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Coal rank properties

Properties Involving Utilization. Coal rank is the most important single property for appHcation of coal. Rank sets limits on many properties such as volatile matter, calorific value, and swelling and coking characteristics. Other properties of significance include grindabHity, ash content and composition, and sulfur content. [Pg.222]

ABSTRACT CO2-ECBM Micro-Pilots have been carried out in Canada and China to assess the response of low- and high-rank coal reservoirs to C02 injection. The selectivity of coals for C02, compared to methane, can vary from 10 to 1 depending on coal rank. Although the C02 is more efficiently stripped by coals of low rank, permeability impairment is greater and the amount of methane recovered is less than for high-rank coals, providing other reservoir properties are similar. If a pure C02 source is not available, N2-C02 mixtures may produce more favourable economics. [Pg.147]

Each of the four coals that were studied exhibited similar behavior, and in each case the three properties passed through early maximum values. Independent of the coal or the measured property, the maxima all occurred between 5-10% wt extract yield and the subsequent decreases were arrested between 20-35% extract yield. No distinction could be made on the basis of coal rank although, admittedly, the number of coals is small. [Pg.78]

Pressure of the overburden does not cause chemical reactions which lead to a higher rank. Experiments have shown that static pressure even retards coalification processes. By contrast, pressure affects the physical properties, notably the porosity and moisture content in low rank coals. Further, the optical anisotropy of vitrinites (which is a tension anisotropy) is caused by pressure. Shearing movements have influenced the chemical coalification only occasionally and locally in the foredeeps that we have studied (for instance in the immediate vicinity of overthrusts). In such cases the tectonic movements probably were so quick that the friction heat and the shearing could operate. Shearing in no way can account for the gradual increase in coal rank with depth. [Pg.156]

In ordar to determine the effect of coal rank (at established by reflectance measurement of vitrinite in coal) on the reactions of coal as related to carbonization, gasification, combustion, and other processes, a wide range of bituminous coals were studied. The results show that reflectance measurements can be used effectively (1) to determine accurately yields of coal carbonization products such as coke, tar, gas, light oil, and liquor from pilot and commercial coke oven (2) to obtain the heating value and specific gravity properties of gases from these processes (3) to determine the free swelling index and B.t.u. content of coals ... [Pg.570]

Quring the past several years coal petrography has gained acceptance in certain areas of coal utilization, preparation, and mining as a useful analytical tool. The rapid evolution of this analytical technique can be attributed to the development and subsequent refinement of quantitative methods for measuring the reflectance characteristics of vitrinite in coal (8, 14, 15, 16). Mean maximum reflectance has been shown to be directly related to coal rank (14, 16). Moreover, it is known that rank is important in determining certain carbonization and chemical properties. [Pg.570]

The dielectric constant varies with coal rank (Chatterjee and Misra, 1989). The theorem that the dielectric constant is equal to the square of the refractive index (which is valid for nonconducting, nonpolar substances) holds only for coal at the minimum dielectric constant. The decreasing value of dielectric constant with rank may be due to the loss of polar functional groups (such as hydroxyl or carboxylic acid functions), but the role of the presence of polarizable electrons (associated with condensed aromatic systems) is not fully known. It also appears that the presence of intrinsic water in coal has a strong influence on the dielectric properties (Chatterjee and Misra, 1989). [Pg.126]

Rank property of coal that is descriptive of degree of coalification (i.e., the stage of metamorphosis of the original vegetal material in the increasing sequence peat, lignite, subbituminous, bituminous, and anthracite) (ASTM D-388). Anthracite rank of coal such that on a dry, mineral-matter-free basis, the volatile matter content of the coal is greater than 2% but equal to or less... [Pg.206]

There have been a large number of electron spin resonance (ESR) studies of coal and coal products,(1J but a microscopic interpretation of the resulting data has been hampered by the chemical heterogeneity of the coal samples examined. While several surveys of specially selected macerals have appeared, 3), the recent evolution of maceral separation techniques - now allows detailed ESR observations to be made on coals systematically fractionated in which coal rank, maceral type, and maceral density are simultaneously distinguished. The present report surveys the behavior of a variety of ESR properties of carbon radicals in exinite, vitrinite, and inertinite macerals in a variety of coals of different rank. These data... [Pg.124]

