EP3428534A1 - Highly heat resistant, highly erosion resistant lance system, reaction space containing the lance system and method for reducing the concentration of pollutants in combustion gases - Google Patents

Abstract

The invention relates to a lance system (1) for introducing reagents (15) in the form of fluids into reaction spaces (2) through which combustion gases (3) flow, such as calciners, flue gas ducts or boilers, the lance system (1) comprising:
an inner portion (4) constructed to be disposed within the reaction space (2), and an outer portion (5) constructed to be located outside the reaction space (2),
wherein the lance system (1) comprises a cladding tube (6) and at least one inner tube (7), and wherein at least along the inner portion (4) of the lance system (1) the at least one inner tube (7) is disposed within the cladding tube (6) whereby a gap (8) is formed between the outer wall of the at least one inner tube (7) and the inner wall of the cladding tube (6),
wherein at least one outlet opening (9) is arranged in the peripheral wall of the jacket tube (6) along the jacket tube (6),
wherein the at least one inner tube (7) has outlet openings or nozzles (10) for injecting the reagent directly through the at least one outlet opening (9) of the jacket tube (6) outwards,
wherein the intermediate space (8) is in fluid communication with the outside via the at least one outlet opening (9) of the cladding tube (6),
according to the invention
the cladding tube (6) has an inner support tube (11) which is made of a heat resistant, heat and scale resistant, sintered, oxide dispersion strengthened metallic material, and that on the support tube (11) at least one outer highly wear resistant coating (12) Cladding is applied.

The invention further relates to a reaction space (2) containing the lance system (1) according to the invention and to a method for injecting reagents into combustion gases within a reaction space (2) through which these combustion gases flow with the aid of the lance system (1) according to the invention.

Description

The present invention relates to a high heat resistant, high erosion resistant lance system, a reaction space containing the lance system and a method for reducing the concentration of pollutants in combustion gases

Technical area

In the combustion of carbonaceous materials and fossil fuels, for example, in power plants and plants for steam generation, waste incineration plants, or cement plants sulfur dioxide (SOx) and nitrogen oxides (NO _x ). In accordance with the legal requirements, measures must be established to control the combustion process or to purify flue gases or combustion gases so that only little NO _x is produced or NO _x and SO _x present in combustion gases are reduced in order to reduce the input into the atmosphere ,

The formation of NO _x is subject to complex reaction mechanisms, the most important NO _x sources being the oxidation of the nitrogen of the combustion air (thermal NO _x ) and the oxidation of the fuel nitrogen (fuel NO _x ).

Thermal NO _x is formed essentially at temperatures greater than about 1200 ° C to 1500 ° C, because only at these temperatures, the molecular oxygen present in the air changes significantly into atomic oxygen (thermal oxidation) and with the nitrogen of the air combines. The rate of formation of the thermal NO _x depends exponentially on the temperature and is proportional to the oxygen concentration.

The primary nitrogen compounds contained in the fuel first disintegrate into secondary nitrogen compounds (simple amines and cyanides), which are competitively converted to either NO _x or N ₂ in the course of combustion. In the case of an oxygen deficiency, the formation of N _{2 is} preferred or the formation of NO _{x is} suppressed or even reversed. The formation of fuel NO _x is only slightly dependent on temperature and proceeds even at low temperatures.

In power plants, the reduction of NO _x in the prior art by means of primary measures such as the air grading takes place at the burner and above the furnace height. The air grading above the combustion chamber height is carried out in such a way that the burner belt area is usually operated under stoichiometry. Thus, the burners receive only part of the amount of air necessary for complete combustion. The remaining air needed for burnout (= ABL = burnout air) is then usually added at a considerable distance above the burner belt. This procedure is referred to as OFA (Over-Fire-Air). The addition takes place by means of so-called ABL nozzles. The two basic types of ABL nozzles are wall nozzles and ABL lances.

Application SNCR as a secondary measure for nitrogen oxide reduction

The invention relates to a method and devices including reaction chambers for the reduction of undesirable substances by injecting a reagent in an exhaust gas or flue gas, in particular in the exhaust gas of cement plants, in which the reagent is injected by means of lances in the flue gas. Furthermore, the invention relates to a lance or a lance system for the injection of reagent for the reduction of undesirable substances in the flue gas. In addition, the invention also relates to a suitable reaction space, which is equipped with such a device according to the invention in order to carry out the method can.

There are already known methods and devices of the aforementioned type. The reactants are, for example, ammonia and / or urea, which can reduce the proportion of nitrogen oxides in the flue gas. Corresponding methods are referred to as selective non-catalytic reduction (SNCR). In the selective non-catalytic reduction (SNCR) of nitrogen oxides, reducing agents in aqueous solution (typically ammonia water, urea) or gaseous (ammonia) are injected into the hot flue gases of an incinerator. The reaction of the reducing agent with nitrogen oxide and oxygen produces molecular nitrogen, water and carbon dioxide. In this case, for example, for ammonia or urea as a reducing agent, the following simplified reaction takes place:

4NH ₃ + 4NO + O ₂ → 4N ₂ + 6H ₂ O

2NH ₂ CONH ₂ + 4NO + O ₂ → 4N ₂ + 2CO ₂ + 4H ₂ O

The optimum temperature range for the execution of the reactions described is dependent on the flue gas composition between 900 and 1100 ° C.

One of the main difficulties of SNCR technology is to mix the reducing agent into the flue gas in the correct temperature window. Basically, the SNCR technology is successfully used in small and medium sized boilers and especially in waste incineration plants and cement plants. Here, the advantage lies in the small cross sections of the reaction or fire chambers, so that the SNCR technology is effective and optimized applicable.

In cement plants, cement is produced in a continuous dry process process in rotary kilns. The raw materials such as limestone, clay, sand, etc. are ground and dried at the same time then warmed up and then fired into cement clinker. The burning of the cement clinker takes place in rotary kilns, which are slightly inclined. As a result of inclination and rotation of the furnace, the preheated raw meal, which is at the upper end, runs against a pulverized coal, oil or gas flame which burns at the lower end of the furnace. In the area of the flame with gas temperatures of 1,800 to 2,000 ° C, kiln temperatures of 1,350 to 1,500 ° C are reached. The preheating and the calcination of the raw meal takes place either in the rotary kiln itself or in a separate preheater, which is usually constructed from a device consisting of several cyclones, or in a separate calciner (calcination reactor). The hot exhaust gases of the rotary kiln flow through the calciner and the preheater from bottom to top, and the dry raw meal is added to the exhaust gases before the top cyclone stage, separated in the individual cyclones from the gas and resuspended in the gas stream before the next cyclone stage. The raw meal is preheated in the preheater usually to a temperature of about 800 ° C. In the cyclone preheater can already be carried out a partial calcination of the raw meal. The further calcination of the raw meal then takes place in the calciner before it enters the rotary kiln.

In the rotary kiln form at the high temperatures of the combustion flame in a considerable amount of nitrogen oxides, which must be removed from the exhaust gases.

SNCR plants for power plants, waste incineration plants and cement plants have already been described in the prior art. As a rule, only very short injection lances are used, with the nozzles either closing substantially with the reactor wall or channel wall or not projecting more than a few decimeters into the hot space. The reason for this is that a temperature of 870 to 1,000 ° C is required for the functioning of a SNCR and a long lance of this temperature and especially for use in cement plants extremely high dust loadings in the flue gas and thus a strong Erosionsbelastung would be exposed.

