Steam gasification of almond shells in a fluidised bed reactor: the influence of temperature and particle size on product yield and distribution

The steam gasification of ground almond shells has been carried out in a continuous, bench scale, fluidised bed reactor in order to evaluate the effects of particle size and operating temperature on the product yield and distribution. The mean particle size was varied from nearly 300 μm to over 1 mm and the bed temperature from 600 to 800°C. The results reveal that for smaller particle sizes differences in product yield and distribution practically disappear as the higher temperature bound is approached, whereas for particles above 1 mm in diameter the yield continues to increase over the entire temperature range, never reaching that attained by the smaller particle systems. This behaviour is indicative of the increasing significance of extra- and/or intra-particle heat transfer limitations with increasing particle size.