混合垃圾燃烧特性的实验研究

针对我国目前垃圾焚烧以烧原生垃圾为主的特点，以热重分析和流化床燃烧实验台为主要研究手段，对于混合垃圾的燃烧特性展开深入研究并将二者的试验数据进行了对比。认为：混合垃圾在热重分析仪中的燃烧特性可以用单组分物质的叠加来表示，而混合的垃圾在流化床中燃烧时，用简单的单组分叠加来表示不很合理。图3表5参5     

基于人工神经网络的煤粉燃烧特性预测模型

煤质常规分析指标与燃烧特性参数的综合运用有利于指导电厂的优化运行。对81个煤样进行了热重分析实验并获得燃烧特性参数,利用人工神经网络建立基于煤质分析数据的燃烧特性参数预测模型,并通过相关性分析、遗传算法和多次预测取平均的方法对模型进行优化。结果表明:优化建立的着火稳燃特性指数(R_w)预测模型的拟合度(R~2)为0.957,10个预测样品的平均绝对误差(MAE)为0.15;燃尽特性指数(R_j)预测模型的R~2为0.938,MAE为1.17。在生产现场利用常规分析快速预测煤粉的燃烧特性。     

混合垃圾在热重分析仪中的燃烧特性分析

通过热分析技术,对城市固体废弃物中几种典型组分进行实验研究,得到了混合垃圾在热重分析仪中的燃烧特性,并对城市固体废弃物的混烧规律开展了有益的探讨。     

生物质与煤矸石混合燃烧特性分析

文章利用TG-DTA热重分析仪,对玉米秸秆、向日葵花盘和煤矸石进行混合燃烧试验,研究了混合试样的燃烧特性。结果表明:向日葵花盘较玉米秸秆更易燃烧,燃烧过程更为剧烈、发热量更高,燃烧特性更好,而玉米秸秆燃烧过程较为稳定;两种生物质与煤矸石混合燃烧过程中,向日葵花盘与煤矸石表现出的协同作用更明显;不同含量的向日葵花盘与煤矸石燃烧过程中,随着向日葵花盘含量的增加,着火温度呈现先升高后降低的趋势,最大失重温度呈现先降低后升高的趋势,最大失重率和总的失重率均增大;300℃之前混合试样的转化率相差不大,300～600℃时向日葵花盘含量越高转化率越大,600℃之后向日葵花盘含量越少转化率增加速度越快。     

低氧气氛下煤粉燃烧特性及动力学

采用热重分析仪研究了不同煤粉在烟气气氛下的燃烧特性,考虑了升温速率和氧气浓度对燃烧特性的影响。研究结果表明:低氧条件、高升温速率下,煤粉的TG、DTG曲线均向高温区靠近,燃烧速率变慢,燃尽时间增长;改变氧气浓度和升温速率对煤的着火温度影响不大,在一定氧浓度(5%~15%)范围内,高水分低阶煤采用烟气干燥输送的制粉系统,能满足其安全性要求;氧气浓度和升温速率主要对煤的燃烧阶段产生影响,随着升温速率的升高和氧浓度的降低,燃尽温度明显升高,且氧浓度对燃烧特征参数的影响大于升温速率的影响。此外,采用Coats-Redfern积分法对煤粉在程序升温过程中的燃烧反应做了相应的动力学分析。结果表明:氧气浓度和升温速率的变化均对活化能产生影响,且随着氧气浓度的降低,煤阶对活化能的影响逐渐减弱。     

