Energy Sources, Part A, 29:1471–1476, 2007 Copyright © Taylor & Francis Group, LLC ISSN: 1556-7036 print/1556-7230 online DOI: 10.1080/00908310600626523
Combined Process of Solvent Extraction and Gamma-Ray Radiation for the Extraction of Oil from Oil Shale M. MATOUQ O. ALAYED Al-Balqa Applied University Faculty of Engineering Technology Chemical Engineering Department Amman, Jordan Abstract Jordanian oil shale kerogen was studied by using several solvents under the gamma radiation condition to extract oil from shale. According to the result obtained, the possibility to extract oil at room temperature and using solvent was successfully obtained. The solvent used in this research study was water, benzene, acetone and kerosene. Experiments was conducted by using a mixture of solvents such acetone water, benzene-acetone, benzene-kerosene, and benzene, kerosene, water alone without mixing. The percentage of yield was found to be with in the range of 13–67. The result showed that acetone-water solvent mixture with 50% of each (vol%) gives the best results. In this study, the particle size was fixed at 1mm size since there was no effect size on extraction yield percentage. Keywords energy resources, gamma radiation, oil shale, radiation, solvent extraction
Introduction Oil shale is a material with hydrogen content between that of coal and crude oil due to the fact that it was never buried deeply enough or heated enough to form crude oil. The concentration of oil in this material is quite low, and it is chemically bonded to the shale. The maximum amount of recoverable oil is one barrel per 2.4 tons of sand or 1.5 tons of rock (Bseisso, 1998). Enormous environmental problems also occur with extraction of oil from oil shale. The potential amount of oil contained in oil shale is greater than the known and unproved crude oil resources in the world, which would add approximately 40 years to the projected time before oil will be exhausted. The dilemma is that it takes about half the energy contained in the shale to extract the oil. Prices for barrels of oil from oil shale can range from $40 to $80 per barrel. However, Mitsubishi cooperation in 1995 has revealed by a local study that a pilot plant with the capacity of 20,000 bbl/day will cost 17$/bbl (Japan National oil cooperation, 1995). Recently, and as the oil prices are Address correspondence to Mohammed Matouq, Al Balqa Applied University, Faculty of Engineering Technology, Chemical Engineering Department, P.O. Box 4486, Amman 11131, Jordan. E-mail:
[email protected] or
[email protected]
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getting higher and higher (40–50$/bbl) after the Gulf War, the processing of oil shale is a promising alternative of exported oil to Jordan. Oil can be utilized from shale by either direct combustion or retorting; several experimental have been conducted in Jordan in this field (Bsieso, 2003). In direct combustion process, after crushing the whole rock of oilshale, and as the oil content is quite enough to give a self-sustain ignitions and be used as source of energy. In retorting process, part of the oilshale can be burned and be used to extract oil at high temperature and the volatile light oil can be recovered as distillate after cooling (Khraisha, 2000). The factor determinant here is energy cost and pollution impact of direct combustion. Guo (2000b) has treated Jordanian oil shale by solvent extraction with chloroform and two mixed solvents—methanol/acetone/chloroform (M/A/C) and CS2/N-methyl-2pyrrolidinone (CS2/NMP). It was found that the extraction yield and the composition of the extracts are quite different in the case of different solvents. In Jordan the National Energy Research Center studied the solvent extraction using benzene, cyclohexane, chloroform, xylene, ethanol, carbon disulfide, and toluene the result has revealed that carbon disulfide has the best ability to dissolve the kerogen while others was able to do so, but ethanol was the lowest one and has even gave a zero value for solubility (NERC, 1999). It now has been established that the solvent extraction methods is one of the most promising techniques for utilization of oil, and hundreds of solvents were tested to different oil shale in the world (Tamimi and Abdel-salam, 1990; Tamimi and Uysul, 1990; Guo, 2000a). In this research, a comparison study between using solvent extraction combined with gamma radiation with conventional solvent extraction methods was investigated. Using the gamma ray technique will help in reducing the environmental impact of utilizing the oil shale by either direct combustion or retorting. Introducing Gamma ray radiation will enhance the penetration of solvent inside shale. Another advantage of using this technique is that no need to use any source of heat as extraction can be occurred at room temperature and no mixing procedure will be needed and hence will reduce the energy consumption. The use of Gamma ray for scientific research will enhance and promote the peaceful use of radioactive compound.
