A GEA Niro FSD™ spray dryer combines spray drying and fluid bed drying into Fluidized Spray Drying. It produces coarse, agglomerated, free-flowing dustless powder of a quality so superior that is used as a benchmark worldwide.
The Fluidized Spray Dryer concept was developed by GEA Process Engineering (then Niro) around 1980 to improve energy efficiency and final product quality in spray drying without causing problems with deposits in the drying chamber. Since then the design has been developed continuously making it still a state-of-the-art spray dryer.
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Drying in more stages
A prerequisite for the Fluidized Spray Drying concept was spray drying in two stages. The GEA Niro FSD™, however, operates with three drying stages, each adapted to the moisture content prevailing during the spray drying process.
In the preliminary drying stage the concentrate is atomized by co-current nozzles placed in the hot drying air duct. The air enters the spray dryer vertically through the air disperser at high velocity, ensuring optimal mixing of the atomized droplets with the drying air. The evaporation takes place instantaneously during the passage vertically down through the drying chamber. In this first stage drying, the particles are not completely dried.
At high moisture content, the powder will exhibit high thermo plasticity and becomes very sticky, but the air flow in the FSD™ spray dryer is designed in a way, that prevents the particles from sticking to the drying chamber, but led directly into the integrated static fluid bed for the second-stage drying. If the carbohydrate and/or fat content of the powder is high, then cold air is used to pre-cool the product. The integrated static fluid bed is supplied with air at a sufficient velocity for fluidizing the product and temperature for the second stage drying. The drying air from the pre-liminary and second-stage drying leaves the chamber from the top.
When the powder has reached the right moisture content, it is discharged via a rotary valve into a GEA Niro VIBRO-FLUIDIZER™ for the final drying and subsequent cooling.
Drying/cooling air from the chamber and VIBRO-FLUIDIZER™ is passed through a cyclone or a CIP-able bag filter, separating the powder contained in the air. The fine powder is returned back to the atomization device, the chamber cone (fluid bed), or the VIBRO-FLUIDIZER™ depending on the requirements to the final powder bulk density.
The plant can be designed and delivered for a full manual and/or automatic CIP Cleaning In Place including CIP Kitchen with tanks, pumps, valves and instrumentation.
The high velocity air inlet for the primary drying creates a venturi effect, the vacuum of which will suck surrounding air - with entrained fines particles - into the wet atomizer cloud. This will result in a "spontaneous agglomeration" and a powder with a coarse structure. A continuous supply of dry fines particles from the cyclones or bagfilter can be applied. These fines will stick to the semi-dry particles enhancing the agglomeration.
Producing non-agglomerated powders, all fines from the cyclone or bag filter are returned to the VIBRO-FLUIDIZER™.
It is possible to operate the GEA Niro FSD™ spray dryer at a high primary drying air temperature (up to 220-275° C) for an extremely short residence time, and still maintaing a good solubility of the powder. The gives a very sound drying economy (10-15 % less compared to conventional two-stage drying) that - together with its relatively small dimensions - makes it a very attractive solution. To improve the drying economy further a heat recovery system can be installed.
Today the GEA Niro FSD™ spray dryer is the preferred spray dryer for top quality products like infant milk formula/baby foods, coffee whitener, Inulin, carbohydrates, yeast extract and maltodextrine, where powder structure, bulk density, particle size distribution and flowability is of importance together with “dust free” behavior when the powder is used.
The GEA Niro FSD™ Fluidized Spray Dryer forms the key element in a complete process line for food and dairy powders.
All plants designed and supplied by GEA Process Engineering will enable the end user to obtain approvals put forward by the EU directive.