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采用TG-FTIR联用技术研究了邯钢喷吹用煤的热解失重过程。结果表明:长治煤、大湾煤、70%长治煤+30%大湾煤的失重过程均大致分三个阶段,450~800℃之间,TG曲线急剧下降,挥发分大量逸出。DTA曲线在590~700℃时出现峰值,煤的热解反应剧烈。分析显示长治煤添加30%比例大湾煤后失重开始温度比原煤下降13.5℃,1000℃时的失重率比长治煤的失重率增加了4.05%,说明无烟煤配加烟煤可以促进煤粉热解过程中产物的转化,有利于改善喷吹煤粉的燃烧状况。FTIR结果显示:添加30%大湾煤对煤粉在热解过程中CO的生成影响不大,CO2则出现减少的趋势。甲烷气体的释放被集中到一定时间段内完成,且释放量有所增加。另外,配煤还促进了其他烃类气体逸出,增加了参加均相燃烧的挥发分气体比例。 相似文献
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对高炉1400℃以上区域的煤粉有效热值进行了研究,结果表明,在高炉下部热平衡为控制因素的操作中,平均挥发分低的煤粉对降低燃料比是有效的.然而,挥发分相对较低的半无烟煤的资源总量是有限的.对低挥发分煤和高挥发分煤的混合煤粉进行了研究.用燃烧实验和模拟分析的方法,考察了混合煤粉的燃烧特性,结果发现,当使用不同挥发分的煤组成的混合煤时,其燃烧温度高于各煤种单独燃烧时燃烧温度的加权平均值.混合煤粉的使用对初期升温有显著的促进作用.这是因为高挥发分煤能形成高温燃烧场,并可促进低挥发分煤的燃烧. 相似文献
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得益于丰富的天然气资源,俄罗斯众多钢铁厂使用天然气进行高炉喷吹。为实现资源的合理配置以及效益最大化,提高高炉喷煤量、减少天然气使用成了新利佩茨克钢铁公司发展新方向。对俄罗斯所提供的两种高挥发分煤(1号、2号)和2种挥发分含量较低的煤(3号、4号)以及经配煤处理后的混煤进行工业分析和着火点、爆炸性、灰熔点等喷吹特性研究。研究发现1号和2号煤具有强爆炸性和较低的着火点,而3号和4号煤着火点较高,燃烧率较低。4种煤粉均不适于高炉单独喷吹。经混煤处理后的煤粉无爆炸性,燃烧率高于贫瘦煤,着火点介于对应2种单煤之间,灰分的质量分数均低于8%,低于国内高炉喷吹用煤对灰分要求。但俄罗斯煤的可磨性普遍较差。在所设定的混煤方案中,2号烟煤与4号贫瘦煤的混煤着火点适中、燃烧率较高、可磨性较好,较适合高炉喷吹,其中2号烟煤占40%时最适合高炉喷吹。 相似文献
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Jiu-gang SHAO Jian-liang ZHANG Guang-wei WANG Zhe WANG Hong-wei GUO 《钢铁研究学报(英文版)》2014,21(11):1002-1008
Non-isothermal combustion kinetics of two kinds of low volatile pulverized coals (HL coal and RU coal) were investigated by thermogravimetrie analysis. The results show that the combustibility of HL coal was better than that of RU coal, and with increasing heating rate, ignition and burnout characteristics of pulverized coal were improved. The volume model (VM), the random pore model (RPM), and the new model (NEWM) in which the whole combustion process is considered to be the overlapping process of volatile combustion and coal char combustion, were used to fit with the experimental data. The comparison of these three fitted results indicated that the combustion process of coal could be simulated by the NEWM with highest precision. When calculated by the NEWM, the activation energies of volatile combustion and coal char combustion are 130.5 and 95.7 kJ · mol^-1 for HL coal, respectively, while they are 114.5 and 147.6 kJ ·mol^-1 for RU coal, respectively. 相似文献
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研究不同半焦与喷吹煤粉的燃烧性能有利于半焦进行高炉喷吹、降低炼铁成本。通过改变热解温度、热解升温速率、热解保温时间和热解气氛在管式炉中制备了不同的半焦样品,通过工业分析和热重试验、结合比表面积、发热量和活化能变化对不同热解半焦和两种喷吹煤粉燃烧性能差异进行了分析。结果表明,不同热解条件下制备的半焦,其燃烧性能大多介于两种喷吹煤之间,热解温度是影响半焦反应性能最重要的因素,热解温度对活化能的影响呈现先减小后增大的趋势。不同热解温度制备的半焦孔隙结构均比喷吹煤发达,且累积孔容积和比表面积均呈现先增加后减少的趋势,孔隙特点与燃烧性能基本对应。550 ℃是制备高反应性半焦较适宜的热解温度。可以通过控制热解条件制备高反应性半焦,这有利于半焦在高炉喷吹中的应用。 相似文献
