油页岩半焦矿物组分分析及其与玉米秸秆混烧特性

利用程序升温热分析技术对不同混合比下油页岩半焦/玉米秸秆进行了热重燃烧试验,并对不同燃烧终温下的油页岩半焦进行了X射线衍射XRD(x-ray diffraction)试验。研究了汪清油页岩半焦与玉米秸秆在整个混烧过程中各燃烧组分的变化,考察了汪清油页岩半焦的矿物组分对其影响,采用基于固体分解动力学的TG(thermogravimetric)曲线模拟法得到了混样各阶段燃烧组分的变化曲线。结果表明汪清油页岩半焦矿物质的分解与聚合反应主要发生在873~1023 K;混样的主燃烧阶段包含4个阶段,玉米秸秆的掺入有效促进了混样中挥发分的析出燃烧,并促使矿物质碳酸盐的分解向低温区迁移,而反应级数的改变可以作为各阶段燃烧组分变化的表征。研究结果可为油页岩半焦燃烧的工业化利用提供理论技术支持。

Analysis of mineral composition of oil shale semicoke and its co-combustion performance with cornstalks

Oil shale semicoke, the product of oil refining process at oil shale retorting, possesses more ash content and lower calorific value, and now is mainly treated by piling up. But due to some phenolic compounds, sulfides and polycyclic aromatics contained in the leachates, oil shale semicoke may cause severe damage to the environment at the piling-up process, which has been a bottleneck in the further development and utilization of oil shale, while utilizing the combustion of oil shale semicoke to produce heat is an effective use way. At this foundation the article further explored the utilization possibility of the combustion of oil shale semicoke and biomass. The thermogravimetric combustion experiment of oil shale semicoke and cornstalk blends was conducted with temperature programming thermoanalysis technology, which was to investigate the change of different combustion components of Wangqing oil shale semicoke and cornstalks during the whole co-combustion process. And the X-ray diffraction experiments of Wangqing oil shale semicoke at different burnout temperatures were conducted to explore the influence of the mineral on the combustion of oil shale semicoke. The change curves of the combustion component of Wangqing oil shale semicoke and cornstalk blends were acquired by the thermogravimetric curve simulation method based on the kinetics of solid-state decomposition. The results of X-ray diffraction experiments showed that the decomposition and polymerization reaction of the mineral of Wangqing oil shale semicoke mainly occurred at 873-1 023 K. The thermogravimetric combustion experiment of oil shale semicoke showed that the combustion process of the semicoke went through 4 stages, and the stage of volatiles emission burning went through 2 stages for the semicoke with high ash content, which was different from other oil shale semicokes. The 4 main stages of the combustion of Wangqing oil shale semicoke and cornstalk blends included volatiles emission burning, fixed carbon burning, residual fixed carbon burning and carbonate minerals decomposition stage. The stage of volatiles emission burning went through 1 stage, while the stage of fixed carbon burning went through 2 stages, for the combustion of fixed carbon could not be burned out during one process. The mixed cornstalks promoted the burning of volatiles of the blends and made the decomposition of carbonate minerals migrate to low temperature area. The free energy of activation and the reaction order of the main co-combustion process of the blends were calculated. The results showed that the free energy of activation needed at different co-combustion stages of the blends had distinct limitation, and the free energy of activation at the stage of volatiles emission burning was about 181, 227-233 kJ/mol at the stage of fixed carbon burning, 256-262 kJ/mol at the stage of residual fixed carbon burning, and 288-293 kJ/mol at the stage of carbonate minerals decomposition. The free energy of activation of the blends combustion decreased due to the mixed cornstalk, which also promoted the combustion reaction, and the change of the reaction order could be as the characterization of the combustion component changing in different stages. The study results can provide theoretical technical support for the industrial utilization of the combustion of oil shale semicoke.