EP0967434B1 - Burner with concentric air ducts and central stabilizer - Google Patents

Abstract

The system (11, 15, 4, 5) uses four conduits that are arranged in a pipe. The conduits are arranged in a concentric manner to allow the pipe to require as small a space as possible. The conduits allow for an efficient filtering process to take place allowing the effective dead zone of the filter system to be minimal. The system is easily installed in any IC engine.

Description

The present invention is an improvement to burners comprising at least three air supply ducts, two of which axial and rotating, concentric with at least one supply of fuel, and a central stabilizer.

The technical sector of the invention is the production of burners can use one or more fuels, simultaneously or not, with special arrangements for supply conduits gas, said gas possibly being air or a combustible gas.

The main application of the invention is its use in burners for rotary tube furnaces in which air from primary combustion is brought to more than 80% by at least two concentric conduits arranged around any supply conduit fuel and through a third central supply duct in which is injected with at most 20% of primary air remaining.

In a preferred embodiment, the two so-called conduits concentric annulars supplying more than 80% of primary air said burners, feed these one in the form of an air stream swirling with flow components peripheral, and the other in the form of an axial air stream comprising substantially axial flow components; which two primary air flow ducts are therefore arranged radially at the exterior of any fuel line, including in particular at less an annular pulverized coal supply duct; the central duct, inside which is slid at least one cane at least starting fuel supply, is partially closed by a flame stabilizer in the form of flange surrounding the central opening into which opens said rod, and has openings for the passage of a part of the primary combustion air, i.e. at most said 20% and even in fact 10% of this air, so that in the area central located downstream of said stabilizer, does not occur no significant fuel combustion, qualifying said zone death center; such a burner is described and claimed in European patent 421,903 published April 10, 1991 and filed by the same applicant as for the present invention.

The present invention can be considered as a improvement made to such burners and more generally any burner that can be described as modern, including fuel and air supply lines primary combustion according to the main application defined above, which conduits together form a nozzle intended for be mounted on an orifice provided for this in the wall of the enclosure forming the hearth of the oven or combustion chamber, and around which the secondary air is brought. These burners differentiate from older burners to which relates to that disclosed in US Patent 4,208,180 in which a fuel supply line is interposed between the annular primary air circulation duct swirling and the annular primary air duct to axial circulation.

The present invention therefore relates to a burner of the type comprising at least four substantially concentric conduits, these four conduits comprising a central supply conduit in primary air in which is placed at least one tube forming a central fuel supply duct, a duct fuel supply device which is located at the outside of the central primary air supply duct, a primary air supply duct for circulation substantially axial which is located outside of all fuel supply lines, and a conduit primary air supply which has partitions of orientation to create a swirling effect in the air, and which is located outside of all supply lines fuel, the burner comprising a central stabilizer placed at the outlet of the central air supply duct primary, surrounded by a tube, having openings in the through which the primary air from the duct opens central primary air supply, and overflowing radial direction relative to any central opening central supply duct fuel supply in fuel.

The objective of the present invention is not to have a central zone at the outlet of said central supply duct in primary air which is too reducing for the fuel of the makes only 20% maximum or even 10% of primary air injected into this area; this small proportion of air which is adjustable allowing indeed, as described in the patent previous recalled above to have a larger range of adjustment of the burner operating stage by moving the start of combustion and the flame to a greater distance in front of the center of the burner nozzle from processes and burners known prior to the EP patent 421,903.

According to the invention, the above objective is achieved by enriching the air and fuel mixture in the area central unit of such burners, comprising at least four ducts substantially concentric fuel supply and primary combustion air while respecting the proportion of less than 20% or even 10% of primary air injected into this central area; the others at least 80% of primary air is injected in axial air and in air rotated, by duct openings disposed outside any opening fuel outlet and said burner includes a central stabilizer placed at the outlet of a supply duct central primary air, which air flows through openings of said stabilizer; said stabilizer overflows in radial direction relative to any opening of a placed tube in said central primary air duct and inside from which a fuel can be injected, said central zone being the area in front of said central stabilizer by report to the burner nozzle; according to the invention this one has at least one additional gas supply opening into said stabilizer, around said opening at any diameter between any tube inside which can be injected with fuel through the stabilizer and the outer tube delimiting the central air intake duct primary.

Thus, according to the invention, the burner of the aforementioned type has at least one additional supply opening in gas located outside any central supply duct in fuel and inside the tube surrounding the central stabilizer.

