NO20150574A1 - Reduction of nox emission during fertilizer production - Google Patents
Reduction of nox emission during fertilizer production Download PDFInfo
- Publication number
- NO20150574A1 NO20150574A1 NO20150574A NO20150574A NO20150574A1 NO 20150574 A1 NO20150574 A1 NO 20150574A1 NO 20150574 A NO20150574 A NO 20150574A NO 20150574 A NO20150574 A NO 20150574A NO 20150574 A1 NO20150574 A1 NO 20150574A1
- Authority
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- Prior art keywords
- gaseous effluent
- ozone
- scrubber
- fertilizer production
- process according
- Prior art date
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- 239000003337 fertilizer Substances 0.000 title claims description 69
- 238000004519 manufacturing process Methods 0.000 title claims description 60
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 91
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 82
- 238000000034 method Methods 0.000 claims description 48
- 239000007789 gas Substances 0.000 claims description 47
- 239000000203 mixture Substances 0.000 claims description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 35
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 33
- 229910017604 nitric acid Inorganic materials 0.000 claims description 33
- 238000007254 oxidation reaction Methods 0.000 claims description 30
- 230000003647 oxidation Effects 0.000 claims description 22
- 229910019142 PO4 Inorganic materials 0.000 claims description 20
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 20
- 239000010452 phosphate Substances 0.000 claims description 20
- 230000002378 acidificating effect Effects 0.000 claims description 15
- 102100029133 DNA damage-induced apoptosis suppressor protein Human genes 0.000 claims description 13
- 101000918646 Homo sapiens DNA damage-induced apoptosis suppressor protein Proteins 0.000 claims description 13
- RJIWZDNTCBHXAL-UHFFFAOYSA-N nitroxoline Chemical compound C1=CN=C2C(O)=CC=C([N+]([O-])=O)C2=C1 RJIWZDNTCBHXAL-UHFFFAOYSA-N 0.000 claims description 13
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 12
- ZWWCURLKEXEFQT-UHFFFAOYSA-N dinitrogen pentoxide Inorganic materials [O-][N+](=O)O[N+]([O-])=O ZWWCURLKEXEFQT-UHFFFAOYSA-N 0.000 claims description 12
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 9
- 239000000428 dust Substances 0.000 claims description 9
- 150000003839 salts Chemical class 0.000 claims description 8
- 238000000184 acid digestion Methods 0.000 claims description 7
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 claims description 7
- 239000001569 carbon dioxide Substances 0.000 claims description 6
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 5
- 238000005201 scrubbing Methods 0.000 claims description 5
- 238000002347 injection Methods 0.000 claims description 4
- 239000007924 injection Substances 0.000 claims description 4
- 238000004458 analytical method Methods 0.000 claims description 3
- 230000001590 oxidative effect Effects 0.000 claims description 3
- 239000007800 oxidant agent Substances 0.000 claims description 2
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 claims description 2
- 229910002089 NOx Inorganic materials 0.000 description 17
- 238000006243 chemical reaction Methods 0.000 description 16
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 15
- GQPLMRYTRLFLPF-UHFFFAOYSA-N nitrous oxide Inorganic materials [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 13
- 230000029087 digestion Effects 0.000 description 11
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 239000002253 acid Substances 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000006227 byproduct Substances 0.000 description 6
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 5
- 125000004433 nitrogen atom Chemical group N* 0.000 description 5
- 239000001117 sulphuric acid Substances 0.000 description 5
- 235000011149 sulphuric acid Nutrition 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- 229910052586 apatite Inorganic materials 0.000 description 4
- LZDSILRDTDCIQT-UHFFFAOYSA-N dinitrogen trioxide Chemical compound [O-][N+](=O)N=O LZDSILRDTDCIQT-UHFFFAOYSA-N 0.000 description 4
- 150000002823 nitrates Chemical class 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- VSIIXMUUUJUKCM-UHFFFAOYSA-D pentacalcium;fluoride;triphosphate Chemical compound [F-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O VSIIXMUUUJUKCM-UHFFFAOYSA-D 0.000 description 4
- IOVCWXUNBOPUCH-UHFFFAOYSA-N Nitrous acid Chemical compound ON=O IOVCWXUNBOPUCH-UHFFFAOYSA-N 0.000 description 3
- 150000007513 acids Chemical class 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- WFPZPJSADLPSON-UHFFFAOYSA-N dinitrogen tetroxide Inorganic materials [O-][N+](=O)[N+]([O-])=O WFPZPJSADLPSON-UHFFFAOYSA-N 0.000 description 3
- 239000002367 phosphate rock Substances 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 238000010792 warming Methods 0.000 description 3
- 238000010306 acid treatment Methods 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000001311 chemical methods and process Methods 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000005431 greenhouse gas Substances 0.000 description 2
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 2
- 238000002329 infrared spectrum Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 235000015097 nutrients Nutrition 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 2
- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 2
- 230000002285 radioactive effect Effects 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 239000011949 solid catalyst Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000005696 Diammonium phosphate Substances 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 1
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 description 1
- 229910000388 diammonium phosphate Inorganic materials 0.000 description 1
- 235000019838 diammonium phosphate Nutrition 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 description 1
- 229910000396 dipotassium phosphate Inorganic materials 0.000 description 1
- 235000019797 dipotassium phosphate Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 235000019837 monoammonium phosphate Nutrition 0.000 description 1
- 239000006012 monoammonium phosphate Substances 0.000 description 1
- 229910000402 monopotassium phosphate Inorganic materials 0.000 description 1
- 235000019796 monopotassium phosphate Nutrition 0.000 description 1
- 231100001143 noxa Toxicity 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 150000003112 potassium compounds Chemical class 0.000 description 1
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 1
- 239000004323 potassium nitrate Substances 0.000 description 1
- 235000010333 potassium nitrate Nutrition 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 210000002345 respiratory system Anatomy 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/60—Simultaneously removing sulfur oxides and nitrogen oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
- C01B21/38—Nitric acid
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/003—Arrangements of devices for treating smoke or fumes for supplying chemicals to fumes, e.g. using injection devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Biomedical Technology (AREA)
- General Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Mechanical Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Inorganic Chemistry (AREA)
- Fertilizers (AREA)
Description
TECHNICAL FIELD
The invention relates to the technical field of NOxremoval from gaseous effluents. The invention more specifically relates to the removal of NOxfrom gaseous effluents generated in the production of fertilizer. This gaseous effluent has a specific composition with NOx, rich in N02. The invention is advantageous for pollution control in fertilizer production.
