A new corrected formula to predict mean residence time of flexible filamentous particles in rotary dryers

Abstract

The mean residence time of granular particles is one of the most crucial indexes in drying processes. In this paper, a new formula for correction of the mean residence time (MRT) is proposed, which includes the correlation among the MRT and the slope, number of flights and moisture content of particle. As a consequence, the results obtained by the new corrected formula agree well with the experimental. Then, a series of experiments is presented to describe the mean residence time and motion performance of flexible filamentous granular particles under different operating conditions. In order to meet the requirements of description properly on the residence time of granular particles, slope and rotational speed of drum, moisture content of particle at the inlet, mass flow rate of particles, and velocity of air flow are taken into account. Experimental results on flexible filamentous particles demonstrate that the mean residence time is significantly influenced by those parameters mentioned above. Moreover, the decrease of drum slope makes the mean residence time rise, and the increase of rotational speed results in the dropping of mean residence time. The reduction of mean residence time becomes slower with the faster increase of rotational speed. Moreover, the mean residence time climbs following the increase of moisture content and mass flow rate of particles at the inlet while experiences a slightly drop with the increase of air flow velocity.