Effects of gasifier selection on overall plant costs for a large low-Btu gas application. [Two-stage fixed-bed gasifier; Winkler fluidized-bed gasifier; Rockwell molten-salt gasifier]

This report presents the results of a study comparing different gasifiers as a fuel gas source for an iron-ore pelletizing facility. The objective of this study was to develop and compare the technical and economic aspects of several systems. Systems involving three different gasifiers, the two-stage fixed-bed gasifier, the Winkler fluidized-bed gasifier, and the Rockwell molten-salt gasifier, were examined. In each case, the fuel gas product was a clean, low-Btu gas produced at approximately atmospheric pressure and supplied to the pelletizing facility at a rate of 20 billion Btu per day. The evaluations were based on installing the gasifiers at an existing Erie Mining Company iron-ore pelletizing plant at Hoyt Lakes, Minnesota. Thus, the designs that were developed incorporated existing facilities whenever possible. The designs presented were technically feasible. Estimated fuel gas costs ranged from $7.70 per million Btu (Winkler case) to $10.20 per million Btu (Rockwell case). In all cases, the fuel costs were higher than the current price of natural gas at Hoyt Lakes, $3.52 per million Btu. Not included in the study were considerations of intrinsic factors, such as the interruptible nature of the natural gas supplies and future anticipated changes in the prices of natural gasmore » and coal.« less