Rubio, B. and Izquierdo, M.T. (1997). Influence of low-rank coal char properties on their SO2 removal capcity from flue gases I non-activated chars. Carbon, 35, 100-11. [Pg.561]

TABLE III Major Fuel Properties as Deteimined by Standardized Analyses for Typical Samples of Each Major Coal Rank... [Pg.111]

Furthermore, it is worthy of note here that coal rank is often equated directly to carbon content. Even though this may acmaUy appear to be the case, classification of coal by rank is a progression fron high-carbon coal to low-carbon coal (or vice versa) but this is in conjunction with other properties of the coal. [Pg.47]

For example, certain physical properties of coal (which are themselves a function of coal rank) change with the depth of burial (Figure 3.23) (Breger, 1958 Francis, 1961 Schmidt, 1979) but it should be noted here that the temperature gradient is, of course, influenced by the thermal conductivity of the rocks, which essentially makes comparisons of coals from different locales extremely... [Pg.90]

Although coal rank plays an important role in defining coal use, coal type and coal grade are also extremely important consideration (Table 4.12). These parameters are the primary factors that influence a coal s specific physical and chemical properties and these properties in turn determine the overall quality of the coal and its suitability for specific purposes. [Pg.122]

Coal rank from the petrographic point of view is commonly expressed in terms of vitrinite reflectance which may act as an indicator that is independent of other factors (e.g., coal type or grade). Unlike other chemical parameters (e.g., carbon content, hydrogen content, volatile matter yield, and calorific value) it is not dependent on the overall composition of the coal. A number of coal properties progressively change with the advance in rank and the rank of a coal is therefore a major factor influencing its potential application. [Pg.124]

The direct objectives of coal cleaning practices are reduction (within predetermined limits) of size, moisture, ash, as well as sulfur (Williams, 1981 Couch, 1991). However, coal properties have a direct bearing not only on whether but also on how coal should be cleaned. Indeed, coal rank (rank being a complex property that is descriptive of the nature of the coal and its properties) (Chapters 2, 8, and 9) can, and usually does, play an important role in determining the feasibility and the extent of cleaning. [Pg.155]

Therefore, for the molecular structure of coal, we should accept and adopt the view of an average molecular structure to build coal molecule structures, which might not represent the entire coal structure, but model one or several aspects of coal [27]. Furthermore, when we construct a suite of concrete models aiming at different coal ranks and coal types related to the practical reaction processes, we are convinced that the models constructed by the above principles are reasonable, exact, and scientific. They can give a reasonable microscopic description, reflect the properties of coal in one or several aspects, and provide reasonable microscopic explanation for the particular and local macroscopic property [28]. [Pg.241]

The maceral content defines the coal type sapropelic, with >50% liptinite, or humic, more abundant, usually presenting a banded structure. On the other hand, based on the different optical properties of macerals, the reflectance of vitrinite is an essential characteristic used in coal identification and related to rank. A good analysis of maceral content provides knowledge about the chemical composition of a coal, their behavior in different conversion processes, and can also be used as a parameter of coal rank (see section on Petrographic analysis). [Pg.760]

Martyniuk, H., and Wieckowska, J., The effect of coal rank and carbonization temperature on sulphur dioxide adsorption properties of coal chars. Fuel. 76(7). 563-566 (1997). [Pg.1031]

Extents of coalification (coal rank) are usually measured in terms of carbon and volatile contents as well as reflectance measurements, the latter being a direct indicator of extents of aromaticity in the coal (Table 2.1). Coalification (rank) has proceeded continuously without discontinuities in terms of analytical data. Some physical properties, however, have not developed continuously. Fluidity (plasticity), an important industrial property, rises and falls with increasing coal rank. On heating coals in an inert atmosphere, fluidity increases from zero at 81 wt% carbon, reaching a maximum at about 87 wt% carbon, falling to zero at about 91 wt% carbon (Figure 2.24). [Pg.36]


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See also in sourсe #XX -- [ Pg.42 ]




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