Carbon in coal

Chemical reactions, such as the burning of carbon in coal with oxygen, also get energy from rearranging electrostatic forces, but those forces arc much smaller and consequently chemical energies released per atom are much smaller than nuclear energies released per nucleus. 

The process will adversely affect air quality by releasing nitrogen oxides, sulfur oxides, carbon monoxides and other particulates into the atmosphere. Better control of the conversion conditions and better control of emissions can make the process cleaner, yet technology cannot do anything to curb carbon emissions. Since much of the carbon in coal is converted to carbon dioxide in the synthesis process, and is not part of the synthetic fuel itself, the amount of carbon dioxide that will be released to the environment during combustion is 50 to 100 percent more than coal, and around three times more than natural gas. 

As stated before, volatile carbon % is considered to be one of the most important parameters of hydroliquefaction. Also a fairly good linear relationship between the volatile carbon % in coal and low temperature tar yield from coal is found in Morwell brown coals, based on the data from the State Electricity Commission of Victoria (SECV) in Australia, as shown in Fig.9 Therefore, the low temperature tar yield is also estimated to be an important parameter. In addition, the color tone of brown coal (lithotypes) is shown in this figure. From this figure, it is observed that both volatile carbon % and low temperature tar yield are in a fairly good relation to the color tone of brown coal. Thus, as proposed by the Australian researchers, the color tone of brown coal is considered to be an important parameter. 

The carbon in coal can exist in two forms, volatile carbon and base carbon. Volatile carbon is released by pyrolysis while base carbon remains as a residual char or coke. Both forms of carbon in coal have been utilized in the development of synthetic fuel. 

It had been observed earlier (J7, J8, 19) that in coals of 80-90% carbon content (on dmf basis) the sum of aromatic and hydroaromatic fractions appears always to be almost constant at 92 2% of the total carbon in coal. The balance of 6-10% could thus be aliphatic carbon. The accuracy of such an estimate obviously would depend upon the accuracy of the aromaticity and hydroaromaticity values. The conclusion that the sum of aromatic and hydroaromatic carbon fractions is nearly constant at the region of 92-93% of the total carbon has also emerged from the recent deductions made by A. F. Gaines (11) and the authors (20) by interpreting infrared and NMR data. 

MAZUMDAR FT Al. Aliphatic Structures in Coal (Assussud From Pyrolysis) with Othor Forms of Carbon in Coal... 

The technique for estimating the total aliphatic carbon (especially methyl carbon) in coal may require further refinements. However, in view of the foregoing discussions on the self-consistency of the estimated methyl content with other forms of carbon in coal, it seems unlikely that there are side chains longer than methyl group in normal coals. 

Several of the minor components of coal are of importance, because of the quantity present on occasion, but more so in some cases by virtue of the special properties they possess which are undesirable when the coal is used for certain purposes. For example, to arrive at a correct figure for the combustible carbon in coal, it is necessary to apply a correction for the quantity of carbonate associated with the sample. Combustion analyses determine only the total carbon. Again, coking coals should have low phosphorus content, and anthracites used for malting should contain only very small quantities of arsenic, so that the determination of these elements becomes necessary in certain cases. Since both are found normally in small amounts, they are not included in the general statement of the ultimate analysis but are reported separately. 

ASTM D-1756. Standard Test Method for Determination as Carbon Dioxide of Carbonate Carbon in Coal. 

From the standpoint of the chemical changes involved, the production of iron from an oxide ore (or from a carbonate or sulfide ore after roasting) may be represented in terms of a few simple reactions. The raw materials required are the ore, limestone, and coal or coke. The carbon in coal or coke is first changed to carbon dioxide, which in turn is passed over layers of hot coke to convert the dioxide to carbon monoxide. 

Metal oxide was mixed with coal (0.2g) at a molar ratio of oxygen in metal oxide to carbon in coal = 1.2. 

Fig. 18. Effect of coal particle size on the percentage conversion of carbon in coal to acetylene in an argon plasma. (Redrawn from Bond, R. L., Ladner, W. R., McConnell, G. I. T. in Advances in Chemistry Series No. 55, page 659 (1966), Gould, R. (ed.), by permission of Dr. Ladner and the publishers, the American Chemical Society)...

Hydrogen generates additional acetylene from the carbon in coal via solid carbon-gaseous hydrogen reaction, a yield contribution which is absent in an inert atmosphere. 

Figure 3. Conversion of carbon in coal to hydrocarbon gases, carbon monoxide, and carbon dioxide vs. reactor temperature...

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