北票油页岩化学渗透脱挥发分模型及氮元素析出预测

以北票油页岩为研究对象,通过13C NMR和TG-FTIR实验检测,研究北票油页岩碳骨架组成以及不同升温速率下的热解特性,计算北票油页岩的热解反应动力学参数,进而构建CPD模型。基于CPD模型,采用全局自由基理论方法,获得针对北票油页岩的氮元素析出预测模型。结果表明：随着热解终温的提高,油页岩中脂肪族碳化合物呈现下降趋势,与之相反,油页岩中芳香族碳化合物则呈现明显的上升趋势,表明北票油页岩在热解过程中脂肪族化合物分解产生油气组分,而一些长链烷烃组分则发生缩聚等芳构化反应,进而导致了含量的升高;北票油页岩在各升温速率下最大失重率均为18%左右,说明升温速率对于油页岩的质量损失无明显作用;北票油页岩在不同升温速率下都有4个明显的下降阶段,说明油页岩的热解失重变化主要经历了4步反应。北票油页岩氮析出过程主要分为3个阶段,随着反应过程的进行氮元素析出量呈上升趋势,在脱挥发分的初始阶段氮元素参量保持平稳,随着热解程度的加深在200 ms后,曲线开始趋于平缓,油页岩中氮元素的析出量达到最大值。

CPD Model and Prediction of Nitrogen Precipitation for Beipiao Oil Shale

Taking Beipiao oil shale as research object,the 13C NMR and TG-FTIR experiments were used to study the carbon skeleton composition and pyrolysis characteristics of Beipiao oil shale at different heating rates. The pyrolysis reaction kinetic parameters of Beipiao oil shale were calculated, and then the CPD model was constructed. Based on CPD model and global free radical theory, a prediction model for nitrogen precipitation in Beipiao oil shale was obtained. Results show that with the improvement of the terminal temperature pyrolysis oil shale in aliphatic carbon compounds showed a trend of decline, in contrast, the aromatic carbon compounds in oil shale are obvious rising trend, that of the shale in the process of pyrolysis aliphatic compound to produce oil and gas components, and some of the specific provisions of long chain alkane group aromatization reactions such as condensation occurred, leading to the increase of the content. The maximum weight loss rate of Beipiao oil shale is about 18% at each heating rate, indicating that the heating rate has no significant effect on the mass loss of oil shale. The Beipiao oil shale has four distinct decline stages at different heating rates, indicating that the pyrolysis weight loss of oil shale mainly goes through four steps. The nitrogen precipitation process of Beipiao oil shale can be divided into three stages. With the progress of the reaction process, the nitrogen precipitation amount shows an upward trend, and the nitrogen parameters remain stable in the initial stage of devolatilization. With the deepening of the pyrolysis degree, the curve tends to be gentle after 200 ms, and the nitrogen precipitation amount in oil shale reaches the maximum.