鄂尔多斯长7段油页岩不同阶段热解反应特征

针对原位热采开发油页岩矿藏中热解反应变化复杂、控温困难等问题,通过热重分析实验对鄂尔多斯盆地长7油页岩热解过程进行阶段划分;通过X射线衍射测试、气相色谱-质谱联用等实验重点检测有机质裂解放热阶段的产物成分,分析不同阶段演化的主要化学反应,进一步验证阶段划分。结果表明,油页岩在氮气氛围下的热解可以划分为3个阶段:脱水阶段(<300℃)、有机质裂解放热阶段(300~720℃)、矿物吸热分解阶段(>720℃)。在有机质裂解放热阶段,油页岩的失重约为总失重的74%,无机矿物未发生热裂解。有机质裂解放热阶段可进一步划分为3个阶段:300℃≤T<450℃的低温初始段、450℃≤T<600℃的中温热解段、600℃≤T≤720℃的高温热解完成段。有机质的热解主要发生在中温热解段。随温度升高,烷烃脱氢反应、酯化反应变为以酯类化合物热裂解反应、烷烃断链生成小分子烃类反应为主;温度升至600~720℃时,会促使化合物发生聚合向油页岩半焦转化;当温度控制在中温热解段时,油页岩油成分最好,含27.70%酯类、29.89%脂肪烃、14.49%醇类、12.66%芳香烃等。研究结果为油页岩热解机理分析、油页岩数值模拟模型的建立和提高现场采收率提供理论指导,并对控制有机质的反应温度范围提供依据,保证较高的转化率。

Study on the comparison of the pyrolysis gas release of lignite and its briquette

In this experiment, lignite was refined and processed through binderless briquette preparation process from low-rank coal and became briquette. Then, lignite and its briquette were pyrolysed as materials to compare the nature of their pyrolysis. In this study, the experiment was carried out through a lab tube furnace, at a heating rate of 10 ~C/min, and the gas was analyzed and compared, which was collected at different temperatures. The results show that： in the pyrolysis temperature of 550-850 ℃, the semi-coke yield of briquette is 2%-6% higher than lignite, the tar yield of briquette is 2%-3% higher than lignite and the gas yield of briquette is 4%-9% less than lignite. The time required for complete release of the briquette is about 20 min less than lignite. The components in the pyrolysis gas of lignite and its briquette are the same, and their variation with the pyrolysis temperature is similar.