FI58014C - SAETT ATT BRAENNA FLYTANDE KOLVAETEN I EN BRAENNARE OCH ANORDNING FOER UTFOERANDE AV SAETTET - Google Patents

Description

RÄSFn [B] (11) NOTICE OF ADVERTISEMENT

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Patent- och registerstyrelsan 'Araftku utltgd och uti.skrtft «n pubikarad 31 07 * 80 (32) (33) (31) Requested« tuolkuut -t «| trd prtorfcvt 10.02 * 72 USA (US) 225259 (71) Blueray Systems, Inc., 22 Jericho Turnpike, Mineola, New York 11501, USA (72) Frank W. Bailey, East Orange, New Jersey, USA (7 ^) Forssen & Salomaa Oy (5 * 0 Method for burning liquids hydrocarbons in the burner and equipment for carrying out the process - Sätt att bränna flytande kolväten i en brännare och anordning för utförande av sättet

The invention relates to a method of burning liquid hydrocarbons in a burner comprising an open sleeve at the rear, the outlet of which leads to a combustion chamber into which liquid fuel is injected from the nozzle into the injection zone in the sleeve. to the entrance of the sleeve and then to the entrance of the sleeve.

The invention further relates to a device for burning liquid hydrocarbons for use in carrying out the method, the device comprising a sleeve with a rear open inlet and an outlet leading to a combustion chamber in a liquid-cooled heat exchanger, a nozzle for feeding a liquid fuel cloud to said sleeve, a plurality of sleeve a plurality of air jets are conducted to the inlet and through the sleeve, and a duct through which gaseous combustion products are again circulated from the combustion chamber to the inlet and through the sleeve.

This invention relates to blue flame burners and a heat exchange process and apparatus for burning a hydrocarbon liquid to produce a stable blue flame with low nitric oxide discharge and low particle discharge (Bachrach).

With regard to the state of the art related to the present invention, reference is made to the inventor's U.S. Patent No. 3,545,902 and DE Patent No. 1,177,271. The present invention is based in particular on the aforementioned U.S. patent, in which the described burner is intended to provide a blue flame. combustion of combustible liquid hydrocarbon fuel.

The aforementioned DE Patent Publication No. 1,177,271 bypasses the present invention, although this reference does not refer to combustion producing a blue flame, nor does it refer to the use of several combustion air jets in a mixing chamber. The DE patent therefore discloses a single ring-shaped inlet.

The method according to the invention is mainly characterized in that the fuel injection zone is arranged close to the mouth of said sleeve, that said nozzle is cooled by a smaller part of the combustion air, after which a smaller part of this combustion air is allowed to flow directly into the fuel injection zone. that the recycled gaseous combustion products are subjected to a heat exchange with a liquid-cooled heat exchanger to cool the recyclable gaseous products, and that said combustion air jets are mixed with the recyclable gaseous products in a mixing zone it reaches said fuel injection zone, which results in a stable blue flame in the combustion chamber with low content of nitrogen oxides and particles.

The device according to the invention, in turn, is essentially characterized in that said nozzle is arranged at the front of the sleeve to form a fuel injection zone at the sleeve outlet, the air tube extends through the sleeve inlet and the sleeve enters a smaller portion of combustion air in the vicinity of the nozzle they delimit an annular mixing zone inside the sleeve around the air tube, the openings being directed towards the annular mixing zone so that said plurality of air jets pass through the annular mixing zone and mix with the recycled liquid combustion zone to cool 3,5014 recirculated gaseous combustion products, resulting in a stable si in the combustion chamber; flame with a low content of nitrogen oxides and particles.

In the invention, most of the combustion air is preferably supplied in the form of strong jets directed through a dilution zone upstream of the fuel injection area leading to the combustion chamber. The strong jet effect produces reduced pressure when the jets enter the dilution zone, causing some of the gaseous combustion products to be recycled to this zone to dilute the air and chemically modify it before it encounters the fuel jet. preferably below 426 ° C before entering the dilution zone. A smaller portion of the combustion air cools the fuel injector and then enters the fuel injection area in the form of jets directed toward the combustion chamber. This results in an efficient and stable, blue flame with relatively little excess oxygen and diffuse combustion without local, hot areas that would cause greater NO formation, and without transient instabilities in ignition or start-up. Many common air and oil treatment components can be used directly in the practice of this invention, e.g., fuel pumps, fans, engines, and fuel injectors.

