渐变型多孔介质中预混燃烧温度分布试验

进行了预混天然气在等孔隙率渐近变孔径的多孔介质中的燃烧试验，用热电偶测量了燃烧室温度分布，并与单一孔径（d=1mm）的均匀多孔介质中燃烧结果进行了比较。结果表明，渐变型多孔介质燃烧器比均匀型多孔介质燃烧器具有更多的优点：燃烧室温度分布更加均匀，燃烧更加稳定，并能更好的适应当量比和流量／功率的变化，由于孔径的变化，多孔介质中气流扰动增加，有利于火焰的稳定，当量比和流速变化范围增大。     

渐变型多孔介质燃气装置的试验研究

在一台0.8 t/h渐变型多孔介质燃气锅炉上进行了传热特性、污染物排放特性和阻力特性试验研究,结果表明,该多孔介质燃气炉具有体积小、负荷调节比大、换热效率高、污染物排放低和气流阻力小等特点.该燃气锅炉的特点是在燃烧室中设置有多孔介质与布置在其中的冷却介质管束,同样功率的多孔介质燃气炉体积只有常规自由火焰锅炉体积的1/5,换热效率大于90%,Nox排放质量浓度低于45 mg/m3,压降小于0.001 Mpa.     

惰性多孔介质中预混燃烧的研究进展

预混气体在惰性多孔介质中的燃烧具有燃烧速度快、燃烧效率高、温度分布均匀、贫燃极限宽、节约能源、污染物排放低等优点。介绍了惰性多孔介质中预混气体单向流动燃烧和往复流动燃烧的原理和特点,详述了火焰传播与驻定的机理,以及火焰传播中的不稳定现象,分析了影响火焰传播的因素,讨论了数值模拟中的物理模型、控制方程、边界条件、反应机理和求解方法,回顾了预混气体多孔介质燃烧技术的应用情况,分析指出了有待进一步研究的问题。     

基于多孔介质燃烧的端部辐射器的实验研究

设计了基于多孔介质燃烧技术的端部辐射器,研究不同预混气体流速(功率)下当量比对燃烧器燃烧稳定性、多孔介质内部温度、辐射器表面温度及其均匀性、污染物排放、辐射效率等特性的影响.结果表明,燃烧器辐射表面的温度均匀性较好.最大相对温差小于3%:多孔介质燃烧器可实现最低当量比0.33的稳定可持续燃烧;小功率燃烧时.多孔介质内部温度及端部辐射表面温度都随当量比增大而增加,且流量越大增加程度越大,可据此提出实现更高辐射表面温度的方案.实验工况范围内.最大辐射效率达23%;NO<,x>排放体积分数低于25×10<'6>,在当量比大于0.45时,CO排放体积分数均低于10×10<'6>.     

多孔泡沫陶瓷中预混火焰燃烧速率的试验研究

本文对在多孔泡沫陶瓷中的甲烷／空气预混燃烧的燃速特性进行了实验研究，用一专用燃烧器对两种材质不同孔径尺寸的多孔介质分别测定了它们的预混燃烧速率。所得结果表明，其燃速与层流无多孔介质的自由火焰相比有显著的提高，并且受到材质和孔径大小的影响。同时，当量皆可燃稳定上下界限也有相应扩大。     

多孔介质中预混火焰猝熄及自稳定性研究

分析了多孔介质中预混火焰的猝熄效应,试验测定了一系列工况下泡沫陶瓷的猝熄直径和自稳定范围,为多孔介质燃烧器的开发设计提供了依据。通过分析发现,猝熄直径受到多个参数的影响,包括：混合气体的流速u、预混气体的层流火焰传播速度SL、燃烧室空管Re、预混气体的导温系数a、当量比φ以及多孔介质固体温度Ts。通过对多孔介质中燃烧的自稳定性试验研究,发现了多孔介质燃烧器中火焰稳定极限(吹脱极限和回火极限)与多孔介质平均孔径和气流速度及燃烧当量比的关系。     

