# US 8,541,619 B2 · Method for purifying flue gases from combustion plants and then producing urea

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- Number: US 8,541,619 B2
- Document ID: US8541619B2
- Status: Granted
- Kind: B2
- Application number: 13/229,051
- Filed: 2011-09-09
- Published: 2012-03-15
- Granted: 2013-09-24
- Earliest claimed: 2007-05-02
- Assignees: Steag Energy Services GmbH
- Applicants: Hermann Winkler
- Inventors: Hermann Winkler
- Web page: https://patentgrep.com/patent/US8541619B2

## CPC

- B01D 53/62: Carbon oxides
- B01D 53/73: After-treatment of removed components
- B01D 53/75: Multi-step processes
- C07C 273/04: from carbon dioxide and ammonia
- F23J 15/006: {Layout of treatment plant}
- B01D 2257/302: Sulfur oxides
- B01D 2257/40: Nitrogen compounds
- B01D 2257/504: Carbon dioxide
- F23J 2215/10: Nitrogen; Compounds thereof
- F23J 2215/20: Sulfur; Compounds thereof
- F23J 2215/50: Carbon dioxide
- F23J 2217/102: electrostatic
- F23J 2219/40: Sorption with wet devices, e.g. scrubbers
- Y02C 20/40: of CO2
- Y02E 20/32: Direct CO2 mitigation
- Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- F23J: REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES (combustion apparatus for consuming smoke or fumes, e.g. exhaust gases, F23G7/06)
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method and apparatus is provided for cleaning flue gases from combustion plants. The method includes removing dust and removing nitrogen from flue gases, bringing flue gases into contact with an aqueous ammonia solution in the presence of an oxidizing agent whereby a reaction solution forms which contains at least ammonium carbonate, heating the reaction solution such that ammonium carbonate decomposes and carbon dioxide and ammonia transfer into the gas atmosphere, and reacting the gaseous carbon dioxide and the gaseous ammonia to form urea. The apparatus includes a device for removing nitrogen and removing dust from the flue gases, a washing device downstream of the device for removing nitrogen and removing dust, a stripper downstream of the washing device, and a urea installation downstream of the stripper.

## Claims

### Claim 1

An apparatus for cleaning flue gases from a combustion plant, including:
a device for removing nitrogen and removing dust from the flue gases,
a washing device downstream of the devices for removing nitrogen and removing dust, in which at least a portion of the flue gases is brought into contact with an aqueous ammonia solution in the presence of an oxidizing agent, whereby a reaction solution forms, which contains at least ammonium carbonate,
a stripper downstream of the washing device, in which the reaction solution is so treated that the ammonium carbonate contained in the reaction solution decomposes to form ammonia and carbon dioxide, and
a urea installation downstream of the stripper, in which ammonia and carbon dioxide are reacted to form urea.

### Claim 2 (depends on 1)

The apparatus as claimed in claim 1, wherein the apparatus further includes a device for desulfurization of the flue gases which is located upstream of the washing device.

### Claim 3 (depends on 1)

The apparatus as claimed in claim 1, wherein the apparatus further includes a device for synthesizing ammonia.

### Claim 4 (depends on 1)

The apparatus as claimed in claim 1, wherein the apparatus further includes a device downstream of the stripper for separating ammonium sulfate from the aqueous solution.

### Claim 5 (depends on 4)

The apparatus as claimed in claim 4, wherein the device for separating ammonium sulfate from the aqueous solution is a spray drying device.