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WO1986005712A1 - Procede et catalyseur de reduction de l'oxyde d'azote des gaz de fumee - Google Patents

Procede et catalyseur de reduction de l'oxyde d'azote des gaz de fumee Download PDF

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Publication number
WO1986005712A1
WO1986005712A1 PCT/FI1986/000034 FI8600034W WO8605712A1 WO 1986005712 A1 WO1986005712 A1 WO 1986005712A1 FI 8600034 W FI8600034 W FI 8600034W WO 8605712 A1 WO8605712 A1 WO 8605712A1
Authority
WO
WIPO (PCT)
Prior art keywords
catalyst
flue gases
flue
nitrogen oxides
particles
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/FI1986/000034
Other languages
English (en)
Inventor
Kari Saviharju
Keijo Jaanu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ekono Oy
Original Assignee
Ekono Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ekono Oy filed Critical Ekono Oy
Publication of WO1986005712A1 publication Critical patent/WO1986005712A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/85—Chromium, molybdenum or tungsten
    • B01J23/86—Chromium
    • B01J23/868—Chromium copper and chromium
    • 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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst

Definitions

  • the present invention relates to a process for lowering the concentration of nitrogen oxides in flue gases, and especially to a process in which the nitrogen oxides present in hot flue gases are reduced by means of ammonia or the unburnt constituents of the flue gases, in the presence of particles which catalyze the reduction of the oxides of nitrogen.
  • this invention relates to a catalyst intended for use in this process.
  • the catalyst cell system used in the technical applications is made up of small passages through which the flue gases flow and which are easily soiled, which results i a lowering of the effectiveness of the catalyst.
  • the catalys is soiled especially during the burning of solid fuels such as coal. Attempts have been made to eliminate this drawback by placing the removing device of nitrogen oxides at a point subsequent to the sulfur-removing device, but in such cases the temperature of the flue gas has been too low for the reactions.
  • the disadvantageous factors presented above can be decreased decisively and, furthermore, when the process is applied specifically to fluidized-bed burning, a simple structure can be achieved.
  • pellet catalysts are used in a solid bed, whereas pellet and cylinder catalysts are used as a moving bed so that the incoming flue-gas flow can pass through the pellet bed.
  • pellet catalysts are not suitable for a heavy load of dust, since the dust (fly ash) will deposit on the surface of the catalysts, whereupon the activity of the catalyst will decrease and, when the operating time increases, the loss of weight will become immoderately large.
  • Solid-bed catalysts made on a ceramic base have proved to be successful in removing nitrogen oxides from flue gases derived from the burning of heavy fuel oil, whereas, if the fuel is coal, a reduction degree of only 60 % has been achieved with these catalysts.
  • the object of the present invention is thus also to provide an improved catalyst for reducing the nitrogen oxides present in hot flue gases, by using ammonia and/or the unburnt constituents of the flue gases, the catalyst retaining its activity also in conditions in which they are subject to a high degree of soiling.
  • an effective contact between the catalyst and the gases is obtained by mixing, with the hot flow of flue gases, catalys particles which are so small, preferably of a particle size of approximately 20-200 m, that they form together with the flue gases a suspension flow in which the catalyst particles additionally, owing to a turbulent flow, continually,_impinge against both one another and the conduit walls, so that the surfaces of the catalyst particles are continuously cleaned, whereby the activity of the catalyst remains at an effective level.
  • the catalyst particles can be separated from the gas flow after the reduction of the nitrogen oxides and be returned to the beginning of the hot flue-gas flow.
  • the catalyst particles are small, they are, nevertheless, preferably substantially larger or heavier tha the fly-ash particles possibly present in the flue-gas flow, so that the catalyst particles can be removed selectively from the flue-gas flow and the fly ash present in it after the reduction of the nitrogen oxides.
  • the particles catalyzing the reduction of nitrogen oxides ar preferably mixed with a flue-gas flow having a temperature o at maximum 1000 °C, for example approximately 300-600 °C.
  • the catalyst according to the invention thus differs from th previously known catalysts in that it flows along with the flue-gas flow, for example, as a part of the solids cycle of the fluidized-bed reactor.
  • the actual reduction takes place at a temperature of approximately 350-450 °C.
  • the catalyst is regenerated and the reaction surface remains active. It is also possible to circulate the catalyst as an actual fluidized bed in which reactivation takes place.
