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Based on the principle of intermolecular forces for non-polar compounds, a simple relation is proposed for the estimation of viscosity of liquid hydrocarbons and petroleum mixtures at various temperatures from the knowledge of refractive index. Also some experimental data on the viscosity of some Kuwaiti light and medium petroleum fractions are reported. Evaluation of the proposed method shows that...
Two activated carbons of different texture were modified by carbon deposition from the pyrolysis of benzene, in an attempt to obtain carbon molecular sieves of high adsorption capacity and selectivity for the separation of O 2 /N 2 mixtures by pressure swing adsorption (PSA). The results show that these objectives can be attained when the carbon precursor has been activated only to...
The need to rationalize the use of the conventional existing fuels, associated to the impositions of severe legislation for controlling the level of emissions, has been demanding the development of optional fuels and the increase in the efficiency of the current engines. This study presents new microemulsion systems containing diesel and different percentages of vegetable oils (soy, palm and ricin),...
The reductive alkylation of a French petroleum asphaltene (Lagrave) was studied with potassium in THF, in absence of an electron transfer reagent. From the number of butyl and benzyl groups added to the starting asphaltene, the difference of reactivity of the alkyl reagents, butyl iodide and benzyl bromide, was pointed out. Special attention was focused on the cleavage of C-S and C-O linkages in relation...
The behaviour of HZSM-5 zeolite in the upgrading of a wood pyrolysis oil produced in the ENEL fast-pyrolysis plant located in Bastardo, Italy, was studied in repeated upgrading-regenerating cycles. The HZSM-5 zeolite performs a catalytic activity by its acidic sites that, through a carbonium ion mechanism, promote deoxygenation, decarboxylation and decarbonylation of the oil constituents, as well...
The contact of acid with crude oil generates a reaction product known as acid-sludge which has been interpreted as polymerised asphaltenes due to Friedel-Crafts reactions. A size-exclusion chromatographic analysis of crude oils and fractions showed, however, that acid-sludge is composed of small molecules. The greatest increase in molecular weight was observed for the nonpolar fractions. The results...
The spontaneous combustion of coal stockpiles is a serious economic and safety problem. This phenomenon is herein analysed using a TNO-model modified to predict the spontaneous heating behaviour of coal piles built with ''Mezcla'', a mixture of low rank coals from Teruel (Spain). The simulation carried out with the mathematical model for this coal showed that the pile porosity or voidage and wind...
Four commercially available coal tar pitches have been characterised through the combination of conventional techniques used for pitch characterisation, like elemental analysis and solvent fractionation, and infrared spectroscopy (FTIR) and thermal analysis (thermogravimetry (TG)-differential thermal analysis (DTA)). The results obtained from this set of experiments provide suitable information to...
The paper discusses the development of a numerical simulation model ''COALTEMP'' to study the oxidation and possible spontaneous combustion of coal, that is exposed to the atmosphere and the daily cycle of solar irradiation. First the differential equations that describe heat flow, oxygen flow and oxidation in the coal matrix, and the equations describing the exchange of heat, radiation and oxygen...
The combustion of lean, stoichiometric and rich hydrogen-air mixtures in well-stirred reactors has been modeled in the temperature range 1500-2200K employing a detailed H/N/O reaction scheme, and a H/O reaction scheme together with algebraic expressions for the NO production rate as a function of local gas composition and temperature. Thermal-NO, nitrous oxide, and NNH mechanisms of nitric oxide formation...
A review has been made of the various methods of determining major and trace element affinities for different phases, both mineral and organic in coals, citing their various strengths and weaknesses. These include mathematical deconvolution of chemical analyses, direct microanalysis, sequential extraction procedures and density fractionation.A new methodology combining density fractionation with mathematical...
Several techniques are available in the literature to estimate the K-values. In this paper, results of PVT analysis for 22 crude oil samples from different reservoirs in UAE are used. Sixty-eight single-stage flash laboratory experiments were conducted for these samples. Material balance techniques were used to extract the K-values of crude oil components. These K-values were then correlated and compared...
The most significant constituents which control the properties of coking coals are vitrinite and fusinite. For better understanding of the devolatilisation characteristics of coking coals, vitrinite-rich and fusinite-rich concentrates were produced from Russian coking coals of rank (R o ) varying from 0.80 to 1.54. The generation of the maceral concentrates was carried out by repeated cycles...
Emission of CO, NO x , N 2 O and SO 2 from a 71MW PFBC was continuously observed for 8days while the plant load, the level of coal load, the concentration of emission gases, total pressure, and temperature varied dynamically. Prediction of concentrations of such gases are attempted in this paper to prove the high accuracy of a series of ASH TR equations proposed...
Systematic measurements are reported of OH chemiluminescence from a premixed laminar flame at pressures and equivalence ratios ranging from 0.5 to 2.5MPa and 0.66 to 0.86, respectively. The objective was to obtain non-existent experimental data and to determine the viability of using OH chemiluminescence as an active-control parameter for high-pressure, premixed flames. The signal from the first electronically...
In order to study nitrogen release from different nitrogen structures during coal pyrolysis, two model coals containing pyrrolic or pyridinic nitrogen have been prepared using cellulose and phenolic nitrogen compounds. Nitrogen release during pyrolysis of the model coals without and with catalyst has been studied in a fixed-bed reactor at 50 o C/min up to 1000 o C. The pyrolysis results...
Danish power stations use coals, imported from various countries around the world. Since the coals may differ considerably in burning properties, the purchasers have a marked interest in characterization of the coals prior to use. In a Danish project existing methods were compared, using ten selected coal samples and equipment and techniques for particulate coal in the USA and Sweden were also used...
A laser technique of transient burning rate measurement of solid propellant has been investigated. A photocell detects a laser beam passing through the propellant strand, and the cross-section of the laser beam is regulated so that the laser energy varies linearly along the height of the strand. Using a photo-controlled depressurization system, it is desirable to set up the starting time of depressurization...
Drying of coal in steam offers, besides reduction of fire and explosion hazards, improved thermal efficiency. In addition, steam-dried coals appear to be less prone to spontaneous combustion. In a previous paper, a mathematical model was developed for the drying of a single porous particle in steam. In this paper, the single particle model has been integrated with a two-phase hydrodynamic model to...
This paper presents a numerical simulation of particle motion and combustion in a pulverized coal-fired sudden-expansion combustor with coaxial jets. The computations are conducted for both bituminous and lean coal flames. The obtained results show the trajectories and the mass and temperature variations with time for coal particles of different initial sizes. It is seen that the interactions between...
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