Fuel
The photoacoustic effect is investigated as a method for measuring unburned carbon in fly ash. The technique has the potential for automatic, on-line measurements without interference from fly ash constituents other than unburned carbon. Two excitation sources were investigated in this study: 0.632 μm optical radiation from an He-Ne laser and 2450 MHz microwave radiation with a free space wavelength...
Differences between the compositions of partly hydrocracked hexane-soluble extract fractions from the liquefaction of maceral concentrates were investigated by gas chromatography-mass spectrometry. the technique identifies components within only a relatively narrow range of molecular masses, but some systematic differences were nevertheless observed. Dibenzofuran derivatives were significantly more...
Three coals of different rank (R 0 = 0.58-1.01%), and the lithotypes and macerals separated from these coals, were analysed in this study. The wet chemical technique was used to determine the distribution of sulfate, pyritic and organic sulfur forms in the coals and lithotypes. The morphology, size and mode of occurrence of pyrite were examined by optical microscopy and scanning electron...
The exhaust from a direct-injection light-duty diesel engine was sampled for polycyclic aromatic compounds (PAC) at three constant speeds and at five load settings for each speed, using a total-exhaust solvent-stripping apparatus. Exhaust samples were analysed for 3- and 4-ring polycyclic aromatic hydrocarbons (PAH) and dibenzothiophene by g.c.-m.s. in electron-impact mode. The PAC recoveries (per...
Gas chromatography (g.c.) and gas chromatography-mass spectrometry (g.c.-m.s.) analyses of fatty acids directly extracted by organic solvents from five sulfur-rich lacustrine sediments in the Nordlinger Ries comprise several homologous series. Saturated normal monocarboxylic acids (C 9 -C 3 3 ) were the dominant series, while isoprenoid acids (C 1 4 -C 2 1...
Montana Rosebud coal and North Dakota lignite have been oxidized in a fluidized bed reactor at 200°C, with air at 0.2, 0.6 and 1 MPa for reaction times up to 4 h. Oxidized samples were analysed by reflected light microscopy to investigate the variation of reflectance, formation of rims and changes in maceral morphology. The most remarkable changes concerned the vitrinite. Exinite exhibited an increase...
The terpene content of an Italian lignite was investigated by catalytic hydrogenation of its steam distillate and some reference terpenes. G.c. and g.c.-m.s. analyses of hydrogenated crudes confirmed previous identifications and revealed intermediate structures formed by partial reduction and the presence of bicyclic diterpenes with MW 278. Of the reference terpenes used for comparison with 210...
The increasing demand for diesel fuel has resulted in an increase in the number of blend streams including cracked components from secondary processes using mostly heavy crudes of different origins. Owing to such compositional changes, the existing property blending equations may no longer be sufficiently accurate. Therefore, the development of new correlations was required. In this work, three...
Direct observation of pulsed-laser ignition and combustion of pulverized coals with a high speed video has been made. A dilute stream of particles was dropped into a laminar, upward-flow wind tunnel with a quartz test section. The gas stream was not preheated. A single pulse from a Nd:YAG laser was focused through the tunnel and ignited several particles. The transparent test section and cool...
A commercial coal liquefaction catalyst, Amocat 1A, has been subjected to a deactivation study in a laboratory catalytic coal liquefaction microreactor. Carbonaceous and metal deposits were the two major factors causing catalyst deactivation. The carbonaceous material deposited primarily in the interior of the catalyst particle and clogged the pores in a uniform manner. The metals deposit was rich...
A laser heating technique was developed to study the fragmentation behaviour of calcium-based sorbents under high heating rate, short residence time conditions. Eight geologically dissimilar, commercially available calcium-based sorbents were tested in the reactor using particle sizes in the range 37-105 μm. The fragmentation behaviour was a function of sorbent type, particle size and particle temperature...
CO 2 gasification of a gas-coal char catalysed by Na 2 CO 3 and K 2 CO 3 was studied using a fixed-bed reactor at 790-1020°C and 0.2 MPa. The gasification rate increased with increasing temperature. With increasing addition of Na 2 CO 3 in the range 9-25 wt% and K 2 CO 3 in the range 5-20wt% the rate increased sharply. The...
A coking coal containing 4.9 wt%, db, of sulfur was subjected to pyrolysis at 330-1700°C in an atmosphere of evolved gases. The changes in the forms of sulfur were determined by wet chemical analysis. Scanning electron microscopy (SEM) combined with X-ray microanalysis were used to monitor the reduction of pyrite during coal pyrolysis and the retention of sulfur by the alkali constituents of the...
Six methods were tested for the prediction of the surface tension of naphtha reformate and crude oil fractions. The corresponding-state method gave the lowest deviation from experimental values for single cuts. The surface tension-density correlation method gave the lowest deviation for a blend of several cuts.
The elemental compositions of framboidal pyrite and associated maceral types of a Devonian oil shale were investigated using a micro-analysis particle-induced X-ray emission (PIXE) technique. The majority of the PIXE analyses were performed using a 750 keV proton beam to investigate sulfur and iron concentrations. Trace metals in the framboids and associated macerals were analysed using a proton...
K-edge XAFS spectroscopy has been used to examine directly the occurrence of chlorine in a variety of coals worldwide. Chlorine XAFS spectra were also obtained for Illinois No. 6 coal before and after aqueous leaching and conventional coal cleaning and during low-temperature (<350°C) slow pyrolysis under helium, and for coals treated with chlorinated reagents. The chlorine XANES spectra for coals...
Reflectance measurements have been used to try to track the structural alterations during activated carbon synthesis by chemical activation. H 3 PO 4 has been used as a chemical reagent with white oak, subbituminous coal and a bituminous coal, and KOH with a bituminous coal. The reflectance of thermally treated carbons follows a single correlation with heat treatment temperature (HTT),...
This paper presents a model for group combustion of a cylindrical stream of coal particles and preliminary experimental data. Results are obtained for transient ignition and combustion behaviour. It is found that homogeneous ignition (ignition of volatiles) occurs for a dense cloud, while heterogeneous ignition (ignition of carbon) occurs for a dilute cloud. Once ignited, the flame moves towards...
X-ray photoelectron spectroscopy (XPS) was used to investigate the nitrogen functional forms present in several coals and their chars. The chars were prepared under different severity conditions to capture transformations in nitrogen functionality occurring during pyrolysis. It has been demonstrated that nitrogen present in coal in pyrrolic forms is converted into pyridinic functionalities upon...
Mercury porosimetry was used to study changes in the pore structure of three western Canadian low-rank coals treated in three different atmospheres (nitrogen, steam and combustion products) at temperatures up to 500°C. The intrusion curves are well described by two different power laws in the pressure range 0.1-200 MPa. Principal-component analysis was performed to determine relations among the...