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为了研究稀土氧化物CeO2对高炉喷吹煤粉的助燃机制,以某炼铁厂高炉喷吹煤粉为原料,利用煤粉燃烧炉进行煤粉燃烧试验并收集未燃煤粉,通过热重-差热法分析CeO2对喷吹煤粉的助燃机制,结合XRD和SEM检测分析未燃煤粉.结果表明:助燃剂CeO2对喷吹煤粉的助燃效果显著,其添加比例控制在1.5%(质量分数)左右比较适宜;CeO2在煤粉固定碳表面上形成络合盐Ce4+(CO-)4,减弱了两相反应物间的势能垒,促使挥发分的开始燃烧放热温度降低,固定碳燃烧温度区间变窄;随着CeO2的加入,Ce4+ (CO)4成倍增长,在XRD图谱中表现为未燃煤粉的微晶尺寸逐渐增大;在CeO2的作用下未燃煤粉颗粒的平均粒径与原煤未燃煤粉颗粒的平均粒径相比减小了3.48 μm,表面出现大量孔洞结构. 相似文献
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高炉喷吹煤粉燃烧性与反应性的研究与应用 总被引:1,自引:0,他引:1
为了研究高炉喷吹煤粉的冶金性能,采用热重分析法对6种无烟煤和1种烟煤进行燃烧性与反应性研究。结果表明,与无烟煤相比,烟煤在不同温度下的燃烧性和反应性均明显高于无烟煤。混煤的燃烧率实测值大于加权值,使用混煤可以发挥无烟煤和烟煤各自的优点,加快燃烧过程,提高混煤燃烧率。随着混煤中粒度小于74 μm煤粉所占比例的增加,燃烧率增大。在高煤比喷吹条件下,混煤煤粉粒度小于74 μm的比例控制在75%左右。结合无烟煤的燃烧性和反应性试验结果,建议喷吹煤粉采购中应尽可能多地采购无烟煤C资源,同时控制无烟煤E的采购量;高炉提煤比操作中应将无烟煤C确定为喷吹用无烟煤的首选煤种,以提升混煤燃烧率和发挥未燃煤粉保护焦炭的作用。 相似文献
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采用固定床热解装置制备神木长焰煤与凤眼莲和冶金工业固体废弃物热解终温分别为450和550 ℃的共热解半焦;利用管式沉降炉模拟高炉喷吹条件研究共热解半焦的燃烧性能,并考察了热解终温和共热解物质对半焦燃烧性能的影响。研究表明:高炉瓦斯泥和冷轧氧化铁红的加入起到催化煤热解的作用,其中高炉瓦斯泥的催化热解效果最优,挥发分析出的增幅为18.4%;煤与冷轧氧化铁红在热解终温550 ℃时共热解半焦的燃烬度最佳为98%,与550 ℃时的原煤半焦的燃烬度相比,提高了22.5%;SEM扫描电镜结果显示,煤与冷轧氧化铁红共热解半焦与原煤半焦相比,半焦表面产生了更多的裂纹;除煤与轧钢氧化铁皮及煤与高炉瓦斯泥共热解半焦外,试验所制备的其他共热解半焦的各项性能均符合中国喷吹用煤指标。 相似文献
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以邯郸钢铁公司2种高炉喷吹用煤粉作为原料,用马弗炉进行预热,测定不同温度预热后的失重率和燃烧率,并采用扫描电镜(SEM)观察预热后煤粉表面结构的变化。试验结果表明,烟煤150℃预热时的失重率为512%,且随着预热温度升高,煤粉的失重率增加,预热温度300℃时失重率可达到17.24%。无烟煤预热后失重率变化不大,预热温度为300℃时失重率仅为5.66%。预热后煤粉燃烧率明显升高。300℃预热条件下的烟煤燃烧率为89.74%,相对于原煤提高了15.67%,无烟煤燃烧率为85.19%,相对于原煤提高了24.80%。预热后煤粉表面结构发生了明显变化,层状和孔隙结构增加,从而提高了煤粉的燃烧率,为提高预热煤粉的燃烧率提供了理论基础。 相似文献
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建立了煤粉燃烧率通用模型,模型可以根据煤粉的工业分析值计算燃烧动力学参数并预测煤粉燃烧率.通过对比前人的实验数据,验证了模型的准确性,同时研究了影响高炉煤粉燃烧率的若干因素.研究结果表明:在高炉喷煤过程中,煤粉颗粒在2 ms左右就可以达到热风速度,由于煤粉颗粒在直吹管内停留时间短并且温度较低,因此在直吹管内煤粉不会发生燃烧.煤粉进入风口回旋区后,挥发分瞬间全部析出,并且颗粒粒径越小,挥发分开始析出时间越早.降低煤粉粒径和增加氧气体积分数均有利于提高煤粉燃烧率.氧气体积分数每增加1%,燃烧率提高2%.随着喷煤量的增加,煤粉燃烧率逐渐降低.当提高煤粉喷吹量时,为了保证较高的燃烧率,实际操作过程中应提高富氧率并适当降低煤粉粒径. 相似文献
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Sushil Gupta Veena Sahajwalla Yaser Al-Omari David French 《Metallurgical and Materials Transactions B》2006,37(3):457-473
The influence of carbon structure and mineral matter of three pulverized coals on their char characteristics including reactivity
was studied under a range of combustion conditions in a drop tube furnce (DTF) and thermogravimetric (TGA) furnace for PCI
application. Physical and chemical properties of coals and their combustion derivatives were characterized by automated reflectogram,
X-ray diffraction, scanning electron microscope, and BET N2 adsorption. The QEMSCAN technique was used to characterize the heterogeneous nature of minerals of discrete coal particles.
