废轮胎热解半焦的单颗粒燃烧特性实验研究

在单颗粒燃烧系统上研究了废旧轮胎热解半焦颗粒的燃烧特性，并探究了温度与颗粒粒径对燃烧的具体影响．结果表明，半焦颗粒在850℃及以下燃烧时经历挥发分析出及着火、挥发分燃烧、焦炭着火及焦炭燃烧4个阶段，在机理上属于典型的均质着火机理；在950℃以上时，焦炭着火早于挥发分着火，其着火机理转变为联合着火．此外，温度升高会缩短半焦颗粒着火时间等特征时间，而半焦颗粒粒径的增加则会增大挥发分火焰的体积并显著延迟焦炭的着火时间．研究结果为高效清洁利用轮胎衍生燃料提供了一定的基础研究数据．     

气化半焦加压着火特性及燃烧稳定性研究

在单炉膛双吊蓝加压热重分析仪上对气化半焦的加压着火特性和燃烧稳定性进行了较为系统的试验和理论研究,考察了半焦种类、总压、氧浓度、粒径和加热速率等因素对半焦着火特性和燃烧稳定性的影响规律。并以纯碳测试数据为基准,提出了燃烧稳定性的判别指数RW。研究表明,半焦的挥发份含量、固定碳含量以及孔结构是影响半焦着火温度的主要因素。随着总压和氧浓度的提高以厦粒径的减小,半焦的着火温度下降,燃烧稳定性提高;随着加热速率的增加,半焦的着火温度明显上升。     

半焦粒子团燃烧模型与计算分析

本文针对半焦粒子团燃烧现象，建立了球对称粒子团燃烧的准稳态模型，对粒子团的燃烧速率和粒子温度进行半分析、半数值求解，并具体针对由大径粒子（ａ＝１ｍｍ～６ｍｍ）和小径粒子（ａ＝３８μｍ～５０μｍ）所组成的粒子团的燃烧参数进行了计算，对计算结果进行了分析比较。     

多联产半焦燃烧特性的热重研究

利用热重分析仪对热-电-气-焦油多联产工艺中煤干馏半焦的燃烧特性进行了分析,采用可燃性指数Kr、燃烧特性指数S、燃烧稳定性指数Rw、燃尽特性指数Cb及样品反应活化能考察了干馏温度对半焦燃烧特性的影响.结果表明:随着干馏温度的升高,半焦的着火性能、燃烧稳定性及总体燃烧性能变差,燃尽性能变佳,燃烧活化能增加;半焦的燃烧反应可用一级反应来描述,4种半焦的活化能在88.72～112.83 kJ/mol范围内.     

煤部分气化后生成半焦的特性

对日照烟煤和京西无烟煤在不同温度下制得半焦进行了工业分析和硫的元素分析，研究了不同煤种制得半焦中挥发分、灰分、固定碳以及硫元素含量随制备温度不同的变化趋势，并在管式沉降炉中进行了半焦的燃烧实验，分别计算了不同半焦的燃烧动力学参数。     

甲烷火焰中氢气对着火与燃尽的影响

利用化学反应动力学机理研究了甲烷－空气预混火焰添加H2的着火和燃尽特性。通过分析计算,讨论了氢气对甲烷燃烧过程及着火温度、燃烧速率、燃尽时间的影响。结果表明,甲烷火焰中少量氢气的存在不仅可以降低甲烷的着火温度,而且可以显著增大燃烧速率,缩短燃尽时间,这些结果与已有的实验结果吻合。     

多联产半焦的加压着火及燃烧特性

在Cahn TherMax 500型加压热重仪上,对煤的热电气焦油多联产半焦的燃烧特性进行了系统研究,着重考察了压力对半焦热失重特性、着火特性、燃烧产物释放特性、燃烧稳定性、燃尽及综合燃烧特性的影响.试验结果表明,随着压力的升高,半焦燃烧特性明显提高.压力从常压升高到2.4,MPa,燃烧产物释放特性指数r从0.115提高到0.590,燃烧稳定性指数RW从10.7提高到33.2,着火温度从666,℃降低到523,℃,综合燃烧特性指数S从0.49提高到2.83.     

CeO2和MnO2协同催化半焦燃烧与脱硝的试验研究

采用向半焦中添加CeO2和MnO2两种催化剂的方法,通过热重分析(TGA)、扫描电子显微镜(SEM)和X射线光电子能谱(XPS)等技术,研究了添加剂种类及比例对催化半焦燃烧和脱硝的影响.结果 表明:当添加质量分数为5％的CeO2催化剂时半焦的着火温度和燃尽温度分别降低了1和11℃,当添加质量分数为5％的MnO2催化剂时...     

