DESCRIPTION The FT80 Tall Form Spray Dryer and FT81 Tall Form Spray Chiller have been purpose designed to enable laboratory quantities of products to be processed. Despite the size of the equipment, thepowders produced will be comparable to large-scale production dryer capability. Both systems offer unparalleled flexibility with separate, individually controlled inlet and outlet fans, together with variable nozzle positions and selection of co- or counter-current flow configurations. This flexibility is enhanced by an unsurpassed range of options, purpose-designed for laboratory and research use. With the appropriate accessories it is possible to change from spray-drying to spray-chilling configurations in a matter of minutes, thus adding further unique experimental capability. CO-CURRENT SPRAY-DRYING CONFIGURATION The liquid to be dried is pumped to the top of the drying chamber by a variable-speed progressing cavity pump, which provides a very smooth flow and constant flow rate. It is atomised by a two-fluid nozzle and enters the drying chamber as a fine droplet dispersion. Hot air is blown into the chamber, on to the droplets causing flash evaporation of the surface moisture. The bound moisture in the particles is evaporated in the time that they fall to the discharge point at the base of the cone (the residence time). In this configuration the particle temperature will never exceed the wet bulb temperature of the exhaust air. A variable-speed centrifugal fan provides control over the inlet air flow and a steady inlet temperature is achieved by using a three-term controller in conjunction with an electric heater. A second variable speed fan draws air from the chamber through a cyclone separator. This ‘push-pull’ fan system provides flexibility to operate the chamber at variable pressures with variable residence times. Two powder collection points are provided, one at the bottom of the main chamber, and one on the cyclone separator. This enables particles of different sizes to be collected simultaneously and/or separately. Exhaust-air relative humidity can be measured and controlled so as to enable the system to run at the required RH level. The nozzle is an external-mix two-fluid atomising nozzle. Compressed air is directed onto the liquid stream as it leaves the nozzle body and immediately atomises it. With this type of nozzle the orifice is larger than a single fluid type, and so it is possible to atomise more viscous products and even products containing suspended solids. TECHNICAL SPECIFICATIONS GENERAL Liquid feed: 2-7 l/hr from variable-speed progressive cavity pump Air flow: Up to 30scfm, using variable-speed fans in ‘push-pull’ configuration Chamber residence times: Variable up to 9 seconds Powder collection points: Separate chamber and cyclone discharge points Atomisation nozzles: 2-fluid type SPRAY DRYING Electric air heater: 4.5kW Drying air temperature: 50-250˚C Evaporation rates: 1.5-3 l/hr Typical particle size range: 20-120 microns SPRAY CHILLING Air temperature: 2˚C minimum (Note: not all parameters are necessarily achievable simultaneously)
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