Combustion performance and kinetics of oil shales

In this research, combustion performance and kinetics of two Turkish oil shales were investigated using differential scanning calorimetry (DSC), thermogravimetry (TGA/DTG), and thermogravimetry–mass spectrophotometry (TG–MS) techniques at three different heating rates (10, 30, and 50°C/min). The combustion reaction occurred in two different regions and the corresponding mass loss of oil shales was calculated. Activation energies of oil shale samples are calculated using three different methods and the results are discussed from the viewpoint of the origin and grade of the samples.     

Evaluation of oil yield from Jordanian oil shales

In this paper, the influences of particle size, grade and pyrolysis temperature on the oil yield have been evaluated in a laboratory scale reactor. Five categories of particle sizes from two different oil shale samples were pyrolyzed by employing a fixed bed retorting system. The reactor and the oil shale sample were heated at a constant rate and nitrogen gas was used to purge the sample, continuously, in order to remove the pyrolysis products from the reactor as well as to reduce secondary reactions. The liquid products were condensed and collected in a series of cold glass-traps and the off-gases analysed for their hydrocarbon and non-hydrocarbon species. Subsequent experiments were carried out, employing a thermogravimetric analyser, using only the four smallest particle sizes under similar conditions as applied to the fixed bed retort. The activation energy was determined by using the integral method. The pyrolysis of the investigated shales was found to comply with first-order kinetics within the limits of experimental error. Increasing the particle size resulted in a small rise in the liquid oil yield, but simultaneously the total gaseous production was decreased.     

Combustion kinetics of oil shales by thermogravimetric analysis

This study investigates the combustion characteristics of oil shales obtained from two different regions and their blends prepared by mixing them in the proportions of 25, 50, and 75%. To this end, thermogravimetric analyses were performed at an air atmosphere flow rate of 100 ml/min and heating rates of 5, 10, 40°C/min. The kinetic parameters of combustion reaction were calculated using the Coats&Redfern kinetic model.     

Thermal and geochemical structure of the Uenotai geothermal system, Japan

The Uenotai geothermal area is located in southern Akita prefecture of northern Honshu Island. The Uenotai geothermal system is a liquid-dominated system with a central zone of aquifer boiling. The two-phase reservoir has evolved from liquid in the natural state due to exploitation. Gas composition of the vapor phase in the reservoir is nearly in equilibrium and correlates with the vapor fraction in the reservoir and with discharging steam quality. The marginal part of the Uenotai system has cooled with the drop in ground-water level. The chemical characteristics of the geothermal water indicate mixing of the immature high Cl source water with conductively heated or steam-heated shallow water or surface water, as well as boiling and steam gain.     

Reaction kinetics of fluidised bed gasification of Jordanian oil shales

Trying to achieve the optimal utilisation of oil shale resources, and the production of a more environmentally acceptable fuel, as well as a solid waste with a low a sulphur content, thereby reducing acidic leachates, has led to this investigation. In this article, the influences of the bed temperature and the choice of fluidising gas on the quality and quantity of the produced fuel gas, using a continuous feed fluidised bed reactor, were investigated. The composition and calorific value of the generated gas were determined. There was a nearly linear increase in the amount of fuel gas produced as a function of temperature, reaching ∼350 kg per 10³ kg of dry raw shale and the gross calorific value ranged from 15 to 23 MJ·kg⁻¹ with CO and H₂ being the major constituents. Subsequent experiments were carried out, employing a thermogravimetric analyser under similar conditions as applied to the fluidised bed reactor. Gasification of the investigated shales complied with first-order kinetics within the limits of experimental error and the activation energy and temperature at which maximum reactivity rate occurred decreased slightly as the shale particle size was reduced.     

Energy self-sufficiency of smallholder oil palm processing in Nigeria

The study evaluated the contribution of various energy sources to the smallholder processing of oil palm in Nigeria. Ten small-scale palm oil processing mills were visited at Elele, River State, Nigeria for sample collection. The weight of the various solid wastes generated and utilized for boiling process were measured including EFB (empty fruit bunch), PPF (palm press fiber), PKS (palm kernel shell) and chaff, while the volume of diesel used for digestion was also measured. The processing of 1 tonne of FFB (fresh fruit bunch) in the mill yields 63.4–77.1 L of CPO while the following waste by-products were generated from the FFB; 24 to 31% EFB, 23 to 28% PPF, 10 to 12% PKS and 1.4 to 2.4% chaff. Out of the total biomass generated by the mills only 12.74–22.25% EFB, 24.43–33.38% PPF, 2.71–6.71% PKS and 15.12–49.04% chaff were utilized by the various mills for fruit boiling/sterilization, indicating that the majority of biomass wastes is unutilized in the mills. The volume of diesel utilized by the mills for digestion is quite low ranging from 0.6 to 0.8 L. The gross calorific values of the waste biomass are EFB 16.970–18.537 MJ/kg, PPF 16.472–21.037 MJ/kg and PKS 19.378–21.614 MJ/kg. The total energy utilized by the mills for processing 1 tonne of FFB ranged from 2179.43 to 3014.31 MJ. Out of these, biomass energy accounted for 98.22–98.75%, while fossil fuel accounted for the remaining 1.25–1.78%. The study concluded by suggesting innovative ways of substituting the <2% fossil fuel contribution with the direct use of pre-heated palm oil to fuel the digesters.     

