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通过动力学计算,结合XRD和气相色谱分析,对降温条件下单煤及以铜渣熔融还原尾渣为载体的煤的热解行为进行了研究. 结果表明,在初始温度1200℃、降温速率6.667 K/min条件下,煤混渣中煤热解最大速率较单煤增大,时间提前6~7.5 min,失重增加4.51%~11.43%;煤混渣热解气体中H2含量增高,原因为渣中CaO组分对煤中芳香环的脱氢效应;单煤及煤混渣样在降温过程中热解及气化反应均属一级反应,煤混渣样初始热解及气化反应表观活化能低于单煤,但主热解区表观活化能大于单煤,原因为主热解区还原性气氛增强,同步发生渣中高价铁氧化物的还原,反应类型增加,表观活化能变大. 相似文献
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不同变质煤热解和气化中燃料氮的转化规律 总被引:1,自引:0,他引:1
利用水平管式炉对不同变质程度煤进行了热解和气化实验,并利用傅里叶红外气体分析仪对热解和气化过程中主要含氮产物的释放规律进行了研究.结果发现,煤的变质程度对煤热解和气化过程中HCN的释放具有重要影响,而对NH3的释放影响较小.对于低变质程度煤来说,挥发分含量较高,而挥发分的深度裂解是HCN产生的主要来源.因此,低变质程度煤热解过程中转化为HCN的燃料氮份额高于高变质程度煤;对于不同变质程度煤在热解过程中转化为NH3的燃料氮份额则大致相当.对不同变质程度煤在CO2气氛条件下气化反应过程中含氮产物生成规律的研究发现,焦炭氮几乎全部转化为NO;转化为NH3的燃料氮份额有所增加;除印尼褐煤外,转化为HCN的燃料氮份额也有所增加;此外,对CO2气化过程中NO的生成机理进行分析,认为焦炭氮的直接氧化可能是NO产生的主要来源. 相似文献
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热分析在煤燃烧和热解及气化动力学研究中的应用 总被引:9,自引:5,他引:9
论述了煤的燃烧、热解、气化反应动力学的常用的单一升温速率法、多重扫描速率法、动力学补偿效应以及分布活化能动力学模型等热分析研究方法,分析了现用热分析动力学方法的局限性;并对反应控制热分析、微热分析技术、微波热分析以及热分析技术与其他分析技术的联用,热分析技术间的联用等热分析新技术在煤的燃烧、热解、气化反应动力学研究上的应用进行了展望. 相似文献
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大同煤不同显微组分富集物焦与CO2反应性研究 总被引:2,自引:0,他引:2
用热重分析仪考察了大同煤惰质组和镜质组富集物焦与 CO2 的气化反应活性 .发现在 95℃~ 1 1 0 0℃范围内 ,大同煤不同显微组分富集物焦与 CO2 的气化反应活性次序为惰质组 >镜质组 ,特别是当气化温度在 1 0 5 0℃~ 1 1 0 0℃时 ,二者之间差异更显著 .分析认为 ,单纯从活化能不能正确描述煤岩显微组分富集物的气化行为 ,必须考虑热解和气化过程中孔结构及比表面的变化 ;不同显微组分富集物焦与 CO2 的反应性和煤的黏结性有关 相似文献
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采用等体积浸渍法制备了Fe/MgO,Co/MgO和Ni/MgO催化剂,利用固定床反应器对石河子烟煤在热解气气氛下的催化热解行为进行了研究,考察热解气在催化剂作用下对煤热解焦油产率、半焦产率、轻重油比例以及焦油族组成的影响,并与相同条件下N2气氛和热解气气氛热解特性进行了对比分析.结果表明,三种催化剂对煤在热解气中的热解都有促进作用,其中Ni/MgO催化剂对提高焦油产率最明显.在气体流量为400mL/min,热解温度为550℃,Ni/MgO为催化剂的条件下,焦油产率为7.33%,与相同条件下在N2气氛和热解气气氛下热解相比,焦油产率分别提高了78%和42%.而Co/MgO催化剂对提高轻油的作用较明显.这表明热解气催化活化对煤热解有较好的促进作用,可抑制缩聚反应,提高焦油的产率和改善焦油的品质. 相似文献
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东胜煤非等温热解特性与动力学参数确定 总被引:1,自引:0,他引:1
采用热重法考察了升温速率对高挥发分弱黏结性东胜煤热解特性的影响,结果表明:煤热解的3个阶段特征明显,最大失重速率温度(Tp)介于430℃ ̄480℃之间,由回归方程得到Tp和升温速率Ф之间的关系式为:Tp=1.124 4Ф+426.95;并采用非等温热重法对东胜煤的热解动力学参数进行了计算,结果表明其热解动力学参数能很好地反映煤的热解状况,东胜煤的反应级数确定为3。 相似文献
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The molecular weight distributions of coal tars and coal char extracts were examined in an effort to learn more about the process of mass transfer during coal pyrolysis. Evidence was obtained which suggests that the majority of the tar evolved during rapid pyrolysis of pulverized coal escapes by a process limited by gas film diffusion. However, there is also some evidence that the tar includes a small amount of heavy material which could have been ejected from the particle in a condensed phase. Data were also obtained which suggest that the tar precursors (within the parent coal) are formed over a wide range of temperature and do not seem to be present as such in the raw coal. The rather large effect of pressure on yields of tar from bituminous coal pyrolysis has previously been attributed to the effect of pressure on evaporation rates of tar precursors from the particle surface. This study shows that the molecular weight distributions of both the tar and extractable tar precursors within the particle are consistent with such a mechanism. 相似文献
