Study of the Effect of Additional Fluidizing Agent Inlets on the Hydrodynamic Parameters of a Spouted Bed

Abstract

Relevance: drying of high-moisture dispersed materials, especially those prone to agglomeration and the formation of unstable lumps, is one of the most complex heat- and mass-transfer processes. Additional difficulties arise in the processing of polydisperse fiber-forming polymers, which are characterized by deterioration of fluidization conditions and instability of the hydrodynamic regime. In this regard, the search for design solutions that ensure increased particle mixing intensity and an expanded stable operating range of the spouted bed apparatus is of considerable interest.

Aim: this study investigated the effect of additional supply of the heat carrier to the peripheral zones of the apparatus on the motion of the solid phase and the main hydrodynamic parameters of the process.

Methods: experimental studies were carried out on a spouted bed unit with combined air supply through the lower and side inlets. To assess the mixing structure, an impulse tracer method was used, and the obtained response curves were processed using the method of moments. In addition, spouting curves were analyzed, the operating and limiting pressure drops were determined, the conditions for the onset of stable spouting were established, and the spouting number was calculated for different gas flow distribution modes.

Results: it was shown that redistribution of the heat carrier flow in favor of the side inlets leads to a significant intensification of the bed hydrodynamics. In this case, the transition velocity to the spouting regime and the maximum pressure drop decrease, while an increase in the spouting number indicates enhanced circulation exchange of particles within the apparatus. It was established that activation of peripheral flows improves the efficiency of heat carrier utilization, reduces the material processing time, and at the same time maintains the operating pressure drop at an acceptable level. Rational conditions for air flow distribution were determined, providing the most stable operating regime of the unit.

Conclusion: the obtained results confirm that the use of spouted bed apparatuses with additional peripheral supply of the heat carrier is a promising direction for drying high-moisture, lump-forming, and polydisperse materials that require intensified hydrodynamic action.