Coal during

Release behavior of trace metals from coal during high temperature processing... 

The second procedure studied the effects of the sulfur content of the coals during hydrogenation. A suite of unwashed... 

It is possible to produce some liquid hydrocarbons from most coals during conversion (pyrolysis and hydrogenation/ catalytic and via solvent refining)/ but the yield and hydrogen consumption required to achieve this yield can vary widely from coal to coal. The weight of data in the literature indicate that the liquid hydrocarbons are derived from the so-called reactive maceralS/ i.e. the vitrinites and exinites present (7 8 1 9). Thusf for coals of the same rank the yield of liquids during conversion would be expected to vary with the vitrinite plus exinite contents. This leads to the general question of effect of rank on the response of a vitrinite and on the yield of liquid products and/ in the context of Australian bituminous coals, where semi-fusinite is usually abundant/ of the role of this maceral in conversion. 

A project initiated by the author when with CSIRO has, as one of the objectives, the study of effect of the mineral matter in selected Australian coals during catalytic hydrogenation (13). 

A system based upon the reactivity of coals during extraction with anthracene oil and phenanthrene has been developed. A convenient graphical method of expressing the data on Seyler s chart has been adopted. This method has limitations when dealing with prime coking coals, which show wide variations in extraction yield. The differences in extraction yield relate to the concentration of inertinite which is virtually insoluble in anthracene oil. 

To describe in fundamental terms the dissolution of coal in a hydrogen-donor solvent requires an experimental approach that allows the chemical changes that occur within the coal during dissolution to be discussed. This, in turn, requires a direct method of determining the structural features in coal before it is reacted. 

The preceding experiments offer preliminary support to our notion that pericyclic pathways might be intimately involved in the mechanism of coal liquefaction. More specifically, the results indicate that pericyclic group transfer reactions constitute a plausible pathway for the transfer of hydrogen from donor solvents to coal during liquefaction. 

Smith, R. D. 1980. The trace element chemistry of coal during combustion and the emissions from coal-fired plants. Progress in Energy and Combustion Science, 6, 53-119. 

Evaluating the quantitative effect of these factors on the volatile mercury concentration requires determining how much of the initial mercury found in the coal is 1. not volatilized from the coal during combustion, 2. recovered in the various ash collection mechanisms by some adsorption phenomena, and 3. released to the atmosphere. With this information, a mercury mass balance can be calculated in which the amount of mercury consumed during the combustion process is compared with the amount in the stack gas and the various ashes. During this study, this was accomplished by comparing the stack gas concentration with the amount of mercury initially in the coal, corrected for the amounts recovered in the ashes. Differences between these two values would represent adsorption and/or desorption onto and off the walls of the ducts and stack and any significant contribution from the ambient air used in the combustion process. 

The samples were quartered as quickly as possible in air and then crushed and sieved in a dry box containing a nitrogen atmosphere. This procedure was followed to minimize oxidation of the coal during the sizing operations. Fractions of 6-8 mesh and 89-100 mesh were used. 

It was found that removing only 12% of coal during the first stage of extraction increased the initial apparent entropy of activation from a negative to a positive value. It further shows that this value increases as x increases. This is expected if the surface area available for reaction increases during the course of the reaction. 

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