超临界600 MW机组英巴W火焰炉偏斜气固两相流和不对称燃烧研究

针对国内引进的首台参数最高、单机容量最大的超临界600 MW机组英巴W火焰锅炉,借助1:40冷模试验台的变分级风率试验揭示其炉内气固两相流动特性,通过满负荷设计工况的工业测量获得炉内燃烧和NO_x排放特性。结果表明:不同分级风率下炉内均呈现"前长后短"型偏斜气固两相流场,后墙侧下行气固两相流较快倾向炉膛中心且较早上行,上行气流整体偏向前墙侧且后拱下部形成强回流区;下行气固两相流存在气固相滑移现象且前后墙侧差异大;后墙侧燃烧状况明显优于前墙侧,前墙侧严重低温和大量未燃尽颗粒物,导致锅炉整体燃尽效果差,飞灰可燃物高达8.5%;燃烧器区域一次风粉与二次风过早混合、炉内分级燃烧程度低和后墙侧局部高温环境的综合作用,导致NO_x排放质量浓度高达1 467 mg/m~3(φ(O_2)=6%)。建议改进炉膛结构、配风和燃烧系统,避免采用一、二次风密集相间的喷口布置方式,在构建对称燃烧流场、维持足够燃尽的同时,尽量加大炉内分级燃烧。     

改变燃尽风风量配比对660MW超超临界前后对冲煤粉锅炉炉内燃烧影响的数值模拟研究

利用ANSYS FLUENT14.0软件对某电厂660 MW超超临界旋流燃烧煤粉锅炉变燃尽风风量对NOx生成规律的影响进行数值模拟研究,数值模拟的结果与现场实际情况吻合比较好,验证了数值模拟结果的有效性,主要结论如下:总二次风量不变,改变燃尽风风量对炉内温度场分布的影响较大,对炉膛出口烟温影响较小;改变燃尽风风量对炉内NOx浓度影响较大;随着燃尽风风量的增加,炉膛出口CO的平均体积分数逐渐增加,炉内燃烧化学不完全热损失逐渐增大,锅炉热效率降低;在综合考虑锅炉的安全性、热效率和NOx排放量3个因素时,燃尽风风量的比例应该控制在23%～30%内。     

双级燃尽风在墙式燃烧锅炉上的应用

常规墙式燃烧锅炉单层燃尽风布置方式存在燃尽风对整个炉膛横断面的覆盖度较低,燃尽风与烟气混合程度较弱,NOx排放浓度较高的缺陷.为此,以国电蚌埠发电有限公司(蚌埠电厂)一期超临界2×600 MW机组锅炉为例进行燃烧方式改造.结果表明,设置双级燃尽风不仅能够增大燃尽风总量,而且使锅炉NOx排放浓度降低20％左右.同时,由于2层燃尽风喷口错列布置,扩大了气流对炉膛断面的覆盖范围,增强了燃尽风与炉内烟气的混合强度,使未燃尽物在有限的高度内充分燃烧,提高了锅炉燃烧效率.     

六角切圆锅炉低氮燃烧器改造前后燃烧特性的数值研究

为了研究褐煤燃烧六角切圆锅炉的燃烧稳定性问题,采用数值模拟技术对六角切圆锅炉低氮燃烧器改造前后的燃烧特性进行了计算,分析了改造前后炉内温度场、CO浓度以及燃尽风对整个炉内温度场的影响,并对燃烧器改造后炉内燃烧过程进行了试验。试验结果表明,低氮燃烧器改造后炉内温度场比改造前有了很大的改善,炉膛整个充满度较好,燃尽风的加入减少了炉膛出口飞灰可燃物,对煤粉的燃尽起了积极地作用,提高了燃烧效率和锅炉效率,但CO浓度有所增大。     

煤粉锅炉分级燃烧降低NOx排放的试验结果分析

通过对乌拉山电厂WGZ410/100-12型锅炉分级燃烧技术改造后的优化调整试验结果的分析,指明了燃尽风份额、二次风沿炉膛断面的分布、锅炉负荷、三次风投停等因素对炉内NO     

700MW锅炉炉内煤粉切圆燃烧过程的数值分析

综合考虑了煤粉燃烧过程涉及到的基本模型,对三菱公司生产的MB-FRR型锅炉(最大连续蒸发量为2 290t/h)的3种燃烧工况(100%、75%、50%)进行了数值模拟,并将模拟得到的炉膛内的速度场和温度场的分布与锅炉试验实测数据进行了分析比较.另外,重点对锅炉负荷降低后的炉内温度场变化进行分析,发现随着负荷的降低,在燃烬风喷射区域等温线会向炉膛中心轴线收缩,炉内的高温区域会有所缩小.提出了优化燃烧的方法,这对于切向燃烧锅炉的设计和运行具有一定的参考价值.     