The central areas of the flue gas streams in flue gas ducts and large-diameter combustion chambers in cross-section can be achieved, if at all, only by a high quantitative use of the reagents through wall-mounted nozzles. With increasingly stringent limit values for NO _x (eg <200 or even 150 mg / Nm ³ dry, based on 6% O ₂ ), the middle of the channel or combustion chamber must also be better achieved with reagent, with disproportionately high quantities for the SNCR be used on ammonia or urea solution. These remain in not inconsiderable amounts then, without having found a reactant, unreacted as so-called ammonia slip in the flue gas. Partly burns this ammonia slip in the episode, some of it leaves the gas chamber over the chimney. In addition, there is also the danger that larger amounts of unreacted ammonia get into the filter ash, which is undesirable due to the odor. In any case, the deployment costs increase significantly due to the non-earmarked contribution of non-input material involved in the reaction.

Thus, German Patent Application P 41 25 004.4 a process for denitrification of the resulting in the production of cement exhaust gases, in which the raw-laden exhaust gases are reacted at 300 to 450 ° C with NH ₃ in the presence of a catalyst, wherein as the catalytically active substance iron sulfate or a mixture of iron sulfate and Manganese sulfate is used. The NH ₃ and the catalyst particles are introduced into a line through which the combustion gas flows. The reaction takes place in said line and in the downstream cyclone. The injection nozzle for the ammonia is not described in detail in the document.

The DE 43 13 479 describes a method for denitrification of the resulting in the production of cement exhaust gases, wherein the exhaust gas after leaving the rotary kiln at a temperature of 750 to 950 ° C ammonia is added, and that the exhaust gas at a temperature of 300 to 450 ° C with a catalyst is contacted, containing as the active substance iron sulfate or a mixture of iron sulfate and manganese sulfate. The injection nozzle for the ammonia is not described in detail in the document.

The EP 0 854 339 also describes a process for denitrification of the resulting in the production of cement combustion gases, wherein the exhaust gas after leaving the rotary kiln in the reaction chamber of the calcination zone, an ammonia solution is added. The injection nozzle or an injection lance for the ammonia solution will not be described in detail.

The WO 93/19837 discloses a process for denitrification of the exhaust gases which arise in the production of cement. In this case, after leaving the rotary kiln, an ammonia solution is added to the exhaust gas via nozzles. There are compressed air nozzles Application comprising a tubular channel for supplying the ammonia water, a surrounding annular channel which is closed at the end and serves for supplying compressed air, an outlet opening, and a number of connection openings between the two channels.

The WO 2014/114320 describes a process for the treatment of exhaust gases containing nitrogen oxides from industrial processes, such as flue gases, for reducing the nitrogen oxide content by means of chemical reduction of the nitrogen oxides. The injection of the reducing agent in the reaction space through which the exhaust gases pass is effected via nozzles arranged in the wall of the reaction space.

The DE 197 81 750 T1 ( WO 97/41947 A1 ) discloses an injection lance for injecting anhydrous NH ₃ and air into a furnace. The lance consists of three tubes which are arranged one inside the other, wherein the ammonia is placed in the inner tube, at the inner end in the gap between the inner and middle tube passes where it coincides with separately supplied air and mixed with it. Through a plurality of openings, the ammonia / air mixture flows from the interior of the middle tube through radial channels, which bridge the gap between the middle and outer tube, in the flue gas of the boiler.

The document DE 10 2004 026 697 A1 discloses a method of injecting reductant together with the upper air. For this purpose, a part of the Ausbandluft is introduced with a second nozzle within which is simultaneously the injection nozzle for introducing nitrogen oxide reducing agent.

The EP 2 962 743 A1 discloses the introduction of reducing agent into a kettle. The reducing agent is injected by means of lances, in which one or more injectors for reducing agent are introduced, wherein these lances also, for example, burnout air is supplied. The reductant is injected into the ABL lance and exits the lance through the nearest exit ports of the lance into the flue gas. The document proposes several injectors with different ones Introduce penetration into the lances, which can then inject different amounts of reducing agent based on the present measurement data.

The US 5,342,592 discloses an injection lance having an outer tubular sheath with a plurality of openings and a cooling circuit. This tubular casing has an inner channel into which an injection lance is inserted. This in turn consists of an inner tube and an outer tube, wherein a gap is formed. The reducing agent is passed through the inner tube and the propellant through the gap. The reducing agent passes from the inner tube and branching over the gap bridging channels directly into the flue gas stream. The propellant meets at the outlet of these channels with the reducing agent and enters the flue gas stream.

The US 5,281,403 describes an injection lance system having an inner tube and an outer tube forming a gap through which the reducing agent is passed. At the inner end of the lance system, the reducing agent is fed into a conduit located in the inner cavity of the inner tube, the conduit being provided with a plurality of nozzles. In this inner cavity, a carrier gas is introduced. The nozzles of the conduit located within the internal cavity inject the reactant into the flue gas through a respective respective exit aperture in the injection lance system, the reagent being mixed simultaneously with the carrier gas which is directed into the internal cavity and the lance system also through said exit aperture leaves.

Injection lances, in particular for the injection of reagents for SNCR or other reagents or gases for use in reaction chambers (calcinators, flue gas ducts, boilers or fire chambers), which are flowed through by about 1000 ° C hot flue gases with high dust load and in some cases high speeds, have not been described so far.

Object of the invention

The object of the present invention was therefore to achieve a more effective flue gas cleaning effect, in particular with respect to SO _x and NO _x , in particular with moderate use of appropriate reagents, and in particular in reaction chambers such as calciners, flue gas ducts, boilers or fire chambers, of about 1000 ° C. hot flue gases are traversed with high dust load and sometimes high speeds, the corresponding reagents can be mixed into the combustion gas as evenly distributed.

• einen inneren Abschnitt konstruiert, um innerhalb des Reaktionsraums angeordnet zu werden, und einen äußeren Abschnitt konstruiert, um außerhalb des Reaktionsraums angeordnet zu werden,
• wobei das Lanzensystem ein Hüllrohr und mindestens ein Innenrohr aufweist, und wobei zumindest entlang des inneren Abschnitts des Lanzensystems das mindestens ein Innenrohr innerhalb des Hüllrohrs angeordnet ist, wodurch ein Zwischenraum zwischen der äußeren Wand des mindestens einen Innenrohrs und der inneren Wand des Hüllrohrs ausgebildet wird,
• wobei entlang des Hüllrohrs mindestens eine Austrittsöffnung in der Umfangswand des Hüllrohrs angeordnet ist,
• wobei das mindestens eine Innenrohr Austrittsöffnungen oder Düsen zum Eindüsen des Reagenz direkt durch die mindestens eine Austrittsöffnung des Hüllrohrs hindurch nach außen aufweist,
• wobei der Zwischenraum über die mindestens eine Austrittsöffnung des Hüllrohrs mit der Außenseite in fluider Kommunikation steht,
• wobei erfindungsgemäß
• das Hüllrohr ein inneres Tragrohr aufweist, das aus einem hochwarmfesten, hitze- und zunderbeständigen, gesinterten, Oxid-dispersionsverfestigten metallischen Werkstoff gefertigt ist, und
• auf das Tragrohr mindestens eine äußere hoch-verschleißbeständige Beschichtung mittels Auftragschweißen aufgebracht ist.

The technical object is achieved by a lance system for the introduction of reagents in the form of fluids in reaction spaces through which combustion gases flow, such as calciners, flue gas channels, boilers or fire chambers, the lance system comprising:

• constructed an inner portion to be disposed within the reaction space, and an outer portion constructed to be located outside the reaction space,
• wherein the lance system comprises a cladding tube and at least one inner tube, and wherein at least along the inner portion of the lance system the at least one inner tube is disposed within the cladding tube, thereby forming a gap between the outer wall of the at least one inner tube and the inner wall of the cladding tube,
• wherein at least one outlet opening is arranged in the peripheral wall of the cladding tube along the cladding tube,
• wherein the at least one inner tube has outlet openings or nozzles for injecting the reagent directly through the at least one outlet opening of the cladding tube to the outside,
• wherein the intermediate space is in fluid communication with the outside via the at least one outlet opening of the cladding tube,
• according to the invention
• the cladding tube has an inner support tube made of a high temperature, heat and scale resistant, sintered, oxide dispersion strengthened metallic material, and
• on the support tube at least one outer highly wear-resistant coating is applied by buildup welding.

