Lignite devolatilization

Anthony et al. [10] studied rapid devolatilization of monolayers of lignite and bituminous coals supported on wire mesh heating elements in helium. They calculated... 

Replacing the product of k cxp(-EIRT) in Equation 11.48 by Equation 11.50, we have the overall reaction rate that would be observed at temperature T, to which the coal is assumed to be heated at constant rate m from the initial temperature T0. For devolatilization of Montana lignite, k0 = 1.07 x 1010 s-1, E0 = 48.72 kcal/mol, and o = 9.38 kcal/mol. 

The process is also adaptable to similar uses with other feed materials for example, the devolatilization of coal and lignites. 

A schematic flowsheet of the C02 acceptor process is shown in Figure 1. Since we are concerned here with only the gasifier and regenerator sections, only these are shown. Lignite drying, devolatilization, gas purification, and methanation steps are omitted. 

An acceptor life study in the continuous unit was carried out as follows. An inventory of fresh acceptor, usually 16 X 28 mesh, was established in the regenerator while an inventory of 35 X 150 mesh devolatilized lignite char was established in the gasifier. The operating pressure was normally set at 300 p.s.i.a. The regenerator was heated to the desired temperature (usually 1910°-1940°F.) while fluidized with... 

Acceptor 16 X 28 mesh Tymochtee dolomite Char 35 X 150 mesh devolatilized lignite char System pressure, 20 atm. 

In contrast to the results obtained with bituminous coals, the weight-loss curve of subbituminous coal exhibited no peak instead, it reached a plateau in Figure 2. From 800° to 1000°C the volatile yield remained level at about 42 wt % of the coal. Beyond this region the production of volatiles increased sharply. The fact that the devolatilization curve of subbituminous A coal differs distinctly from those of bituminous coals indicates a need for further study of other subbituminous coals and lignites. Low rank materials such as these are of interest in coal gasification because their reserves are abundant and because they are situated in deposits with shallow ground cover. 

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