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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)