In the following, the invention will be described in detail with reference to some application examples of the invention shown in the figures of the accompanying drawing, to which the invention is not limited.

Figure 1 shows a side elevational view of an embodiment of the invention.

Figure 2 shows a cross-sectional view taken along line 2-2 of Figure 1.

Figure 3 shows a top view along line 3-3 of Figure 1.

Figure 4 shows an enlarged view of the parts of Figure 1.

Figure 5 shows a cross-sectional view taken along line 5-5 of Figure 1.

Figure 6 shows a cross-sectional view of a burner according to the invention connected to a people with a different heat exchanger and a fluid heating system.

4 58014

Figure 7 shows a cross-sectional view of a burner according to the invention connected to a second heat exchanger and a fluid heating system.

Figures 8 and 9 show graphical diagrams of the results obtained from the evaluation experiments comparing the oil burner according to the present invention to a previously known ordinary burner burning with a yellow flame.

As can be seen from Figure 1, the blue flame burner and heat exchange system of the invention includes a burner 10 with a barrel directed to a heat exchanger 12 connected to a water heater or boiler or hot air heater 14. The term "fluid heater" means heaters for water, steam and air or other fluid heat exchangers.

The burner 10 includes a housing 16 attached to the mounting flange 18 by a connection port 20 attached to the opening of the fluid heater 14 instead of a conventional yellow flame burner.

The housing 16 includes a lower portion 24 on which an electric motor 26 (Fig. 2) is mounted and whose fan wheel 28 is mounted on a shaft 30 inside the housing portion 24. Mounted on the housing part 24 is a fluid supply device 32 which includes a liquid hydrocarbon fuel pump driven by a shaft 30, whereby the liquid fuel is supplied via a line 34.

The adjustable screw 36 adjusts the fuel supply through the conduit 38 and the tube 40 having the connection 42 to the axial fuel conduit 44 (Figure 1) extends forward to the fuel injector 46 shown in the form of an injector.

To disengage the nozzle and the ignition electrode coupling, the tube 40 is releasably located in the recesses 49 in the housing 16 (Fig. 1) and the coupling includes a detachable coupling 39 (Fig. 3).

The housing 16 includes a top 50. The ignition transformer 52 is mounted on a cover 54 hinged at 56. The mounting flange 58 is located on the front of the top 50.

According to Figure 2, the housing part 50 forms a line for the pressurized air coming from the fan wheel 28. Air enters the fan wheel 28 through the air intakes 60 in the lower housing 24. The coil 62 discharges compressed air through the fan outlet 64 to the upper housing 50. The pressure generated by the fan 28 is available in the upper housing 66. The combustion air passes from the filling chamber 66 through a fixed partition 68 (Figure 1) . The end portion 5 of this partition 5 58014 70 has a plurality of apertures 72 disposed concentrically around the larger central aperture 74. The arcuate slot 76 (Figure 5) extends partially around the central opening. The side portion 78 of the septum 68 fits snugly within the tubular portion 20. The flange 80 of this partition contacts the mounting flange 18, as shown in Figure 1.

Connected to the septum 68 is an adjustable (rotatable) septum 82 mounted on the support tube 84 (Figure 3). The adjustable septum has a plurality of openings 86 aligned with the corresponding openings 72 (Figure 5). The support tube 84 extends forward through the central opening 74 of the fixed septum (Fig. 4) and the support tube is concentrically around the burner axis.

At the front end of the support tube 84 is a ring 88 and a concentric sleeve 90 which supports the nozzle 46 and its fuel line 44 (see also Figure 3) on the fuel line 44 and forces the septum 82 against the wall 70. The spring 92 presses forward against the seat 95 (Figure 4) on the electrode support portion 96, which has a sleeve 97 surrounding the rear end of the support tube 84. The support 96 is wedged at 93 in the tube 84. The nozzle fuel line 44 is loosely located in the hole 98 which holds this line concentrically within the support tube 84.

As shown in Figure 4, the compressed air in the chamber 66 is divided into two parts in use, a smaller part 99 of which flows into the support tube 84 through a plurality of small openings 100 located behind the partition 68. The majority of the compressed air 101 flows forward through the openings 72, and the flow portion 101 thus forms a plurality of equally spaced, spaced apart strong jets of air 102 directed forward into the annular zone 104 surrounding the support tube 84 in front of the septum 68. Said lower part of the combustion air flow 99 is preferably less than about 15% of the majority of the air flow 101. The two air streams 99 and 101 preferably form all the combustion air supplied to the combustion chamber 106 connected to the heat exchanger 12 (Fig. 1).