低NOx燃烧技术在黄埔电厂5号炉上的应用

对1台300MW燃煤直流锅炉进行了分离布置燃尽风结合复合型燃烧系统的改造，炉内共布置了四层燃尽风，其中一层为紧靠型燃尽风，三层为可上下左右摆动的分离燃尽风，主燃区二次风喷口面积相应减小，并采用了一次风周界风与多燃烧切圆技术结合的复合型燃烧系统。锅炉改造后获得30～40％左右的NOx降低效果，且锅炉运行参数正常，炉内无结渣等现象，飞灰合碳量低，锅炉效率高。     

煤粉工业锅炉燃烧器和炉膛数值模拟与试验研究

针对煤粉工业锅炉,首先利用Fluent对燃烧器和炉膛进行数值模拟,分别研究变二次风旋流强度和锅炉负荷变化对燃烧特性的影响,结果显示:炉内煤粉燃烧温度随着二次风旋流强度的增大而升高,当二次风旋流强度为2.14时煤粉具有最高的燃尽率;锅炉负荷降至40%时燃烧器依然能维持煤粉在炉内的稳定燃烧,并保证煤粉的燃尽率达到较高水平。随后基于模拟结果,制造了4 t/h的煤粉工业锅炉样机,并对其进行了燃烧试验,结果表明煤粉在炉内能被较好地引燃并稳定燃烧,炉内温度分布较理想,锅炉平均效率达到88.75%,且尾部烟气中NOx、SO2及烟尘排放量均大大低于国家I类地区排放标准。     

墙式分离燃尽风对660MW切圆燃烧锅炉烟温偏差影响的数值模拟研究

为研究墙式分离燃尽风(separated over-fire air,SOFA)对切圆燃烧锅炉烟温偏差的影响效果,对1台660MW四角切圆燃烧锅炉开展了多工况炉内流动、燃烧和污染物排放数值模拟,研究了墙式SOFA风率和摆角对锅炉烟温偏差的影响。结果表明:SOFA风量增加,使得炉膛出口烟窗截面温度分布不均匀系数和炉膛出口截面烟温偏差减小,并且有利于降低NO_x排放量,但对煤粉燃尽率影响不大;SOFA喷口水平摆角增大,有利于降低锅炉烟温偏差;SOFA喷口向下摆动,有利于降低锅炉烟温偏差。     

细颗粒无烟煤焦在CFB锅炉燃烧室内的燃尽特性研究

建立细颗粒无烟煤焦在CFB燃烧室的燃烧模型。模型考虑颗粒与烟气的能量交换、炉内的流体动力特性、炉膛中氧气浓度分布、分离器的分离特性和颗粒在炉内停留时间等因素的影响,能较好描述细无烟煤焦的燃烧行为,反映出CFB锅炉飞灰碳在50μm粒径档附近处出现峰值分布的特征,与工业实际运行结果吻合良好。模型求解结果表明:提高燃烧温度对于福建无烟煤细颗粒的燃尽有利,但当温度高于1000℃时,进一步提高燃烧温度对降低飞灰含碳意义不大。另外,提高过量空气系数、降低炉膛烟气流速、提高锅炉分离器分离效率等有利于细无烟煤焦的燃尽。     

Studying the Aerodynamics of the TPP-210A Boiler Furnace When It Is Shifted to Operate with Dry-Ash Removal and Vortex Fuel Combustion

