Numerical Simulation on the Flow Field of a Four-channel Coal Burner

In this paper, the numerical simulation on the flow field of a four-channel coal burner was investigated with Fluent software. The three-dimension model was created with UG software. The structure was meshed by using Gambit software. The realizable K-ε turbulence model and simple method were adopted. The variation of the inner flow field of the burner was studied and analyzed. The results simulated to the burner by the realizable K-ε turbulence model show that the contours of theflowfield accord with the actual condition and the realizable K-ε model is proved to be feasible and the results of simulation are creditable. That will have important significance to the improvement of the structure and parameter optimization of the four-channel coal burner in the future.

Numerical Simulation of Oxy-coal Combustion for a Swirl Burner with EDC Model

The characteristics of oxy-coal combustion for a swirl burner with a specially designed preheating chamber are studied numerically. In order to increase the accuracy in the prediction of flame temperature and igni- tion position, eddy dissipation concept （EDC） model with a skeletal chemical reaction mechanism was adopted to describe the combustion of volatile matter. Simulation was conducted under six oxidant stream conditions with dif- ferent OjN2/CO2 molar ratios： 21/79/0, 30/70/0, 50/50/0, 21/0/79, 30/0/70 and 50/0/50. Results showed that 02 en- richment in the primary oxidant stream is in favor of combustion stabilization, acceleration of ignition and increase of maximum flame temperature, while the full substitution of N2 by CO2 in the oxidant stream delays ignition and decreases the maximum flame temperature. However, the overall flow field and flame shapes in these cases are very similar at the same flow rate of the primary oxidant stream. Combustion characteristics of the air-coal is similar to that of the oxy-coal with 30% 02 and 70% CO2 in the oxidant stream, indicating that the rear condition is suitable for retrofitting an air-coal fired boiler to an oxy-coal one. The swirl burner with a specially designed preheating chamber can increase flame temperature, accelerate ignition and enhance burning intensity of pulverized coal under oxy-coal combustion. Also, qualitative experimental validation indicated the burner can reduce the overall NOx emission under certain 02 enrichment and oxy-coal combustion conditions against the air-coal combustion.

CFD prediction of physical field for multi-air channel pulverized coal burner in rotary kiln

A 3-D numerical simulation with CFX software on physical field of multi-air channel coal burner in rotary kiln was carried out. The effects of various operational and structural parameters on flame feature and temperature distribution were investigated. A thermal measurement was conducted on a rotary kiln (4.5m in diameter, 90m in length) with four-air channel coal burner to determine the boundary conditions and to verify the simulation results. The calculation result shows that the distribution of velocity near burner exit is saddle-like; recirculation zones near nozzle and wall are useful for mixture primary air with coal and high temperature fume. A little central airflow can avoid coal backing up and cool nozzle. Adjusting the ratio of internal airflow to outer airflow is an effective and major means to regulate flame and temperature distribution in sintering region. Large whirlcone angle can intensify disturbution range at flame root to accelerate ignition and mixture. Large coal size can reduce high temperature region and result in coal combusting insufficiently. Too much combustion air will lengthen flame and increase heat loss.

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.

Research and Application of Internal Combustion Coal-Oxygen Burner for Fluxing in EAF

The investigation shows that using internal combustion coal-oxygen burner for the intensification of melting in EAF is feasible.Internal combustion coal-oxygen burner is better than external combustion coal-oxygen burner in the performance and energy saving of the process.Electrical consumption is decreased by 40 kW ? h/t,melting time is shortened by 18 min.The application of internal combustion coal-oxygen burner has a significant effect on decreasing EAF energy consumption.