To adjust the main air flow 101, the electrode support portion 96 has an arm 108. The adjusting means includes a screw 110 with a coated base and a nut 112 (Figures 2 and 3) which contacts the arm 108 against one side. The expanded portion 115 of the piston 114 also contacts the arm 108 and the spring 116 presses against the extension 115 to force the piston 114 against the arm 108. By turning the screw 110, the position of the openings 86 relative to the fixed openings 72 is adjusted.

Since the fan outlet pressure is available in the filling chamber 66 to produce the jets 102, variations in the material in the combustion chamber 106 do not have a significant effect on these jets. Sudden changes in traction that occur on 6,58,014 windy days in the chimney or gas duct and cause pressure fluctuations in the combustion chamber 106 therefore do not adversely affect the operation of the burner.

Two ignition electrode sticks 118 extend through insulating ceramic sleeves 120 secured to the recesses of the portion 96 by a mounting rod 124 secured by a screw. The rear ends of these pins 118 form resilient contacts 128 which become connected by respective high voltage terminals 130 (Figure 1) when the cover 54 is closed. The flexibility of the contact 128 allows the portion 96 to be adjusted in place without breaking the contact.

The electrode sticks 118 extend through the openings 86 in the rotatable septum 82 and the arcuate slot 76 in the fixed septum 68. The electrode sticks 118 are bent at their front ends to form converging electrode tips 132 (Figure 3). (In Figure 4, the electrodes 118 are omitted to illuminate the operation more clearly. The location of the ignition spark is indicated by a plus sign inside a small circle).

As shown in Figure 4, a smaller portion 99 of the compressed air flow flows into and out of the nozzle support tube 84 to cool the fuel line 44 and the nozzle 46. This cooling air 99 is discharged through a plurality of small holes 133 in the cam ring 88 (Figure 4). This cam ring 88 is preferably chamfered back radially out of the nozzle tip so as to cause the direction of the air jets 135 to change to the downstream side. Said jets 135 are formed by undiluted air which assists in providing ignition and retaining a stable blue flame behind the mouth 136 of the fuel injection area 105. By changing the direction of the jets 135 in the combustion chamber 106 obtained according to Fig. 4, a more dispersed and uniform blue flame, which provides better heat transfer and more stable combustion over a wider calorific value range.

A metallic, concentric mixing sleeve 134 surrounds the front of the tube 84, forming an annular dilution zone 104 (for chemical modification) for air and also a portion of the recycle path. The agitator sleeve 134 extends downstream of the nozzle 46 to form a fuel injection area 105 on the downstream side to which the fuel jet is directed. Preferably, the fuel jet 48 does not hit the lip sleeve 134 at the mouth 136. In this preferred embodiment, the diameter of the fuel injection area 105 is greater than its length L, measured axially from the nozzle 46 to the mouth 136 of the sleeve.

Attached to the mouth 136 of the sleeve 134 is a radial flange 138 or the like, which is covered by a refractory separating layer 137, the shoulder 141 of which is held. This part 138 acts as a reversing means which causes the combustion products to circulate again over the uninsulated heat exchange surfaces of the fluid heater 14. The reversing means 138 and the sleeve means 134 function to form low pressure recirculation pathways 139 and 140 for gaseous combustion products to be recycled to the ring zone 104. These recirculating combustion products are indicated by arrows 142-1,142-2 and 142-3.

It should be noted that the recycle path 139 and 140 include an annular portion 139 extending radially inwardly along the exposed metal wall 144 of the heater 14 jacket 146. The recycle path also includes a cylindrical portion.

As shown in Figure 1, the thermal insulation 150 may surround the combustion chamber 106. The rear of the combustion chamber 106 may be covered by a removable panel 152 forming a passage 154 for hot combustion gases flowing through tubular heat exchange portions 156 to the gas passage box 158 and flue 160.

The sleeve 134, part 138 and insulation and spacers 162 can be fabricated in series for installation in field fluid heaters 14.

