BORAH , R C and GHOSH , PALLAB and Rao, P G
(2008)
Devolatilization of coals of North-Eastern India under fluidized bed conditions in oxygen-enriched air.
Fuel Processing Technology, 89 (12).
pp. 1470-1478.
Abstract
Oxygen-enriched air can increase the combustion efficiency, boiler efficiency, and sulfur
absorption efficiency of atmospheric fluidized bed combustion (AFBC) boilers which use
high-sulfur coal, and other combustion systems that use coal. Devolatilization is the first
step in the gasification or combustion of coal. In this work, devolatilization characteristics of
five run-of-mine (ROM) coals of North-Eastern India having particle-size between 4mmand
9 mm are reported. The experiments were performed under fluidized bed conditions at
1123 K in enriched air containing 30% oxygen. The devolatilization time was correlated with
the particle diameter by a power law correlation. The variation of mass with time was
correlated by an exponential correlation. It was observed that the average ratio of yield of
volatile matter to the proximate volatile matter decreased with the increase in volatilecontent
of the coals. A shrinking-core model was used to determine the role of filmdiffusion,
ash-diffusion and chemical reaction. The experimental results indicate the
likelihood of film-diffusion to be the rate-controlling mechanism in presence of oxygenenriched
air. A cost-analysis was carried out to study the economy of the process
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