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WO2012146462A1 - Method for reducing the emission of nitrogen oxides in the exhaust gas of a furnace during the thermal treatment of materials and furnace operated according to said method - Google Patents

Method for reducing the emission of nitrogen oxides in the exhaust gas of a furnace during the thermal treatment of materials and furnace operated according to said method Download PDF

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Publication number
WO2012146462A1
WO2012146462A1 PCT/EP2012/056022 EP2012056022W WO2012146462A1 WO 2012146462 A1 WO2012146462 A1 WO 2012146462A1 EP 2012056022 W EP2012056022 W EP 2012056022W WO 2012146462 A1 WO2012146462 A1 WO 2012146462A1
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WO
WIPO (PCT)
Prior art keywords
furnace
exhaust gas
agent
content
nitrogen oxides
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/EP2012/056022
Other languages
German (de)
French (fr)
Inventor
Victor Yuardi RISONARTA
Markus Abel
Michel HEIN
Alexander Müller
Mehmet Fatih GÖKCE
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.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
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Filing date
Publication date
Application filed by Siemens AG, Siemens Corp filed Critical Siemens AG
Priority to RU2013152604/05A priority Critical patent/RU2013152604A/en
Priority to CN201280019785.6A priority patent/CN103702743A/en
Publication of WO2012146462A1 publication Critical patent/WO2012146462A1/en
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
    • 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
    • B01D53/30—Controlling by gas-analysis apparatus
    • 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
    • B01D53/565—Nitrogen oxides by treating the gases with solids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/202—Hydrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/204—Carbon monoxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/208—Hydrocarbons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0233—Other waste gases from cement factories
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/025—Other waste gases from metallurgy plants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