BACKGROUND
During the production of fertilizers, NOxgasses are formed as an unwanted side product. NOxcan lead to acid rain formation. Addition of urea, a well-known method of reducing NOxemissions, decreases NOxproduction during the production of fertilizer but increases N20 emission. N20 is a greenhouse gas, affecting global warming much more than C02. The effect of these gasses on global warming is expressed by a global-warming potential or GWP value for each gas, indicating how many times the impact of 1 ton of C02needs to be multiplied by to have the same impact as 1 ton of that gas and this for a period of 100 years after the gas has been released in the atmosphere. For N20, the GWP(i00yeano is equal to 298. Therefor other methods for reducing NOX are needed that do not increase the emission of other environmentally harmful gasses orChemicals.
As N02is the main component of the NOxthat is released by fertilizer production, typically for the nitrophosphate process, especially the N02needs to be eliminated from the gaseous effluent produced by fertilizer production before the gaseous effluent can be released in the atmosphere. Gaseous effluents from fertilizer plants are relatively cold and typically also comprise dust particles, acid droplets, hydrofluoric acid and water; all of which can cause complications.
From the prior art, methods are known to chemically react NOxfrom fertilizer plant off gasses, based on selective catalytic reduction (SCR). The drawback of these methods is that expensive catalyst needs to be used; catalyst regeneration cycles need to be carried out. Hence, there still is a desire for alternatives.
Methods to treat NOxcontaining gaseous effluents of other industrial processes have been described in the prior art, with the difference that the NOxcomposition is rich in NO and low in N02. Not many components are present in the gaseous effluents that interfere with the oxidation reaction. Typically NOxis removed from gaseous effluents by alkaline scrubbing. The gaseous effluent produced by fertilizer production comprises a large amount of acidic components, preferably nitric acid, hydrochloric acid, hydrofluoric acid, Silicon tetrafluoride and carbon dioxide (C02). These acidic components will react with the alkaline medium in the scrubber, and as a consequence large amounts of alkaline medium are needed, producing large amounts of side products. Therefore, this technique is unsuitable to be used to reduce NOxpollution during fertilizer production.
US 6,231,824 for instance, describes a 3-step process for the reduction of NOxin a furnace flue gas. First, the gaseous effluent is passed through a solid catalyst where NO is converted to N02. This is followed by the oxidation of N02by ozone to N205before a wet scrubber removes the N205from the gaseous effluent. The oxidation reaction is carried out with a large excess of ozone, namely in excess of 1.5 equivalents as theoretical 0.5 equivalents should be sufficient. This process is unsuitable for the treatment of low temperature gaseous effluents from a fertilizer plant that comprise dust particles that can clog up the solid catalyst and droplets of acid that can poison the catalyst.
US 5,985,223 describes the removal of SOx and NOxfrom a gaseous effluent generated by a metal pickling process. The composition of the NOxis 60 to 65 vol% NO and 35-40 vol% N02. The gaseous effluent is passed through a first alkaline scrubber to remove at least part of the N02before oxidation is carried out by ozone. Finally the gaseous effluent is passed through a second alkaline scrubber to remove N205. Passing through the first scrubber makes the NOxcomposition richer in NO. The composition obtained is not provided. The use of two alkaline scrubbers makes the removal of NOxfrom a gaseous effluent complex and expensive. Furthermore, the whole instaNation takes up a large volume, making it difficult to amend existing plants.
It is therefore an object of the invention to overcome at least some of the problems mentioned above for the removal of NOxfrom fertilizer production gaseous effluents. The invention aims to develop a method and installation that can be used specifically for the removal of NOxfrom gaseous effluents generated in fertilizer production.