耦合全炉膛的新型低NO_(x)旋流燃烧器性能

随着我国对氮氧化物(NO_(x))排放标准的不断收紧,电力行业迫切需要新的技术以减少NO_(x)排放。其中低NO_(x)旋流燃烧器技术作为控制NO_(x)排放的有效手段,受到广泛关注。针对一台600 MW对冲燃煤锅炉,设计并改进了一种新型低NO_(x)旋流燃烧器,研究了单只燃烧器流场、温度场及气体组分的分布特征,同时进一步分析了燃烧器耦合炉膛后的炉内温度场、NO分布情况。模拟结果表明:新型低NO_(x)旋流燃烧器中二次风为直流时煤粉燃烧较充分,且空气分级作用增强,可形成还原性气氛,NO排放量可进一步降低约21%。研究结果可为实际电站的低NO_(x)燃烧器改造提供理论依据和工程应用参考。

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。

基于孪生Inception网络的燃烧器火焰状态监测

燃煤电厂炉膛火焰的实时监测关系到发电经济性和锅炉的安全运行,而基于光能、热能和辐射能等能量信号的传统火检技术仅能探测火焰的有无,已无法满足日益迫切的火力发电精细化“调峰”需求。本文以实际电厂燃烧器火焰图像为研究对象,应用基于改进的Inception深度卷积神经网络(deep convolutional neural network,DCNN)的火焰状态分类方法,通过深入分析燃烧器火焰图像特点,对火焰多维度特征进行提取并制作数据集,同时将预处理后的不同类别火焰图像制作成火焰图像数据集,构建Inception DCNN,实现自动特征提取的火焰状态分类,并提出基于孪生Inception DCNN对燃烧器火焰状态进行分类。结果表明,改进的孪生Inception DCNN网络模型将火焰的状态分类问题转化为评价状态相似度问题,间接实现分类目标,识别准确率达到99.86%。

掺烧准东煤锅炉的结渣问题分析

某超临界燃煤锅炉掺烧准东系列煤,出现渣块掉落引起捞渣机过载跳闸。从煤质分析、落渣位置、炉膛吹灰试验、空气动力场、燃烧器喷口5个方面进行诊断分析,推断结渣和落渣原因,并停炉检查验证结论。结果表明,掺烧准东系列煤后,入炉煤具有中等结渣倾向,在燃烧器周界风口变形堵塞的诱导下,燃烧后的煤灰在侧边水冷壁结渣,渣块积聚后掉落引起捞渣机跳闸。结合掺烧准东系列煤的煤质特性,从运行和检修的角度提出防控措施,为相似情况的锅炉运行提供参考。

镍铁冶炼回转窑燃烧系统及窑内结圈的控制

对镍铁冶炼RKEF工艺所用回转窑燃烧系统进行全面对比分析,重点研究采用粉煤燃烧器焙烧的镍铁冶炼回转窑结圈的形成与预防控制措施,实现红土镍干矿在窑内充分还原、脱出结晶水的同时,控制窑皮厚度达到提高窑衬寿命的目的。

Review on research and development of oxy-coal burner for carbon capture

In the past two decades, the oxy-fuel combustion of pulverized coal has been extensively developed, leading to the completion of several large industrial pilot oxy-fuel plants worldwide. Various types of oxy-fuel burners have been designed and tested in largescale pilot plants as key components of oxy-fuel combustion. These burners face major challenges in terms of their flame stability because of their decreasing stream momentum ratio and increasing carbon dioxide concentration. However, it offers flexibility in adjusting the oxygen concentration in each burner stream. This study aims to provide a comprehensive review of the state-of-the-art knowledge on oxy-coal burner design and operation in power plants. First, the combustion characteristics under oxy-fuel conditions are briefly introduced. Subsequently, the principal requirements and fundamental parameters of the oxy-coal burners are discussed. The development process of oxy-fuel burners is also presented. Moreover, a compatible design strategy and scaling-up techniques are described for oxy-coal burners developed by the authors over the past ten years. The performances of oxy-coal burners in three large pilot oxy-fuel plants worldwide are summarized and compared. Finally, concluding remarks are provided and potential research needs are suggested.

