Abstract

Rice husks were processed in a laboratory-scale fluidized bed reactor with a SiC bed. With the objective of smaller reactor volumes and lower operational costs in scale-up, elevated feed rates of ca. 875 g/h were explored, equivalent to feed rate per area of 35 kg/m² min and carrier gas to biomass ratios of 0.8 wt/wt. Temperatures of 450, 525, and 600 °C, and SiC bed heights of 4.9 and 6.5 cm were tested. Experiments with a sand bed, a poorer heat conductor than SiC, were conducted as well. In these high feed rate conditions, a maximum organic phase yield of 31 wt% was obtained at the highest temperature of 600 °C and 6.5 cm of bed, 20% volatile content remained in the product char. Experiments with sand bed elucidated that the heat transfer bottleneck is the conduction step inside biomass particles. Higher inert bed heights are suggested to increase biomass particle residence time in the dense sand bed, achieving better devolatilization and lower temperatures. Finally, a scale-up analysis with extrapolated lab-scale results shows that operating with a high feed-rate per area, as demonstrated, could lead to reactor volumes six times smaller than other reported points, being more suitable for mobile units.

摘要

稻壳在实验室规模的带有 SiC 床的流化床反应器中进行处理。为了缩小反应器体积和降低放大操作成本，将进料速率提高约。探索了 875 g/h，相当于每面积 35 kg/m ^{2 的}进料速率min 和载气与生物质的比率为 0.8 wt/wt。测试了 450、525 和 600 °C 的温度，以及 4.9 和 6.5 cm 的 SiC 床层高度。还进行了沙床实验，沙床是比 SiC 更差的热导体。在这些高进料速率条件下，在 600 °C 的最高温度和 6.5 cm 的床中获得了 31 wt% 的最大有机相产率，20% 的挥发分留在产物炭中。沙床实验表明，传热瓶颈是生物质颗粒内部的传导步骤。建议使用更高的惰性床高度以增加生物质颗粒在致密砂床中的停留时间，从而实现更好的脱挥发分和更低的温度。最后，具有外推实验室规模结果的放大分析表明，如证明的那样，在单位面积的高进给速率下运行，