Thermogravimetric and composition analysis of Jordanian oil shale

Jordan occupies the eighth place in oil shale reserve in the world. Prospective efforts are directed toward the production of fuel from shale. Analysis of oil shale samples will help in planning for energy strategies. Oil shale samples were collected from Wadi Ash Shallala at Yarmouk Basin. X-ray fluorescence spectrometer and X-ray diffraction showed that calcite is the dominant mineral. Other minerals such as; Kaolinite, quartz, and Fluorapatite, were detected. Thermogravimetric analysis revealed that mass loss is due to organic matter decomposition at 350–550°C and carbonate and silicate decomposition at 650–850°C. Fourier transform infrared analysis revealed the main organic groups.     

Two-dimensional numerical modeling of combustion of Jordanian oil shale

A two-dimensional (2-D) modeling of the burning process of Jordanian oil shale in a circulating fluidized bed (CFB) burner was done in this study. The governing equations of continuity, momentum, energy, mass diffusion, and chemical combustion reactions kinetics were solved numerically using the finite volume method. The numerical solution was carried out using a high-resolution 2-D mesh to account for the solid and gaseous phases, k-ε turbulence, non-premixed combustion, and reacting CFD model with the same dimensions and materials of the experimental combustion burner used in this work. The temperature distribution and evolution of species were also computed.

Proximate and ultimate analyses were also performed to evaluate the air–fuel ratio and ash content. The required thermophysical properties, such as heating value, density, and porosity were obtained experimentally, while the activation energy was obtained from published literature.

It was found that the temperature contours of the combustion process showed that the adiabatic flame temperature was 1080 K in a vertical burner, while the obtained experimental results of maximum temperature at various locations of the burner in actual, non-adiabatic, non-stoichiometric combustion reached 950 K, showing good agreement with the model.     

Conversion of oil shale to liquid hydrocarbons

Oil shale is a complex fossil material that is composed of organic matter and mineral matrix. The thermal decomposition of the organic matter generates liquid and gaseous products. Oil shale is a porous rock containing kerogen, an organic bituminous material. Kerogen is a solid mixture of organic compounds that is found in certain sedimentary rocks. The kerogen can be pyrolyzed and distilled into petroleum-like oil. Oil shale and bituminous materials are suitable for obtaining petroleum-like products. The process designed in this study has the ability to control unwanted volatile materials. The mineral matter is removed from oil shale before pyrolysis. The pyrolysis of the oil shale is performed in a retort. The temperature at which the kerogen decomposes into usable hydrocarbons begins at 300°C, but the decomposition proceeds more rapidly and completely at higher temperatures. Decomposition takes place most quickly at a temperature between 475 and 525°C. Shale oil from oil shale consists of the hydrocarbons: paraffins, olefins, isoparaffins and naphthenes, isoolefins and cycloolefins, monocyclic aromatics, and poly-cyclic aromatics. The nonhydrocarbons are nitrogen, sulfur, and oxygen (NSO) compounds.     

Accelerated production and analysis of biofuel derived from photobioreactor engineered microalgae using super critical fluid extraction

This research reports cultivation of microalgae (Chlorella vulgaris) in a locally designed and fabricated closed tubular photo bioreactor and the subsequent extraction using super critical fluid extraction. Microalgae oil yield at various temperatures and pressures is reported. The algal oil is then transesterified into biodiesel using an in-house developed new heterogeneous catalyst. The process eliminates the undesirable saponification, apart from increasing the yield, reducing the reaction temperature, and substantially increasing reaction rate, thus providing the basis for benefiting the biofuel production economy directly. The biodiesel produced using the proprietary catalyst is then characterized by using analytical techniques like gas chromatography/mass spectrometry and nuclear magnetic resonance.     

Utilization of grinding aids in oil shale milling

Grinding aids (GAs) effectively reduce the energy requirements of the grinding process and improve grinding productivity. Two GAs (sodium silicate and triethanolamine (TEA)) were selected and their mechanisms of action were explored. The effect of the different grinding parameters on oil shale grinding efficiency was determined. The adsorption characteristics of the GAs were investigated using scanning electron microscopy (SEM), pulp viscosity, surface potential, and Fourier transform infra-red spectroscopy (FTIR). The results indicate that compared to grinding without GAs, the addition of sodium silicate and triethanolamine (TEA), increases the yield of ?0.075 mm particles by ?2.97% and 14.05%, respectively. The optimal grinding parameters were determined for a pulp concentration 40%, a steel ball weight ratio of Φ32 mm: Φ25 mm: Φ22 mm: Φ18 mm (50:24:17:9), and a grinding time of 20 min. The flotation test results indicate that compared to sodium silicate, TEA is the more suitable GA. The addition of sodium silicate reduced the sharp edges of the particles, increased the pulp viscosity and reduced the surface potential. It was not conducive to pulp dispersion. Conversely, TEA reduced the pulp viscosity and increased the surface potential, which enhanced the repulsive force between the particles, increasing the particle spacing, and the dispersion of the pulp. Sodium silicate and TEA both formed hydrogen bonds or chemical bonds on the surface of the mineral particles, strengthened the steric-hinderance effect, and enhanced the repulsive force between the particles.     