Flame Morphology and Characteristic of Co-Firing Ammonia with Pulverized Coal on a Flat Flame Burner

Ammonia as a new green carbon free fuel co-combustion with coal can effectively reduce CO_(2)emission,but the research of flame morphology and characteristics of ammonia-coal co-combustion are not enough.In this work,we studied the co-combustion flame of NH_(3)and pulverized coal on flat flame burner under different oxygen mole fraction(X_(i,O_(2)))and NH_(3)co-firing energy ratios(E_(NH_(3))).We initially observed that the introduction of ammonia resulted in stratification within the ammonia-coal co-combustion flame,featuring a transparent flame at the root identified as the ammonia combustion zone.Due to challenges in visually observing the ignition of coal particles in the ammonia-coal co-combustion flame,we utilized Matlab software to analyze flame images across varying E_(NH_(3))and X_(i,O_(2)).The analysis indicates that,compared to pure coal combustion,the addition of ammonia advances the ignition delay time by 4.21 ms to 5.94 ms.As E_(NH_(3))increases,the ignition delay time initially decreases and then increases.Simultaneously,an increase in X_(i,O_(2))results in an earlier ignition delay time.The burn-off time and the flame divergence angle of pulverized coal demonstrated linear decreases and increases,respectively,with the growing ammonia ratio.The addition of ammonia facilitates the release of volatile matter from coal particles.However,in high-ammonia environments,oxygen consumption also impedes the surface reaction of coal particles.Finally,measurements of gas composition in the ammonia-coal flame flow field unveiled that the generated water-rich atmosphere intensified coal particle gasification,resulting in an elevated concentration of CO.Simultaneously,nitrogen-containing substances and coke produced during coal particle gasification underwent reduction reactions with NO_(x),leading to reduced NO_(x)emissions.

干煤粉气化炉主烧嘴与渣口匹配性研究

干煤粉气流床气化技术已经在国内外普遍推广应用,从干煤粉气化炉的组合烧嘴、下渣口及气化炉的结构和特点出发,讨论了干煤粉气化炉主烧嘴氧气旋流角度、主烧嘴煤粉通道半径及气化炉下渣口的尺寸等对气化效率的影响。结果发现,干煤粉气化炉选择氧气旋流角为25°、煤粉通道半径为92 mm的主烧嘴与下渣口直筒段内径为500 mm的渣口进行匹配,所产生的有效气含量最高,碳转化率最高,渣、饼残碳量最低,气化反应更充分,是一种较好的匹配选择。

水煤浆气化烧嘴喷口和炉砖烧蚀性的优化及应用

水煤浆加压气化工艺中工艺烧嘴的设计需与煤浆投料负荷相匹配。国内某公司6.5 MPa水煤浆加压气化装置原工艺烧嘴设计煤浆处理量73 m3/h,因下游合成气的需求变化使装置负荷需大幅改变,新方案烧嘴要求能满足75%~125%范围的负荷调节。为了评估极端负荷工况对气化装置造成的影响,针对该厂运行工况,对原烧嘴和新方案烧嘴进行了气化炉全炉燃烧数值模拟。计算结果表明:新方案优化了烧嘴在低负荷下的端面烧蚀和高负荷下的冲蚀问题,改善了高负荷下炉砖筒体和锥底的温度分布,有利于缓解炉砖的冲蚀速率。新方案实际投用后兼顾了较高的气化生产效率和宽广的负荷变化范围,验证了计算的正确性。

热动力站320t/h煤粉锅炉结焦问题的治理经验总结

针对某公司公用工程中心热动力站一期320 t/h煤粉锅炉在运行过程中出现的炉膛水冷壁和燃烧器大面积结焦问题,通过了解掌握使用煤种的特点、特性,校核炉膛主要热力特性参数,分析原燃烧器在设计、运行中存在的问题后,针对性地提出了采用降低燃烧区壁面热负荷、更换防结焦型低氮燃烧器及强化吹灰运行管理等全面系统的改造思路和方案。改造方案在停炉期间实施后,经过冷态空气动力场试验、热态调试及各种典型工况下的运行试验表明:改造后燃烧器着火及时、燃烧稳定,蒸汽参数合格,锅炉长周期运行出力得到大幅提高,燃烧器及炉膛壁面结焦问题得到了根本治理,氮氧化物初始排放浓度等各项运行经济指标均达到设计要求,为解决燃用低灰熔点榆林烟煤煤粉锅炉普遍存在的问题提供了一个成功治理的实例。