SUMMARY OF THE INVENTION
In a first aspect, the invention provides in a process for the removal of NOxfrom a gaseous effluent generated in the production of fertilizer, comprising the steps of: a) contacting the gaseous effluent with 0.7 to 1.7 equivalents ozone to every 1 equivalent of NOx present in said gaseous effluent for 3 to 15 seconds, providing in a resultant gas mixture, wherein NO and N02present in the NOxare oxidized to higher nitrogen oxides; and b) passing the resultant gas mixture through a wet scrubber thereby removing the higher nitrogen oxides.
A method according to the invention is advantageous as with ozone treatment of the off gasses of the fertilizer production a way is provided to reduce NOx emissions without increasing N20 emissions.
The term "fertilizer" refers to a material from an at least partially synthetic origin that is intended to be applied to soil or plants to supply one or more plant nutrients. The fertilizer can be of the single nutrient type, for example a nitrate salt, or from the multi-nutrient type. Examples of multi-nutrient type fertilizers are: NP fertilizers preferably monoammonium phosphate or diammonium phosphate, NK fertilizers preferably potassium nitrate, PK fertilizers preferably a monopotassium phosphate or dipotassium phosphate, or NPK fertilizer, comprising nitrogen, phosphorus and potassium compounds.
The term "gaseous effluent" refers to gas molecules, dust particles, droplets that are released from and during a chemical or physical process.
The term "NOx" refers to the sum of all the mono-nitrogen oxides present in the gaseous effluent.
The following chemical formulas are used:
- NO, meaning nitrogen oxide; - N02, meaning nitrogen dioxide; - N03, meaning nitrogen trioxide; - N203, meaning dinitrogen trioxide; - N204, meaning dinitrogen tetroxide;
- N205, meaning dinitrogen pentoxide.
The term "higher nitrogen oxides" refers to nitrogen oxides as product from an oxidation reaction wherein the nitrogen atom has a higher oxidation state than the nitrogen atom in the reagent. The term is always relative to the reagent that is oxidised. For example, N205, where the nitrogen atom has an oxidation state of +5, is a higher nitrogen oxide of N02, where the nitrogen atom has an oxidation state of +4, and N02is a higher nitrogen oxide of NO, where the nitrogen atom has an oxidation state of +2.
The term "contacting" means adding one gas mixture to another and letting the two gas mixture mix with each other. This can achieved by injecting one gas mixture in the other. The mixing can be passively, by the turbulence caused by the addition of the gas, or actively, where a mechanical movement causes the gasses to mix with each other.
The gaseous effluent generated in the production of fertilizer has a composition that is different from other chemical processes releasing NOx. The gaseous effluent generated in fertilizer production comprises NOx, and these NOxhave a composition rich in N02, preferably 80 to 100 mole% N02and 0 to 20 mole% NO, more preferably 90 to 95 mole % N02and 5 to 10 mole % NO. In addition to NOx, the gaseous effluent also comprises water vapour, hydrogen fluoride, Silicon tetrafluoride, carbon dioxide, droplets of nitric acid and/or dust. The specific composition of the gaseous effluent and the variation of this composition during the production of fertilizer requests specific reaction conditions. As the NOxin the gaseous effluent is rich in N02, less ozone needs to be used compared to other gaseous effluents with NOxcompositions that are rich in NO known from the prior art. The exact amount of ozone that needs to be used can't be deduced based on the NOxcomposition alone, other elements preferably other components in the gaseous effluent and extern a I factors preferably humidity and external temperature need to be tåken into account.
The ozone is contacted to the gaseous effluent in a molar ratio of ozone over NOxin the gaseous effluent of 0.7 to 1.7, preferably 0.8 to 1.6, more preferably 0.9 to 1.5, even more preferably 1.0 to 1.4 and most preferably 1.1 to 1.3, typically 1.2.
Molar ratios in this region are an equilibrium between enough ozone to drive the oxidation of NOxforward in the presence of all the other components in the gaseous effluent and minimizing the amount of ozone that needs to be generated and is not used in the oxidation reaction itself. The excess of ozone after the oxidation needs to be removed from the gaseous effluent requesting energy and resources. This and the fact that the ozone needs to be generated at first makes the use of a large excess of ozone cost-inefficient.
In a preferred embodiment of a process according to the invention, the fertilizer production is the acid digestion of phosphate ore. Preferably the fertilizer is produced by nitric acid treatment of apatite. In another preferred embodiment, the dissolution or digestion of phosphorous containing rocks is carried out by treatment with nitric acid or nitric acid in combination with other acids, typically, but not exclusively phosphoric acid or sulphuric acid. This process is called the mixed acid digestion process.
In a possible embodiment of a process according to the invention, the higher nitrogen oxide is N205.
This is advantageous since N205can be easily removed from the gaseous effluent by a wet scrubber.
In an advantageous process embodiment according to the invention, the medium used in the wet scrubber is reclaimed water, meaning water that have been used before. More preferably the water has been used to dean at least parts of the fertilizer production plant, preferably reactors, pipes or the floors of the plant. Salts and other components related to fertilizer production will be dissolved in said water. Most preferably, the reclaimed water is acidic.
In an advantageous process embodiment according to the invention, the wet scrubber is an acidic wet scrubber.