The multiple jets 102 entering the rear of the air dilution zone 104 provide a low pressure in use in the region 164 near the orifices 72, as shown in Figure 2. This low pressure region 164 causes the gaseous combustion products to recirculate as indicated by arrows 142-1,142-2 and 142-3. These circulating gases 142 pass through efficient heat exchange with the bare metal walls 151 and 144. The heat exchange achieved is so efficient that the temperature of the recycled gases 142-3 at the back of the sleeve 134 is preferably below 426 ° C.

The jets 102 provide efficient momentum exchange with the recirculating gases 142-3, causing a large amount of the recirculating fuel gases to move forward through the zone 104 and thus provide thorough mixing between the combustion air (in the jets 102) and the recirculating gases 142-3. When mixed with the cooled, recycled gases 142-3, the combustion air thus becomes diluted and its composition becomes chemically modified.

This dilution of the majority of the combustion air and its chemical transformation takes place in the ring zone 104 before the diluted air enters the fuel injection zone 105 downstream. The diluted air and the fuel jet 48 effectively mix in the zone 105. Since most, namely about 80-90%: a the combustion air has become diluted before it reaches the fuel, the burner 10 does not have much chance of burning with a yellow flame due to gusty wind at the gas duct outlet or despite adjustment over a wide calorific value range.

The undiluted air jets 135 provide a vortex flow 166 near the cam ring 88 to draw the mist formed by the small fuel droplets from the jet 48 into the ignition spark, which provides rapid ignition of the fuel. The front of the flame moves rapidly to the downstream side and the flame stabilizes in the combustion chamber 106.

The cross-sectional area of the flow paths suddenly increases downward from the mouth 136 so that a backward rotating vortex 168 of the blue flame occurs. This backward rotating vortex 168 extends around the mouth 136, retaining and stabilizing the blue flame and in the combustion chamber 106. The dispersed, undiluted air jets are 136, but pass into the vortex 168 to obtain a slightly larger amount of oxygen in the stabilizing vortex 168, which has the advantage of retaining the blue flame and spreading it throughout the combustion chamber 106. The air jets 135 preferably disperse at an internal angle of 30-60 ° and also cause the fuel jet to spread preferably from the burner mouth substantially the entire cross-sectional area of the shepherded air flow.

Figure 6 shows a different fluid heater 146 of the burner 10, which is a water heater with a supply line 190 and a hot water supply line 192. The shape of the hot water tank 146 is conventional and includes a bare, concave metal surface 151. The combustion chamber 106 is formed by a special material 150 supported by a metal cylinder 196, and the glass fiber insulating material 198 surrounds the chamber 106. The flange 200 extends around the upper end of the chamber 106. The hot, gaseous combustion products enter the upper space 194 in heat exchange with the surface 151 and are directed downward. The flange 200 redirects the gases up into the annular passage 202 and out through the gas line 160. An outer, insulated shell 204 surrounds the channel 202.

Around the rear end of the agitator sleeve 134 is an annular hollow portion 206 which forms an annular recirculation chamber 140. The hollow portion 206 includes a conduit portion 208 forming a passage 139 communicating with the chamber 140 and the space 194.

The cross-sectional area of the combustion chamber 106 increases locally behind the lip 136 at the mouth of the fuel injection area 105, providing a backward rotating annular vortex 168. As mentioned above, such a rear vortex 168 assists in retaining a stable blue flame in the combustion chamber 106.

The plurality of air jets from the burner 10 draw some of the gas products down through the passages 139 and 140 and enter the air dilution zone 104, where the air changes chemically.

Figure 7 shows a burner fluid with a closed heater 14B having a supply line 190 connected to a coil 222 of a heat exchanger 12. The coil 222 is connected to a hot water supply line 192. This heater 14B includes a first, elongate, cylindrical portion 224 made of rigid insulator 150. which forms the combustion chamber 106. The cross-sectional area of the sleeve means 134 downwards increases abruptly, forming a backward vortex 168 in the combustion chamber 106.

The first cylindrical portion 224 is supported by intermediate portions 228 made of the insulating material, concentrically within the second, larger, elongate, and cylindrical portion made of the insulating material 150. The portions 224 and 232 are spaced apart to form a substantially annular, cylindrical passage 234 that communicates with the end of the chamber 106 away from the fuel injection area 105. The portion 234 has a metal sheath 236 secured by brackets 238 to a cylindrical metal shell 240.

The second portion 232 and the housing 240 form a space 241 for the coil 222, which space communicates with the outlet chamber 242 and the conduit 160. The shell has an end cap 244.