Definitions

  • the invention relates to a method for reducing the emission of nitrogen oxides in the exhaust gas of a furnace during the thermal treatment of materials in at least indirect presence of oxygen and nitrogen, in particular when melting iron-containing starting materials in an electric arc furnace.
  • the invention also relates to a furnace operated by this method.
  • thermal treatment is at least indirectly, ie at least in the exhaust oxygen and nitrogen at high temperatures anwe ⁇ send, so that thermal nitrogen oxides NO x can arise and get into the environment.
  • These nitrogen oxides NO x is environmentally harmful and toxic gases that both un ⁇ indirectly endanger the health and contribute, among other things as greenhouse gases to global warming, so the TERMS ⁇ on nitrogen oxides that arise in industrial processes, for reasons of Environmental protection should be avoided as much as possible.
  • the invention is therefore based on the object, a method for reducing the emission of nitrogen oxides in a Ab- to provide gas to be thermally treated at the factory ⁇ materials in at least indirect presence of oxygen and nitrogen in a furnace at high temperature is produced during a process.
  • the invention is based on the object of specifying a furnace operated by this method.
  • the stated object is achieved by a method having the features of claim 1.
  • the exhaust gas is at least one reducing agent and / or at least one supplied with oxygen in a competing reaction agent.
  • the metering of such agent which may be a substance or a mixture of different substances, can thus the emission of nitrogen oxides significantly reduced the ⁇ .
  • the method is particularly suitable for the treatment of exhaust gases that arise during the melting of metal scrap in an electric arc furnace.
  • the method is also applicable to the exhaust gas treatment in other processes in which metallic or non-metallic materials are subjected to a heat treatment at temperatures above 500 ° C.
  • These are for example stoves, which come in Stahlerzeu ⁇ supply is used, for example, LD converters, ladle furnaces, dies, reheating furnaces or blast furnaces.
  • Equally applicable is the method for the treatment of exhaust gases that arise in sintering furnaces, rolling mills in the reheating of slabs or in so-called bonnet furnaces in which, for example, ceramic materials are produced arise.
  • the process is equally applicable in the cement industry, in coal-fired power plants, chemical plants and in the oil and gas industry.
  • the agent can additionally be introduced directly into a furnace vessel of the furnace.
  • At least one of C, Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu, Zn and Pb is preferably added either in pure form or in the form of a compound having another element of this group ,
  • hydrogen H 2 , carbon monoxide CO, methane CH 4 or urea CO (NH) 2 or a mixture of these gases can also be supplied.
  • These elements and gases act as a reducing agent for nitrogen monoxide NO and nitrous oxide N 2 O, since the free Gibbs Ener gy ⁇ the reduction reaction of nitrogen monoxide NO and
  • Nitrous oxide N 2 O with one of these elements or gases in the particularly relevant temperature range between 1000 and 2000 ° C is negative, this reduction reaction takes place even in the absence of catalysts.
  • the free Gibbs energies g (Gibbs energy or free enthalpy) in kJ / mol N o or kJ / mol N 2 o for selected reduction reactions against the temperature T are shown by way of example in FIGS. 1 and 2.
  • Oxygen oxidizes and in this way displaces the chemical balance to the disadvantage of the formation of nitrogen oxides NO x . Also for the competition reactions with oxygen, the free Gibbs energies g are negative in the interesting temperature range between 1000 and 2000 ° C., as can be seen from FIG. 3.
  • the reactions are also accelerated catalytically, if the exhaust gas in a preferred embodiment additionally a catalytically active solid, especially dust, sand,
  • Potassium K, sodium Na, iron Fe, calcium Ca or calcium monoxide CaO be supplied.
  • the content of nitrogen oxides in the exhaust gas is measured and the agent is added as a function of this content of the exhaust gas in the flow direction of the exhaust gas, in particular after the sampling point.
  • carbon monoxide CO, methane CH 4 or urea CO (NH) 2 can be measured and the agent is seen as a function of this content to the exhaust gas in the flow direction of the exhaust gas in particular according to the sampling point insbeson ⁇ dere metered then, if their content in the exhaust gas below predetermined values or the content of nitrogen oxides is greater than a predetermined value for each nitric oxide.
  • the supply of the agent dosage occurs in particular only if also the temperature exceeds a predetermined value, preferably 500 ° C to 1000 ° C ⁇ particular because then the reaction kinetics are accelerated and the reactions with a particularly high Ge ⁇ speed take place.
  • a predetermined value preferably 500 ° C to 1000 ° C ⁇ particular because then the reaction kinetics are accelerated and the reactions with a particularly high Ge ⁇ speed take place.
  • the object is achieved according to the invention with a furnace having the features of claim 10.
  • Advantageous embodiments of the furnace are given in the subordinate claims subordinate to this claim.
  • the advantages of the related to the oven claims entspre ⁇ chen thereby mutatis mutandis the advantages indicated for the respective corresponding method claims.
  • FIG. 1 and 2 in each case a diagram in which the free Gibbss che energy g is plotted for reactions according to the invention used agents with nitrogen oxides against the temperature T
  • FIG. 3 is a diagram in which the free Gibbs energy is applied Ener ⁇ g for reactions of the agents used in this invention with oxygen against the temperature T,
  • Fig. 4 is a schematic representation of a furnace ge ⁇ according to the invention.
  • a furnace comprises the thermal treatment of materials, which in the example is an electric arc furnace, a furnace vessel 2, in which ferrous output ⁇ material, for example steel scrap, DRI or HBI by ei ⁇ NEN between electrodes 4 and the Scrap steel burning arc is melted, with a slag layer 8 forms above the melt 6.
  • ferrous output ⁇ material for example steel scrap, DRI or HBI by ei ⁇ NEN between electrodes 4 and the Scrap steel burning arc is melted, with a slag layer 8 forms above the melt 6.
  • Additives for the melting process for example oxygen or carbon 0 C zugege ⁇ ben.
  • the resulting during melting exhaust gas OG is discharged via a connected to the furnace vessel 2 exhaust pipe 12 and performed for dedusting to a cyclone not shown in the figure.
  • the exhaust pipe 12 includes a nozzle 14, which opens into a main line 16 leaving an annular gap 15. Through the annular gap 15 ambient air A is sucked in, which leads to an afterburning of the
  • a sampling system 18 is connected to the at least one sampling point from the exhaust gas OG a gas sample SG removed and an Analy ⁇ se noticed 20 is supplied in the gas sample SG on the content of nitrogen oxides NO x and / or hydrogen H 2 , carbon monoxide CO, methane CH 4 or urea CO (NH) 2 is analyzed.
  • the temperature T of the exhaust gas OG at the location of the sampling is measured with a temperature measuring device 22.
  • the measured values M determined by the analysis device 20 and the temperature T determined by the temperature measuring device 22 are forwarded to a control device 24 in which, depending on this measured value M and this temperature T, a control signal S1 for a metering device 26 is generated which is supplied via a supply line 28 is connected to the exhaust gas line 12. With the feed line 28 opening into the exhaust gas line 12, the agent O reducing or reacting in a competing reaction is fed to the exhaust gas OG.
  • the exhaust gas OG amount depends on the concentration existing at the sampling point in the From ⁇ gas OG abovementioned substances.
  • a the metered addition of the reduzie- rend acting or reacting in a competing reaction agent R is effecting control signal Sl only then ⁇ evidence when this temperature T exceeds a predetermined value, in particular 500 ° C, and in addition the NOx content prescribed in the exhaust gas OG Values exceeds or the content of methane CH 4 or carbon monoxide CO or hydrogen H 2 or urea CO (NH) 2 in the exhaust gas OG predetermined values undershoot ⁇ or not exceeded.
  • a Zudo ⁇ tion of the agent R does not take place in this procedure, if the temperature T falls below this predetermined value.
  • the sampling location is in Strö ⁇ direction of flow of the exhaust gas OG seen the point in the supply line opens into the exhaust pipe 12 28th Prin- Piell, a reverse arrangement is conceivable in which the supply of the agents R is controlled so then that in ⁇ play, the content of nitrogen oxides NO x in the area of the sampling site is minimal.
  • an agent R can also be supplied via a further supply line 30 opening into the furnace vessel 2 be introduced directly into the furnace vessel 2.
  • a control signal S2 is generated by the controller 24 connected with the one on the other supply line 30 to the furnace vessel 2 further metering device 32 is ⁇ is controlled.
  • reduzie ⁇ rend acting or reacting in a competing reaction agent R is preferably only supplied to the furnace vessel, in this case, when the temperature T exceeds a predetermined value in the exhaust gas OG, and additionally exceed the NO x content in the exhaust gas OG specified differently bene values or the content of methane CH 4 or carbon monoxide CO or hydrogen H2 or urea CO (NH) 2 in the exhaust gas OG falls below predetermined values.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Catalysts (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

The invention relates to a method for reducing the emission of nitrogen oxides in the exhaust gas (OG) of a furnace during the thermal treatment of materials in at least the indirect presence of oxygen and nitrogen, in particular when melting ferrous starting materials in an arc furnace, and to a furnace operated according to said method, wherein an agent (A) acting in a reducing manner and/or reacting with oxygen in a competing reaction is supplied to the exhaust gas (OG).

Description

Beschreibung description

Verfahren zum Vermindern der Emission von Stickoxiden im Abgas eines Ofens bei der thermischen Behandlung von Werkstoffen und nach diesem Verfahren betriebener Ofen A method for reducing the emission of nitrogen oxides in the exhaust gas of a furnace in the thermal treatment of materials and furnace operated by this method

Die Erfindung bezieht sich auf ein Verfahren zum Vermindern der Emission von Stickoxiden im Abgas eines Ofens bei der thermischen Behandlung von Werkstoffen in zumindest mittelbarer Anwesenheit von Sauerstoff und Stickstoff, insbesondere beim Schmelzen von eisenhaltigen Ausgangsstoffen in einem Lichtbogenofen. Die Erfindung bezieht sich außerdem auf einen mit diesem Verfahren betriebenen Ofen. The invention relates to a method for reducing the emission of nitrogen oxides in the exhaust gas of a furnace during the thermal treatment of materials in at least indirect presence of oxygen and nitrogen, in particular when melting iron-containing starting materials in an electric arc furnace. The invention also relates to a furnace operated by this method.