A first advantage of using an acidic solution in the scrubber is that not all the acidic components that are present in the gaseous effluent generated in fertilizer production will react and/or be absorbed by the medium. The gaseous effluent comprises large amounts of carbon dioxide, hydrochloric acid, hydrofluoric acid or Silicon tetrafluoride. The acidic medium will still absorb the higher nitrous oxides, but less side products will be formed in the acidic medium. Eventually this results in less medium that needs to be used in the scrubber and less side products that needs to be disposed of.
In a possible embodiment according to the invention, the gaseous effluent comprises at least one of the following list: water vapour, hydrogen fluoride, Silicon tetrafluoride, nitric acid or dust.
The advantage thereof is that the gaseous effluent can be directly treated in the method without any purification steps in advance. Another advantage is that the method can be carried out in almost every existing wet scrubber modified in that an ozone injection point is fitted in the gaseous effluent supply line to the scrubber. If a pre-treatment was needed, large structures will need to be positioned between the source of the gaseous effluent and the scrubber. This makes it difficult to modify existing installations.
In a preferred process embodiment according to the invention, the scrubber in step b) is the only scrubber used for the removal of NOxfrom the gaseous effluent.
This has the advantage that only one scrubber needs to be installed. It reduces the running costs of the removal of NOxas only one scrubber needs to be maintained and provided with water or scrubbing solution. This also reduces the amount of water or scrubbing solution that needs to be treated or purified after it has fulfilled its role in the scrubber. The solution provided is cost effective and environmentally friendly.
In an even more preferred embodiment, the scrubber solution, which is a concentrated acidic liquid containing nitrates, is recycled into the fertilizer production process. By doing so, there is no waste stream.
In an embodiment of a process according to the invention, nitric acid, nitrous acid or a salt thereof is formed in step b).
The formation of nitric acid, nitrous acid or a salt hereof has the advantage that these species have a high solubility in water and therefor can be removed effectively from the gaseous effluent by a wet scrubber. The water comprising the components can be used as an acid solution or the salts can be used as fertilizer.
In the process according to the invention, the time between the gaseous effluent being mixed with the ozone of step a) and entry of the resultant gas mixture in the wet scrubber of step b) is 3 to 15 seconds, more preferably 4 to 13 seconds, even more preferably 5 to 11 seconds, and most preferably 7 to 9 seconds, typically 8 seconds.
In a preferred embodiment of a process according to the invention, the temperature in step a) is 130 °C or less.
A temperature below 130 °C reduces the destruction of ozone. Therefore more ozone is available for oxidation of NOx- At lower temperatures less ozone needs to be generated to obtain the same efficacy of the removal of NOX from the gaseous effluent. A higher temperature also pushes the reaction equilibrium towards the reagents side, promoting the decomposition of N205back towards N02.
In an advantageous embodiment of a process according to the invention, a gas analyser measures the concentration of NOxin the gaseous effluent and regulates the amount of ozone added to the gaseous effluent in step a) on the basis of the NOx concentration measured.
Measuring the concentration of NOxin the gaseous effluent determines the amount of NOxpresent in the gaseous effluent at a certain point in time. This information is used to determine how much ozone needs to be added to the gaseous effluent at that point in time. This has the advantage that at any point in time the correct amount of ozone is added to the gaseous effluent so that a certain ratio of moles of ozone to the moles of NOxis maintained. This prevents the over or under dosing of ozone, preventing ozone spillage or incomplete oxidation of the NOx.
In a second aspect, the invention provides the use of ozone as an oxidant for the oxidation of NOxin a gaseous effluent, wherein the gaseous effluent is generated in fertilizer production.
The use of ozone has the advantage that it can be generated on the spot and noChemicals need to be stored, supplied or disposed of.
In a preferred use according to the invention, NOxis removed from a gaseous effluent generated in the fertilizer production by means of oxidation by ozone of NO and N02present in the NOxto higher nitrogen oxides, providing in a resultant gas mixture, and scrubbing the resultant gas mixture by means of a wet scrubber thereby removing the higher nitrogen oxides
NOxgets oxidised by ozone to higher nitrogen oxides. These higher nitrogen oxides are more water soluble and can be removed easily by a wet scrubber.
In an advantageous use according to the invention, the fertilizer production is the acid digestion of phosphate ore; preferably nitric acid treatment of apatite. In another preferred embodiment, the fertilizer production is the dissolution or digestion of phosphorous containing rocks, carried out by treatment with nitric acid or nitric acid in combination with other acids, typically, but not exclusively phosphoric acid or sulphuric acid. Most preferred, the fertilizer production is the digestion of phosphate ore with nitric acid as the only acid used.
The digestion of phosphate ore is one of the main processes to obtain phosphate for fertilizer production, especially in the production of NP and NPK fertilizers. The main source of phosphate ore is apatite, and preferably this apatite is treated with nitric acid. The use of nitric acid in the digestion of phosphate ore is favoured over the use of sulphuric acid as no phosphogypsum is formed. The phosphogypsum has no economic value, and due to its weakly radioactive nature precautions need to be tåken for the disposal of it.
The ozone is used in a molar ratio of ozone over NOxin the gaseous effluent of 0.7 to 1.7, preferably 0.8 to 1.6, more preferably 0.9 to 1.5, even more preferably 1.0 to 1.4 and most preferably 1.1 to 1.3, typically 1.2.
