Evaluation of Linear Kinetic Methods From Pyrolysis Data of Spanish Oil Shales and Coals

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 range, C min -1 Total weight loss, % (Conversion) Oil & water, wt.% 0.2-1. 8 13.5 7.3 0.2-2. 4 12.93 7.7 1.0-2.…”

Section: Table Experimental Data Heating Rate Versus Total Weight Lmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Al-Ayed¹,

Al-Harahsheh²,

Khaleel³

et al. 2009

“…Olivella and Heras [31] used nonisothermal thermogravimetry to study kinetics of degradation of fossil fuels: the apparent activation energy of degradation of two oil shales from the Ribesalbes basin (Type I-S), calculated by the Friedman method, was found to be between 124 and 131 kJ/mol. Olivella and Heras [32] performed linear kinetic methods for pyrolysis of Spanish coals and oil shale and found mean values of apparent activation energies of Ribesalbes oil shale (Type I-S) to be between 195 and 286 kJ/mol. Torrente and Galan [4] obtained apparent activation energy of 167 kJ/mol for non-isothermal TGA of Puertollano (Spain) oil shale.…”

Section: Kinetics Of Thermal Decompositionmentioning

confidence: 99%

Study of the Kinetics and Mechanisms of Thermal Decomposition of Moroccan Tarfaya Oil Shale and Its Kerogen

Aboulkas¹,

Harfi²

2008

127

“…Many authors disagree with the methods based on deriving kinetic parameters from TG/DTG curves, because incoherent results could be gained but Olivella and Heras confirm that Popescu's method is the most accurate method for deriving kinetic parameters from TG curves of oil shale and coal pyrolysis. [12]. The combustion reaction occurs mainly in the stage where combustion of volatile matter and fixed carbon takes place (450-650 ºC), so T m is considered to be 450 ºC, T n is 650 ºC, and the corresponding conversion degrees for each combustion stage are given in Table 3.…”

Section: Determination Of the Kinetic Mechanismmentioning

confidence: 99%

Kinetic Analysis of Co-Combustion of Oil Shale Semi-Coke With Bituminous Coal

Sun¹,

Wang²,

Shen³

et al. 2012

Utilization of the semi-coke collected from oil shale retorts is very important and advantageous. Due to the inflammable property, co-combustion of semicoke with other good quality solid fuels could be effectual. In this research, a kinetic study of the combustion of oil shale semi-coke (SC) mixed with bituminous coal (C) was carried out by thermogravimetric analysis at different heating rates. Popescu's method was applied to analyze the kinetic mechanisms of combustion of oil shale semi-coke, bituminous coal and their blends; Flynn-Wall-Ozawa method was employed to determine the activation energies of those combustion reactions. Based on the obtained results, it was concluded that three-dimensional diffusion model could be implemented either for the combustion process of oil shale semi-coke or for bituminous coal while for their blends the model of random nucleation and growth could be applied. The activation energies of oil shale semi-coke and the blends of semi-coke and bituminous coal decreased in the beginning, and then increased during the combustion process. Activation energies of the blends decreased with increasing amount of bituminous coal.