不同通风条件下的煤颗粒堆积床阴燃传播特性

地下煤火持续燃烧是煤火阴燃蔓延的结果,设计搭建实验室尺度下的煤火阴燃实验模拟装置,研究了煤炭在强制点火后的阴燃传播过程。通过改变每组实验装置的边界通风条件,了解影响阴燃发生和发展的相关因素。结果表明:阴燃过程中煤-氧反应强度主要取决于局部氧浓度,供氧和散热主导下的典型阴燃峰值温度在500～650℃之间;热传导和氧化反应维持着着干燥锋的水平传播;侧边通风加快了边界处煤样的氧化反应进程,峰值温度上升至原来的1～1.2倍,对远离边界的内部煤样升温过程影响逐渐减小直至消失;顶部盖板将浅层煤样中干燥锋传播所需的6.8 h缩短近一半,使其能够提早进入快速氧化阶段,同时限制氧气获取,氧化反应强度降低。     

阴燃转捩为明火燃烧的分岔特性及气相反应临界状态消失分析

通过理论分析研究了燃料阴燃着火-熄火及向明火转捩的分岔特性.以β1为控制参数对燃料阴燃着火-熄火及向明火转捩的发生进行了的分岔分析.计算表明:分岔曲线明显地分为固相着火区和气相着火区,整个变化过程呈现出二次分岔特点.通过气相反应临界状态消失分析可知: ε2=0.05是气相反应的分岔曲线临界状态消失的转变点,ε2值越大,燃料在阴燃越容易发生气相反应,但温度降低;α2=0.53也是气相反应临界状态的一个转变点,α2越大气相反应的温度越接近于固相阴燃温度,而且当α2→ ∞时,只有固相阴燃反应存在而不会发生气相反应.     

颗粒粒度对油页岩燃烧特性的影响

在STA409型热重-红外联用分析仪上进行了桦甸油页岩的燃烧特性实验,得到了升温速率为20℃/min时,颗粒粒度分别为75.66μm、110.05μm、200.21 μm和290.40μm的油页岩的燃烧TG、DTG和DSC曲线,分析了油页岩的燃烧特性及规律.结果表明:油页岩的燃烧是分两步进行的,油页岩在低温段的燃烧以挥发分的燃烧为主;随着颗粒粒度的减小,油页岩的燃烧特性趋好;而高温段主要是有机质、固定碳等难于分解的物质开始燃烧.利用Freeman-Carroll法得到了油页岩在不同阶段的热解反应动力学参数.     

用激光衍射法研究柴油机高压喷雾（Ⅰ）：常温常压下粒度分布特性

本研究在一特制的容弹中,采用经改装的寇明斯PT 喷油系统实现了高压喷雾,喷油压力达130MPa 以上。和曾见报导的用升压器等方法获得的高压喷雾相比,这种喷雾更接近实际柴油机中的喷雾;和用增大普通油泵柱塞直径等方法获得的高压喷雾相比,这种喷雾的喷油压力要大得多。应用Malvern 2604C 型粒子分析仪对高压喷雾的粒度分布及各种影响因素进行了一系列研究。本文是这一系列研究的第一部份,着重报导在常温常压下测定的喷雾粒度随空间和时间的变化规律,因为这是进一步对其他影响因素进行比较研究的基础。结果表明高压喷雾的质量要比常规喷雾有很大的改善。同时,还揭示出在静止介质中喷雾结构的一些细节。     

燃煤锅炉烟气脱硝(SCR法)工艺及特性

结合Haldor Topsoe A/S(丹麦托普索公司)的SCR DeNOx技术,从燃烧机理入手,着重分析选择性催化还原(SCR)脱硝原理,工艺流程,脱硝岛布置方案,还原剂、催化剂选择注意事项,烟道优化设计,运行中工艺参数的控制及工程应用情况.     

燃煤过程亚微米颗粒形成过程的模拟

燃煤中的亚微米颗粒的形成主要经历成核、冷凝和凝并3个过程．通过对颗粒的分布作出一个合理的对数正态分布假设,运用矩方法求解颗粒的通用动力学方程,来研究颗粒的尺寸分布情况．数值计算结果表明,对于不同初始分散性的颗粒,在成核、冷凝和凝并作用下,颗粒的数密度先增大后减小,颗粒的平均体积先减小后增大,分散性先增大后减小,最终趋于一致的均匀程度．对各单个过程的比较结果显示,凝并的作用最大,成核的作用只在颗粒形成的初期,冷凝的作用最小．     

