一种窑炉燃烧器的改型实践

一、前言燃烧室的性能与燃油雾化质量,以及燃油和空气的混合状况密切相关。为了稳定火焰,设计时还应采取措施建立起局部回流区,以形成“自动点火源”。某厂从日本引进的陶瓷隧道窑,采用了直流突扩燃烧器见图1,以柴油为燃料。燃油喷口处的二次风通道直径为55mm,直流式燃油喷嘴,并以弱旋一次风气动雾化。这种设计方案结构简单,利用烧嘴砖周边的突扩回流区建立起自动点火源,借此稳定火焰。实践表明,以柴油当燃料时,可以维持稳定的燃烧,但不适     

水平螺旋槽管油膜燃烧的实验研究

柴油水平螺旋槽管降膜蒸发机理可实现柴油的快速均匀蒸发,应用于燃烧室中可实现燃料与空气的迅速良好混合,有利于提高燃烧室燃烧效率并有效降低污染物排放。实验样机已实现工作过程的自动控制,体现出了优良的性能,与传统的基于转杯雾化机理燃烧室作了对比实验。并对实验结果进行了理论分析。研究结果表明,由于具有更均匀的混合气形成,柴油水平螺旋槽管降膜燃烧比传统燃烧方式具有更高的燃烧效率和更低的CO和NOx排放量。     

基于两种不同原理燃烧室的独立式供暖系统对比实验研究

柴油水平螺旋槽管降膜蒸发可实现柴油的快速均匀蒸发,应用于燃烧室中可实现燃料与空气的迅速良好混合,有利于提高燃烧器燃烧效率并有效降低污染物排放.进行了降膜燃烧器与传统的转杯雾化燃烧器在车用独立式供暖系统中的对比实验.实验结果表明,由于良好的混合气形成,降膜雾化燃烧器具有更高的整机效率和较低的污染指标.     

柴油机燃油供给系统

1.柴油机燃油供给系统的功用和组成 1.功用柴油机燃油供给系统的功用是根据柴油机的工作要求,定时、定量、定压地将雾化质量良好的清洁柴油按一定的喷油规律喷入气缸内,并使其与燃烧室内的空气迅速而良好地混合和燃烧。它的工作好坏直接影响到混合气的质量。因此,柴油机的功率、经济性以及工作可     

柴油机排放控制的进展(下)

<正> 3.2 燃烧系统通常,燃烧系统包括进气道和喷油系统的元件。不过,就本文而言,燃烧系统指的是气缸内燃油和空气混合并燃烧的区域。与排放减少有关的三个方面是燃烧室形状、燃烧室位置和压缩比。 3.2.1 燃烧室形状在燃烧开始前实现燃油和空气良好混合     

一种窑炉燃烧器的改型实践

燃烧室的工作与燃油雾化质量以及燃油和空气的混合状况密切相关。为了稳定火焰,设计时还应采取措施建立起局部回流区,以形成“自动点火源”。某厂从日本引进的陶瓷隧道窑,采用了直流突扩燃烧器(见图1),以柴油为燃料。燃油喷口处的二次风通道直径为55mm,直流式燃油喷嘴,并以弱旅一次风气动雾化。这种设计方案结构简单,利用烧嘴砖周边的突扩回流区建立起自动点火源,借此稳定火焰。实践表     

某型燃气轮机燃烧室燃烧流场数值研究

燃气轮机燃烧室的燃烧特性受到旋流强度、雾化特性等因素的强烈影响,旋流强度和雾化特性分析对燃烧室的设计和优化具有非常重要的作用。对燃气轮机燃烧室的燃烧流场,应用商用程序FLUENT进行了数值模拟,并分析了空气过量系数α和燃油雾化粒径对燃烧室内燃烧特性的影响。模拟结果表明,控制空气过量系数和燃油雾化粒径对提高燃烧室工作性能和降低污染物排放具有重要意义。     

分室式燃烧炉的烘炉

分室式燃烧炉概况 我所为某厂设计生产的一座燃油分室式燃烧炉,中间用粘土砖墙隔开,构成2个燃烧室,每个燃烧室有2个F-100型低压油烧嘴,并且每个燃烧室有独立的燃烧系统。燃料为60重油,燃烧室最高工作温度为1250℃,重油在燃烧室内充分雾化燃烧,同时在燃烧室末端向燃烧室中掺入170～180℃热风,以便降低进人烟道的烟气的温度。高温烟气通过烟道中金属片状换热器预热空气,被预热的空气用高温循环风机吹入干燥炉,干燥物料。最后的废气由烟囱排出。 分室式燃烧炉平面结构图如图1所示。     

柴油机基本知识讲座(四)

<正> 4 柴油机混合气形成和燃烧在柴油机工作循环的压缩行程后期,当活塞行将达到上止点时,柴油开始喷入气缸。这时在高压下喷射出来的燃油油束与气缸内的空气相碰撞而分散和雾化。燃油油滴被高温空气加强蒸发形成油气。油气与空气相混合,当达到一定的混合比例并且温度要在600℃以上时,就自行发生稳定的燃烧。这样一个从燃油喷射到完成燃烧的全过程叫做混合气形成和燃烧     

