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Coal injection is an important technique for increasing the efficiency of blast furnaces, although the required optimum properties of injectant coals have not yet been fully identified. The Single-Tuyere Coal Injection Investigation Rig at the British Steel Teesside Technology Centre is a pilot-scale blast furnace simulation operated without iron ore so that the combustion (and gasification) of the...
The release of nitrogen oxides during coal combustion has a major environmental impact. In low-NO x burners and fluidized bed combustors the char nitrogen is the major contributor to nitrogen oxide emissions. In this review the release of nitrogen oxides during the combustion of chars is considered in relation to coal and char structural characteristics. The changes in the nitrogen functionality...
In the BGL slagging gasifier, graded coal is gasified in a fixed reactor. A study has been made of the carbonization of large particles (∼25-30 mm) of three high-volatile UK bituminous coals at pressures in the range 0.5-8 MPa in an autoclave using a shock beating technique. The cokes were characterized in detail and compared with the corresponding high-pressure cokes produced under slow heating...
This paper describes a study of the effect of pyrolysis temperature on the macromolecular structure of coal, using solvent swelling techniques. Heat treatment initially dissociates the intermolecular interactions in the coal and cleaves some cross-links, leading to increase in the solvent swelling of the coal, which indicates a decrease in the cross-link density. The solvent swelling reaches a maximum...
In cokemaking, the generation of swelling pressure is an important consideration since excessive pressures result in problems with pushing the coke and in extreme cases, damage to coke ovens may occur. In this investigation, the effect of swelling pressure generated during coal carbonization in coke ovens on coke porosity was studied. The swelling pressure was measured using a movable-wall test...
The temperature-programmed combustion of coal was studied and reactive intermediates were observed by gas sampling directly above the sample in a thermogravimetric analyser-mass spectrometer (t.g.a.-m.s.). Species detected included OCS, OCN, HCN and (CN) 2 . NO levels observed at the exit of the t.g.a. differed from those measured directly above the sample, the former usually being higher...
The effect of pyrolysis conditions on the release of nitrogen during char combustion was investigated. A fluidized bed pyrolysis unit was used to produce several chars at different temperatures and pressures from a Spanish coal. In this way, a number of chars differing in volatile matter and specific surface area were obtained. Gas evolution profiles of CO, CO 2 , NO and N 2 from...
The relations between the gas pressure developed during carbonization in coke ovens, the changes in the coal macromolecular structure, thermoplastic properties, devolatilization with respect to temperature and coke porosity were investigated. The macromolecular structure, i.e. the apparent cross-link density, was characterized by the solvent swelling technique using pyridine as solvent for coals...
The development of coal thermoplasticity during the primary devolatilization region is critical in determining coke structures. The solvent swelling technique was used to study the changes in macromolecular structure of four coals of different rank (902 to 203 in the British Coal classification scheme) during carbonization to temperatures up to 600°C. The results were compared with the thermoplastic...
The development of coal thermoplasticity during the primary devolatilization region is critical in determining coke structures. The solvent swelling technique was used to study the changes in macromolecular structure of four coals of different rank (902 to 203 in the British Coal classification scheme) during carbonization to temperatures up to 600 o C. The results were compared with the thermoplastic...
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 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...
The combustion behavior of a suite of isotropic carbons has been investigated using a thermo-gravimetric analyser mass spectrometer. The carbons were prepared from polyvinylidene chloride (PVDC) and a phenolic resin by carbonisation under argon to 873 K in the pressure range 0.1-7.5 MPa. Nitrogen was introduced into the carbons (HTT 873 K) by both ammonia treatment at the final heat-treatment temperature...
The influence of structural characteristics, in particular heteroatom content, on the ammoniatreatment of carbon-13 materials has been studied. The resulting carbon-13 materials were investigated for their temperature-programmed combustion characteristics by thermogravimetric analysis-mass spectrometry (TG-MS). The use of ca 99% isotopically pure carbon-13 allowed the analysis of N 2 O and...
The release of nitrogen and sulfur during the combustion of coal chars is a major environmental problem. Model coal chars, prepared by the high-pressure carbonisation of polynuclear aromatic precursors to 873 K and subsequent calcination at atmospheric pressure to 1273 K, were studied using temperature-programmed combustion (TPC) in 20% O 2 . These carbons, which are derived from pure organic...
Commercially available carbon molecular sieve (CMS) materials, from a variety of sources, and molecular sieving carbons produced from the carbonization of coal have been studied. These materials have been assessed in terms of their kinetics of adsorption of oxygen and nitrogen. The diffusion kinetics of gases into the carbons have been analysed using Fickian and phenomenological models. The Arrhenius...
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