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 MINORTM small quantities of solutions, suspension and emulsions can be dried into powder samples for further evaluation. MOBILE MINORTM 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.