WZ003039燃烧室内燃料着火浓度界限区的研究——《тегчоэнергетика》

对燃料与空气混合物的着火浓度界限区和着火过程进行了数学描述和计算，对燃烧反应物和燃烧室结构参数的影响进行了研究。根据计算和测量结果做出了各因素影响的曲线图。从中可以看出，提高空气的温度和压力、增加燃烧室的直径，可增大界限区；增加雾化颗粒直径和单位面积上烧嘴的数目，会使着火浓度界限区变小。图7参7     

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的燃烧性能进行了评价,考察了不同进口速度u₀、当量比Φ和多孔介质导热系数对氨/空气火焰特性和NO排放的影响。结果表明,多孔介质燃烧器能在u₀ = 3 ~ 7 m/s和Φ = 0.9 ~ 1.2条件下稳定燃烧;随着多孔介质导热系数的增大,火焰最高温度下降且火焰位置向上游移动;减小进口速度和增大当量比能够显著降低NO的排放。     

Mechanism analysis on the pulverized coal combustion flame stability and NOx emission in a swirl burner with deep air staging

Low NOx burner and air staged combustion are widely applied to control NOx emission in coal-fired power plants. The gas-solid two-phase flow, pulverized coal combustion and NOx emission characteristics of a single low NOx swirl burner in an existing coal-fired boiler was numerically simulated to analyze the mechanisms of flame stability and in-flame NOx reduction. And the detailed NOx formation and reduction model under fuel rich conditions was employed to optimize NOx emissions for the low NOx burner with air staged combustion of different burner stoichiometric ratios. The results show that the specially-designed swirl burner structures including the pulverized coal concentrator, flame stabilizing ring and baffle plate create an ignition region of high gas temperature, proper oxygen concentration and high pulverized coal concentration near the annular recirculation zone at the burner outlet for flame stability. At the same time, the annular recirculation zone is generated between the primary and secondary air jets to promote the rapid ignition and combustion of pulverized coal particles to consume oxygen, and then a reducing region is formed as fuel-rich environment to contribute to in-flame NO_X reduction. Moreover, the NOx concentration at the outlet of the combustion chamber is greatly reduced when the deep air staged combustion with the burner stoichiometric ratio of 0.75 is adopted, and the CO concentration at the outlet of the combustion chamber can be maintained simultaneously at a low level through the over-fired air injection of high velocity to enhance the mixing of the fresh air with the flue gas, which can provide the optimal solution for lower NOx emission in the existing coal-fired boilers.     

喷射式燃烧器气体流动与燃烧数值模拟

对一国产30kW车用喷射式加热器的燃烧器内气体流动与燃烧进行了数值模拟。由计算分析知．燃烧器导流体切向进气道所进空气射流可加强混合气的混合燃烧,并在导流体底部形成一绕中心轴线的涡流环,因该涡流环中心存在低压,从而可使部分下游燃烧的高温气体在燃烧室尾部缩口的配合下向中上游回流。该回流在燃烧室中下游产生一个绕燃烧室中心轴线的回流环,该回流环既可使高温回流气体维持燃烧器的续燃温度．同时还可加速混合气的燃烧。但从燃烧室的温度场分布图看,其高温区有所偏后,这对燃烧室在不同空燃比下的续燃稳定性不利．且易造成排气温度过高,使热效率下降．因此燃烧室缩口须适当前调．以使回流区前移。     

Experimental study of the fuel jet combustion in high temperature and low oxygen content exhaust gases

The performance of high temperature air combustion (HiTAC) depends on the heat regenerator efficiency and on the way fuel is mixed with furnace gases. In this work, combustion of a single fuel jet of gasol (>95% of propane) was investigated experimentally. Experiments were carried out in steady-state conditions using a single jet flame furnace. The jet of fuel was co-axially injected into high temperature exhaust gases generated by means of a gas burner also fired with gasol. Thus, instead of highly preheated and oxygen depleted air, which was normally used by other researches for such studies, this work has used high temperature and low oxygen content exhaust gases as the oxidiser. A water-cooled fuel nozzle was used to control fuel inlet temperature. Influence of the oxygen content in the oxidiser, at temperatures of 860–890 °C, on the flame visibility and the reactants composition was investigated. The combustion of gasol in hot flue gases appeared to be very stable and complete even at very low oxygen concentration. The oxygen concentration in the oxidiser was found to have a substantial effect on flame size, luminosity, colour, visibility and lift-off distance. Reduced oxygen concentration increases the flame size and lift-off distance, and decreases luminosity and visibility. The HiTAC flame first became bluish and then non-visible at sufficiently low concentration of oxygen in the oxidiser. In this work, results are presented for the constant ratio between fuel jet velocity and velocity of co-flowing flue gases. This ratio was equal to 26.     

