Determination of Coke Properties

Tests for coke characteristics can be divided into two major classes chemical and physical. Considering chemical tests first, there are ultimate analysis and proximate analysis for the coke. Another chemical property, reactivity, which refers to the ability of coke to react with carbon dioxide, has also been proposed (Schapiro and Gray, 1963 Miller et al., 1965 Rao and Jalon, 1972 Daly and Budge, 1974) the ASTM does not provide a standard reactivity test procedure. 

The physical properties of coke can be categorized into three groups (1) the static properties considered for a lump of coke (porosity), (2) the static properties of bulk coke (specific gravity, bulk density, and size), and (3) the mechanical properties (shatter, stability and hardness, and high-temperature strength). 

Coke pore structure includes pores on the external surface of the lump, internal microscopic pores, and submicroscopic pores, whose diameters are only several Angstrom units (10 m) (Dahme, 1953 Thompson et al., 1971). The calculation of porosity can be made with a knowledge of the apparent specific gravity and the true specific gravity. 

Apparent specific gravify is the average weight per unit volume (relative to water) of individual lumps of coke, and so includes the effect of porosity. True specific gravity is the average weight per unit volume (relative to water) of individual particles of coke, and is measured on a crushed sample to eliminate the effect of porosity. 

The usual method for measuring coke strength (resistance to abrasion and impact) is by measuring the size degradation that occurs in a tumbler drum. The different drum tests were devised to maximize the measurement in degradation between various cokes. 

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