基于可视化温度场分析的柴油机缸内燃烧过程研究

在一台视窗上置式柴油机可视化实验装置上用高速摄像机记录下缸内燃烧过程的火焰照片,应用三基色法计算了缸内燃烧温度场.结果表明,用三基色法分析的缸内温度场分布与实际情况相一致；结合示功图曲线对柴油机着火和燃烧过程进行了分析,得到的结果符合柴油机实际着火和燃烧过程的发展规律.燃油在高温缺氧情况下会发生裂解形成较高温度的较大碳粒,影响相应零部件的使用寿命和发动机性能.     

含氧清洁燃料二甲醚燃烧特性的数学模拟

以含氧清洁燃料DME燃烧的化学反应机理为基础,建立了DME着火过程的数学模型,并且利用CHEMKIN计算程序软件包对其进行了自燃着火过程的模拟计算,预测结果与实验结果吻合较好,然后与以零维燃烧模型为基础的工作过程模拟相耦合,分析在柴油机上燃用DME的燃烧过程的特点。     

一种天然焦燃烧特性的试验研究

天然焦是煤接触岩浆岩受热分解后的固体残余物,它是岩浆岩侵入煤层或煤层附近,由煤层受热烘烤而干馏变成的．天然焦一般作为难以利用的能源考虑。为了开拓天然焦综合利用新途径,本文利用热重分析法对该天然焦、济宁煤及二者混合燃料的着火、燃尽等燃烧特性进行了实验研究。热重试验结果表明,天然焦的着火温度为876．3K,其着火温度最高,其次是混煤,济宁燃煤着火温度最低;但是天然焦的燃尽时间最短,济宁煤燃尽时间居中,混煤燃尽所需时间最长。综合试验研究及理论分析,天然焦混煤燃料可以作为电站锅炉燃料．本研究可为天然焦用作电厂燃料提供依据。     

Fast Ignition and Stable Combustion of Coarse Coal Particles in a Nonslagging Cyclone Combustor

A combustion set-up of an innovative nonalagging cyclone combustor called “Spouting-Cyclone Combustor(SCC)”，,with two-stage combustion,organized in orthogonal vortex flows,was established and the experimental studies on the fast ignition and stable combustion of coarse coal particles in this combustor were carried out.The flame temperature versus ignition time and the practical fast ignition the temperature fields in SCC were obtained.These results whow that it is possible to obtain highly efficient and clean combustion of unground coal particles by using this technology.     

天然气炭黑燃烧特性的热天平研究

利用热重分析天平对天然气扩散火炬中直接取样得到的炭黑的燃烧性能进行了研究,并选用了蜡烛炭黑、4种商业炭黑以及一种无烟煤焦炭作为对比。基于试验结果确定了燃烧动力学特性参数,并分析了它的燃烧特性。天然气扩散火焰中生成的炭黑具有着火相对容易、着火温度较低（与煤焦或挥发份较低的煤比）、前期燃烧较弱、后期燃烧较缓慢、燃尽时间较长等燃烧特性。这些结果为利用天然气燃烧过程的炭黑生成强化火焰辐射特性并进行有效控制提供了依据。     

高炉瓦斯灰燃烧性能研究

对高炉瓦斯灰在空气气氛和富氧气氛下的燃烧性能进行了研究,结果表明在富氧气氛中燃烧,着火温度降低,燃尽温度前移,可燃指数和稳燃判别指数、综合判别指数均提高。通过与其他煤种对比可知,将瓦斯灰与煤粉混合有助于燃烧,将高炉瓦斯灰与煤粉混合后喷入高炉是利用高炉瓦斯灰的一项可行的技术。     

石灰立窑代焦型煤燃烧特性的实验研究

在SDTQ600差热-热重联用仪上对石灰立窑代焦型煤试样进行了热重分析,研究了不同升温速率对其燃烧特性的影响,并以5℃/min的升温速率将型煤、焦炭和无烟煤块煤试样进行对比。利用马弗炉研究了单颗粒代焦型煤的燃烧速率。结果表明,代焦型煤的燃烧过程经历了干燥预热、挥发份析出、碳粒燃烧和残碳燃尽4个阶段;随着升温速率的增加,代焦型煤燃烧各阶段的反应时间缩短,反应速率加快;当升温速率由5℃/min提高至10和15℃/min时,代焦型煤的着火时间由28.12min下降至14.01和10.13min,其燃尽时间也由36.82min下降至27.59和22.47min。通过对比,型煤在着火、稳燃性能及综合燃烧特性方面最好,而燃尽性能居中;代焦型煤、焦炭与无烟煤块煤3种试样的综合燃烧指数分别为53.25×10-9、30.14×10-9和11.53×10-9。燃烧温度对型煤燃烧速率影响较小,而型煤尺寸对后期燃烧速率影响较明显,减小型煤尺寸可增大燃烧速率;相同条件下,代焦型煤的燃烧速率低于焦炭而高于无烟煤块煤。实验结果可为石灰立窑型煤代焦提供指导。     

Ignition and combustion of boron particles

The successful development of highly energetic boron-based propellants will require a thorough knowledge of the chemical and physical processes controlling ignition and combustion of single boron particles. Significant recent progress on various problems in the field of boron particle combustion makes our goal prospective.

