基于火焰稳定特性浸没燃烧器的设计与试验研究

采用传统设计方法对浸没燃烧技术中的燃烧器进行设计,在实际应用过程中总出现回火、脱火、燃烧不稳定问题,本文根据火焰稳定特性知识构建了天然气火焰稳定性图,提供了一种对于燃烧气体燃料浸没燃烧器燃烧室的设计思路,并对该思路下设计的浸没燃烧器燃烧室进行了具体设计;融入旋流稳焰原理,一次空气与燃料旋流预混,二次空气冷却燃烧室外壁并被预热然后在燃烧室头部进入燃烧室助燃,进行了浸没燃烧器的总体设计,并对设计的燃烧器在自行设计的增压浸没燃烧试验台进行了初步试验研究,试验侧重燃烧稳定性与污染物排放。结果表明该浸没燃烧器燃烧稳定性相对较好,且由于良好的结构设计,节能减排效果显著。     

蓄热燃烧技术在石油化工管式炉应用的前景分析

石油化工管式加热炉与冶金行业的加热炉共同的地方,是有一个由耐火材料包同的燃烧室,在其底部或侧面设有燃烧器,不同之处是在石油化工管式炉内布置的是传热管.利用燃料燃烧产生的热量将流经管内的工艺介质加热到所需的温度.     

DZL1.4-0.7/95/70-AⅡ热水锅炉技改实践

工业锅炉是一种重要的热能动力设备,根据其燃烧特点以一台1.4MW热水锅炉作为研究对象,利用七孔探针测试了不同工况的燃烧室内部空气动力场,测试结果表明炉内燃烧室结构对炉内燃料燃烧、消烟除尘有较大影响.根据测试结果对燃烧室进行了技术改造,改造后炉内燃料的燃烧状况和消烟除尘效果有较大改善,有利于节能、环保.     

赛科裂解炉辐射段燃烧的数值模拟及优化

利用计算流体软件,采用合适的数学模型,对赛科（SECCO）裂解炉的两种设计方案进行数值模拟,得到裂解炉炉膛内流体流场、燃料燃烧和烟气温度场等详细信息,揭示了炉膛内烟气流动、燃烧和传热过程的相互影响及特点。模拟结果表明,底部燃烧器的原始设计方案中,热量分布不均,局部高温区,炉膛内温度梯度大;底部燃烧器加侧壁燃烧器的优化方案中,能提供较均匀的热量分布,炉膛内温度梯度小,有利于反应管均匀受热。     

原料与熔制

向燃烧室喷入燃料和鼓入空气,空气沿燃烧室内壁流动,燃料在燃烧室内燃烧后,加入玻璃配合料,它被加热和熔化。随后,熔化的玻璃配合料和燃烧产物沿斜管往下流动,燃烧产物由装在斜管底部     

煤层气燃烧器流动及NO_x生成特性数值研究

针对煤层气热值低的特点,设计了一台煤层气旋流燃烧器,采用数值模拟方法研究了不同热负荷及过量空气系数对燃烧性能的影响,并计算了燃烧污染物的生成.结果表明,在燃烧区域存在逆压梯度,加强了烟气的扰动,有利于形成稳定的高温区,提高燃烧效率.燃烧器负荷调节范围大,低负荷时仍能保持较高的燃烧温度和燃烧效率.过量空气系数为1.05时燃烧温度最高,此时NOx生成最多,仅为25.1 mg/m3.     

含不同粒度铝粉的铝/冰燃料的燃烧特性

用微米铝粉逐级取代部分纳米铝粉制备铝/冰燃料,采用表面接触法和高速摄影技术研究了不同粒度铝粉改善铝/冰燃料燃烧特性的效果. 结果表明,随微米铝粉取代量增加,铝/冰燃料燃烧反应速率和剧烈程度均先提高后降低,微米铝粉取代量为30%(w)时,铝/冰燃料最高升温速率达6062.24℃/s,是纯纳米铝/冰燃料的3.8倍. 用微米铝粉取代部分纳米铝粉均不同程度提高铝/冰燃料的燃面传播速率,微米铝粉取代量约为20%(w)时燃烧性能最佳,燃面传播速率较纯纳米铝/冰燃料提高57.8%. 在分析实验结果的基础上,建立了铝/冰燃料的燃烧火焰模型.     

