Novel nozzle design for energy efficient spray drying of high viscous food liquids: Investigations on atomization performance and powder characteristics

Spray drying is a widely used process for the production of powder products. In this process, atomization is used to create fine droplets of feed liquids which are dried to particles in a heating gas stream. However, drying processes are known to be the most energy consuming processes used in food industry. A good way to reduce the overall energy consumption of spray drying processes is the use of alternative concentration methods before the actual drying step. But, with rising dry matter contents, the liquid viscosities of the used concentrates increase rapidly. This fact complicates the before mentioned drop formation step for all known atomization principles. Generally, pneumatic twin fluid nozzles are suitable for atomization of high viscous feed liquids. However, these atomizers are not used in an industrial scale, due to high gas consumption rates.
A possible solution for this current limitations could be the use of alternative gas injections in internal mixing pneumatic atomisers (IMPA). In our recent investigations, the influence of different dry matter to viscosity ratios on the resulting spray droplet size distributions were examined by using laser diffraction measurements. ... mehrAll experiments have been conducted with two different IMPA designs at varying gas-to-liquid ratios (GLR). The experiments show the possibility of creating sufficiently small mean droplet sizes at high viscosities and low GLRs for a subsequent drying step. In further experiments, these correlations are verified using a pilot scale spray dryer. The produced powders will be analyzed regarding particle size distribution, moisture content, water activity and instant properties.