微富氧条件下煤粉燃烧及NO生成特性的研究

利用热重分析技术对微富氧条件下煤粉的燃烧特性进行了研究,并与富氧条件下煤粉的燃烧特性进行了对比,利用固定床测定了燃煤NO的生成规律,分析了反应气氛和煤种的影响．结果表明：随着氧体积分数增加,微富氧条件下煤粉的燃烧向低温区移动,综合燃烧特性指数S逐渐增大;在相同的氧体积分数下,由于N2和CO2的物性差异,煤粉的微富氧燃烧特性优于富氧燃烧特性,但当氧体积分数升高到40％时,两种气氛的燃烧特性差别不大;反应气氛和煤种均对燃料氮的转化率影响显著;氧体积分数升高或N2的参与会使反应温度上升,影响燃料氮的转化率;煤的挥发分和元素氮的质量分数也会影响燃料氮的转化率．     

洗中煤和煤矸石的混合燃烧特性分析

利用热分析法研究了洗中煤和煤矸石混合后的低热值混煤的燃烧特性,对数据进行分析获得了其燃烧特性峰值温度、着火温度、燃尽温度、综合燃烧特性指数等特征参数,通过动力学分析得到了活化能与频率因子等参数,得出结论:混合比对煤样的着火性能有很大影响和低热值混煤的燃烧过程服从1.5级的化学反应。     

煤粉细度对燃烧特性影响的实验研究

对冷水江和斗笠山两种煤粉,采用热天平进行了热重分析实验,分析了煤粉样在不同细度下的着火特性、燃烧特性、燃尽性能及动力学参数,给出了反映煤粉燃尽性能的综合判别指数Hj并进行了对比.结果表明:在相同的升温速度下,随着煤粉粒径的减小,挥发分析出量及DTG峰值增大,出现最大燃烧速率的时间提前;煤粉粒径减小,活化能降低,着火温度降低,着火提前,煤粉的燃烧特性也随之变好.     

污水污泥的燃烧特性

通过对几种污泥样品热重分析,研究污泥的燃烧特性,根据燃烧实验所得的热失重曲线,对几种污泥的燃烧过程进行了分析。对实验数据进行了处理,采用Phadnis法和微分法相结合的方法确定了燃烧反应机理并求出了反应动力常数Ａ和Ｅ,在燃烧的不同阶段,总反应速率控制因素不同。     

混合垃圾在热重分析仪中的燃烧特性分析

通过热分析技术对城市固体废弃物中几种典型组分进行了实验研究,得到了混合垃圾在热重分析仪中的燃烧特性,同时探讨了城市固体废弃物的混烧规律。     

生物质粉体燃烧特性的研究

文章提出了一种生物质粉体燃烧模型,根据此模型设计了专用的燃烧炉.研究揭示了生物质粉体燃烧特性突出表现为体积特性,其次是粒径特性,同时温度场的分布验证了燃烧模型的合理性.当粉体粒径为0.177mm左右,每千克粉体燃料配送4m3风量时,燃烧效果与破碎成本最优化.而且风粉混合物可以像燃气一样输送、控制和燃烧.这种新的燃烧方式对提高生物质的燃烧效率、改善结渣现象有重大的意义,并为生物质能的利用开辟了一条新途径.     

Combustion and emission characteristics of premixed biogas mixtures: An experimental study

In this study, effects of fuel composition, swirl number and hydrogen addition on combustion and emission characteristics of various biogas mixtures were experimentally investigated. To this end, a laboratory scale combustor and a swirl stabilized premixed burner were designed and manufactured. Later on, this combusting apparatus was equipped with flow, control, safety and measurement tools, hence entire test system was constituted. Combustion and emission characteristics of tested biogas mixtures were determined by measuring temperature and species (CO₂, CO, O₂ and NO) distributions throughout the combustion chamber. Additionally, flame structures of tested biogas mixtures were evaluated by examining flame luminosity, visible flame length and flame thickness from instantaneous flame images. Results of this study showed that both radial and axial temperature distribution variations of tested biogas mixtures differently alter with hydrogen addition based on the gas composition. Although flame temperature increases with swirl number at burner outlet, it presents a non-monotonous dependence on swirl number outside the flame region because of the modified flow characteristics. This is also the case for emissions of CO₂.     

