Slot rectangular spouted fluid bed dryers and granulators

What is Spouted Fluid Bed Drying/Granulation?


Unlike conventional shallow fluid bed dryers, spouted fluid bed dryers comprise a deep vessel filled with seed particulate through which super-heated steam(SHS) is passed vertically via a small opening (or slot) located at the base of the vessel.  This vessel could be either round or rectangular. 

How Does Spouted Fluid Bed Drying/Granulation Work?


At the correct operating conditions, the resulting high velocity SHS jet causes particles to rise rapidly within the centre core (dilute zone) of the bed of moving solids.

Particles exiting the upper surface of the bed rain back to the outer annular region between the rising dilute zone and the outer “dense zone” which forms a conduit to return the particles back to the bottom end of the vessel. 

When spraying a wet product feedstock (slurry) on this “spouted fluid bed”, spherical granules are created by “layer forming” depositing of feedstock solids onto the dry “seed” material rotating in a circular pattern inside the vertical vessel. These round granules, which could be “grown” to any desired diameter, are then continuously removed from the “spouted bed” as the final product.

Slot Rectangular SFB dryers / granulators


Green Circle, together with its associates, designs and builds “Slot Rectangular” family of Spouted Fluid Bed dryers and granulators to meet end user requirements.  These bespoke Slot Rectangular designs allow dryers or granulators to be scaled up to suit most any application.  

SFB Benefits 


  • Direct contact, low-pressure, super-heated steam (SHS) dryer


  • Low-oxygen drying for highly volatile slurries or pastes


  • Small footprint with no mechanical rotating components


  • Closed “working” loop system combined with exhaust gas scrubber


  • No back mixing required - Low TS (Total Solids) compatibility


  • Fully automated and insensitive to feedstock moisture


  • Granulated end product in various sizes


  • Requires less air than conventional fluid bed dryers

Typical SFB Drying Diagram



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