CFD study of air flow patterns and droplet trajectories in a lab scale vortex chamber spray dryer

Abstract

In order to develop an alternative spray drying technology, a high drying rate in a smaller volume must be achieved. In this paper, results of CFD study are presented, carried out to investigate the possibility of spray drying in a novel design vortex chamber. The model is validated against experimental data, that makes a good agreement with an average error of 7% with only air and 24% with water spray. Results of temperature fields and droplet impact positions are discussed. The computations demonstrate that vortex chamber spray dryer can be an attractive solution for drying technology. Keywords: CFD; spray drying; vortex chamber; atomization;

Towards a multizone vortex dryer for dairy sprays

“…During the tests without water spray, the asymmetry is not so pronounced, suggesting that this is a consequence of the interaction between the counter flow hot air and feed spray. For the same mean droplet size, increasing the air inlet temperature should give faster evaporation rates due to the bigger temperature difference between the air and droplets [44]. The influence of the lower air inlet temperature on the evaporation rate is evident via Fig.…”

“…In conclusion, the predicted numerical results correspond sufficiently well with temperature measurements. A detailed discussion regarding the validation results is given in our former paper [44]. This section presents numerical investigations for optimizing the two-step spray drying process in a vortex chamber spray dryer.…”

“…This study investigates a novel compact dryer for producing skim milk powder (heat-sensitive material) based on a counter-current mechanism. The concept of the design originates from the Radial Multizone Dryer (RMD) [44][45][46], wherein a process intensified spray drying is achieved by applying high air inlet temperatures (300-400 °C) and high-G acceleration using vortex chamber technology. Recently, Rahman et al [65] studied numerically the benefits of RMD and identified optimum parameters (solids outlet location, droplet size, G-acceleration) for efficient spray drying operation in RMD.…”

“…The advent of multi-stage spray dryers (two or three stages) with integrated fluidized beds has improved the energy efficiency of the process by 13% [13][14][15][16][17]. Nevertheless, the drying systems are still far from beingThe evolution of a vortex chamber technology is a Radial Multizone Dryer (RMD) [44][45][46][47], shown in Figure 1.1-b. In this configuration, hot air enters axially into the central zone while the vortex is created via relatively cold airflow entering the RMD via the tangential channels; see Figure 1.1a.…”

“…The evolution of a vortex chamber technology is a Radial Multizone Dryer (RMD) [44][45][46][47], shown in Figure 1.1-b. In this configuration, hot air enters axially into the central zone while the vortex is created via relatively cold airflow entering the RMD via the tangential channels; see Figure 1.1a.…”