桦甸油页岩燃烧性能的热分析研究

利用热重分析仪在非等温条件下对桦甸油页岩进行了燃烧试验。考察了粒径、升温速率、样品种类等因素对油页岩燃烧特性的影响。采用积分法（C-R法）获得了油页岩的燃烧动力学参数。结果表明，油页岩的燃烧性能随着其挥发分含量的增大而变好，且在燃烧过程中油页岩的表现活化能变化很大，对于不同的燃烧温度范围可用不同的反应级数来描述，在燃烧前期反应级数为1级，而燃烧后期反应级数为3．5级。     

Mineralogical characterization and washability of Longkou oil shale

In order to better understand the mineralogical characterization of various density fractions of Longkou oil shale, float and sink tests were carried out to separate the raw oil shale samples into a series of fractions according to density, firstly. The mineralogical characterization of oil shale was investigated using the analytical methods of X-ray fluorescence spectrometer (XRF), X-ray diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS), and optical microscopy. Density distribution of Longkou oil shale indicated the ash content of oil shale with different density fractions increased with the increase of density fraction. The inorganic minerals composition of oil shale was mainly quartz, kaolinite, montmorillonite, calcite, analcime, dolomite, and pyrite. A comprehensive considering of the results of XRF, XRD, and optical microscopy of Longkou oil shale in each density fraction indicated there was a high content of kerogen in the low-density fraction of the oil shale. So beneficiation of kerogen from raw oil shale may be realized using the gravity separation method.     

Effect of mineralogical composition and kerogen content on oil shale natural floatability

Mineralogical composition is one of the important factors that affect the performance of separation processes. In the current study, two oil shale samples, from El-Nakhil and El-Bieda localities, differ in their mineralogical composition, were subjected to flotation tests. Chemical analysis, differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), and microscopic examination are among the used characterization techniques. In addition, their responses for upgrading by flotation were conducted as a function of pH, solid-liquid ratio, stirring speed and different particle sizes. The characterization results indicated that the kerogen content in El-Nakhil sample was 30% while in El-Beida sample was 10%. On the other hand, the flotation results indicated that El-Bieda responses better than that of El-Nakhil in terms of the difference in kerogen % between the original sample and the concentrated ones. The difference in flotation results of two samples can be explained by the difference in kerogen morphology as well as its interaction with surrounding matrix. In El-Bieda the kerogen has a laminated structure but in El-Nakhil it appears as laminated liptinitic component, in addition to the higher carbonate content in El-Nakhil sample in comparison to higher clay content in El-Bieda sample.     

The effect of acid treatment on pyrolysis of Longkou oil shale

The effect of acid treatment on mineral removal and pyrolysis of Longkou oil shale were investigated. X-ray diffraction (XRD) and X-ray fluorescence (XRF) indicated that the HCl treatment can remove the calcite, the H₂SO₄ treatment can convert the calcite to CaSO₄, and the HF treatment can remove the quartz and convert the calcite to CaF₂; moreover, all three treatments cannot remove the pyrite in the oil shale. Oil shale was individually treated with HCl, H₂SO₄, and HF before conducted the pyrolysis experiment. The pyrolysis results showed that oil shale treated with H₂SO₄ or HF almost equally enhanced the oil yield, while HCl treatment had a negative effect on the oil yield. Thermogravimetry (TG) analysis indicated that the carbonates had a catalytic effect, sulfates may also had a catalytic effect and the silicates had an inhibitive effect on the decomposition of kerogen. Combining the TG analysis, oil yield and the price of every acid, the H₂SO₄ treatment was considered to be the best method to treat oil shale.Moreover, the carbonate minerals can be removed after H₂SO₄ treatment, so it would reduce the amount of pyrolysis feed to increase production efficiency.     

Studies of the effect of retorting factors on the yield of shale oil for a new comprehensive utilization technology of oil shale

The comprehensive utilization of oil shale is a new promising technology achieving high utilization-factors for both oil shale’s chemical and energy potentials, and avoiding serious environmental impacts. For this technology, it is an urgent issue how to obtain shale oil with a high yield and as well as treat shale char efficiently and economically. In this present work, retorting experiments of three type I oil shales were performed using an aluminum retort, and the effect of retorting temperature, residence time, particle size and heating rate on the yield of shale oil was studied at low retorting temperatures ranging from 400 °C to 520 °C, respectively, at which shale char obtained has good combustion properties. The experimental data show that an increase in the retorting temperature, the residence time and the heating time has positive significant effect on improving the yield of shale oil, and a middle particle size is helpful for increasing the oil yield as well. The grey system method was applied to evaluate the effect of retorting factors on the yield of shale oil, showing that the retorting temperature is the most marked factor influencing the yield of shale oil.     

