Hydrogen rich syngas production from oxy-steam gasification of a lignite coal - A design and optimization study

The hydrogen levels in the syngas were examined as a function of oxygen, coal and steam flow rates. A maximum hydrogen concentration of 50% (dry-basis) was achieved at low oxygen to carbon ratios and the cold gas efficiencies were in the range 80-90%. The observed experimental trends in syngas compositions and cold gas efficiencies were reasonably well represented by the CFD simulations and compared favorably with data obtained from a transport reactor integrated gasification system. Simulations predicted that the major product gases at the reactor outlet were close to their equilibrium levels. The decrease in hydrogen concentrations in the syngas at high oxygen and steam flow rates resulted from changes in the oxidation reaction rates, hydrodynamics and steam levels. The levels of steam were attaining saturation conditions.