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Tiranga

       
           

               ADVANTAGE OF THE RADIAL FLOW OVER AXIAL FLOW

Because of the axial flow through the catalyst beds of conventional type 
convertors, the higher production capacities and the lower loop pressure 
resulting from the use of the centrifugal compressors have required 
increase in the diameter of the ammonia synthesis converter to keep the 
converter pressure drop at a reasonable level. Since the diameter of the 
pressure shell closure that can be manufactured is limited ,it becomes 
necessary to make the opening smaller than the shell diameter. With this 
design the basket can�t be removed unless the shell is cut. To avoid this, 
TOPSOE has adopted the radial flow principle to ammonia plant design.


The radial flow gives advantage both with respect to the process and to the 
mechanical design of the converter. The main mechanical advantage is the 
relatively small pressure shell diameter (relative to the capacity of the 
unit) which permits the use of  a full diameter closure, which has the 
advantage of giving easy access to the internals, thus facilitating the 
operations of loading and unloading catalyst and also inspection of the 
internals.


A further mechanical advantage is the simplicity of the catalyst beds. A 
conventional TVA type internals assembly designed for an operating pressure 
of about  4000 Psig was found to weigh about 25% more than a radial 
converter designed for the same operating conditions.

A process advantage is the very low catalyst pressure drop. In addition to 
the direct saving power consumption , this makes it possible to use 
catalyst having a particle size smaller than normal and consequently a 
higher catalyst activity.