El-Lajjun Oil Shale Research Articles

Energy efficient method of supercritical extraction of oil from oil shale

The only method currently used for producing oil from oil shale is high temperature retorting, which is wasteful of energy and gives oil with a high content of heavy oil. The novel method of extraction used in this study, involving supercritical propane with tetrahydrofuran as a co-solvent, solves the problem of the high cost of producing oil by conventional high temperature retorting. El-Lajjun oil shale from Jordan was used to evaluate the reaction yield and the characteristics of the product. At supercritical propane temperature and pressure (100 °C and 4.3 MPa), the yield was high and comparable to that for the conventional retorting method (>350 °C). As the temperature increased to 200 °C, the oil yield increased with pressure. The oil obtained was high in aliphatic hydrocarbons but with significant amounts of ethers, some carbonyls and sulfur-oxygen compounds. Hydrodeoxygenation and hydrodesulfurization of the produced oils using NiMo-Al-SBA-15 catalysts significantly enhanced the quality of the oil by decreasing the oxygen and sulfur contents and increasing the aliphatic and diesel fractions.This work leads to an enduring breakthrough technology that substantially reduces costs, waste, energy and the environmental impact of using oil shale as a raw material for liquid fuel production using Green Technology. Recovery of THF is high (>95%) and re-use of THF and propane would be essential for commercial application.

Low temperature retorting of Jordanian oil shales using semi-continuous apparatus

Two oil shales from Jordan, El-Lajjun (EL) in the centre of the country and Isfir Al-Mahata (IA) in the south, have been analysed by elemental analysis, XRF, XRD, FTIR, TGA and 13C NMR. Both oil shales have high S contents and atomic H/C ratios. The calorific value of EL (1630 ± 10 kcal/kg) was similar to that of IA (1571 ± 13 kcal/kg). IA has higher moisture content (7.1 ± 0.3 wt% db) than EL shale (0.7 ± 0.2 wt% db); higher CaCO3 content (XRF, XRD) and lower P content (XRF, XRD). FTIR and 13C NMR indicated a high content of aliphatics for both oil shales, especially for IA shale. These oil shales have been pyrolysed at 300 °C and 320 °C for 7, 14 and 21 days under a constant flow rate of N2. The lower-temperature, long-time reaction yields and analyses of the products were compared with those obtained from the standard Fischer Assay method (520 °C for 90 min). EL oil shale was less reactive than IA oil shale, particularly at lower reaction time. For both oil shales, as the reaction time increased from 7 to 21 days, the oil yield increased to 83–90 wt% of the Fischer Assay oil yield.Fischer assay and lower-temperature, long-time reaction products were analysed using gas chromatography-mass spectrometry (GC–MS) and 1H NMR. The GC–MS results for both shales showed that all the reaction products were similar and of high aliphatic content. Higher diesel fraction was obtained for 21 day reactions at 320 °C. Homologous series of sulfur-containing organic compounds (thiophenes and benzothiophenes) were present in considerable amounts in both EL and IA reaction products. The 1H NMR measurements suggested that the Fischer assay and long-time, lower-temperature reaction products all had high aliphatic content, matching the results obtained from GC–MS measurements.

Effect of air and oxyfuel staged combustion on oil shale fly ash formation with direct in-furnace limestone addition for sulphur retention

El-Lajjun oil shale fly ash formation and S retention during in-furnace limestone injection were investigated in this work. Staged air-firing and 27% O2/CO2 combustion was performed at 1200 °C in a vertical once through reactor. Ash samples were collected at 2.5 m far from the burner and from the conductive section of the reactor. Limestone was added with oil shale before burning in both combustion modes. Ultimate, proximate, and XRF analyses were done for all collected samples, while XRD and SEM analyses were performed for some of them. Sulphur retention in the convective section increased by 13% compared to the radiative section of the reactor. Sulphur retention in the collected ashes ranged from 22 to 32% and 35 to 45% at 2.5 m from the burner and at the candle filter, respectively. The combustion mode had a slight effect on the collected ashes chemical composition. In both combustion modes, the ash samples were enriched with lime and depleted in sulphur, which proved sulphur capture. Fly ash particles were spherical in shape with some aggregates. XRD analysis showed that the main crystalline phases formed in the produced fly ashes were the same regardless the combustion mode and environment, some differences in the relative intensities of anhydrite and lime peaks were present.