Bei der thermischen Behandlung von Werkstoffen in zumindest mittelbarer Anwesenheit von Sauerstoff und Stickstoff, bei¬ spielsweise beim Schmelzen von Stahlschrott, DRI (Direct Re- duced I_ron) oder HBI (Hot Briquetted I_ron) in einem Lichtbo¬ genofen, kommt es bei Temperaturen über 1000°C zur Bildung von Stickoxiden NOx. Die Entstehung solcher sogenannter thermischer Stickoxide NOx kann dabei sowohl unmittelbar im Ofengefäß selbst als auch im Abgas erfolgen, wenn den aus dem Ofengefäß abgeleiteten Abgasen bei hoher Temperatur Umgebungsluft beigemischt wird, wie es beispielsweise bei Licht¬ bogenöfen der Fall ist. Mit anderen Worten: Bei der thermischen Behandlung ist zumindest mittelbar, d.h. zumindest im Abgas Sauerstoff und Stickstoff bei hohen Temperaturen anwe¬ send, so dass thermische Stickoxide NOx entstehen und in die Umgebung gelangen können. Bei diesen Stickoxiden NOx handelt es sich um umweltschädliche und giftige Gase, die sowohl un¬ mittelbar die Gesundheit gefährden als auch unter anderem als Treibhausgase zur Erderwärmung beitragen, so dass die Emissi¬ on von Stickoxiden, die bei technischen Prozessen entstehen, aus Gründen des Umweltschutzes weitestgehend vermieden werden sollte . In the thermal treatment of materials in at least indirect presence of oxygen and nitrogen at ¬ play in the melting of steel scrap, DRI (Direct re- duced I_ron) or HBI (Hot Briquetted I_ron) genofen ¬ in a Lichtbo, occurs at temperatures above 1000 ° C for the formation of nitrogen oxides NO x . The emergence of such so-called thermal nitrogen oxides NO x it can be done either directly in the furnace vessel itself and in the exhaust gas when the exhaust gases derived from the furnace vessel is mixed at high temperature ambient air, as is the case for example with light ¬ arc furnaces. In other words: In the thermal treatment is at least indirectly, ie at least in the exhaust oxygen and nitrogen at high temperatures anwe ¬ send, so that thermal nitrogen oxides NO x can arise and get into the environment. These nitrogen oxides NO x is environmentally harmful and toxic gases that both un ¬ indirectly endanger the health and contribute, among other things as greenhouse gases to global warming, so the TERMS ¬ on nitrogen oxides that arise in industrial processes, for reasons of Environmental protection should be avoided as much as possible.

Der Erfindung liegt daher die Aufgabe zu Grunde, ein Verfahren zum Vermindern der Emission von Stickoxiden in einem Ab- gas anzugeben, das bei einem Prozess entsteht, bei dem Werk¬ stoffe in zumindest mittelbarer Anwesenheit von Sauerstoff und Stickstoff in einem Ofen bei hoher Temperatur thermisch behandelt werden. Außerdem liegt der Erfindung die Aufgabe zu Grunde einen mit diesem Verfahren betriebenen Ofen anzugeben. The invention is therefore based on the object, a method for reducing the emission of nitrogen oxides in a Ab- to provide gas to be thermally treated at the factory ¬ materials in at least indirect presence of oxygen and nitrogen in a furnace at high temperature is produced during a process. In addition, the invention is based on the object of specifying a furnace operated by this method.

Hinsichtlich des Verfahrens wird die genannte Aufgabe gelöst mit einem Verfahren mit den Merkmalen des Patentanspruches 1. Bei diesem Verfahren werden dem Abgas zumindest ein reduzierend wirkendes und/oder zumindest ein mit Sauerstoff in einer Konkurrenzreaktion reagierendes Agens zugeführt. In beiden Fällen werden im Abgas mitgeführte oder im Abgas bei hohen Temperaturen unmittelbar hinter dem Ofen durch Zufuhr von Luft oder Sauerstoff entstehende Stickoxide entweder redu¬ ziert oder es wird durch den Abbau von Sauerstoff in der Kon¬ kurrenzreaktion das chemische Gleichgewicht zu Ungunsten der Entstehung von Stickoxiden verschoben. Durch das Zudosieren eines derartigen Agens, bei dem es sich um einen Stoff oder um ein Gemisch aus verschiedenen Stoffen handeln kann, kann somit die Emission von Stickoxiden signifikant reduziert wer¬ den . With regard to the method, the stated object is achieved by a method having the features of claim 1. In this method, the exhaust gas is at least one reducing agent and / or at least one supplied with oxygen in a competing reaction agent. In both cases, in the exhaust gas or carried in the exhaust gas at high temperatures immediately after the furnace through the supply of air or oxygen resulting nitrogen oxides either redu ¬ sheet or it is determined by the reduction of oxygen in the Kon ¬ kurrenzreaktion the chemical equilibrium to the detriment of the formation of Nitrogen oxides shifted. Through the metering of such agent, which may be a substance or a mixture of different substances, can thus the emission of nitrogen oxides significantly reduced the ¬.

