Coal macerals volatile matter

H/C = atomic hydrogen-to-carbon ratio V = vitrinite content of coal VM volatile matter St = total sulfur TRM = total reactive macerals The adequacies of these reactivity correlations, expressed as a percentage of the total variation in the data set explained by the model, were 80.0%, 79.2%, and 47.5% respectively. A later paper in the series (21) concentrated on the development of reactivity correlations for a set of 26 high volatile bituminous coals with high sulfur contents, and extended the models previously developed in include analyses of the liquefaction products and coal structural features. These structural features included the usual... 

The composition of the volatile matter evolved from coal is, of course, substantially different for the different ranks of coal, and the proportion of incombustible gases increases as the coal rank decreases. Furthermore, in macerals isolated from any one particular coal, the volatile matter content decreases in a specific order thus, exinite produces more volatile matter than vitrinite, which, in turn, yields more volatile matter than inertinite. 

Studies initiated by the author in CSIRO (13) seek to throw light on the role of the various macerals by studying the conversion, under catalytic hydrogenation conditions, in Tetralin as vehicle, of maceral concentrates from a high volatile bituminous coal. Some preliminary results, given in Fig. 3, show conversions as almost complete for the hand picked vitrain (>90% vitrinite) from a high volatile bituminous coal (Liddell seam N.S.W., 83.6% carbon and 43% volatile matter both expressed on a dry ash-free basis). However, it is evident that the conversion of the whole coal increases rapidly with increase in hydrogen pressure (under otherwise similar conditions - batch autoclave, 4h. 400°C). 

It is well known that the characteristics of coal differ widely according to the age of the coal formation as well as to the location of coal, etc. And the reactivity during hydroliquefaction depends on the characteristics of coals. This relationship will he a guidance to select and develop coal mines. Many parameters to indicate the reactivity of coal have heen proposed (l, 2, 2). Among these parameters, carhon content, volatile matter content, value of H/C atomic ratio, reactive macerals content, etc. are reported to he relatively closely related parameters to coal reactivity. However, these relations are usually found only in limited reaction conditions. Therefore, attempts to find better parameters still continue. 

Separating the three macerals from the dull coal was difficult. The petro-graphical purity of the exinite is 86% and that of the micrinite 94%. For both macerals, vitrinite is the main impurity. Since the vitrinite has a petrographi-cal purity of 99%, it is not difficult to calculate the values for the pure exinite and pure micrinite from the experimental data on the highly enriched maceral fractions. All values reported in the tables are corrected ones. Table I summarizes the results of elementary analysis (maf) and the percentage of volatile matter. 

The individual coal constituents contribute different portions to the volatile matter of the coals (5). With increased stratification, the volatile matter decreases, caused by the relative distribution of the various maceral groups. 

When the concentrates of macerals of a high-volatile bituminous coal were irradiated with 6-J pulses from a ruby laser the total gas yield varied directly with volatile matter (13.4—55.4 rtiaf%) of the macerals273). Major gases evolved were H2, CO and C2 H2 their relative concentrations varied little among the macerals. 

The properties of coal are affected by the composition of the coal. Furthermore, the natural constituents of coal can be divided into two groups (1) the organic fraction, which can be further subdivided into microscopically identifiable macerals and (2) the inorganic fraction, which is commonly identified as ash subsequent to combustion. The rank (thermal maturity) of the organic fraction of the coal is determined by the burial depth (pressure) and tanperature. The composition of organic (non-mineral) fraction changes with rank with the main indicators of rank bringing the reflectance of the vitrinite, carbon, and volatile matter content on a dry ash-free basis. 

For example, as the carbon content of the coal increases, the active thermal decomposition occurs in successively higher temperature ranges and the maximum weight loss decreases quite substantially (Figure 13.10). In addition, different macerals in any one particular coal also generate different amounts of volatile matter, and, thus, similar trends are noted when exinites, vitrinites, and inertinites of the same rank are thermally decomposed (Figure 13.11). 

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