As mentioned above, to reduce pollutant loading, reagents in the form of fluids, i. in particular in the form of gases and / or liquids, injected into combustion gases. The reaction chambers through which combustion gases pass are preferably calciners or calcining reactors, flue gas channels, boilers or fire chambers.

The support tube of the lance system according to the invention consists of a high temperature, heat and scale resistant, sintered, oxide dispersion strengthened metallic material, i. a steel or a superalloy.

The oxide dispersion strengthened (ODS) steel or alloy consists of a mixture of a refractory refractory alloy powder and a very finely ground refractory ceramic powder, preferably yttria (Y ₂ O ₃ ), zirconia ( ZrO _2. ) Or hafnium oxide (HfO ₂ ), particularly preferably yttrium oxide (Y ₂ O ₃ ). These oxide dispersion-strengthened materials therefore consist essentially of metallic base materials in which highly stable or inert oxides are incorporated in the finest distributed manner. These inert particles do not change until the melting point of the metallic matrix and are also insoluble in the melt. The refractory oxide prevents the migration of dislocations in the metallic material and therefore contributes to the high creep resistance, especially at high temperatures, for example, gases above 1000 ° C up to 1250 ° C.

Both components - the powder of a heat-resistant, heat-resistant alloy and the very finely ground powder of a high-melting ceramic - are intimately mixed, pressed and sintered at high temperatures, but without melting, during the manufacturing process. The result is a material with a sufficiently high strength at very high temperatures.

Here, the high temperature, heat and scale resistant sintered metallic material is an oxide dispersion strengthened steel or an oxide dispersion strengthened superalloy. A suitable and preferred oxide dispersion strengthened steel contains 70.0 to 80.0 wt% Fe, 0.0 to 10.0 wt% Al, 10.0 to 25.0 wt% Cr, 0.0 to 1.0% by weight of Ti and 0.05 to 1.5% by weight of oxides of one or more elements selected from the group Y, Zr, Hf, preferably Y.

In another preferred embodiment, the refractory, refractory, and refractory sintered oxide dispersion strengthened superalloy contains 65.0 to 80.0 wt% Ni, 10.0 to 20 wt% Cr, 0.5 to 10.0 % By weight of Al, up to 0.1% by weight of C, up to 0.5 Ti and up to 1.5% by weight of oxides of one or more elements selected from the group Y, Zr, Hf, preferably Y.

• PM 3000 (Nominale chemische Zusammensetzung in Gewichts-%): 67,0 Ni, 20,0 Cr, 6,0 Al, 3,5 W, 2,0 Mo, 0,15 Zr, 0,01 B, 0,05 C, 1,1 Y₂O₃;
• FeCrAIMo-Legierung (chemische Zusammensetzung in Gewichts-%): 20,5 bis 23,5 Cr, 5,0 Al, 3,0 Mo, 0,0 bis 0,7 Si, 0,0 bis 0,4 Mn, 0,0 bis 0,08 C, 0,5 bis 1,5 Y₂O₃, Rest Fe, insbesondere: 21,0 Cr, 5,0 Al, 3,0 Mo, 0,5 Y₂O₃, Rest Fe.

Particularly suitable and preferred metallic materials are the following materials having the stated chemical composition:

• PM 3000 (nominal chemical composition in weight%): 67.0 Ni, 20.0 Cr, 6.0 Al, 3.5 W, 2.0 Mo, 0.15 Zr, 0.01 B, 0.05 C, 1.1 Y ₂ O ₃ ;
• FeCrAIMo alloy (chemical composition in weight%): 20.5 to 23.5 Cr, 5.0 Al, 3.0 Mo, 0.0 to 0.7 Si, 0.0 to 0.4 Mn, 0 , 0 to 0.08 C, 0.5 to 1.5 Y ₂ O ₃ , balance Fe, in particular: 21.0 Cr, 5.0 Al, 3.0 Mo, 0.5 Y ₂ O ₃ , remainder Fe ,

The lance system according to the present invention is also highly resistant to erosion. This is achieved by the outer coating. In a preferred embodiment of the lance system, the outer highly wear resistant coating applied to the support tube comprises (i) hard particles, wherein the hard particles comprise at least one of carbides, nitrides, borides, silicides and oxides and solid solutions thereof, and (ii ) a binder that binds the hard particles together. The hard particles may comprise at least one transition metal carbide selected from carbides of titanium, chromium, zirconium, hafnium, tantalum, molybdenum, niobium and tungsten or solid solutions thereof. The hard particles may be present as single or mixed carbides and / or sintered cemented carbides.

In a further preferred embodiment of the lance system, the outer highly wear resistant coating applied to the support tube comprises hard particles containing one or more transition metal carbides or solid solutions thereof and a binder selected from the group consisting of cobalt, nickel, iron, and a binder heat-resistant alloy of iron, chromium and nickel with a content of cobalt. Preferably, the hard particles contain carbides of titanium, chromium, zirconium, hafnium, tantalum, molybdenum, niobium and tungsten or solid solutions thereof, wherein the binder is selected from the group consisting of cobalt, nickel, iron, preferably cobalt, and a refractory alloy Iron, chromium and nickel with a content of cobalt.

More preferably, the carbides are tungsten carbide and optionally molybdenum carbide or solid solutions thereof, and the binder is cobalt or a refractory alloy of iron, chromium and nickel having a content of cobalt. A particularly suitable and preferred highly wear-resistant coating or coating comprises or consists of tungsten carbide and optionally molybdenum carbide in a binder or a matrix consisting essentially of cobalt or a heat-resistant alloy of iron, chromium and nickel with a proportion of cobalt.

In a further preferred embodiment, the coating comprises 40 to 50 wt% tungsten carbide and 40 to 60 wt% at least one of iron, cobalt and nickel, more preferably cobalt or a refractory alloy of iron, chromium and nickel in an amount Cobalt.

The outer highly wear-resistant coating is applied by build-up welding and preferably has a thickness of at least 2.0 mm, more preferably 2.0 to 10.0 mm, and even more preferably a thickness of 2.0 to 3.5 mm up.

The refractory, heat, and scale resistant, sintered, oxide dispersion strengthened metallic material has very good properties for the construction of a cantilevered lance projecting into spaces swept by hot gases. The made of this metallic material support tube of the lance system provides thus ensuring the required strength properties and ensures that the self-supporting lance does not permanently bend or even break off over a length of for example 5 m over time due to their own weight and the attacking flow forces. In normal operation, this support tube is cooled by the constantly flowing inside the nozzle envelope air and does not even approach the temperature of the surrounding flue gas. However, if this cooling nozzle shroud fails, for example, if the associated fan fails, the sheath of an original flue gas temperature is exposed at the point at which the lance system injects reagents, eg, 870-1000 ° C for a period of at least several days, and thereby decreases no harm.

Reaction chambers, such as calciners, flue gas ducts or boilers or fire chambers, some of which have large cross sections, must be loaded with appropriate reagents completely over the entire cross section for optimal emission reduction. In comparison to the injection of reagents with nozzles arranged directly in the wall of these reaction chambers, as hitherto carried out in the prior art, a much more effective flue gas cleaning effect can be achieved with the lance system according to the invention and thus a smaller pollutant clean gas value with moderate use of reagents. With the lance system according to the invention, the reagents can now also be reached the central regions of the cross-section of reaction chambers, which hitherto could not yet be supplied with reagent. In the example of the SNCR, this means that due to the better accessibility also the center of the reaction space has a lower clean gas end value, for example NO _x and thus compliance with a stricter limit value (eg <200 or even <150 NO _x mg / Nm ³ dry, based on 6% O ₂ ) can be achieved without disproportionately having to use ammonia or urea solution, which then also in not inconsiderable amounts afterwards, without having found a reactant, unreacted as so-called ammonia slip in the flue gas remains at the fireplace , There is also the danger that larger amounts of unreacted ammonia get into the filter ash, which is undesirable because of the odor.

