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Title:
A CARBON NEUTRAL PROCESS AND RELATING APPARATUS TO PRODUCE UREA FROM MUNICIPAL OR INDUSTRIAL WASTES WITH ZERO EMISSIONS
Document Type and Number:
WIPO Patent Application WO/2017/134691
Kind Code:
A1
Abstract:
A process and apparatus for producing a nitrogen based fertilizer, urea, from carbon containing municipal and industrial wastes, comprises high temperature gasification to produce hydrogen and to make ammonia, and then combining ammonia and CO2 to produce urea. The process is able of sequestering all carbon dioxide associated to waste by a parallel production of hydrogen through water electrolysis and/or reforming bio-gas.

Inventors:
ANTONETTI ELENA (IT)
LAQUANIELLO GAETANO (IT)
SALLADINI ANNARITA (IT)
Application Number:
PCT/IT2016/000026
Publication Date:
August 10, 2017
Filing Date:
February 03, 2016
Export Citation:
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Assignee:
PROCESSI INNOVATIVI SRL (IT)
International Classes:
C07C273/10
Domestic Patent References:
WO2013095130A12013-06-27
WO2011008263A22011-01-20
WO2009091325A12009-07-23
WO2008130260A12008-10-30
Foreign References:
US6448441B12002-09-10
US5584255A1996-12-17
US6958136B22005-10-25
US6455011B12002-09-24
CN103242134A2013-08-14
US20140364517A12014-12-11
Attorney, Agent or Firm:
SARPI, Maurizio (IT)
Download PDF:
Claims:
CLAIMS

1) A Process for producing urea from carbon- matrix waste comprising the following stages:

• A HT (High temperature) gasification of a carbon- matrix waste with oxygen and steam to produce a syngas having H2/CO ratio from 0.5 to 1.5;

• A formed syngas purification comprising dust removal, cooling, removal of HC1, NH3, and, removal other impurities;

• A syngas acid gas treatment comprising a further HC1 removal, sour CO shift, H2S removal, COS hydrolysis, C02 removal and PSA to make a pure H2 stream;

• An ammonia synthesis where pure H2 and N2 are reacting to make ammonia; and

· An urea synthesis where NH3 and C02 are reacting to make urea.

2) A process according to claim 1 wherein it is further provided that the Hydrogen needed to avoid any C02 rejection into the atmosphere is produced throughout water electrolysis.

3) A process according to claim 1 wherein the carbon- matrix waste is selected from a solid municipal waste, a derived waste as RDF, urban and industrial sludge, biomass, a solid chemical waste and combinations thereof.

4) A process according to claim 1 where S in the feed is reduced and eliminated as liquid sulphur.

5) A process according to claim 1 and 2 where a minimal or zero of C02 is emitted into the atmosphere depending of the chemical composition of the carbon waste .

6) A process according to claim 1, 2 and 5 wherein no flue gases are emitted and no gaseous pollutants (zero emissions).

7) A process according to claim 1 where 2 is provided coming from an Air Separation Unit.

8) A process according to claim 1 where the gasifying agent is a mixture of oxygen and steam.

9) A process according to claim 1 wherein the gasifying agent is a mixture of air and oxygen and the final purification is carried not with PSA, but with liquid nitrogen.

10) A process according to claim 1 and 2 where the oxygen used into the HT gasification is produced partially from an Air Separation Unit and partially from water electrolysing.

11) A process according to claim 1 where the H2 required to avoid any C02 emissions is obtained by reforming bio-gas coming from anaerobic digestion of urban or industrial sludge.

12) An Apparatus for producing urea from carbon- matrix waste comprising:

• A High temperature gasification section of carbon- matrix waste with oxygen and steam to produce a syngas having H2/C0 ratio from 0.5 to 1.5;

• A syngas purification section comprising means for dust removal (106,108), cooling (110), removal of HC1, NH3 and other impurities (111) ;

· A syngas acid gas treatment section comprising means for a further HC1 removal (115), sour CO shift (118), H2S removal (119), COS hydrolysis (118), C02 removal (121) and PSA (123) to make a pure H2 stream;

• An ammonia synthesis loop where pure H2 and N2 are reacting in (126) to make ammonia; and

· An urea synthesis section (128) where NH3 and C02 are reacting to make urea.