A useful heat exchange occurs between the gases passing through recirculation paths 139 and 140 and the fluid-cooled heat radiator coil 222 so that these recirculated gases are cooled, preferably to less than 426 ° C, before entering zone 104, where the air is diluted and further diluted.

It is preferred that a significant pressure difference occur between the connection between the passages 234 and 139 and the low pressure region 164 in the vicinity of the strong jets of air entering zone 104; therefore, very efficient recycling of cooled combustion products along roads 139 and 140 is achieved.

Figure 8 shows graphically the effects of excess air on nitrogen oxide (NO) discharges 252 and carbon monoxide (CO) discharges 253 in a conventional fuel oil 10 5801 4 burner with a flame retaining end heating a commercial outdoor water heater, and also at 256 and 257 in a burner that is an embodiment of the present invention and which heats the same water heater. This water heater was modified by removing the insulation near the opening 22 at 144 and 151, as shown in Figure 4. Both burners were tested in this water heater after the insulation was removed. (This modification reduced NO discharges for a conventional burner compared to a burner with insulation at 144 and 151, and thus this modification did not adversely affect the performance of a conventional burner). Both burners were operated at 2.85 L to 3.04 L (am. 0.75 to 0.80 Gall.) Or 3.4 L to 3.63 L (Am. Gall.) No. 2 fuel oil per hour using fuel standard high pressure spray nozzles.

Figure 9 shows graphically the smoke discharges and the efficiency values of the furnace in relation to the excess air under stable operating conditions. Smoke eruptions 250 and 254 are marked relative to the vertical axis on the left with Bachrach numbers. The oven efficiency values are marked at 251 and 255 in relation to the vertical axis on the right.

Excess air is an independent variable that exceeds the stoichiometric ratio of air to fuel by a percentage. For example, 10% excess air means that the amount of air supplied through the burner exceeds the stoichiometric ratio by ten percent, etc.

The following are claims within the scope of which the various details of the invention may vary within the scope of the inventive idea.

Claims (17)

