Volatile matter content

The volatile matter provides the percentage of volatile products that are released from the coal under rigidly controlled conditions, excluding the moisture vapor. The empirical test is a small-scale pyrolysis assay depending on typical parameters such as grain size, heating rate, end temperature, and gas atmosphere. The type, size, and shape of the heating equipment must be selected carefully because of the influence on the heat rate, which can easily cause 1-3%-points in difference. 

A common procedure (DIN 51720 [26]) starts with the preparation of Ig of coal in a quartz crucible that is covered with a resting lid. The crucible is put into a 900 °C preheated muffle furnace for exactly 7 min. The sample is taken out, cooled, and subsequently weighed. The weight loss corrected by the moisture content equals the volatile matter. Other methods (ASTM D3175 [27], ISO 562 [28]) use platinum crucibles and 950 °C. 

The residue in the crucible is coke, which is also characterized in some national standards by color, luster, swelling, Assuring, structure, surface, and hardness. The coal is classified as agglomerating if the remaining char button is capable of supporting a 500-g weight without pulverization or if it shows clear swelling or cell structure [10,29]. 

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Thermal Heat content Ash content Halogen content Moisture content Heavy metal content Volatile matter content... 

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. 

The nature of coke varies somewhat throughout the coke drum. In the lower section, the coke is dense and the volatile matter content is low. At the higher levels the coke becomes softer, more brittle, and the volatile matter content increases. The volatile matter in the coke at the top of the drum may be 2 to 3% higher than in the coke from the bottom of the drum (15). 

Figure 4. Relation between Volatile Matter Content and Other Properties of Petroleum...

Drying. The solvent is removed from the cordite by drying at temperatures of 38-43°C for several days to a volatile matter content of 0.4-0.6%. The drying time depends on the thickness of the powder cords. Cordite MD loses its solvent more easily than cordite Mk I and therefore dries more quickly. 

Previous investigations (14, 15) have shown that R° increases as the fixed carbon content increases and decreases as the volatile matter content increases. The relation of R to volatile matter for coals included here is similar to that reported by other investigators (14, 15) a progressive increase in R is accompanied by a corresponding decrease in volatile matter content, as shown in Figure 1. 

Others have related fixed carbon and volatile matter content to calorific value (4, 5) and FSI (12). However, we found that reflectance correlated better with these chemical properties (r = 0.95 and 0.87, respectively). Figure 2 shows the relationship between R. and calorific value for the coals in this study. In general the calorific value increases sharply with increases in R. in the 0.5-1.1% range, increases slightly in the 1.1-1.7 R range, then levels off... 

Since R is related to volatile matter content (Figure 1), it would be reasonable to expect a correlation between this rank parameter and specific properties of by-product gas. Our results show that gas specific gravity and gas heating value can, in fact, be estimated fairly accurately from reflectance data. 

This investigation shows that the average reflectance of vitrinite in coal (Ro) can be used to estimate carbonization product yields, by-product gas properties, chemical properties, oxidation effects, and combustion behavior. Moreover, R along with calorific value and volatile matter content might be employed to classify accurately and consistently coals of all ranks. 

Analyses of Anthracites Used. For most of the experimental work an anthracite from the St. Nicholas breaker was used. Its proximate analysis (dry basis) was as follows C, 84.3% V.M., 4.5% ash, 11.2%. Anthracites from other breakers used in this program had the following volatile matter contents... 

Generally, the decrepitation resistance of anthracites increases with decreasing volatile matter content, but in some cases differences in physical properties of the coals appear to nullify this relation. 

H. R. Linden High temperature pyrolysis of coal with high energy sources seems to follow readily predictable paths similar to hydrocarbon pyrolysis. The effects of pressure, gas atmosphere, reaction time, and the volatile matter" content of the coal bear the same relationship to yields of methane, ethane, ethylene, acetylene, and hydrogen as for simple hydrocarbons. Effective reaction temperature, although not directly measurable, could be estimated by means of a suitable chemical thermometer, such as the C-. H-. -C. H4-H. system which approaches equilibrium very rapidly. As Dr. Given also noted, equating the volatile matter" to the reactive portion of the coal is an oversimplification but adequate for empirical purposes the C H ratio of the coal would probably be more suitable. 

By weighing the first and last passes, the mill homogenization procedure is also use to measure volatile matter content. Samples are then allocated to such tests as are required in accordance with ISO methods. In particular, it is specified that volatile matter is measured according to the oven method of ISO 24813. Apparently, we have two measures of volatile matter Mooney viscosity and plasticity retention index are measured as discussed later in the chapter. Although the title and the procedure indicate that the method is intended for raw rubber, it is also specified that vulcanization characteristics are measured. 

Proximate analysis, determination of moisture content of the general analysis sample of coke Proximate analysis, determination of volatile matter content Proximate analysis, determination of ash content Determination of gross calorific value Ultimate analysis of coal and coke, determination of carbon and hydrogen content, high temperature combustion method Liebig method... 

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