Das Verfahren eignet sich insbesondere für die Behandlung von Abgasen, die beim Einschmelzen von Metallschrott in einem Lichtbogenofen entstehen. Grundsätzlich ist das Verfahren auch für die Abgasbehandlung bei anderen Prozessen anwendbar, bei denen metallische oder nichtmetallische Werkstoffe einer Wärmebehandlung bei Temperaturen über 500 °C unterzogen werden. Dies sind beispielsweise Öfen, die bei der Stahlerzeu¬ gung zum Einsatz gelangen, beispielsweise LD-Konverter, Pfannenöfen, Kokillen, Reheating-Öfen oder Hochöfen. Ebenso anwendbar ist das Verfahren für die Behandlung von Abgasen, die in Sinteröfen, in Walzwerken beim Wiedererwärmen von Brammen entstehen oder in sogenannten Haubenöfen, in denen beispielsweise keramische Werkstoffe erzeugt werden, entstehen. Ebenso anwendbar ist das Verfahren in der Zementindustrie, in Kohle- kraftwerken, Chemieanlagen und in der Öl- und Gasindustrie. Ergänzend hierzu kann das Agens auch zusätzlich direkt in ein Ofengefäß des Ofens eingeleitet werden. The method is particularly suitable for the treatment of exhaust gases that arise during the melting of metal scrap in an electric arc furnace. Basically, the method is also applicable to the exhaust gas treatment in other processes in which metallic or non-metallic materials are subjected to a heat treatment at temperatures above 500 ° C. These are for example stoves, which come in Stahlerzeu ¬ supply is used, for example, LD converters, ladle furnaces, dies, reheating furnaces or blast furnaces. Equally applicable is the method for the treatment of exhaust gases that arise in sintering furnaces, rolling mills in the reheating of slabs or in so-called bonnet furnaces in which, for example, ceramic materials are produced arise. The process is equally applicable in the cement industry, in coal-fired power plants, chemical plants and in the oil and gas industry. In addition to this, the agent can additionally be introduced directly into a furnace vessel of the furnace.

Als Agens wird vorzugsweise wenigstens ein Element aus der Gruppe C, Na, Mg, AI, Si, Ca, Ti, Cr, Mn, Ni, Cu, Zn und Pb entweder in Reinform oder in Form einer Verbindung mit einem anderen Element dieser Gruppe zugeführt. As the agent, at least one of C, Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu, Zn and Pb is preferably added either in pure form or in the form of a compound having another element of this group ,

Alternativ oder ergänzend hierzu können auch Wasserstoff H2, Kohlenmonoxid CO, Methan CH4 oder Harnstoff CO(NH)2 oder ein Gemisch aus diesen Gasen zugeführt werden. Diese Elemente bzw. Gase wirken als Reduktionsmittel für Stickstoffmonoxid NO und Distickstoffmonoxid N2O, da die freie Gibbssche Ener¬ gie der Reduktionsreaktion von Stickstoffmonoxid NO und Alternatively or additionally, hydrogen H 2 , carbon monoxide CO, methane CH 4 or urea CO (NH) 2 or a mixture of these gases can also be supplied. These elements and gases act as a reducing agent for nitrogen monoxide NO and nitrous oxide N 2 O, since the free Gibbs Ener gy ¬ the reduction reaction of nitrogen monoxide NO and

Distickstoffmonoxid N2O mit einem dieser Elemente bzw. Gase im besonders relevanten Temperaturbereich zwischen 1000 und 2000°C negativ ist, wobei diese Reduktionsreaktion auch in Abwesenheit von Katalysatoren stattfindet. In Fig. 1 und 2 sind exemplarisch die freien Gibbschen Energien g (Gibbssche Energie oder freie Enthalpie) in kJ/molNo bzw. kJ/molN2o für ausgewählte Reduktionsreaktionen gegen die Temperatur T aufgetragen . Nitrous oxide N 2 O with one of these elements or gases in the particularly relevant temperature range between 1000 and 2000 ° C is negative, this reduction reaction takes place even in the absence of catalysts. The free Gibbs energies g (Gibbs energy or free enthalpy) in kJ / mol N o or kJ / mol N 2 o for selected reduction reactions against the temperature T are shown by way of example in FIGS. 1 and 2.

Darüber hinaus werden die Elemente C, Na, Mg, AI, Si, Ca, Ti, Cr, Mn, Ni, Cu, Zn und Pb in einer Konkurrenzreaktion mitIn addition, the elements C, Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu, Zn and Pb are in competition with

Sauerstoff oxidiert und verschieben auf diese Weise das che¬ mische Gleichgewicht zuungunsten der Bildung von Stickoxiden NOx. Auch für die Konkurrenzreaktionen mit Sauerstoff sind die freien Gibbsschen Energien g im interessanten Temperatur- bereich zwischen 1000 und 2000°C negativ, wie dies der Fig. 3 zu entnehmen ist. Oxygen oxidizes and in this way displaces the chemical balance to the disadvantage of the formation of nitrogen oxides NO x . Also for the competition reactions with oxygen, the free Gibbs energies g are negative in the interesting temperature range between 1000 and 2000 ° C., as can be seen from FIG. 3.

Die Reaktionen werden außerdem katalytisch beschleunigt, wenn dem Abgas in einer bevorzugten Ausgestaltung zusätzlich ein katalytisch wirksamer Feststoff, insbesondere Staub, Sand,The reactions are also accelerated catalytically, if the exhaust gas in a preferred embodiment additionally a catalytically active solid, especially dust, sand,

Kalium K, Natrium Na, Eisen Fe, Calcium Ca oder Calciummono- xid CaO zugeführt werden. In einer weiteren vorteilhaften Ausgestaltung der Erfindung wird der Gehalt von Stickoxiden im Abgas gemessen und das Agens wird in Abhängigkeit von diesem Gehalt dem Abgas in Strömungsrichtung des Abgases gesehen insbesondere nach der Probenentnahmestelle zudosiert. Potassium K, sodium Na, iron Fe, calcium Ca or calcium monoxide CaO be supplied. In a further advantageous embodiment of the invention, the content of nitrogen oxides in the exhaust gas is measured and the agent is added as a function of this content of the exhaust gas in the flow direction of the exhaust gas, in particular after the sampling point.