A method of burning liquid hydrocarbons in a burner comprising a rear open sleeve (134), the outlet of which leads to a combustion chamber into which liquid fuel is injected from a nozzle (46) into an injection zone in the sleeve (134), thereby introducing a plurality of combustion air jets (102) and the gaseous combustion products are recirculated by suction from the combustion chamber to the inlet of the sleeve (134) and then into the sleeve (134), characterized in that the fuel injection zone (105) is arranged close to the mouth of said sleeve (134). 136) that said nozzle (46) is cooled by a smaller portion (99) of combustion air, after which this smaller portion (99) of combustion air is allowed to flow directly into the fuel injection zone so that a larger portion (101) of combustion air is supplied as said plurality of jets (102) that the recycled gaseous combustion products (142-1 to 142-3) are led to a heat liquid-cooled heat exchanger. to cool recyclable gaseous products (102) and to mix said combustion air jets (102) with recyclable gaseous products in a mixing zone (104) located upstream of the fuel injection zone (105) so that the combustion air is thus mixed and chemically altered. before it reaches said fuel injection zone (105), which results in a stable, blue flame with a low content of nitrogen oxides and particles in the combustion chamber. A method according to claim 1, characterized in that said smaller part (99) of combustion air is fed to the fuel injection zone (105) in a plurality of air jets (135) directed outwards around the fuel droplet cloud (48) to amplify the radial scattering of the fuel cloud. A method according to claim 2, characterized in that a rearwardly rotating, substantially annular vortex (168) is provided in the combustion chamber near the fuel injection zone (105) and in that the air jets (135) are directed substantially against the vortex (168) to provide a certain oxygen content. rising in the context of a backward vortex to provide stable stability of the blue flame. A method according to claim 3, characterized in that the gaseous combustion products are recycled in a recirculation path the starting point of which is close to said backward rotating vortex (168). 5,801 4 A method according to claim 2,3 or 4, wherein the liquid fuel is injected in the form of small droplets (48) spreading downstream towards the combustion chamber, characterized in that the air streams (135) are distributed around the fuel distribution pattern and are directed outwards so as to that they propagate downstream, and that the fuel cloud is ignited at the point between the propagating fuel cloud and the dispersing air jets, causing the airflow pattern to draw streaks of small fuel droplets from the injection pattern to the proximity of the ignition fuel. A method according to claim 1,2,3,4 or 5, characterized in that the air mixing zone (104) is annular and that said smaller part (99) of combustion air is supplied substantially axially through the region of the mixing zone (104). A method according to claim 1,2,3,4,5 or 6, characterized in that said smaller part (99) and said larger part (101) of combustion air constitute substantially the entire air flow entering the combustion chamber, whereby substantially all of the combustion air volume becomes into the fuel injection zone (105). Method according to Claim 1, 2, 3, 4, 5, 6 or 7, characterized in that the fuel injection zone (105) is cylindrical with a diameter greater than its length. A method according to claim 1,2,3,4,5,6,7 or 8, characterized in that the flow of the larger part (101) of the combustion air is restricted in a plurality of spaced openings (72) to control the combustion process. An apparatus for burning liquid hydrocarbons for use in the method of claims 1-9, the apparatus comprising a sleeve (134) having an open at the rear and an outlet leading to a combustion chamber (106) in a liquid-cooled heat exchanger, a nozzle (46) comprising liquid fuel. to supply a cloud to said sleeve (134), a plurality of openings (72) arranged in the inlet region of the sleeve (134) through which a plurality of air jets (102) are led into the inlet and through the sleeve (134) and a duct (139,140) through which gaseous combustion products from the combustion chamber (106) to the inlet and through the sleeve (134), characterized in that said nozzle (46) is arranged at the front of the sleeve (134) to form a fuel injection zone (105) at the sleeve outlet (136) so that the air tube ( 84) extends through the inlet of the sleeve (134) and into the sleeve (134) to supply a smaller portion (99) of combustion air to the nozzle (46) proximity to cool the nozzle that the sleeve (134) is wider than the air tube (84) and defines an annular mixing zone (104) within the sleeve (134) around the air tube (84), the openings (72) being directed toward the annular mixing zone (104) so that said plurality of air jets (102) passing through the annular mixing zone (104) and remixing with the recycled gaseous combustion products as they flow through the annular mixing zone (104) toward the fuel injection zone (105) and that the liquid-cooled heat exchanger is re-cooled (12; 146; 148); recycled gaseous combustion products, which results in the formation of a stable blue flame with a low content of nitrogen oxides and particles in the combustion chamber (106). ✓ Device according to Claim 10, characterized in that a deflection plate (137, 138) is arranged separately from one part (151) of the liquid-cooled heat exchanger (12) so as to limit the recirculation path (142-1,142-2) which leads to to the recycling channel (140). 11 5 801 4 Device according to claim 10 or 11, characterized in that the liquid-cooled heat exchanger (14B) comprises a first elongate, cylindrical part (224) delimiting the combustion chamber (106) so that the cross-sectional area of said part (224) is larger than the sleeve ( 134) the area of the outlet (136) (Fig. 7). Device according to claim 12, characterized in that a second, larger, elongate part (232) made of heat-insulating material is arranged around said first part (224), so that the first and second parts (224,232) are thus radially and axially separated. that they delimit a substantially annular, cylindrical channel (234) in communication with the opposite end of the combustion chamber (106) relative to the outlet (136) of the sleeve (134) so as to be arranged around the second part (232), preferably of heat-resistant metal. , a sheath (240), the sheath (240) and the second portion (232) being radially and axially spaced apart so as to substantially define the annular space (241) communicating with the annular channel (234), and the annular space a fluid space (222) is provided for the flow of fluid during heating through this space (222) so that the annular material The channel (234) is reconnected to the recycle channel (140) (Fig. 7). Device according to claim 10, 11, 12 or 13, characterized in that the air pipe (84) has a front part surrounding the fuel nozzle (46) and is provided with openings (133) for allowing the combustion air cooled by the nozzle (46) to enter the fuel injection zone (105). . 14 S 8014 Device according to Claim 10, 11, 12, 13 or 14, characterized in that the sleeve (134) has a relatively large diameter and a short overall length, the ratio of length to diameter not exceeding 2: 1. Device according to one of Claims 10, 11, 12, 13, 14 or 15, characterized in that air openings (82) are connected to the openings (72) for adjustable throttling of the air flow through the openings (72) and in that the device has control means. (110,114) to adjust the air supply. Device according to any one of claims 10, 11, 12, 13, 14, 15 or 16, characterized in that the openings (133) are arranged to conduct a smaller part (99) of said combustion air in a plurality of outwardly directed air jets around the fuel jet cloud, e.g. 60 °. 5,801 4