EP0967434A1 - 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 the 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 minus 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 flange-shaped flame stabilizer surrounding the central opening into which said rod opens, and has openings for the passage of part of the air from primary combustion or at most said 20% and even in fact 10% of this air. in such a way that in the central area located downstream from said stabilizer, no appreciable combustion of the fuel, qualifying said central dead zone; such a burner is described and claimed in European patent 421 903 published on 10 April 1991 and filed by the same applicant as for this invention.

The present invention can be considered as a improvement made to such burners and more generally to any burner that can be described as modern, with fuel and combustion air supply lines primary according to the main application defined above, which conduits together forming a nozzle intended to be mounted on a orifice provided for this in the wall of the enclosure forming the focus of the oven or combustion chamber, and around which air is brought secondary.

The objective of the present invention is not to have a zone central at the outlet of said central air supply duct primary which is too reducing for the fuel due to the only 20% maximum or even 10% of primary air injected into this zone ; this small proportion of air which is adjustable allowing in fact, as described in the prior patent mentioned above to have a larger range for adjusting the pace of burner operation by delaying the start of combustion and of flame at a greater distance in front of the center of the nozzle of the burner compared to known processes and burners prior to patent EP 421903.

According to the invention, the above objective is achieved by enriching the air and fuel mixture in the central area such burners, comprising at least four substantially ducts fuel and combustion air supply concentrics primary while respecting the proportion of less than 20% or even 10% of primary air injected into this central area; the others at less than 80% of primary air is injected in axial air and in air supplied rotation, through duct openings arranged outside of any fuel outlet opening and said burner comprises a central stabilizer placed at the outlet of an air supply duct central primary, which air emerges through orifices of said stabilizer; said stabilizer overflows in the radial direction by relative to any opening of a tube placed in said air duct central primary and inside which can be injected a fuel, said central area being the area in front of said central stabilizer with respect to the burner nozzle; according to the invention this comprises at least one additional power supply in gas opening into said stabilizer, around said opening at any diameter between any tube inside which can be injected fuel through the stabilizer and the outer tube delimiting the central primary air supply duct.

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

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

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 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 area of the burner downstream of the stabilizer, either by reducing the reducing nature of the air / fuel mixture in this area, either by improving said mixture, or both. while retaining the benefits of tuning and of operation of the burners, to which this perfecting and therefore improving its specific qualities.

The description and the figures below represent an example of the invention but have no limiting character; other realizations are possible within the scope and the scope of the invention which can indeed be adapted to other types of burners having the main characteristics recalled previously and defined below.

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

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

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

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

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

Figure 6 is a partial sectional half-view of the part central unit 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 longitudinal section partial and front view of the feed end additional gas according to the invention according to different modes of production.

The present invention thus applies to any burner comprising at least four ducts 11 ", 15", 4 ", 5" substantially fuel and combustion air supply concentrics primary, comprising axial air 5 'and air rotated 4', and a central stabilizer 3 placed at the outlet of a supply duct central primary air 11 ′ opening through orifices 13 passing through said stabilizer, these orifices being able to be holes calibrated circular, or slits, or any other form; which stabilizer overflows in a radial direction relative to any opening 14 of a 10 '' tube placed in said primary air duct central 11 'and inside which fuel can be injected such only by a supply rod 10 for a liquid fuel or by pneumatic transport directly in said conduit 10 'for any powdery solid fuel such as combustible waste pulverized that we want to 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 brought. A representation general exterior of a complete burner example can be consulted according to FIG. 1 of European patent 421 903.

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

Said flame stabilizer 3 can be a shaped plate circular exterior conforming to the interior shape of the duct central primary air supply 11 ′: it comprises the orifices or openings 13 for the passage of part of this combustion air primary which with that possibly supplied by the opening, or the additional openings, 6 according to the present invention, represents at most 20% of this primary air in such a way that, in the central zone 2 located downstream of said stabilizer 3, does not occur no significant fuel combustion, qualifying said zone death center 2.

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

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

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

The axial air outlet port 5 is constituted by the ends of the walls of the 4 "and 5" tubes which can be, at least for the internal 4 ", of divergent conical shape and capable of have partitions for orientation and separation of this axial air in several outlet ports.