单元熔窑燃烧过程数值模拟

对单元熔窑燃烧空间内的流动,燃烧及辐射传热等过程进行数值模拟研究,比较燃烧布置方式对火焰形状及传热过程中的影响,结果表明,对于所研究的宽度为3．2m的窑炉,燃烧器的布置应采用错排方式。     

Development of an experimental test rig for cogeneration based on a Stirling engine and a biofuel burner

A system consisting of a last-generation Stirling engine (SE) and a fuel burner for distributed power generation has been developed and experimentally investigated. The heat generated by the combustion of two liquid fuels, a standard Diesel fuel and a rapeseed oil, is used as a heat source for the SE, that converts part of the thermal energy into mechanical and then electric energy. The hot head of the SE is kept in direct contact with the flame generated by the burner. The burner operating parameters, designed for Diesel fuel, were changed to make it possible to burn vegetable oils, not suitable for internal combustion engines. The possibility of adopting different configurations of the combustion chamber was taken into account to increase the system efficiency. The preliminary configurations adopted allowed to operate this integrated system, obtaining an electric power up to 4.4 kW_el with a net efficiency of 11.6%.     

Performance simulation of a low‐swirl burner for a Stirling engine

A new type of gas burner for Stirling engine that can recover adequate heat from exhaust gas was designed based on the plate heat exchanger and low‐swirl combustion technology, which consists of three components: a cyclone, a burner, and a circular plate heat exchanger. The circular plate heat exchanger tightly wound around the combustion chamber plays a high efficiency of heat recovery role. In consideration of the radial symmetry of the burner, a three‐dimensional numerical simulation was carried out by Ansys15. The velocity distribution, temperature distribution, and pressure distribution of the combustion gas were presented respectively. Strong backflow that came from the exhaust gas around the root of the flame in the combustion chamber and a vortex below the inlet of the exhaust gas channel were found, which were beneficial for the combustion and improving the uniformity of temperature distribution. Combustion behaviors of the burner under standard operating conditions were obtained, the highest temperature was about 2200 K in burner and the exhaust gas entered the plate heat exchanger at the temperature of 1375 K and exited at 464 K, with the waste heat recovery efficiency over 65.8%. And, the air‐fuel ratio and combustion power had negligible effect on the waste heat recovery efficiency.     

A two-stage burner

This new design of burner achieves improved fuel combustion by combining (i) a primary diffusion-flame from a wick with (ii) a secondary premixed-flame. The latter occurs as a result of fuel being vaporized by radiant heat from the diffusion flame and that vapour being mixed by convection with air entrained through an orifice. The efficiency of the diffusion-flame combustion is improved because the entrained air is introduced near the centre of the annular flame, so increasing the air/flame interface available for combustion.     

甲烷/空气典型混合模式在约束空间内的燃烧特性研究

燃料质量浓度分布在一定程度上影响混合气体的燃烧效率,能使燃气充分混合的同轴射流、旋片同轴、轴切结合、切向旋流等典型混合模式在航空发动机、燃气轮机及火箭发动机等先进燃烧技术应用中较为常见。因此,设计了甲烷/空气部分预混的燃烧实验装置,较为系统地实验研究了旋流数和轴向流速对混合气体在约束空间燃烧室内燃烧特性的影响。结果表明：对于有中心射流的混合结构,燃气轴向流速较低时产生黄色火焰,增大轴向流速,黄色火焰转为蓝色湍流火焰,且温度分布趋于均匀;纯切向旋流燃烧器的掺混效果较好,受燃气轴向流速的影响小,火焰结构稳定,均为蓝色火焰,温度轴/径向分布均匀且趋势一致,同当量比下燃烧产物中的污染物体积分数最小。     

Development and characterization of a low-NOx partially premixed hydrogen burner using numerical simulation and flame diagnostics

The utilization of hydrogen as a fuel in free jet burners faces particular challenges due to its special combustion properties. The high laminar and turbulent flame velocities may lead to issues in flame stability and operational safety in premixed and partially premixed burners. Additionally, a high adiabatic combustion temperature favors the formation of thermal nitric oxides (NO). This study presents the development and optimization of a partially premixed hydrogen burner with low emissions of nitric oxides. The single-nozzle burner features a very short premixing duct and a simple geometric design. In a first development step, the design of the burner is optimized by numerical investigation (Star CCM+) of mixture formation, which is improved by geometric changes of the nozzle. The impact of geometric optimization and of humidification of the combustion air on NO_x emissions is then investigated experimentally. The hydrogen flame is detected with an infrared camera to evaluate the flame stability for different burner configurations. The improved mixture formation by geometric optimization avoids temperature peaks and leads to a noticeable reduction in NO_x emissions for equivalence ratios below 0.85. The experimental investigations also show that NO_x emissions decrease with increasing relative humidity of combustion air. This single-nozzle forms the basis for multi-nozzle burners, where the desired output power can flexibly be adjusted by the number of single nozzles.