新型低氮燃烧器在加热炉脱硝改造中的应用

抑制燃气燃烧装置产生的NO_x对保护大气环境是至关重要的一个方面。通过采用低NO_x的燃烧技术,改变燃烧条件抑制氮氧化物生成,从而降低NO_x的排放。影响燃烧过程中NO_x生成的主要因素是燃烧温度、烟气在高温区的停留时间、烟气中各种组分的浓度以及混合程度,对其进行了探讨。由于燃烧方法和燃烧条件对NO_x的生成有较大影响,因此可以通过改进燃烧技术来降低NO_x。选择新型低NO_x的燃烧器需考虑单台热负荷、燃料性质、空气供给量、温度、炉膛的高度,以及炉管与燃烧器的距离等影响因素,低氮燃烧器在加热炉脱硝改造中的应用取得了较好的效果。     

由煤的流化床气化生产发电用燃料气

英国国家煤炭局正在开发的一个联合循环发电过程包括:一个为煤料部分气化的流化床气化炉以及燃烧由气化所得半焦的第二个流化床——用热燃烧气稀释的洁净热燃料气在燃烧室燃烧,并进入燃气透平燃烧,燃气透平产生的动力推动空气压缩机和发电;废气通过一个热交换器,连同从燃烧器移出的热生产发电用蒸汽。用     

流化床内煤着火特性实验研究

为了对当前大量应用的带有床下启动燃烧器 CFB锅炉的启动运行提供指导 ,以及为从事循环流化床技术和煤燃烧理论研究提供参考 ,在电加热的小型流化床燃烧系统上 ,采用热烟气炉下点火的方式来研究煤粒在流化床内的燃烧特性 .测定了福建龙岩无烟煤的着火特性 ,分析了粒径、床温对着火点的影响 .并提出了煤颗粒在流化床内着火点测定的实验规范 .     

Estimation of the Maximum Efficiency of a Heat Recovery Burner

Estimates are obtained for the maximum efficiency of a system consisting of a heat recovery burner connected to an ideal Carnot heat engine. The burner serves as a heater of the ideal heat engine, and the cold side is at the ambient temperature. Combustion products heat the hot wall of the ideal engine and then transfer heat to the combustible mixture supplied to the combustion chamber. Recovery of the heat of the combustible mixture occurs through the heat-conducting wall of a countercurrent heat exchanger, in which the combustion products and the combustible mixture move toward each other in the channels connected by a heat-conducting partition. An estimate is obtained for the total efficiency of the system, which is defined as the ratio of the net power of the ideal engine to the chemical energy flux reaching the burner device. It is shown that the total efficiency of the system can approach the Carnot-cycle efficiency with the maximum possible temperature of the hot side of the ideal heat engine.     

Numerical simulation of the combustion of hydrogen-air mixture in micro-scaled chambers. Part I: Fundamental study

Understanding of micro-scale combustion mechanism is very essential to the development of combustion-based micro-power devices, which may supply much higher energy density than the batteries used nowadays. In part I of this paper, Computational Fluid Dynamics (CFD)-based numerical simulations have been performed to study the combustion of premixed hydrogen-air mixture in a series of chambers with same shape aspect ratio but various dimensions from millimetre to micron level. The transition of the combustion phenomena in the chambers from relatively large scale to micro-scale has been studied numerically to investigate the micro-combustion mechanism. The combustion model of premixed hydrogen-air mixture represents the detailed reaction mechanism with 19 reversible elementary reactions and nine species. The effect of various heat transfer conditions at chamber wall, e.g. adiabatic wall, with heat loss and heat conduction within the wall, on the combustion is analysed. These thermal conditions have strong effects on the combustion especially when the chamber dimension goes smaller and the ratio of surface area to volume becomes larger. Both factors, such as larger heat loss through the chamber wall and smaller chamber dimension size, may lead to the thermal quenching of micro-scale combustion. The simulation results also indicate that the stable combustion in a micro-scaled chamber may be sustained through increasing the ratio of flow residence time in chamber to chemical reaction time, and maintaining proper thermal condition. In part II of this paper, the numerical modelling method developed here is applied to analyse the micro-combustion characteristics in a three-dimensional micro-combustor based on the prototype developed by the MIT group for a micro gas turbine engine.     

