共查询到20条相似文献,搜索用时 93 毫秒
1.
2.
3.
采用自主研发的单次处理量为3 kg的热解炉装置测定了不同炉温和试验时间下物料的温度分布和挥发分析出率,并利用此数据,获得了褐煤热解的宏观反应动力学参数,从而为褐煤热解工艺包的形成奠定了基础。 相似文献
4.
5.
为研究褐煤干燥过程,利用煤质水分分析仪和微分热重分析方法,对不同粒级的褐煤在不同干燥温度下进行等温干燥试验,得到了样品含水率与干燥时间、干燥速率与含水率的关系曲线。通过粒级分布系数对褐煤进行含水率折算,并用不同干燥模型对试验数据进行拟合,得到了在介质温度140℃下3个干燥阶段的干燥方程及干燥动力学参数。结果表明,引入粒级分布系数得到的干燥速率特征常数k值,与不同粒级的干燥速率特征常数k的均值相近。根据褐煤的干燥速率和水分的存在形式,将褐煤干燥过程分为3个干燥阶段,分析得出干燥方程模型分别用线性干燥模型、Wang经验模型、Page模型较为合理。根据Arrhenius经验公式建立了ln k与1/T的关系,得到褐煤干燥的界面蒸发活化能Ea=17.088 k J/mol,指前因子A=12.47 min~(-1)。 相似文献
6.
橡胶催化热解动力学分析 总被引:1,自引:0,他引:1
利用TG-DTG技术研究了橡胶催化热解过程,并采用多升温速率和单升温速率相结合的方法对热解第一阶段动力学数据进行分析。推导出橡胶热解反应级数为3/2,反应动力学方程为da/dt=2/(3~(1/2)a)·A exp(-E RT),表观活化能为148~162 kJ/mol,指前因子lnA为28~32。 相似文献
7.
升温速率及热解温度对煤热解过程的影响 总被引:1,自引:0,他引:1
为了研究煤热解过程中升温速率及热解温度对热解产物分布及热解过程吸热量的影响,采用热重和热红联用技术对煤热解过程进行了分析.研究了不同升温速率和热解温度对煤热解过程的气态产物分布的影响,并对所产生的焦炭性质进行了分析.结果表明:煤的整个热解过程的吸热量随升温速率的增加而减小;煤热解产生的焦油组分含量包括芳香族、脂环族和脂肪族含量达到最大值所对应的热解温度随升温速率的增加产生滞后现象,但是煤热解产生的煤气成分随着升温速率增加而急剧释放;随着热解温度的升高,焦炭结构逐渐致密,裂纹及裂缝产生,芳香晶核增大,同时焦炭中的氧和氮含量由于含氮和含氧化合物的继续分解而降低. 相似文献
8.
采用热重分析法研究了氮气气氛下竹材的热解行为及其动力学特性,分析了升温速率和粒径对竹材热解过程及动力学参数的影响. 结果表明,竹材热解分为干燥、预热解、热解和缓慢热解4个阶段;升温速率对竹材的热失重特性有显著影响,当升温速率从40℃/min增加到100℃/min时,竹材热解出现了滞后现象,热解活化能从130.87 kJ/mol下降到73.85 kJ/mol,频率因子及反应级数单调减小;不同升温速率下计算的活化能和频率因子之间存在良好的补偿效应;当粒径大于380 mm时,竹材的热解不仅受动力学控制,受颗粒传热、传质影响也较大. 相似文献
9.
以伊敏褐煤提取腐殖酸为对象,采用13 CCP/MASNMR测试技术对腐殖酸的结构特征进行了分析,结合元素分析构建了化学结构模型,根据模拟谱和实验谱的对比修正得到最终的结构模型; 相似文献
10.
通过热重、元素和XRD分析,研究了新疆吉木萨尔县石长沟矿区油页岩在不同升温速率下的热解特性及热解机理. 结果表明,油页岩中有机质热解生成页岩油和热解煤气的反应主要集中在300~550℃;升温速率从3℃/min增至15℃/min,热解反应向高温区移动,有机质完全热解温度从530℃升至575℃. 油页岩有机质的热解动力学分析显示,升温速率从3℃/min增至15℃/min,直接Arrhenius法计算的有机质热解活化能从243.52 kJ/mol增至257.32 kJ/mol;反应转化率从0.02增至0.97,Friedman法计算的活化能从96.39 kJ/mol增至292.84 kJ/mol. 相似文献
11.
The kinetics of coal pyrolysis may be influenced either by chemical reaction or by transport processes, the latter becoming rate-determining at increasing heating rate, particle size and pressure. Quantitative data are reported for those parameters which cause pyrolysis to become transport-controlled. The experiments have been performed with three different coals in H2 and N2, at heating rates ranging from 103 to 104 K s?1, pressure from 0.1 to 150 bar and particle size from 0.063 to 0.8 mm. 相似文献
12.
研究了富含半纤维素的玉米芯(CB)和富含木质素的松木屑(SD)分别与烟煤(YL)程序升温共热解产物产率和组成变化规律,并对焦油族组成进行分析。结果表明:生物质与煤共热解造成热解产物组成和产率显著变化,且其变化程度与生物质的组成和结构有关。对于富含纤维素的玉米芯与烟煤共热解过程,玉米芯质量掺混质量比为75%时,共热解气体产率减小18.87%,其中CO2产率减少29.15%,而热解水产率增加16.77%。由于半焦和玉米芯中碱/碱土金属,尤其是K对焦油中重质组分裂解具有催化作用,共热解焦油中沥青质产率减小43.40%,而极性组分增加63.21%。与富含半纤维素类的玉米芯不同,富含木质素的松木屑与烟煤共热解造成气体和焦油产率增加,而半焦和热解水产率略有减小,气体中CO2和CO略有增加。松木屑中活性H的转移作用,造成共热解焦油中脂肪烃产率增加,极性组分产率减少。松木屑掺混质量比为50%时,脂肪烃增加89.30%,而极性组分减小17.40%。 相似文献
13.