Furthermore, the lance system according to the invention can also be used in dust-laden and z.T. flowing at high speeds, just under 1,000 ° C hot combustion gases are used because it is resistant to erosion over long periods in dusty environments, thermally-mechanically resistant and at the same time corrosion resistant to flue gas components and the remaining residual oxygen. According to the invention, this object is achieved in that the tube is constructed of two layers - the support tube and the coating applied to the support tube as described above.

1. a) Absorptionsmittel zur Rauchgasentschwefelung von Verbrennungsgasen, oder
2. b) Reduktionsmittel zur selektiven nichtkatalytischen Reduktion von Stickoxiden in Verbrennungsgasen,

in die von Verbrennungsgasen durchströmten Reaktionsräume einzuführen.In a further preferred embodiment of the lance system, the lance system is constructed

1. a) absorbent for flue gas desulfurization of combustion gases, or
2. b) reducing agents for the selective non-catalytic reduction of nitrogen oxides in combustion gases,

to introduce into the reaction chambers through which combustion gases pass.

Further preferably, the lance system is constructed of combustion gases having a dust loading of 1 g / m ³ up to 800 g / m ³ at a volume flow of 10,000 to 2,000,000 m ³ / h, preferably from 30 g / m ³ up to 800 g / m ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, more preferably from 100 g / m ³ to 800 g / m ³ at a flow rate of 10,000 to 2,000,000 m ³ / h to flow around. The dust load of combustion gas streams in the furnace of power plants is typically from 1 g / m ³ up to 10 g / m ³ , while the dust load, for example in calcination reactors of cement works in the range of 100 g / m ³ up to 800 g / m ³ . Based on standard cubic meters (Nm ³ ), the lance system is constructed of combustion gases with a dust load of 1 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, preferably 30 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, more preferably from 100 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h flows around become. The dust load of combustion gas streams in the furnace of power plants is typically from 1 g / Nm ³ to 10 g / Nm ³ , while the dust loading is, for example in calcining reactors of cement works in the range of 100 g / Nm ³ to 1000 g / Nm ³ .

1. a) Reagenzien in Form eines fluiden Gemisches enthaltend Reduktionsmittel durch den Innenraum des mindestens einen Innenrohrs zuzuführen und von dort über Austrittsöffnungen oder Düsen direkt durch die Austrittsöffnung(en) des Hüllrohrs hindurch nach außen zu leiten; sowie
2. b) Hüllluft in den Zwischenraum zwischen dem mindestens einen Innenrohr und dem Hüllrohr getrennt zuzuführen;
3. c) das Gemisch enthaltend Reduktionsmittel aus a) und die Hüllluft aus b) durch die Austrittsöffnungen im Hüllrohr aus dem Hüllrohr austreten zu lassen.

In a further preferred embodiment, the lance system is constructed,

1. a) reagents in the form of a fluid mixture containing reducing agent through the interior of the at least one inner tube supply and from there via outlet openings or nozzles directly through the outlet opening (s) of the cladding tube to pass through to the outside; such as
2. b) supplying enveloping air into the intermediate space between the at least one inner tube and the cladding tube separately;
3. c) to let the mixture containing reducing agent from a) and the sheath air from b) through the outlet openings in the cladding tube from the cladding tube.

The measure according to b), according to which enveloping air is fed separately into the intermediate space between the inner tube and the cladding tube, means that air is not supplied here or not only via the inner tube, but rather via a feed which is inherent to the cladding tube.

It is further preferred that this envelope air supply be located in the outer portion of the lance system, which is constructed to supply the space between the inner tube and the cladding tube with the cladding air. Thus, the cladding tube has an inner end and an outer end, the outer end being in fluid communication with a supply for introducing the cladding air into the interspace.

The enveloping air introduced via the intermediate space between the cladding tube and the inner tube of the lance system serves, as mentioned above, for cooling the lance system. The sheath air is introduced in the outer portion of the lance system in the cladding tube and forwarded in the space between the inner tube and cladding tube. The cladding air finally passes through the outlet openings in the cladding tube to the outside (into the interior of the reaction space), wherein the cladding air surrounds the reductant injected at these outlet openings with this optionally mixed and finally hits the combustion gas. The enveloping air also prevents caking at the outlet opening or at the nozzle of the inner tube, by keeping possibly moistened and agglomerated dust particles.

With the lance system according to the invention, reagents, such as nitrogen oxide reducing agents or sulfur dioxide absorption agents, can be mixed into a combustion gas as evenly as possible.

The cladding tube may have one or more inner tube (s). The inner tube preferably runs substantially over the entire length of the cladding tube in the inner portion. The end of the inner tube (inner end) located in the inner portion of the lance system, which is preferably closed, can touch the end of the cladding tube, which is also located in the inner portion, but will generally have a certain distance therefrom.

As already explained above, at least one or more or even a plurality of outlet openings is arranged in the peripheral wall of the cladding tube along the cladding tube.

The number and positioning of the outlet openings of the cladding tube depends on the flow conditions, the flow form of and the volume flow of the combustion gas in the reaction chamber (calciner, boiler or furnace, flue gas tube) and at what point in the cross section of the reaction space which amounts of reagent (reducing agent; ) is needed. Accordingly, the number, arrangement and size of the outlet openings may vary. In a preferred embodiment, the peripheral wall of the cladding tube has an outlet opening. The outlet opening or nozzle of the inner tube is arranged so that the reagent injects directly through the outlet opening in the cladding tube into the interior of the reaction space.

The one or more inner tubes arranged inside the cladding tube are preferably connected to the cladding tube. More preferably, the inner tube (s) will, at some locations within the cladding tube, be connected thereto by fixed connections, e.g. Fins connected to hold the inner tube (s) in place.

In a preferred embodiment, the cladding tube has a round or circular cross-section.

In a preferred embodiment of the lance system, the diameter of the cladding tube decreases in the direction of the inner end. This measure serves to maintain the velocity of the mass flow in the gap and to reduce the weight of the lance system. This measure will usually be necessary only for longer lances. The rejuvenation of the cladding tube can be carried out continuously or in stages. In a further embodiment, the diameter of the inner tube or of the inner tubes can also be reduced in the direction of the inner end.

Due to the arrangement of the at least one inner tube in the cladding tube at least along the inner portion of the lance system, a gap between the inner tube and cladding tube is defined, which extends over the entire circumference of the inner tube. Furthermore, it is preferable that the gap between the outer wall of the inner tube and the inner wall of the cladding tube extends over the entire length of the inner tube. The inner end of the inner tube is firmly and liquid-tightly connected to the nozzle head or the nozzle, in particular screwed.

The supply of the reducing agent may be carried out as a single-fluid nozzle when only the reducing agent is introduced or as two-fluid nozzles when the reducing agent is introduced together with a propellant (preferably compressed air). In an advantageous and preferred manner, inner tube has a central conduit for the supply of the reducing agent, and a gap between the central conduit and the inner wall of the inner tube, via which a propellant (compressed air) is passed separately from the supply of the reducing agent to in the Outlet or nozzle of the inner tube to be mixed with the reducing agent and to atomize this.

In preferred embodiments, the axes of the outlet openings of the cladding tube are aligned in the direction of the combustion gas flow or inclined at most by an angle of 20 ° to 30 °.

A further preferred embodiment of the lance system is designed so that the distance between inner tube and cladding tube is maintained by spacers, wherein these spacers are preferably selected from the group consisting of fins, pins, rods, webs or baffles.

