验证,冷态世界统一瞬态循环(WHTC)工况NO_(x)转换效率达97.9%,升温能力与升温速率远超常规热管理技术,同时油耗还有一定优势。

燃气轮机中心分级燃烧器天然气掺氢燃烧的受迫振荡特性

天然气掺氢燃烧是燃气轮机机组降低碳排放重要措施之一,但掺氢燃料的组分变化会导致燃烧室火焰结构及燃烧稳定性发生变化.为分析中心分级燃烧器掺氢燃烧条件下的燃烧不稳定性问题,通过试验研究了燃烧器入口速度扰动下,不同掺氢比对中心分级掺氢燃烧的瞬态火焰结构、压力以及热释放响应的影响,并利用本征正交分解(POD)法提取了火焰脉动的特征模态,发现其主要包含火焰干涉区强脉动和轴向扰动两种模态.试验结果表明,随着掺氢体积比从0%增大到30%,火焰前沿向上游移动,两级火焰间距缩短,火焰干涉对应的脉动模态的能量占比增大,加强了压力与热释放的耦合,导致燃烧室内的压力响应增大9%,热释放响应增大37%.

Burner effects on melting process of regenerative aluminum melting furnace

According to the features of melting process of regenerative aluminum melting furnaces, a three-dimensional mathematical model with user-developed melting model, burner reversing and burning capacity model was established. The numerical simulation of melting process of a regenerative aluminum melting furnace was presented using hybrid programming method of FLUENT UDF and FLUENT scheme based on the heat balance test. Burner effects on melting process of aluminum melting furnaces were investigated by taking optimization regulations into account. The change rules of melting time on influence factors are achieved. Melting time decreases with swirl number, vertical angle of burner, air preheated temperature or natural gas flow; melting time firstly decreases with horizontal angle between burners or air-fuel ratio, then increases; melting time increases with the height of burner.

660MW高水分褐煤锅炉超低负荷运行特性研究

为揭示大容量高水分褐煤机组的超低负荷运行特性及性能优化方式,基于建立并验证的燃煤锅炉燃烧模型,研究了33%最大连续额定负荷下燃烧器运行方式对660 MW高水分褐煤锅炉炉内燃烧、传热及NO_(x)转化特性的影响。结果表明:超低负荷下炉内仍可形成良好组织的流动及燃烧场,但锅炉综合性能显著下降,如燃烧温度及受热面吸热量显著降低、炉膛出口NO_(x)排放增加等;运行4层燃烧器时投运连续的下、中间组或中间、上组燃烧器,可有效防止燃烧、传热过程的显著恶化及NO_(x)排放的明显增加;燃烧器投运层数影响锅炉综合性能,运行2层燃烧器时炉内剧烈燃烧区域过于集中,不利于维持较高的燃烧温度及传热强度,炉膛出口NO_(x)排放升高。研究结果揭示了超低负荷下燃烧器投运位置及层数对660 MW高水分褐煤锅炉综合性能的影响,可为大规模可再生能源电力并网背景下高水分褐煤机组参与深度调峰的运行调整及优化提供指导。

干煤粉气化炉烧嘴偏置角度变化下的烧嘴罩性能优化研究

介绍了华能公司IGCC机组干煤粉气化工艺,针对干煤粉气化炉一段烧嘴水平偏置改造后,产渣量大幅提升,导致烧嘴罩发生漫渣、泄漏的问题,通过采取提高烧嘴罩探入深度、优化配煤方式控制气化炉产渣量、改造粉煤给料罐底锥稳定煤线波动等措施,进一步提升了烧嘴罩运行的稳定性,基本避免了烧嘴罩发生漫渣、泄漏现象。

Unraveling the role of dual Ti/Mg metals on the ignition and combustion behavior of HTPB-boron-based fuel

