A small-scale fluidized bed steam gasification system has been built and operated as part of a USDOE-supported program to provide technical support for commercial demonstrations of this technology. The gasification system has been operated under a variety of conditions and is able to achieve better carbon conversion than reported in the full-scale systems. Analysis of the heterogeneous carbon-steam gasification reaction indicates that the rate of conversion achieved in the fluidized bed systems is less than that reported for steam gasification of black liquor char, which is likely a consequence of physical differences, particularly internal surface areas, of these materials. The product gas is at equilibrium with regard to the water-gas shift reaction, indicating that the bed itself strongly catalyzes this reaction. Adding air to the fluidizing steam did not cause local heating or agglomeration of the bed, but did decrease product gas quality (heating value) and allowed the bed heaters to operate at lower temperature.
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