The present invention further provides a reaction space designed to be passed through combustion gases, wherein the reaction space contains at least one lance system as described above according to the invention; wherein the inner portion of the lance system is disposed within the reaction space, and the outer portion of the lance system is disposed outside the reaction space. Reaction chambers, such as calciners, flue gas channels or boilers or fire chambers, which in some cases have large cross sections, can now be subjected to appropriate reagents over the entire cross section with the device according to the invention. Thus, with the device according to the invention, the reagents required for pollutant reduction can now also reach the central regions of the cross section of these reaction chambers as well as in dust-laden and z.T. flowing at high speeds, about 1000 ° C hot combustion gases are injected.

In a preferred embodiment of the reaction space, the inner portion of the at least one lance system cantilevers into the interior of the reaction space and preferably has a length of at least 0.5 m, preferably a length of at least 1.0 m, more preferably a length of at least 2 , 0 m, even more preferably a length of at least 3.0 m, and more preferably a length of at least 4.0 m. Furthermore, it is preferred that a length of 5.0 m is not exceeded.

In another preferred embodiment, the reaction space is a calciner of a cement plant designed to allow the combustion gas passed directly or indirectly from a rotary kiln to flow through the calciner and in the opposite direction to feed raw meal through the calciner for calcining towards the rotary kiln. The rotary kiln then produces the cement clinker.

Depending on the type of calciner or calcining reactor, the lance systems can be arranged horizontally or vertically in the boiler. Preferably, the lances are arranged horizontally, as calciner is usually flowed through vertically. Due to the strength of the lance systems according to the invention, the lance systems according to the invention can be mounted cantilevered.

The reducing agent is guided into the interior of the inner tube and passes through the outlet openings or nozzles of the inner tube to the outside. Furthermore, enveloping air is also supplied via the lance system by directing it into the cladding tube, i. is passed into the space between the inner tube and cladding tube. The reducing agent is injected from the outlet openings or nozzles of the inner tube through the outlet openings in the cladding tube in the combustion gas stream, wherein the reducing agent is also surrounded by cladding air flowing from the space between the inner tube and cladding tube through the outlet openings in the cladding tube in the combustion gas stream.

In a preferred embodiment, the calciner or calcination reactor has at least one own fuel supply and at least one own combustion air supply.

In a preferred alternative embodiment, the reaction space is a boiler or a firebox, in particular of power plants and plants for steam generation and waste incineration plants, which furthermore contains at least one feed for fuel and at least one feed for combustion air. As a boiler or combustion chamber, the boiler contains, in addition to at least one supply for fuel, at least one supply for combustion air according to the invention, at least one of the lance systems described above; wherein the inner portion of the lance system is disposed within the vessel, and the outer portion of the lance system is located outside the vessel. In this case, the inner portion of the at least one lance system projects into the interior of the vessel in a cantilevered manner and preferably has a length of at least 0.5 m, preferably a length of at least 1.0 m, more preferably a length of at least 2.0 m more preferably one Length of at least 3.0 m, and more preferably a length of at least 4.0 m. Furthermore, it is preferred that a length of 5.0 m is not exceeded.

In the boiler or combustion chamber, fuel and combustion air are brought together to carry out the combustion. The resulting flue gas or combustion gas flows through the furnace and then through the subsequently arranged in the flue gas flow heating surfaces. The furnace is operated with air staging, so that the combustion air added to the burner is not sufficient for complete conversion of the fuel but substoichiometric. Above the burners, combustion air is added, for example, below the convective heating surfaces by means of wall nozzles for further combustion. In the area of the heating surfaces, below, in between or above, one or more lance systems according to the invention is or are arranged, which supply the nitrogen oxide reducing agent. Depending on the type of boiler, the lance systems can be arranged horizontally or vertically in the boiler. Due to the strength of the lance systems according to the invention, these can be mounted self-supporting. The reducing agent is guided into the interior of the inner tube and passes through the outlet openings or nozzles in the inner tube to the outside. Furthermore, enveloping air is also supplied via the lance system to the combustion gas by passing it directly into the cladding tube i. is passed into the space between the inner tube and cladding tube. Finally, the reducing agent passes through the outlet openings in the cladding tube in the flue gas stream. In this case, the reducing agent is also surrounded by enveloping air, which flows from the space between the inner tube and cladding tube through the outlet openings in the cladding tube in the combustion gas stream.

Advantageously, the supply for the reducing agent and the supply for the introduction of the air (sheath air) in the space between the inner tube and the cladding tube outside the reaction space (calciner, boiler, furnace, flue) are arranged. Furthermore, a supply for a propellant (compressed air) is preferably arranged in order to atomize the reducing agent at the outlet opening or nozzle of the inner tube.

In a further preferred embodiment of the reaction space (calciner, boiler, combustion chamber, flue gas channel) means are arranged upstream of the injection point, in particular baffles or swirl body to improve the mixing of the reducing agent with the combustion gas stream. These additional means located in the reaction space, such as baffles or swirlers, increase turbulence and result in improved and faster mixing. However, these baffles or delta wings may only be arranged upstream of the injection point, since they would otherwise be charged with the liquid droplets and would crust. Alternatively, these baffles or swirl body can be arranged downstream, so generally above the injection point, but they should then be at least 4 m, preferably at least 6 m away from the injection point, so that it can be safely assumed that all injected liquid is evaporated before the flow reaches the baffles. The advantage of the latter variant is that occasionally falling ash slabs from the ceiling of the firebox do not fall directly onto the nozzle lances. The baffles must also consist of heat-resistant and wear-resistant materials, such as the lances.

The arrangement of the lance system according to the invention in the reaction chamber depends on the prevailing temperatures of the combustion gas, in which the nitrogen oxide is to be reduced. The optimum temperature for the conversion of NO _x by the selective non-catalytic process is in the range of 870 ° C to 1100 ° C.

The orientation of the lance systems in the reaction space can be horizontal or vertical. In the preferred embodiments of the reaction space according to the invention, one or more lance systems according to the invention may be arranged. Particularly preferably, a plurality of lance systems are distributed uniformly over the inner cross section of the reaction space, so that each area of the combustion gas flow is achieved with the reducing agent. By arranging a plurality of lances and optionally a plurality of outlet openings along the cladding tube of the lance systems, a uniform distribution of the reducing agent is achieved. The lance systems can also be arranged one above the other in one or more horizontal planes, in particular in the case of horizontal alignment of the lance systems.

In a particularly preferred embodiment of the reaction space, a plurality of lance systems are arranged parallel to one another.

As already explained above, the lance systems can be arranged horizontally or vertically in the reaction space. In a horizontal arrangement of the lance system, the respective axis of an outlet opening in the cladding tube is also aligned horizontally or preferably upwardly with respect to the horizontal, i. in the flow direction of the combustion gas stream.

In both embodiments, the axes of the outlet opening are preferably aligned in the direction of the combustion gas flow.

The technical object is further achieved by a method for the injection of reagents in the form of fluids in combustion gases within a reaction chamber through which these combustion gases, wherein the reagents are injected by means of at least one lance system as described above in combustion gases which flow through the reaction space.

With the method according to the invention, reaction spaces, such as calciners, flue gas channels or boilers or fire chambers, which in some cases have large cross sections, can be subjected to appropriate reagents over the entire cross section. This means that with the method according to the invention, the reagents required for pollutant reduction can now reach the central areas of the cross section of these reaction spaces and these reagents also in dust-laden and z.T. flowing at high speeds, about 1,000 ° C hot combustion gases can inject.

In particular, a method is preferred, wherein the combustion gases or the lance system (s) with a dust loading of 1 g / m ³ up to 800 g / m ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, preferably 30 g / m ³ up to 800 g / m ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, more preferably from 100 g / m ³ flow up to 800 g / m ³ at a flow rate of 10,000 to 2,000,000 m ³ / h. Based on standard cubic meter (Nm ³⁾ is in particular a method is preferred wherein the combustion gases, the or lance system (e) with a dust loading of 1 g / Nm ³ to 1000 g / Nm ³ at a volume flow rate from 10,000 to 2,000,000 m ³ / h, preferably from 30 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, more preferably from 100 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h to be flowed around.

