Characteristics of coals

The organic chemical structural types believed to be characteristic of coals include complex polycyclic aromatic ring systems with connecting bridges and varied oxygen-, sulfur-, and nitrogen-containing functionalities. 

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. 

TABLE I. Structural Characteristics of Coal Fractions Separated from Solubilized... 

The characteristics of coals that determine classification and suitability for given applications are the proportions of volatile matter, fixed carbon, moisture, sulfur, and ash. 

Typical operating characteristics of coal gasifiers are as follows ... 

No reliable data have been gathered for the wastewater characteristics of coal pile runoff. Example 3 (Section 13.6.3) presents the technical information on the characteristics of a combined wastewater (consisting of coal pile runoff, regeneration wastewater, and fly ash), and its treated effluent. 

The disposal of coal combustion residues must take into account the nature and amount of the products to be disposed, as well as the nature of the disposal environment. It is a characteristic of coal utilization that many historic wastes exist that lack, or almost totally lack, characterization data. Only in recent decades, with concern over the environmental impacts of present and future accumulation of wastes, have characterization studies been made. The principal types of waste are described in Table 5. 

Previously it had been thought that combustion characteristics of coals could be determined only from actual tests (6). However, testing in a full... 

Explosibility characteristics of coal dust clouds using... 

Determination of the washability characteristics of coal by the float and sink (float-sink) method can be applied to coal of any particle size provided suitably large vessels to hold the larger lumps are available. Air-dried coal, not dry coal, should be used since the separation depends partly on the difference in specific gravity of the clean coal and dirt particles, and the specific gravity, in turn, is dependent on the moisture content of the coal. If the coal is dried before the test is carried out, the conditions will then differ from those in commercial washers, and the results will be at variance with those obtained in practice. 

ASTM D-4371. Standard Test Method for Determining the Washability Characteristics of Coal. 

The theology (deformation and flow) of coal has been studied in an effort to apply it to characteristics of coal in coal mines coal elasticity (quality of regaining original shape after deformation under strain) has also been studied. However, it may be quite difficult to obtain meaningful measurements of coal elasticity. For... 

Coke button button-shaped piece of coke resulting from a standard laboratory test that indicates the coking or free-swelling characteristics of coal a coke button is usually expressed in numbers from 1 to 9, representing the size of the coke as compared to a standard the more a coal swells and cokes, the higher the number assigned to it. 

Test Method for Determining the Washability Characteristics of Coal," Method D 4371, Annual Book of ASTM Standards. Vol. 5.05, Amer. Soc. for Testing and Materials, Philadelphia, PA, 1988. 

Overall, the consensus of the participants 1s that any of the six coal derived liquids could be considered as an acceptable replacement for liquid petroleum fuel 1n either Plant Sweatt boiler with no equipment modifications, equipment additions or environmental variances. The application or replacement usage of these coal derived liquids 1n other utility boilers would not seem to be any more difficult but should be prefaced by an extensive, Individual site assessment of candidate units. The few modifications required at Plant Sweatt Indicate that a limited number of design criteria would be affected 1f these six synthetic liquids were to be Included 1n the fuel specifications of future utility boilers. The handling and emission characteristics of coal derived liquids may even be preferable to certain petroleum liquids 1n some utility applications. 

Our goal is to gradually replace all coal and fossil fuel power plants with renewable energy ones, but while they exist (and probably will for most of this century), it is very important to reduce the damage they cause by optimizing their operation. In the United States, there are about 1000 coal preparation plants and coal-fired power plants. One key consideration in operating coalburning facilities is the control of C02 and sulfur dioxide (S02) emissions to the atmosphere. The characteristics of coal are monitored for environmental protection, quality assurance, and process control purposes. 

The major question involving burning characteristics of coal liquids relates to the higher nitrogen content compared to petroleum fuel oils and the potential effect on NO emissions. Since NO emissions are sensitive to burning conditions, however, actual burning tests are required under various conditions to assess the effects. 

Characteristics of Coal-Derived Liquids from Different Processes ... 

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