Molar ratios in this region are an equilibrium between enough ozone to drive the oxidation of NOxforward in the presence of all the other components in the gaseous effluent and minimizing the amount of ozone that needs to be generated and is not used in the oxidation reaction itself. The excess of ozone after the oxidation needs to be removed from the gaseous effluent requesting energy and resources. This and the fact that the ozone needs to be generated at first makes the use of a large excess of ozone cost-inefficient.
In a use according to the invention, the gaseous effluent comprising the oxidation products of NOxis fed to a wet scrubber. The oxidation products of NOxare higher nitrogen oxides, preferably N205. These higher nitrogen oxides are much more water soluble than NO and N02.
In a wet scrubber, the water from the scrubber will react with the oxidation product of NOxand dissolve the oxidation products removing them from the gaseous effluent. Preferably N205will react with water to form nitric acid that will dissolve in the water. If an alkaline base is present in the water, a nitrate salt will be formed that can be used as fertilizer. The alkaline base however will also react with other acidic components in the gaseous effluent, causing larger amounts of side product to form. Therefore in a more preferred use, an acidic wet scrubber is used. The acidic medium will still absorb the higher nitrous oxides, but will not or less absorb the basic or weak acidic components present in the gaseous effluent, typically carbon dioxide. During the fertiliser production process large amount of C02are produced and an alkaline scrubber would absorb these large amounts of C02, using large volumes of scrubber solution and generating large amounts of waste products.
In a preferred use, the medium used in the wet scrubber is reclaimed water, meaning water that have been used before. More preferably the water has been used to dean at least parts of the fertilizer production plant, preferably reactors, pipes or the floors of the plant. Salts and other components related to fertilizer production will be dissolved in said water. Most preferably, the reclaimed water is acidic.
In a third aspect according to the invention, a fertilizer production plant is provided, comprising: a reactor;
a gas outlet, connected to the reactor;
a wet scrubber, configured to receive a NOx-containing gaseous effluent
produced in the reactor;
a connector, connecting the gas outlet and the scrubber, configured to
transport the gaseous effluent;
wherein an ozone generator is connected to the connector or the wet scrubber, configured to inject ozone into the gaseous effluent.
In a preferred embodiment of a fertilizer production plant according to the invention a gas analyser is present in the gas outlet, the connector or a final stack connected to said wet scrubber, and is configured to analyse at least part of the composition of the gaseous effluent and control the ozone injection on the basis of the NOxconcentration measured.
DESCRIPTION OF FIGURES
FIG. 1 depicts the N02emission during a batch digestion of phosphate ore with nitric acid. FIG.2 shows a diagram of a fertilizer production plant according to an embodiment of the invention. FIG. 3 depicts infrared spectra of the gaseous effluent before and after reaction with ozone and passing through the wet scrubber.
DETAILED DESCRIPTION OF THE INVENTION
Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.
The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.
The invention relates to the removal of NOxfrom gaseous effluent generated in fertilizer production, more preferably NPK fertilizer production, and most preferably acid digestion of phosphate ore, using ozone to treat the gaseous effluent, resulting in a resultant gas mixture, thereby oxidizing NO and N02present in the NOxto higher oxides, and furthermore using a wet scrubber through which the resultant gas mixture is passed, thereby removing the higher nitrogen oxides.
Acid digestion of phosphate ore, also called phosphate rock, is a well-known process in the production of fertilizers. Phosphate ore is treated with nitric acid. The process can be represented by reaction (I):
NOxis released during this reaction as a main side product. And this NOxhas a composition with a high amount of N02, typically of 80 to 100 mole% N02and 0 to 20 mole% NO, more preferably 90 to 95 mole % N02and 5 to 10 mole % NO. The treatment of phosphate rock with nitric acid as described above is the preferred process for the production of NP or NPK fertilizer, as in one reaction phosphate as well as nitrate salt are formed simultaneously. The main drawback is however the amounts of NOxthat are produced during this process. The use of sulphuric acid in the digestion of phosphate ore does not produce NOx, but it produces one equivalent of gypsum, also referred to as phosphogypsum, as it comes from the digestion of phosphate ore. This phosphogypsum has economically no value, even more because of weakly radioactive nature of phosphogypsum special precautions need to be tåken in the disposal of it and most of the time the phosphogypsum is landfilled. Hence again, the use of nitric acid for at least partially replacing sulphuric acid in the digestion of phosphate ore is preferred.