Long time, low temperature pyrolysis of El-Lajjun oil shale

There is continuing interest in in situ production of oil from oil shale, particularly for deep deposits and for environmental reasons. Such production would involve long-time, low temperature pyrolysis. Accordingly, reactions of El-Lajjun oil shale have been carried out under N2 for 7, 14 and 28 days at temperatures in the range 240–320 °C. The conversion plateaued at 300 °C and above at a value of about 80 wt% dmmf and was the same for 7 and 14 day pyrolysis. The total conversion decreased by 15% as the temperature decreased to 280 °C. The lower conversions at 240 and 260 °C were the same for 14 and 28 days but oil yield increased at the expense of asphaltene for the longer time. Sulfur content of the oil + asphaltene decreased with increasing reaction temperature (240–300 °C) and time (280–300 °C) from 13 wt% to a plateau of about 7 wt%. The characteristics of the oil and oil + asphaltene changed steadily with temperature up to 300 °C, but increasing the temperature further to 320 °C had little effect. The results show that high conversion to products of good characteristics can be obtained for reactions at sufficiently long times at temperatures as low as 300 °C.

Oxyfuel technology: Oil shale desulfurization behavior during staged combustion

A high sulfur content in Jordanian oil shale is considered one of the biggest challenges preventing its full utilization. To resolve this issue, direct limestone injection during staged combustion has been investigated for the simultaneous control of NO and SO2 emissions. Staged El-Lajjun oil shale combustion under oxyfuel conditions and conventional air-firing conditions was performed at 1200°C in a 20-kW vertical reactor. Limestone was mixed with oil shale before combustion. Three different molar ratios of Ca/S, three different burner oxygen ratios (0.75, 0.85 and 0.95) and different positions of the burnout oxidant probe were tested in both firing conditions to determine the optimum conditions for the lowest SO2 and NO emissions. The SO2 emissions were significantly lowered by adding limestone during staged air-firing and OF27 (27% O2/73% CO2 environment) combustion. The desulfurization efficiencies ranged from 32 to 61% and from 25 to 60% during the staged air-firing and staged OF27 combustion, respectively. The staging level, the Ca/S molar ratio and the position of the secondary oxidant are important parameters that affect the desulfurization efficiency. Higher desulfurization efficiencies were obtained during OF27 combustion compared with air-firing at burner oxygen ratios of 0.85 and 0.95. At a burner oxygen ratio of 0.75, the opposite trend was observed. The SO2 emissions during staged combustion were significantly higher than those during unstaged combustion in air and during OF27 combustion. This was due to high competition among many reactions, which minimized the desulfurization efficiency. The maximum desulfurization efficiency during staged OF27 combustion was 60% with λ=0.85 and Ca/S=2 at 1m from the burner. During air-firing combustion, the maximum desulfurization efficiency was 61% with λ=0.85 and Ca/S=3 at 1.5m from the burner. Based on the current and previous studies, the authors recommend that oxyfuel technology be used for oil shale combustion so that CO2, SO2 and NOx emissions can be simultaneously controlled.

Oxyfuel technology: Oil shale desulphurisation behaviour during unstaged combustion

Abstract A high sulfur content in Jordanian oil shale is considered one of the biggest challenges preventing its full utilization. To resolve this issue, direct limestone injection during staged combustion has been investigated for the simultaneous control of NO and SO 2 emissions. Staged El-Lajjun oil shale combustion under oxyfuel conditions and conventional air-firing conditions was performed at 1200 °C in a 20-kW vertical reactor. Limestone was mixed with oil shale before combustion. Three different molar ratios of Ca/S, three different burner oxygen ratios (0.75, 0.85 and 0.95) and different positions of the burnout oxidant probe were tested in both firing conditions to determine the optimum conditions for the lowest SO 2 and NO emissions. The SO 2 emissions were significantly lowered by adding limestone during staged air-firing and OF27 (27% O 2 /73% CO 2 environment) combustion. The desulfurization efficiencies ranged from 32 to 61% and from 25 to 60% during the staged air-firing and staged OF27 combustion, respectively. The staging level, the Ca/S molar ratio and the position of the secondary oxidant are important parameters that affect the desulfurization efficiency. Higher desulfurization efficiencies were obtained during OF27 combustion compared with air-firing at burner oxygen ratios of 0.85 and 0.95. At a burner oxygen ratio of 0.75, the opposite trend was observed. The SO 2 emissions during staged combustion were significantly higher than those during unstaged combustion in air and during OF27 combustion. This was due to high competition among many reactions, which minimized the desulfurization efficiency. The maximum desulfurization efficiency during staged OF27 combustion was 60% with λ = 0.85 and Ca/S = 2 at 1 m from the burner. During air-firing combustion, the maximum desulfurization efficiency was 61% with λ = 0.85 and Ca/S = 3 at 1.5 m from the burner. Based on the current and previous studies, the authors recommend that oxyfuel technology be used for oil shale combustion so that CO 2 , SO 2 and NO x emissions can be simultaneously controlled.