Alternativ oder ergänzend hierzu kann im Abgas auch der Gehalt an Wasserstoff H2, Kohlenmonoxid CO, Methan CH4 oder Harnstoff CO(NH)2 gemessen und das Agens wird in Abhängigkeit von diesem Gehalt dem Abgas in Strömungsrichtung des Abgases gesehen insbesondere nach der Probenentnahmestelle insbeson¬ dere dann zudosiert, wenn deren Gehalt im Abgas vorgegebene Werte unterschreitet oder der Gehalt an Stickoxiden größer als ein für jedes Stickoxid vorgegebener Wert ist. Alternatively or additionally, in the exhaust gas and the content of hydrogen H2, carbon monoxide CO, methane CH 4 or urea CO (NH) 2 can be measured and the agent is seen as a function of this content to the exhaust gas in the flow direction of the exhaust gas in particular according to the sampling point insbeson ¬ dere metered then, if their content in the exhaust gas below predetermined values or the content of nitrogen oxides is greater than a predetermined value for each nitric oxide.

In einer weiteren Ausgestaltung der Erfindung erfolgt die Zu- dosierung des Agens insbesondere nur dann, wenn außerdem die Temperatur einen vorgegebenen Wert, vorzugsweise 500°C, ins¬ besondere 1000°C überschreitet, da dann die Reaktionskinetik beschleunigt ist und die Reaktionen mit besonders hoher Ge¬ schwindigkeit stattfinden. In a further embodiment of the invention, the supply of the agent dosage occurs in particular only if also the temperature exceeds a predetermined value, preferably 500 ° C to 1000 ° C ¬ particular because then the reaction kinetics are accelerated and the reactions with a particularly high Ge ¬ speed take place.

Hinsichtlich des Ofens wird die Aufgabe gemäß der Erfindung gelöst mit einem Ofen mit den Merkmalen des Patentanspruches 10. Vorteilhafte Ausgestaltungen des Ofens sind in den diesem Patentanspruch nachgeordneten Unteransprüchen angegeben. Die Vorteile der auf den Ofen bezogenen Patentansprüche entspre¬ chen dabei sinngemäß den zu den jeweils entsprechenden Verfahrensansprüchen angegebenen Vorteilen. With regard to the furnace, the object is achieved according to the invention with a furnace having the features of claim 10. Advantageous embodiments of the furnace are given in the subordinate claims subordinate to this claim. The advantages of the related to the oven claims entspre ¬ chen thereby mutatis mutandis the advantages indicated for the respective corresponding method claims.

Zur weiteren Erläuterung der Erfindung wird auf die Figuren verwiesen. Es zeigen: For further explanation of the invention reference is made to the figures. Show it:

Fig. 1 und 2 jeweils ein Diagramm, in dem die freie Gibbss- che Energie g für Reaktionen erfindungsgemäß verwendeter Agenzien mit Stickoxiden gegen die Temperatur T aufgetragen ist, Fig. 3 ein Diagramm, in dem die freie Gibbssche Ener¬ gie g für Reaktionen der erfindungsgemäß verwendeten Agenzien mit Sauerstoff gegen die Temperatur T aufgetragen ist, 1 and 2 in each case a diagram in which the free Gibbss che energy g is plotted for reactions according to the invention used agents with nitrogen oxides against the temperature T, Fig. 3 is a diagram in which the free Gibbs energy is applied Ener ¬ g for reactions of the agents used in this invention with oxygen against the temperature T,

Fig. 4 eine schematische Darstellung eines Ofens ge¬ mäß der Erfindung. Fig. 4 is a schematic representation of a furnace ge ¬ according to the invention.

Gemäß Fig. 4 umfasst ein Ofen zur thermischen Behandlung von Werkstoffen, bei dem es sich im Beispiel um einen Lichtbogenofen handelt, ein Ofengefäß 2, in dem eisenhaltiges Ausgangs¬ material, beispielsweise Stahlschrott, DRI oder HBI durch ei¬ nen zwischen Elektroden 4 und dem Stahlschrott brennenden Lichtbogen aufgeschmolzen wird, wobei sich über der Schmelze 6 eine Schlackenschicht 8 bildet. Mit Hilfe von Lanzen 10 werden in das Ofengefäß 2 Zusatzstoffe für den Schmelzpro- zess, beispielsweise Sauerstoff 0 oder Kohlenstoff C zugege¬ ben . Das beim Einschmelzen entstehende Abgas OG wird über eine an das Ofengefäß 2 angeschlossene Abgasleitung 12 abgeführt und zur Entstaubung zu einem in der Figur nicht mehr dargestellten Zyklon geführt. Die Abgasleitung 12 umfasst einen Stutzen 14, der unter Belassung eines Ringspaltes 15 in eine Haupt- leitung 16 mündet. Durch den Ringspalt 15 wird Umgebungsluft A angesaugt, die zu einer Nachverbrennung der im Abgas OG mitgeführten Stoffe führt. According to Fig. 4, a furnace comprises the thermal treatment of materials, which in the example is an electric arc furnace, a furnace vessel 2, in which ferrous output ¬ material, for example steel scrap, DRI or HBI by ei ¬ NEN between electrodes 4 and the Scrap steel burning arc is melted, with a slag layer 8 forms above the melt 6. With the help of lances 10 are in the furnace vessel 2 Additives for the melting process, for example oxygen or carbon 0 C zugege ¬ ben. The resulting during melting exhaust gas OG is discharged via a connected to the furnace vessel 2 exhaust pipe 12 and performed for dedusting to a cyclone not shown in the figure. The exhaust pipe 12 includes a nozzle 14, which opens into a main line 16 leaving an annular gap 15. Through the annular gap 15 ambient air A is sucked in, which leads to an afterburning of the entrained in the exhaust gas OG substances.