Tertiary recycling of waste plastic using catalytic cracking into crude oil

Disposal of waste plastic and excessive use of fossil fuels have caused environmental problems in the world. According to an estimate, more than 100 million tonnes plastics are produced every year and after their usage these plastics are discarded to become waste. Both plastic- and petroleum-derived fuels are hydrocarbons that contain the elements of carbon and hydrogen. The main difference between these hydrocarbons is that plastic molecules have longer carbon chains than those of LPG, petrol and diesel fuels. Therefore, it is possible to convert waste plastic into fuels. Pyrolysis is a prospective method to handle waste plastics. The purpose of this study is to explore the ability of different types of catalysts in conversion of plastic waste to low-emissive hydrocarbon fuel. Pyrolysis experiments were conducted using three different catalysts to check their ability in increasing the production. Catalytic degradation with potato peels yielded 74.52 wt% liquid fuel product. So far, the use of potato peels as a biocatalyst in pyrolysis process has not been reported. The pyrolysis oil was analyzed by GC/MS to determine its elemental composition. The liquid products obtained were compatible with international standards. Therefore, two main global problems such as problem of waste plastic management and problem of shortage of fuel are being tackled together.     

Physiochemical analysis of selected shale formations of Kohat region by advance characterization for oil potential evaluation

The current scientific study summarized the physiochemical analysis of shale sample by advance characterization such as Fourier-transform infrared spectroscopy? (FTIR), X-ray diffraction? (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy? to evaluate the energy potential of shale rock pertinent in Kohat region of Pakistan. The samples were collected during the drilling of mines from 1,670 to 4,500 m depth. A total of 21 samples were collected, among which 14 samples were taken from Patala Formation, 4 were from Panoba formation, and 3 were from Kuldana Formation. The proximate analysis was conducted to determine the gross calorific value, moisture, and volatile matters. SEM confirmed the porous surface of shale samples. XRD analysis revealed the presence of quartz, calcite, and plagioclase in the collected shale samples. FTIR tests were conducted to identify functional groups inside the shale samples. It was observed that Panoba Formation has a considerable amount of hydrocarboneous matters with an average value of 6.25%. Patala Formation got lower hydrocarboneous matters than Panoba with an average value of 5.22%, whereas Kuldana Formation contains a hydrocarboneous average value of 3.51%.

Abbreviations: FTIR: Fourier-transform infrared spectroscopy; XRD: X-ray diffraction; SEM: Scanning electron microscope; EDX: Energy dispersive x-ray spectroscopy; VOC: Volatile organic compound; ASTM: American Society for Testing and Materials.     

The effect of minerals on the pyrolysis and the combustion of oil shale

Oil shale (OS) is a particularly promising alternative fossil fuel source. However, very different from coal, its inorganic mineral content is very high. The organic matters (mainly kerogen) are finely distributed in the inorganic minerals. Therefore, the minerals may affect the processing of OS, whose elucidation is critical to the choice of processing conditions. In this work, different minerals (SiO₂, CaCO₃, and Al₂O₃) were added to OS with different mass ratios of OS to mineral, respectively. Then, the thermogravimetric (TG) technique was employed to analyze the reaction behavior of these different OS/mineral mixtures in N₂ and in air for studying the influence of minerals on the OS pyrolysis in N₂ (i.e., retorting) and on the OS combustion in air. The results show that CaCO₃ and Al₂O₃ have a promoting effect on both pyrolysis and combustion of OS, and they can decrease the reaction activation energy of both kinds of processes. However, SiO₂ has an inhibitive effect and can increase the reaction activation energy for both kinds of processes. It is hoped that the present study can further increase the understanding toward the effect of different minerals on the OS reactions.     

