Suitable for existing plant.
H2 recovery from Purge.
Energy saving 0.04÷0.10 Gcal/MTNH3.
The HP-HRU is a cryogenic system developed and patented by Casale to recover pure reactants from the ammonia synloop purge stream. The process is made up of the following steps:
- The purge gas is treated to remove the ammonia it contains (water absorption)
- Dried using molecular sieves
- Treated in the Cold Box, wherein it is cooled and partially condensed. H2+N2 vapors are recovered mostly at loop pressure. The liquid Ar+CH4 are rejected as fuel after depressurization
The HP-HRU is preferably connected in parallel with the loop cold exchangers, or in parallel to the recycle compressor stage.
The main advantages achievable thanks to the Casale HP-HRU are:
- Hydrogen and nitrogen recovered at high pressure (up to 150 bar)
- Enhanced hydrogen and nitrogen recovery
- Enhanced inert removal
These advantages can be translated into two major revamping benefits for revamping and new plants:
- Higher H2 and N2 conversion
- Energy saving (typically 0.04÷0.1 Gcal/MTNH3)