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In order to develop a reaction simulator for purposes of direct coal liquefaction, a kinetic model for the initial stage of the reaction was developed for sub-bituminous Wandoan and Tanitoharum coals. The kinetic parameters in the model were determined by fitting the model to experimental data obtained by autoclave tests. Based on the model, a simulator for a preheater was proposed. The yields of...
Eight parent samples, obtained from a commercial anthracene oil by air-blowing under different conditions, were thermally treated in nitrogen between 350 and 390°C for 3–8h. Changes in the composition, pyrolysis behaviour and microstructure of the resultant cokes were studied by standard procedures (i.e. elemental analysis, softening point, etc.), Fourier transformed infrared spectroscopy, size exclusion...
In this paper, the effect of water content on combustion characteristics of watery waste material, such as kitchen garbage, was studied experimentally. In order to clarify the water content quantitatively, a permeable balsa wood was chosen as the sample material. Combustion tests of the small balsa pieces (0.1–0.5g) containing water up to 70wt% were conducted in a thermogravimetric furnace. Mass reduction...
In modelling the fate of minerals of pulverised coal in coal-fired boilers, ash formation is a primary step that decides ash particle size distribution and composition. Frequently, two extreme schemes have been used regarding mineral coalescence behaviour within individual char particles, i.e. no coalescence and full coalescence. However, their implications on ash deposition and thermal performance...
This study evaluates the effect of blending on the combustion characteristics of pulverised coal through the testing of six coals and fifteen coal blends in an isothermal plug flow reactor (IPFR). The aim of the test was to assess whether the combustion behaviour of blends could be predicted from that of the parent coals. For blends of bituminous coals, an additive behaviour was found for ash, volatile...
Temporal changes in solvent content of deposits formed on a tube wall were measured for a binary system of hydrocarbons, nonadecylcylohexane and octane. Solvent content in the deposited nonadecylcyclohexane decreased over time, consistent with the phenomena of migration of included solvent in a temperature gradient. An understanding of inclusion migration in deposits can provide a framework for modeling...
The coking pressure in a coke oven, which is caused by the internal gas pressure in the coal plastic layer, is determined by the gas permeability of the layer. The gas permeability of the plastic layer depends on its density as well as the physical property of the plastic coal itself. The plastic layer is sandwiched between the coke and the resolidifying layers and the coal layer and the effect of...
A heat transfer method was used to calculate wax thickness formed from a flowing binary system of hydrocarbons, nonadecylcylohexane and octane. Wax thickness increased steadily with time reaching an asymptotic value. The results obtained with the heat transfer method were in good agreement with the results obtained from gravimetric data. The heat transfer method seems to be a reliable method of calculating...
Mechanisms proposed by Roscoe and Thompson as well as by Dean were used to investigate the influence of back-mixing on the decomposition of methane. Increasing degrees of back-mixing were simulated by decreasing numbers of vessels in series. It is shown that back-mixing has a significant effect on the decomposition of methane; the rate may be increased by more than one order of magnitude. The results...
The large variety in municipal solid waste (MSW) composition and differences in thermal degradation behaviour of MSW components makes modelling, design and operation of thermal conversion systems a challenge. The pyrolysis characteristics of 11 different components, representing the dry cellulosic fraction and plastics of MSW, have been investigated. The aim of this study is to obtain detailed information...
Batch experiments were conducted to investigate the emissions of carbon oxides and nitrogen oxides from the combustion of char prepared from a commercial coal in a bubbling fluidized bed. Combustion gases escaping from the surface of the bed were sampled and analyzed for N 2 O, NO, NO 2 , CO and CO 2 as a function of time by means of a Fourier Transform Infrared Spectrometer...
Three limestones and three spent calcium sorbents with differing sulfation patterns were subjected to sulfation and steam hydration at 250 and 450°C in an effort to identify the optimum conditions for increasing their ability to capture sulfur. Visual and chemical investigations of the hydrated and resulfated samples using a scanning electron microscope indicate that the sulfation pattern controls...
This paper presents the experimental results on the slagging propensity of three pairs of blended coals tested in the Australian Coal Industry Research Laboratory furnace. The results showed that none of the coals or blends produced strongly molten deposit. At worst, the deposits contained some moderately sintered material. Most of the blends have (slightly) worse slagging behavior than the component...
Thermal decomposition under nitrogen of sugarcane bagasse, petroleum residue and their blends was studied by thermogravimetry (TG) at different heating rates (10, 20, 40 and 60°C/min). Thermal decomposition kinetic parameters were determined. Sugarcane bagasse pyrolysis was described as the sum of cellulose, hemicellulose, and lignin individual contributions. First order equations were used to determine...
Limestone addition to a coal-fired fluidized bed combustor usually results in an increase in NO/NO x emissions and a decrease in N 2 O emissions. This observation has been explained in the literature by the effect of limestone on: (i) the conversion of coal volatile-N to NO/NO x and N 2 O; (ii) the decomposition of N 2 O; and (iii) the pool of H, OH and/or O...
1 H-NMR spectroscopy is a potentially useful technique for the characterisation of coal. A novel technique was applied to distinguish, characterise and determine quantitatively five different classes of proton containing components from air-dried Australian bituminous coals. The five different classes of protons are described by 14 fitted NMR parameters, which are the signal amplitudes, spin–lattice...
Evidences of asphaltene aggregation are presented through the application of the Z-scan technique to study the nonlinear optical response of solutions of asphaltenes in toluene. Strong dependence of the two photon absorption coefficients (β) with the input intensity was observed for concentrated solutions, as opposed to the observed behavior at low concentration. The results suggest that a change...
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