Experimental Setup Gamma Irradiation Facility The pilot-scale gamma-irradiation facility (PX- -30 ISSLEDOVATELJ) utilizing Co-60 radiation sources is used for this experiment. The device is fully operated and controlled by the Ministry of Energy and Mineral Resource of Jordan (MEMR). The maximum activity of radionuclide in source 24 kilo Curie (kCi). The maximum dose rate in center of working chamber is 1.6–1.9 106 r/h. The irradiation is 8,386 Curie. The size of the irradiation chamber is cylindrical with 160 mm diameter and 220 mm height (44,000 cm3 ); it is surrounded by walls made of 1.7 m normal concrete. Safe entrance to the irradiation chamber is ensured by a shielded maze with several turnings (breaks). The entrance door of the maze is made of steel. Access of personnel and transport of products are controlled by safety rules and technology to prevent accidental exposure of personnel or visitors. The irradiation process can be monitored from the control desk in the control room adjacent to the irradiation chamber. The irradiator is operated fully automatically, controlled by an electronic control unit. Irradiation during daytime-operation is performed in the presence of operators by manual or automatic control.
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Table 1 The sample of oil and its content analyzed by MENR Total water, wt%
Gas loss, wt%
Spent shale, wt%
Oil content, wt%
3.0
7.4
78.6
11.0
Research Methodology One size of oil shale 1mm, obtained from ministry of energy and mineral resources (MEMR). The composition of the oil shale was analyzed by Natural Resources Authority of the Hashemite Kingdom of Jordan (NRA), and is given in Table 1. The dose of gamma ray was fixed at 5 kgray/hr for 72 h at 20ı C.
Procedure 100 g of oil shale of size 1 mm placed in 250 ml of a mixture of benzene, water, kerosene, and acetone with fixed percentage of mixing portions. Table 2 shows the condition and solvents mixtures used in this experiment. Without any further processing, the sample placed inside gamma ray apparatus exposed to the ray for 72 h. Analysis and Sample Procedure The mixture of solvent and oils was placed on gamma ray device and kept for 72 h. The sample was then removed and simply filtered by using 40 grade Whatt paper. Two ml of sample was taken by syringe from the mixture with its oil content (can easily detected by eye with its dark brown color and viscous) and placed at 70ıC oven under nitrogen gas circulation. The sample was kept for 24 h. When the solvent was completely dried, the sample weighted and this result was compared with the original oil content in the sample.
Table 2 Solvents and mixture of solvents used to extract oil at 20ı C Solvent
Percentage of mixing and solvent’s name, vol%
Sample number
Acetone Acetone water Benzene Kerosene Benzene kerosene Benzene acetone
100% acetone 50% acetone, 50% water 100% 100% 50% benzene, 50% kerosene 50% benzene 50% acetone
A12 AW12 B12 K12 BK12 AB12
All experiments were conducted at fixing oil shale weight at 10 g, and solvent at 20 g.