Metal additives play an essential role in explosive and propellant formulations. Boron(B) is widely used in propellant applications owing to its high energetic content. The addition of B to explosives and propellants increases their energy density, making them more efficient and powerful. Nevertheless, B forms oxide layers on its surface during combustion, slowing down the combustion rate and reducing rocket motor efficiency. To overcome this issue, other metal additives such as aluminum(Al), magnesium(Mg),and titanium(Ti) are revealed to be effective in boosting the combustion rate of propellants. These additives may improve the combustion rate and therefore enhance the rocket motor’s performance. The present study focused on preparing and investigating the ignition and combustion behavior of pure hydroxyl-terminated polybutadiene(HTPB)-B fuel supplemented with nano-titanium and nanomagnesium. The burn rates of HTPB-B fuel samples were evaluated on the opposed flow burner(OFB)under a gaseous oxygen oxidizer, for which the mass flux ranges from 22 kg/(m^(2)·s) to 86 kg/(m^(2)·s). The addition of Ti and Mg exhibited higher regression rates, which were attributed to the improved oxidation reaction of B due to the synergetic metal combustion effect. The possible combustion/oxidation reaction mechanism of B-Mg and B-Ti by heating the fuel samples at 900℃ and 1100℃ was also examined in a Nabertherm burnout furnace under an oxygen atmosphere. The post-combustion products were collected and further subjected to X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM) analyses to inspect the combustion behavior of B-Ti and B-Mg. It has been observed that the B oxide layer at the interface between B-Ti(B-Mg) is removed at lower temperatures, hence facilitating oxygen transfer from the surroundings to the core B. Additionally, Ti and Mg decreased the ignition delay time of B, which improved its combustion performance.

空气射流特征对纯氨旋流燃烧火焰影响规律

氨是理想能源,为更好利用纯氨燃料,开发适用纯氨燃料的燃烧器,通过数值模拟对某10 kWth天然气旋流燃烧器进行三维建模,并对其纯氨燃烧和氮氧化物排放性能进行计算及仿真分析,探讨空气射流特性对火焰形态、温度分布、NO生成及排放的影响规律,以优化燃烧器纯氨燃烧能力。燃烧早期,旋流对燃料和空气混合影响大,而燃烧后期湍流强度对该过程影响大。发现通过增大空气射流孔面积(由12.8 mm^(2)增至19.2 mm^(2))、增加空气射流角度(由15°增至30°)均可增强旋流强度,促进燃料和空气混合,促进氨燃料快速着火和稳定燃烧,缩短着火距离。但过大的射流角度可能导致空气和燃料出现短暂分离,推迟混合过程,延长着火距离。此外,减小射流孔面积、增大射流角度还将增强燃烧器喷嘴附近湍流强度,促进氨燃料和空气混合燃耗,产生局部高温区,导致NO生成浓度升高。经对比优化,空气射流孔面积19.2 mm^(2)、射流角度15°、射流速度19.83 m/s时纯氨燃烧器实现稳定低NO燃烧,着火距离0.024 m、火焰长度0.446 m,NO生成峰值浓度和排放浓度分别降至443×10^(-6)和37.7×10^(-6)。

铅锌冶炼烧结点火炉点火过程数值模拟

为了探究铅锌冶炼工艺中烧结点火炉内点火过程的多物理场分布规律,本文以某企业带式点火炉为研究对象,构建了炉内天然气流动、燃烧与传热过程的数学物理模型,并考虑了铅锌矿料化学反应热以及料层阻力的影响,对点火炉内的点火过程进行了详细的数值模拟研究,深入分析了炉内速度场、温度场和浓度场的分布规律,评价了点火料层的温度均匀性,并分析了其产生的原因,最终总结了点火炉的优化改造建议。结果表明:点火烧嘴中高速气流相向运动形成撞击面,破坏了炉内流场的稳定性;点火段主要位于两排主烧嘴的下方料面区域;主烧嘴气流受点火烧嘴气流的影响而发生偏转,导致点火段料面存在局部低温区,不利于料层的均匀着火。

