GEA Process Engineering (India) Private Limited
offers Column Dryers based on Barr-Rosin technology. The
Column Dryer is well suited to process Polymers, Organic Chemicals, and
Inorganics. However the feed to the Column Dryer must be non-sticky and in the
form of free-flowing crumbs, granules, beads, pellets, or powder.
The Column Dryer is an economical way to provide heat and long
residence time for slow diffusion-controlled drying. More often it is employed
as a second stage dryer, following a first stage rotary, fluid bed, or indirect
contact dryer. 
The Column Dryer is a
vertical vessel having a square cross sectional area with rounded corners. A
feed distributor is located below the feed inlet nozzle at the top of the
column. Similarly, a sweep gas distributor is employed at the bottom of the
column, above a vibrating discharge device. Internal heating elements
containing heat transfer fluid (steam, hot water, hot oil) are located in the
upper section of the column. Vertical baffles are installed in the vessel below
the heating plates and above the sweep gas distributor.
Free-flowing
solids are metered into the top of the column dryer and move downward by
gravity as a bed of solids in plug flow. As the solids pass the internal
heating elements, conductive heat transfer increases the product temperature.
Since the diffusion rate normally doubles for every 10°C rise in product
temperature, it is advantageous to heat up the solids prior to diffusion
drying. By employing a conductive heat transfer mechanism, the quantity of
stripping gas is minimized - - - now determined not by heating requirements but
by partial pressure, differential driving force and gas/solids contact
effectiveness. Once the feed solids have been preheated, the lower baffled
section of the column dryer provides sufficient residence time and contact with
the stripping gas for diffusion rate-controlled drying to occur.