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Results and Discussion As is shown in Figure 1, the mixture of benzene and acetone (BA, each 50% by volume) gives the highest quantity of oil extracted from oil shale. The acetone water solvent (AW, each 50% by volume) showed the second rank of extraction. However, still water and acetone alone without mixing showed lower power on extraction compared to a mixture of both solvents. This means the combination of both solvents gives the higher extraction yield. Figure 1 reveals that although kerosene gives a high amount of oil, this is due to the fact that kerosene at this experimental conditions and analysis procedure could not be evaporated totally at 70ıC. Even the sample was kept longer to assure evaporation, but no complete drying was observed. It was difficult to rise the temperature higher than 70ıC, so that the light compounds exist inside extracted oil also evaporated. Therefore, this has increased the value of (oilCkerosene, and kerosene alone) yield value. In this case, the analysis procedure shall be considered here when kerosene is used and another procedure shall be taken. It is also interesting that water alone as solvent is not preferable over benzene but it has a power of extraction to remove oil from shale. This is an interesting result since it has approved with experiment that water alone at normal condition has no ability to remove any amount of oil, while under radiation the result is completely different. There is no contradiction between the combination of solvent after mixing on yield capacity. For example, water alone has the least effect on yield compared to benzene and acetone. The same behavior had been noticed after mixing benzene, acetone and water as solvents. However, it is noticed that when water was added to other solvents as a mixture, it reduced the capacity of extraction. Benzene acetone mixed solvent showed the best combination for solvent mixture over acetone water mixed solvent. The effect of solvent on yield of extracted oil is shown in Figure 2. The yield is higher when a mixture of solvent was used and lower when no mixing with solvent was used. This means in the case of solvent extraction it is better to use two miscible
Figure 1. Amount of extracted oil from oil shale for different solvents after gamma radiation exposure for 72 h at room temperature and no mixing.
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Figure 2. Type of solvent and its effect of yield percentage of oil extracted.
mixtures for solvent extraction. The power of extraction on oil shale with and without solvent mixing is following this pattern Benzene
Acetone > Acetone
Water > Acetone > Benzene > Water:
The mixture of benzene acetone gives the highest yield of 71% while water alone gives the lowest yield of 13%. Again, the kerosene gives high value due to the fact that it could not evaporated at this experimental condition, but this shall not be considered as the best solvent. To ensure that the effect of solvent on the separation a blank sample with 10 g and 1 mm particle size of oil shale fixed in 100 ml flask. The flask placed inside the gamma irradiation device with the same experimental conditions with no solvent. It was assured that no oil extracted or precipitated inside the flask after radiation. This means that without solvent there will be no separations of oil.
Conclusion The extraction of oil from oil shale has been conducted successfully at room temperature without any mechanical mixing source, using cheap solvent extraction and simple techniques. This will lead to the conclusion that using gamma ray radiation will be a promising technique to extract oil from oil shale with less effort compared to the conventional methods of solvent extraction. There is a significant effect of gamma ray on oil shale so that it made the extraction process easier, and this phenomenon needs to be explored in more detail to study the mechanisms of oil removal from the shale itself.
Acknowledgments The author is grateful to the Ministry of Energy and Mineral Resources of Hashemite Kingdom of Jordan for giving the permission of using the gamma ray and supplying the samples of oilshale materials. The author is extending his thanks to Natural Resources Authority of the Hashemite Kingdom of Jordan for analyzing the data and the technical supports.
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References Bseisso, M. 1998. Utilization of Jordanian oilshale by direct combustion and retorting. Ministry of Energy and Mineral Resources. Bsieso, M. S. 2003. Jordan’s experience in oil shale studies employing different technologies. Oil Shale 20:360–370. Guo, S. 2000a. Solubility of Maoming oilshale Kerogen. Oilshale J. 17:1116. Guo, S. 2000b. Solvent extraction of Jordanian oil shale kerogen. Oilshale J. 17:266–270. Japan National Oil Cooperation. 1995. Economical Evaluation of Oil Shale Deposits with Oil Content. Tokyo, Japan. Khraisha, Y. H. 2000. Retorting of oil shale followed by solvent extraction of spent shale: Experiment and kinetic analysis. Energy Sources 22:347–355. NERC: National Energy Research Center. 1999. Extraction of Organic Compounds from the Oil Shale using Soxhlet Extractor, Jordan. Tamimi, A., and Abdel-salam, O. 1990. Washing the extraction of El-Lajjun oilshale deposit with a mixture of organic solvents. Sep. Sci. and Tech. 25:1141–1151. Tammi, A., and Uysul, B. 1990. Parametric investigation of oilshale extraction with organic solvent. Sep. Sci. and Tech. 25:1151–1159.
