Impurity esp. ammonia sepn. from synthesis purge gas contg. hydrogen - by two stage partial condensation with thermodynamic coupling through common heat exchanger to increase efficiency, prod. purity and economy

摘要

Sepn. of gaseous components (I) from synthesis purge gas (II) contg. H2, esp. of NH3 from (II) in NH3 synthesis, which interfere with the recovery of valuable materials (III), e.g., H2, comprises partial condensation at a temp. near the triple point temp.. The novelty is that both recovery of (III) in stage (1) and sepn. of (I) in stage (2) are carried out by partial condensation, with thermodynamic coupling of the 2 stages through a common heat exchanger, so that the excess cold from stage (1) is used in stage (2). Vaporisation of (I) after partial condensation is carried out in vacuo. The pressure difference between the (II) pressure at the outlet from synthesis and the pressure in the partial condensation of (I) is used for compressing the prod. expansion gas to the partial condensation pressure. A plate heat exchanger is pref. used. ADVANTAGE - Coupling the 2 stages increases the deg. of H2 recovery and (I) purity and also reduces operating costs.