  • the catalyst can be prepared on a i ⁇ 2 base and be impregnated with the following elements: W, V, Ca, Mo, Fe, Cr, and/or Cu.
  • the catalyst is prepared by mixing Ti ⁇ 2 and O3 with each other at a ratio of 3 to 1, at a temperature of 20-100 °C.
  • this powder mixture there are added nitrates of the above-mentioned elements in an aqueous solution, to which saltpeter acid approximately 5 % has been added.
  • the mixture is heated at 20-100 °C, until it attains a high viscosity.
  • the catalyst mixture is dried at a temperature of 100-150 °C for 24-48 h.
  • the catalyst particles are screened to form fractions having a diameter of approximately 200 ⁇ m.
  • composition of the catalyst is preferably as follows:
  • the catalyst prepared in the above-mentioned manner proved to be very effective in treating nitrogen-oxide-containing flue gases by means of ammonia, by using the apparatus depicted in the accompanying drawings, in which
  • Figure 1 depicts a cross-sectional side view of one apparatus for carrying out the process according to the present invention
  • FIG. 2 depicts, also as a cross-sectional side view, an alternative apparatus for carrying out the process according to the present invention.
  • the nitrogen-oxide-containing hot flue-gas flow is indicated by reference numeral 1.
  • Finely-divided selective catalyst 8 according to the invention is fed into this flue-gas flow by means of feeding device 9 and, at a point immediately thereafter, in order to reduce the nitrogen oxides present in the flue gases, ammonia 10 by means of feeding device 11.
  • the mutual order of the points at which the catalyst 8 and the ammonia 10 are fed in does not affect the working of the process according to the invention.
  • the catalyst 8 and the ammonia 10 can also be fed into the flue gases 1 by means of a common feeding device resembling a burner.
  • the ammonia 8 can be left out completel or partially, if the flue gases 1 are derived from a burning which has been regulated so that the gases contain unburnt gases, such as hydrocarbons or carbon monoxides, in an amount sufficient for reducing the nitrogen oxides present in the flue gases.
  • the temperature of the flue gases must be below 1000 oC » preferably below 500 °C, in order for the course of the reaction to be maximally advantageous.
  • the coarse fraction of the catalyst is separated i the reactor funnel 3, from where it is blown or conveyed in some other manner back to the feeding-in point 9.
  • the finer fraction of the catalyst is separated from the flue gases either in a mechanical separator or in an electro-filter 4, in order to ' be returned as flow 7 to the feeding-in point 9.
  • the separator 4 has been dimensioned so as to separate mainl catalysts but to allow fine fly ash to pass through.
  • the particle size of the catalyst should be substantially larger than that of the fly ash, for example, more than 30 m.
  • the particle size of the catalyst must, however, be so small that it flows along with the flue gases 1, forming a suspension with it. It has been observed in practice that a particle size under 200 ⁇ m is sufficient for this purpose.
  • the process according to the invention can be applied to all types of reactors and furnaces, both vertical and horizontal structures, although the vertical structure has certain advantages in terms of the circulation of the catalyst.
  • the process according to the invention can also be applied to a fluidized-bed reactor operating according to the circulating-bed principle, depicted in Figure 2, in which most of the catalyst 8 circulates from a furnace 16 via a cyclone 12 and a bed-material return 14 back to the furnace 16. Part of the bed material can be removed as an underflow 13 from the bottom of the furnace 16.
  • the flue gases which contain nitrogen oxide are directed as a flow 1 into the lower part of the furnace 16, from where they flow through the bed to the upper part of the furnace 16, where ammonia 10 is injected into them by means of a nozzle 11.
  • the separating device 4 can be, for example, a mechanical separator such as a cyclone, or an electro- or fiber filter.
  • the separator 4 can be designed so as to separate primarily catalyst dust and to let fly ash pass through, whereby an unreasonable increase in the amount of dust in the cycle is avoided.
  • a separator 4 can be, for example, a cyclone of the type used as a coarse separator in connection with so-called bubbling fluidized-bed reactors, and from which separator the unburnt fuel is returned to the furnace.
  • the ammonia 10 required for the reduction of the nitrogen oxides of the flue gases 1 is fed into the furnace 16 throug a nozzle 11 fitted in its upper part, or alternatively into the entrance conduit of the cyclone 12, in order to obtain maximal mixing between the ammonia and the flue gases.
  • the nozzle 11 can also be fitted in the cyclone 12 or at a point subsequent to it, but in that case the mixing effect of the cyclone 12 cannot be exploited in the best possible manner.
  • ammonia it is possible to use for the reduction unburnt gases, which are obtained by carrying out incompletely the burning from which the flue gases are derived.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

