Oil Shale Pyrolysis in Fixed-Bed Retort With Different Heating Rates

Abstract

Production of oil at pyrolysis of Ellajun oil shale was investigated at different heating rates (0.2-2.8; 2.2-5.0 and 7.0-13.0 °C min-1 in a fixed-bed retort. Total weight loss and oil yield were calculated for the temperature range 610-873 K. Total weight loss of oil shale sample increased from 12.5% to 18% with increasing the heating rate from 0.2 to 13 °C min-1 , whereas shale oil yield (calculated based on Fisher Assay for Ellajun sample) decreased from 80% to 40%. Sulfur content of produced liquid hydrocarbons decreased from 7.4 wt.% to 6.5 wt.% with increasing heating rate and pyrolysis temperature. Density of the produced shale oil increased from 0.947 to 0.982 g cm-3 with increasing heating rate indicating the formation of heavier compounds. The rate of shale oil accumulation was monitored by digital mass scales. Higher heating rates resulted in higher rates of accumulation. The rate of oil and water collection passed through a maximum for different heating rates at different pyrolysis temperatures.

Heating rate effect on fractional yield and composition of oil retorted from El-lajjun oil shale

“…Al-Ayed et al [22,23] studied pyrolysis of oil shale samples in fixed bed retort and reported a decrease in oil yield and an increase in shale oil density with increasing heating rate.…”

Variable Activation Energy Principle to Model Oil Shale Pyrolysis Kinetics

“…In the second increasing range region in the third zone, the reaction rate bounces back to a sharp increase with increasing pyrolysis temperature after a decreasing region as depicted earlier in Figure 3. This region of pyrolysis is characterized by low reaction rate due to the depletion of the reacting material and high activation energy requirement to break C-O and C-C aliphatic bonds [27,28]. Generally, no pyrolysis reactions are observed at temperatures higher than 540 °C, depending upon the type of oil shale.…”

“…Some researchers [29,30] ascribed the high apparent activation energy mainly to the much stronger bond breakage such as aromatization of alicyclic compounds, dehydrogenation and combination of aromatic rings, and rupture of heterocyclic compounds. It is well known [28] that increasing the heating rate increases the density of the generated shale oil liquid. This is in agreement with the increased production of heavy components at high pyrolysis temperatures.…”

Experimental Research of the Pyrolytic Properties and Mineral Components of Bogda Oil Shale, China

“…At present, the development and utilization of oil shale mainly focuses on the following aspects: distillation to produce shale oil, combustion to generate electricity, gasification, and ash utilization [9,10]. The pyrolytic properties and mineral structures of oil shale influence its utilization efficiency [11]. Sadiki et al [12] reported that the optimum pyrolysis temperature of Morocco oil shale was 520-630 °C, and a large quantity of low-sulfur shale oil could be obtained in this range.…”