Method for revamping a self-stripping urea plant

Patent metadata

Field	Value
Publication number	US-9770699-B2
Application number	US-201414778460-A
Country	US
Kind code	B2
Filing date	Mar 5, 2014
Priority date	Mar 27, 2013
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

A method for revamping a self-stripping urea plant comprising the installation of a new CO2-stripping synthesis section ( 6 ), wherein at least part of the aqueous urea solution ( 10 ) leaving said new section ( 6 ) is directed to the existing low pressure recovery section ( 4 ) of the self-stripping plant, by-passing the existing self-stripping high-pressure section ( 2 ) and medium pressure treatment section ( 3 ).

First claim

The invention claimed is:

1. A method for revamping a self-stripping urea plant, said plant comprising: a high pressure urea synthesis section including at least a reactor, a thermal stripper or an ammonia stripper and a condenser; a medium pressure treatment section; a low pressure recovery section, the method comprising the following steps:
installation of a CO 2 -stripping synthesis section, where ammonia and carbon dioxide are converted to an aqueous urea solution according to CO 2 -stripping process,
wherein said new CO 2 -stripping section comprises at least: a synthesis reactor, a stripper, and a condenser, which are part of a high-pressure loop, and
wherein at least a portion of the aqueous urea solution leaving said new CO 2 -stripping section is directed to said existing low pressure recovery section, by-passing the existing self-stripping high-pressure section and medium pressure treatment section.

2. The method according to claim 1 , wherein said new CO 2 -stripping section further comprises a scrubber.

3. The method according to claim 1 , said high-pressure loop operating substantially at the same pressure as the existing self-stripping synthesis section.

4. The method according to claim 1 , wherein a first portion of the aqueous urea solution leaving said new CO 2 -stripping section is directed to said low pressure recovery section, while a second remaining portion of said solution is directed to said medium pressure treatment section.

5. The method according to claim 4 , said first portion of urea solution being greater than said second portion.

6. The method according to claim 1 , wherein a portion of liquid ammonia and/or a portion of carbamate solution, which are recovered from the existing medium-pressure section, is fed to the new CO 2 -stripping section.

7. The method according to claim 6 , wherein said portion of liquid ammonia and/or portion of carbamate is fed to said CO 2 -stripping section via existing pumps of the self-stripping plants.

8. The method according to claim 1 , wherein: the existing self-stripping urea plant comprises more than one urea production lines in parallel, the aqueous urea solution leaving said new CO 2 -stripping section and by-passing the medium-pressure sections is split into a plurality of streams, and each of said streams is directed to a respective low-pressure recovery section of the existing urea production lines.

9. The method according to claim 8 , wherein some of the urea solution from the new CO 2 stripping section is also directed to one or more of the medium-pressure sections.

10. The method according to claim 8 , wherein respective portions of liquid ammonia and/or carbamate solution, recovered from the medium-pressure sections of the urea production lines, are directed to the new CO 2 stripping section.

Assignees

• Casale Sa

Inventors

• Scotto Andrea
• Bertini Paolo
• Gabbiadini Serena

Classifications

• B01J2219/00024

  Revamping, retrofitting or modernisation of existing plants · CPC title

• C07C273/04 Primary

  from carbon dioxide and ammonia · CPC title

• B01J10/00 Primary

  Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor (B01J19/08 takes precedence; separation, e.g. distillation, also combined with chemical reactions B01D, {e.g. B01D3/009}) · CPC title