Abstract SYMPHOS 2011

By Eng. Luis María de Urquiola
Technical Manager
COMSPAIN
COOLING FERTILIZERS AND PHOSPHATES :
BY ROTARY DRUM OR FLUID BED ?
PH-O-10
OVER 30 years ago, fluidification – the use of the fluid bed – began to be adopted on a commercial scale by industry.
A COMSPAIN Rotary Drum for fertilizer, capacity 700 T/h of NPK/DAP
A fluid bed consists of two elements, one solid, in this instance fertilizer granules, and one gaseous (cooling air).
“Fluidification” is achieved by pumping cooling air through the solid particles. This agitates the solid particles,
producing a fluid bed in which the physical characteristics of the solid/gaseous mixture approximate those of a
liquid. The exchange of heat between the solid and gaseous elements of the fluid bed thus formed is a mechanism
employed in equipment which provides a competitive alternative to other product cooling options in fertilizer
industry applications, such as rotary drums.
From the point of view of thermal interchange, the fluid bed option has great advantages:
(I) there is close contact between the cooling air and the solid particles (fertilizer granules);
(II) the circulation granules are always separated from each other by the air, exposing all their free surfaces to
the cooling effects of the fluid bed and speeding up the product cooling process;
(III) the constant movement and rotation of the particles also ensures a more uniform cooling process;
(IV) absence of shocks/falling during the cooling process and very reduced residence times within the cooling
plant minimizes granule breakage;
(V) as a consequence of (IV), fewer fines are created during the fluid bed cooling process, making the process
of lines cleaning and dedusting prior to venting of exhaust air easier, reducing dust levels in the vented air.
The cooling of granular fertilizers after the completion of the granulation, drying and classification process is
essential. By reducing the temperature of the product to close to ambient, condensation and other problems
affecting product quality e.g. product degradation (breakage of the granules) and caking/compacting of bagged
product, can be eliminated.
COMSPAIN has over 22 years of experience in addressing such problems throughout the world by supplying
equipment for new or revamped plants. The fertilizer equipment produced by COMSPAIN includes rotary drums and
fluid beds; in addition, the company can provide advice to potential clients on their product cooling problems. In
the last two years alone, COMSPAIN has been involved in 23 fertilizer-related projects (in Colombia, Korea, Japan,
China, Spain, Tunisia, South Africa, France, Ireland, Germany, etc.); the projects have included the installation of a
turn-key granulation plant (in South Africa) and replacing a rotary drum with a fluid bed cooler (in China).
Using this wealth of experience, here COMPSPAIN’s Technical Manager Eng. Luis María de Urquiola discusses the
relative merits of the rotary drum and the fluid bed as cooling mechanisms for granular fertilizers.
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