Numerical Study and Experimental Validation of Skim Milk Drying in a Process Intensified Counter Flow Spray Dryer

This research presents 3D steady‐state simulations of a skim milk spray drying process in a counter‐current configuration dryer. A two‐phase flow involving gas and discrete phase is modeled using the Eulerian–Lagrangian model with two‐way coupling between phases. The drying kinetics of skim milk is incorporated using the Reaction Engineering Approach. The model predictions are found to be in accordance with the experimental temperature measurements with a maximum average error of 5%. The validated computational model is employed further to study the effects of nozzle position, initial spray Sauter Mean Diameter (SMD), air inlet temperature, and feed rate on the temperature and moisture profiles, particle impact positions, drying histories, and product recovery at the outlet. The location of the nozzle upwards (≈23 cm) resulted in maximum product recovery and increased the mean particle residence time at the outlet. A similar trend was observed for the highest feed rate of 26 kg/h owing to the increased spray penetration upstream in the chamber. The maximum evaporation zone was detected close to the atomizer (0–10 cm) when the spray SMD is 38 μm, whereas it shifts upstream (40–50 cm) of the dryer for an SMD of 58 μm. The high air inlet temperature resulted in enhanced evaporation rates only in the initial 10–20 cm distance from the atomizer. The results obtained in this study are beneficial for the development of the novel vortex chamber‐based reactors with a counter flow mechanism

Experimental analysis of spray drying in a process intensified counter flow dryer

This research presents an experimental analysis of a counter flow spray drying process using water and skim milk as a feed. The study was performed by examining the droplet size distribution of sprays and the temperature profiles in the dryer. The influence of air inlet temperature, air mass flow rate, feed flow rate, and droplet size on air temperatures in the dryer was evaluated. The evaporation and deposition zones were found to be highly dependent on the droplet size. The obtained results show that it is possible to achieve efficient contact between hot air and spray in a small volume using a counter-current mechanism

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

[EN] 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.This research is conducted within RVO-Vortex chamber II Project-TEEI115007, in collaboration with ISPT (Drying and Dewatering cluster), Royal FrieslandCampina, Université Catholique de Louvain, Unilever and Energy Research Centre of the Netherlands (ECN). Authors would like to express their gratitude to RVO for the financial support and to all project members for the fruitful discussions during the meetings. Furthermore, authors would like to convey their special thanks to Prof. Juray De Wilde, Mr. Axel de Broqueville and Mr. Thomas Tourneur (Université Catholique de Louvain) for providing the geometry, operating conditions and experimental data.Jamil Ur Rahman, U.; Baiazitov, I.; Pozarlik, A.; Brem, G. (2018). CFD study of air flow patterns and droplet trajectories in a lab scale vortex chamber spray dryer. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 1349-1356. https://doi.org/10.4995/IDS2018.2018.7686OCS1349135

Numerical Study toward Optimization of Spray Drying in a Novel Radial Multizone Dryer

In this paper, an intensified spray-drying process in a novel Radial Multizone Dryer (RMD) is analyzed by means of CFD. A three-dimensional Eulerian–Lagrangian multiphase model is applied to investigate the effect of solids outlet location, relative hot/cold airflow ratio, and droplet size on heat and mass transfer characteristics, G-acceleration, residence time, and separation efficiency of the product. The results indicate that the temperature pattern in the dryer is dependent on the solids outlet location. A stable, symmetric spray behavior with maximum evaporation in the hot zone is observed when the solids outlet is placed at the periphery of the vortex chamber. The maximum product separation efficiency (85 wt %) is obtained by applying high G-acceleration (at relative hot/cold ratio of 0.75) and narrow droplet size distribution (45–70 μm). The separation of different sized particles with distinct drying times is also observed. Smaller particles (<32 μm) leave the reactor via the gas outlet, while the majority of big particles leave it via the solids outlet, thus depicting in situ particle separation. The results revealed the feasibility and benefits of a multizone drying operation and that the RMD can be an attractive solution for spray drying technology