基于液体燃料的多孔介质燃烧技术研究现状

对国内外近年来关于多孔介质燃烧技术在液体燃料燃烧领域的实验及数值模拟研究做了较为全面的综述和分析。分析表明:多孔介质燃烧技术为液体燃料提供了一种可能的先进燃烧方式。相较于传统自由空间内的火焰燃烧,多孔介质燃烧技术可改善液体燃料的雾化、蒸发,获得低排放、高稳定性、宽负荷比的燃烧表现。该技术在燃油锅炉、燃气轮机、斯特林发动机等领域拥有广阔的应用前景。     

基于液体燃料的多孔介质燃烧技术研究现状

对国内外近年来关于多孔介质燃烧技术在液体燃料燃烧领域的实验及数值模拟研究做了较为全面的综述和分析。分析表明:多孔介质燃烧技术为液体燃料提供了一种可能的先进燃烧方式。相较于传统自由空间内的火焰燃烧,多孔介质燃烧技术可改善液体燃料的雾化、蒸发,获得低排放、高稳定性、宽负荷比的燃烧表现。该技术在燃油锅炉、燃气轮机、斯特林发动机等领域拥有广阔的应用前景。     

多孔介质内往复流动下超绝热燃烧的实验研究

对RSCP的燃烧特性进行了实验研究．建成了RSCP实验台，它由泡沫陶瓷燃烧器、电磁阀控制的周期换向进排气管路系统和测量系统组成．对各种工况参数(燃料空气当量比、气体流速、循环半周期)下多孔介质内轴向温度分布进行了系统的测量．实验结果表明，较之常规的自由火焰燃烧器，RSCP具有增强火焰稳定性、拓宽燃料可燃极限等优点．对丙烷-丁烷混合气，其贫可燃极限可扩展到当量比0．065．在实验基础上，探讨了RSCP实现超绝热燃烧的机理，总结出有关工况参数对其燃烧特性影响的规律．     

有序堆积床内预混气体燃烧特性实验研究

为研究预混气体在多孔介质燃烧器中的火焰燃烧特性,设计了一种新型多孔介质燃烧器,其中多孔介质区域由氧化铝圆柱体有序堆积而成.分别研究了当量比和入口速度对甲烷/空气预混气体在多孔介质燃烧器中的火焰温度分布、火焰最高温度以及火焰传播速度的影响.结果 表明:在当量比0.162～0.324、入口速度0.287～0.860 m/s...     

多孔燃烧器中氨/空气燃烧特性数值研究

氨具有氢密度高、生产成本低、基础设施完善等优点,作为一种潜在的可再生替代燃料受到了广泛的关注.目前,仅有少数研究关注氨气燃烧喷嘴的研究,针对氨气稳定燃烧喷嘴的研究尤其不足.为实现氨燃料的稳定燃烧和低污染物排放,本研究提出了一种氨用多孔介质燃烧器.对氨用多孔介质燃烧器建立了二维数值模型,并对预混氨/空气在多孔介质燃烧器中...     

Experimental study of the combustion of natural gas and high-hydrogen content syngases in a radiant porous media burner

The primary objective of this work is to study the blending of natural gas in equimolar proportions with three high hydrogen content syngases in a radiant porous media burner. We examined the effects of the composition of the syngases, the fuel-to-air ratio and the thermal input on the flame stability, the radiation efficiency and the pollutant emissions (CO and NOx). In this study, we emulated the syngases with H₂–CO mixtures, in which the H₂ to CO ratio was varied between 1.5 and 3. Additionally, pure natural gas was also used as a base fuel for comparison. The thermal inputs evaluated in this study correspond to two values (300 and 500 kW/m2) found in practical applications. The results indicate that the thermal input and the fuel-to-air ratio significantly influenced the temperature profile in the radiant porous media burner, the radiation efficiency, and the pollutant emissions. On the other hand, contrary to what was observed in other studies for lower hydrogen concentrations, we found that substituting natural gas with high hydrogen content syngases (up to 50%) affected the flame stability limits. Significant differences were also observed for the radiation efficiencies and pollutant emissions.     