The geochemical characterization of crude oils reservoired in Cretaceous sequences,Lower Indus Basin,Pakistan

Geochemical analyses of the 10 crude oils from Cretaceous sequences, Lower Indus Basin, Pakistan, are performed to characterize source, depositional environment, biodegradation, and thermal maturity to establish genetic relationship. Low sulfur, high pristane/phytane (Pr/Ph) ratios, and high American Petroleum Institute gravity indicate oxic depositional environment and terreginous input of organic matter (OM). Full suite of n-alkanes, low isoprenoid/n-alkane ratios, elevated saturates/aromatics ratios, and the absence of unresolved complex mixture indicate typical non-biodegraded light crude oils. The carbon preference index, odd even predominance, Pr/n-C₁₇, and Ph/n-C₁₈ ratios reveal that source rocks generating Lower Indus Basin crude oils are thermally mature. Based on geochemical analyses, the source OM input is probably terreginous mixed with marine, deposited under suboxic to oxic depositional environments.     

Local involvement in harnessing crude oil and natural gas in Nigeria

Vast financial investments have been made in the upstream crude-oil and natural-gas (CONG) sector in Nigeria, but have not resulted in significant benefits for most Nigerians. The associated major activities, e.g., exploration, drilling, production, well intervention and service provision remain primarily controlled and managed by foreign multi-national companies. Only minor contracts have been awarded to local contractors. Several factors, ranging from locally inadequate finance being available, corrupt local operators, lack of technical expertise and the conflicting attitudes of multi-national operators and local contractors have contributed to this. Yet, numerous opportunities are increasingly available for indigenous entrepreneurs and local contractors. To achieve good public relations, sustainability and better economic performances, a wiser balance between globalisation and localisation is needed! This study considers the impedances to achieving greater indigenous inputs to the CONG sector, with recommendations proffered with respect to what could be done to alleviate them.     

The geochemistry of trace elements in marine oil shales and their combustion residues: Occurrence and environmental aspects

With the aim of better understanding geochemistry of trace elements in marine oil shale and its combustion residues, 23 raw samples, 17 oil shale combustion residues, and 18 selected minerals from Bilong Co oil shale are studied. Potentially hazardous trace elements in raw samples include As, B, Cd, Mo, and Se, while Se, Mo, Cd, As, Bi, and U are potentially hazardous trace elements in combustion residues. As is controlled mainly by Fe-bearing minerals. B occurs mainly in clay minerals. Cd is enriched mainly in calcite. Mo is controlled mainly by organic matter. Se is mainly controlled by P-bearing minerals.     

Impact of oil price shocks on selected macroeconomic variables in Nigeria

The impact of oil price shocks on the macroeconomy has received a great deal of attention since the 1970 s. Initially, many empirical studies found a significant negative effect between oil price shocks and GDP but more recently, empirical studies have reported an insignificant relationship between oil shocks and the macroeconomy. A key feature of existing research is that it applies predominantly to advanced, oil-importing countries. For oil-exporting countries, different conclusions are expected but this can only be ascertained empirically. This study conducts an empirical analysis of the effects of oil price shocks on a developing country oil-exporter—Nigeria. Our findings showed that oil price shocks do not have a major impact on most macroeconomic variables in Nigeria. The results of the Granger-causality tests, impulse response functions, and variance decomposition analysis all showed that different measures of linear and positive oil shocks have not caused output, government expenditure, inflation, and the real exchange rate. The tests support the existence of asymmetric effects of oil price shocks because we find that negative oil shocks significantly cause output and the real exchange rate.     