In a particular embodiment, said supply additional gas is a fourth air supply primer to promote the mixing of air and fuel in said central area, the air mixture and fuel in this area being below the proportion stoichiometric.

In another particular embodiment, said gas supply is an additional gas supply combustible, such as natural gas or low power gas heat.

When said gas supply is a fourth primary air supply, this can be achieved by a opening arranged in said central stabilizer and supplied by the central primary air supply duct, without specific duct of actual food distinct from that of this central primary air.

In a particular embodiment this fourth primary air supply can be achieved through an opening peripheral disposed around the outer edge of said stabilizer, which opening can be either directly carried out in said central stabilizer without specific duct as shown previously and as shown in Figure 6 attached, or delimited by the outer tube surrounding said stabilizer and a tube concentric internal; these two said tubes then constituting a supply duct independent of other air supplies primary.

In other embodiments, adapted either to a additional fuel gas supply i.e. a fourth primary air supply, said additional gas supply is carried out, independently of any other gas supply, at through a concentric tube outside the one inside which can be injected any fuel in the central area: this is what embodiment which is shown by way of example in the most of the attached figures.

The result thus makes it possible to obtain an improvement in burners comprising at least three air supply ducts, of which two axial and rotating, concentric with at least one fuel supply, and a central stabilizer, and allowing achieve the objective explained above, namely to enrich the air / fuel mixture earlier in the central burner area downstream of the stabilizer, either by reducing the reducing nature of the air / fuel mixture in this zone, either by improving said mix, or both, while retaining the benefits of tuning and of operation of the burners, to which this perfecting and therefore improving its specific qualities.

La figure 1 est une demi-vue en coupe longitudinale simplifiée d'un exemple de brûleur selon l'invention et utilisé, à titre d'exemple de l'application principale, mais non limitative, comme perfectionnement d'un brûleur tel que décrit dans le brevet EP 421 903.

La figure 2 est une demi-vue en coupe partielle de la partie centrale de l'exemple de réalisation du brûleur suivant la figure 1 avec une particularité supplémentaire.

Les figures 3a et 3b sont des demi-vues en coupe simplifiées et limitées à la seule sortie de l'ouverture d'alimentation en gaz additionnelle et suivant deux possibilités de réglage.

La figure 4 est une vue de face de la sortie de ladite ouverture d'alimentation en gaz additionnel.

Les figures 5a et 5b sont respectivement des vues en coupe longitudinale et de face des brûleurs selon l'invention, comportant plusieurs cannes d'alimentation en combustible dans son conduit central.

La figure 6 est une demi-vue en coupe partielle de la partie centrale d'un brûleur suivant l'invention avec une seule quatrième alimentation en air primaire, situé à la périphérie du stabilisateur et délimitée par le conduit central.

Les figures 7 à 11 sont des demi-vues en coupe longitudinale partielle et en vue de face de l'extrémité de l'alimentation additionnelle en gaz selon l'invention suivant différents modes de réalisation.

The description and the figures below represent an embodiment of the invention but are in no way limiting; other embodiments are possible within the scope and scope of the invention which can in fact adapt to other types of burners having the main characteristics recalled above and defined below.

FIG. 1 is a simplified longitudinal sectional half-view of an example of a burner according to the invention and used, by way of example of the main application, but not limiting, as an improvement to a burner as described in EP 421 903.

Figure 2 is a partial sectional half-view of the central part of the embodiment of the burner according to Figure 1 with an additional feature.

Figures 3a and 3b are simplified sectional half-views and limited to the single outlet of the additional gas supply opening and according to two adjustment possibilities.

Figure 4 is a front view of the outlet of said additional gas supply opening.

Figures 5a and 5b are respectively longitudinal and front sectional views of the burners according to the invention, comprising several fuel supply rods in its central duct.

Figure 6 is a partial sectional half-view of the central part of a burner according to the invention with a single fourth primary air supply, located at the periphery of the stabilizer and delimited by the central duct.

Figures 7 to 11 are half-views in partial longitudinal section and in front view of the end of the additional gas supply according to the invention according to different embodiments.

