SLAGGING FIXED-BED GASIFIER FOR LIGNITE.

Test results are described in gasifying lignites in a pilot plant, slagging, fixed-bed gasifier located at the U. S. Department of Energy (DOE) Grand Forks Energy Technology Center (GFETC), Grand Forks, North Dakota. The oxygen-fueled unit operates at pressures up to 400 psig (2,758 kPa). It differs from the commercial dry-bottom gasifier in its method of ash removal. In a dry-bottom process, excess steam is added through a grate, which prevents the ash from slagging. The steam input is reduced to obtain the high temperatures desired to produce a molten ash or slag. As a consequence an increase of 3 to 5 times in gas production per unit bed area is experienced in comparison to a dry-bottom unit. In addition, the amount of liquid effluent produced is significantly reduced. The GFETC slagging gasifier, which has a nominal capacity of 25 ton/day (22,675 kg/d), was designed and operated in the period from 1959 to 1965 to establish operability of the slagging method of ash discharge and to evaluate process parameters.