This paper reviews our current understanding of the ignition and combustion processes of single boron particles, including a comprehensive survey of the previous experimental work, theoretical models, and chemical kinetics studies. In addition, this paper presents up-to-date research findings which represent two major research needs strongly recommended by previous researchers.

An experimental diagnostics was developed to study the ignition and combustion of fine-size single particles. The measured ignition delay and two-stage combustion times of single boron particles with sizes of 3 μm are presented. Effects of gas temperature, oxygen concentration, and magnesium coating on boron combustion were examined.

An investigation was performed to resolve long-term contradicting theories regarding the mechanisms which governed the species diffusion across the liquid B₂O₃ layer covering a single boron particle at elevated temperatures. Observations showed that the diffusion of dissolved boron into molten B₂O₃₍₁₎ dominates the diffusion process through the liquid layer. Subsequently, a polymeric vitreous (BO)_n complex is formed through the reaction between dissolved boron and molten B₂O₃₍₁₎. Based upon these experimental findings, an appropriate boron reaction mechanism was obtained by deduction. A theoretical model was then developed to simulate boron particle combustion in two consecutive stages.     

基于灰层累积的焦炭燃烧缩核模型FLUENT数值模拟研究

ANSYS Fluent提供的焦炭燃烧模型中，忽略了碳粒燃烧过程中灰层累积的影响，导致模拟焦炭燃烧速率偏大。为此，基于Fluent原始模型，结合碳粒燃烧过程中灰层积累对燃烧的抑制原理，利用Fluent中User Defined Functions（UDF）模块，提出一种基于灰层累积的焦炭燃烧缩核数学模型，称为“基于灰层累积的动力/扩散控制”燃烧模型。计算结果表明，相比于原始模型，改进模型中炉膛速度与温度分布更符合热力计算值，模拟得到的飞灰含碳量与实际测值基本一致，说明改进模型更加合理，且模拟结果相对准确。     

Interactive processes in gasification and combustion—Part III: Coal/char particle arrays, streams and clouds

A comprehensive review is presented on the interactive transport processes in the gasification and combustion of a cloud of drops and solid particles. The review is divided into three parts. Part I is concerned with the interactive processes for arrays, streams and clouds of drops, Part II presents a review of isolated coal, carbon and porous char particles pertaining to interactive processes, and finally Part III deals with the interactive processes for solid particle arrays, streams and clouds. Isolated particle gasification (pyrolysis and heterogeneous) and combustion were briefly reviewed in Part II. Because of strong analogy of the group ignition and combustion, to porous char ignition and combustion, the literature on porous char combustion was also included in Part II and new results were presented on the internal ignition of porous char particle using Frank-Kamanetsky type of analysis. Part III presents an integrated approach starting from arrays to clouds and gasification to combustion. The interactions occur through processes ranging from pure diffusive to convective transport processes. Approximate criteria for interactive processes are given.

As opposed to liquid drop arrays and clouds, there is no systematic study for arrays of char or coal particles. Due to the similarity between droplet evaporation and char combustion, new results are presented for the combustion of char arrays in quiescent atmosphere. Convective effects are also briefly discussed. Expanding the Frank-Kamenetsky analysis to ignition of clouds, simple solutions are presented for cloud ignition temperatures. A comparison of results between different techniques and between theory and experiment is given.

Interesting results for the ignition characteristics of coal dispersions are obtained in that the particles with relatively small or low volatile matter which ignite heterogeneously when isolated are found to ignite homogeneously under cloud conditions. The minimum ignition temperature is found to increase with decrease in size under isolated mode while the opposite is true under interactions. The problems of the gasification, ignition, and combustion of clouds in confined and unconfined volumes are reviewed.

Experiments conducted with streams (laminar flow reactors, LFR) and clouds (TGA, heated grids, shock tubes, batch of particles in LFR, Hertzberg Ignition apparatus) are reviewed. Following the drop literature, the relation between array and group combustion is presented. Finally, the relevance of the reviewed literature to pollutants' formation and destruction and spray combustion modeling is briefly discussed.     

煤粉颗粒群着火和燃烧过程的数值模拟

建立了一维非稳态球形煤粉颗粒团的群燃烧模型.数值模拟煤粉颗粒团的着火和燃烧过程,获得了颗粒团燃烧火焰随时间的变迁.分析了煤粉颗粒团内部参数和外部环境参数对颗粒团着火和燃烧的影响.随着颗粒团内煤粉浓度的增加,颗粒团的均相着火延迟先减小后增加.增加煤粉颗粒尺寸和降低外部温度都会明显延迟均相着火.环境氧气含量的增加会减小着火延迟,同时增加颗粒团的燃烧速率.模拟计算和文献试验结果的变化趋势相吻合.