The present invention thus applies to any burner with at least four ducts 11 ', 15', 4 ', 5' substantially concentric fuel supply and primary combustion air, comprising axial air and the air set in rotation, and a central stabilizer 3 placed at the outlet of a central primary air supply duct 11 ' emerging through openings 13 passing through said stabilizer, these openings can be calibrated holes circular, or slits, or any other shape; which stabilizer overflows in a radial direction relative to any opening 14 of a 10 '' tube placed in said air duct 11 'central primary and inside which can be injected fuel such as a supply rod 10 for a liquid fuel or by pneumatic transport directly in said conduit 10 'for any pulverulent solid fuel such as pulverized combustible waste that we want incinerate; all of said conduits and stabilizer form a nozzle 1 of axis XX '.

Combustion 2 therefore takes place downstream from the outlet of this nozzle 1 around which the secondary air is supplied. A general exterior representation of an example of a burner complete can be viewed according to Figure 1 of the European patent 421,903.

The nozzle 1 of axis XX 'as described in this patent constitutes a preferred embodiment of the following burner the invention: the peripheral outlet openings 4, 5 of the primary air supply ducts 4 ', 5' are arranged radially outside any duct opening 14, 15 10 ', 15' fuel, either directly through a conduit central 10 ', by a rod 10 located in this central duct 10' or by a 15 'peripheral conduit, into which is sent preferably pulverized coal or any fuel gaseous. Said peripheral outlet openings 4, 5 supply the nozzle 1 with axial air and swirling air through at least two concentric 4 ', 5' conduits, and the conduit central 11 ', is partially closed by a stabilizer flame 3 in the form of a flange surrounding the opening 14 through which opens said rod 10.

Said flame stabilizer 3 can be a plate of circular outer shape matching the inner shape of the central primary air supply duct 11 ′: it comprises the orifices or openings 13 for the passage of part of this primary combustion air which with that possibly supplied by the opening, or additional openings, 6 according to the present invention, represents at most 20% of this air primary in such a way that in the central zone 2 located in downstream of said stabilizer 3, no combustion takes place significant fuel, qualifying said central zone 2 of dead.

Preferably, the quantity of primary air which is never null, and sent to said central dead zone 2 is included between 0.1% and 20% of the total primary air and preferably less than 10%, and the proportion of air of primary combustion is between 2 and 10% of the total air combustion and preferably less than 6%.

The flame stabilizer 3 is preferably offset axially behind the set of openings concentric outlets of primary air and fuels solid or gaseous. This stabilizer 3 is arranged at the end before 10 "tubes inside which can be injected fuel, such as by supply rods 10 liquid fuel which are then slid into these 10 "tubes.

The axial air outlet opening 5 is that located as radially as possible on the outside of all ducts primary air supply and has an outer edge 8 which protrudes axially forward and constitutes the internal edge of the hub of nozzle 1, the external 5 "tube of this conduit 5 'is itself surrounded by concrete 7 for external protection.

The axial air outlet opening 5 is constituted by the ends of the walls of the 4 "and 5" tubes which may be, at least for that of the 4 "internal tube, conical in shape divergent and may include partitions of orientation and separation of this axial air into several outlet orifices.

The radial air outlet opening 4 consists of the ends of the walls of the 15 "and 4" tubes which can be also conical and divergent, has partitions of orientation to create the swirling ejection effect of this air;

In the embodiments shown in FIGS. 1, 2, 3 and 5, opening 6 of the additional gas supply is performed independently of any other gas supply or in air, through a 6 "tube concentric outside that 10 "inside which all fuel can be injected and whose orifice constitutes said opening 14.

According to the examples of representation of FIGS. 3 and 7 to 11, at least one of the 6 ", 10" tubes constituting said conduit 6 'of additional gas supply is movable relative to the other tube. If the inner 10 "tube is otherwise shrinkage from the 6 'tube, especially when injected direct pulverulent solid fuel into said 10 "tube, this fuel is enriched before it leaves through opening 14; this is represented in all of Figures 7 to 11. According to Figure 11 the opening 6 of the additional gas supply is completely free then that in FIGS. 7 to 10, this opening 6 includes devices 9, 16 for at least partial sealing of said opening :

According to Figures 7a and 7b, the outer tube 6 " delimiting said additional supply duct 6 ' has an inner end flange 16, as the rest Figures 8; this flange allows by moving the inner tube 10 "maximum forward to fully seal this additional opening 6; further back from this flange 16 end allowing total closure, it can be arranged partitions 9 allowing by their inclination inject the additional gas in a guided manner following any desired direction, which then converges anyway towards the inside of the 10 'tube and can be further rotation.

