Ammonia process technology

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Ammonia process technology

Post by limane » Wed May 08, 2019 8:13 am

Hi, I would like to know what is the best market technology for ammonia production, between the diferente processes available, Haldor Topssoe, Uhde, KBR. And what is most eficiente in terms of enegy balance?

Thanks for your advice.

Luis Almeida

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Joined: Thu Apr 06, 2017 10:52 am

Re: Ammonia process technology

Post by gschulz » Fri Oct 04, 2019 6:41 pm

All the technology licensors you mention are in the top quartile of efficiency and installed capacity. Standard technology dates back to the green revolution (1970). By standard I mean primary reforming furnace, with secondary (air) reforming,etc.

After that appeared the technologies that enrich air with oxygen at secondary reforming, thus shifting reforming from primary to secondary reforming. This means less heat losses from furnace stack.

Also some more advanced technologies use cryogenic purification of synhtesis gas make up. this means you can have the same capacity with less catalyst (and reactor volume) , and operate at reduced pressure (lower capex). Operating at lower pressure in synthesis loop means at some point more difficulty to condensate ammonia, thus a bigger refrigeration compressor will be needed. But you save capex because purge is no longer needed at synthesis loop, thus no need for ammonia recovery washing column and hydrogen membranes.

The latest and more advanced concepts completely separate O2 from air, and use pure O2 at autothermal reformers. This means that you no longer walk the nitrogen through the front end, but instead you feed it right before entering the synthesis loop, either with a criogenic ¨coldbox ( KBR)¨ or a nitrogen wash column (Syncor). Thus capex is lowered especially at lower pressure sections with big equipment like CO2 removal (aMDEa,etc).

With autothermal reforming you can eventually get rid completely of the primary refomer furnace, whic is one of the most frequetly failed units due to operational mishaps (overfiring, tube ruptures). But it also allows increasing the operating presssure of the front end, because of the existing limitations of alloys for radiant tubes of primary reformer. The higher the reforming pressure, lower will the capex be.

Syncor Ammonia (Topsoe), is currently the newest concept, which will have its first operational unit soon at Perdaman Australia plant. However Syncor hubs are already proven for methanol production.

Choosing the optimal technology is always subject to the constrainst of the specific site. All the technolgy licensors will be able to achieve your required capacity, and they will optimize energy efficiency to numbers that will be very similar. But a PFD with a M&E balance is just a ¨fix¨picture, at a given gas composition and ambient temperature. You will have to figure out how all these options will operate under deviations from these ideal situation, given your site constraints.

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