Use of duplex stainless steel in an ammonia-stripping of urea plants

摘要

In an ammonia stripping or self-stripping plant for the synthesis of urea, it is disclosed that a shell-and-tube stripper has a bundle of tubes made of a duplex stainless steel 29Cr-6.5Ni-2Mo-N according to UNS S32906 or 27Cr-7.6Ni-1Mo-2.3W-N according to UNS S32808. A revamping of urea plants is also disclosed, including the revamping of ammonia stripping plants, self-stripping plants and conventional total recycle plants, wherein said duplex stainless steel is used for the tubes of the stripper.