In another preferred method, the combustion gases circulate the lance system at a temperature in the range of 870 ° C to 1100 ° C, more preferably in the range of 870 ° C to 1000 ° C.

In particular, a method is preferred, wherein the injected reagent is a reducing agent for reducing the concentration of nitrogen oxides in the combustion gas.

In another preferred method, the reducing agent is injected into the combustion gas within a calciner of a cement plant, which is passed directly or indirectly from a rotary kiln and flows through the calciner, in the opposite direction raw meal through the calciner for calcination towards rotary kiln promoted becomes. The rotary kiln then produces the cement clinker.

In another preferred method, further combustion gas is produced in the calciner by combustion of a fuel.

1. a) Erzeugen eines Verbrennungsgases in einer Verbrennungszone wobei das Verbrennungsgas Stickoxide enthält;
2. b) Injizieren eines selektiven Reduktionsmittels in den Verbrennungsgasstrom innerhalb des Reaktionsraumes stromabwärts der Verbrennungszone gemäß a);
3. c) Reaktion des Reduktionsmittels mit den Stickoxiden unter Bildung von N₂.

Another preferred method for reducing the concentration of nitrogen oxides in a combustion gas includes the following steps:

1. a) generating a combustion gas in a combustion zone wherein the combustion gas contains nitrogen oxides;
2. b) injecting a selective reducing agent into the combustion gas stream within the reaction space downstream of the combustion zone according to a);
3. c) reaction of the reducing agent with the nitrogen oxides to form N ₂ .

According to the invention, the reducing agent is introduced via one or more lance systems in the reaction chamber, preferably in a calciner or calcining reactor of a cement plant, in a boiler or firebox of a power plant or a plant for generating steam or in a flue gas duct, wherein the reducing agent in about the inner tube of the respective lance system is supplied, then the reducing agent from the inner tube via nozzles or outlet openings of the inner tube is passed directly through the outlet openings of the cladding tube to the outside. Preferably, compressed air for atomizing the reducing agent is supplied separately via the inner tube into the nozzle or outlet opening of the inner tube, in which the atomization of the reducing agent and thus the injection takes place. In addition, air is guided into the intermediate space between the inner tube and the cladding tube (cladding air), where the cladding air surrounds the injected reaction medium at the outlet openings of the cladding tube. If necessary, it is mixed with the reactant and finally reaches the reaction space via the outlet openings of the cladding tube.

As a reducing agent for the reduction of nitrogen oxides, a nitrogen-containing compound is used, selected from the group consisting of urea, ammonia, cyanuric acid, hydrazine, ethanolamine, biuret, triuret, ammelides, ammonium salts of organic and inorganic acids (for example, ammonium acetate, ammonium sulfate, ammonium bisulfite, ammonium bisulfite, Ammonium formate, ammonium carbonate, ammonium bicarbonate, ammonium nitrate, ammonium oxalate), preferably urea or ammonia. The reducing agent is preferably fed into the lance system, in particular into the inner tube, in aqueous solution (for example ammonia water or urea dissolved in water) or in gaseous form (ammonia).

In a preferred method, the reducing agent is mixed at or in the outlet opening or nozzle of the inner tube with separately supplied compressed air for atomizing.

In a further preferred method, the additional air (shell air) supplied separately through the intermediate space between the inner tube and the cladding tube has a temperature of 200 ° C. to 400 ° C.

In a further preferred method, the reducing agent reducing agent in the reaction space is preferably mixed with the combustion gas by means of appropriately arranged baffles and spin bodies.

In a preferred embodiment of the method, the reducing agent, when exiting the cladding tube of the lance system, encounters combustion gas having a temperature in the range from 870 ° C. to 1100 ° C., more preferably in the range from 870 ° C. to 1000 ° C.

In another preferred alternative method, the injected reagent is a flue gas desulfurization absorbent for reducing the concentration of sulfur dioxide in the combustion gas.

The reduction of the concentration of sulfur dioxide (desulfurization) in the combustion gas takes place by the combustion gas is sprinkled with a mixture of water and limestone (absorbent), whereby the sulfur dioxide is largely absorbed by chemical reactions. The gaseous sulfur dioxide first goes into solution in the absorption liquid. The reaction of sulfur dioxide with limestone finally produces calcium sulphite and CO ₂ . The loaded with calcium sulfite wash or absorbent suspension is collected in a container or Absorptionsmittelsumpf and by blowing air creates a gypsum suspension, which can be suspended by means of agitators to avoid deposits and withdrawn for further processing.

• Figur 1 zeigt einen schematischen Längsschnitt durch einen Reaktionsraum in der Bauart eines Kalzinators.
• Figur 2 zeigt einen Längsschnitt durch das erfindungsgemäße Lanzensystem.
• Figur 3 zeigt einen Querschnitt durch einen Kalzinator in der Ebene der Düsen bzw. Lanzen.

The invention will be described in more detail with reference to FIGS.

• FIG. 1 shows a schematic longitudinal section through a reaction space in the design of a calciner.
• FIG. 2 shows a longitudinal section through the lance system according to the invention.
• FIG. 3 shows a cross section through a calciner in the plane of the nozzles or lances.

FIG. 1 shows a schematic longitudinal section through a reaction chamber 2 in the design of a calciner. Coming from a rotary kiln (not shown) of a cement plant combustion gas 3 passes from below into the calciner 2. In the in FIG. 1 1, nitrogen oxide reducing agent 15 possibly together with propellant 14 (eg compressed air) in outside of the calciner 2 feeds (not explicitly shown) out into the interior of the inner tube 7 via two inventive horizontally extending, cantilevered lance systems. Further air (enveloping air) 13 is also supplied via the lance system 1 to the combustion gas 3 by being conducted in the outer portion 5 of the lance system 1 in the cladding tube 6 and finally in the gap 8 between the inner tube 7 and sheath 6. The nitrogen oxide reducing agent finally exits via nozzles from the inner tube 7. The ducted air 13 conducted via the intermediate space 8 between the inner tube 7 and the jacket tube 6 surrounds this injected stream of reducing agent 15 at the outlet opening 9 in the jacket tube 6, possibly causing mixing. Finally, the reducing agent 15 and the enveloping air 13 pass through the outlet openings 9 in the cladding tube 6 into the interior 19 of the calciner and impinge on the combustion gas 3.

FIG. 2 represents a longitudinal section through the lance system according to the invention. Within a reaction chamber, such as a calciner or boiler, lance systems 1 (shown here only a lance system) protrude horizontally and cantilevered into the interior of the reaction chamber, the (inner) wall is denoted by 16. The lance system 1 has an inner portion and an outer portion 5. The inner portion of the lance system 1 projects through the wall 16 of the calciner into its interior. The lance system has an inner tube 7 and a cladding tube 6. According to the in FIG. 2 shown type, only a single inner tube 7 is housed in the cladding tube 6. Depending on the design, however, several differently long inner tubes 7 can be arranged in a cladding tube 6. With the help of the inner tube 7 reducing agent 15 is passed through the lance system 1 and injected via one or more nozzles 10 in the combustion gas 3. In the illustrated construction, the inner tube 7 includes a central conduit 17 which carries the reducing agent 15 (or a reducing agent / propellant mixture). Between the central conduit 17 and the inner wall of the inner tube 7, a gap 18 is formed, is passed through the compressed air 14, which later serves for sputtering of the reducing agent in the nozzle 10. In the nozzle 10, reducing agent 15 and the compressed air 14 introduced separately via 18 are mixed and injected into the intermediate space 8 between inner tube 7 and jacket tube 6 or directly through the opening 9 in the jacket tube 6 into the interior of the calciner.