Sowohl im Ofengefäß 2 selbst als auch in der Abgasleitung 12 entstehen durch die Anwesenheit von Stickstoff N und Sauer¬ stoff 0 bei hohen Temperaturen Stickoxide NOx, die ohne wei¬ tere stickoxidmindernde Maßnahmen in die Atmosphäre gelangen würden . An die Abgasleitung 12 ist ein Probenentnahmesystem 18 angeschlossen, mit dem an zumindest einer Probenentnahmestelle aus dem Abgas OG eine Gasprobe SG entnommen und einer Analy¬ seeinrichtung 20 zugeführt wird, in der die Gasprobe SG auf den Gehalt an Stickoxiden NOx und/oder Wasserstoff H2, Koh- lenmonoxid CO, Methan CH4 oder Harnstoff CO(NH)2 analysiert wird. Zusätzlich wird mit einer Temperaturmesseinrichtung 22 die Temperatur T des Abgases OG am Ort der Probenentnahme ge- messen. Die von der Analyseeinrichtung 20 ermittelten Messwerte M und die von der Temperaturmesseinrichtung 22 ermittelte Temperatur T werden an eine Steuereinrichtung 24 weitergeleitet, in der abhängig von diesem Messwert M und dieser Temperatur T ein Steuersignal Sl für eine Dosiereinrichtung 26 generiert wird, die über eine Zufuhrleitung 28 an die Ab- gasleitung 12 angeschlossen ist. Mit der in die Abgasleitung 12 mündenden Zufuhrleitung 28 wird dem Abgas OG reduzierend wirkendes oder in einer Konkurrenzreaktion reagierendes Agens R zugeführt. Both in the furnace vessel 2 itself and in the exhaust pipe 12 caused by the presence of nitrogen N and sour ¬ substance 0 at high temperatures nitrogen oxides NO x , which would reach the atmosphere without wei ¬ tere nitric oxide reducing measures. To the exhaust pipe 12, a sampling system 18 is connected to the at least one sampling point from the exhaust gas OG a gas sample SG removed and an Analy ¬ seeinrichtung 20 is supplied in the gas sample SG on the content of nitrogen oxides NO x and / or hydrogen H 2 , carbon monoxide CO, methane CH 4 or urea CO (NH) 2 is analyzed. In addition, the temperature T of the exhaust gas OG at the location of the sampling is measured with a temperature measuring device 22. The measured values M determined by the analysis device 20 and the temperature T determined by the temperature measuring device 22 are forwarded to a control device 24 in which, depending on this measured value M and this temperature T, a control signal S1 for a metering device 26 is generated which is supplied via a supply line 28 is connected to the exhaust gas line 12. With the feed line 28 opening into the exhaust gas line 12, the agent O reducing or reacting in a competing reaction is fed to the exhaust gas OG.

Die von der Dosiereinrichtung 26 pro Zeiteinheit dem Abgas OG zugeführte Menge hängt dabei von der Konzentration der im Ab¬ gas OG an der Probenentnahmestelle vorhandenen obengenannten Stoffe ab. Insbesondere wird ein die Zudosierung des reduzie- rend wirkenden oder in einer Konkurrenzreaktion reagierenden Agens R bewirkendes Steuersignal Sl ausschließlich dann er¬ zeugt, wenn diese Temperatur T einen vorgegebenen Wert, insbesondere 500°C überschreitet und zusätzlich der NOx-Gehalt im Abgas OG vorgegebene Werte überschreitet oder der Gehalt an Methan CH4 oder Kohlenmonoxid CO oder Wasserstoff H2 oder Harnstoff CO(NH)2 im Abgas OG vorgegebene Werte unterschrei¬ tet oder nicht überschreitet. Mit anderen Worten: Eine Zudo¬ sierung des Agens R erfolgt bei dieser Verfahrensführung nicht, wenn die Temperatur T diesen vorgegebenen Wert unter- schreitet. The power supplied by the metering device 26 per unit time, the exhaust gas OG amount depends on the concentration existing at the sampling point in the From ¬ gas OG abovementioned substances. In particular, a the metered addition of the reduzie- rend acting or reacting in a competing reaction agent R is effecting control signal Sl only then ¬ evidence when this temperature T exceeds a predetermined value, in particular 500 ° C, and in addition the NOx content prescribed in the exhaust gas OG Values exceeds or the content of methane CH 4 or carbon monoxide CO or hydrogen H 2 or urea CO (NH) 2 in the exhaust gas OG predetermined values undershoot ¬ or not exceeded. In other words: A Zudo ¬ tion of the agent R does not take place in this procedure, if the temperature T falls below this predetermined value.