Two types of Rheinische Braunkohle with different mineral matter contents, each with two different moisture contents plus a coke produced from the coal with the lower ash content, were gasified at total pressures between 0.2 and 5 MPa with pure or dry hydrogen, hydrogen/water vapour and argon/water vapour mixtures. In studies with controlled heating (4 K min−1 up to 850 °C) it was found that: 1. methane formation rates and methane yields during gasification in dry hydrogen are drastically lowered with increased moisture of the coals but only at high pressures which reduce evaporation of water; 2. methane formation rates and methane yields during gasification with wet hydrogen (xH2o = 0.02) are generally lowered with all materials; 3. increasing the water content does not further lower the yields or lead to water vapour gasification. Studies at constant temperature (after rapid heating, 100 K s−1) confirmed these results. It was found that increasing the temperature to 950 °C does not eliminate the inhibiting effect of moisture (in hydrogen) if hydrogen pressure is low ≈ ≤ 1 MPa. It was also determined that raising the temperature above 850 °C with a simultaneous increase in pressure up to 5 MPa hydrogen effectively prevented the inhibition by moisture. It was concluded that extremely stable ether bridges are blocking the active sites at the carbon suface and are therefore responsible for the inhibitory effect of moisture in hydrogasification. 相似文献
14.
15.
为获得较好的褐煤半焦制备工艺参数,研究了不同制备条件(热解终温、升温速率、原煤粒径、热解气氛)下制得的乌拉盖褐煤半焦的燃烧性能和燃烧动力学参数。结果表明,热解终温对半焦品质的影响最大,热解升温速率、原煤粒径和热解气氛对半焦燃烧特性的影响不显著。热解终温由350℃升至600℃时,反应指数RI由235℃升至292℃,半焦着火性能变差;燃尽指数Cb由4.68升至6.15,半焦燃尽性能变差;爆炸指数Kd由2.54降至0.46,半焦爆炸倾向性变低;反应活化能由44.4 k J/mol升至63.4 k J/mol,半焦燃烧动力学特性变差。热解终温为520℃时制得的半焦反应指数、燃尽指数、爆炸指数和反应活化能分别为265℃,5.34、0.80和53.2 k J/mol,属于易着火、易燃尽、中等爆炸燃料,燃烧特性良好。 相似文献
16.
为提高褐煤水煤浆的成浆性,以新疆褐煤、半焦及型煤半焦为原料,对其成浆性进行对比分析。结果表明:粗细煤粉质量比6∶4,最佳添加剂用量1.2%时,型煤半焦制备的水煤浆成浆性最好,最大成浆浓度为60.1%,表观黏度为1153 mPa·s。在级配、添加剂用量相同的条件下,褐煤和半焦的最大成浆浓度分别为48.7%和56.8%。煤样工业分析和表面结构研究表明随着提质改性程度的增加,新疆褐煤、半焦及型煤半焦的水分和挥发分依次降低,固定碳升高,孔半径减小,比表面积增大,孔容积变化不明显。说明褐煤经热压提质改性后,煤化度升高,结构渐趋紧密,孔隙率降低,有利于提高褐煤成浆性。 相似文献
17.
Ka-Leung Lam Adetoyese O. Oyedun Kwok-Yuen Cheung King-Lung Lee Chi-Wai Hui 《Chemical engineering science》2011,(24):6505
In literature, the reaction kinetic of pyrolysis process is often determined and modelled under constant heating rates. In reality, the heating rate of an industrial pyrolysis process is difficult or often not necessary to be kept constant. The variation of heating rate at different reaction stages, termed “dynamic heating”, governs the pyrolysis performance such as production rate, energy consumption, product quality, etc. In this work, pyrolysis progress with dynamic heating is being studied. The rate and reaction heat of tyre pyrolysis at different heating rates are obtained experimentally. A transient model considering the effect of dynamic heating was then developed and compared with the conventional static heating model. Results show that a higher heating rate favours the production of volatiles and shifts the overall pyrolysis heat flow to more endothermic. The significance of the dynamic heating model was observed for processes with large feed size and/or with high heating rate. 相似文献
18.
19.
A general criterion is developed for determining whether the selective heating of sulphur-bearing compounds in coal by microwave energy is more effective than conventional heating of the whole sample. Measurements of selective absorption are obtained as a function of microwave frequencies from 1 to 26 GHz. Using very conservative assumptions, it appears that unless absorption by sulphur compounds is 0.8–2.2 dB higher than absorption by other compounds, it is more efficient to use conventional heating techniques. 相似文献
20.
《Fuel Processing Technology》1987,17(1):7-11
The effect of heating rate on the change in radical concentration during coal pyrolysis has been studied using high temperature ESR with a rapid scan unit. The maximum radical concentration of Yallourn coal decreased with an increase in the heating rate. The results were compared with those obtained from a theoretical treatment of the kinetics of radical formation. The effect of a catalyst on the change in radical concentration has also been monitored under rapid heating condition. The maximum radical concentration of the coal/ZnCl2 system showed a significant shift to temperature about 100 K lower than that of coal alone. 相似文献