Shallow submarine and subaerial, low-enthalpy hydrothermal manifestations in Punta Banda, Baja California, Mexico: Geophysical and geochemical characterization

The low-enthalpy geothermal system at Punta Banda (NW Baja California Peninsula, Mexico) has been studied because it might provide heat to future desalination plants in the city of Ensenada. Utilization of subaerial, intertidal and submarine hot springs is evaluated based on geochemical and geophysical data. The results of the geochemical studies show that the geothermal fluids have a major meteoric water component because seawater is not present at the subaerial springs and hot wells. The highest estimated reservoir temperature (140 °C) calculated using a silica geothermometer corresponds to the Agua Caliente intertidal manifestation, a promising area also identified by geophysics. Geothermometric calculations applied to the computed composition of the thermal end member yield a reservoir temperature of 137 °C. Cl/B ratios indicate that the thermal fluids discharged by the intertidal vents and subaerial springs are similar, but they differ from those of submarine vents. Geoelectrical models depict an anomalous conductive trend from the La Jolla well to the Agua Caliente manifestation, suggesting the presence of a fault that allows upflow of hot water from depth. Lastly, integration of geochemical and geophysical data identified the best site for future exploration drilling at Punta Banda.     

Thermal decomposition behavior,characterization and evaluation of pyrolysis products of agricultural wastes

Thermal decomposition behavior during pyrolysis, the composition and the physicochemical characteristics of the pyrolysis products were studied for four agricultural wastes from Southern Greece. These wastes are produced in abundance in the Mediterranean Region but still remain relatively unexploited, while there is also lack or little relevant scientific information. Pyrolysis process for the examined samples was studied using a TGA analyzer and a properly tested and calibrated TG/MS setup, at a heating rate of 10 °C/min up to 850 °C. Determination of important quantitative parameters of pyrolysis as a function of temperature, on an instantaneous or integral basis, and correlation of the evolved gas results with the degradation of pseudocomponents of raw biomass was made possible. The average higher heating value of the pyrolysis light gases was found to be in a satisfactory for energy purposes range of 11.2–14.4 MJ/Nm³. Furthermore, biochars produced at 450, 550 and 650 °C in a fixed bed reactor were found to exhibit calorific value ranging from 20.1 to 28.7 MJ/kg and structural stability. They were also found to have a high nutrients content and below limits or negligible heavy metals content for soils applications, regardless of production temperature.     

Preparation,characterization, engine combustion and emission characteristics of rapeseed oil based hybrid fuels

In this study, hybrid fuels consisting of rapeseed oil/diesel blend, 1% aqueous ethanol and a surfactant (oleic acid/1-butanol mixture) were prepared and tested as a fuel in a direct injection (DI) diesel engine. The main fuel properties such as the density, viscosity and lower heating value (LHV) of these fuels were measured, and the engine performance, combustion and exhaust emissions were investigated and compared with that of diesel fuel. The experimental results showed that the viscosity and density of the hybrid fuels were decreased and close to that of diesel fuel with the increase of ethanol volume fraction up to 30%. The start of combustion was later than that of diesel fuel and the peak cylinder pressure, peak pressure rise rate and peak heat release rate were higher than those of diesel fuel. The brake specific fuel consumption (BSFC) of hybrid fuels was increased with the volume fraction of ethanol and higher than that of diesel. The brake specific energy consumption (BSEC) was almost identical for all test fuels. The smoke emissions were lower than those for diesel fuel at high engine loads, the NO_x emissions were almost similar to those of diesel fuel, but CO and HC emissions were higher, especially at low engine loads.     

Thermal conductivity measurement and characterization of binary nanofluids

Binary nanofluids, nanoparticle suspensions in binary mixture, are developed to enhance the heat and mass transfer performance of absorption refrigeration cycles. To stabilize the nanoparticles in a strong electrolyte, polymer is used as a steric stabilizer. The effective thermal conductivities of the binary nanofluids with the concentrations of nanoparticle up to 0.1 vol% are measured using the transient hot wire method. Comparing the thermal conductivity change with time, it is found that the dispersion stability of nanofluids is a dominant factor for enhancing the thermal conductivity of binary nanofluids. It is also found that the thermal conductivity of the binary nanofluids (H₂O/LiBr binary mixture with Al₂O₃ nanoparticles) increases with the particle volume concentration and enhances by 2.2% at 0.1 vol% concentration condition. Also a modified dimensionless group is proposed to find the maximum radius of nanoparticles to maintain stable nanofluids. In this study, it was estimated ～1.3 μm.     

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.     

Thermoanalytical characterization of castor oil biodiesel

The castor oil seed has 47–49% of oil. Biodiesel obtained from castor oil has a lower cost compared to the ones obtained from other oils, as due its solvability in alcohol transesterification occurs without heating. The use of biodiesel will allow a reduction on the consumption of petroleum-derived fuels minimizing the harmful effects on the environment. This work wants to provide a thermoanalytical and physical-chemistry characterization of castor oil and biodiesel. Biodiesel was obtained with methyl alcohol and characterized through several techniques. Gas chromatography indicated methyl ester content of 97.7%. The volatilization of biodiesel starts and finishes under inferior temperatures than the beginning and final volatilization temperatures of castor oil. Biodiesel data are very close to the volatilization temperatures of conventional diesel.     