13) The apparatus according to claim 12 wherein it is further provided an pressurizer electrolyzes (300) to produce Hydrogen and Oxygen sized to provide the Hydrogen needed to avoid any C02 rejection into the atmosphere .

14) The apparatus according to claim 12 wherein the carbon- matrix waste is selected from a solid municipal waste, a derived waste as RDF, urban and industrial sludge, biomass, a solid chemical waste and combinations thereof.

15) The apparatus according to claim 12 where S in the feed is reduced and eliminated as liquid sulphur.

16) The apparatus according to claim 1 and 2 where a minimal or zero of C02 is emitted into the atmosphere depending of the chemical composition of the carbon waste.

17) The apparatus according to claim 1, 2 and 5 wherein no flue gases are emitted and no gaseous pollutants (zero emissions) .

18) The apparatus according to claim 1 wherein N2 is provided coming from an Air Separation Unit (200) .

19) The apparatus according to claim 1 wherein the HT gasification section comprises a gasifier (103) and the gasifying agent is a mixture of oxygen and steam.

20) The apparatus according to claim 1 and 2 wherein the oxygen used into the HT gasifier is produced partially from the Air Separation Unit (200) and partially from the electrolyzer section (300) .

21) The apparatus according to claim 1 wherein the gasifying agent is a mixture of air and oxygen and the final purification is carried not with PSA (123), but with liquid nitrogen.

22) The apparatus according to claim 1 wherein the H2 required to avoid any C02 emissions is obtained by reforming bio-gas coming from anaerobic digestion of urban or industrial sludge.

Description:
"A CARBON NEUTRAL PROCESS AND RELATING APPARATUS TO

PRODUCE UREA FROM MUNICIPAL OR INDUSTRIAL WASTES WITH

ZERO EMISSIONS".

ABSTRACT

A process and apparatus for producing a nitrogen based fertilizer, urea, from carbon containing municipal and industrial wastes, comprises high temperature gasification to produce hydrogen and to make ammonia, and then combining ammonia and CO 2 to produce urea. The process is able of sequestering all carbon dioxide associated to wastes by a parallel production of Hydrogen through water electrolysis and/or reforming bio-gas.

DESCRIPTION

Field of invention:

The present invention relates generally to the conversion of carbon containing waste materials into nitrogen-based fertilizers. More specifically, the invention provides for methods, systems and apparatus for the conversion of waste materials as municipal waste, Refuse Derive Fuel and industrial wastes to urea through the production of synthesis gas as an intermediate .

Background of the invention:

Global climate change from one side and growing production of wastes on a worldwide basis from the other, are pushing for questing of new carbon neutral process where wastes can be used as feedstock.

Such processes will have also advantages over bio-diesel and ethanol production because they are not going to compete for farmland that may be needed for food production.

Processes for the production of synthesis gas (syngas) are known in the art. For example, WO 2011/008263 A2 discloses the use of plasma gasification or pyrolysis for production of syngas followed by the production of the hydrogen from syngas in a water gas shift (WGS) reactor.

WO 2009/091325 Al discloses a biomass gasification method and apparatus for production of syngas with rich hydrogen content; and US Pat n° 5,584,255 discloses a method and apparatus for gasifying organic materials. US Pat n° 6,958,136 discloses a process for the treatment of nitrogen- containing wastes streams that can generate syngas from carbon sources using alkaline metals and carbon radical formation .

WO2008130260 Al discloses a waste to liquid hydrocarbon refinery system designed to convert municipal and industrial wastes, biomass and other carbon-containing feedstock into diesel, gasoline and other products. The system involves a high temperature liquid iron bed that generates row syngas from solid and liquid feedstocks and a very high temperature plasma to convert contaminants in the row syngas into ions .