Shale Oil Solvent Extraction of Central Jordan El-Lajjun Oil Shale

The extraction of the organic matter (OM) from oil shale (OS) can be achieved by several processing techniques. Normally, these techniques can remove high proportion of the organic material contained in oil shale. In this work, organic solvents extraction experiments were implemented to investigate the effect of various parameters on Jordanian El-Lajjun oil shale extractability. Results indicate that the approximate organic matter content in studied El-Lajjun oil shale is 17.48%, and 75% of OS sample particles diameters are less than 270 μm. The grain size has minor effect on shale oil extraction via organic solvents. Among eleven solvents used, the highest yield is obtained via the tetrahedrofuran (THF), whereas, with the use of solvent mixtures, the highest bitumen yield is obtained through the mixture of THF and toluene. The solvation variability is related to mode of extraction and various physicochemical factors such as extraction temperature, pressure, solvent type and mixing time, which result in different OM yield. The results indicate that the solvent extraction could be potential for shale oil extraction from Jordanian El-Lajjun OS under certain conditions of temperature, pressure and solvent type used.

Oxyfuel technology: NO reduction during oxy-oil shale combustion

Nitrogen oxides are one of the major environmental problems arising from fossil fuels combustion. Oxyfuel combustion is one of the most promising clean coal technologies for pulverized fuel-fired power plants to control and avoid CO2 emissions; with this technology NOx emissions are significantly reduced.Due to the importance of oil shale utilization in Jordan and all over the world, this study continues with our previous work on oil shale combustion. Unstaged and staged air-firing and oxyfuel combustion were carried out using Jordanian oil shale collected from El-Lajjun area. The reduction of simulated recycled NO has been investigated in a 20kW vertical reactor. The actual situation has been simulated by injecting NO in the reactor through the burner. It was found that the simulated recycled NO reduction efficiency is affected by the media and the mode of firing. The simulated recycled NO is reduced efficiently (60–70%) during unstaged oxyfuel combustion as well as air-firing of El-Lajjun oil shale. The reduction of the injected NO is more efficient with staging compared to unstaged combustion mode for both air-firing and oxyfuel combustion. The reduction of the injected NO for combustion in air ranges from 61% (without staging) to 100% (with staging) whereas for combustion in 27% O2/73% CO2, it ranges from 57% (without staging) to 100% (with staging). Moreover, El-Lajjun oil shale ashes are characterized as being high in CaO and SiO2, low in Al2O3, SO3, and P2O5 and with minor amounts of F2O3, MgO, Na2O, K2O, and TiO2.

OIL SHALE PYROLYSIS AND EFFECT OF PARTICLE SIZE ON THE COMPOSITION OF SHALE OIL

Samples of Ellajjun oil shale were pyrolysed under nitrogen environment to the final pyrolysis temperature of 550 °C. The particle size of the samples under study was varied from 10 to 40 mm. The effect of particle size on weight loss and oil yield was investigated at a constant heating rate of 2-3 °C/min. Increasing particle size from 10 to 40 mm decreased the total sample weight loss from 27 to 21% at the same final pyrolysis temperature. At the same time, gas weight loss decreased from 10 to 6%. Oil yield was found to decrease with increasing particle size in the studied range from 92 to 70%. The shale oil produced was distilled in a simple atmospheric distillation unit to give naphtha, gasoline, diesel and residue. The naphtha fraction was found to decrease with increasing particle size. The diesel fraction decreased by 8%, i.e. from 50 to 42%, when particle size was increased from 10 to 40 mm. The kerosine percentage decreased from 35 to 22% with increasing particle size.

Comparison of the yields and structure of fuels derived from freshwater algae (torbanite) and marine algae (El-Lajjun oil shale)

Reactions of a Jordanian El-Lajjun oil shale under N2 or H2 for 1h results in almost complete conversion of the organic material to liquid products at 355°C or 390°C. In contrast, reactions for 1h of the algal coal, torbanite, give minimal conversion at 390°C, but almost total conversion if the reaction time is extended to 5h. At 355°C reactions of torbanite are minimal at 1 and 5h reaction times, however at 425°C for 1h almost complete conversion is observed. In addition, the oil to asphaltene ratio for the products from the Jordanian oil shale increases in the temperature range 355–390°C, whereas the oil to asphaltene ratio for the products from torbanite strongly favours oil at all temperatures.The oil from both materials is highly aliphatic. The torbanite oil is mainly long chain, saturated hydrocarbons with few aromatic compounds. The oil from the Jordanian shale also has a high aliphatic content but a much wider range of aromatics. In addition, significant amounts of sulfur-containing compounds are present.

