Gasification Characteristics of Lignite in a Fluidized Bed Gasifier

Abstract

Steam gasification experiment of lignite was carried out in a fluidized-bed gasifier, Effects of bed temperature, steam flow rate and particle size on the gasification behaviors were explored. Gasification behaviors of lignite with/without minerals were compared. When the bed temperature increased, the carbon conversion and gasification efficiency increased, H2 and CO Content increased, CO2 content decreased, and CH4 content kept essentially unchanged. When steam flow increased, the carbon conversion, gas yield and gasification efficiency increased, the content of H2, CO and CO2 in the syngas increased while the CH4 content decreased. In this experiment, compared to the bed temperature and the steam flow, particle size showed only slightly influence on the gasification process. After removing the minerals, weight loss of lignite sample was almost same as the raw lignite, but the pyrolysis rate of the lignite with no minerals accelerated. In the experiment, although the carbon conversion kept no change, the content of H2 and CO2 decreased, CO content increased and CH4 content fallen slightly. From the above, the inherent minerals in the lignite showed a positive influence on the gasification process, which improved the composition of the syngas.