Method for the separation of ammonia and carbon dioxide from aqueous solutions

Patent metadata

Field	Value
Publication number	US-9669360-B2
Application number	US-201514960662-A
Country	US
Kind code	B2
Filing date	Dec 7, 2015
Priority date	Sep 9, 2009
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

The present invention relates to a method for contemporaneously recovering ammonia and carbon dioxide from an aqueous solution thereof, possibly comprising their condensates, in a synthesis process of urea, characterized in that it comprises a hydrophobic microporous membrane distillation phase of an aqueous solution comprising ammonia, carbon dioxide and their saline compounds or condensates, said distillation being carried out at a temperature ranging from 50 to 250° C. and a pressure ranging from 50 KPa to 20 MPa absolute, with the formation of a residual aqueous solution, possibly comprising urea, and a gaseous permeate stream, comprising ammonia, carbon dioxide and water. The present invention also relates to an apparatus for effecting the above method and a production process of urea which comprises the above method.

First claim

The invention claimed is:

1. An equipment, comprising:
a distillation unit comprising a hydrophobic microporous membrane configured to operate at a temperature of 50 to 250° C. and at a pressure of 50 KPa to 20 MPa absolute;
a feeding line connecting the distillation unit to a urea synthesis reactor; and
a heating unit,
wherein
the feeding line feeds to the distillation unit an aqueous solution, which is a reaction effluent from the urea synthesis reactor comprising from 20 to 70% by weight of ammonia, from 10 to 60% by weight of carbon dioxide, from 10 to 70% by weight of water, and optionally urea;
the distillation unit distils the aqueous solution and forms a residual aqueous solution and a permeated gaseous stream comprising ammonia carbon dioxide, and water;
the hydrophobic microporous membrane contemporaneously recovers ammonia and carbon dioxide from the aqueous solution; and
the heating units heats the aqueous solution.

2. The equipment of claim 1 , wherein the heating unit comprises a microwave-generating device.

3. The equipment of claim 2 , wherein the microwave-generating device is arranged so as to irradiate the aqueous solution in such a way that a temperature of the aqueous solution increases along a direction of a stream of the aqueous solution.

4. The equipment of claim 1 , wherein the distillation unit comprises two or more sections which operate under different temperature and pressure conditions.

5. The equipment of claim 1 , wherein the aqueous solution comprises urea in a content of more than 0% and equal to or less than 60% by weight.

6. The equipment of claim 1 , wherein the hydrophobic microporous membrane comprises a hydrophobic polymer which forms a contact angle equal to or higher than 90 degrees with the aqueous solution.

7. The equipment of claim 1 , wherein the hydrophobic microporous membrane comprises a hydrophobic polymer which forms a contact angle equal to or higher 120 degrees with the aqueous solution.

Assignees

• Saipem Spa
• Saipem Spa

Inventors

• Casara Paolo
• Gianazza Alessandro

Classifications

• C02F1/44

  by dialysis, osmosis or reverse osmosis {(general membrane separation processes B01D61/00, membrane modules B01D63/00, electrodialysis C02F1/4693, combination of membrane modules and bioreactors C02F3/1268)} · CPC title

• C02F2101/16

  Nitrogen compounds, e.g. ammonia · CPC title

• C02F2103/36

  from the manufacture of organic compounds · CPC title

• C02F1/447

  by membrane distillation (distillation and evaporation without the use of membranes C02F1/04) · CPC title

• C07C273/04

  from carbon dioxide and ammonia · CPC title