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。     

Combustion characteristics and kinetics of diesel and canola oil samples

In this study, combustion and pyrolysis behavior of diesel and canola oil is investigated using thermal analysis techniques known as thermogravimetry (TG–DTG) and differential scanning calorimetry (DSC) at different heating rates. Reaction regions, peak temperatures, mass loss, heat flow rates, ignition temperatures, and specific heat of diesel and canola oil samples are determined using TG–DTG and DSC data. It was observed that as the heating rate of the reactions increased, peak temperatures of the reactions shift higher; implying that as the heating rate of the reactions increases the reactions lose their sensitivity. Five different kinetic methods were applied to determine combustion reaction parameters of the reactions. It was observed that averages of the activation energies of the samples are in the order of canola oil and diesel for different heating rates.     

柴油/甲醇组合燃烧发动机的燃烧特性与排放

对一台高速直喷式柴油机采用柴油／甲醇组合燃烧方式及其纯柴油燃烧方式的燃烧特性进行了研究。其结果表明，采用柴油／甲醇组合燃烧的发动机，燃烧始点晚于采用纯柴油时的燃烧起点，但是燃烧速度快，气缸峰值压力比燃烧纯柴油时高；与纯柴油的双峰放热规律不同，组合燃烧的放热率曲线呈单峰形；组合燃烧的最高燃烧温度比燃烧纯柴油时有所降低．进而从燃烧理论上解释了采用组合燃烧可以同时降低碳烟和NOx排放的原因。     

Combustion characteristics of droplets of coal/oil and coal/oil/water mixtures

The utilization of coal/oil mixtures in furnaces and boilers appears to be a viable short-to-medium range solution to partially alleviate the demand on petroleum supply with minimum combustor modifications. The present investigation first demonstrates that the combustion characteristics of the coal/oil mixture droplets depend intimately on the intensity of internal circulation. Rapid internal motion favors batch-distillation-type vaporization which causes the coal particles to agglomerate. On the other hand, slow internal motion traps the volatile components in the inner core of the rapidly-heated droplet and may eventually lead to internal boiling and subsequently fragmentation of the droplet. Experimental results reveal a mixed behavior, although the degree of agglomeration is significant even at moderate levels of coal loading. It is subsequently shown that the addition of small quantities of water significantly enhances the potential and intensity of droplet explosion. Practical implications of the present results are also discussed.     

污泥热解油的燃烧特性及动力学模型

利用热重分析(TG)对污泥热解油的燃烧特性进行了研究,污泥热解油的燃烧过程分为两个阶段.第1阶段为轻质有机物挥发后与氧发生均相燃烧,第2阶段为难挥发有机物与氧发生非均相燃烧,其中第1阶段燃烧反应是其失重的主要原因.分析了升温速率对燃烧特性的影响,发现增大升温速率有利于燃烧.对燃烧过程中烟气的排放规律进行了红外分析(FTIR),从另一角度印证了热重分析的结果.根据热重曲线建立动力学模型,分别对不同升温速率下燃烧过程的两个阶段进行动力学参数计算.活化能的变化趋势再次表明提高升温速率有利于污泥热解油的燃烧.     

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.     

Combustion Characteristics and Kinetics of Partial Gasified Coal Char

Abstract

Combustion characteristics and kinetics of partial gasified coal char (PGC-char) were investigated in this article. Two-stage distributed activation energy model (TS-DAEM) and simple model were used to model the combustion kinetics. The experimental results showed that the combustion characteristics of PGC-chars varied with coal types and percentage of gasification. Modeling results showed that TS-DAEM could suitably describe the combustion of PGC-char. The activation energy and preexponential factor increased with the increasing of PGC-char gasification percentage, but the percent of high reactivity part decreased. This indicated that the difficulty reactive part in the partial gasified coal char became more and more with the gasification conversion. However, simple model wasn't fit to describe the combustion of PGC-char, especially for PGC-chars with obvious second peak in combustion DTG curves.