The focal point of an ammonia plant is the synthesis loop, with the ammonia converter at its core.The ammonia converter vessel contains a cartridge for catalyst beds, heat exchangers and gas distribution pathways.Its internal design is very complex and is influenced by requirements such as assembling the internals inside the pressure vessel, inspection requirements, loading and unloading the catalyst.High per-pass conversion means lower circulation and lower operating pressure.Both factors have a positive effect on the energy efficiency of the plant, because consumption of both the synthesis gas compressor and the circulator will be lower.As technology and materials have improved, it has become possible to make fuller and more efficient use of the converter volume.Consequently, revamping the synthesis converter of an existing plant to the newest technology can be of huge benefit on account of its positive effect on overall plant efficiency.In recent decades, various licensors have provided technology for the ammonia synthesis loop, each with distinctive features: operating pressure, catalyst temperature control, heat removal, levels of inerts and loop layout.These differences are reflected in the design of the ammonia converter, in respect of not only the internals but also the pressure shell1.
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