柴油机排气颗粒浓度和粒径分布特征试验研究

研究了6114柴油机不同工况下排气颗粒的数浓度、体积浓度和粒径分布特征,测试工况下柴油机排气颗粒数浓度均呈包括核模态（峰值粒径为10nm-20nm）和积聚模态（峰值粒径为50nm～80nm）的双峰对数正态分布。高转速下排气颗粒数浓度和体积浓度大于中间转速时的数浓度和体积浓度。相同转速下,颗粒体积浓度随负荷增加而增大,而数浓度高转速下随负荷增大而增加,中间转速下随负荷增加没有规律性变化。相同转速下,积聚模态数浓度随负荷增加而增大,核模态数浓度高转速下随负荷增大而增加,但在中间转速下随负荷增加无规律性变化。相同转速下,随负荷增加,核模态峰值粒径有减小趋势。中间转速下积聚模态峰值粒径随负荷增大先增大后减小,高转速下积聚模态峰值随负荷变化无明显变化。中间转速下排气颗粒的核模态峰值粒径小于高转速下核模态的峰值粒径,积聚模态峰值粒径大于高转速下积聚模态的峰值粒径。排气颗粒中核模态粒子占有较大的数量百分比,积聚模态粒子占有较大的体积百分比。     

多波长消光法粒径测量下限影响因素分析

介绍了根据Lambert-Beer定理并采用多波长消光法测量颗粒粒径分布的方法。提出了基于数值模拟和数理统计对多波长消光法粒径测量下限进行估计的方法。通过数值模拟分析讨论了入射光波长、颗粒相对折射率和透光率对粒径测量下限的影响。研究为多波长消光法粒径测量在实际应用中的可行性提供了指导。     

烟颗粒光散射Muller矩阵测量与尺寸、形状参数的研究

对烟颗粒光散射Muller矩阵及其测量原理、测量方法进行了说明,并对依据此测量方法建立的烟颗粒光散射实验平台进行了介绍.根据烟颗粒形状具有分形结构,以及该类颗粒光散射的特点,提出了用光散射Muller矩阵测量烟颗粒回转半径与分形维数的方法,并利用该方法对棉绳阴燃烟颗粒的同转半径进行了测量,结果表明棉绳阴燃烟颗粒的回转半径大致在200-300 nm.     

煤粉浓淡分流及分路燃烧装置及其发展前景

本文简要阐述煤粉浓淡分流及分路燃烧装置的基本原理、结构、优点及其工业应用效果,并对其发展前景进行了探讨。     

Detailed modeling of size distribution functions and hydrogen content in combustion-formed particles

A kinetic modeling approach is proposed to delve into the nature and chemistry of combustion-produced particles. A sectional method is used for the first time on this purpose. It is based on modeling of gas-to-particle transitions by sections containing 125 lumped species with C numbers ranging from 24 to 4 × 10⁸ and H/C ratio ranging from 0 to 1. This allows not only the mass evolution of particles, but also their hydrogen content to be followed. The model is tested in an atmospheric pressure premixed flat flame of ethylene/oxygen with C/O = 0.8 and cold gas flow velocity of 4 cm/s. Comparison of modeled results with experimental data is satisfying in terms of species concentrations and H/C ratio of the particles. Analysis of model results in comparison with the experimental data has shown that it is possible to distinguish different precursors of particles moving from the exit of the burner into the post-oxidation region of the flame. At particle inception, i.e. just downstream from the flame front, gas-phase PAHs are responsible for particle nucleation and oligomers of aromatic hydrocarbons and small pericondensed hydrocarbons are predominantly present. Then the dehydrogenation process takes place and soot formation starts; in this zone large pericondensed and stacked structures are produced. Further up soot maturation generally linked with dehydrogenation is present, but still a few particles with higher H/C and with low coagulation efficiency are produced and remain present along the flame. The model, in accordance with experimental structural soot analysis, shows that in soot particles condensed structures typical of clusters of large pericondensed hydrocarbons are present whereas high-molecular mass condensed species mainly comprise oligomers of small aromatic compounds of clusters of small pericondensed hydrocarbons.     

特高压、超高压输电线路多分裂导线施工技术

对特高压、超高压输电线路多分裂导线各种张力放线技术进行了汇总比较,并通过机具选型计算、工程计算及综合分析,提出导线展放技术的最佳方案。     

Thermal buckling and vibration of functionally graded sinusoidal microbeams incorporating nonlinear temperature distribution using DQM

Thermal buckling and vibration of functionally graded (FG) sinusoidal microbeams with temperature-dependent properties and three kinds of temperature distributions are investigated in this article. As one material length scale is introduced, the modified couple stress theory is capable of predicting the small-scale effects. Material properties of FG microbeams are calculated using the Mori–Tanaka method. Furthermore, temperature-dependent properties are taken into account to investigate the mechanical characteristics of FG microbeams in high–thermal-gradient environment. Motion equations and the associated boundary conditions are obtained simultaneously through variational principle. Then Navier procedure and the differential quadrature method incorporating an iterative procedure are used to solve the governing differential equations with temperature-dependent properties and general boundary conditions. Numerical examples are performed for demonstrating the influences of temperature distribution, beam thickness, material length scale, slenderness ratio, shear deformation, functionally graded index, boundary conditions, and temperature-dependent/independent properties on thermal buckling and free vibration behaviors of FG microbeams.