To reduce the amount of nitrogen oxide emissions and achieve more reliable operation of the TPP-210A boiler, a process arrangement for firing Grade TR Kuznetsk coal that involves using straight-flow burners and shifting the boiler from slag-tap to dry-ash removal is developed. Owing to a large burner downward slope angle and special arrangement of burners and nozzles, four large vertical vortices rotating in opposite directions are produced in the furnace lower part, as a result of which the combustion products dwell for a longer period of time in the burning zone and more complete fuel combustion is achieved. For verifying the operability and efficiency of the proposed combustion arrangement, investigations on a boiler furnace physical model were carried out using a technique for visualizing fuel jets and secondary and tertiary overfire air jets. The fuel jet temperature boundaries in the course of jet propagation in the furnace model are also determined. The study results have shown that staged fuel combustion will be set up with using the proposed arrangement of burners and nozzles. In addition, large vertical vortices produced in the furnace lower part will help to achieve more efficient use of the dry bottom hopper heating surfaces, due to which lower coal combustion product temperature in the furnace upper part and smaller content of combustible products in fly ash will be obtained. Owing to low values of air excess factor at the pulverized coal burner outlet and gradual admission of air into the vortex zone through a few nozzles with intense inner recirculation of combustion products to the jet initial section, staged combustion of pulverized coal and low nitrogen oxide emissions will be secured. Owing to expansion of fuel jets, a rapid growth of mass in the fuel jet is achieved, which is obtained both due to ejection of the jet itself and due to forced admission of hot fuel gases from other jets. Investigations carried out on the physical model have confirmed that the proposed combustion arrangement features high efficiency and that a low content of nitrogen oxides in flue gases is obtained.     

燃尽风与水平浓淡煤粉燃烧器联合应用对NOx生成特性影响

针对燃烧器采用四角切圆矩形炉膛布置方式的某燃用烟煤220 t/h锅炉，在主燃烧区域通过采用水平浓淡燃烧器、在三次风上层加装高位燃尽风喷口(SOFA)，采取燃料水平分级与空气垂直分级结合的方式进行改造，降低氮氧化物(NOx)排放水平。研究了SOFA对锅炉NOx排放和飞灰可燃物的影响规律。试验结果表明，当采用合理的燃尽风布置，煤粉由上层一次风喷口至OFA喷口间的流动时间保持在0.32 s左右时，采用合理的二次风配风调节方式，主燃烧器区域过量空气系数控制在0.85时，机组NOx排放量可降低到450 mg/m3以下。同时，对飞灰含碳量影响较小，保持在1.6%~2%之间，有效避免了过热器超温问题。     

锅炉风燃比在线自寻优控制方案设计

结合锅炉运行工况中热效率与空气系数的特定关系曲线,利用最优控制理论,引入步进搜索自寻优程序方案确立最佳风燃比,寻求不同负荷状态下的最佳风燃比,实现锅炉经济稳定燃烧,达到节约能源、环保运行的目的。     

高风温无焰燃烧锅炉特性与开发探讨

介绍一种基于高风温无焰燃烧原理的新型锅炉,探讨在炉膛内实现高风温无焰燃烧的途径及锅炉烧嘴的布置方式,分析锅炉特点和开发的技术路线。该种锅炉关键是应用一种基于分区燃烧和烟气再循环的蓄热式烧嘴。烧嘴蓄热体吸收具有炉膛温度的烟气显热,产生接近炉膛温度的高温空气。烧嘴中可集中或对称布置,设置炉外或炉墙内。保护具有高效节能、低NOx污染和结构紧凑等特点。     

Burning of solid biofuels in a cyclone-bed furnace chamber

Burning of solid biofuels (wood chips, milled peat, crushed peat bricks) in a cyclone-bed furnace of an air-heater boiler with power of 16.5 kW is investigated experimentally. It is established that the radial temperature distribution in a burning chamber is characterized by considerable nonisothermicity, which somewhat decreases as the amount of small fractions in the fuel increases. The influence of the air excess coefficient on the CO and NO concentrations in exhaust flue gases is shown. The dependence of the NO concentration on the air excess coefficient has the extremum in the studied range of experimental conditions. The comparison of established concentrations of CO and NO with regulations shows that when burning the wood fuel and peat brick according to the cyclone-bed technology, the air excess at the furnace output can be lowered to 1.07 (depending on the boiler aggregate power) simultaneously attaining the limiting CO concen tration, which makes it possible to increase the boiler efficiency compared with efficiency of boilers with bed furnaces (air excess coefficient of 1.3–1.6) by 2–4%.     