Im Beispiel findet sich die Probenentnahmestelle in Strö¬ mungsrichtung des Abgases OG gesehen vor der Stelle, in der die Zufuhrleitung 28 in die Abgasleitung 12 mündet. Prinzi- piell ist auch eine umgekehrte Anordnung denkbar, bei der dann die Zufuhr der Agenzien R so gesteuert wird, dass bei¬ spielsweise der Gehalt an Stickoxiden NOx im Bereich der Probenentnahmestelle minimal ist. Zusätzlich zu der gemäß der vorliegenden Erfindung vorgesehenen Maßnahme, bei der dem Abgas OG ein reduzierend wirkendes und/oder ein mit Sauerstoff in einer Konkurrenzreaktion reagierendes Agens R zugeführt wird, kann ein solches Agens R über eine weitere, in das Ofengefäß 2 mündende Zufuhrleitung 30 auch direkt in das Ofengefäß 2 eingeleitet werden. Hierzu wird von der Steuereinrichtung 24 ein Steuersignal S2 erzeugt, mit der eine über die weitere Zufuhrleitung 30 an das Ofengefäß 2 angeschlossene weitere Dosiereinrichtung 32 ange¬ steuert wird. Insbesondere wird auch in diesem Fall reduzie¬ rend wirkendes oder in einer Konkurrenzreaktion reagierendes Agens R vorzugsweise nur dann dem Ofengefäß zugeleitet, wenn die Temperatur T im Abgas OG einen vorgegebenen Wert überschreitet und zusätzlich der NOx-Gehalt im Abgas OG vorgege¬ bene Werte überschreitet oder der Gehalt an Methan CH4 oder Kohlenmonoxid CO oder Wasserstoff H2 oder Harnstoff CO(NH)2 im Abgas OG vorgegebene Werte unterschreitet. In the example, the sampling location is in Strö ¬ direction of flow of the exhaust gas OG seen the point in the supply line opens into the exhaust pipe 12 28th Prin- Piell, a reverse arrangement is conceivable in which the supply of the agents R is controlled so then that in ¬ play, the content of nitrogen oxides NO x in the area of the sampling site is minimal. In addition to the measure provided according to the present invention in which the exhaust gas OG is supplied with a reducing agent and / or an agent R reacting with oxygen in a competing reaction, such an agent R can also be supplied via a further supply line 30 opening into the furnace vessel 2 be introduced directly into the furnace vessel 2. For this purpose, a control signal S2 is generated by the controller 24 connected with the one on the other supply line 30 to the furnace vessel 2 further metering device 32 is ¬ is controlled. In particular reduzie ¬ rend acting or reacting in a competing reaction agent R is preferably only supplied to the furnace vessel, in this case, when the temperature T exceeds a predetermined value in the exhaust gas OG, and additionally exceed the NO x content in the exhaust gas OG specified differently bene values or the content of methane CH 4 or carbon monoxide CO or hydrogen H2 or urea CO (NH) 2 in the exhaust gas OG falls below predetermined values.

