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Tests were conducted on three representative vehicles of Mexico City liquefied petroleum gas fleet (LPG), using different propane/butane mixtures. Exhaust emissions, individual hydrocarbon speciation and ozone forming potential was evaluated in order to establish a LPG specification for automotive use in Mexico City. Results indicated that a change in composition from 60 to 85% propane in volume had...
The petrographic composition of 21 types of typical Chinese coals obtained directly from the power stations was analyzed. The vitrinite reflectograms of them were measured and shows an obvious difference from that of single rank coals, which suggests that the coals utilized in the power stations have the characterization of a blended coal in terms of coal rank. The index S M has been developed...
Fullerene black and cathode deposits formed by arcing graphite with naphthalene have been examined. Micro-Raman, transmission electron microscopy and differential thermal analysis show that fullerene blacks produced in the presence of naphthalene are more graphite like than those prepared in its absence. These techniques also show that the cathode deposits are altered by the presence of naphthalene...
A new bitumen model has been proposed. The model is a more complete mathematical description of the stability of bitumen in terms of three-dimensional solubility parameters. It could easily be visualised in a 3D diagram or a physical model. The model is based on the current knowledge of bitumen chemistry combined with investigations on the solubility parameters of the least soluble components of bitumen...
It has been shown that generation of methane under various mixed cultures in the presence of coal as substrate involves degradation of coal. There seems to be no single bacteria that can degrade coal from clusters of benzene rings to two to three carbon aliphatic chains that are then converted to methane by methanogenesis. Incubation period of mixed cultures from various sources such as cow dung,...
Iron-catalyzed CO 2 hydrogenation is proposed as a mechanism that occurs during natural gas formation in coalbeds. This reaction was studied in a laboratory batch reactor at temperatures simulating geologic conditions. The percentage of methane in the produced gas was typically greater than 90%, resembling natural gas composition. Fe 2 O 3 , the precursor to the active catalyst,...
Concentrations of trace elements in coal derived liquids have been investigated by inductively coupled plasma-mass spectrometry (ICP-MS) and by Mossbauer spectroscopy. Liquefaction extracts prepared from the Argonne Premium Coals and a coal tar pitch have been examined. Microwave digestion in concentrated nitric acid has been shown as a suitable method for determining trace element concentrations...
Coal science is an applied discipline, using methods of science and engineering for research into genesis, characterisation, conversion and utilisation of coal and related solid fuels. This paper describes at first the development of coal science in the last century under the driving forces of politics, economics, and technology and in interaction with the progress achieved by other scientific and...
A predictive mathematical model is proposed based on the bed hydrodynamics, reaction kinetics and the empirical correlation of pyrolysis yields to predict gasification characteristics in an internally circulating fluidized bed gasifier with a draught tube. With the justifiable assumptions, steady state mathematical equations are derived and solved numerically. The simulated results of product gas...
The aqueous chemistry of iron in souring petroleum reservoirs was modeled in the laboratory. The salt FeSO 4 .7H 2 O was allowed to react with Na 2 S.9H 2 O in synthetic seawater solutions for three days at 55-85 o C. Elemental sulfur and crude oil were added to some of the reactions. The major iron precipitates formed were carbonates and sulfides, e.g. FeCO...
This paper reports on the first stage of a study attempting to develop laboratory scale tests for the reliable determination and eventual prediction, of the effect of coal properties on the performance of coals in air blown gasifiers. The pyrolysis and gasification behaviour of a suite of coals have been matched, using a high-pressure wire-mesh reactor (WMR), with those of maceral enriched samples...
The solubility of gypsum in organic acids namely acetic, oxalic, tartaric and succinic acids at low temperature (30 o C) was studied. The results show that sulphate sulphur content increases with increasing acid concentration from 0.1 to 0.25M and decreases again at higher concentration. It is suggested that different behaviour of the acids beyond 0.25M solution could be due to incorporation...
Hallimond tube flotation experiments were carried out on two coals (bituminous and sub-bituminous) using coagulants and flocculants. The reagent concentration and pH were studied as variables. Contact angle measurements were conducted by the captive bubble technique. The results show that starch flocculant gives the largest contact angles on the coal surface for the system investigated. The contact...
A steady state model of a coal-fired circulating fluidized-bed boiler, based on hydrodynamics, heat transfer and combustion, is presented. This model predicts the flue gas temperature, the chemical gas species (O 2 , H 2 O, CO, CO 2 and SO 2 ) and char concentration distributions in both the axial and radial locations along the furnace including the bottom and upper...
A sequential digestion method is reported for the direct determination of sulphate, pyrite and organic sulphur concentrations in coals of either bituminous or sub-bituminous rank. A three stage extraction was developed, using acid digestion in a microwave oven. In the first stage, 5M HCl is used to dissolve sulphate phases in the coal. Pyrite is then extracted from the stage 1 residue using 2M HNO...
The application of fluidized bed combustion (FBC) technology to energy generation from sugar cane bagasse has been prevented, amongst other reasons, by the difficulties associated with fluidizing this material. This difficulty arises because bagasse is often lightweight and of unusual morphology, and manifests itself by either matting-up within the bed (if there is not enough inert diluent) or by...
The combustion of herbaceous biomass can lead to deposit formation on the walls of the combustion chamber and on boiler tubes. These deposits are being caused by fly ash. The aim of the present investigation was to identify the mechanisms of deposit formation, to analyse the chemical and morphological properties of the deposit, and to propose measures for deposit reduction. Special attention was given...
The fate of inorganic salts in straw-fired combustion systems was studied in Sandia's Multifuel Combustor. Special attention was drawn to the deposition of potassium, chlorine, and sulphur and the sulphation of potassium chloride to potassium sulphate. The experiments included wheat straw-firing under different combustion conditions and with elevated sulphur levels. Investigations of deposit formation...
The sulfation and steam hydration reactivation characteristics of nine limestones were evaluated based on laboratory sulfation and hydration tests and scanning electron microscope analyses. The calcium utilization and the sulfation pattern of the limestones were found to depend on the morphology and microstructure of the calcined limestones. Three sulfation patterns were observed in the limestones:...
Six immature kerogens of different geological ages, representing Types I, II and III, have been analysed by a modified Rock-Eval technique for comparison with wire-mesh pyrolysis results giving oil and total volatile yields. The hydrocarbon indices for the kerogens determined by Rock-Eval correlate approximately linearly with both oil yields and total volatiles, with consistent differences being observed...
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