Pulsation-assisted fluidized bed for the fluidization of easily agglomerated particles with wide size distributions

Experimental and drying kinetics study on millet particles by a pulsating fluidized bed dryer

This research studies experimentally the drying of foxtail millet in a pulsation-assisted fluidized bed. The effects of temperature and pulsating flow frequency on millet drying are examined. The experiments are conducted at temperatures of 40 °C, 50 °C, and 60 °C for three pulsating frequencies of 0.5, 1, and 2.5 Hz and continuous flow. The best result is obtained for drying with a frequency of 1 Hz. It shows that the pulsating flow is more effective at 50 °C as compared to other temperatures. Four reliable semi-empirical models are used for predicting the moisture reduction during drying process. Among the fitted dynamic models, the model that has the maximum correlation coefficient (R 2 ) and minimum sum of squares of error (SSE) and root mean squared error (RMSE) and well able to predict the behavior of millet drying in the whole process was chosen.

Effect of Inlet Flow Strategies on the Dynamics of Pulsed Fluidized Bed of Nanopowder

The use of fluidization assistance can greatly enhance the fluidization hydrodynamics of powders that exhibit poor fluidization behavior. Compared to other assistance techniques, pulsed flow assistance is a promising technique for improving conventional fluidization because of its energy efficiency and ease of process implementation. However, the inlet flow configuration of pulsed flow can significantly affect the bed hydrodynamics. In this study, the conventional single drainage (SD) flow strategy was modified to purge the primary flow during the non-flow period of the pulse to eliminate pressure buildup in the inlet flow line while providing a second drainage path to the residual gas. The bed dynamics for both cases, namely, single drainage (SD) and modified double drainage (MDD), were carefully monitored by recording the overall and local pressure drop transients in different bed regions at two widely different pulsation frequencies of 0.05 and 0.25 Hz. The MDD strategy led to substantially faster bed dynamics and greater frictional pressure drop in lower bed regions with significantly mitigated segregation behavior. The spectral analysis of the local and global pressure transient data in the frequency domain revealed a pronounced difference between the two flow strategies. The application of the MDD inlet flow strategy eliminated the disturbances from the pulsed fluidized bed irrespective of the pulsation frequency.

Analysis of the Usability of Iron Ore Ultra-Fines for Hydrogen-Based Fluidized Bed Direct Reduction-A Review

This review focuses on the usability of iron ore ultra-fines for hydrogen-based direct reduction. Such technology is driven by the need to lower CO₂ emissions and energy consumption for the iron and steel industry. In addition, low operational and capital expenditures and a high oxide yield because of the direct use of ultra-fines can be highlighted. The classification of powders for a fluidized bed are reviewed. Fluid dynamics, such as minimum fluidization velocity, entrainment velocity and fluidized state diagrams are summarized and discussed regarding the processing of iron ore ultra-fines in a fluidized bed. The influence of the reduction process, especially the agglomeration phenomenon sticking, is evaluated. Thus, the sticking determining factors and the solutions to avoid sticking are reviewed and discussed. The essential theoretical considerations and process-relevant issues are provided for the usability of iron ore ultra-fines for hydrogen-based fluidized bed direct reduction.