Premixed gas combustion stabilized in fiber felt and its application to a novel radiant burner

Premixed gas combustion stabilized in a unique ceramic fiber felt has been investigated. Our aim was to better understand the flame structure and flame stabilization mechanisms in the porous felt medium in order to develop a new radiant burner. A novel recuperative radiant burner was designed and constructed. A flame stabilizes near the downstream interface of the porous medium that is an excellent selective thermal emitter. The burner was developed for use as a gas-fired light source. The combustion performance of the burner at various operating conditions and the effect of heat recuperation are presented. Combustion modes on the fiber felt were examined carefully. An optimal flame structure for the premixed gas combustion is attained and the flame stabilizes in the porous fiber felt at radiant mode combustion over a wide range of firing rates. The burner emits desired spectral radiation and generates fairly intense light at the conditions of heat recuperation. The light radiant burner could be used as an alternative low-glare light source in an integrated heat and light system in which the light is distributed through light pipes.     

Pore-level numerical simulation of methane-air combustion in a simplified two-layer porous burner

A simplified two-dimensional model of two-layer porous burner based on pore level is developed.The heat transfer of solid phase in porous burner is seen as the synergistic effects of conduction through con-necting bridges and surface radiation between the solid particles in the model.A numerical simulation study on the characteristics of flow,combustion and heat transfer in the two-layer porous burner is car-ried out using the pore level model,and the effects of the control parameters such as the inlet velocity and solid thermal conductivity on thermal non-equilibrium are investigated.The results show that the flame structure is highly two-dimensional based on pore level.Obvious thermal non-equilibrium in the burner for the two phases and solid phase are observed,the largest temperature difference between the gas and solid phases is observed in combustion zone,while the temperature difference inside the solid particles is largest near the flame front.The results also reveal that thermal non-equilibrium of por-ous burner is much affected by the inlet velocity and solid thermal conductivity.     

Start‐Up of HT‐PEFC Systems Operating with Diesel and Kerosene for APU Applications

Fuel‐cell‐based auxiliary power units offer power generation with reduced fuel consumption and low emissions. A very promising system is the combination of an autothermal reformer with a high‐temperature polymer electrolyte fuel cell. A fast start‐up procedure is a crucial requirement for the use of this system as an auxiliary power unit. This paper reports on the development of a suitable start‐up strategy for a 10 kW_el auxiliary power unit with a start‐up burner. A commercially available diesel burner was tested as a start‐up device. A dynamic MATLAB/Simulink model was developed to analyze different start‐up strategies. With the currently available apparatus and start‐up burner it takes 2,260 s before power generation can begin according to simulation results. The fuel processor alone would be ready for operation after 1,000 s. An optimization of the fuel cell stack with regard to its thermal mass would lead to a start‐up time of 720 s. A reduction to 600 s is possible with a slight customization of the start‐up burner.     

新型低氮燃气分级燃烧器燃烧特性和NOx排放的CFD研究

应用CFD软件Fluent数值模拟了某二甲苯塔再沸炉在役油气联合燃烧器燃烧和NOx排放特性,分析了其NOx排放浓度较高的原因,提出了新型低NOx燃气分级燃烧器的改造方案,并数值模拟了新型燃烧器空气预热温度Tair、过剩空气系数α和主辅喷枪燃气质量分率Rp对辐射室壁面热通量、出口温度、火焰高度和炉膛出口NOx排放浓度的影响。针对在役燃烧器的模拟结果与现场运行数据吻合良好,说明所选模型能够正确模拟炉膛内部的流动、辐射、燃烧和NOx生成过程。新型燃烧器模拟结果表明,增加Tair会增加辐射壁面热通量,同时也会增加NO的排放;辐射壁面热通量随α增加而降低,NOx排放浓度随α增加而增加;Rp对炉内传热和NOx排放的影响并不明显。当Tair = 220℃、α = 1.05及Rp= 0.24时,新型燃烧器在模拟范围内达到最佳运行工况,辐射壁热通量为37.45kW/m2,NOx排放浓度为12.1μL/L。     

