USE OF DUPLEX STAINLESS STEEL IN AN AMMONIA-STRIPPING OF UREA PLANTS Russian patent published in 2018 - IPC B01D1/06 C07C273/04 B01D3/34 F28F19/00 B01J19/02 

FIELD: chemistry.

SUBSTANCE: invention relates to the creation or upgrading of ammonia stripping or self-stripping plants for the synthesis of urea. Ammonia stripping or self-stripping plant for the synthesis of urea, comprising a high-pressure synthesis loop that includes a synthesis reactor, a shell-and-tube stripper, and a condenser, said stripper comprising a shell and a bundle of tubes, and being arranged to provide the stripping of a carbamate solution fed to said tubes by means of heat, and optionally by means of ammonia as a stripping medium, wherein tubes of said stripper are made of a duplex stainless steel which is one of the following: A) Safurex^® steel, specifically 29Cr-6.5Ni-2Mo-N, which is also designated by American Society of Mechanical Engineers (ASME) Code 2295-3 and by Unified Numbering System (UNS) S32906, of B) DP28W™ steel, specifically 27Cr-7.6Ni-1 Mo-2.3W-N, which is also designated by ASME Code Case 2496-1 and by UNS S32808. Methods for upgrading a plant for synthesis of urea. Method for ammonia stripping or self-stripping for synthesis of urea.

EFFECT: technical result is an increase in the efficiency of the urea synthesis process due to the use of duplex stainless steel.

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