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

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

• Suivant les figures 7a et 7b, le tube extérieur 6" délimitant ledit conduit d'alimentation additionnelle 6' comporte une bride d'extrémité 16 intérieure, comme du reste les figures 8 ; cette bride permet en déplaçant le tube intérieur 10" au maximum vers l'avant d'obturer totalement cette ouverture additionnelle 6 ; de plus en arrière de cette bride 16 d'extrémité permettant une obturation totale, il peut être disposé des cloisons 9 permettant par leur inclinaison d'injecter le gaz additionnel d'une manière guidée suivant toute direction souhaitée, qui est alors de toutes façons convergent vers l'intérieur du tube 10' et peut être de plus mis en rotation.
• Suivant l'exemple de réalisation des figures 8 à 8d en plus des dispositifs d'obturation 16 et d'orientation 9 de la sortie du gaz, l'extrémité du conduit 6' d'alimentation additionnelle peut comporter en arrière des cloisons 9, une cloison périphérique 19 circulaire entourant la paroi extérieure 10" du conduit 10' et percée d'orifices radiaux 18 permettant d'injecter le gaz additionnel, en reculant le tube 10" jusqu'à découvrir lesdits orifices ; de plus suivant la coupe VIII VIII' telle que représentée sur la figure 8c, cette cloison périphérique 19 peut comporter des échancrures, à l'aplomb ou à l'aval desdits orifices 18, afin que le gaz pénètre préférentiellement à travers les orifices 18 quand ils sont découverts avant que le reste de ce gaz soit dirigé à travers les cloisons 9.
• Suivant les exemples de réalisation des figures 9 et 9b, 10a à 10c, ladite bride d'extrémité intérieure 16 peut comporter des orifices 17 inclinés d'injection de gaz suivant des angles pouvant être différents, tels que représenté particulièrement sur les figures 10a à 10c : en particulier la coupe X₁ X'₁ correspond à la figure 10c avec un angle d'inclinaison important par rapport à l'axe XX' du brûleur, et la coupe X₂ X'₂ correspond à la figure 10b avec un angle d'inclinaison plus faible.

According to the examples of representation of FIGS. 3 and 7 to 11, at least one of the tubes 6 ", 10" constituting said duct 6 'for additional gas supply is movable relative to the other tube. If the inner tube 10 "is further back from the tube 6 '. Especially in the case of direct injection of powdered solid fuel into said tube 10', this fuel is enriched before it exits through the orifice 14 ; this is shown in all of FIGS. 7 to 11. According to FIG. 11, the additional gas supply 6 is completely free, whereas in FIGS. 7 to 10, this opening 6 comprises devices 9, 16 for closing at least partial of said opening:

• According to Figures 7a and 7b, the outer tube 6 "delimiting said additional supply conduit 6 'has an inner end flange 16, as the rest of Figures 8; this flange allows the inner tube 10" to be moved as far as possible the front of completely closing this additional opening 6; further behind this end flange 16 allowing total closure, partitions 9 can be arranged allowing their inclination to inject the additional gas in a guided manner in any desired direction, which is then anyway convergent towards the inside of the tube 10 'and can be further rotated.
• According to the embodiment of Figures 8 to 8d in addition to the closure devices 16 and orientation 9 of the gas outlet, the end of the duct 6 'for additional supply may behind partitions 9, a circular peripheral partition 19 surrounding the external wall 10 "of the conduit 10 'and pierced with radial orifices 18 making it possible to inject the additional gas, by drawing back the tube 10" until uncovering said orifices; moreover according to section VIII VIII 'as shown in FIG. 8c, this peripheral partition 19 can include notches, plumb or downstream of said orifices 18, so that the gas preferentially penetrates 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 setting the injection of additional gas into the fuel supplied by the 10 'conduit in order to optimize and promote the subsequent combustion thereof.

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. there are two orientation and shutter devices 9, 16 at least partial of the opening 6 'as can be noted with a view to face along section IV IV 'of FIG. 3b for the devices inside the 6 'duct; said closure devices 9 allowing also to be able to give a rotational movement to the flow additional gas supply. Also in this example of embodiment the end of the tube 10 "has a flange 16 'located in downstream of the outer tube 6 "and whose surface 16" constituting the wall inside of the end of the duct 6 'is conical in shape divergent, which allows on the one hand to direct, by spreading it, the flow gas and on the other hand by variation of the opening X between the edges respective ends of the tubes 6 ', 10 "to vary the flow rate and / or the speed of this additional gas injection.