面向精密分析仪器的加热炉体温度场分布特征研究

热分析仪属于精密分析仪器,需要具有较高的测试分析性能要求,对热分析仪器炉体温度场分布特征的研究是实现其精密计量分析的必要前提条件。传统的炉体由于气流对温度分布的影响,容易产生测量误差。对炉体结构进行适当调整,可提高仪器的分析精度,改变其温漂特性。建立了炉体三维优化分布模型,应用有限元分析软件中的热分析模块对温度场进行分析。通过对热分析仪器的热力学分析、传热方式研究、不同进气流量下的炉腔温度场分析,阐述了热分析炉体温度场分布与气氛流量、炉体方向等之间的热传导关系。这一分析方法和理论结果可作为热分析仪器炉体温度场、炉内均温区分布情况的参考,为仪器的温度测量的可靠性、准确性、热分析仪的温度控制等研究提供依据。     

复杂煤质下锅炉燃烧精细化运行技术

混煤掺烧可有效降低火电厂燃料成本,但导致锅炉入炉煤煤质多变且偏离设计煤种。如何在复杂煤质下保障锅炉安全、经济、环保运行,是火电厂亟待解决的重要问题。分析了当前锅炉燃烧涉及的制粉、配风、设计制造等环节的主要瓶颈问题,提出了从燃料输入的优化、锅炉燃烧设备优化改造、燃烧精细运行控制三个方面紧密协同优化的整体解决方案。重点研究和探讨了实现煤粉侧精细控制、炉内精细配风的关键监测及优化运行技术及发展应用现状。锅炉燃烧优化是一个复杂的系统工程,给出的方案为火电厂实施燃烧优化工程提供了必要的设计指导和参考。     

Study of Sequential Two-Stage Combustion in a Low-Emission Gas Turbine Combustion Chamber

In this paper, we analyzed advanced ground-based power gas turbine units with low-emission combustion chambers used for consecutive two-stage fuel combustion. Such low-emission combustion chambers have a wide range of stable performance modes with reduced emission of harmful substances. The two-stage combustion chambers used in gas turbine units of various capacities—small (for example, M7A-03 with a capacity of approximately 8–10 MW), medium (L20A and L30A with a capacity of 18–30 MW) and large (9HA and GT36 with a capacity of over 300 MW)—showed their universality, efficiency, and good possibilities for scaling. The designs of low-emission combustion chambers for gas turbine units of different capacities are fundamentally similar. They consist of two sequentially located combustion volumes (stages), and each of them has its own burner unit. The first burner unit is typical for low-emission combustion chambers with the combustion of the premixed air-fuel mixture and consists of swirlers, mixing zone, fuel injectors, and igniters. The second burner unit is located downstream, and air-fuel mixtures of a different composition are supplied into it through special holes. The combustion of the mixtures occurs at a lower oxygen content and higher temperature. The ignition, work until idling, and loading before switching to the low-emission mode and switching to it are performed by the operation regulation of the first burner unit. Fuel in the second burner unit is supplied when a certain temperature of the gases arriving from the first combustion stage is achieved, which ensures its self-ignition. The further load is regulated by the fuel supply to the second burner unit. The design implementation of the sequential two-stage combustion scheme and approaches to regulating fuel and air distribution over the stages that ensures stable nonpulsating combustion are different and so they are of great scientific and practical interest.     

水煤浆再燃降低锅炉NOx排放的实验研究

为明确锅炉采用水煤浆再燃技术时的整体NOx控制效果和影响因素,利用神华煤,在0.25 MW沉降炉上,分别以煤粉和水煤浆为再燃燃料,进行了再燃NOx控制实验。结果显示,水煤浆再燃时的脱硝效果优于煤粉;一定范围内,较高的再燃比有利于锅炉整体再燃脱硝;锅炉主燃区宜采用氧化性氛围,此时该处的过量空气系数与脱硝效果呈现二次曲线关系;水煤浆再燃脱硝率与再燃区过量空气系数成反比。实验证实,水煤浆是一种较优的再燃燃料,可被广泛应用,以实现对工业炉NOx排放的有效控制。     

一种确定锅炉沿炉膛宽度方向热负荷分布的方法

电站锅炉在运行过程中,炉膛热负荷分布受燃料类型、燃烧方式、炉膛形状等多种因素的影响。针对炉膛热负荷分布难以准确预测的问题,提出了一种确定超超临界墙式切圆燃烧直流锅炉沿炉膛宽度方向热负荷分布的计算方法,将某一工况下管子出口温度作为已知条件,结合系统结构参数进行水动力计算,建立压降计算模型,研究水冷壁系统的流动特性以及炉膛的传热特性,确定水冷壁系统阻力、压降以及流量分布。根据计算结果得到单根水冷壁管沿炉膛宽度方向的热负荷分布规律,并以此为基础,建立热负荷模型,对另一工况进行计算与分析。计算结果表明,本文所提出的热负荷分布计算方法能够准确反映每根管子总吸热量沿炉膛宽度方向的分布,可以应用于锅炉现场运行的安全性分析。