According to the embodiment of Figures 8 to 8d in addition closure devices 16 and orientation 9 of the outlet gas, end of additional supply line 6 ' may have behind partitions 9, a partition circular peripheral 19 surrounding the 10 "outer tube of the conduit 10 'and pierced with radial holes 18 allowing inject additional gas, drawing back the 10 "tube until discovering said orifices; more according to section VIII VIII ' as shown in Figure 8c, this partition peripheral 19 may include notches, plumb or downstream of said orifices 18, so that the gas penetrates preferably through the orifices 18 when they are discovered before the rest of this gas is directed through the partitions 9.

According to the exemplary embodiments of FIGS. 9 and 9b, 10a to 10c, said inner end flange 16 may include orifices 17 inclined for injecting gas at angles which may be different, as shown particularly in FIGS. 10a to 10c : in particular the section X ₁ X ' ₁ corresponds to FIG. 10c with a large angle of inclination relative to the axis XX' of the burner, and the section X ₂ X ' ₂ corresponds to FIG. 10b with an angle d lower inclination.

These different embodiments as well as the possibility of mobility of the central tube 10 "allows to obtain different types of adjustment of the additional gas injection into the fuel supplied by line 10 'in order to optimize and promote the subsequent combustion of it.

According to the mode of representation of FIGS. 3a and 3b in which is also the outer tube 10 "of the conduit 10 ' which is mobile, we have two orientation devices and shutter 9, 16 at least partially of opening 6 such that can be noted in front view according to section IV IV 'of the Figure 3b for the devices inside the duct 6 '; said shutter devices 9 also making it possible to ability to rotate feed stream in additional gas. In addition in this exemplary embodiment the end of the tube 10 "has a flange 16 'located downstream of the outer tube 6 "and whose surface 16" constituting the inner wall of the end of the duct 6 'is shaped divergent conic, which allows on the one hand to orient, in spreading it, the gas flow and on the other hand by variation of the opening X between the respective end edges of the tubes 6 ', 10 "to vary the flow and / or speed of this injection of additional gas.

According to another embodiment shown in the Figure 2, said opening 6 for additional gas supply may consist of at least one side by the end of a divergent wall of a tube 6 ", 10", 11 ", said end of said wall being in the form of a divergent truncated cone of angle α ; each of the walls in this case the 6 ", 10" tubes can form different angles, respectively α2, α1.

Likewise and at the opposite corner opening, said opening 6 additional gas supply can be made at less than one side by the end of a converging wall of a tube 6 ", 10", 11 "said end of the wall being shaped truncated cone converging angle β; the end of the two said walls can form different angles β2, β1.

According to the exemplary embodiments of FIGS. 5, the burner may include in its central part several fuel supply pipes passing through the central supply pipe 11 ′ in primary air and opening out through the stabilizer 3; it may be at least in part of a conduit 10 _'1 is possible to drag a liquid fuel supply rod 10 _one on the other at least a conduit 10' to ₂ of directly injecting powdered solid fuel therein as indicated above, and finally a conduit 12 constituting in fact the igniter of the burner to start the combustion of the fuels in the other conduits. According to the invention, said burner can then comprise as many openings 6 of additional gas supplies as it includes said fuel supply conduits 10 ′, 12; and each of the ends of said conduits can be equipped with one of the devices described in FIGS. 2 to 4 and 7 to 11 knowing that the igniter conduit 12 may not include such an opening 6 for additional gas supply.

Furthermore, for the additional gas supply conduits 6 ′, these being able to contain acid condensable elements such as H ₂ SO ₄ or HCl, it is important to avoid the excessive cooling and the condensation of these components against the walls of said ducts as they would cause corrosion and their rapid destruction; to avoid this, said walls can be insulated to prevent them from being colder than the temperature of the fuel; for this, it is possible to isolate either the walls of the primary air guide tubes from the guide tubes of the solid or gaseous fuel circuits, or the walls of these latter conduits. This thermal insulation can be carried out on the side not subject to abrasion of solid fuel or gas, and preferably consisting of a protective tube of small thickness, approximately 0.5 to 2 mm and either of felt paper or cardboard. insulation with very low thermal coefficient and a thickness of the order of 2 to 15 mm, or by spraying a deposit of special temperature-resistant paint having a thermal coefficient also very low.

All the devices according to the present invention can apply to any burner with known basic characteristics as described in the introduction and which may include other peripheral circuits (outside and around stabilizer 3) fuel supply in addition to that of pulverized coal 15 'which is the only one represented in the embodiment taken into account example attached.

