Reactor for two-phase reactions, in particular for urea synthesis at high pressure and temperature

• US 6,120,740 A
• Filed: 01/05/1999
• Issued: 09/19/2000
• Est. Priority Date: 05/11/1994
• Status: Expired due to Term

• Current Assignee: Urea Casale SA (Casale Holding SA)
• Original Assignee: Urea Casale SA (Casale Holding SA)
• Inventors: Zardi, Federico, Silva, Paolo
• Primary Examiner(s): TRAN, HIEN THI
• Application Number:
  US09/226,909
• Time in Patent Office: 623 Days
• Field of Search: 422/193, 422/188-191, 564/73, 564/67, 202/158, 159/47.2, 261/114.3
• US Class Current: 422/644
• CPC Class Codes: B01D 3/22 with horizontal sieve plates or grids; Construction of sieve plates or grids
• CPC Class Codes: B01J 10/002 carried out in foam, aerosol or bubbles
• CPC Class Codes: B01J 19/006 Baffles
• CPC Class Codes: B01J 2219/00024 Revamping, retrofitting or modernisation of existing plants
• CPC Class Codes: B01J 2219/00777 horizontal
• CPC Class Codes: B01J 2219/185 vertical
• CPC Class Codes: B01J 2219/1943 cylindrical
• CPC Class Codes: B01J 3/04 Pressure vessels, e.g. autoclaves
• CPC Class Codes: C07C 273/04 from carbon dioxide and ammonia
• CPC Class Codes: Y02P 20/141 Feedstock
• CPC Class Codes: Y02P 20/582 Recycling of unreacted starting or intermediate materials

Abstract

A reactor for two-phase reaction, in particular for urea synthesis at high pressure and temperature of the type wherein a co-current flow of a gaseous phase and a liquid phase takes place, comprises a substantially cylindrical vertical external shell (2) in which is supported a plurality of superimposed horizontal perforated plates (6a-6e) in mutually spaced relationship and at least one opening (12a-12e) for liquid flow being defined in correspondence of each of the perforated plates. Advantageously the openings (12a-12e) for liquid flow are mutually offset so as to obtain a substantially zigzag preferential flow path for the liquid phase in the reactor.

Claims

1. A method for in-situ modernization of a reactor for urea synthesis at high pressure and temperature wherein a co-current flow of a gaseous phase and a liquid phase takes place in a vertical, tubular shell of the reactor in which is supported a plurality of superimposed horizontal perforated plates having a plurality of perforations in mutually spaced relationship, the method comprising the steps of replacing at least two adjacent existing perforated plates with corresponding perforated plates having respective mutually offset openings for liquid flow which are larger than said perforations for gas flow, each of said plates disposed in close proximity to said shell to provide a small peripheral gap to provide passivation against corrosion between said plate and said shell and having a downwardly depending collar extending around a perimeter of said plate.