天然气在渐变型多孔介质中的预混燃烧启动特性

针对天然气在渐变型多孔介质燃烧器中的点火启动过程进行了试验研究,通过监测燃烧器壁面或气体温度在点火后的变化,得到了影响启动时间的因素及特性,对特定的燃烧器而言,启动时间与预混气体当量比、流速以及点火位置有关,在冷态下点火,随着当量比接近理论当量比,启动时间减小;混合气体流速增大,启动时间增大;点火位置从燃烧器外移到燃烧器人口时,启动时间可大大缩小,采用小流速、近理论当量比条件下点火,对多孔介质层预热,有利于火焰迅速向上游移动,然后再调整到需求当量比或流速,可以大大减小燃烧器启动时间,采用孔径变化率高的渐变型多孔介质结构,也可以达到缩短启动时间的目的。     

多入口多孔介质燃烧器的数值模拟

在多入口燃烧器内加入多孔介质,以甲烷/空气为燃料,采用非预混燃烧的数值模拟方法,探究多入口燃烧器的燃烧情况.对比多孔介质燃烧与空间自由燃烧,分析了"超焓燃烧"现象;在多孔介质燃烧基础上,探究不同当量比对燃烧温度的影响;在多孔介质燃烧和不同当量比的基础上探究污染物CO和CO_2的排放情况.结果表明:多孔介质燃烧可以实现"超焓燃烧"特性,燃烧火焰温度高于自由空间燃烧温度;当量比对燃烧温度影响很大,随着当量比的增大,燃烧器内最高燃烧温度升高,但燃烧过程存在一个最佳当量比0.6,超过该当量比后最高温度将不再变化;多入口多孔介质燃烧有助于减少CO和CO_2的生成量.     

Fuel‐lean VOCs combustion in a porous burner stacked with alumina balls: A case for ethylene combustion

A porous burner stacked in turn with 3‐ and 9‐mm alumina pellets was established to perform C₂H₄ combustion experiments by acquiring the flammable limits, temperature variation characteristics, combustion wave velocity, pollutant emissions, and treatment efficiency. The burner operated well at equivalence ratios within 0.3 to 0.7. Larger alumina pellets widened the burner's lower flammable limit. As the flame propagated downstream, the higher premixed gas flow velocity and larger alumina pellets, the higher combustion wave velocity, whereas the circumstances were opposite as the flame spread upstream. The combustion temperature increased with the equivalence ratio and premixed gas flow velocity. In response to the effect of the alumina pellet dimension, 3‐mm alumina pellets corresponded to higher combustion temperatures, lower CO emissions, and higher treatment efficiency than those less than 9‐mm conditions.     

Experimental investigation of combustion in porous heating burners

The combustion characteristics of liquefied petroleum gas inside porous heating burners have been investigated experimentally under steady-state and transient conditions. Cooling tubes were embedded in the postflame region of the packed bed of a porous heating burner. The flame speed, temperature profile, and [NO_x] and [CO] in the product gases were monitored during an experiment. Due to the heat removal by the cooling tubes, a phenomenon termed metastable combustion was observed; this is that only one flame speed exists at a particular equivalence ratio for maintaining stable combustion within the porous bed of the porous heating burner. This behavior is quite different from that of porous burners without cooling tubes, in which an extended range of flame speeds usually is found for maintaining stable combustion. After metastable combustion has been established in a porous heating burner, a change in the equivalence ratio will stop the metastable combustion and drive the flame out of the packed bed. From the steady-state results, the porous heating burner was shown to maintain stable combustion under fuel-lean conditions with an equivalence ratio lower than the flammability limit of a normal free-burning system. The flame speed in a porous heating burner was found to decrease with an increase in the length of the porous bed. Combustion within a porous heating burner has the features of low flame temperature, extended reaction zone, high preheating temperature and low emissions of NO_x and CO. The flame temperature ranged from 1050 to 1250 °C, which is ∼200 °C lower than the adiabatic flame temperature at the corresponding equivalence ratio. The length of the reaction zone could be more than 70 mm and the preheating temperature ranged from 950 to 1000 °C. Both [NO_x] and [CO] were low, typically below 10 ppm.