Claims (15)

1. Burner comprising at least four substantially concentric ducts (4', 5', 11', 15'), these four ducts comprising a central primary air supply duct (11') in which there is placed at least one tube (10") forming a central fuel supply duct (10'; 10'₁; 10'₂; 12), a peripheral fuel supply duct (15') which is situated outside the central primary air supply duct (11'), a primary air supply duct with substantially axial circulation (5') which is situated outside all the fuel supply ducts (10'; 10'₁ ; 10'₂ ; 12, 15'), and a primary air supply duct (4') which comprises orientation partitions for creating a vortex effect in the air, and which is situated outside all the fuel supply ducts (10' ; 10'₁ ; 10'₂ ; 12, 15'), the burner comprising a central stabiliser (3) placed at the outlet from the central primary air supply duct (11'), surrounded by a tube (11"), comprising openings (13) through which the primary air coming from the central primary air supply duct (11') emerges, and projecting in the radial direction with respect to any central fuel supply opening (14) in a central fuel supply duct (10'; 10'₁; 10'₂; 12), characterised in that it comprises at least one additional gas supply opening (6) situated outside any central fuel supply duct (10'; 10'₁; 10'₂; 12) and inside the tube (11") surrounding the central stabiliser (3).
2. Burner according to Claim 1, characterised in that at least one of the additional gas supply openings (6) is supplied with fuel from a fuel supply source.
3. Burner according to Claim 1 or 2, characterised in that at least one of the additional gas supply openings (6) is supplied with primary air from a primary air supply source.
4. Burner according to Claim 3, characterised in that the opening in at least one additional primary air supply (6) is supplied by the central primary air supply duct (11').
5. Burner according to one of Claims 1 to 4, characterised in that the opening of at least one additional gas supply (6) is supplied by an additional gas supply duct (6') produced independently of any other gas supply duct (4', 5', 10'; 10'₁; 10'₂; 12, 13', 15') and delimited by an additional tube (6" ).
6. Burner according to Claim 5, characterised in that an additional gas supply duct (6') is delimited by the tube (11") surrounding the central stabiliser (3) and in that the additional tube (6") is internal to and concentric with the tube (11'') surrounding the central stabiliser (3) and delimits the corresponding additional gas supply duct (6') of the central primary air supply duct (11').
7. Burner according to Claim 5 or 6, characterised in that at least one additional gas supply duct (6') is delimited by a tube (10'') forming a central fuel supply duct (10'; 10'₁; 10'₂; 12) and in that the corresponding additional tube (6") is external to and concentric with this tube (10") forming a central fuel supply duct (10'; 10'₁; 10'₂; 12) and delimits this additional gas supply duct (6') of the corresponding central fuel supply duct (10'; 10'₁; 10'₂; 12).
8. Burner according to one of Claims 5 to 7, characterised in that one of the tubes (6", 10", 11") delimiting an additional gas supply duct (6') is able to move with respect to the other tube (10", 11", 6'') delimiting this same additional gas supply duct (6').
9. Burner according to one of Claims 1 to 8, characterised in that at least one additional gas supply opening (6) comprises devices (9, 16) adapted to at least partially close off this additional gas supply opening (6).
10. Burner according to one of Claims 1 to 9, characterised in that the axial end of at least one tube (6", 10", 11") delimiting an additional gas supply duct (6') and forming the additional gas supply opening (6) is a wall in the form of a divergent truncated cone.
11. Burner according to one of Claims 1 to 10, characterised in that the axial end of at least one tube (6") delimiting an additional gas supply conduit (6') and forming the additional gas supply opening (6) is a wall in the form of a convergent truncated cone.
12. Burner according to one of Claims 1 to 11, characterised in that at least one additional gas supply opening (6) comprises devices (9, 17, 18) adapted to guide the injection of the gas in any required direction.
13. Burner according to one of Claims 1 to 12, characterised in that the walls of the tubes (6", 10", 11'') delimiting all the additional gas supply ducts (6') are thermally insulated.
14. Burner according to one of Claims 1 to 13, characterised in that it comprises as many additional gas supplies (6) as there are central fuel supply ducts (10'; 10'₁; 10'₂; 12).
15. Burner according to one of Claims 1 to 14, characterised in that the primary air emerging from the orifices (13) and possibly from the additional gas supply openings (6) represents no more than 20% or even 10% of the primary air.

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