초록

This invention pertains to the field of producing ammonia. More specifically, the present invention relates to reducing the costs of producing a unit amount of ammonia, particularly the energy costs, by the utilization of an enhanced boiling surface in the refrigeration zone of the process.

대표청구항 ▼

In a process for producing ammonia which comprises: (a) reacting a nitrogen-hydrogen ammonia synthesis gas stream in the presence of an ammonia synthesis catalyst at conditions effecting partial conversion to ammonia; and (b) cooling the reacted synthesis gas stream to a temperature below the dewpoi

In a process for producing ammonia which comprises: (a) reacting a nitrogen-hydrogen ammonia synthesis gas stream in the presence of an ammonia synthesis catalyst at conditions effecting partial conversion to ammonia; and (b) cooling the reacted synthesis gas stream to a temperature below the dewpoint of ammonia so as to condense said ammonia by indirect heat exchange with ammonia refrigerant in at least two or more stages of cooling wherein each successive stage cools the reacted synthesis gas to a lower temperature with the last stage of cooling providing the lowest reacted synthesis gas temperature T, said indirect heat exchange having an overall heat transfer coefficient Uo, and wherein the ammonia refrigerant is provided by a compressor having at least two or more stages of compression, each stage of compression requiring a corresponding respective amount of compression energy to compress the ammonia such that a total amount of energy E is expended for compression and each stage of compression having an inlet suction pressure and an outlet discharge pressure; the improvement which comprises decreasing the amount of compression energy expended per unit amount of ammonia produced in the process by: (i) providing heat exchange apparatus for cooling the reacted synthesis gas with ammonia refrigerant having a thermally conductive wall with an enhanced boiling surface on one side of said wall in at least the last stage of cooling such that the ammonia refrigerant is in contact with the said enhanced boiling surface during the indirect heat exchange; and (ii) increasing the suction pressure to at least the first stage of compression.