Energy use analysis of selected palm-kernel oil mills in south western Nigeria

Energy use patterns and utilisation efficiencies in 40 factories producing palm kernel oil (PKO) in southwestern part of Nigeria were studied. The factories were stratified into small, medium and large scale categories based on the mode of operations and production capacities. Questionnaires were administered on the factories to obtain historical data on petrol, diesel and electricity consumption and PKO production outputs for seven years (1998–2004). Energy use efficiency indicators employed include: energy intensity (EI), energy cost per unit product (EC/P), energy ratio (ER), food energy ratio (FER) and percentage oil yield by weight. Results of the study indicated that averagely, 0.58, 0.53 and 0.74 GJ/10³ l of PKO were needed in the small, medium and large PKO factories, respectively. The average food energy ratios in the small, medium and large mills are 2.48, 2.53 and 2.14, respectively. The corresponding values of PKO conversion ratio are 0.43, 0.50 and 0.35. Electrical energy consumption in medium and large mills was lower than thermal energy due to irregularity and decline in electricity supply from the national grid. The results of the study has provided required baseline information needed for budgeting, comparison of yearly energy consumption, forecasting energy requirements and planning expansion in PKO factories.     

Transesterification of jojoba oil,sunflower oil,neem oil,rocket seed oil and linseed oil by tin catalysts

The methanolysis of jojoba oil has been studied in the presence of tin powder, dibutyltin diacetate (C₄H₉)₂Sn(OOCCH₃)₂, dioctyltin diacetate (C₈H₁₇)₂Sn(OOCCH₃)₂, dibutyltin oxide (C₄H₉)₂SnO, dioctyltin oxide (C₈H₁₇)₂SnO, diphenyltin oxide (C₆H₅)₂SnO, dibutyltin chloride dihydroxide (C₄H₉)₂Sn(OH)₂Cl, butyltinhydroxide hydrate (C₄H₉)Sn(=O)OH.xH₂O, Ni nanoparticles and Pd nanoparticles act as catalysts. Among these, 1 weight % of dibutyltin diacetate shows the maximum conversion. Then, methanolysis of sunflower oil, neem oil, rocket seed oil and linseed oil into methyl esters studied in the presence of 1% dibutyltin diacetate as a catalyst and was compared their percentage conversions. The experimental yield for the conversion of jojoba oil, sunflower oil, neem oil, rocket seed oil and linseed oil into biodiesel was found to be 71%, 51%, 50.78%, 40.90% and 39.66%, respectively. The experimental yield of the conversion of jojoba oil into methyl esters was found to be increased up to 96% by increasing reaction time, without emulsion formation. The synthesis of jojoba seed oil biodiesel (JSOB), soybean oil biodiesel (SOB), neem oil biodiesel (NOB), rocket seed oil biodiesel (RSOB) and linseed oil biodiesel (LSOB) was confirmed by NMR (¹H & ¹³C) and FT-IR analyses of biodiesel.     

着火油罐稳定燃烧时的辐射热分布

在Mudan模型的基础上,建立了着火油罐稳定燃烧时的热辐射模型,并计算了油罐周围辐射热流的水平和垂直分布,得出了其相应条件下的变化趋势。为验证其准确性,与汽油和柴油罐的火灾实验结果对比,吻合程度良好。对于油罐消防安全的工程设计以及火灾中灭火战术的制定都具有指导意义。     

Preparation, characterization and application of heterogeneous solid base catalyst for biodiesel production from soybean oil

A solid base catalyst was prepared by neodymium oxide loaded with potassium hydroxide and investigated for transesterification of soybean oil with methanol to biodiesel. After loading KOH of 30 wt.% on neodymium oxide followed by calcination at 600 °C, the catalyst gave the highest basicity and the best catalytic activity for this reaction. The obtained catalyst was characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), N₂ adsorption-desorption measurements and the Hammett indicator method. The catalyst has longer lifetime and maintained sustained activity after being used for five times, and were noncorrosive and environmentally benign. The separate effects of the molar ratio of methanol to oil, reaction temperature, mass ratio of catalyst to oil and reaction time were investigated. The experimental results showed that a 14:1 M ratio of methanol to oil, addition of 6.0% catalyst, 60 °C reaction temperature and 1.5 h reaction time gave the best results and the biodiesel yield of 92.41% was achieved. The properties of obtained biodiesel are close to commercial diesel fuel and is rated as a realistic fuel as an alternative to diesel.