The TGA char reactivity was related to the proportion of coal particles displaying strong association of calcium/sulfur phases
with carbon matrix to highlight the catalytic influence of minerals on char reactivity at low temperatures. The study suggested
that during DTF combustion tests at 1200 °C, char reaction rates might have been catalyzed by coal minerals, particularly
due to illite and its association with carbon. Under the same combustion conditions, most of the coal minerals did not transform
significantly to slag phases. Coal burnout was found to improve significantly in a combustion temperature range of 1200 °C
to 1500 °C. The improvement of coal burnout with temperature appeared to be influenced by coal properties, particularly as
a function of the chemical nature of minerals, as well as the degree of associations with other minerals. The study implies
that coals with similar mineral compositions might not necessarily reflect similar combustion behavior due to the differences
in their associations with other phases. The study highlighted the significance of the characterization of the heterogeneity
of coal particles including mineral associations for a comprehensive and reliable assessment of the combustion performance
of PCI in an operating blast furnace.
QEMSCAN is a trademark of Intellection Pty Ltd., Milton, Queensland, Australia. 相似文献
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Four chars prepared from pulverized coals were subjected to non-isothermal and isothermal combustion tests in a thermogravimetric analysis(TGA)device.Three different test methods,i.e.,non-isothermal single heating rate(A),non-isothermal multiple heating rate(B),and isothermal test(C),were conducted to calculate the kinetic parameters of combustion of coal char.The results show that the combustion characteristics of bituminous coal char is better than that of anthracite char,and both increase of heating rate and increase of combustion temperature can obviously improve combustion characteristics of coal char.Activation energies of coal char combustion calculated by different methods are different,with activation energies calculated by methods A,B and C in the range of 103.12-153.77,93.87-119.26,and 46.48-76.68kJ/mol,respectively.By using different methods,activation energy of anthracite char is always higher than that of bituminous coal char.In non-isothermal tests,with increase of combustion temperature,the combustion process changed from kinetic control to diffusion control.For isothermal combustion,the combustion process was kinetically controlled at temperature lower than 580℃ for bituminous coal char and at temperature lower than 630℃ for anthracite char. 相似文献