The Effect of a Solvent System on the Yield and Fractional Composition of Bitumen Extracted From the El-lajjun and Sultani Oil Shale Deposits

Oil shale samples from two oil shale deposits in Jordan (El-lajjun & Sultani) were examined for solvation using different solvent systems, such as chloroform, ethanol, hexane, toluene, and a mixture of chloroform-ethanol. Aliphatic, aromatic, asphaltenes, and nitrogen, sulfur, oxygen (NSO)-containing fractions were separated from the obtained extract. The 1H-NMR and FT-IR spectrum of bitumen extract shows the presence of saturated and unsaturated hydrocarbons. The quantity of these fractions are affected by the polarity and the structure of the solvent. The yield of bitumen from both deposits has a limited value and does not exceed 3 wt%. Samples from Sultani show an increase in extracted bitumen yield compared with El-lajjun.

VARIABLE REACTION ORDER FOR KINETIC MODELING OF OIL SHALE PYROLYSIS

This work investigates kinetics of El-Lajjun oil shale pyrolysis. The kinetic data obtained from TG/DGA curves at heating rates 1, 3, 5, 10 and 30 °Cmin to a final pyrolysis temperature 550 °C were employed assuming their second-order kinetics to determine apparent activation energy, 99– 141.4 kJ/mol and frequency factor, 1.89·10 to 1.71·10, for each heating rate using the Coats & Redfern method. The obtained values of apparent activation energies and frequency factor were modified through an equation to 112–179 kJ/mol and 3.95·10–3.66·10, respectively, to fit the developed kinetic equation. In this study, kinetic modeling of the pyrolysis process was performed using a newly developed variable reaction order. The variable reaction order was inferred directly from the experimental data and correlated with heating rate,

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

Oil shale samples were pyrolysed at different heating rates. The effect of heating rate on fractional composition of shale oil is investigated in 0.2–6 °C min −1 range. It is found that increasing the heating rate increases the content of aliphatic of the liquid shale oil. Normal paraffins of (C 10–C 32) are identified in aliphatic fraction. The maximum concentration of these paraffin is found to be 9.9 wt% at heating rate of 2.5 °C min −1. Hydrogen and sulfur contents of the produced shale oil increase with increasing the carbon weight percent. In the studied heating range 0.2–6 °C min −1, the H/C is not affected. Sulfur weight percent of liquid shale oil is not significantly affected by increasing the heating rate. Increasing the heating rate increases the content of aliphatic of the liquid oil shale and decreases the aromatic fraction. GC–MS analysis indicated presence of saturated and unsaturated hydrocarbons in paraffinic fraction.

Kinetic modeling of liquid generation from oil shale in fixed bed retort

Abstract Kinetics of shale oil generation in a fixed bed retort is modeled using a second order rate equation. Samples from Ellajjun oil shale deposits are tested in 350–550 °C temperatures range. In each run, 400 g are charged to reactor and heated in a range of 2.2–10 °C min −1 . Shale oil liquid is condensed at 0 ± 2 °C and its rate measured as function of time and temperature. Increasing heating rate from 2.2 to 10 °C min −1 decreased activation energy from 115 to 71.2 kJ mol −1 and frequency factor from 2.85 × 10 7 to 9.0 × 10 3 correspondingly. The generated data are modeled using Coats and Redfern differential and integral models. Good agreement has been obtained.

Oil shale pyrolysis kinetics and variable activation energy principle

A modified first order kinetic equation with variable activation energy is employed to model the total weight loss of Ellajjun oil shale samples. Fixed bed retort with 400 g of oil shale sample size is used in this study in 350–550 °C temperature range. Variable heating rate, h, in the range 2.6–5 °C min −1 are tested. Activation energy was allowed to vary as a function of oil shale conversion. The value of the activation energy increased from 98 to 120 kJ mol −1 while the corresponding frequency factor changed from 9.51 × 10 5 to 1.16 × 10 6. Fischer Assay analysis of the studied samples indicated 12.2 wt.% oil content. The oil shale decomposition ranged from 3.2% to 28.0%. The obtained kinetic data are modeled using variable heating rate, pyrolysis temperature and variable activation energy principle in a nitrogen sweeping medium. Good fit to the obtained experimental data is achieved.

