The three patented technologies in the Nano Spray Dryer B-90 will enable production of small particles and reduce R&D costs due to small sample volumes and higher yields.
The drying gas enters laminarly from the top into the drying chamber and is heated up to the set inlet temperature The piezodriven spray nozzle generates ultra-fine droplets, which are gently dried to solid particles The dried solid particles are electrostatically charged and collected at the collecting electrode The drying gas exits the spray dryer, the outlet temperature is measured, in addition, the gas is filtered
The droplet generation is based on a piezoelectric driven actuator, vibrating a thin, perforated, stainless steel membrane (mesh) in a small spray cap The membrane features an array of precise micron-sized holes. The actuator is driven at an ultrasonic frequency, causing the membrane to vibrate, ejecting millions of precisely sized droplets every second with very narrow droplet size distribution
Compact porous metal foam for optimal heating energy input Short heat-up times up to 120 °C Generation of laminar gas flow in the drying section Connvective heat transfer between droplets and gas Fast heating control by pluggalbe PT-1000 temperature sensor
Particle separation rate is independent of particle mass (as in cyclones) and allows collection of fine nanoparticles (separation efficiency >99%) Excellent product yields up to 90 % for small sample quantities <100 mg Simple particle collection with manual particle scraper Integrated outlet gas filter for user and environment protection
With the Mini Spray Dryer B-290 or with the Nano Spray Dryer B-90 with the Inert Loop B-295 it is possible to spray with organic solvents without risk of explosion, because the system works under inert conditions.
The outlet temperature is depending on the parameters inlet temperature, sample feed rate, sample concentration and aspirator rate. A change in one of those parameters will either cause the outlet temperature increase or decrease.
The limiting factor is the peristaltic pump. So the sample still has to be pumpable. This will be possible with a viscosity up to 300 cps with the Mini Spray Dryer B-290 or 10 cps with the Nano Spray Dryer B-90.
Major differences: B-90 for smaller sample quantities (mL samples, mg powder amounts), higher yields up to 90% and smaller particle sizes (submicron) B-290 is the classical spray dryer for medium laboratory sample quantities at a wide range of applications (also viscous substances and fruit juices possible). Its scale-up is more straigthforward.
So far we didn’t see any negative effects. The particle charge is released after deposition on the collecting metal tube electrode. We have beta testers that sprayed proteins, which remained active after the spray drying process. We will study this question more detailed during the beta-test phase. First tests with model proteins revealed marginal effects on protein stability or activity.
The particles will receive electrostatic charges which will remain on the particle surface. The larger particles carry a higher charge and will gather in the upper half of the electrode. Smaller particles carry a lower charge and will accumulate in the lower half of the electrode. Therefore BUCHI developed an efficient particle size separator!