高压煤浆泵标定方法及注意事项

四喷嘴气化炉中的4个烧嘴独立运行,传统高压煤浆泵标定方法以泵为单位进行标定且误差较大,不能满足煤气化精细化运行的要求。本文以烧嘴为单位进行标定,并利用精确数据优化标定方法,提高煤浆泵标定的精确度。

贫煤锅炉全烧烟煤燃烧器改造技术研究

以某600 MW超临界前后对冲燃烧方式锅炉为研究对象,该锅炉煤种由贫煤更换为低灰熔点烟煤后存在炉膛结渣严重问题,分析发现燃烧系统改造时需考虑降低燃烧器区域热负荷,防止燃烧器区域温度过高引起炉膛发生严重结渣;为防止炉膛火焰中心上移,不能过多降低燃烧器区域热负荷,否则可能引起屏式过热器结渣、再热器超温、减温水量大、稳燃能力不足等问题。在改造方案中,将其上层燃烧器整体抬高2 500 mm,中层燃烧器整体抬高500 mm;改造后,中上层燃烧器的层间距为6 742 mm,中层与下层燃烧器层间距为5 242 mm。通过燃烧器不等间距布置,在THA工况下,可大幅降低燃烧器区域壁面热负荷至1.39 MW/m^(2);机组50%负荷及以上时,主汽温度达到571℃,再热汽温达到569℃,锅炉效率大于94%,炉膛出口烟气温度为1 000℃,高温再热器进口烟气温度为984℃,均低于燃用煤种灰熔点,可以较好地预防受热面结渣和燃烧器附近结渣。省煤器出口CO体积浓度最大为180μL/L,NOx质量浓度最大为235 mg/m^(3)(N),各项参数均满足改造目标要求。

直流煤粉燃烧器低负荷稳燃技术下的自动化控制策略分析与实践

随着能源需求的持续增长,环境污染和气候变化等问题日益凸显,促使能源领域寻求更高效、环保的解决方案。因此,深入探讨了直流煤粉燃烧器在低负荷燃烧技术方面的应用与优化,并分析其燃烧器工作原理。结果表明,通过采取一系列的自动化控制策略,并对其进行经济与环境效益评估,将能够提高能源转化效率、降低环境影响,为燃烧技术在现代化进程铺平一条清洁、高效的道路。

煤粉锅炉四角双切圆燃烧器的找正定位技术探究

四角切圆燃烧器安装找正定位的好与差,对炉膛煤粉燃烧和壁温偏差有直接的影响,从长期经济高效运行角度来看也有着重要的作用。以安装过的多台四角双切圆燃烧器的找正定位技术实践进行总结研究,从而实现更科学更符合设计要求的燃烧器安装。

煤粉锅炉燃烧系统灵活性改造调峰技术研究进展

随着清洁能源发电比重持续上升,煤电机组逐步转变成为基础调节电源,而锅炉作为煤电机组的三大主机之一,其为实现调峰速度和深度的关键设备。综述煤电灵活调峰政策及现状,系统分析锅炉侧提升灵活性的三大关键制约因素,即燃烧稳定性、水动力安全性和辅机适应性三者优化控制可满足宽负荷调节,在此基础上再分别从燃烧运行方式、燃烧器布置选型、智能检测与优化算法3个方面探讨提升燃烧稳定性的可行性路径及调峰技术措施,以期为实现电站锅炉灵活性调节提供基础理论支撑及技术借鉴。在燃烧运行方式方面,优化燃烧过程控制策略,合理调整燃烧空气量与燃料量的配比以及确保炉膛内温度稳定是提升燃烧性能的关键;在燃烧器布置选型方面,提高燃烧器的性能和适应性以达到锅炉负荷灵活变化的目的,同时选用合适的点火方式可以实现经济性和稳定性的目标。在智能检测与算法方面,实时监测锅炉运行参数,通过数据获取与分析实现自动调控及预警,从而实现燃烧过程的精确控制。