US Pat. N° 6, 455, 011 Bl discloses a method and apparatus for treating wastes into two-stage gasification which recovers metals or ash content in the wastes in such a state that they can be recycled and gases containing carbon monoxide (CO) and hydrogen gas (H 2 ) for use a synthesis gas for ammonia (NH 3 ) . CN103242134 discloses an invention relates to household garbage treatment method, where the waste is subjected to a thermal cracking to form mixed combustible gases containing CO, C0 2 , H 2 , nitrogen (N 2 ) and inert argon (Ar) by a full gasification process. The syngas is purified and separated, and then are used for synthesizing methanol and/or dimethyl eter (DME) , generating power and synthesizing urea. The system produces significant amounts of tar which be disposed or used.

US Pat. Number 2014/0364517 Al discloses a process and system for producing liquid and gas fuels and other useful chemicals from carbon containing source materials comprises cool plasma gasification and/or pyrolysis to produce syngas which in turn could be used for producing hydrocarbon, methanol, ammonia, urea and other products. The system is carbon neutral but is relatively complex and expensive, requires relatively large amount of energy for the plasma gasification.

There remains, therefore, a need for carbon neutral process, apparatus and system for produced a N- based fertilizer, as urea, from carbon containing wastes as municipal, RDF and industrial wastes. Additionally, there remains a need for a process, apparatus and system that has minimal or zero emissions, in particular C0 2 emissions.

The present invention in one or more aspects fill the afore mentioned needs in the art by providing zero emissions and energy conserving systems and processes from producing urea from a wide variety of carbon- containing source wastes.

Summary of the invention:

According to one aspect of the invention, a process and apparatus for producing urea is provided in which the process comprises high temperature (HT) gasification with oxygen and steam of a carbon waste to form syngas, purifying the formed syngas, reacting it with water to convert CO into C0 2 , remove the sulphur components and then the C0 2 , obtain pure H 2 through a PSA unit. A further H 2 production may be obtained by reforming of bio-gas from industrial/urban sludge via anaerobic digestion and/or via an electrolyzer system if required to balance completely the C0 2 availability.

The pure H 2 is added to a N 2 steam to maintain the proper ratio for synthesizing ammonia. Ammonia and all the recovered C0 2 in a suitable ratio are reacted to produce urea.

HT gasification may be performed by any suitable means, preferably a co-current fixed bed ("down draft") gasification working with oxygen and steam. High temperature means a temperature higher than 1200°C to minimize tar formation.

An advantage of HT gasification with oxygen and steam is to increase H 2 content in the syngas. Another advantage of the present invention is to maximize the

C0 2 recovery and reuse into the urea, with the possibility to have minimal or zero C0 2 emissions.

An advantage of the present process and apparatus is the ability to reduce basically to zero, eliminate, the emissions of nitrogen and sulphur (NOX and SOX) and any other pollutant present in the original carbon waste matrix, in particularly C0 2 by a parallel production of Hydrogen throughout water electrolysis.

The term "comprises/comprising" when used in this specification is taken to specify the presence or addition of one or more other features, integers, steps, components or groups thereof.

As used herein, the term "neutral" respected to emitted CO 2 means that the total carbon emission to the atmosphere neither increases nor reduced during a process. Basically the organic matrix of the waste is transformed into C0 2 which is totally stored in the form of urea.

In the context of the present invention, the term

"carbon matrix waste" refers to municipal waste, treated municipal wastes as RDF, municipal and industrial sludge and even animal tenure

Brief description of the drawings:

These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of the embodiments of the present invention, reference being made to the accompanying drawings in which:

Fig.l is a schematic representation of an apparatus and process for producing urea comprising HT

(high temperature) gasification using oxygen and steam of wastes to form syngas, purifying the formed syngas, reacting it with water to convert CO into C02, remove the sulphur components and then the C02, obtain pure H2 through a PSA unit, reacting H2 and N2 to make ammonia, and reacting ammonia and C02 to make urea; Fig. 2 is a schematic representation of a syngas transformation for the production of urea;

Fig. 3 is a schematic representation of the process from organic wastes to urea with zero emissions;

Fig. 4 is a schematic representation of the process from organic wastes + urban sludge to urea with zero emissions;

Fig. 5 is a schematic representation of the process where H 2 is provided by gasification of the organic wastes, reforming of bio-gas from urban and industrial sludge and the remainder from water electrolysis .

