Casale, axial-radial flow converter

An axial-radial flow converter has been introduced by Ammonia Casale [490,492, 551-553]. The special feature of this design is that gas can enter each catalyst bed both from the top (in axial direction) and from the side through perforations (in radial direction), see Fig. 6.11 (from [492]). The gas leaves the catalyst bed through perforations in the inner wall. There are no perforations in an upper part of the inner wall, and the gas entering at the top of the bed is therefore forced to flow through part of the catalyst in partially axial flow before it can leave the catalyst bed. This flow principle can be used in quench cooled... 

Fig. 6.11. Principle of axial-radial flow converter. Ammonia Casale design (from [492])...

Ammonia Casale Axial-radial flow through three catalyst beds with inter-bed heat exchange or quench cooling. A second converter holding the third bed has been used. 

Axial-radial flow pattern was introduced by Ammonia Casale. Converters with strictly radial gas flow require mechanical sealing of the top of each catalyst bed... 

Casale [905]-[910] has also successfully commercialized converters based on the axial - radial flow concept with indirect cooling. 

As mentioned above, Haldor Topsoe A/S, KBR, and Uhde GmbH share the major part of the market for new ammonia synthesis technology. For plant retrofits also others are active and especially for ammonia converter revamps, Ammonia Casale offer their ammonia synthesis technology. The main feature of the Casale technology is the so-called axial-radial flow synthesis converter (55, 56), and (57). 

As far as ammonia converter design is concerned. Ammonia Casale s technology has already been introduced in Section 7.2.3. Ammonia Casale converter designs using the axial-radial flow concept have achieved considerable success in recent years, particularly for modification of existing axial-flow converters. These converter retrofits can be achieved by in situ changes to the converter internals in the case of converters where the catalyst basket cannot be removed from the pressure shell. 

---