Thermal coal conversion

The devolatilization process is common to all thermal coal conversion processes and several papers have reported the results of many years of research (Anthony and Howard, 1975 Juntgen and van Heek, 1979). Coal consists of many organic molecules bound together through relatively weak carbon-carbon bonds. Many of these bonds tend to break at low temperatures (about 350°C), releasing aromatic hydrocarbons and gases. 

Synthesis gas is obtained either from methane reforming or from coal gasification (see Coal conversion processes). Telescoping the methanol carbonylation into an esterification scheme furnishes methyl acetate directly. Thermal decomposition of methyl acetate yields carbon and acetic anhydride,... 

Coal can be converted to gas by several routes (2,6—11), but often a particular process is a combination of options chosen on the basis of the product desired, ie, low, medium, or high heat-value gas. In a very general sense, coal gas is the term appHed to the mixture of gaseous constituents that are produced during the thermal decomposition of coal at temperatures in excess of 500°C (>930°F), often in the absence of oxygen (air) (see Coal CONVERSION PROCESSES, gasification) (3). A soHd residue (coke, char), tars, and other Hquids are also produced in the process ... 

Goal Processing to Synthetic Fuels and Other Products. The primary approaches to coal processing or coal conversion are thermal decomposition, including pyrolysis or carbonization (5,6), gasification (6), and Hquefaction by hydrogenation (6). The hydrogenation of coal is not currently practiced commercially. 

Pyrolysis. In this context it is relevant to consider initially the effect of hydrogen contents on tar yields during pyrolysis (carbonization). This is particularly so, since, in all coal conversion processes little happens until the coal is at a temperature above that where active thermal decomposition normally sets in. In other words, all coal conversion processes may be regarded as pyrolysis under a variety of conditions which determine the nature of the primary decomposition and the reactions which follow. 

This paper touches on the chemistry of coal gasification and liquefaction comments on the current status of conversion processes and the influence of coal properties on coal performance in such processes and examines the contributions which coal conversion could make towards attainment of Canadian energy self-sufficiency. Particular attention is directed to a possible role for the medium-btu gas in long-term supply of fuel gas to residential and industrial consumers to linkages between partial conversion and thermal generation of electric energy and to coproduction of certain petrochemicals, fuel gas and liquid hydrocarbons by carbon monoxide hydrogenation. 

During coal conversion, the coal structure influences both thermal and catalytic reactions. Thermal reactions of solid coals initiate the breakage of weak bonds at rates proportional to their bond dissociation energies. The radicals thus produced require stabilization by hydrogenation or addition of small molecules otherwise the radicals couple to produce much more thermally stable bonds, which eventually leads finally to the formation of infusible and insoluble coke. 

Coal hydropyrolysis is defined as pyrolysis under hydrogen pressure and involves the thermal decomposition of coal macerals followed by evolution and cracking of volatiles in the hydrogen. It is generally agreed that the presence of hydrogen during the pyrolysis increases overall coal conversion. (, )... 

The electricity-generating ability of the present-day gas turbine is limited by the temperature of the inlet gases. The maximum allowable operating temperature today is in the 1900-2000°F range and is governed by the thermal tolerance of the turbine construction metal. The values shown in Table IX indicate the effect that changes in this gas temperature will have on the overall process efficiency of the coal conversion processes. Figure 8 also illustrates this effect. 

Thermodynamic Analysis of Coal Conversion in Thermal Plasma... 

Kinetic Analysis of Thermal Plasma Conversion of Coal Kinetic Features of the Major Phases of Coal Conversion in Plasma... 

THERMAL AND NON-THERMAL PLASMA-CHEMICAL SYSTEMS FOR COAL CONVERSION... 

Coal Conversion in Low-Pressure Glow and Other Strongly Non-Equilibrium Non-Thermal Discharges... 

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