Impacts of slurry and dry forms of low-rank coal (lignite) on quality of syngas produced

Gasification is one of the prominent and technically efficient technologies for converting solids like coal, biomass or solid waste into useful gas known as “syngas.” Several configurations are in use today among which entrained flow gasifiers have several advantages over other configurations. Presently research is more focused on micro-level modifications in the configurations which have a significant impact on overall performance of gasification. Scant, literature is available for comparison of slurry over dry form of feedstocks, especially with low-grade coals. Hence, present research aims to establish a concrete finding regarding the impacts of slurry versus the dry condition of coal on the overall performance of gasification. To achieve this goal, a two-dimensional computational fluid dynamic (CFD) model of downdraft gasifier was developed in commercial CFD software FLUENT for performing numerical simulations with indigenous coal feedstock. Rich oxidant conditions (95% oxygen and 5% nitrogen) were maintained in the gasifier for the gasification. The performance of gasification was measured by comparing efficiencies of gasification and the quality of syngas produced with different coal forms. As per simulation results, coal forms and operating conditions caused a significant effect on overall gasification performance. In syngas composition, H₂ mol fraction reached at maximum, when the slurry form of coal was used for gasification. This effect is remarkable for generating hydrogen-rich fuel from lignite without consuming steam externally.