Urea production plant

Patent metadata

Field	Value
Publication number	US-9732033-B2
Application number	US-201615246334-A
Country	US
Kind code	B2
Filing date	Aug 24, 2016
Priority date	May 3, 2012
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Disclosed is a plant for the production of urea. The plant comprises conventional sections for synthesis and recovery, for evaporation and condensation, for urea finishing, and for dust scrubbing. According to the invention, an additional evaporation and condensation loop is introduced from and to the dust scrubbing section. This loop results in a more favorable energy consumption of the plant.

First claim

The invention claimed is:

1. A process for the preparation of urea comprising:
(a) one or more synthesis and recovery steps wherein ammonia and carbon dioxide are reacted to form urea and wherein an aqueous solution comprising urea is formed;
(b) an evaporation step wherein water is evaporated from the aqueous solution formed in (a) so as to result in a first concentrated urea-comprising liquid and an first aqueous vapor phase;
(c) subjecting said first aqueous vapor phase of (b) to a first condensation step to give an aqueous solution;
(d) subjecting the first concentrated urea-comprising liquid of (a) to a finishing treatment resulting in solid urea, wherein heat is removed by means of a cooling gas;
(e) subjecting the cooling gas of (d) to dust scrubbing, wherein urea is recovered in an aqueous stream;
(f) subjecting said aqueous stream of (e) to evaporation so as to result in a second concentrated urea-comprising liquid and a second vapor phase, wherein the evaporation is conducted in an evaporation step separate from the evaporation step (b), and wherein the second concentrated urea-comprising liquid is recirculated and subjected to the finishing step (d), and
(g) subjecting the vapor phase originating from the separate evaporation step (f) to a second condensation step separate from the first condensation step (c), and
(h) using the condensate from said second condensation step (g) in the dust scrubbing step (e).

2. The process of claim 1 wherein the condensate from the second condensation step (g) is subjected to hydrolysis and steam stripping.

3. The process of claim 1 wherein the dust scrubbing of (e) employs circulating urea solution as washing agent and the condensate from the second condensation step (g) is subjected to hydrolysis and steam stripping.

4. The process of claim 3 wherein the aqueous stream of (e) contains 10-60% by weight of urea.

5. The process of claim 4 wherein the condensate from the second condensation step (g) is subjected to hydrolysis and steam stripping.

Assignees

• Stamicarbon

Inventors

• Mennen Johannes Henricus
• Meessen Jozef Hubert

Classifications

• C07C273/04 Primary

  from carbon dioxide and ammonia · CPC title

• B01D5/00 Primary

  Condensation of vapours; Recovering volatile solvents by condensation (B01D8/00 takes precedence; condensers F28B) · CPC title

• B01D47/00

  Separating dispersed particles from gases, air or vapours by liquid as separating agent (B01D45/10 takes precedence; fractionating columns or parts thereof B01D3/16) · CPC title

• Y10T29/49352

  Repairing, converting, servicing or salvaging · CPC title

• B01D5/006

  with evaporation or distillation · CPC title