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Akira Iwashita 《Fuel》2004,83(6):631-638
Various types of coals were subjected to the pyrolysis at 300 and 400 °C (mild pyrolysis), and the removal of Hg from coal was determined. The removal efficiency of Hg greatly varied with coal type from 20 to 80%. The removal efficiency was dependent neither on the specific surface area of coal nor on the particle size of coal. The leaching of Hg from coal was tested using sulfur-containing chelating agents such as 3-mercaptopropionic acid (MPA). The Hg leaching efficiency also varied greatly with coal type. There was a good correlation between the degree of %Hg leaching in the MPA leaching and that of %Hg removal in the mild pyrolysis. 相似文献
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Xiangchun Liu Jun Hu Ruilun Xie Bin Fang Ping Cui 《Frontiers of Chemical Science and Engineering》2021,15(2):363-372
A mixture of Pingdingshan lean coal and acid-treated Huadian oil shale was co-pyrolyzed in a drop-tube fixed-bed reactor in the temperature range of 300℃–450℃.To reveal the formation mechanism of the solid co-pyrolysis product,changes in some physicochemical properties were investigated,using analysis by X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy,pore analysis,thermogravimetry,and electron spin resonance.X-ray diffraction showed that the lattice plane spacing for the co-pyrolyzed mixture decreased from 0.357 nm to 0.346 nm and the average stacking height increased from 1.509 nm to 1.980 nm in the temperature range of 300°C–450°C,suggesting that pyrolysis treatment increased its degree of metamorphism.The amount of oxygen-containing functional groups and pore volume decreased with increasing temperature.Thermogravimetry and electron spin resonance results showed that synergistic effects occurred during the co-pyrolysis process.A formation mechanism for the solid product was proposed.Hydrogen-rich radicals generated from the pyrolysis of the oil shale were trapped by hydrogen-poor macromolecular radicals of the intermediate metaplast produced from coal pyrolysis,thereby increasing the yield of solid product. 相似文献
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对平朔煤在不同温度下进行了热解研究,考察了热解温度对煤热解产物产率和热解气性质的影响规律。研究表明,对上述煤样,随煤的热解温度升高,半焦产率下降,干馏气产率增加;液体率在一定温度范围内先增后降,在600℃左右达到最高。热解温度升高,热解气中H2的含量就越高,热解气中CH4的含量在热解温度550~650℃左右达到最高。随热解温度的升高,CO2的含量显著降低,烃类组分随温度升高是先升后降,峰值出现在600℃左右。 相似文献
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基于热重分析和固定床热解实验,研究了升温速率和温度对高矿物质含量的炼焦煤尾煤热解特性的影响. 尾煤热解过程可分为室温至400, 400~600及600~950℃三个阶段. 尾煤与焦煤热解曲线基本吻合,尾煤热解特征温度略向高温区推移. 采用Coats-Redfern积分法拟合计算了尾煤热解的动力学参数,得出反应活化能为22.6~66.2 kJ/mol,热解过程可用3个二级反应描述. 30 g尾煤固定床实验结果表明,氢气在低于400℃析出很少,400~600℃缓慢析出,之后随温度升高析出增加,600℃后大量析出,900℃左右达到最大析出量. 终温950℃时,30 g尾煤热解产气4300 mL,氢气产量1722 mL;焦煤产气7950 mL,氢气产量2716 mL. 尾煤热解富氢气体产量达焦煤热解气产量的54%,具有较高的再利用价值. 相似文献