Entrainment effects on combustion and emission characteristics of turbulent non-premixed ammonia/air and methane/air swirl flames through a developed perforated burner

A fuel/oxidizer mixture can be burned using a colourless distributed combustion (CDC) process to obtain low emissions and homogeneous combustion. As an alternative way, a perforated burner can be designed to achieve homogeneous combustion and low emissions without changing the combustion performance by having entrainment effects on the combustion chamber. In this study, computational fluid dynamics (CFD) 3D modelling was performed in a perforated burner for ammonia/methane fuels in order to obtain the distributed regime and focus on the entrainment effects. In numerical analysis, the eddy break-up was used as combustion model, k-Ɛ as turbulence model, and P-1 as radiation model. In this study, 10% and 20% entrainment rates were provided from the flame holder wall of the perforated burner. The effects of entrainment rates on temperature, velocity, and NO_X emission values were examined. According to the results, when the entrainment rate was increased from 10% to 20%, the overall temperature values of ammonia and methane combustion slightly increased by approximately 1.0%, while on the other hand the maximum temperature levels in the near burner zone decreased by about 5.0%. The findings demonstrated that temperature and velocity distributions got more uniform and the flame zones became thinner. This provided a more colourless and invisible flame appearance. In this way, an improvement in the thermal field has been achieved. In conclusion, when the effect of the distributed regime on NO_X emission levels was examined, it has been noted that entrainment effects enable the achievement of low emission levels (approximately 9.0%).     

预燃室对逆喷旋流煤粉燃烧器流场特性作用研究

煤粉高效低氮燃烧技术是煤炭高效利用领域持续关注的热点。煤粉燃烧器作为煤粉锅炉的核心设备,研究适合多煤种、宽负荷条件的煤粉燃烧器设计原理及技术至关重要。逆喷射流稳燃机理大都应用在航空发动机和燃气轮机领域,在煤粉燃烧领域应用极少。前人大量研究了预燃室对旋流燃烧器流场特性的影响,但鲜见预燃室对逆喷旋流燃烧器流场影响的相关研究。为了探究预燃室对逆喷旋流煤粉燃烧器流场特性的影响规律,笔者针对一款20 t/h逆喷旋流燃烧器,基于等温模化原理建立冷态燃烧器模型,利用热线风速仪和飘带法进行了流场测试和分析,结果表明:预燃室的存在不改变逆喷旋流煤粉燃烧器回流区环形的形状,但在逆喷旋流煤粉燃烧器内形成一个有利于煤粉着火的轴向速度低和湍流强度大的回流区。在X/D<1.3区域内,由于圆锥形预燃室对气流的挤压作用,预燃室的存在对回流区的面积起到抑制作用;在1.32.3区域内,预燃室对燃烧器内部流场的作用减弱,可忽略不计。在预燃室的作用下,回流区最宽处的直径从0.97D降至0.86D,最大相对回流率位置从截面X/D=1后移到截面X/D=1.6处,相对回流率从1.17减小至0.99。预燃室的存在对二次风区域内的轴向平均速度和湍流度分布规律影响较大。无预燃室工况下,在X/D<0.6区域内,速度和湍流度均出现峰值,在X/D>1.6区域内峰值消失,内外二次风完全混合;有预燃室工况下,在X/D<0.6区域速度沿着径向方向逐渐增大,湍流度沿着径向方向逐渐减小,在X/D>1.6区域,速度和湍流度沿着径向方向分布均匀。预燃室的存在有利于回流区煤粉的稳定燃烧,工程应用中起到煤粉迅速着火以及难燃煤稳定燃烧的作用。另外预燃室壁面气流速度较大,刚性强,避免预燃室壁面超温或结焦现象的发生,延长了煤粉燃烧器无故障运行时间和整体的使用寿命。     

Tandem换热式转化装置开工烧嘴的操作

介绍换热式转化装置开工烧嘴的点火及开车过程,以及开工烧嘴的操作与运行条件及注意事项.