Ammonia is the key intermediate product in the production of all nitrogen fertilizers. Urea is the main nitrogen fertilizer product; it has a high nitrogen content and its transport is relatively easy and cheap. Ammonia is usually upgraded on site to urea as urea production requires CO2 which is a by-product of the ammonia production.

One of the largest towers in an ammonia plant is the CO2 absorber and the respective CO2 regenerator, also called CO2 stripper. In the CO2 absorber column, the CO2 present in the synthesis gas is absorbed by a scrubbing liquid, also called absorbent (usually either an alkanol-amine or hot potassium carbonate). This CO2-rich absorbent is then sent to the regenerator column, where the CO2 is desorbed, and the lean solvent sent back to the absorption column. 

The energy consumption of the ammonia plant is heavily influenced by the efficiency of the CO2 removal process. In solvent based C02 scrubbing processes, hydraulic power recovery turbines (HPRT’s) are a highly efficient method of recovering energy which must otherwise be dissipated with a pressure breakdown valve.  Up to 85% of the energy can be recovered which reduces the utility demand on the lean amine pump.  Automatic clutch system engages and disengages the HPRT unit during start-up and shutdown or low pressure upset condition.

Efficient ammonia and urea production 

To promote the contact of the absorbent with the synthesis gas, usually random packing is used to fill the absorption towers. NeXRing, the newest generation of random packing from Sulzer Chemtech, allows to increase the capacity of such absorption towers up to 35%. Or, by choosing the appropriate type of NeXRing, it is possible to increase efficiency, i.e. to decrease the CO2 content in the off gas. New build columns can also profit form the advantages of the 4th generation NeXRing random packing. They can be planned smaller and slimmer, reducing CAPEX.

If the absorption column is equipped with trays and additional capacity requirements asks for a revamp, Sulzer Chemtech can support you in finding the appropriate tray type for replacement. Or advise for a replacement of the trays by random or structured packing for an even larger increase in capacity.

The CO2 absorption and desorption columns are not the only one which can profit of the advantages of the newest developments in random and structured packing. Also all the other columns, like saturators, direct coolers, flash drums, NH3 absorption columns, HP and LP flashers, NH3 distillation columns, condensate and ammonia strippers, etc. can be optimized to boost capacity and efficiency.

The MellaTech™ column internals are the ideal complement to the latest generation of random and structured packings – since a column without proper internals like the right liquid distributors, liquid collectors and gas distributors will not be able to deliver its full potential.

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