基于煤粉预气化强稳燃的快速调峰燃烧器5 MW中试研究

煤粉预气化强稳燃技术能够兼顾稳定燃烧与NO_(x)排放控制。基于此,开发了服务于电站锅炉灵活调峰的快速调峰燃烧器,并依托5 MW燃烧试验平台进行热态中试试验,对比不同负荷下的运行性能,研究燃烧器的极限稳燃负荷与快速变负荷能力。结果表明:煤粉进入燃烧器所带有的小型预气化室后发生气化反应,转化为高温燃气和炽热碳粒所组成的预热燃料。在低负荷下,预热燃料进入炉膛后将迅速燃烧,形成根部高温区,保证炉膛稳燃。随着负荷升高,预气化室内气化反应更加充分,配合回流烟气形成良好还原性气氛,实现有效降氮。在无辅助手段条件下,满负荷工况NO_(x)排放为159 mg/m^(3)(6%O_(2)),飞灰含碳率为3.4%,折算燃烧效率99.71%。在9%超低负荷下,快速调峰燃烧器仍能维持炉膛稳定燃烧,在1 h以上长时间连续运行过程中,出口氧量保持稳定。在15%~100%负荷分别用时8和9 min完成快速降负荷与升负荷过程,降、升负荷速率分别可达10.63%/min与9.44%/min。变负荷过程中炉内燃烧保持稳定,且温度分布对负荷变化的响应速度较快,验证了该燃烧器在快速调峰过程中的出色性能。

高浓度煤粉预燃式强稳燃低氮燃烧器配风组织优化

煤粉预燃低氮燃烧技术可兼顾稳定燃烧与NO_(x)排放控制,在燃煤锅炉灵活性调峰稳燃领域的应用潜力巨大。依托5 MW燃烧试验平台,研究一种带小型预燃室的高浓度煤粉预燃低氮燃烧器运行性能。通过CFD数值模拟,系统研究了一次风率、内外二次风配风与分离式燃尽风(SOFA)对燃烧器燃烧性能及污染物排放特性的影响。结合5 MW燃烧试验平台测试结果对燃烧模型进行验证验证,试验实际温度与数值计算结果的最大偏差为44℃,误差范围±3.3%,证明所选燃烧模型的准确性。研究结果表明:一次风率是影响预燃室环形回流区的关键因素,过低或过高的一次风速会分别对稳燃能力与降氮能力产生影响,在约8.8%的一次风率条件下能够保证有充足的回流量,有利于煤粉着火和排放控制;升高内二次风率能卷吸更多炉膛内高温烟气,有利于煤粉燃尽,但炉膛内部高温氧化性气氛区域增加,会导致污染物排放有所升高,约为43.5%的内二次风率能兼顾稳燃与降氮效果;采取适当比率的SOFA替代外二次风,能使得燃烧区域的含氮化合物更易被还原,从而降低排放,在23%SOFA风率下出现明显的低氮效果,NO_(x)排放为72 mg/m^(3)(6%O_(2)),与0%SOFA风率相比减排约67%。

氢燃料的制储运及其在燃气轮机中的应用

氢燃料具有来源广泛、燃烧无碳排放等优点,燃气轮机作为工业、电力等领域不可或缺的设备,将氢燃料用于燃气轮机可有效降低碳排放并解决可再生能源发电的波动问题。为向我国节能减排提供技术参考,本文围绕氢燃料的制、储、运以及在燃气轮机中的应用这四个环节进行综述,对比总结了各环节技术原理及优缺点。灰氢虽制备技术成熟、成本较低,但碳排放最高,随着CCUS(碳捕集、利用与封存)技术及绿氢制备技术的发展,蓝氢、绿氢将逐步取代灰氢。高压气态储氢、低温液态储氢是目前最成熟的储氢方式,储氢密度较高的固态、液态储氢是未来储氢技术发展的主流,但其目前存在的主要挑战为储氢材料吸放氢条件苛刻,需研制高效催化剂。液态船舶及管道掺氢运输是前景较好的输氢方式。氢燃气轮机分为掺氢、纯氢燃气轮机,目前示范项目基本为掺氢燃气轮机,扩散型掺氢燃烧器可燃烧掺氢比例高达90%的燃料,预混型掺氢燃烧器掺氢比例较低,纯氢燃烧器大多还处于试验阶段,但从长期来看,纯氢燃烧器是未来氢燃气轮机发展的主要方向。