Claims

Patentansprüche claims 1. Verfahren zum Vermindern der Emission von Stickoxiden im Abgas (OG) eines Ofens bei der thermischen Behandlung von Werkstoffen in zumindest mittelbarer Anwesenheit von Sauerstoff und Stickstoff, insbesondere beim Schmelzen von eisen¬ haltigen Ausgangsstoffen in einem Lichtbogenofen, bei dem dem Abgas (OG) zumindest ein reduzierend wirkendes und/oder zu¬ mindest ein mit Sauerstoff in einer Konkurrenzreaktion rea- gierendes Agens (R) zugeführt werden. 1. A method for reducing the emission of nitrogen oxides in the exhaust gas (OG) of a furnace for the thermal treatment of materials in at least indirect presence of oxygen and nitrogen, particularly when melting iron ¬ containing starting materials in an electric arc furnace, in which the exhaust gas (OG) at least one reducing action and / or a minimum ¬ REA with oxygen in a reaction competing directing agent (R) are fed. 2. Verfahren nach Anspruch 1, bei dem zusätzlich Agens (R) direkt in ein Ofengefäß (2) des Ofens eingeleitet wird. 2. The method of claim 1, wherein additionally agent (R) is introduced directly into a furnace vessel (2) of the furnace. 3. Verfahren nach Anspruch 1 oder 2, bei dem als Agens (R) wenigstens ein Element aus der Gruppe C, Na, Mg, AI, Si, Ca, Ti, Cr, Mn, Ni, Cu, Zn und Pb entweder in Reinform oder in Form einer Verbindung mit einem anderen Element dieser Gruppe zugeführt wird. 3. The method of claim 1 or 2, wherein as the agent (R) at least one element from the group C, Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu, Zn and Pb either in pure form or in the form of a compound with another element of this group. 4. Verfahren nach Anspruch 1, 2 oder 3, bei dem als Agens (R) wenigstens ein Gas aus der Gruppe Wasserstoff H2, Kohlenmono- xid CO, Methan CH4 oder Harnstoff CO(NH)2 zugeführt wird. 4. The method of claim 1, 2 or 3, wherein as the agent (R) at least one gas from the group hydrogen H 2 , carbon monoxide CO, methane CH 4 or urea CO (NH) 2 is supplied. 5. Verfahren nach einem der vorhergehenden Ansprüche, bei dem zusätzlich ein die Reduktionsreaktion oder die Konkurrenzreaktion beschleunigender katalytisch wirksamer Feststoff zugeführt wird. 5. The method according to any one of the preceding claims, wherein in addition a reducing reaction or the competition reaction accelerating catalytically active solid is supplied. 6. Verfahren nach einem der vorhergehenden Ansprüche, bei dem der Gehalt von Stickoxiden und/oder der Gehalt an Wasserstoff H2, Kohlenmonoxid CO, Methan CH4 oder Harnstoff CO(NH)2 im Ab¬ gas (OG) an zumindest einer Probenentnahmestelle gemessen und das Agens (R) in Abhängigkeit von diesem Gehalt dem Abgas (OG) zudosiert wird. 6. The method according to any one of the preceding claims, wherein the content of nitrogen oxides and / or the content of hydrogen H 2 , carbon monoxide CO, methane CH 4 or urea CO (NH) 2 in Ab ¬ gas (OG) measured at least one sampling point and the agent (R) is metered into the exhaust gas (OG) as a function of this content. 7. Verfahren nach Anspruch 6, bei dem das Agens (R) nur dann zudosiert wird, wenn der Gehalt von Stickoxiden und/oder der Gehalt an Wasserstoff H2, Kohlenmonoxid CO, Methan CH4 oder Harnstoff CO(NH)2 im Abgas (OG) einen vorgegebenen Wert Über¬ bzw, unterschreitet. 7. The method according to claim 6, wherein the agent (R) is added only if the content of nitrogen oxides and / or the Content of hydrogen H 2 , carbon monoxide CO, methane CH 4 or urea CO (NH) 2 in the exhaust gas (OG) exceeds or falls below a predetermined value. 8. Verfahren nach Anspruch 6 oder 7, bei dem die Temperatur (T) des Abgases (OG) am Ort der Probenentnahme gemessen wird und eine Zudosierung des Agens (R) ausschließlich dann erfolgt, wenn diese einen vorgegebenen Wert überschreitet. 8. The method of claim 6 or 7, wherein the temperature (T) of the exhaust gas (OG) is measured at the place of sampling and a metered addition of the agent (R) takes place only when it exceeds a predetermined value. 9. Verfahren nach einem der Ansprüche 6 bis 8, bei dem die Zudosierung in Strömungsrichtung des Abgases (OG) gesehen nach der Probenentnahmestelle erfolgt. 9. The method according to any one of claims 6 to 8, wherein the metered addition takes place in the flow direction of the exhaust gas (OG) after the sampling point. 10. Ofen zur thermischen Behandlung von Werkstoffen, insbe- sondere Lichtbogenofen, mit einer an ein Ofengefäß (2) angeschlossenen Abgasleitung (12) und einer in die Abgasleitung (12) mündenden Zufuhrleitung (28) zum Zuführen zumindest eines reduzierend wirkenden und/oder zumindest eines mit Sauer¬ stoff in einer Konkurrenzreaktion reagierenden Agens (R) nach einem der Ansprüche 1 bis 4. 10. Furnace for the thermal treatment of materials, in particular electric arc furnace, with an exhaust line (12) connected to a furnace vessel (2) and a feed line (28) opening into the exhaust line (12) for supplying at least one reducing effect and / or at least a reacting with sour ¬ material in a competing reaction agent (R) according to one of claims 1 to. 4 11. Ofen nach Anspruch 10, mit einer in das Ofengefäß (2) mündenden weiteren Zufuhrleitung (30) zum Zuführen des Agens11. Oven according to claim 10, with a in the furnace vessel (2) opening further supply line (30) for supplying the agent (R) · (R) · 12. Ofen nach Anspruch 10 oder 11, mit einem an die Abgasleitung (12) angeschlossenen Probenentnahmesystem (18) zum Zuführen einer Gasprobe (SG) an eine Analyseeinrichtung (20) zum Messen des Gehalts an Stickoxiden und/oder des Gehalts an Wasserstoff H2, Kohlenmonoxid CO, Methan CH4 oder Harnstoff CO(NH)2 und Weiterleiten eines diesen Gehalt wiedergebenden Messwertes (M) an eine Steuereinrichtung (24) zum Erzeugen eines Steuersignals (Sl, S2) für eine über die Zufuhrleitung (28) an die Abgasleitung (12) angeschlossene Dosiereinrich- tung (26) und gegebenenfalls für eine über die weiter Zufuhrleitung (30) an das Ofengefäß (2) angeschlossene weitere Do¬ siereinrichtung (32) zum Zudosieren des Agens (R) in Abhängigkeit vom Messwert (M) . 12. Oven according to claim 10 or 11, with a to the exhaust pipe (12) connected to the sampling system (18) for supplying a gas sample (SG) to an analysis device (20) for measuring the content of nitrogen oxides and / or the content of hydrogen H 2 , Carbon monoxide CO, methane CH 4 or urea CO (NH) 2 and forwarding a measured value (M) representing this content to a control device (24) for generating a control signal (S1, S2) for one via the supply line (28) to the exhaust gas line (12) connected Dosiereinrich- device (26) and optionally for a further on the further supply line (30) to the furnace vessel (2) connected further Do ¬ siereinrichtung (32) for dosing the agent (R) in dependence on the measured value (M). 13. Ofen nach Anspruch 12, mit einer Temperaturmesseinrichtung (22) zum Messen der Temperatur (T) am Ort der Probenentnahme und Weiterleiten dieser Temperatur (T) an die Steuereinrichtung (24), in der das Steuersignal (Sl, S2) für die Dosiereinrichtung (26) und gegebenenfalls vorhandene weitere Dosiereinrichtung (32) in Abhängigkeit von dieser Temperatur (T) und dem Messwert (M) ermittelt wird, wobei ein die Zudo- sierung des Agens (R) bewirkendes Steuersignal (Sl, S2) aus¬ schließlich dann erzeugt wird, wenn diese Temperatur (T) einen vorgegebenen Wert überschreitet. 13. A furnace according to claim 12, comprising a temperature measuring device (22) for measuring the temperature (T) at the location of sampling and forwarding this temperature (T) to the control device (24) in which the control signal (Sl, S2) for the metering device (26) and optionally existing further metering device (32) in dependence on this temperature (T) and the measured value (M) is determined, wherein the Zudo- tion of the agent (R) causing control signal (Sl, S2) then finally ¬ is generated when this temperature (T) exceeds a predetermined value. 14. Ofen nach Anspruch 12 oder 13, bei dem die Zufuhrleitung (28) in Strömungsrichtung des Abgases (OG) gesehen nach der Probenentnahmestelle in die Abgasleitung (12) mündet. 14. Oven according to claim 12 or 13, wherein the supply line (28) in the flow direction of the exhaust gas (OG) opens after the sampling point in the exhaust pipe (12) opens.
PCT/EP2012/056022 2011-04-27 2012-04-03 Method for reducing the emission of nitrogen oxides in the exhaust gas of a furnace during the thermal treatment of materials and furnace operated according to said method Ceased WO2012146462A1 (en)

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