Procédé permettant d'abaisser la concentration d'oxyde d'azote dans des gaz de fumée chauds (1), en utilisant de l'ammoniac (10) en présence de particules (8) qui catalysent la réduction des oxydes d'azote. De manière à obtenir le meilleur contact entre les gaz (1) et le catalyseur (8), de petites particules de catalyse (8) sont mélangées avec le flux de gaz de fumée chauds, les particules étant si petites qu'elles forment avec les gaz de fumée un flux de suspension, d'où les particules de catalyse sont séparées (3, 4) après la réduction de l'oxyde d'azote et retournent (6, 7) au point de départ du flux de gaz de fumée chauds (1). La présente invention se rapporte également au catalyseur utilisé dans ledit procédé.
PCT/FI1986/000034 1985-04-04 1986-04-01 Procede et catalyseur de reduction de l'oxyde d'azote des gaz de fumee Ceased WO1986005712A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI851382 1985-04-04
FI851382A FI851382A0 (fi) 1985-04-04 1985-04-04 Foerfarande och katalysator foer reduktion av kvaeveoxidhalten i roekgaser.

Publications (1)

Publication Number Publication Date
WO1986005712A1 true WO1986005712A1 (fr) 1986-10-09

Family

ID=8520640

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1986/000034 Ceased WO1986005712A1 (fr) 1985-04-04 1986-04-01 Procede et catalyseur de reduction de l'oxyde d'azote des gaz de fumee

Country Status (3)

Country Link
EP (1) EP0216885A1 (fr)
FI (1) FI851382A0 (fr)
WO (1) WO1986005712A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0266807A3 (en) * 1986-10-02 1988-11-30 Metallgesellschaft Ag Method of catalytically reducing nitrogen oxide
EP0385958A3 (fr) * 1989-02-27 1990-11-28 Eka Nobel Aktiebolag Catalyseur pour la réduction des oxydes d'azote, procédé pour sa préparation et son utilisation
EP0274148B1 (fr) * 1986-12-06 1993-11-18 Metallgesellschaft Ag Procédé de réduction catalytique du monoxyde d'azote contenu dans un gaz
DE19612241A1 (de) * 1996-03-27 1997-10-02 Abb Patent Gmbh Verfahren und Vorrichtung zur Entsorgung von verbrauchten Katalysatoren für die Abscheidung von Schadstoffen, insbesondere von Stickoxiden, aus Rauchgas und deren Entlüftung
DE19612240A1 (de) * 1996-03-27 1997-10-02 Abb Patent Gmbh Verfahren und Vorrichtung zur Abscheidung von Schadstoffen, insbesondere von Stickoxiden, aus Rauchgas
WO1998026854A3 (fr) * 1996-12-18 1998-07-30 Metallgesellschaft Ag Procede de decomposition catalytique d'oxydes d'azote
WO2006032288A1 (fr) * 2004-09-22 2006-03-30 Lurgi Lentjes Ag Dispositif de purification de gaz de fumee

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1542314B2 (de) * 1965-01-30 1977-04-07 Mitsubishi Jukogyo KJC., Tokio Verfahren und vorrichtung zur entfernung von schwefeloxiden aus abgasen
US4085193A (en) * 1973-12-12 1978-04-18 Mitsubishi Petrochemical Co. Ltd. Catalytic process for reducing nitrogen oxides to nitrogen
GB1549376A (en) * 1975-05-16 1979-08-08 Nippon Kokan Kk Method of removing nitrogen oxides from an exhaust gas
SE422890B (sv) * 1975-05-06 1982-04-05 Hoelter H Sett for gasrening samt anordning herfor
US4466947A (en) * 1980-05-31 1984-08-21 Mitsubishi Petrochemical Co. Ltd. Denitration catalyst and denitrating method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1542314B2 (de) * 1965-01-30 1977-04-07 Mitsubishi Jukogyo KJC., Tokio Verfahren und vorrichtung zur entfernung von schwefeloxiden aus abgasen
US4085193A (en) * 1973-12-12 1978-04-18 Mitsubishi Petrochemical Co. Ltd. Catalytic process for reducing nitrogen oxides to nitrogen
SE422890B (sv) * 1975-05-06 1982-04-05 Hoelter H Sett for gasrening samt anordning herfor
GB1549376A (en) * 1975-05-16 1979-08-08 Nippon Kokan Kk Method of removing nitrogen oxides from an exhaust gas
US4466947A (en) * 1980-05-31 1984-08-21 Mitsubishi Petrochemical Co. Ltd. Denitration catalyst and denitrating method

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Chemical ABstract Vol 89 (1978), abstract NO 94 443J *
Chemical Abstracts Vol 87 (1977), abstract NO 28 359u *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0266807A3 (en) * 1986-10-02 1988-11-30 Metallgesellschaft Ag Method of catalytically reducing nitrogen oxide
EP0274148B1 (fr) * 1986-12-06 1993-11-18 Metallgesellschaft Ag Procédé de réduction catalytique du monoxyde d'azote contenu dans un gaz
EP0385958A3 (fr) * 1989-02-27 1990-11-28 Eka Nobel Aktiebolag Catalyseur pour la réduction des oxydes d'azote, procédé pour sa préparation et son utilisation
US5064792A (en) * 1989-02-27 1991-11-12 Eka Nobel Ab Catalyst for the reduction of nitrogen oxides, a method for its preparation and the use thereof
DE19612241A1 (de) * 1996-03-27 1997-10-02 Abb Patent Gmbh Verfahren und Vorrichtung zur Entsorgung von verbrauchten Katalysatoren für die Abscheidung von Schadstoffen, insbesondere von Stickoxiden, aus Rauchgas und deren Entlüftung
DE19612240A1 (de) * 1996-03-27 1997-10-02 Abb Patent Gmbh Verfahren und Vorrichtung zur Abscheidung von Schadstoffen, insbesondere von Stickoxiden, aus Rauchgas
WO1998026854A3 (fr) * 1996-12-18 1998-07-30 Metallgesellschaft Ag Procede de decomposition catalytique d'oxydes d'azote
WO2006032288A1 (fr) * 2004-09-22 2006-03-30 Lurgi Lentjes Ag Dispositif de purification de gaz de fumee

Also Published As

Publication number Publication date
EP0216885A1 (fr) 1987-04-08
FI851382A0 (fi) 1985-04-04

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