Kinetics of hydrocarbon extraction from oil shale using biosurfactant producing bacteria

This study was done to extract hydrocarbon compounds from El-Lajjun oil shale using biosurfactant produced from two strains Rhodococcus erythropolis and Rhodococcus ruber. The results have shown that, optimal biosurfactant production was found using naphthalene and diesel as a carbon source for R. erthropolis and R. ruber, respectively. Optimum nitrogen concentration was 9 g/l and 7 g/l for R. erthropolis and R. ruber, respectively. Optimum K 2HPO 4 to KH 2PO 4 ratio, temperature, pH, and agitation speeds were 2:1, 37 °C, 7 and 200 rpm. Under optimal conditions R. erthropolis and R. ruber produced 5.67 and 6.9 g/l biosurfactant, respectively. Maximum recovery of oil achieved with hydrogen peroxide pre-treatment was 25% and 26% at biosurfactant concentration of 8 g/l and 4 g/l for R. erthropolis and R. ruber, respectively. The extent desorption of hydrocarbons from the pre-treated oil shale by biosurfactant were inversely related to the concentration of high molecular weight hydrocarbons, asphaltenes compounds. Pre- treatment of oil shale with hydrogen peroxide produced better improvement in aromatic compounds extraction in comparison with improvement which resulted from demineralization of the oil shale.

Solvent Extraction of Bitumen from Jordan Oil Shale Assisted by Low Frequency Ultrasound

In this work, the efficiency of 20 kHz frequency ultrasounds versus the classical stirring procedure was investigated on the solvent extraction of Jordanian El-Lajjun oil shale by employing a horn type sonicator. The influence of sonication parameters (sonication time and ultrasonic power) and extraction parameters (extraction solvent and oil shale particle size) on the solubilization of organic matter (bitumen) from oil shale are reported here. The influence of seven individual solvents, namely: tetrahydrofuran, benzene, carbon tetrachloride, chloroform, kerosene, toluene, acetone and a mixture of methanol-acetone-chloroform on the fraction extracted was investigated and it was found that the fraction extracted was 90% after only ten minutes of sonication at 33 W when tetrahydrofuran was used as extraction solvent. It was found that the fraction extracted percentage is strongly influenced by the solvent extraction, ultrasonic power and exposure time and less influenced by the particle size. Under the current experimental conditions and using the tetrahydrofuran as extraction solvent, the extraction time was decreased by four folds while the fraction extracted percentage (E%) was increased by three times.

AN INVESTIGATION INTO BENEFICIATION OF JORDANIAN EL-LAJJUN OIL SHALE BY FROTH FLOATATION

Oil shale is available in Jordan in large quantities with high proportion of minerals. This study presents an investigation in order to enhance oil recovery from Jordanian El-Lajjun oil shale, which represents a major local deposit area. This enhancement was attempted through decreasing the content of minerals by the method of froth floatation using different floatation and frothing agents. The effect of the type of agents, the concentrations of these agents, and the effect of particle size were also investigated. Jordanian El-Lajjun oil shale has shown a poor separation propensity (floatability). Particle size and type of frother did not have any impact on the efficiency of oil shale recovery. A maximum recovery of 3% was achieved when using fuel oil as a collector and methyl isobutyl carbinol (MIBC) as a frother in the froth floatation process. It is believed that kerogen causes wetability of oil shale particles during preparation of oil shale hindering floatability of oil shale. On the other hand, phosphates and calcite were found to be easily separable from Jordanian oil shale using froth floatation. A degree of separation of more than 99% has been achieved when using kerosene as a collector and MIBC as a frother.

COMPARISON OF OIL SHALES FROM DIFFERENT DEPOSITS: OIL SHALE PYROLYSIS AND CO-PYROLYSIS WITH ASH

This paper studies the effect of alkaline oil shale ash on oil shale thermal decomposition products during oil shale and ash co-retorting. Experiments with and without ash were carried out in a standard laboratory-scale retort (Fischer Assay) to determine relative yields of retorting products and sulfur distribution in them. Oil shales compared in this study were kukersite and Dictyonema shales from Estonia, Jordanian El-Lajjun oil shale and Saveljev oil shale from Russia. Oil shales were primarily selected due their difference in sulfur composition. Ash for co-retorting experiments was prepared from kukersite oil shale. The ash contains about 57.5 wt.% alkaline compounds CaO and MgO.

06/00569 Sulfur distribution in the oil fractions obtained by thermal cracking of Jordanian El-Lajjun oil Shale: Al-Harahsheh, A. et al. Energy, 2005, 30, (15), 2784–2795.

06/00569 Sulfur distribution in the oil fractions obtained by thermal cracking of Jordanian El-Lajjun oil Shale: Al-Harahsheh, A. et al. Energy, 2005, 30, (15), 2784–2795.