Detailed description of the invention:

Specific embodiments of the invention are described with reference to the accompanying drawings.

This invention may, however, be embodied in many different forms and should not be constructed as limited to the embodiments set for herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

A first stage of one embodiment according to the invention comprises the production of a syngas from a carbon containing matrix by HT gasification. A process and apparatus for the first stage of such an embodiment is shown in Fig. 2.

A feed of carbon-matrix waste 101 may be mixed with steam and/or oxygen in 102 and then introduced into the HT gasifier 103 from the top. 0 2 could be also injected at different level in the gasifier. 0 2 stream is produced in a Air Separation Unit 200 (ASU) and in pressurizer electrolyzes (300). N 2 required for the ammonia synthesis is produced in 200. Extra H 2 for ammonia synthesis is also produced in 300 if required. The gasifier is configured to produce a syngas stream, 104 and a molten slag from the bottom, 105.

The syngas stream 104 will contain mainly C0 2 , CO, H 2 S, HC1, HCN , NH 3 and dust.

The HT temperature gasification generates a temperature of approximatively 1300°C at the bottom end of the gasifier, effectively breaking down organic molecules into synthesis gas. The role of steam is to increase the H 2 content by steam reforming of methane and higher hydrocarbons.

Such gasifiers that are suitable for commercial production of syngas according to the invention are available on the market.

The temperature of the syngas leaving the gasifier may be in the range of 500-1500°C depending on the. conditions and feed materials selected. 0 2 /steam ratio will be fixed in order to achieve the proper syngas compositio .

Dust removal from syngas is provided by a cyclone 106 and eventually a bag-filter, 108. Between the two equipment a gas cooler, 107 is installed to cool down the temperature and recover the enthalpy of the flue gases by producing steam to be used in the process.

The dusted stream 109 is further cooled in a quencher absorber 110 and in a wet electrostatic precipitator (WEP) , 111, where all the acidic components HC1 or the basic ones, as NH 3 are removed together with some particulate. WEP will remove all the fog leaving the top of absorber, 110.

Pressure will controlled at the gasifier by ID fan, 112.

The syngas at the inlet of the fan will contain mainly H 2 , CO, C0 2 , HC1, H 2 S, COS and less than 5ppm of dust .

A system for performing a second stage of a process according to the invention is shown in Fig. 3. The syngas feed 113 is compressed by a compressor 114 before being conveyed into HCl removal reactor, 115. Before entering into the WGS (Water-Gas Shift) reactors 118, steam is added, and gas is preheated in 117 to the WGS proper operating temperature. WGS may consist of two or more reactors with a temperature control between them. Steam and CO react to form C0 2 and H 2 . COS is also hydrolyzed in this reactor to give CO and H 2 S. Depending of H 2 S content in the syngas the H 2 S removal system 119 may consists of a Claus unit or a red-ox system. A final ZnO bed 120 may be also required to reduce the H 2 S to less than 0.5 ppm. In order to make pure H 2 , C0 2 will be removed into section 121 and fluid purification will be carried out in a PSA, 123. Stream 122 will be routed to the urea section meanwhile stream 124 will be recycled to the gasifier and stream 125 from electrolyzer will be mixed with the row hydrogen point before the PSA unit (pressure swing adsorption) .

Stream 115 consisting of pure hydrogen will be mixed with pure nitrogen from ASU to make ammonia in the reactor 126.

The urea synthesis reaction performed in section 128 where NH 3 , stream 127 and C0 2 , stream 122, are reacted with a gas composition NH 3 /C0 2 of about 2:1 to form urea, 129.

Fig.4 depicts the entire process and urea production where H 2 is provided by gasification of the organic wastes and via the water electrolysis.

Fig. 5 depicts a slightly different process where H 2 is provided by gasification of the organic wastes, reforming of bio-gas from urban and industrial sludge and the remainder from water electrolysis.