Sonication in a urea or melamine synthesis process

Patent metadata

Field	Value
Publication number	US-2018071708-A1
Application number	US-201615563460-A
Country	US
Kind code	A1
Filing date	Mar 11, 2016
Priority date	Mar 30, 2015
Publication date	Mar 15, 2018
Grant date	—

Abstract

Process and respective reactor for urea or melamine synthesis, comprising sonication treatment of at least part of a reaction liquid mass or two-phase mixture contained inside said reactor.

First claim

1 . A process for the synthesis of urea from ammonia and carbon dioxide, or for the synthesis of melamine from urea, inside a chemical reactor, said process comprises comprising a sonication treatment of at least part of a reaction liquid mass or two-phase mixture contained inside said chemical reactor.

2 . The process according to claim 1 , wherein said sound waves have a frequency in the range 1 kHz to 1 MHz.

3 . The process according to claim 2 , wherein said sound waves have a frequency equal to or greater than 20 kHz.

4 . The process according to claim 1 , said sound waves being generated by one or more electrical or mechanical sources.

5 . The process according to claim 1 , wherein the sonication treatment is performed in a sonication zone inside said chemical reactor.

6 . The process according to claim 5 , comprising the circulation of a liquid phase or liquid/vapour phase through at least one reaction zone and a recirculation zone, which are arranged coaxial and concentric inside said reactor, wherein the sonication treatment is performed in at least one of said two reaction and recirculation zones.

7 . The process according to claim 6 , for melamine synthesis, wherein the reaction zone is a primary reaction zone fed with urea melt.

8 . A reactor for urea synthesis or melamine synthesis according to the process of claim 1 , wherein it comprises at least one sonication sound waves source.

9 . The reactor according to claim 8 , wherein said sound waves source is located inside a sonication chamber.

10 . The reactor according to claim 9 , said sonication chamber being delimited, inside the reactor, by a cylindrical wall or by a vertical-axis tube.

11 . The reactor according to claim 10 , said chamber being coaxial with the reactor.

12 . The reactor according to claim 8 , wherein said source is designed to produce sound waves with a frequency in the range of 1 kHz to 1 MHz.

13 . The reactor according to claim 8 , comprising a reaction chamber and a recirculation chamber which are concentric and coaxial, wherein said at least one sound waves source is located inside one of said chambers.

14 . The reactor according to claim 13 , the reactor being intended for melamine synthesis, wherein the reaction chamber is delimited by a central tube and is directly in communication with an inlet for urea melt, and the recirculation chamber is an annular chamber around said reaction chamber and comprises heating elements.

15 . The reactor according to claim 8 , wherein it comprises a mechanical stirrer arranged so as to direct a liquid phase, contained inside the reactor, towards said sonication source.

16 . Use of a sonication treatment inside a reactor for urea synthesis or inside a reactor for melamine synthesis, wherein said treatment provides transmission of sound waves to at least part of a liquid mass or two-phase mixture contained inside said reactor.

17 . The process according to claim 3 , wherein said sound waves have a frequency of 20 to 40 kHz.

18 . The reactor according to claim 12 , wherein said source is designed to produce sound waves with an ultrasound frequency of at least 20 kHz.

Assignees

• Casale Sa

Inventors

• Rizzi Enrico

Classifications

• C07C273/12

  combined with the synthesis of melamine · CPC title

• C07C273/04 Primary

  from carbon dioxide and ammonia · CPC title

• B01J19/246

  internally, i.e. the mixture circulating inside the vessel such that the upward stream is separated physically from the downward stream(s) · CPC title

• Y02P20/582

  Recycling of unreacted starting or intermediate materials · CPC title

• B01J19/10 Primary

  employing sonic or ultrasonic vibrations · CPC title