The NOxof the gaseous effluent released during fertilizer production has a composition of preferably 80 to 100 mole% N02and 0 to 20 mole% NO, more preferably 90 to 95 mole % N02and 5 to 10 mole % NO., which is a different NOxcomposition than other chemical processes where NOxis released. For instance, combustion of fossil fuels in the presence of air produces a NOxcomposition with large amounts of NO, up to 95 mole% NO, and small amounts of N02, up to 5 mole%. Pickling metals also releases NOx, but with a larger N02amount, up to 35 - 40 mole% N02and up to 60 - 65 mole% NO. In the production of nitric acid, the NOxcomposition released comprises around 50 mole% NO and 50 mole% N02. Hence, for the gaseous effluent released during fertilizer production with a NOxcomposition of at least 80 mole% N02, and other impurities preferably dust, droplets, hydrogen fluoride, Silicon tetrafluoride and large amounts of water vapour, different reaction conditions are needed for an effective removal of NOxfrom the gaseous effluent. Theoretically, Vi mole of ozone is needed to convert one mole of N02into N205. Hence a NOxcomposition with a high percentage N02needs less ozone than a NOxcomposition with a large fraction of NO. In practice, an excess of ozone is needed to obtain a satisfying conversion from NOxto higher nitrogen oxides. These higher nitrogen oxides are more soluble and/or more reactive with water. Hence, these higher nitrogen oxides can be easily removed from the gaseous effluent with a wet scrubber.
Using a large excess of ozone, for example more than two equivalent, will oxidise all the NOxpresent in the gaseous effluent, but the unreacted ozone needs to be destroyed before the gaseous effluent can be released in the atmosphere, this because ozone is harmful to humans and other living organisms, affects the respiratory system and is a greenhouse gas itself. Ozone reacts with other compounds in the atmosphere and can form pollutants that can be more harmful than the ozone itself. Overall, using a large excess of ozone is not cost efficient, as resources and energy need to be used to produce ozone that largely will be destroyed without being used in a desired chemical reaction. The majority of the ozone produced is to push the oxidation reaction of NOxto completion. This puts extra pressure on the environment as more resources and energy need to be used for as well production and destruction of ozone. Therefore, the amount of ozone needed to oxidise NOxin the gaseous effluent needs to be optimised to make the whole removal process economical and environmentally viable.
The amount of excess ozone that is needed in practice compared to the theoretical amount can't be deduced from other NOxcompositions. The excess depends on other components present in the gaseous effluents, some of these components can be oxidised as well or interfere with the oxidation of NOx. The amount of water vapour in the gaseous effluent, the amount of dust particles, the temperature of the gaseous effluent all have an impact on the speed and yield of the oxidation reaction. Furthermore, the composition of the gaseous effluent is not a constant, fluctuations in NOxand other components can vary quite significantly during one process. Especially for batch processes, the composition of the gaseous effluent at the beginning of the process is completely different from the composition at the end of the process. Also, the removal of NOxfrom the gaseous effluent needs to be robust, meaning that external factors preferably air humidity and external temperature don't disturb the efficacy of the removal process. Changes in external factors can't lower the efficacy of the removal of NOxin the gaseous effluent under preferably 70 %, more preferably under 75 %, even more preferably under 80 % and most preferably under 85 %. Efficacy is expressed as the percentage of mole NOxthat has been removed from the gaseous effluent over the moles NOxthat were initially present.
The higher nitrogen oxide preferably is dinitrogen pentoxide or N205. N205reacts with water to form nitric acid, and is therefore removed from the gas phase as the nitric acid is dissolved by the water in the scrubber. N205is the oxide of nitrogen with a fast reaction rate or high solubility (see table 1), and is therefore the most preferred oxide for fast removal of nitrogen oxides from a gaseous effluent. The reaction of N205with water can be represented by reaction (II):
The wet scrubber used in this process is preferably a scrubber using reclaimed water or a scrubber with an acidic medium.
The gaseous effluent preferably comprises at least one of the following list: sulphur oxides, water vapour, hydrogen fluoride, Silicon tetrafluoride, nitric acid, carbon dioxide or dust.
Preferably, only one wet scrubber is used for the removal of NOxfrom the gaseous effluent.
During the passage of the resultant gas mixture through the wet scrubber, preferably nitric acid is formed as shown in reaction (III). If any unreacted N02is present at this stage, the N02will form a mixture of nitrous and nitric acid as shown in reaction (IV).
The time between the gaseous effluent being mixed with the ozone and the entry in the wet scrubber is 3 to 15 seconds, preferably 4 to 13 seconds, more preferably 5 to 11 seconds, and most preferably 7 to 9 seconds, typically 8 seconds. The time between the gaseous effluent being mixed with the ozone and the entry in the wet scrubber is also called the residence time. Experiments have shown that at least 3 seconds residence time is needed to produce a satisfying result, meaning an efficacy to remove NOxfrom the gaseous effluent of at least 80 %. Long reaction times, longer than 15 seconds, do not increase the efficacy anymore.
The temperature applied in the treatment of the gaseous effluent comprising NOxproduced during fertilizer production with ozone preferably is 130 °C or less, more preferably 110 °C or less, even more preferably 100°C or less and most preferably 80 °C or less.
In order to measure the concentration of NOx in the gaseous effluent, a gas analyser is provided to measure the concentration of NOxin the gaseous effluent and regulates the amount of ozone added to the gaseous effluent in step a) on the basis of the NOx concentration measured.
In the example provided in Fig. 2, a fertilizer production plant according to the invention is shown. This fertilizer production plant comprises: a reactor 1;
a gas outlet 2, connected to the reactor 1;
a wet scrubber 5, configured to receive a NOx-containing gaseous effluent
producible in the reactor 1;
a connector 4, connecting the gas outlet 2 and the scrubber 5, configured to
transport the gaseous effluent;
wherein an ozone generator 3 is connected to the connector 4 or the wet scrubber 5, configured to inject ozone into the gaseous effluent.