油页岩燃烧反应活化能不同求解方法的比较

利用热重分析仪在非等温条件下测得的桦甸油页岩燃烧试验数据，分别采用Coats-Redfern法和等转化率法（KAS法）对油页岩燃烧反应的表现活化能进行了求取，并对结果进行了比较。结果发现，用两种方法得出的活化能都表明油页岩燃烧分为两个阶段，且燃烧前期的活化能低于燃烧后期；等转化率法分析的结果表明，油页岩燃烧是一个复杂的多步反应过程，而C-R法将反应的机理简单假设为遵循反应级数模型，本身就存在问题，所以其得出的活化能值可靠性不高。     

CO2 gasification characteristics of nascent pyrolyzed particles from coals and oil shale

In this work, the co‐pyrolysis characteristics of oil shale with two typical coals, bitumite and lignite, and the co‐gasification characteristics of the mixture pyrolyzed fuels were studied via thermo‐gravimetric analysis. The individual fuels and mixture fuels were first pyrolysis in N₂ atmosphere to specified temperature (450, 550, and 620 °C) at the heating rate of 20, 30 and 40 °C/min, respectively, and then maintained at the given temperature for 20 min before converted to CO₂ ambient to conduct the CO₂ gasification tests. The kinetic behavior and effects of both fuel types and pyrolysis temperature were investigated. The shoulder peak at around 550 °C observed in the derivative of weight loss derivative thermogravimetry analysis (DTG) curve during the pyrolysis of oil shale has confirmed the existence of specific reactions of oil shale at around 550 °C that leads to a sharp trough in the differential curves of co‐pyrolysis with coals and the unusual change in activation energies of gasification. In isothermal pyrolysis stage, oil shale lost its vast majority of organic matters at the temperature lower than 550 °C. The escape of pyrolysis gas and liquids in the coals is much harder than that in oil shale. The interaction between oil shale and bitumite was too weak to discriminate both in the pyrolysis and CO₂ gasification process. The variation of the particle surface structure caused by the releasing of volatile gases is strongly affected by the reaction rate and temperature. Quick volatile decomposition and gas releasing lead to the increase of surface area, decrease of the average pore diameter as well as the uniformization of the pore structure, while the higher temperature results in the blockade and merging of fine pores. The two factors lead to the greatest mass loss rate in the pyrolyzed particles obtained at 550 °C in temperature programmed CO₂ gasification stage. Two model‐free methods, Friedman method and Flynn–Wall–Ozawa method, were used to extract kinetic parameters from the experimentally determined pyrolyzed fuel conversions. The volatile contend has a significant influence on the fixed carbon conversion during the partially pyrolyzed particles' CO₂ gasification. In this study, significant interactions existed in co‐thermal utilization, both pyrolysis and CO₂ gasification, of oil shale and lignite. It is therefore surmised that co‐gasification of pyrolyzed lignite and oil shale may represent a feasible, practical route to high‐efficiency utilization of these fuels. Copyright © 2017 John Wiley & Sons, Ltd.     

Gravity separation of oil shale and low-temperature pyrolysis characteristics of different density fractions

In this paper, gravity separation of Huadian? (HD) and Longkou? (LK) oil shales and low-temperature pyrolysis characteristics of their different density fractions have been studied. The gravity separation results showed that kerogen could be enriched using the gravity separation method. The low-temperature pyrolysis results showed that the highest oil contents of HD and LK were in the density fractions of 1.4–1.5 and 1.5–1.6 g·cm^?3, respectively. Meanwhile, for the low-temperature pyrolysis, the oil/gas ratio decreased with the density increase, indicating higher gas loss and lower oil yield with the increase of density. The mineralogical analysis showed that most of the organic matter were associated with clay minerals, and the organic matter could not fully liberate from the matrix under coarse particles. The migration and occurrence of minerals and organic matter in different density fractions generated various pyrolysis characteristics.     

特大型热油炉的设计

介绍特大型热油炉的炉型结构,炉排型式以及对流室和辐射室的热负荷分配。     

Effective diffusivity of oxygen in the ash layer of Huadian oil shale semicoke

Diffusion of oxygen in the ash layer usually dominated the combustion of oil shale semicoke particles due to the high ash content. Thus, effective diffusivity of oxygen in the ash layer was a crucial parameter worthy of careful investigation. In this paper, the effective diffusivity of oxygen in the ash layer of Huadian oil shale semicoke was measured directly using an improved Wicke-Kallenbach diffusion apparatus. The experimental results showed that higher temperature would lead to a higher effective diffusivity and a thicker ash layer had the negative effect. Especially, the effective diffusivity along the direction perpendicular to bedding planes was much lower than that along the direction parallel to bedding planes. In addition, an effective diffusivity model was developed, which could be used to describe the mass transfer of oxygen in the ash layer of oil shale semicoke.     

Dust explosion of oil shale and olive cake solid fuels: a comparison study

This paper investigates the inhibition of oil shale and olive cake dust explosions when they are used as an alternative source of fuel. Special emphasis was given to the effect of particle size of the same material on the maximum permissible oxygen concentration to prevent dust explosion for different concentrations using nitrogen as the diluent gas. It was found that olive cake is ignited more easily than oil shale all over the range of particle sizes and dust concentration. Tests on different particle sizes were carried out, and it was found that the maximum permissible oxygen concentration for a given dust concentration increases with increasing the particle size for both oil shale and olive cake. Copyright © 2005 John Wiley & Sons, Ltd.