According to another embodiment shown in FIG. 2, said opening 6 for additional gas supply can be formed at least on one side by the end of a divergent wall a 6 ", 10", 11 "tube, said end of said wall being shaped divergent truncated cone of angle α; each of the walls in the occurrence 6 ", 10" can form different angles, respectively α2, α1.

Likewise and at the opposite corner opening, said opening 6 at least additional gas supply on one side by the end of a converging wall of a 6 ", 10" tube, 11 "said end of the wall being in the form of a 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 conduits passing through the central supply conduit 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 additional gas supplies 6 as there are said fuel supply conduits 10 ', 12'; and each of the ends of said conduits can be equipped with one of the devices described in Figures 2 to 4 and 7 to 11 knowing that the igniter conduit 12 may not include such an additional gas supply conduit 6.

In addition, for the additional 6 'supply lines in gases, these may contain acid condensable elements such than H2S04 or HCL, it is important to avoid cooling exaggerated and the condensation of these components against the walls said conduits because they would cause corrosion and their rapid destruction; to avoid this, said walls can be insulated to prevent them from getting colder than temperature fuel; for this we can isolate either the walls of the tubes primary air guides with respect to the guide tubes of the solid or gaseous fuels, or the walls of the latter ducts. This thermal insulation can be carried out on the non subject to abrasion of solid fuel or gas, and preferably consisting of a thin protective tube, about 0.5 to 2 mm and either very low felt or insulating cardboard thermal coefficient and with a thickness of the order of 2 to 15 mm, i.e. by spraying a deposit of special paint resistant to temperature also having a very low thermal coefficient.

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 (13)

Burner with at least four ducts (11 ", 15", 4 ". 5") substantially concentric fuel supply and in primary combustion air. comprising axial air (5 ') and the air set in rotation (4 ') arranged outside any opening of fuel outlet (15, 14). and a central stabilizer (3) placed at the outlet of a central primary air supply duct (Il ') opening through orifices (13) of said stabilizer, which stabilizer overflows in a radial direction relative to any opening (14) of a tube (10 ") placed in said central primary air duct (Il ') and at at least the interior of which fuel can be injected, characterized in that it comprises at least one power supply additional gas opening into said stabilizer (3), and disposed around the outer edge of said stabilizer (3) and a conduit peripheral (15) inside the axial air duct (5 ') and rotation (4') and in which a fuel is sent. Burner according to claim 1 characterized in that said peripheral opening is delimited by the tube (11 ") surrounding said stabilizer (3) and a concentric inner tube. the two so-called tubes constituting an independent supply conduit other primary air supplies. Burner according to any one of claims 1 or 2 and comprising in its central part several conduits fuel supply opening through the stabilizer (3) characterized in that it comprises as much supply (6) additional gas it comprises of said supply pipes in combustible. Burner according to any one of Claims 1 to 3 characterized in that said gas supply is a fourth primary air supply (6). Burner according to claim 4 characterized in that this fourth primary air supply is carried out by a opening (6) supplied by the primary air supply duct (11 '). Burner according to any one of Claims 1 to 3 characterized in that said gas supply is a supply additional fuel gas. Burner according to claim 1 characterized in that said additional gas supply (6) is carried out independently of any other gas supply through a tube (6 ") concentric outside that (10") inside which can be injected any fuel through the opening (14). Burner according to any one of claims 2 or 7 characterized in that at least one of the tubes (6 ", 10") constituting said duct (6 ') for additional gas supply is movable by compared to the other tube. Burner according to any one of Claims 1 to 8 characterized in that the opening (6) for additional supply of gas has at least one closure device (9, 16) partially said opening. Burner according to any one of Claims 1 to 9, characterized in that the said additional gas supply opening (6) is constituted at least on one side by the end of a divergent wall of a tube (6 " , 10 " ₅ 11 '') said end of said wall being in the form of a divergent truncated cone. Burner according to any one of claims 1 to 10 characterized in that said additional supply opening (6) gas consists at least on one side by the end of a wall converging of a tube (6 ", 10", 11 ") said end of the wall being in the shape of a converging truncated cone. Burner according to any one of Claims 1 to 11 characterized in that the opening (6) for additional supply of gas comprises devices (9, 17, 18) for guided injection of said gas following any desired direction. Burner according to any one of Claims 1 to 12 characterized in that at least the walls of the air guide tubes primary are insulated from gas and fuel circuits solid which may contain acid condensable elements.

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