Preferably, a gaseous effluent that can be formed in the reactor 1 can only leave the reactor 1 via the gas outlet 2.
A connector 4 connects the gas outlet 2 to a wet scrubber 5 in a way that a gaseous effluent that can be formed inside the reactor 1 can reach a wet scrubber 5. Reactor 1 can be filled with reactants 11 needed in the fertilizer production process and is foreseen with an overflow 7, preventing reactants or reaction mixture to enter into the gas outlet 2.
An ozone generator 3 is connected to the connector 4, and this in a way that the ozone that can be generated by the ozone generator 3 can be injected into the connector 4 where the ozone can mix and react with the gaseous effluent that can travel through the connector 4.
The ozone generator 3 makes it possible to oxidise the NOxto higher nitrogen oxides. The length of the connector 4 between where the ozone is injected 12 and the gas inlet 13 of the wet scrubber 5 determines together with the flow rate of the gaseous effluent the reaction time or residence time. Preferably length of the connector 4 is designed that the residence time is 3 to 15 seconds, more preferably 4 to 13 seconds, even more preferably 5 to 11 seconds, and most preferably 7 to 9 seconds, typically 8 seconds. This way preferably 70 %, more preferably 80 %, even more preferably 90 % and most preferably 100 % of the NOxare oxidised to a higher nitrogen oxide by the time the gaseous effluent reaches the wet scrubber 5. The wet scrubber 5 makes it possible to remove the higher nitrogen oxides efficiently from the gaseous effluent as these higher nitrogen oxides have a high solubility in the scrubber medium 8 or react with the water in the scrubber medium 8 to form water soluble salts or acids. The scrubber medium 8 comprising the nitric acid or salt can leave the wet scrubber 5 via medium outlet 9. Fresh and/or reused scrubber medium 8 can be introduced in the wet scrubber 5 via medium inlet 10. Overall, with the fertilizer production plant from the invention nitric acid can be used for the production of fertilizer, and more preferably the digestion of phosphate ore with no or strongly reduced NOxemissions. Preferably 70 %, more preferably 80 %, even more preferably 90 % and most preferably 100 % of the NOxare removed from the gaseous effluent that is generated in fertilizer production and leaves the production plant via final stack 6.
Alternatively, the ozone generator 3 can be directly connected to the wet scrubber 5, and this in a way that the ozone generated by the ozone reactor can be injected in the wet scrubber 5 and mix there with the gaseous effluent. The oxidation will still work but the large amounts of water present in the scrubber will slow down the oxidation reaction.
Preferably, a gas analyser 14 is present in the gas outlet 2, the connector 4 or a final stack 6 connected to said wet scrubber 5, and is configured to analyse at least part of the composition of the gaseous effluent and control the ozone injection on the basis of the NOxconcentration measured.
The gas analyser 14 makes it possible that at least the concentration of NOxis determined in the gaseous effluent that can be produced in the reactor 1. This information can be used to control the amount of ozone that is generated by the ozone generator 3 and is injected in the gaseous effluent. This way a predetermined ratio of ozone to NOxcan be maintained, and is always the right amount of ozone present in the gaseous effluent and is less ozone wasted at point that the concentration of NOxin the gaseous effluent drops.
The invention is further described by the following examples which illustrate the invention.
EXAMPLES
Example 1:
Figure 1 depicts the N02emission during a batch digestion of phosphate ore with nitric acid. The x-axis represents time since addition of nitric acid to the phosphate rock, expressed in minutes. The y-axis represents the concentration of N02in the gaseous effluent, expressed in parts per million or ppm. It is clear that in the first 20 minutes a much higher concentration of N02is released than after 20 minutes. N02emission stabilises from 20 minutes onwards. Even though the same reaction conditions were used for different batches (see different symbols on the figure), it can be seen that the concentration is still different for every batch.
Example 2:
Table 1 shows the different Henry's law constants for the different oxides from nitrogen. The Henry's law constant of a compound is proportional to the solubility of the compound. The Henry's law constant and thus the solubility of N205is two orders of magnitude higher than the one of N02and three orders of magnitude higher than the one of NO. The Henry's law constant of nitric acid or HN03is extremely high compared to the ones of the oxides.
Example 3
Figure 2 shows a diagram of a fertilizer production plant according to an embodiment of the invention. A reactor 1 suitable to contain reactants 11 ,phosphate ore and nitric acid, is foreseen from a gas outlet 2 and an overflow 7. The gas outlet 2 is connected to a wet scrubber 5 via a connector 4. Gaseous effluent can travel from the reactor 1 through the connector 4 to the wet scrubber. To the connector 4, a gas analyzer 14 is connected that can analyze the composition of the gaseous effluent traveling through the connector 4. Downstream from the gas analyzer 14, an ozone generator 3 is connected to the connector 4, capable to inject ozone in the connector 4 and in the gaseous effluent. The connector 4 is attached to wet scrubber 5 via the gas inlet 13. The wet scrubber 5 itself comprises a scrubber medium 8 that can leave the wet scrubber 5 via a medium outlet 9. The scrubber medium 8 enters the scrubber via medium inlet 10. The gaseous outlet can leave the scrubber via the final stack 6, preferably free of NOx.