About the lance system 1 more air u.a. supplied for cooling the lance system by being guided in the outer portion 5 of the lance system 1 in the cladding tube 6 and finally in the gap 8 between the inner tube 7 and sheath 6. The enveloping air finally passes through the outlet openings 9 in the cladding tube 6 in the interior 19 and surrounds at these outlet openings 9, the injected reducing agent and is optionally mixed with this and finally meets the combustion gas 3. In addition to cooling the envelope air also serves to caking to prevent the nozzle 10 and the cladding tube 6 by keeping possibly moistened and agglomerated dust particles.

According to the invention, the cladding tube 6 an inner support tube 11, which is made of a high heat, heat and scale resistant, sintered, oxide dispersion strengthened metallic material. Furthermore, at least one outer highly wear-resistant coating 12 is applied to the support tube 11 by means of build-up welding.

The oxide dispersion strengthened (ODS) steel or alloy consists of a mixture of a powder of a conventional high temperature refractory alloy and a very finely ground high melting ceramic powder, preferably yttria (Y ₂ O ₃ ). These oxide dispersion-strengthened materials consist essentially of metallic base materials, in which highly stable or inert oxides are finely dispersed become. These inert oxide particles do not change up to the melting point of the metallic matrix, are also insoluble in the melt and prevent the migration of dislocations in the metallic material and therefore contribute to high creep resistance especially at high temperatures, for example gases above 1000 ° C up to 1,250 ° C at.

The outer highly wear-resistant coating 12 applied to the support tube 11 by build-up welding contains hard particles comprising one or more transition metal carbides, such as titanium, chromium, zirconium, hafnium, tantalum, molybdenum, niobium and tungsten carbides, in a matrix or binder of cobalt, nickel or iron. A particularly suitable coating 12 contains or consists of tungsten carbide and optionally molybdenum carbide in a binder or a matrix consisting essentially of cobalt or else a heat-resistant alloy of iron, chromium and nickel with a certain amount of cobalt.

This combination of a high temperature, sintered, oxide dispersion strengthened metallic material for the support tube 11 and the highly wear resistant coating 12 has very good properties for the construction of a cantilevered lance system 1 which projects into spaces through which hot gases 3 flow. The support tube 11 of the lance system 1 thus ensures the required strength properties and ensures that the self-supporting lance system 1 does not permanently bend or tear. The lance system 1 according to the invention can also be used in dust-laden and z. T. flowing at high speeds, just under 1,000 ° C hot combustion gases 3 are used because it is thermally-mechanically resistant and at the same time corrosion resistant to flue gas components and the remaining residual oxygen over long periods of time. In the normal case, the lance system 1 in particular the cladding tube 6 is cooled by the nozzle enveloping air flowing in the intermediate space 8, the atomizing compressed air 14 flowing in the intermediate space 18 and the liquid in the central conduit 17, so that in normal operation only a temperature of up to a few hundred degrees C, for example, 300 ° C or 400 ° C is expected. In the event of failure of this cooling, the high temperatures are normally critical to the cladding tube 6. According to the measures of the present invention Invention, the lance system 1 and the cladding tube 6 can withstand the very high temperatures of 870 ° C to 1100 ° C for a long time.

FIG. 3 shows a cross section through a calciner in the plane of the nozzles or lances.

The left-hand illustration shows a cross section through a calciner in the plane of the nozzles according to the conventional technique. For SNCR systems so far only very short injection lances have been used, the nozzles either substantially complete with the reactor or duct wall or protrude no more than a few decimeters in the flow of hot combustion gases interior. From the left-hand illustration it can be seen that due to the wall-mounted arrangement of the nozzles, the spray cones can only adequately cover or treat the flue gas flow.

The self-supporting lance according to the present invention, on the other hand, can be made longer in length so as to protrude into spaces through which hot gases flow (see right-hand illustration of FIGS FIG. 3 ). In the present example (see also example 1 and 2), four lance systems, each with a 1.0 m length end nozzle, were placed on a horizontal plane into the calciner of a cement works having an inside diameter of about 3.6 m attached. The right-hand illustration shows that with the aid of the lance according to the invention, calciners for the optimal reduction of pollutants can be charged completely with appropriate reagents over the entire cross-section. Therefore, in comparison to the injection of reagents with arranged directly in the wall of these reaction chambers nozzles, as done in the art so far, with the lance system according to the invention a much more effective flue gas cleaning effect and thus a smaller pollutant clean gas value can be achieved with moderate use of reagents. Thus, the reagents can now be achieved with the lancet system according to the invention, the central regions of the cross section of reaction chambers, which could not yet be supplied with reagent.

The invention will be explained in more detail with reference to the following examples.

Examples Example 1: Use of the lance system according to the invention in the calciner of a cement works and investigation with regard to its stability

The calciner of a cement works with an inside diameter of approx. 3.6 m was equipped with four injection lances arranged on a horizontal plane. They were so dimensioned that the inner lance section, which protruded into the interior of the calciner, had a length of 1.0 m. The nozzle was located at the end of the lance. The lance system used had an outer cladding tube with a diameter of 69 mm with a total wall thickness of 7.5 mm, which was constructed for wear protection reasons of two layers. The inner support tube of the cladding tube had a thickness of 5 mm and consisted of the heat-resistant, heat-resistant, sintered, oxide-dispersion strengthened metallic material Kanthal APMT from Sandvik (FeCrAIMo alloy, nominal chemical composition in weight%: 21, 0 Cr, 5.0 Al, 3.0 Mo, 0.5 Y ₂ O ₃ , balance Fe). The outside of the support tube had a 2.5 mm thick outer high-wear coating called Co-800-T from Eipa (4% C, 16% Cr, 4.5% Co, 4.5% Mo, 4% Nb, 1.5% W, 0.7% V, 0.9% B, remainder Fe) applied by build-up welding.

With the lance systems, an ammonia water and later also a urea solution in the combustion gas of the calciner for each 6 to 9 h was experimentally injected to reduce the NO _x content (results see example 2). The lances were exposed to a flue gas stream with an average dust load of 900 g / Nm ³ , a volume flow of 120,000 m ³ / h and at a temperature in the range of 850-930 C.

After the test, the lance systems were pulled out of the calciner and the cladding tube was measured. The cladding tube showed no changes in dimensions or damage. Furthermore, no distortion and no curvature of the cladding tube was detected. On the outside of the cladding deposits were measured with a thickness of about 1 cm. It should be noted that this did not correspond to the actual thickness of the deposits, because when pulling out of the lances through the narrow nozzle opening of the protruding part of the deposits was stripped.

According to the investigations, the lance system has proved extremely stable despite the extreme conditions in the calciner and a length of 1 m.

Example 2: NOx reduction by injecting an aqueous ammonia solution into the combustion gas in a calciner of a cement plant

In this example, the effect of the injection by means of the lances according to the invention on the NO _x content in the flue gas and on the consumption of ammonia water in comparison to the injection by means of the conventional technique was shown. The injection by means of wall nozzles was already in the description of FIG. 3 (left figure). For conventional SNCR plants in calciner very short injection lances have been used, the nozzles substantially complete with the reactor or duct wall or do not protrude into the flowed through by hot combustion gases interior. The injection of NO _x reducing reagent in this embodiment was the comparative example.

In contrast to conventional walled nozzles, the cantilevered lance according to the present invention could be made longer for use in cement works calciners (see right hand illustration of FIGS FIG. 3 ). With the help of the lance according to the invention, the calciner of a cement plant as described in Example 1 was subjected to optimum pollutant reduction completely over the entire cross section with appropriate reagents (ammonia water in this example).

