Fuel
The inelastic neutron-scattering (INS) spectra from 30 to 4000 cm - 1 of four coal samples of different rank (subbituminous A, low-volatile bituminous, semianthracite and anthracite) at 20 K are reported. For each coal, rather broad bands superimposed on a continuum with almost constant intensity over the whole frequency range are observed. This continuum is assigned to recoiling free...
To meet the legislation on limiting NO x and SO x emission from large combustion plants, SO 2 emissions may need to be reduced by about 60-70%. The authors' technique for achieving significant reduction in SO 2 emissions from combustion systems burning large coals utilizes limestone for in situ reduction of SO 2 in fluidized bed combustors. A recent technique...
Evolution of volatiles and structural changes in green petroleum coke during its pyrolysis under nitrogen was studied by thermogravimetry in an induction furnace. Four cokes were examined in a particle size of 417-833 μm between 450 and 1200°C at heating rates of 40, 90 and 150 K min - 1 . The weight loss and hydrogen and methane concentrations were measured, as well as the apparent...
A novel loose-pack dilatation (LPD) method for coal dilatatometry is described and validated. It uses slightly modified Ruhr or Audibert-Arnu apparatus. The test sample consists of a weighed amount of coal which is directly transferred into the retort tube. Requirements of ISO methods associated with using pulverized coal to prepare pencil are eliminated, so the LPD method is easier and more versatile,...
The effects of solvent molecular size on the equilibrium swelling ratio and kinetics of the swelling of a high-volatile bituminous coal in straight-chain amines were examined. The swelling ratio increases with amine size up to a critical level, above which the swelling ratio decreases. This decrease is attributed to reduced access of the solvent to the coal structure with increasing molecular size...
The tar-decomposing activities of dolomites and limestones in calcined and carbonated forms were compared. Tests were carried out in a fixed-bed tube reactor at 900°C under 2 MPa total pressure using an N 2 -H 2 O-CO 2 gas mixture. Toluene was used as a tar model compound. The calcined rocks decomposed toluene efficiently, but activity was almost totally lost in the carbonated...
A characterization of pyrolysis behaviour of different refuse derived fuels (RDFs) under heating rates typical of conventional pyrolysis processes is presented. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (d.s.c.) on different RDFs, and on some materials which have been considered key components towards thermal degradation characteristics of RDFs, are...
Mixtures of 2 and 4 wt% of pure paraffins in a crude oil matrix and 14 crude oils were characterized by differential scanning calorimetry (d.s.c.) and thermomicroscopy at a cooling rate of 2 K min - 1 in the temperature range from +80 to -20°C. Pour points were also determined. In the temperature range used, a constant value of 200 J kg - 1 for the enthalpy of precipitation...
High-silica zeolites (US-Y and ZSM-5) were used to adsorb organics from retort waters derived from Stuart oil shale (Queensland, Australia). Removal of organics increased with decreasing polarity of the adsorbate and improved when free ammonia was removed first by air stripping. Zeolites were more effective than activated carbon. They are easily regenerated and are potential agents for pretreatment...
The phase transition temperatures and energies of petroleum waxes derived from Bombay High middle distillate were determined. The effects of iso- and cycloparaffins and aromatics, individually and collectively, on these parameters were investigated. The influence of a commercial pour-point depressant additive and its concentration on the same parameters were also studied. The mechanism of pour-point...
Trifluoromethanesulfonic acid (TFMS) was found to convert coal almost completely to pyridine-solubles in the presence of isopentane at 150°C in 3 h under autogenous pressure of 6.0-6.8 MPa. The chemical structure of the benzene-soluble and THF-insoluble-pyridine-soluble fractions varied with the acid concentration. Lower acid concentrations provided high aromaticity and rich H a r and...
A simple procedure has been developed to isolate the basic and neutral nitrogen compounds from a Brazilian diesel distillate through acid partition and open column chromatography using alumina. With minimum sample preparation and clean-up, isolated fractions were analysed by particle beam liquid chromatography-mass spectrometry (l.c.-m.s.) using both reversed phase and normal phase chromatography...
Extractability of Assam coal by quinoline was enhanced to 90% by prior reaction with cetene or cetanol in anthracene oil. The reaction is a complex series reaction: alkylation-transalkylation-dehydrogenation-degradation-disintegration (called the ATD 3 reaction). The reaction conditions for this reaction (reaction time, temperature, reagent concentration etc.) were optimized for using...
The effect of the addition of small quantities (1 wt%) of phosphoric or polyphosphoric acid and other phosphorus compounds on the physical and chemical characteristics of straight-run (distillation) bitumens was studied. The effect was similar to that induced by a mild blowing process: the peptized material increased, with a shift towards a gel structure, and minor effects on penetration and low-temperature...
The effect of oxidation on the macromolecular structure of four coals of rank 902 to 204 in the British Coal classification scheme was investigated. Various particle size ranges of the coals were oxidized in air at 200°C for 24 h. Oxidation led to an increase in the extent of swelling in pyridine, which indicates a decrease in the covalent cross-link densities of the coals. Unlike that of the initial...
Hydrogenation of carbon dioxide and carbon monoxide on iron catalysts prepared from Fe 2 (CO) 9 and Fe 3 (CO) 1 2 supported on four activated carbons were studied. The catalysts, prepared and reduced in H 2 at 673 K for 12 h, were characterized by H 2 and CO chemisorption and TEM. The catalysts prepared from Fe 3 (CO) 1 2 had...
Coal is a complex macromolecule of predominantly aromatic character. The reaction of coal under Friedel-Crafts conditions is not a simple alkylation but involves a series of complex reactions. The molecular dynamics of coal molecules under such conditions can be studied by FT-i.r. spectrometry, elemental analysis, swelling and extraction. Several alkylating agents such as alkenes, alcohols, alkyl...
A comparative study on pyrolysis and hydrogasification of a bituminous coal was conducted under non-isothermal heating at 3 K min - 1 to 1200 K. The kinetics of C 1 -C 3 hydrocarbon formation were measured and total yields of the products were evaluated. The chemical and optical structures of the coal chars obtained at different temperatures were also investigated. At...
A series of coals ranked from lignite to bituminous were hydrogenated at 300, 350 and 400°C in the absence of a solvent and with a hydrogen pressure of 5 or 10 MPa. Conversion percentages and yields of reaction products (oils and asphaltenes) were related to coal textural characteristics. Changes in the textural parameters during hydrogenation were determined with the object of studying the reaction...
Vitrain from a bituminous coal was modified by selective chemical reaction to reveal particular structural characteristics of the organic matter responsible for the change in conversion during solubilization by methanol-NaOH treatment (M treatment). The selective reactions were alkylating and non-alkylating reduction according to Sternberg, performic acid oxidation, thermal decarboxylation of the...