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1

Steps in urea synthesis?

Synthesis
Decomposition (with recovery)
Concentration
Granulation

The first step is urea synthesis where NH3 and CO2 are reacted to get urea according to the equation:

2NH_3+CO_2→NH_2 COONH_4
Which is fast and exothermic, there are also some undesirable side reactions.
There is then a decomposition reaction to help decompose the undesirable byproducts and to remove NH3 and CO2 which are recycled back into the reactor.
The urea is concentrated up by boiling off excess water.
Then it is cooled down and put through granulation which is similar to a mix of spray drying and crystallisation, where seed urea is used to ‘grow’ urea granules which are separated and removed from the reactor.

2

Steps in ammonia synthesis? (13)

- Desulfuriser
- Steam reformer
- Air reformer
- Waste heat boiler
- Shift converter
- CO2 removal
- Methanation
-Compression and cooling
- Mixer
- NH3 converter
- Cooled to 30
- Decompression
- Get ammonia