Example 4
Table 2 shows the efficacy of oxidation depending on the molar ratio of ozone over NOxpresent in a gaseous effluence.
Example 5
Figure 3 depicts infrared spectra of the gaseous effluent before and after reaction with ozone and passing through the wet scrubber. The absorbance band of N02at 1628 cm<1>is absent in the gaseous effluent after treatment with ozone. The C02peaks have a similar surface area before and after the addition of ozone, this indicates that the changes observed are not due to dilution of the gas mixture.
Claims (16)
1. A process for removal of NOxfrom a gaseous effluent generated in the production of fertilizer, comprising the steps of: a) contacting the gaseous effluent with 0.7 to 1.4 equivalents ozone to every 1 equivalent of NOx present in said gaseous effluent for 3 to 15 seconds, providing in a resultant gas mixture wherein NO and N02present in the NOxare oxidized to higher nitrogen oxides; and, b) passing the resultant gas mixture through a wet scrubber thereby removing the higher nitrogen oxides.
2. Process according to claim 1, wherein the gaseous effluent generated in the production of fertilizer has a NOxcomposition of 80 to 100 mole% N02and 0 to 20 mole% NO.
3. Process according to any one of previous claims, wherein the fertilizer production is by acid digestion of phosphate ore.
4. Process according to any one of previous claims, wherein the higher nitrogen oxide is N205.
5. Process according to any one of previous claims, wherein the wet scrubber is an aqueous acidic scrubber.
6. Process according to any one of previous claims, wherein the gaseous effluent comprises at least one of the following list: sulphur oxides, water vapour, hydrogen fluoride, Silicon tetrafluoride, nitric acid, carbon dioxide or dust.
7. Process according to any one of previous claims, wherein the scrubber in step b) is the only scrubber used for the removal of NOxfrom the gaseous effluent.
8. Process according to any one of previous claims, wherein nitric acid or a salt thereof is formed in step b).
9. Process according to any one of previous claims, wherein the temperature in step a) is 130 °C or less.
10. Process according to any one of previous claims, wherein a gas analyser measures the concentration of NOxin the gaseous effluent and regulates the amount of ozone added to the gaseous effluent in step a) on the basis of the NOx concentration measured.
11. Use of ozone as an oxidant in the removal of NOxfrom gaseous effluents generated in fertilizer production.
12. Use according to claim 11, wherein NOxis removed from a gaseous effluent generated in the fertilizer production by means of oxidation by ozone of NO and N02present in the NOxto higher nitrogen oxides providing in a resultant gas mixture, and scrubbing the resultant gas mixture by means of a wet scrubber thereby removing the higher nitrogen oxides.
13. Use according to claim 11 or 12, wherein the fertilizer production is by acid digestion of phosphate ore.
14. Use according to any of claims 11 to 13, wherein ozone is used in a molar ratio of ozone over NOxin the gaseous effluent of 0.7 to 1.4.
15. Fertilizer production plant comprising: a reactor(1); a gas outlet (2) connected to the reactor (1); a wet scrubber (5) configured to receive an NOx-containing gaseous
effluent produced in the reactor (1); a connector (4), connecting the gas outlet (2) and the scrubber (5),
configured to transport the gaseous effluent;characterised in thatan ozone generator (3) is connected to the connector (4) or the wet scrubber (5) and is configured to inject ozone into the gaseous effluent.
16. Fertilizer production plant according to claim 15, wherein a gas analyser (14) is present in the gas outlet (2), the connector (4) or a final stack (6) connected to said wet scrubber (5), and is configured to analyse at least part of the composition of the gaseous effluent and control the ozone injection on the basis of the NOxconcentration measured.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO20150574A NO20150574A1 (en) | 2015-05-08 | 2015-05-08 | Reduction of nox emission during fertilizer production |
| PCT/EP2016/059892 WO2016180676A1 (en) | 2015-05-08 | 2016-05-03 | Reduction of nox emissions by effluent gases from fertilizer production with ozone injection and wet scrubbing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO20150574A NO20150574A1 (en) | 2015-05-08 | 2015-05-08 | Reduction of nox emission during fertilizer production |
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| NO20150574A1 true NO20150574A1 (en) | 2016-11-09 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0532207A1 (en) * | 1991-08-29 | 1993-03-17 | Cannon Boiler Works Inc. | A process for removing contaminants from exhaust gas |
| EP1040863A2 (en) * | 1999-03-15 | 2000-10-04 | Cannon Technology, Inc. | Process for removing NOx and SOx from exhaust gas |
-
2015
- 2015-05-08 NO NO20150574A patent/NO20150574A1/en not_active Application Discontinuation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0532207A1 (en) * | 1991-08-29 | 1993-03-17 | Cannon Boiler Works Inc. | A process for removing contaminants from exhaust gas |
| EP1040863A2 (en) * | 1999-03-15 | 2000-10-04 | Cannon Technology, Inc. | Process for removing NOx and SOx from exhaust gas |
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