Characteristics and Mechanisms of Gaseous Organic Compound Generation during Coking

Abstract

Five representative coal samples used for coking were carbonized in a thermogravimetric analyzer to simulate an industrial coking process. The gaseous organic compounds generated were analyzed with a coupled mass spectrometer. During coal carbonization, thermal detachment of aliphatic side groups causes disintegration of the coal structure. Methyl groups detach at higher temperatures than methylene and methine groups, and the temperatures corresponding to peak generation of these groups increase with the metamorphic grade of the coal. Methane is generated by three mechanisms: below 370 °C, methane adsorbed in coal is thermally released; at about 510 °C, methyl groups are thermally detached from the coal to form CH3+ ions, which further combine with hydrogen to form methane; finally, at about 720 °C, methane is produced as a result of the condensation of aromatic rings to form larger fused rings. Benzene is also generated by three mechanisms: at 400–500 °C, aromatic structures in coal lose side groups (e.g. methylene or methine) to form benzene ions, which subsequently react with hydrogen to form benzene; at 500–700 °C, benzyl structures in coal lose methyl groups to form benzene ions, which then combine with hydrogen to form benzene; finally, at about 800 °C, condensation of fragments in coal also forms benzene.

Analysis of metamorphism and tendency of black coals to spontaneous combustion

“…Similar results ( Fig. 3) are obtained by processing other experimental data [19][20][21][22][23][24][25][26]. This indicates a different transformative effect of pressure, temperature, and time factors at individual stages of metamorphism.…”

“…1, c). TECHNOLOGY [19][20][21][22][23][24][25][26]: а -the ratio between the carbon content and a mixture of other components (О 0 , Н 0 , N 0 ); b -the ratio between the content of carbon and oxygen; c -the ratio between the content of carbon and hydrogen; d -the ratio between the carbon content and nitrogen; I, II, III, IV -ranges of changes in the properties of coal; 1 -linear interpolation of experimental data; 2 -the boundaries of the change in components; • -experimental data…”

“…The interdependence of the content of hydrogen (H 0 ) and oxygen (O 0 ) in the organic (combustible) mass of coal according to[19][20][21][22][23][24][25][26] : 1 -the boundaries of the change in the considered parameters; • -experimental data…”

On the possibilities to apply indices of industrial coal-rank classification to determine hazardous characteristics of workable beds

“…Classification parameters, being typical for the whole range of coal metamorphism degree, have been analyzed. The parameters are as follows: the basic components of organic mass [8]- [10]; weight and volume yields of airtight coal thermal decomposition products [11], [12]; moisture content [13], [14]; thermal power [15]; mechanical strength [16]- [18] etc.…”