Application: Small-scale evaluation of spray drying feasibility and testing of the unit for clients interested in a small spray dryer for their R&D applications.
Capacity: The evaporative capacity is 1-4 kg/h depending on the solvent and the minimum feed requirement is about 2 kg and not less than 200 g of solids.
Specification: The chamber has a 0.8 m diameter, a 0.6 m cylindrical height and a 60 degree conical bottom. The 80 kg/h of drying air is heated electrically and has a maximum inlet temperature of 300 °C. A chamber height extension piece is available to increase the height of the drying chamber with 23 cm.
Feed is supplied by a peristaltic or a mono pump and can be atomized by a rotary atomizer (type M-02) with a pneumatic drive or by a co-current or counter-current two-fluid nozzle. Product can be recovered from the chamber, cyclone and/or bag filter.
In the MOBILE MINOR™ small quantities of solutions, suspension and emulsions can be dried into powder samples for further evaluation. MOBILE MINOR™ test results provide important information for selecting the design and technical specification of a given drying project.
Types of atomization
Rotary atomizer
Located in the centre of the chamber roof. An air turbine drive operating from a 6 bar compressed air source supplies power to the atomizer wheel. A vaned atomizer wheel is used for non-abrasive feeds and an atomizer wheel with carbide bushings for atomizing abrasive feeds. Particles in the range 5-25 µm are created.
Two-fluid nozzle, co-current mode
Located also in the centre of the chamber roof. The atomization is created by compressed air at a pressure of 0.5-2.0 bar. The feed and atomizing gas are passed separately to the nozzle head where the atomization takes places. Two-fluid nozzles have the advantage of handling more viscous feeds. The co-current mode is selected for drying heat sensitive products to fine particles in the range 5-25 µm.
Two-fluid nozzle, fountain mode
Located in the cone of the drying chamber spraying upwards. The fountain mode is selected to meet a more coarse and free-flowing powder specification. Often used for fine ceramics and other non-heat-sensitive products. The counter-current flow offers a dryer performance with excellent heat utilization and provides the longer powder residence time in the drying chamber required to complete the drying to larger particles in the range 15-80 µm.