Table 1 summarizes the results obtained with regard to the reduction of NO _x levels in the flue gas and the amounts of reagent used to achieve the corresponding NO _x levels and the conditions. The results show that the consumption of reagents could be reduced by injection via the lance systems according to the invention, as well as the NO _x content in the flue gas could be further reduced. <b> Table 1: </ b> Experimentation with highest NOx values from the furnace, caused by pure hard coal fire, without fluidized bed operation or lean gas Long-term test under normal cement plant conditions, ie with fluidized bed operation plus lean addition of gas and lignite as a supporting fire Ammonia water consumption l / h 24.9% sol. Nitrogen oxide (NOx) contents in raw and clean gas, reference: standard conditions, ie 0 ° C, dry, 10% O ₂ Ammonia consumption and efficiency (= degree of separation in [%]) Nitrogen oxide (NOx) contents in raw and clean gas, reference: standard conditions, ie 0 ° C, dry, 10% O ₂ Efficiency = degree of separation [%] existing SNCR system (prior art, 4 wall nozzles) > 1000 l / h (maximum flow) Raw gas value: approx. 700-800 mg / Nm ³ 608 l / h (high consumption) Raw gas value measured: 480 mg / Nm ³ (limit value is reliably maintained) Efficiency: 59% 310 mg / Nm ³ Efficiency: 60% 190 mg / Nm ³ Steinmüller Engineering - test facility (according to the invention, 4 lances each with 1.0 m length) 749 l / h Raw gas value: approx. 700-800 mg / Nm ³ 380 l / h (very moderate consumption) Raw gas value measured: 480 mg / Nm ³ Efficiency: 75% 185 mg / Nm ³ (the new limit value will definitely be undercut) Efficiency: 61% 185 mg / Nm ³ (limit value will be met safely)

LIST OF REFERENCE NUMBERS

1

lance system

2

Reaction space (calciner, boiler / firebox, flue gas duct)

3

combustion gas

4

inner section of the lance system

5

outer section of the lance system

6

cladding tube

7

inner tube

8th

Interspace between cladding tube and inner tube

9

Outlet opening of the cladding tube

10

Outlet openings / nozzles of the inner tube

11

support tube

12

coating

13

Supply of sheath air within the cladding tube (gap between inner tube and cladding tube)

14

Supply of compressed air inside the inner tube

15

Reagent (reducing agent or absorbent)

16

Wall of the reaction chamber

17

Central management

18

Interspace between inner tube and central line

19

Interior of the reaction chamber

Claims (15)

A lance system (1) for introducing reagents (15) in the form of fluids in reaction spaces (2) through which combustion gases (3) flow, wherein the lance system (1) comprises: an inner portion (4) constructed to be disposed within the reaction space (2), and an outer portion (5) constructed to be located outside the reaction space (2), wherein the lance system (1) comprises a cladding tube (6) and at least one inner tube (7), and wherein at least along the inner portion (4) of the lance system (1) the at least one inner tube (7) is disposed within the cladding tube (6) whereby a gap (8) is formed between the outer wall of the at least one inner tube (7) and the inner wall of the cladding tube (6), wherein at least one outlet opening (9) is arranged in the peripheral wall of the jacket tube (6) along the jacket tube (6), wherein the at least one inner tube (7) has outlet openings or nozzles (10) for injecting the reagent directly through the at least one outlet opening (9) of the jacket tube (6) outwards, wherein the intermediate space (8) is in fluid communication with the outside via the at least one outlet opening (9) of the cladding tube (6), characterized in that the cladding tube (6) has an inner support tube (11) which is made of a heat-resistant, heat and scale resistant, sintered, oxide dispersion-strengthened metallic material, and in that on the support tube (11) at least one outer highly wear-resistant coating (12 ) is applied by cladding. The lance system (1) according to claim 1, characterized in that the outer highly wear resistant coating (12) comprises hard particles containing at least one of carbides, nitrides, borides, silicides and oxides, especially transition metal carbides, and solid solutions thereof, and a binder, which combines the hard particles selected from the group consisting of cobalt, nickel, iron and a refractory alloy of iron, chromium and nickel with a content of cobalt. The lance system (1) according to claim 1 or 2, characterized in that the lance system (1) is constructed a) absorbent (15) for flue gas desulfurization of combustion gases (3), or b) reducing agent (15) for the selective non-catalytic reduction of nitrogen oxides in combustion gases (3), to introduce into the reaction chambers (2) through which combustion gases (3) flow. The lance system (1) according to any one of claims 1 to 3, characterized in that the lance system (1) is constructed of combustion gases (3) with a dust load of 1 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, preferably from 30 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, more preferably from 100 g / Nm ³ up to 1000 g / Nm ³ flows around at a flow rate of 10,000 to 2,000,000 m ³ / h. The lance system (1) according to any one of claims 1 to 4, characterized in that the lance system (1) is constructed a) reagents (15) in the form of a fluid mixture containing reducing agent through the interior of the at least one inner tube (7) and from there via outlet openings or nozzles (10) directly through the outlet opening (s) (9) of the cladding tube (6) therethrough to lead to the outside; such as b) supplying separated air (13) into the intermediate space (8) between the at least one inner tube (7) and the cladding tube (6) separately; c) the mixture containing reducing agent from a) and the sheath air (13) from b) through the outlet openings (9) in the cladding tube (6) to emerge from the cladding tube (6). A reaction space (2) designed to be passed through combustion gases, characterized in that the reaction space (2) contains at least one lance system (1) according to any one of claims 1 to 5; wherein the inner portion (4) of the lance system is disposed within the reaction space (2), and the outer portion (5) of the lance system (1) is disposed outside the reaction space (2). The reaction space (2) according to claim 6, characterized in that the inner portion (4) of the at least one lance system (1) cantilevered into the interior (19) of the reaction space (2) protrudes, and preferably a length of at least 0.5 m, preferably has a length of at least 1.0 m, more preferably a length of at least 2.0 m, even more preferably a length of at least 3.0 m, and particularly preferably a length of at least 4.0 m. The reaction space (2) according to claim 6 or 7, characterized in that the reaction space (2) is a calciner of a cement plant which is designed to allow the combustion gas (3) passed directly or indirectly from a rotary kiln to flow through the calciner and in the opposite direction raw meal through the calciner to promote calcination in the direction of rotary kiln. The reaction space (2) according to any one of claims 6 to 8, characterized in that the reaction space (2) is a boiler, further comprising at least one feed for fuel and at least one feed for combustion air. Method for injecting reagents (15) in the form of fluids into combustion gases (3) within a reaction space (2) through which these combustion gases (3) pass, characterized in that the reagents (15) are produced by means of at least one lance system (1) according to any one of Claims 1 to 5 are injected into combustion gases (3), which flow through the reaction space (2). The method according to claim 10, characterized in that the combustion gases (3) or the lance system (s) (1) with a dust load of 1 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, preferably from 30 g / Nm ³ up to 1000 g / Nm ³ at a flow rate of 10,000 to 2,000,000 m ³ / h, more preferably from 100 g / Nm ³ up to 1000 g / Nm ³ at a flow rate 10,000 to 2,000,000 m ³ / h flow around. The method of claim 10 or 11, characterized in that the combustion gases (3) flow around the lance system (1) at a temperature in the range of 870 ° C to 1100 ° C, more preferably in the range of 870 ° C to 1000 ° C , The method according to any one of claims 10 to 12, characterized in that the injected reagent (15) is a reducing agent for reducing the concentration of nitrogen oxides in the combustion gas (3). The method according to claim 13, characterized in that the reducing agent (15) is injected into the combustion gas (3) within a calciner (2) of a cement plant which is directly or indirectly passed from a rotary kiln and flows through the calciner (2), in the opposite direction raw meal through the calciner (2) is promoted for calcination in the direction of rotary kiln. The method according to any one of claims 10 to 12, characterized in that the injected reagent (15) is a flue gas desulfurization absorbent for reducing the concentration of sulfur dioxide in the combustion gas (3).

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